Equation for the service life of a diesel engine by cylinder pressure . ...... consisting of six cylinders Ashok Leyland diesel engine, heat recovery heat exchanger ...... The sump level is to be according to manufacturer's /shipbuilder's instructions.
Alexandria University Faculty of Engineering
STUDY OF OPTIMUM DESIGN FEATURES OF MARINE DIESEL ENGINE
A Graduation Project Report submitted to the Department of Naval Architecture and Marine Engineering Faculty of Engineering – Alexandria University for the partial fulfilment of the requirements of the B.Sc. degree
by Bassem Saeed Zaki Hanna Emil Abd Elmessih Eshak Botros Michael Nabil Thabit Mourqs Peter Refaat Gaber kaldas Supervised by Prof. Dr. Mohamed M Elgohary Dr. Ibrahim S Seediek Jul 2018
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Acknowledgement
First, we would like to thank God. Who have given us the power to trust in our self and achieve our dreams. Thanks for everyone who helped me in completing this work in the Marine Engineering and Naval Architecture department at the Faculty of Engineering, Alexandria University and Arab Academy for Science, Technology & Maritime Transport. we submit our highest appreciation to our advisors Prof. Dr. Mohamed M Elgohary and Dr. Ibrahim S Seediek who share for of this work to be under his valuable supervision. Finally, we would like to thank every professor who specialized some of his time and let our extract some advices from him, and those who supported and encouraged us through carrying out this work. Thanks to all those people out there who gave us help by any means they could offer.
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Declaration
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Table of Contents
ACKNOWLEDGEMENT .............................................................................................. II DECLARATION ......................................................................................................... III TABLE OF CONTENTS .............................................................................................. IV TABLE OF FIGURE ....................................................................................................IX TABLE OF EQUATIONS .............................................................................................XI TABLE OF TABLE ....................................................................................................XIII ABSTRACT ............................................................................................................ XIV CHAPTER (1)........................................................................................................... 19 WASTE HEAT RECOVERY (WHRS) FOR REDUCTION OF FUEL CONSUMPTION & EMISSIONS ..................................................................................................................... 19 1
INTRODUCTION ............................................................................................... 19
2
WASTE HEAT RECOVERY SYSTEMS .................................................................... 22 2.1
POWER TURBINE AND GENERATOR (PTG) .......................................................................................... 24
2.2
STEAM TURBINE, POWER TURBINE, AND GENERATOR (ST-PT) ................................................................ 26
2.3
EXHAUST GAS BOILER AND STEAM SYSTEMS......................................................................................... 27
2.3.1
Single-pressure steam system .............................................................................................. 28
2.3.2
Dual-pressure steam system ................................................................................................ 29
2.4
ORGANIC RANKINE CYCLE (ORC) ..................................................................................................... 31
2.4.1
Experimental Setup and IC engine model ............................................................................ 31
2.4.2
Configuration with all waste heat sources. A single cycle. .................................................. 31
2.4.3
Configuration with all heat sources. Binary Cycle ................................................................ 33
2.5
WASTE HEAT RECOVERY FROM DIESEL ENGINE EXHAUST USING PHASE CHANGE MATERIAL ............................. 35
2.5.1
Experimental Setup and procedures .................................................................................... 35
2.5.2
Results and discussion ......................................................................................................... 38
2.5.2.1 2.5.3
3
Performance of heat recovery heat exchanger ............................................................... 38 Summary of phase change systems ..................................................................................... 42
CALCULATION OF DOUBLE ACTING DIESEL ENGINE ........................................... 43 3.1
DIESEL FUEL.................................................................................................................................. 43
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3.2
4
STEAM ........................................................................................................................................ 43
EMISSION EFFECTS OF USING WHRS ................................................................. 43 4.1
LIMITATIONS OF PARAMETERS AND INPUT VALUES ASSUMED FOR STEAM TURBINE CYCLE CALCULATIONS ......... 44
CHAPTER (2)........................................................................................................... 45 SPECIFIC FUEL CONSUMPTION................................................................................ 45 5
INTRODUCTION ............................................................................................... 45
6
CRUDE OIL ....................................................................................................... 45 6.1
CRUDE OIL FIELD FORMED ............................................................................................................... 45
6.2
COMPOSITION AND CLASSIFICATION OF CRUDE OIL ............................................................................... 46
6.3
CRUDE OIL REFINING AND STOCKS FOR MARINE FUEL BLENDING .............................................................. 47
6.3.1
7
Typical refining schemes and the influence on marine fuels ............................................... 48
FUEL OIL .......................................................................................................... 49 7.1
FUEL OIL APPLICATIONS ................................................................................................................... 49
7.2
FUEL SPECIFICATIONS ..................................................................................................................... 49
8
MARINE DIESEL FUEL/MARINE GAS OIL ............................................................ 52 8.1
DIESEL FUEL GRADES ..................................................................................................................... 52
8.2
HIGH SPEED DIESEL (HSD).............................................................................................................. 53
8.2.1
9
Application: .......................................................................................................................... 53
BIODIESEL ........................................................................................................ 55
10
NATURAL GAS .............................................................................................. 55
11
NUCLEAR...................................................................................................... 56
CHAPTER (3)........................................................................................................... 57 SERVICE LIFE PREDICTION OF DIESEL ENGINE .......................................................... 57 12
INTRODUCTION ............................................................................................ 57
13
MATERIALS AND METHODS .......................................................................... 58
14
DIESEL ENGINE LIFE PREDICTION MODEL ...................................................... 59
14.1.
RELATIONSHIP BETWEEN CYLINDER AIR LEAKAGE AND DIESEL ENGINE LIFE:................................................. 59
14.1.1.
Basic rated wear life:....................................................................................................... 59
14.1.2.
Basic rating of the air leakage of the cylinder: ............................................................... 59
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14.2.
RELATIONSHIP BETWEEN THE AIR LEAKAGE OF THE CYLINDER AND THE SERVICE LIFE OF DIESEL ENGINE: ........... 60
14.3.
RELATIONSHIP BETWEEN CYLINDER PRESSURE AND THE LIFE OF DIESEL ENGINE: .......................................... 61
14.4.
RELATIONSHIP BETWEEN THE CYLINDER PRESSURE P AND THE CYLINDER AIR LEAKAGE Q IN EQUAL VOLUME AND
ISOTHERMAL CONDITION: ACCORDING ....................................................................................................................... 61
14.4.1.
Equation for the service life of a diesel engine by cylinder pressure ............................... 63
14.4.2.
Rated air leakage and rated pressure ............................................................................. 63
14.5. DIESEL ENGINE
FUNCTIONAL RELATIONSHIP BETWEEN FUEL INJECTION PRESSURE, ENGINE OIL PRESSURE AND SERVICE LIFE OF ................................................................................................................................................ 64
15
RESULTS ....................................................................................................... 68
16
DISCUSSION ................................................................................................. 70
17
EXAMPLE ..................................................................................................... 71
17.1
SULZER RTA AND RT-FLEX ENGINES.................................................................................................. 71
CHAPTER (4)........................................................................................................... 73 ENVIRONMENTAL POLLUTION BY DIESEL ENGINE ................................................... 73 18
INTERDICTION .............................................................................................. 73
19
THE EMISSIONS FROM DIESEL ENGINES ........................................................ 73
19.1
CARBON MONOXIDE (CO) ............................................................................................................... 75
19.2
HYDROCARBONS (HC) .................................................................................................................... 75
19.3
PARTICULATE MATTER (PM) ............................................................................................................ 76
19.4
NITROGEN OXIDES (NOX) ............................................................................................................... 77
20
EMISSION CONTROL SYSTEMS FOR DIESEL ENGINE VEHICLES ........................ 79
20.1
DIESEL OXIDATION CATALYST (DOC) ................................................................................................. 81
20.2
DIESEL PARTICULATE FILTER (DPF) .................................................................................................... 84
20.3
SELECTIVE CATALYTIC REDUCTION (SCR) ............................................................................................ 85
21
EMISSION CALCULATION FOR MODELING ..................................................... 89
CHAPTER (5)........................................................................................................... 90 ENGINE MODELING SYSTEMS ................................................................................. 90 22
INTERDUCTION ............................................................................................ 90
23
FUEL SYSTEM ............................................................................................... 90
23.1
FUEL INJECTION SYSTEM COMPONENTS ............................................................................................. 91
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The fuel tanks .................................................................................................................. 91
23.1.2
The fuel supply pump ...................................................................................................... 91
23.1.3
Fuel Filter ........................................................................................................................ 92
23.1.4
Fuel Coolers ..................................................................................................................... 92
23.1.5
Fuel Heaters .................................................................................................................... 92
23.1.6
Fuel injector..................................................................................................................... 93
24
LUBRICATION SYSTEM .................................................................................. 94
24.1
MAIN ENGINE LUBRICATING OIL SYSTEM: ............................................................................................ 94
24.2
LUBRICATING OIL SYSTEM: ............................................................................................................... 94
24.2.1
Cylinder lubrication ......................................................................................................... 95
24.2.2
Lubricating Oil Sump Level .............................................................................................. 96
24.2.3
Pre-Lubrication Pumps .................................................................................................... 97
25
AIR COOLING SYSTEM .................................................................................. 97
25.1
26
AIR COOLERS ................................................................................................................................ 98
FRESH WATER COOLING SYSTEM .................................................................. 99
26.1
FRESH WATER COOLING FOR ONE CYLINDER ...................................................................................... 100
CHAPTER (6)......................................................................................................... 101 INTERNAL COMPANTION ENGINE PARTS .............................................................. 101 27
INTRODUCTION .......................................................................................... 101
28
PRINCIPAL PARTS OF AN ENGINE ................................................................ 102
28.1
CYLINDER AND CYLINDER LINER ...................................................................................................... 103
28.1.1
Design of a Cylinder ...................................................................................................... 103
28.1.1.1
Thickness of the cylinder wall. ...................................................................................... 103
28.1.1.2
Bore and length of the cylinder ..................................................................................... 105
28.2
CYLINDER HEAD. .......................................................................................................................... 107
28.3
PISTON ...................................................................................................................................... 108
28.3.1
Design Considerations for a Piston ............................................................................... 109
28.3.2
Material for Pistons....................................................................................................... 109
28.3.3
Piston Head or Crown ................................................................................................... 110
28.3.4
Piston Rings ................................................................................................................... 112
28.3.5
Piston Barrel .................................................................................................................. 114
28.3.6
Piston Skirt .................................................................................................................... 114
28.3.7
Piston Pin ...................................................................................................................... 115
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28.4
CONNECTING ROD ....................................................................................................................... 118
28.4.1
Dimensions of cross-section of the connecting rod ....................................................... 120
28.4.2
Dimensions of the crankpin at the big end and the piston pin at the small end ........... 123
28.5
CRANKSHAFT .............................................................................................................................. 125
28.5.1
Material and manufacture of Crankshafts .................................................................... 125
28.5.2
Bearing Pressures and Stresses in Crankshaft ............................................................... 126
28.5.3
Design of Crankshaft ..................................................................................................... 127
29
GAS PRESSURE AND HEAT BALANCE ........................................................... 128
30
SPECIFICATIONS OF THE MODEL ENGINE .................................................... 130
31
MODEL DESIGN CALCULATIONS .................................................................. 131
31.1
HEAT BALANCE ENERGY................................................................................................................. 131
31.2
PISTON HEAD ............................................................................................................................. 132
31.3
PISTON PIN ................................................................................................................................ 132
31.4
CONNECTING ROD ....................................................................................................................... 133
31.5
CRANK SHAFT ............................................................................................................................. 134
31.6
CYLINDER ................................................................................................................................... 134
31.7
CYLINDER HEAD ........................................................................................................................... 134
32
2D DRAWINGS OF MODEL ENGINE.............................................................. 135
33
DESIGN CALCULATION USING MATLAB CODES ............................................ 136
34
GEOMETRY MODELING USING SOLIDWORKS .............................................. 138
34.1
PISTON HEAD AND PIN ................................................................................................................ 138
34.2
CONNECT ROD & CONNECT ROD BOTTOM ........................................................................................ 140
34.3
CRANK SHAFT ............................................................................................................................. 141
34.4
ASSEMBLY PARTS OF MODELING ..................................................................................................... 142
CONCLUSIONS...................................................................................................... 144 REFERENCES......................................................................................................... 145
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Table of figure Figure 0-1 General Considerations in Machine Design .................................................................................. xviii Figure 2-1 Waste Heat Recovery system principles ........................................................................................ 23 Figure 2-2 Schematic diagram of the WHRS-PTG system ................................................................................ 24 Figure 2-3 WHRS system turbine generator unit ............................................................................................ 25 Figure 2-4 Full WRHS system and power turbine unit..................................................................................... 26 Figure 2-5 Schematically diagram of the WHRS ST-PT system ........................................................................ 27 Figure 2-6 Process diagram pressure exhaust gas boiler system ..................................................................... 28 Figure 2-7 Temp. transmission diagram for dingle pressure steam sys. .......................................................... 28 Figure 2-8 Temp. transmission diagram for the dual pressure steam system ................................................. 29 Figure 2-9 Process diagram for the dual pressure exhaust gas boiler system ................................................. 30 Figure 2-10 WHRS recovery ratios .................................................................................................................. 30 Figure 2-11 Schematic diagram of the experimental setup ............................................................................. 36 Figure 2-12 Temp. variation of the exhaust gas and the water at the inlet and outlet of the HRHE at 25% load. .............................................................................................................................................................. 39 Figure 2-13 Temp. variation of the exhaust gas and the water at the inlet and outlet of the HRHE at 50% load. .............................................................................................................................................................. 39 Figure 2-14 Temp. variation of the exhaust gas and the water at the inlet and outlet of the HRHE at 75% load. .............................................................................................................................................................. 40 Figure 2-15 Temp. variations of the exhaust gas and the water at the inlet and outlet of the HRHE at full load. .............................................................................................................................................................. 40 Figure 2-16 shows the variation of the heat extraction rate from the exhaust gas through the HRHE ............ 41 Figure 2-17 Heat Energy saved in the storage tank for different loading conditions ....................................... 41 Figure 6-1 Crude oil distillation ...................................................................................................................... 47 Figure 7-1 Marine Fuel Sulphur Limits ............................................................................................................ 50 Figure 14-1 Life curve of diesel engine ........................................................................................................... 60 Figure 14-2 Relationship between fuel injection pressure and the life of diesel engine.................................. 65 Figure 14-3 Relationship between oil pressure and the life of diesel engine .................................................. 67 Figure 14-4 Types of modified state parameters for the life prediction of diesel engine ................................ 67 Figure 17-1 Inspection or Overhaul Intervals and Lifetimes ............................................................................ 71 Figure 19-1 The compositions of diesel exhaust gas ....................................................................................... 74 Figure 20-1 Diesel oxidation catalyst .............................................................................................................. 81 Figure 20-2 Filtration of DPF ........................................................................................................................... 83 Figure 20-3 Typical SCR system with DOC ....................................................................................................... 87 Figure 22-1 main functions of diesel fuel injection system ............................................................................. 90 Figure 23-2 Fuel injectors parts name ............................................................................................................ 93
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Figure 24-1 Lubrication Oil system ................................................................................................................. 95 Figure 24-2 Lubrication oil system for one-cylinder engine diagram ............................................................... 96 Figure 25-1 Cross flow scavenge cycle ............................................................................................................ 97 Figure 25-2 Cross flow scavenge diagram for one-cylinder engine.................................................................. 98 Figure 26-1 cooling system diagram ............................................................................................................... 99 Figure 26-2 Fresh water cooling diagram for one-cylinder engine ................................................................ 100 Figure 28-1 Internal combustion engine parts. ............................................................................................. 102 Figure 28-2 Dry and wet liner. ...................................................................................................................... 103 Figure 28-3 Piston for I.C. engines (Trunk type). ........................................................................................... 108 Figure 28-4 Piston rings. ............................................................................................................................... 112 Figure 28-5 Full floating type piston pin. ...................................................................................................... 115 Figure 28-6 Semi-floating type piston pin. .................................................................................................... 116 Figure 28-7 Piston Pin diminution ................................................................................................................ 117 Figure 28-8 Connecting rod. ......................................................................................................................... 118 Figure 28-9 Buckling of connecting rod. ....................................................................................................... 121 Figure 28-10 I-section of connecting rod. ..................................................................................................... 121 Figure 28-11 Types of crankshafts. ............................................................................................................... 125 Figure 28-12 section of Crankshaft ............................................................................................................... 127 Figure 29-1 Heat Balance Diagram of a nominally rated to model ............................................................... 129 Figure 34-1 3D view of piston ....................................................................................................................... 138 Figure 34-2 section of 3D modeling of piston ............................................................................................... 138 Figure 34-3 3D plane view of piston ............................................................................................................. 139 Figure 34-4 3D Piston pin ............................................................................................................................. 139 Figure 34-5 3D connecting rod view ............................................................................................................. 140 Figure 34-6 3D Section of connecting rod ..................................................................................................... 140 Figure 34-7 3D Crank shaft view ................................................................................................................... 141 Figure 34-8 3D assembly model engine ........................................................................................................ 142 Figure 34-9 3D section of assembly model engine ........................................................................................ 143
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Table of equations Equation 21-1 ................................................................................................................................................. 89 Equation 28-1 ............................................................................................................................................... 104 Equation 28-2 ............................................................................................................................................... 104 Equation 28-3 ............................................................................................................................................... 104 Equation 28-4 ............................................................................................................................................... 105 Equation 28-5 ............................................................................................................................................... 106 Equation 28-6 ............................................................................................................................................... 106 Equation 28-7 ............................................................................................................................................... 106 Equation 28-8 ............................................................................................................................................... 107 Equation 28-9 ............................................................................................................................................... 110 Equation 28-10 ............................................................................................................................................. 111 Equation 28-11 ............................................................................................................................................. 111 Equation 28-12 ............................................................................................................................................. 113 Equation 28-13 ............................................................................................................................................. 113 Equation 28-14 ............................................................................................................................................. 114 Equation 28-15 ............................................................................................................................................. 114 Equation 28-16 ............................................................................................................................................. 114 Equation 28-17 ............................................................................................................................................. 114 Equation 28-18 ............................................................................................................................................. 115 Equation 28-19 ............................................................................................................................................. 117 Equation 28-20 ............................................................................................................................................. 117 Equation 28-21 ............................................................................................................................................. 117 Equation 28-22 ............................................................................................................................................. 117 Equation 28-23 ............................................................................................................................................. 120 Equation 28-24 ............................................................................................................................................. 120 Equation 28-25 ............................................................................................................................................. 121 Equation 28-26 ............................................................................................................................................. 121 Equation 28-27 ............................................................................................................................................. 121 Equation 28-28 ............................................................................................................................................. 122 Equation 28-29 ............................................................................................................................................. 122 Equation 28-30 ............................................................................................................................................. 122 Equation 28-31 ............................................................................................................................................. 122 Equation 28-32 ............................................................................................................................................. 122 Equation 28-33 ............................................................................................................................................. 122 Equation 28-34 ............................................................................................................................................. 124
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Equation 28-35 ............................................................................................................................................. 124 Equation 28-36 ............................................................................................................................................. 124 Equation 28-37 ............................................................................................................................................. 124 Equation 28-38 ............................................................................................................................................. 124 Equation 28-39 ............................................................................................................................................. 127 Equation 28-40 ............................................................................................................................................. 127 Equation 28-41 ............................................................................................................................................. 127 Equation 28-42 ............................................................................................................................................. 127 Equation 28-43 ............................................................................................................................................. 127 Equation 29-1 ............................................................................................................................................... 128 Equation 29-2 ............................................................................................................................................... 128 Equation 29-3 ............................................................................................................................................... 128 Equation 29-4 ............................................................................................................................................... 128 Equation 29-5 ............................................................................................................................................... 128 Equation 29-6 ............................................................................................................................................... 128 Equation 29-7 ............................................................................................................................................... 128 Equation 29-8 ............................................................................................................................................... 129 Equation 29-9 ............................................................................................................................................... 129 Equation 29-10 ............................................................................................................................................. 129 Equation 29-11 ............................................................................................................................................. 129 Equation 29-12 ............................................................................................................................................. 129 Equation 29-13 ............................................................................................................................................. 129 Equation 29-14 ............................................................................................................................................. 129
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Table of table
Table 1-1 Summarizes results ......................................................................................................................... 21 Table 2-1 Property of paraffin phase change material .................................................................................... 38 Table 3-1 Double acting calculations for diesel fuel ........................................................................................ 43 Table 3-2 Double acting calculations for steam engine ................................................................................... 43 Table 7-1 Requirements for marine distillate fuels ......................................................................................... 51 Table 8-1 Diesel Fuel Grades .......................................................................................................................... 52 Table 8-2 PHYSICAL AND CHEMICAL PROPERTIES ........................................................................................... 54 Table 8-3 IDENTITY OF MATERIAL .................................................................................................................. 54 Table 8-4 FIRE AND EXPLOSION HAZARD’S DATA ........................................................................................... 54 Table 8-5 REACTIVE HAZARDS ........................................................................................................................ 54 Table 8-6 HAZARD SPECIFICATION ................................................................................................................. 55 Table 15-1 Experimental results of the diesel engine bench test .................................................................... 69 Table 19-1 Euro standards of E.U for heavy-duty vehicles at 2012 ................................................................. 79 Table 21-1 Emission calculation...................................................................................................................... 89 Table 28-1 Allowance for reboring for I. C. engine cylinders. ........................................................................ 105 Table 28-2 Allowable bending and shear stresses. ....................................................................................... 126 Table 30-1 Specifications of model ............................................................................................................... 130 Table 31-1 Heat balance calculations ........................................................................................................... 131 Table 31-2 Piston head calculations ............................................................................................................. 132 Table 31-3 Piston pin calculations ................................................................................................................ 132 Table 31-4 Connecting rod calculations ........................................................................................................ 133 Table 31-5 Crank shaft calculations .............................................................................................................. 134 Table 31-6 cylinder calculations ................................................................................................................... 134 Table 31-7 cylinder head calculations ........................................................................................................... 134
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Abstract The subject Machine Design is the creation of new and better machines and improving the existing ones. A new or better machine is one which is more economical in the overall cost of production and operation. The process of design is a long and time consuming one. From the study of existing ideas, a new idea must be conceived. The idea is then studied keeping in mind its commercial success and given shape and form in the form of drawings. In the preparation of these drawings, care must be taken of the availability of resources in money, in men and in materials required for the successful completion of the new idea into an actual reality. In designing a machine component, it is necessary to have a good knowledge of many subjects such as Mathematics, Engineering Mechanics, Strength of Materials, Theory of Machines, Workshop Processes and Engineering Drawing.
a) Classifications of Machine Design The machine design may be classified as follows: 1. Adaptive design. In most cases, the designer’s work is concerned with adaptation of existing designs. This type of design needs no special knowledge or skill and can be attempted by designers of ordinary technical training. The designer only makes minor alternation or modification in the existing designs of the product. 2. Development design. This type of design needs considerable scientific training and design ability in order to modify the existing designs into a new idea by adopting a new material or different method of manufacture. In this case, though the designer starts from the existing design, but the final product may differ quite markedly from the original product. 3. New design. This type of design needs lot of research, technical ability and creative thinking. Only those designers who have personal qualities of a sufficiently high order can take up the work of a new design. The designs, depending upon the methods used, may be classified as follows: 3.1. Rational design. This type of design depends upon mathematical formulae of principle of mechanics.
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3.2. Empirical design. This type of design depends upon empirical formulae based on the practice and past experience. 3.3. Industrial design. This type of design depends upon the production aspects to manufacture any machine component in the industry. 3.4. Optimum design. It is the best design for the given objective function under the specified constraints. It may be achieved by minimizing the undesirable effects. 3.5. System design. It is the design of any complex mechanical system like a motor car. 3.6. Element design. It is the design of any element of the mechanical system like piston, crankshaft, connecting rod, etc. 3.7. Computer aided design. This type of design depends upon the use of computer systems to assist in the creation, modification, analysis and optimization of a design.
b) General Considerations in Machine Design Following are the general considerations in designing a machine component: 1. Type of load and stresses caused by the load. The load, on a machine component, may act in several ways due to which the internal stresses are set up. 2. Motion of the parts or kinematics of the machine. The successful operation of any machine depends largely upon the simplest arrangement of the parts which will give the motion required. The motion of the parts may be: (a) Rectilinear motion which includes unidirectional and reciprocating motions. (b) Curvilinear motion which includes rotary, oscillatory and simple harmonic. (c) Constant velocity. (d) Constant or variable acceleration. 3. Selection of materials. It is essential that a designer should have a thorough knowledge of properties of the materials and their behavior under working conditions. Some of the important characteristics xv
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of materials are: strength, durability, flexibility, weight, resistance to heat and corrosion, ability to cast, welded or hardened, machinability, electrical conductivity, etc.
4. Form and size of the parts. The form and size are based on judgement. The smallest practicable cross-section may be used, but it may be checked that the stresses induced in the designed cross-section are reasonably safe. In order to design any machine part for form and size, it is necessary to know the forces which the part must sustain. It is also important to anticipate any suddenly applied or impact load which may cause failure. 5. Frictional resistance and lubrication. There is always a loss of power due to frictional resistance and it should be noted that the friction of starting is higher than that of running friction. It is, therefore, essential that a careful attention must be given to the matter of lubrication of all surfaces which move in contact with others, whether in rotating, sliding, or rolling bearings. 6. Convenient and economical features. In designing, the operating features of the machine should be carefully studied. The starting, controlling and stopping levers should be located based on convenient handling. The adjustment for wear must be provided employing the various take-up devices and arranging them so that the alignment of parts is preserved. If parts are to be changed for different products or replaced on account of wear or breakage, easy access should be provided and the necessity of removing other parts to accomplish this should be avoided if possible. The economical operation of a machine which is to be used for production, or for the processing of material should be studied, in order to learn whether it has the maximum capacity consistent with the production of good work. 7. Use of standard parts. The use of standard parts is closely related to cost, because the cost of standard or stock parts is only a fraction of the cost of similar parts made to order. The standard or stock parts should be used whenever possible; parts for which patterns are already in existence such as gears, pulleys and bearings and parts which may be selected from regular shop stock such as screws, nuts and pins. Bolts and studs should be as few as possible to avoid the delay caused by changing drills, reamers and taps and also to decrease the number of wrenches required.
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8. Safety of operation. Some machines are dangerous to operate, especially those which are speeded up to insure production at a maximum rate. Therefore, any moving part of a machine which is within the zone of a worker is considered an accident hazard and may be the cause of an injury. It is, therefore, necessary that a designer should always provide safety devices for the safety of the operator. The safety appliances should in no way interfere with operation of the machine. 9. Workshop facilities. A design engineer should be familiar with the limitations of his employer’s workshop, in order to avoid the necessity of having work done in some other workshop. It is sometimes necessary to plan and supervise the workshop operations and to draft methods for casting, handling and machining special parts. 10. Number of machines to be manufactured. The number of articles or machines to be manufactured affects the design in a number of ways. The engineering and shop costs which are called fixed charges or overhead expenses are distributed over the number of articles to be manufactured. If only a few articles are to be made, extra expenses are not justified unless the machine is large or of some special design. An order calling for small number of the product will not permit any undue expense in the workshop processes, so that the designer should restrict his specification to standard parts as much as possible. 11. Cost of construction. The cost of construction of an article is the most important consideration involved in design. In some cases, it is quite possible that the high cost of an article may immediately bar it from further considerations. If an article has been invented and tests of handmade samples have shown that it has commercial value, it is then possible to justify the expenditure of a considerable sum of money in the design and development of automatic machines to produce the article, especially if it can be sold in large numbers. The aim of design engineer under all conditions, should be to reduce the manufacturing cost to the minimum. 12. Assembling. Every machine or structure must be assembled as a unit before it can function. Large units must often be assembled in the shop, tested and then taken to be transported to their place
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of service. The final location of any machine is important, and the design engineer must anticipate the exact location and the local facilities for erection.
Type of load. Motion of the parts. Selection of materials.
Form and size of the parts. Frictional resistance and lubrication. Convenient and economical features. Use of standard parts. Safety of operation. Workshop facilities. Number of machines to be manufactured. Cost of construction. Assembling. Figure 0-1 General Considerations in Machine Design
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CHAPTER (1) WASTE HEAT RECOVERY (WHRS) FOR REDUCTION OF FUEL CONSUMPTION & EMISSIONS
1
Introduction
Energy is an important mania for the economic development of any country. The energy requirement drastically increases in the recent years because of the rapid industrial growth. Nowadays worldwide concern is about the best ways of using the depletable sources of energy and of developing techniques to reduce pollution. This interest has encouraged research and development efforts in the field of alternative energy sources, cost-effective use of the exhaustible sources of energy, and the reuse of the usually wasted forms of energy. Moreover, as the fuel prices continues to escalate, the relevance of efficient energy management is apparent to companies everywhere, from the smallest concern to the largest multinationals. Many industrial processes covering most industrial sectors, use significant amounts of energy in the form of heat, which are rarely, used efficiently. The methods and techniques adopted to improve energy utilization will vary depending on circumstances, but the basic principles of reducing energy cost relative to productivity will be same. Thus, there is considerable scope for the use of heat exchangers and other form of heat equipment to enable waste heat to be recovered. Waste heat is generated by the way of fuel burning and then it is exhausted into the environment as a waste. The potential savings possible are greatest for the temperatures ranges from 200°C to 500°C. The developed countries are the pacesetters in energy consumption, discharging at the same time vast amounts of waste energy. The industry in these countries consumes the largest share of energy. Diesel engine is the one of the most efficient and versatile prime movers used in automobiles, stationary power generating plants, air compressors, construction machinery etc. Nearly about two- third of the heat generated by the engine is wasted through exhaust gas and cooling water and lost in to the surroundings. If some of this waste heat could be recovered, a considerable amount of primary fuel could be saved. Such a waste heat recovery would ultimately reduce the overall energy requirement and also the impact on global warming. 19
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Also, the recovered energy can be utilized to reduce the cost of waste disposal. Much effort has been expended during the past two decades to re-use the waste heat. But the energy lost in waste gases cannot be fully recovered. Waste heat is usually but not always characterized by low temperature. There are many methods through which this energy can be recovered and utilized. Waste energy can be recovered by the installations of special combustion equipment to utilize the unburned fuel, and the provision of heat recovery equipment to regain sensible and latent heat. Depending on the temperature level of the wasted heat and the proposed application, different heat exchangers can be employed to facility the use of recovered heat. The application of heat recovery should be physically close to the source of waste heat for maximum benefits from recovered energy. Energy storage is needed when there is a time span between energy recovery and use. The increasing fuel costs and diminishing petroleum supplies are forcing governments and industries to increase the power efficiency of engines. A cursory look at the internal combustion engine heat balance indicates that the input energy is divided into roughly three equal parts: energy converted to useful work, energy transferred to coolant and energy lost with the exhaust gases. There are several technologies for recovering this energy on a Heavy-Duty Diesel (HDD) engine, whereas the dominating ones are: o Mechanical turbocompounding. The Diesel engine is equipped with an additional power turbine. The power turbine is placed in the exhaust line and is mechanically coupled to the engine crankshaft via a gear train. o Electrical turbocompounding. The system consists of an electric motor/generator coupled by means of a turbocharger. The generator extracts surplus power from the turbine, and the electricity produced is used to run a motor assembled/fitted to the engine crankshaft. o Thermoelectric materials. The exhaust pipe contains a block with thermoelectric materials that generates a direct current, thus providing for at least some of the electric power requirements. o Rankine cycle. The system is based on the steam generation in a secondary circuit using the exhaust gas thermal energy to produce additional power by means of a steam expander. A special case of low temperature energy generation systems is the use of certain organic fluids instead of water in so-called Organic Rankine Cycle (ORC). This technique has the advantage compared with turbocompounding that does not have so an important impact on the engine pumping losses and with respect to thermoelectric materials that provides higher efficiency in the use of the residual thermal energy 20
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o Study of the engine waste energy sources the study of the engine waste energy sources. The main waste heat sources are: 1. The exhaust gas heat energy. 2. The EGR cooler. 3. The intercooler, where the Low-Pressure compressor outlet air is cooled. 4. The aftercooler, where the High-Pressure compressor outlet air is cooled also. 5. Engine block cooling water.
Table 1 summarizes the main results obtained in the configurations described in this paper. As show the table, the high-power increment is produced by the configuration with all the heat sources with a binary cycle. But the important increase in total heat transfer could be a problem to design the necessary heat exchangers. Thus, the best solution with lower heat transfer rates is the configuration with only the high temperature heat sources.
Table 1-1 Summarizes results
A method to analyze different possibilities to use waste energies in a Diesel engine is described in the present paper. This method involves estimating wasted energy values and uses this information to analyze the application of these energy sources in a bottoming Rankine cycle. Mechanical energy of a Diesel engine is about half of the total wasted energy. An
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important part of this wasted energy is used as thermal energy in intercoolers, radiators and exhaust gases expelled to the atmosphere. However, an important problem to recover these wasted thermal energies is the low temperature values of the available sources. Thus, it is difficult to achieve an acceptable efficiency using these sources. The configuration with all heat sources includes waste energy recovery in two different cycles (binary cycle). The main problem of this solution is the big size of heat exchanger surface necessary. The configuration with high temperature heat sources uses only high temperature waste energy sources in a water Rankine cycle. This solution is more realistic but reduces the energy recovery in comparison with the configuration with all heat sources. The external irreversibility’s of this Rankine cycle have been extensively studied in the present work. The most important conclusion in the studied cases, with ideal processes and when the engine dissipates more heat energy is that it can only recover between 8% and 9% of the total energy dissipated by the engine once internal irreversibility’s are also considered. Thus, because the characteristics of the residual heat in the studied engine operating point (maximum speed and maximum load), the resulting optimal working fluid is water. However, this type of engine, working in partial loads, have different operating conditions, meaning that the organic fluids (ORC) are more optimal for energy recovery. Therefore, the working fluid used will depend on engine operating conditions where the energy of these residual sources will be recovered. This paper is a study of maximum and these problems have not been addressed, leaving them for a future work.
Waste Heat Recovery Systems
2
Today several different WHRSs are readily available. Depending on the level of complexity acceptable to the owner and shipyard and the actual electrical power consumption on-board, it is possible to choose between the following systems: •
ST-PT – Steam Turbine-Power Turbine generator unit (Power turbine, steam turbine, gear and generator unit with single or dual pressure steam turbine)
•
STG – Steam Turbine Generator unit (Steam turbine, gear and generator unit, single or Dual steam pressure)
•
PTG – Power Turbine Generator unit (Power turbine, gear and generator unit).
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In the future, special variants and combinations of the above systems may be foreseen, particularly with the fulfilment of Tier III concerning NOx from 2016 and other future regulations.
Figure 2-1 Waste Heat Recovery system principles ▪
Description of the Waste Heat Recovery Systems
Power concept and arrangement the principle of the WHRS-tuned MAN B&W low speed diesel engine is that part of the exhaust gas flow is bypassed the main engine turbocharger(s) through an exhaust gas bypass. As a result, the total amount of intake air and exhaust gas is reduced. The reduction of the intake air amount and the exhaust gas amount results in an increased exhaust gas temperature after the main engine turbocharger(s) and exhaust gas bypass. This means an increase in the maximum obtainable steam production power for the exhaust gas fired boiler – steam, which can be used in a steam turbine for electricity production. Also, the revised pressure drops in the exhaust gas bypass, which is part of the WHRS, can be utilized to produce electricity by applying a power turbine. As mentioned before, a WHRS consist of different components, and may wary as a standalone installation or a combined installation Choosing a system for a project depends on the
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power demand onboard the ship (electrical load at sea), the ship’s running profile (hours at different main engine loads at sea), the acceptable payback time for the proposed WHRS solution based on the running profile and the space available on the ship, among others. A very important part of selecting the best WHRS for a ship project is choosing the best suited propulsion power and rpm for the ship – biggest possible propeller – so as to ensure the lowest possible fuel consumption for the basic performance of the ship ,In many cases, WHRS will be able to supply the total electricity need of the ship as a standalone power source, but it can also run in parallel with a shaft generator, shaft motor and auxiliary diesel generating sets. This type of advanced power system requires an advanced power management system (PMS), with which the MAN Diesel & Turbo engine control system is designed to communicate. Particularly for container ship designs, WHRS has found its place where it contemplates a technological step forward in lowering fuel consumption and CO2 emissions of the ship, but the interest for WHRS solutions is spreading to other ship types with the aim of re-duking total fuel costs, ship EEDI and emissions. 2.1
Power turbine and generator (PTG) The simplest and cheapest system consists of an exhaust gas turbine (also called a power
turbine) installed in the exhaust gas bypass, and a generator that converts power from the power turbine to electricity on-board the ship. For power turbine solutions, the main engine receiver
Figure 2-2 Schematic diagram of the WHRS-PTG system
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will be equipped with two exhaust gas connections, one for engine exhaust gas by-pass (EGB) and one for the power turbine. The connection for the power turbine must typically be larger as the power turbine unit typically is arranged several meters away from the main engine in the engine room. The exhaust gas by-pass with exhaust gas bypass control valve and orifice is part of the engine delivery and will be tested at the engines shop test the power turbine and the generator are placed on a common bedplate.
TCS-PTG stands for Turbo Compound –
System
Power
Turbine Generator and is an MAN Diesel & Turbo
product
The
power turbine is driven by part of the exhaust gas
flow
bypasses
which the
turbochargers.
Figure 2-3 WHRS system turbine generator unit The power turbine produces extra output power for electric power production, which depends on the bypassed exhaust gas flow amount. The PTG WHRS solution can both be a standalone and / or parallel running electric power sourcing for the ship. The exhaust gas bypass valve will be closed at an engine power lower than about 40% SMCR, down to an engine load point where power utilization for the power turbine is economical desirable, which stop when the ancillary engine blower(s) start. Using a TCS-PTG WHRS solution will provide a 3-5% recovery ratio, depending on the main engine size. increasing the exhaust gas temperature before the boiler without using a power turbine. When applying the steam turbine (ST) as a stand-alone solution, the exhaust gas bypass stream is mixed with the exhaust outlet from the turbocharger(s), increasing the exhaust gas temperature before the boiler inlet. When part of the exhaust gas flow is bypassed the turbocharger, the total amount of air and gas will be reduced, and the exhaust gas temperature after the turbocharger and bypass will increase. This will increase the obtainable steam production power for the exhaust gas fired boiler. By installing a steam turbine (often called a turbo generator), the obtainable steam production from the exhaust
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boiler system can be used for electric power production. The steam turbine is installed on a common bedplate with the generator in the same manner as the power turbine and the generator. Like the PTG design, the STG solution can function both as a stand-alone and as a parallel running electric power source for the ship – depending on the actual demand for the particular ship design. Using a WHRS STG system, it will be possible to recover some 5 to 8%, depending on the main engine size, engine rating, and ambient conditions
2.2
Steam turbine, power turbine, and generator (ST-PT) If
the
electric
power demand on the ship is very high, e.g. a container
ship,
the
power turbine and the steam turbine can be built together to form a combined system. The power turbine and the steam turbine are built onto
a
bedplate
common and,
via
Figure 2-4 Full WRHS system and power turbine unit
reduction gearboxes, connected to a common generator.
The power output from the power turbine can be added to the generator via a reduction gear with a special clutch. However, first the steam turbine will start at 30 – 35% SMCR main engine power followed by the power turbine which starts power production at 40 to 50% SMCR. The combined WHRS ST & PT schematic diagram, which shows a system that, in many conditions, reduces the fuel costs of the ship considerably by being able to cover the total electric power needs in many conditions onboard the ship. Otherwise, a shaft motor / generator (PTI/PTO) connected to the main engine shaft could be an option, see Fig. 8, making it possible to add either electric power to the ship grid if needed, or to boost propulsion by supplying the electric power to the PTI.
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Figure 2-5 Schematically diagram of the WHRS ST-PT system Selecting the full WHRS – combining both steam and power turbines – some 8-11% power can be recovered, depending on the main engine size, engine rating and ambient conditions. Choosing the system most suitable for a specific ship project requires careful evaluation based on requirements concerning fuel efficiency, arrangement restrictions, emission requirements, operational profile for the ship, payback time, etc. The project conditions vary from case to case as the opinion on acceptable payback time differs among shipowners. Still, the below guidelines may be very useful when evaluating a new ship project and the potential for utilizing WHRS advantages. As a rule of thumb, we recommend the following: 1. Main engine power > 25,000 kW → Combined ST and PT 2. Main engine power < 25,000 kW → PTG or STG (e.g. with super heater) 3. Main engine power < 15,000 kW → PTG or ORC (Organic Rankine Cycle)
2.3
Exhaust gas boiler and steam systems The exhaust gas boiler and steam turbine systems analyzed in this paper are based on the
single and dual steam pressure systems. A higher number of pressure levels is possible, as used within power plant technology, but for marine installations single and dual pressure is the normal standard.
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2.3.1 Single-pressure steam system The
simple
single-pressure steam system only utilizes the exhaust gas heat and the corresponding temperature/heat transmission diagram. The steam drum from the oil-fired boiler can also be used instead of a separate steam drum.
Figure 2-6 Process diagram pressure exhaust gas boiler system
Figure 2-7 Temp. transmission diagram for dingle pressure steam sys.
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The single steam pressure system is less complex and easy to operate, but the possible efficiency of the total steam circuit (exhaust boiler and steam turbine) will be less than the more used dual pressure steam system.
2.3.2 Dual-pressure steam system When using the dual-pressure steam system, it is not possible to install an exhaust gas low-pressure preheater section in the exhaust gas boiler, because the exhaust gas boiler outlet temperature would otherwise be too low and increase the risk of wet (oily) soot deposits on the boiler tubes. Too low an exhaust boiler outlet temperature may result in corrosion in the exhaust piping when running on normal HFO with Sulphur content. The more complex dual-pressure steam system, therefore, needs supplementary waste heat recovery (WHR) sources (jacket water and scavenge air heat) for preheating feed water, which will increase the obtainable steam and electric power production of the WHRS. If no alternative waste heat recovery sources are used to preheat the feed water, the low pressure (LP) steam may be used to preheat the feed water, involving an about 16% reduction of the total steam production. The available superheated steam used for the steam turbine is
Figure 2-8 Temp. transmission diagram for the dual pressure steam system
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equal to the surplus steam after deduction of the saturated steam needed for heating services. The exhaust gas boiler must be designed in such a way that the risk of soot deposits and fires is minimized. For tube type exhaust boilers, which is the boiler type normally used for WHRS, it is further recommended gas to be bypassed the exhaust boiler when the engine load is below 30% SMCR, or in case of other malfunctions of the steam system. Today, the dual steam pressure system is the standard on large container ships applying WHRS.
Figure 2-9 Process diagram for the dual pressure exhaust gas boiler system
Figure 2-10 WHRS recovery ratios 30
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Organic Rankine Cycle (ORC) ORC is considered a way of converting different kinds of low temperature energies such
as solar, geothermal, biomass and thermal energy of exhaust gases into electrical energy. Several studies have examined Rankine cycles for exhaust gas heat recovery in vehicle applications. For instance, Thermo Electron Corporation tested a Diesel-Organic Rankine compound engine on Class 8 trucks. The application in a specific vehicle requires a redesigned system to fit all system components. The additional vehicle mass and system cost need to be determined to show its economic feasibility.
2.4.1 Experimental Setup and IC engine model The engine studied in this article is a 12 liter two-stage HDD engine. The selection of a two-stage engine for this work has been done in order to keep maximum dynamic capabilities of the resulting configuration once coupled with the bottoming cycle system; transients of this engine, without a bottoming cycle, have been experimentally analyzed in The engine model has been fitted using experimental data at full load conditions with different engine speeds. Some of these steady points are given in Table 1.
2.4.2 Configuration with all waste heat sources. A single cycle. The performance of a bottoming Rankine cycle can be evaluated under diverse working conditions for the pre-selected working fluids (R-245fa, FC72, FC87, HFE7000, HFE7100, R236fa, RC-318 and water). This pre-selection was performed by means a study similar to studies that can be found in the literature on selection of working fluid for Rankine cycles [28]. The analysis assumes the following: steady state conditions, no pressure drop in the vaporizer and condenser, and isentropic efficiencies for the expansion machine and pump of 100%. Regarding the implementation of these configurations in the industry applications, an appropriated expander machine must be selected to obtain an acceptable efficiency and to consider the most important internal irreversibility’s of these cycles. For this objective, the Japiske Turbine Chart or Barber-Nichols Turbine Chart can be utilized to approximate the most effective expander machine. A parametric-iterative method has been employed for choosing the optimum working fluid and to obtain the maximum working fluid mass flow for each investigated vaporizer and superheater temperatures.
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Aiming to recover all the available waste heat sources, the following criteria have been considered for the selection of the bottoming cycle working fluid: Pressure ratio in the expansion machine must be lower than 25 to achieve an efficient expansion process. The studied cycles must keep a minimum temperature difference between the working fluid and the engine heat sources to guarantee minimum irreversibility’s in the heat transfer process. This difference is usually fixed to 10ºC. This is called Pinch-Point and it can be presented along with the fluid evaporation process. This point is usually denoted as "PP". The optimum points for each studied working fluid. A similar work output (around 27 kW) and cycle efficiency (around 6%) are obtained at similar working conditions for almost all investigated organic fluids. Therefore, the R245fa was selected as the working fluid in ORC with low temperature heat sources, due to its reasonable cycle output work and mild condensation pressure at 50ºC. This study becomes an unusual study. Generally, in conventional ORC studies, the researcher seeks a single heat source with a certain temperature and mass flow to analyze the best Rankine cycle, in order to maximize the obtained power. But in this study, from different heat sources selected previously, which correspond to the wasted energy sources of the IC engine, the main objective is to find the Rankine cycle that best fits to these sources. Considering that some of these sources have the input and output temperatures fixed. This parametric study was made with a cycle which has a condensing temperature of 40 º C. If 70 º C is considered as the evaporating temperature and the water is superheated to temperatures around 170 º C, the water provides better results than the R245fa. This result is because the R245fa in these conditions cannot be superheated above 82 ° C. The reason is the different pinch point restrictions that exist in the heat exchange between the different waste heat sources. Sometimes, these restrictions do not allow the energy recovering from all heat sources considered in the study (Top graphs) and they are very different i.e.: The thermal source with higher temperature is the EGR gases, which is cooled from 509 ° C to 222 ° C, and the thermal source with lower temperature is the cooling water, which is typically cooled in the car radiator from 85 º C to 80 º C, although this source gives more power (205kW), due to high water flow and its specific heat. Due to these peculiarities of the considered heat sources, the optimal working fluid obtained does not correspond to an organic fluid, as initially could be expected. However, due to the low temperature difference between the vaporizer and condenser, imposed by the initial restrictions, the achieved work output is not significant compared to the total waste heat. Shows how the cycle using R245fa has better efficiency and output power than 32
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water in the low evaporation temperature zone. On the contrary, using water as a working fluid permits complete energy recovery at higher superheater temperature and also gives higher efficiency and power output. The main drawback is the low evaporation and condensation pressures when the water cycle operates with a temperature lower than 100ºC. Showing that the Rankine cycle has a significant effect on total power compared with the Reference engine system (311 kW of the engine plus 31 kW provided by the cycle). This increment is equivalent to a 10% of power increment over the reference configuration. One of the biggest drawbacks of this configuration would be the important increase in the total heat transfer processes (868 kW vs 357 kW in the reference engine configuration) and consequently in the size of the heat exchangers.
2.4.3 Configuration with all heat sources. Binary Cycle In the previous section, R245fa and water have been initially selected as the best solution for low and high evaporation temperatures respectively. For this reason, the use of two coupled cycles (binary cycle) tries to obtain the maximum power from all the considered heat sources. The iterative-parametric study is performed in order to accomplish these criteria. The fluid tables are used in order to obtain the optimal combination of: maximum temperature cycle, evaporation and condensation temperature and mass flow. The optimal solution needs an agreement between maximum temperature and the working fluid mass flow to obtain the greatest power output. The top left graph represents the different heat transfer processes taking place in the high temperature cycle (Water cycle). Heat sources are represented by the thin lines. The black bold line represents the working fluid evaporation process. The graph shows that the water is heated from 137ºC to 220ºC by the exhaust gas heat source. At this point, the water evaporates at constant pressure receiving heat from the exhaust gases and the EGR cooler. The rest of the EGR cooler heat is used for heating the steam up to 470ºC. The superheated steam will then be expanded through the turbine. The working fluid used in the low temperature cycle must be an organic fluid. In the previous section, the R245fa has been selected as the best option for this kind of cycles and it is used in this case. In this cycle, the heat absorbed by the R245fa in the beginning of the evaporation process is the heat released by the non-recirculated exhaust gases energy, the high temperature cycle condenser, intercooler, cooling water and the aftercooler, as shown in bottom graph. In this case, the heat sources have temperatures between 195ºC and 80ºC. The evaporation temperature must be lower than the temperature of cooling water to allow heat 33
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transfer between this heat source and the working fluid cycle. Thus, evaporation temperature is fixed in 71ºC in the R245fa cycle and this fluid enters in the expansion machine from saturated steam conditions. The heat transfer of each source is represented in the temperature vs transferred heat diagram in the top right side, showing the critical point (pinch point) in the low temperature vaporizer (PP2). The design criteria used at PP2 is the same that was used at PP1. The condensation temperature in the low temperature cycle is fixed at 50°C to ensure the cooling of the condenser with the atmosphere at 40 °C.
The binary cycle has a significant effect on the total power compared to the Reference engine system. The binary cycle produces a mechanical power of 59 kW (35 kW in the Top Rankine Cycle plus 24kW in the Bottom Organic Rankine Cycle). Clearly, 59 kW, which is about 19% of effective power, can be stated as an ideal figure since only external irreversibility’s have been considered during binary cycle analysis. In addition, as in the previous configuration, one of the problems is an important increase of the dissipated heat in the heat-exchangers, since the heat transferred was increased to almost 170 % by the two thermodynamic cycles. (938 kW in binary cycle configuration versus 357 kW in the reference configuration).
Configuration with high temperature heat sources In the previous solutions, many heat sources with different temperature ranges have been considered. That solution provided a considerable increase in total engine efficiency, but it must deal with important technical difficulties due to the heat control system of all the heat transfer processes and the low temperature of some sources. Consequently, a configuration with only high temperature heat sources, therefore using less heat sources, has been also investigated in order to obtain a more realistic technical solution. The EGR cooler, exhaust gases and Aftercooler are the best suitable sources for recovering heat considering their high temperatures. Different working fluids and different cycles have been studied using the maximum output power as a goal. The result of these studies gives a water Rankine cycle as the best option, since it is possible to reach a superheat temperature of 500ºC. The same iterative-parametric study, done previously, has been carried out in this case, with the same objective as for the configuration with all heat sources. Figure 8 shows the main variables of this parametric study. The water cycle has been optimized and this cycle has a 143°C vaporization temperature, a superheating temperature up to 485°C and regeneration. The
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condensation temperature is 50ºC due to the heat transfer and the pinch-point criteria. The right striped area indicates the Rankine cycles in which the expansion ratio is higher than 25.
The top graph shows the evaporation process between the working fluid and the three heat sources. This figure confirms how the critical point is again the pinch-point (PP3). (bottom graph) shows all the high temperature heat sources used in the Rankine cycle. Only a small part of the power of exhaust gases and aftercooler cannot be used in the cycle, due to their low temperatures. This configuration with high temperature heat sources produces an increase in the output power about 46 kW instead of the 59 kW that was achieved using the configuration with all heat sources. Although the heat dissipated in the configuration with high temperature heat sources is lower than in the configuration with all heat sources, this still needs a heat exchange larger than the exchanger used in the reference engine. However, it would allow the installation of the configuration with high temperature heat sources in an HDD engine since space requirements are not so large.
2.5
waste heat recovery from diesel engine exhaust using phase change material The exhaust gas from the diesel engine exhausted to the atmosphere as waste carries
approximately 30% of the heat of combustion. By providing proper Waste Heat Recovery System (WHRS), a considerable amount of heat can be saved. In the present study, the shell and tube heat exchanger and Thermal Energy Storage System (TESS) contained Paraffin Phase Change Material (PPCM) incorporated with a diesel engine system to extract heat from the exhaust gas. The performance of the heat exchanger and thermal storage tank were investigated under the different loading condition. It is found that 86.45 kJ/kg of heat energy extracted from the heat exchanger and 0.54 kW of heat energy is saved at full load condition; it is nearly 7% of fuel power is stored as heat in the storage system, and the water can be utilized for suitable applications which are available reasonably at higher temperature.
2.5.1 Experimental Setup and procedures The main objective is to extract heat from the exhaust gas of a diesel engine and to store it in the thermal storage tank. This could be achieved by the heat exchanger and the thermal Storage System separately. The heat exchanger coil is not embedding inside the storage tank due to the very low convective heat transfer coefficient for gases, because of this larger surface
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area is needed on the gas side for better heat transfer. Also due to poor thermal conductivity, the PCM cannot be packed directly inside the storage tank, which varies the resistance for heat transfer during charging and discharging, so that the PCM encapsulated in separate containers inside the storage tank to store the heat. When the PCM solidifies on the convective heat transfer surface inside the storage tank, the solidified layer itself act as an insulator and as the thickness of the layer increases with respect to time, the resistance for heat transfer increases between the liquid PCM and the HTF in the storage tank, in turn decreases the heat transfer rate and causes a non-uniform rate of discharging characteristics in the storage tank. The experimental setup is consisting of six cylinders Ashok Leyland diesel engine, heat recovery heat exchanger and the thermal storage system.
(B)
(A)
Figure 2-11 Schematic diagram of the experimental setup
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2.5.1.1 Engine Setup The engine used for this study is a four stroke, water cooled, six-cylinder diesel engine. The rated power of the engine is 61kW at 1500rpm. The engine is mounted on the bed with suitable connections for fuel and cooling water supply. The engine is coupled with an electrical dynamometer to vary the load on the engine.
2.5.1.2 Heat Recovery heat Exchanger In all energy conversion methods due to thermodynamic constraints and other reasons, large quantity of heat available in the exit streams discharge into the atmosphere without proper utilization and these results in a major loss in thermal efficiency. Air preheater using WHRS and co-generation are successful techniques to improve the overall thermal efficiency of a system to certain extent. By the efficient implementation of suitable WHRS, the exit stream energy can be stored and utilize and there by improve the overall thermal efficiency. The schematic diagram of the heat recovery heat exchanger is illustrated in fig (A) consists of a vertical cylindrical shape heater core made of mild steel, with a circumference of 300 mm and an active length of 450 mm. A copper tube of size 10 mm is wound over this heater core at gradual intervals across its length. The copper tube is connected into the thermal storage tank that is filled with water and phase change material. The water inside the copper tube circulated as natural circulation. The above said setup is fitted in the exhaust pipe of the engine to extract the waste heat from engine exhaust gas using water as heat transfer fluid.
2.5.1.3
Thermal Storage Tank
Thermal storage units have received greater attention in solar and waste heat recovery thermal applications because of the large heat storage capacity and their isothermal behavior during charging and discharging process. The major technical constraint, which prevents successful implementation of heat recovery system, is intermittent and time mismatched demand and availability. In order to overcome the above constraint WHRS integrated with thermal storage unit can be adopted. Thermal energy storage provides one practical means of storing energy during availability and use this energy when need arises. Fig (B) shows the schematic diagram of the thermal storage system consists of stainless steel vessel of diameter 250 mm and height 300 mm and it is well insulated by using fiber coir
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to prevent heat radiation to the surroundings. It contains water as the sensible heat material and paraffin as the latent heat material. Hence it is called combined sensible and latent heat storage system. The water also acts as the heat transfer fluid to extract the heat from the exhaust gas. The tank is filled with 40 Nos. of spherical containers made of Low Density Polyethylene (LDPE) having a diameter of 50mm whose melting Point is 110oC and density 0.910 – 0.940 g/cm3, each spherical container contains approximately 100 grams of paraffin phase change material.
Table 2-1 Property of paraffin phase change material
2.5.2
Results and discussion The results of the diesel engine operated at various load conditions were studied. The
exhaust gas from the diesel engine carries approximately 25 to 30% of the heat of combustion. In this study, many attempts have been made to extract the maximum possible heat energy from the exhaust gas through a shell and tube heat exchanger and to store this heat energy in TES tank filled with spherical LDPE 2.5.2.1
Performance of heat recovery heat exchanger.
The temperature variation of the exhaust gas and the water at the inlet and outlet of the HRHE with respect to time for different engine load conditions (25%, 50%, 75% and full load)
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Figure 2-12 Temp. variation of the exhaust gas and the water at the inlet and outlet of the HRHE at 25% load.
At 25% load, a constant temperature around 60°C is obtained after 90 minutes and this duration decrease with increase in load and also the maximum temperature of water attained 98°C after 240 minutes. This duration also decreases when the load of the engine increases
Figure 2-13 Temp. variation of the exhaust gas and the water at the inlet and outlet of the HRHE at 50% load. At 50% load, a constant temperature around 60°C is obtained after 80minutes and the maximum temperature of water attained 98°C after 210 minutes.
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Figure 2-14 Temp. variation of the exhaust gas and the water at the inlet and outlet of the HRHE at 75% load. At 75% load, a constant temperature of 60°C is obtained nearly at 70minutes and the maximum temperature of water reached 98°C at 180 minutes.
Figure 2-15 Temp. variations of the exhaust gas and the water at the inlet and outlet of the HRHE at full load. At full load, a constant temperature of 60°C is obtained at around 65minutes and the maximum temperature of water attained 98°C at 150 minutes. From the graph, as the load on the engine increases the exhaust gas temperature also increases accordingly. However, initially during starting of the engine and auxiliaries will absorb a part of the incremental heat till the system attains steady state. Thereafter the temperature of exhaust gas coming from the engine will be approximately at a constant high temperature. At all the loading conditions the
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temperature difference of the water and gas outlet is same, and the slope decreases when the temperature of the water reaches nearly 60°C and further increases gradually.
Figure 2-16 shows the variation of the heat extraction rate from the exhaust gas through the HRHE evaluated at different loads. The average heat extracted values at 25%, 50%, 75% and full load condition are 0.68kJ/kg, 51.84kJ/kg, 70.92kJ/kg and 86.45kJ/kg respectively. At full load condition the heat extraction is maximum when compared to all other engine load conditions due to high heat release rate from the engine. From the figure it has been observed that at all the loads, the heat extraction rate decreases as time increases. It is due to the increasing temperature of the water at the inlet of HRHE which reduces the average temperature difference between the exhaust gas and the water.
2.5.2.2 Performance of the Thermal Energy Storage Tank
Figure 2-17 Heat Energy saved in the storage tank for different loading conditions
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Heat energy stored in the storage tank, it is seen from the above graph that the heat energy storing capacity increases while load of engine increases. The total heat stored in the TES tank is 4863kJ in which the heat stored in the water is 4003 kJ with a temperature raise of 65°C (98– 33°C) and heat stored in the PPCM is 860 kJ. The total heat storage capacity in the PPCM is due to its sensible heat (272 kJ) and latent heat (588 kJ). In the storage system the contribution of latent heat is only 12% of the total heat storage capacity. When the storage tank attains 98°C, the total energy stored in the storage tank is 4863 kJ with respect to environment. Though the energy stored is same at all load conditions, it is observed that the duration of charging is 240 min at 25% load and it decreases to 210 min, 180 min and 150 min, respectively for 50%, 75% and full load conditions. This shows that there is a variation in the charging rate. The energy saving at 25%, 50%, 75% and full load condition are 0.337kW, 0.386kW, 0.450kW and 0.540kW respectively which is evaluated by,
2.5.3 Summary of phase change systems The exhaust gas of a diesel engine carries a considerable amount of heat and this energy can be recovered efficiently by using HRHE and TES tank. A suitable waste heat recovery system with a TES tank can store heat energy and this energy can be utilized for many applications like process heating etc., in industries. In the present study a shell and tube heat exchanger and a PPCM based TES tank were designed and fabricated and tested with a diesel engine. The investigation has shown the following conclusions: Nearly 4–7% of total heat (that would otherwise be gone as waste) is recovered with this system. The maximum heat extracted using the heat exchanger at full load condition is around 86.45kJ/kg. The maximum energy saved at full load condition in the thermal storage tank is 0.540 kW. The presence of LDPE it conducts heat uniformly and found uniform temperature throughout the TES tank. The percentage of heat recovered can be increased further by increasing the surface area of the HRHE. The charging efficiency of the storage tank and the percentage of energy saved can be improved further with proper insulation and also increasing the Nos. of LDPE containers.
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3
3.1
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Calculation of double acting diesel engine
Diesel fuel
Table 3-1 Double acting calculations for diesel fuel
3.2
𝒎.𝒇
0.3653
kg/s
𝑸𝒂𝒅𝒅
15601.66
Kw
𝒎.𝒆𝒙
17.5
kg/s
𝑸𝒆𝒙
3962.82164
Kw
𝑸𝒂𝒇𝒕𝒆𝒓 𝒕𝒖𝒓𝒃𝒐
967.82164
Kw
𝑸𝒂𝒄𝒕𝒖𝒂𝒍
919.43
Kw
Steam
Table 3-2 Double acting calculations for steam engine
4
𝑯𝒄𝒍𝒆𝒂𝒓𝒂𝒏𝒄𝒆
8.85
Cm
𝒓
3.5
_____
𝑷𝒎
97525
N/m2
𝒗𝒐𝒍
0.066727
m3
𝒎.𝒔𝒕𝒆𝒂𝒎
3.076
Kg/s
𝒎.𝒔𝒕𝒆𝒂𝒎 𝒂𝒄𝒕𝒖𝒂𝒍
4.3
Kg/s
𝑸𝒃𝒐𝒊𝒍𝒆𝒓
4.4
Kw
𝑽𝒄𝒖𝒕 𝒐𝒇𝒇
1.06*10-4
m3
𝒎.𝒔𝒕𝒆𝒂𝒎 𝒂𝒄𝒕𝒖𝒂𝒍
4.122*10-3
kg/s
Emission Effects of using WHRS
Based on an HFO fuel saving of 3,555 tons per year (with 3% Sulphur content), the installation of a WHRS on a large container ship will save the environment for the following emission amounts:
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• CO2 emission saving per year: 11,260 tons • NOx emission saving per year: 319 tons • SOx emission saving per year: 214 tons • Particulates saving per year: 29 tons
4.1
Limitations of parameters and input values assumed for steam turbine cycle calculations Limitations of values of steam cycle parameters result from strength, technical and
durability conditions of particular elements of the subsystem as well as from design and economic factors. The calculations of the steam subsystem of the ship combined power system were performed under the assumptions and limitations given below. The temperature difference between exhaust gas temperature and that of live steam, Δt, for waste heat boilers of marine application, was assumed Δt = 15°C. The value of the „pitch point” recommended by the firm MAN B&W for ship boilers is equal to δt = δt1 = δt2 ≈ 10°C. The limit steam dryness ratio behind the steam turbine was assumed xlimit = 0.88. For ship outboard – water – cooled condensers the firm MAN B&W recommends assuming the pressure inside the condenser equal to pk = 0.065 bar. Temperature of water supplying the boiler should not be lower than 120°C, at the Sulphur content greater than 2%. The reason is that outer surface of heater pipes from the exhaust gas side has its temperature higher by 8 ÷ 15°C than that of the supply water, and that materials of a higher resistance against acid corrosion are applied; hence for the calculations it was assumed that the supply water temperature cannot be lower than tFW > 120°C. It was also assumed that the exhaust gas temperature at outlet from the boiler must be higher by 15°C than that of supply water, i.e.: texh > tFW + + 15°C. Every ship combusting the heavy oil for propulsion uses a large amount of heat to prepare the fuel. For the considered containership’s power plant, the mass steam flow rate for power plant use in compliance with the MAN B&W recommendations was assumed. The flow rate was made greater by the steam flow rate necessary for ship living purposes, which was estimated to be mss = 2000 kg/h of saturated steam. The steam pressure for living purposes should be kept within the range pss = 7 ÷ 9 bar. In the assumed scheme of steam turbine cycle, the pressure of the steam for living purposes is equal to that of the boiler’s lowpressure cycle: pI = pss. The temperature in the cooling box was assumed tss = 50°C,in compliance with the recommendation. 44
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CHAPTER (2) SPECIFIC FUEL CONSUMPTION
5
Introduction
From the early 19th century until the third quarter of the 20th century, steamships crossed the seven seas, gradually eliminating sailing ships from commercial shipping. In the second half of the 20th century, the motor ship started to dominate. The history of the diesel engine began in 1892 with Rudolf Diesel and twenty years later, the first four-stroke marine diesel engine ships were operational. Around 1930, two-stroke designs took a strong lead as ships became larger and faster. Between World War I and World War II, the share of marine engine-driven ships increased to approximately 25 percent of the overall ocean-going fleet tonnage. A series of innovations of the diesel engine followed, which made it possible to use heavy fuel oil in medium speed trunk piston engines, pioneered by the MV The Princess of Vancouver. In the mid-1950s, high alkalinity cylinder lubricants became available to neutralize the acids generated by the combustion of high Sulphur residual fuels, and wear rates became comparable to those found when using distillate diesel fuel. Diesel ships using residual fuel oil gained in popularity and in the second half of the 1960s, motor ships overtook steamships, both in terms of numbers, and in gross tonnage. By the start of the 21st century, motor ships accounted for 98 percent of the world fleet. Marine engines have also found their way into the power industry.
6
6.1
Crude Oil
Crude oil field formed The generally accepted theory is that crude oil was formed over millions of years from
the remains of plants and animals that lived in the seas. As they died, they sank to the seabed, were buried with sand and mud, and became an organic-rich layer. Steadily, these layers piled up, tens of meters thick. The sand and mud became sedimentary rock, and the organic remains
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became droplets of oil and gas. Oil and gas passed through the porous rock and were eventually trapped by an impervious layer of rock, collecting at the highest point. The formation of an oil/gas field requires the presence of four geological features: •
Source rock: contains suitable organic matter, which, under the conditions of heat and pressure, produces hydrocarbons
•
Reservoir rock: a porous layer of rock in which the hydrocarbons are retained
•
Cap rock: a rock or clay, which prevents the hydrocarbons from escaping
•
Trap: a rock formation bent into a dome or broken by a fault which blocks the escape of the hydrocarbons either upward or sideways
Most importantly, these four factors must occur at the right time, place and in the right order for oil and gas to be formed and trapped. Currently, successful petroleum exploration relies on modern techniques such as seismic surveying. The fundamental principle of seismic surveying is to initiate a seismic pulse at or near the earth’s surface and to record the amplitudes and travel times of waves returning to the surface after being reflected or refracted from the interface(s) on one or more layers of rock. Once seismic data has been acquired, it must be processed into a format suitable for geological interpretation and petroleum reservoir detection.
6.2
Composition and classification of crude oil Crude oil is a mixture of many different hydrocarbons and small amounts of impurities.
The composition of crude oil can vary significantly depending on its source. Crude oils from the same geographical area can be very different due to different petroleum formation strata. Different classifications of crude oil are based on: I.
Hydrocarbons: 4. Paraffinic crudes 5. Naphthenic crudes 6. Asphaltene (aromatic) crudes Each crude oil contains the three different types of hydrocarbons, but the relative
percentage may vary widely. For example, there is paraffinic crude in Saudi Arabia, naphthenic crude in some Nigerian formations and asphaltene crude in Venezuela.
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American Petroleum Institute (API) gravity: The lower the density of the crude oil, the higher its API gravity. A higher API gravity means that the crude contains more valuable lower boiling fractions.
III.
Sulphur content: The ever-growing concern for the environment and the impact on refining cost calculations are the basis for this classification. •
Low Sulphur crude
•
High Sulphur crude
Figure 6-1 Crude oil distillation
6.3
Crude oil refining and stocks for marine fuel blending Petroleum refineries are a complex system of multiple operations. The processes used at
a given refinery depend upon the desired product slate and characteristics of the crude oil mix. Today, complex refining has a definite impact on the characteristics of marine diesel and intermediate fuel oil (IFO) bunker fuel.
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6.3.1 Typical refining schemes and the influence on marine fuels 6.3.1.1 Straight run refinery Atmospheric crude distillation and further refining of distillates:
6.3.1.2 Straight run stocks for marine fuel blending Light diesel, heavy diesel, and straight run residue 6.3.1.3 Straight run marine gasoil and distillate marine diesel (MDO) Marine gasoil and distillate marine diesel oil (MDO) are manufactured from Kero, light, and heavy gasoil fractions. For DMC distillate marine diesel up to 10–15%, residual fuel can be added.
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7.1
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Fuel Oil
Fuel oil applications All fuel oil applications create energy by burning fuel oil. Fuel oil combustion (oxidation
reaction) releases a large amount of heat, which can be used for steam generation, for example, in steam turbines. The high volume (pressure) of the combustion gases can be used to drive an engine, or (less frequent for HFO, but widespread for gasoil) a gas turbine. When fuel oil is burned, an amount of heat is released, which is defined by the specific energy (international unit MJ/kg) of the fuel. Thermal plants use this heat to generate steam, which then drives steam turbines, thus providing mechanical energy that can be used for propulsion or to be converted into electrical energy. For marine engines and gas turbines, mechanical energy provided by the combustion gases is used either directly for propulsion or converted into electrical energy for power plants. For larger installations, cost efficiency optimization and environmental constraints led to the introduction of co-generation. In cogeneration, some of the electrical energy lost is used to generate low-pressure steam, suitable for a wide range of heating applications.
7.2
Fuel specifications Different types of fuel oil applications and environmental considerations have led to
different types of fuel oil specifications. These are much more demanding than the original fuel oil n° 6 or Bunker C requirements when all heavy fuel was used for thermal plants and steam turbines. Emission standards for thermal plants can vary widely, depending on the geographical area. Since all emitted 𝑆𝑂2 originates from Sulphur in the fuel, emission standards on 𝑆𝑂2 automatically limit the Sulphur content of the fuel, except for large combustion plants, where the standard can be economically met by flue gas desulphurization. In the late 1960s, marine diesel engines were the primary means of ship propulsion. Through the late 1970s, marine engine heavy fuel oil grades remained identified solely by their maximum viscosity. This worked well with heavy fuel originating from atmospheric refineries. Fuel-related operational problems arose with the generalized upgrading of refinery operations in the second half of the 1970s from straight run to complex refining. 1982 saw the publication of marine fuel specification requirements by the British Standard Organization (BS MA 100), and by CIMAC (Conseil International de Machines à Combustion).
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An international ISO standard has existed since 1987: ISO 8217. The stated purpose of ISO 8217 is to define the requirements for petroleum fuels for use in marine diesel engines and boilers, for the guidance of interested parties such as marine equipment designers, suppliers and purchasers of marine fuels. These specifications are regularly revised to accommodate changes in marine diesel engine technology, crude oil refining processes and environmental developments. The most important specifications to ensure reliable engine operation with fuel originating from complex refining are: •
Maximum density limit: Important for classical purifier operation and to ensure satisfactory ignition quality for low viscosity fuel grades
•
Maximum Al+Si limit: In a complex refinery, HCO is used as a blending component. Mechanically damaged aluminum silicate catalyst particles of the catalytic cracker are not completely removed from the HCO stream, and are found back in mg/kg amounts in heavy fuel blended with HCO. In order to avoid abrasive damage in the fuel system onboard the vessel, it is necessary to limit the amount of Al+Si to a level, which can be adequately removed by the ship’s fuel cleaning system.
•
Maximum total potential sediment limit: The stability of asphaltenes is deteriorated by the visbreaking process, and instability problems can cause fuel purification and filter-blocking problems, hence the need for a specification to ensure adequate fuel stability.
A less widespread application of heavy fuel is found in heavy-duty gas turbines: Here the fuel specification requirements before the injection are very severe and can only be obtained by an extremely thorough precleaning of the fuel.
Figure 7-1 Marine Fuel Sulphur Limits
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Table 7-1 Requirements for marine distillate fuels
1
•
Note that although predominantly consisting of distillate fuel, the residual oil proportion can be significant. 1 mm2/s = 1 cSt
•
Purchasers should ensure that this pour point is suitable for the equipment on board, especially if the vessel operates in both the northern and southern hemispheres.
•
This fuel is suitable for use without heating at ambient temperatures down to —16°C.
•
A sulfur limit of 1.5 % (m/m) will apply in SOx emission control areas designated by the International Maritime Organization, when its relevant protocol enters into force. There may be local variations, for example the EU requires that sulphur content of certain distillate grades be limited to 0.2 % (m/m) in certain applications.
•
If the sample is clear and with no visible sediment or water, the total sediment existent and water tests shall not be required.
•
A fuel shall be free of used lubricating oils (ULOs) if one or more of the elements zinc, phosphorus and calciumare below or at the specified limits. All three elements shall exceed the same limits before a fuel shall be deemed to contain ULOs.
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Marine Diesel Fuel/Marine Gas Oil
These fuels are blends of distilled fuel combined with small amounts of HFO. They have lower levels of sulfur content than HFO and are cleaner burning. Though these fuels are more expensive, elimination of heating and extensive treatment systems help justify the higher costs. Current and future regulation will further restrict the allowable levels of Sulphur in distillate fuels, reducing pollution but almost certainly increasing costs as well.
8.1
Diesel Fuel Grades Historically, the quality of automotive fuels in the United States was specified by ASTM
standards. Diesel fuels are covered by the ASTM D975 standard. Since 2004, the D975 standard has covered seven grades of diesel. Heavier fuel oils Grade 5 and 6 (residual), which are used primarily for heating purposes, are described by ASTM D396.
Table 8-1 Diesel Fuel Grades
The Sxxx designation was first adopted in the D975-04 edition of the standard to distinguish grades by sulfur content. The S5000 grades correspond to the “regular” sulfur grades, the previous No. 1-D and No. 2-D. S500 grades correspond to the previous “Low Sulfur” grades (D975-03). S15 grades are commonly referred to as “Ultra-Low Sulfur” grades or ULSD.
An ASTM standard (D2069) once existed for marine diesel fuels, but it has been withdrawn. It was technically equivalent to ISO 8217. While some marine diesel engines use No. 2 distillate, D2069 covered four kinds of marine distillate fuels: DMX, DMA, DMB, and DMC and residual fuels (see also ISO marine fuel specifications):
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•
DMX is a special light distillate intended mainly for use in emergency engines.
•
DMA (also called marine gas oil, MGO) is a general purpose marine distillate that must be free from traces of residual fuel. DMX and DMA fuels are primarily used in Category 1 marine engines (< 5 liters per cylinder).
•
DMB (marine diesel oil, MDO) is allowed to have traces of residual fuel, which can be high in sulfur. This contamination with residual fuel usually occurs in the distribution process, when using the same supply means (e.g., pipelines, supply vessels) that are used for residual fuel. DMB is produced when fuels such as DMA are brought on board the vessel in this manner. DMB is typically used for Category 2 (530 liters per cylinder) and Category 3 (≥ 30 liters per cylinder) engines.
•
DMC is a grade that may contain residual fuel and is often a residual fuel blend. It is like No. 4-D and can be used in Category 2 and Category 3 marine diesel engines.
Residual (non-distillate) fuels are designated by the prefix RM (e.g., RMA, RMB, etc.). These fuels are also identified by their nominal viscosity (e.g., RMA10, RMG35, etc.). With the growing importance of alternative diesel fuels, standards have also been developed for biodiesel fuels and their blends.
8.2
High Speed Diesel (HSD) Diesel Oil is a complex mixture of Hydro Carbons. It is a brown colored oily liquid with
pungent smell. MPRL domestically mainly markets two grades of HSD namely BS-III & BSIV. The main difference between BS-III and BS-IV in the sulphur content, i.e. for BS-III 350 ppm and BS-IV 50 ppm.
8.2.1 Application: Diesel engines are used in cars, motorcycles, boats and locomotives. Automotive diesel fuel serves to power trains, buses, trucks, and automobiles, to run construction, petroleum drilling and other off-road equipment and to be the prime mover in a wide range of power generation & pumping applications. The diesel engine is high compression, self-ignition engine. Fuel is ignited by the heat of high compression. HSD is normally used as a fuel in medium and high-speed compression ignition engines (operating above 750 rpm) in commercial vehicles, stationary diesel engines, locomotives and pumps etc. BS-IV grade is used in certain specified markets in India which includes metros and other few cities. For all other parts in India BS-III is used. MRPL manufactures both Euro IV and
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Table 8-3 IDENTITY OF MATERIAL
Table 8-2 PHYSICAL AND CHEMICAL PROPERTIES
Table 8-4 FIRE AND EXPLOSION HAZARD’S DATA
Table 8-5 REACTIVE HAZARDS
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Table 8-6 HAZARD SPECIFICATION
9
Biodiesel
Biodiesel is a clean burning alternative fuel that is gaining traction in the marine industry. As its name suggests, biodiesel is a fuel similar to diesel, but contains no petroleum products. Biodiesel is created through a chemical process called trans esterification, which separates glycerin from fat (such as soybean oil). When done in the presence of alcohol, this process leaves behind methyl esters, more commonly called biodiesel. This type of fuel can be used in a typical compression type reciprocating engine with little or no modification. Biodiesel burns cleaner than conventional diesel distillates, in addition to being made from renewable sources - these factors make biodiesel very environmentally friendly.
10 Natural Gas
First commonly used in marine propulsion on LNG vessels, natural gas is now becoming a more popular marine fuel, primarily due to its clean burning characteristics, producing significantly less carbon dioxide than other fossil fuels for the same amount of heat generated. LNG additionally produces less NOx, SOx, and particulate matter than traditional liquid fuels.
Natural gas must be stored as a liquid under pressure, and then warmed to a gas before combustion, creating some challenges in storage and piping arrangements
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11 Nuclear
Nuclear fuel for marine propulsion, perhaps the most controversial of all propulsion fuels, is typically limited to large capital military vessels. These vessels take advantage of the essentially unlimited cruising range nuclear propulsion provides, without being unduly burdened by the size and weight associated with the nuclear reactor. The high-power density and high endurance capability of a nuclear propulsion system also makes it an attractive choice for icebreaking operations. However, there are certain drawbacks to nuclear propulsion that generally limit its use to military vessels.
These constraints include the necessity for specialized (and expensive) manning, high initial cost, the complexities of handling and disposing of nuclear materials, and extremely stringent worldwide regulation.
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CHAPTER (3) SERVICE LIFE PREDICTION OF DIESEL ENGINE
12 Introduction
The research on the life of diesel engine is to predict the residual (reserve) life of militaryuse vehicle engine and to predict the timing of failure. Perfect and reasonable diesel engine life prediction research can be convenient for users to timely repair and replacement parts, which can avoid the user of the human and material resources of the waste. The life prediction method of diesel engine, the current international mainly include: Dynamic prediction, statistical prediction and empirical prediction of three methods, each has its own advantages and disadvantages, especially the experience prediction method, a large number of manual operation is not adapted to the information transmission1. Through the study on the relationship of cylinder wear, cylinder leakage and diesel engine life, which leads to the relationship between cylinder pressure and diesel engine life, according to the gas Clapeyron equation established cylinder pressure and diesel engine life mathematical model and consider the fuel injection pressure, the oil pressure and all conditions of use to modify the theoretical model, for the prediction of the service life of diesel engine proposed a more practical method.
Some studies put forward a demand forecast model of aircraft engine by analyzing the demand caused by the engine to life and random faults, through both ways of fault rate and frequency and unreliability to compute the demand caused by engine to life by engine’s specified life, remaining life, single flight task and so on and the demand caused by random faults2, other studies consider engine control aims to provide desired performance based on stability margins while Life Extending Control (LEC) means to change the original control schedule to maintain the performance of engine and extend engine life3, but this study mainly does research on service life prediction of diesel engine from the three aspects of air cylinder pressure, fuel injection pressure and oil pressure, which is different from demand forecast model of vehicle engine based on the demand of random failure of the previous literatures and the data needed to be collected by the established model is more practical and accurate.
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13 MATERIALS AND METHODS
Main factors affecting the life of diesel engine: In addition to the cylinder pressure, fuel injection pressure, oil pressure, external conditions of use and other factors are closely related to the life of diesel engine. 13.1.Influence of cylinder pressure on the life of diesel engine: At present, the wear condition of diesel engine cylinder liner is both home and abroad to evaluate the diesel engine life. Uneven wear of diesel engine cylinder liner will lead to the gap between the piston ring and the cylinder wall becomes larger and over time will make a large amount of air leakage in the cylinder body, so the wear of the cylinder liner is the main factor leading to the end of diesel engine life. However, the direct consequence of the leakage in the cylinder body is the reduction of the pressure in the cylinder, so the cylinder pressure can directly reflect the wear of the cylinder liner, as the main parameters of the diesel engine life prediction. At the same time, it is unnecessary to remove the diesel engine cylinder head for measuring the state parameters of cylinder pressure, only need to remove the injector is directly connected with the corresponding sensor can measure. 13.2.Effects of fuel injection pressure and oil pressure on the life of diesel engine: In addition to the cylinder pressure as the main factors of diesel engine life prediction, the researchers will consider the impact of fuel injection pressure and oil pressure on diesel engine life, fuel injection pressure is reduced, fuel injection atomization quality becomes poor, the fuel cannot be good with the air mixture, diesel engine performance is reduced, long time work will affect the diesel engine life, in contrast to the high injection pressure is not normal injection, long time working diesel engine life will be reduced. Therefore, the height of the injection pressure will become an important reason for the diesel engine service life, the value of the oil pressure should be high enough to ensure the reliable transmission of oil to the lubrication surface. If the engine oil pressure is too low, will not be able to carry a large amount of lubricating oil supply to the friction between, causing the piston ring and cylinder wall and crankshaft bearing wear serious, greatly reducing the dynamic performance of the diesel engine, work for a long time will reduce the service life of the diesel engine. Therefore, fuel injection pressure and oil pressure are the auxiliary parameters influencing the life prediction of diesel engine.
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13.3.Influence of the external environment on the life of diesel engine: In addition to the above three state parameters, the researchers will consider the influence of various environmental factors and various conditions on the life of diesel engine. Than as models of diesel engine is used in different conditions, even strictly follow the diesel engine specification requirements, parts of the wear and tear strength may also vary several times, the impact wear and tear parts outside factors can be divided into three categories: The first is the factors unrelated to vehicle users: The road, climatic conditions and types of goods, quantity, distance etc., the second is a part of relationship with the factors of vehicle users: The use of quality system and operation material etc., the third category is depends entirely on a vehicle user factors, such as driving driver technology level, maintenance repair level and so on. These state parameters will vary greatly with different environmental areas, so it is difficult to measure, so the other environmental factors and conditions of use will be used as the correction state parameters.
14 Diesel engine life prediction model
14.1. Relationship between cylinder air leakage and diesel engine life: Due to the cylinder leakage and diesel engine running time is closely related. The cylinder leakage rule is increased with the increase of the diesel engine working time. This fact has a very close relationship with the cylinder wear and diesel engine life. 14.1.1. Basic rated wear life: The basic rating wear life of the cylinder liner is defined as the amount of gas leakage of the cylinder to the diesel engine intake Qe (%) (the general provisions of 20%), diesel engine work time (h) or the distance of the vehicle (km). 14.1.2. Basic rating of the air leakage of the cylinder: In order to predict the service life of diesel engine, the maximum value of air leakage is often required to be the standard of the diesel engine life. The researchers take the diesel engine life as the basis of the end of the cylinder air leakage, known as "The basic rating of the amount of air leakage".
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The service life of diesel engine corresponding to the basic rated air leakage is Lb (km), the Lb is called the basic rating life of diesel engine, the value of which is determined by the manufacturing industry and the use of the Department to develop. The relationship between the cylinder leakage of diesel engine Q and the service life of diesel engine L.
14.2.Relationship between the air leakage of the cylinder and the service life of diesel engine: From the life curve shown in Fig. 1, it can be seen that there is a relationship between the service life of diesel engine L and the cylinder wear leakage Q: (1)
Figure 14-1 Life curve of diesel engine
Where: Q
=
The cylinder leakage (%)
β
=
The life index related to the compression ratio of the diesel engine
β
=
The ε for the compression ratio of the diesel engine and the n for the life
= ε/n
index reduction factor, the value of which is determined by the experiment L
=
The remaining life of diesel engine (1×104 km)
In our country, the cylinder leakage Qb of the end of the service life of diesel engine and corresponding to the life of Lb (1×104 km). Then:
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(2) By the Eq. 2, the Eq. 3 for life can get:
(3)
Therefore, when the Qi is measured, the remaining life Li of the diesel engine can be predicted based on the Eq. 3.
14.3.Relationship between cylinder pressure and the life of diesel engine: Obviously, the application of the Eq. 3 to predict life is not easy, because in the practical application, the cylinder leakage is very unpredictable and cylinder pressure is easily measured, so the application of on-line measurement of cylinder pressure to predict diesel engine life is relatively easy to achieve. As the cylinder pressure can more directly reflect the wear of the cylinder liner, so it can be said that the cylinder pressure as the diesel engine life prediction of the state parameters, reflected by the cylinder liner wear, the application of cylinder pressure to predict the life of diesel engine is customary at home and abroad. From the above analysis, it can be known that the cylinder wear leads to the leakage of the cylinder and the direct reflection of the leakage of the cylinder is the reduction of the cylinder pressure. So, if it can be found that the function relationship between the cylinder gas leakage and cylinder pressure and then according to the relationship between the cylinder leakage and diesel engine life, the researchers can deduce the function relationship between the cylinder pressure and the diesel engine life.
14.4.Relationship between the cylinder pressure P and the cylinder air leakage Q in equal volume and isothermal condition: According to the ideal gas state equation, that is the Clapeyron equation: (4)
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So: (5) Where: P
=
Cylinder pressure
V
=
The volume of a gas in an instant cylinder
Q
=
Gas quality
R
=
Universal gas constant
T
=
Gas temperature
Μ
=
Mol g mol–1 gas Moore
As the cylinder before and after the gas leak after the volume of V constant (piston in spite of the movement but because it is the same time of comparison, it can be considered that the volume of gas has not changed, that is, in the state of equal volume). The gas quality before the cylinder is Qe, the cylinder pressure is Pe, the air leakage quality is Qi, the gas quality becomes Qe-Qi after the leak is changed, the cylinder pressure at this time is Pi. Then there:
Due to the volume V is equal before and after the leak, so it is:
So:
So:
So:
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Then it is: (6) 14.4.1. Equation for the service life of a diesel engine by cylinder pressure: Taking the results above into the equation:
Then the life equation r the diesel engine is:
(7)
where, Qe is a suction stroke piston at the lower end and the air quality of the air when the cylinder is not leaking. Obviously for the cylinder diameter of d, stroke of l, combustion chamber volume of Vc, the air density of μ for the diesel engine, the air quality is: (8) For a certain type of diesel engine this value is a fixed value. 14.4.2. Rated air leakage and rated pressure: The Pe is the end of the compression cylinder pressure, cylinder pressure for gas cylinder when the mass is Qe, generally considered: •
When the piston is located at the lower end of the cylinder pressure is a atmospheric pressure
•
When the piston is located at the top end of the cylinder pressure application experience equation Pe = 0.15ε-0.22 (Mpa) to calculate
In our country, the end of the diesel engine compression stroke, the air quality of the cylinder should not be less than 80% of the intake, that is, the amount of gas leakage should not be higher than 20%. The researchers set Qb = 0.8 Qe.
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So, the prediction equation of the life of diesel engine becomes:
(9)
So as long as the cylinder pressure Pi can be measured can predict the life of diesel engine Li. For a certain type of diesel engine, the compression ratio is a fixed value. Therefore, the compression ratio can be used to express the life equation:
(10)
Where: Lb
=
The basic rating life of diesel engine
Pi
=
Online actual measurement of cylinder pressure
ε
=
Compression ratio (the compression ratio of diesel engine is generally 17∼23)
This Eq. 10 is for predicting the service life of diesel engine, which is expressed by cylinder pressure. The Eq. 10 shows that, as long as the measured cylinder pressure Pi can predict the remaining life of diesel engine Li. Equation 10 is usually referred to as the equation for predicting the remaining life of diesel engine with cylinder pressure.
14.5.Functional relationship between fuel injection pressure, engine oil pressure and service life of diesel engine: Diesel engine life prediction Eq. 10 is only the main state parameters of diesel engine life prediction and it is a theoretical prediction equation. The analysis of the second section shows that the fuel injection pressure and engine oil pressure are the two main parameters of diesel engine life prediction. The work of the injection system is to rely on the fuel injection pressure curve for real-time monitoring but has not yet seen such a set of measurement system, it is necessary to develop the system, in order to clarify the relationship between the technical state of the injection system and diesel engine life. The exact relationship between injection pressure and the life of diesel engine is not known but it is clear that, with the extension of working time of diesel engine, each friction pair will have a certain wear and the wear of injection pump plunger will gradually reduce the 64
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injection pressure. The injection pressure decreased, resulting in a decline in the quality of fuel atomization, coke formation, acceleration of cylinder liner wear, reduce the service life of the diesel engine. It can be concluded that in the allowable range of injection pressure, fuel injection pressure and the life of diesel engine are as follows: (11) Where: Lp
=
The service life of considering the reduction of the fuel injection pressure
Lj
=
The life of diesel engine calculated by Eq. 10
Pp
=
Actual measurement of fuel injection pressure
Pbp
=
Standard injection pressure
M
=
The life reduction index, which is generally related to the structure and wear degree of the injector
kp
=
Correction factor
Figure 14-2 Relationship between fuel injection pressure and the life of diesel engine
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In the same way, the oil pressure of the main oil channel should be high enough to ensure the reliable transmission of the oil to the surface of the lubricating oil. If the engine oil pressure is too low, will not be able to carry a large amount of lubricating oil supply to the friction between, which causes include piston ring and the inner wall of the cylinder, crankshaft bearing shells of serious wear, greatly reducing the dynamic performance of the diesel engine, work for a long time will be reduced and the service life of the diesel engine. In the normal operation of the diesel engine, can be drawn in the normal range of oil pressure, oil pressure and the life of diesel engine expectancy is roughly the following relationship:
(12)
Where: Lj
=
Service life of diesel engine after changing the engine oil pressure
Li
=
Diesel engine life calculated by Eq. 10
Pj
=
The actual measurement of oil pressure
Pbj
=
Standard oil pressure
n
=
Life change index, which is generally related to the structure of the oil pump and the wear degree of the friction pair
kj
=
Correction
Correction coefficient of
the mathematical
model through
the
comprehensive
correction
coefficient: The conditions and operating conditions of diesel engine are varied, such as different roads, temperature, humidity and windblown sand and the quality and technical level, fuel oil, lubricating oil quality and load speed, etc., all of which will have a certain impact on diesel engine life. The method considered is to introduce the comprehensive correction coefficient to correct the theoretical mathematical model. The comprehensive correction factor is the sum of the actual conditions of use and the post correction factor of the environmental factors.
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Considering all the above parameters, the comprehensive correction coefficient K is:
where, K is the comprehensive correction coefficient. However, due to the limited time, the precise value of the correction factor and the specific functional relationship between them need to be further studied. Considering the fuel injection pressure, oil pressure and the influence of using and environmental factors, the researcher get the equation of the life prediction of diesel engine:
(13)
Figure 14-3 Relationship between oil pressure and the life of diesel engine
Figure 14-4 Types of modified state parameters for the life prediction of diesel engine
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Or:
(14)
The K is the comprehensive correction coefficient:
where, the unit of the life of diesel engine Li changes with the basic rating life of units Lb.
15 RESULTS
1) Experimental verification: With a vertical 195 diesel engine for bench test, the compression ratio of the diesel engine is 17 and the crankshaft speed is controlled by the motor and the gear box. The test bench is carried out by means of a cold drag and the diesel engine consists of a three-phase AC motor through the transmission belt is connected with the gear box and the diesel engine crankshaft is driven by the transmission on the transmission shaft. Three successive measurements are calculated.
Error analysis Calculation of the average error of the cylinder pressure:
That is: 0.2%.
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Average error calculation of the remaining life of diesel engine: Life equation:
Into the equation: •
L1 = 12.33×104 km
•
L2 = 9.69×104 km
•
L1 = 10.52×104 km
Average error:
That is: 9.1%.
2) Analysis of measurement results: From the measurement results of Table 2, the average error of cylinder pressure is about 0.4%, which is the key parameter of diesel engine life prediction, which directly affects the accuracy of the prediction of diesel engine life and the other two pressure errors can also meet the requirements of the measurement. The repeatability error of fuel injection pressure looks slightly higher which reached 1.3%. This is because of the large measurement range of injection pressure sensor; the resolution is relatively low. he minimum error of oil pressure is only 0.1%, which is necessary, because the oil pressure is generally only 0.2~0.4 MPa, if the resolution of the sensor is low, it will appear the phenomenon of miscarriage of justice, so it can be seen that the choice of sensors is very important.
Table 15-1 Experimental results of the diesel engine bench test
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Measured data can be calculated: Diesel engine life prediction of the average repeatability error is about 9%, the average life of 100,000 km of diesel engine, its prediction error is about 0.99 m, about 10,000 km.
16 DISCUSSION
Traditional life prediction of diesel engine is often used in the static analysis of oil analysis or radioactive isotopes. Through the static test of the content of iron in lubricating oil of diesel engine, to judge the wear of diesel engine cylinder and then predict the life of diesel engine. The static analysis methods need a certain amount of time for instrument control and data analysis and the current information on the working state of engine cannot be provided in a timely manner. Practice has proved that the traditional method to determine the life of diesel engine is very discrete, relatively low accuracy, about 80% earlier. At present, Whenua et al. proposed statistical distribution model for evaluating lifetime of automotive engine, through identifying the distribution function of the cylinder wear lifetime of automotive engine, a lifetime evaluation model for engines based on cylinder wear rate was set up. By analyzing the wear rate of air cylinder with time series method, this paper gained a relatively precision predicting result of the life of automotive engine with BP neural network by Chunhui and Lei. Qipao et al. proposed the method of predicting life time of cylinder based on measuring the air pressure in engine cylinder. The above methods are mainly based on the cylinder wear rate, considering the single factor and need to be built based on a large number of statistical data, the life prediction of engine is not accurate enough. This study considering the impact of the diesel engine life for a variety of factors on the basis of previous studies, through the on-line dynamic measurement, real-time assessment, the life prediction of diesel engine is more accurate, and it can provide timely the reliable basis for vehicle maintenance and repair.
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17 Example
17.1 Sulzer RTA and RT-flex Engines
Figure 17-1 Inspection or Overhaul Intervals and Lifetimes 1) Intervals for inspection or overhaul and approximate lifetimes are estimates only given based on past experience for engines fully according to presently applicable Wärtsilä Switzerland Ltd specifications. For prudent planning of maintenance, running hours might be chosen at the beginning as per ‘initial’ schedule until own experience is available. They are given for information purposes only and do not constitute any guarantee or warranty whatsoever, as the results can vary considerably due to numerous conditions and influences such as but not limited to:
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•
Environmental and operating conditions
•
Heavy fuel and lubricating oil qualities within the specifications of Wärtsilä;
•
Engine load factor within to Wärtsilä specifications;
•
Fuel, lubricating oil and cooling water care according to the specifications of Wärtsilä;
•
Overhaul according to engine manuals;
•
Only genuine spare parts used;
•
Careful and continuous engine monitoring.
2) Total time for withdrawing and refitting (mid-size bore) assuming good conditions with ready tools, devices and lifting arrangements. Time for cleaning and overhaul should be added. 3) Checks at random – all within 4 or 5 years depending on respective classification or other applicable rules. 4) Reconditioning. 5) Rechroming of valve shaft possibly earlier. 6) Welding, rechroming of piston ring grooves.
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CHAPTER (4) ENVIRONMENTAL POLLUTION BY DIESEL ENGINE
18 Interdiction
Diesel engines have high efficiency, durability, and reliability together with their lowoperating cost. These important features make them the most preferred engines especially for heavy-duty vehicles. The interest in diesel engines has risen substantially day by day. In addition to the widespread use of these engines with many advantages, they play an important role in environmental pollution problems worldwide. Diesel engines are considered as one of the largest contributors to environmental pollution caused by exhaust emissions, and they are responsible for several health problems as well. Many policies have been imposed worldwide in recent years to reduce negative effects of diesel engine emissions on human health and environment. Many researches have been carried out on both diesel exhaust pollutant emissions and aftertreatment emission control technologies. In this paper, the emissions from diesel engines and their control systems are reviewed. The four main pollutant emissions from diesel engines (carbon monoxide-CO, hydrocarbons-HC, particulate matter-PM and nitrogen oxidesNOx) and control systems for these emissions (diesel oxidation catalyst, diesel particulate filter and selective catalytic reduction) are discussed. Each type of emissions and control systems is comprehensively examined. At the same time, the legal restrictions on exhaust-gas emissions around the world and the effects of exhaust-gas emissions on human health and environment are explained in this study.
19 The emissions from diesel engines
The diesel engine is an auto-ignition engine in which fuel and air are mixed inside the engine. The air required for combustion is highly compressed inside the combustion chamber. This generates high temperatures which are sufficient for the diesel fuel to ignite spontaneously when it is injected into the cylinder. Thus, the diesel engine uses heat to release the chemical energy contained in the diesel fuel and to convert it into mechanical force (Bosch 2005). Carbon
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and hydrogen construct the origin of diesel fuel like most fossil fuels. For ideal thermodynamic equilibrium, the complete combustion of diesel fuel would only generate CO2 and H2O in combustion chambers of engine (Prasad and Bella 2010). However, many reasons (the air–fuel ratio, ignition timing, turbulence in the combustion chamber, combustion form, air–fuel concentration, combustion temperature, etc.) make this out of question, and a number of harmful products are generated during combustion. The most significant harmful products are CO, HC, NOx, and PM.
Figure 19-1 The compositions of diesel exhaust gas The figure shows the approximate composition of diesel exhaust gas (Khair and Majewski 2006). Pollutant emissions have a rate of less than 1 % in the diesel exhaust gas. NOx has the highest proportion of diesel pollutant emissions with a rate of more than 50 %. After NOx emissions, PM has the second highest proportion in pollutant emissions. Because diesel engines are lean combustion engines, and the concentration of CO and HC is minimal. Besides, pollutant emissions include a modicum of SO2 depending the specifications and quality of fuel. It is produced by the sulfates contained in diesel fuel. For the present, there is not any aftertreatment system like a catalytic converter to eliminate SO2.
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Nowadays, most of oil distributors and customers prefer ultra-low sulfur diesel (ULSD) for diesel engines to prevent harmful effect of SO2. In this section, the four main pollutant emissions (CO, HC, PM, and NOx) from diesel engine are explained. Each type of emission is investigated individually and the impacts of each emission on environmental and health problems are also revealed.
19.1 Carbon monoxide (CO) Carbon monoxide results from the incomplete combustion where the oxidation process does not occur completely. This concentration is largely dependent on air/fuel mixture and it is highest where the excess-air factor (k) is less than 1.0 that is classified as rich mixture (Wu et al. 2004). It can be caused especially at the time of starting and instantaneous acceleration of engine where the rich mixtures are required. In the rich mixtures, due to air deficiency and reactant concentration, all the carbon cannot convert to CO2 and be formed CO concentration. Although CO is produced during operation in rich mixtures, a small portion of CO is also emitted under lean conditions because of chemical kinetic effects (Faiz et al. 1996). Diesel engines are lean combustion engines which have a consistently high air–fuel ratio (k[1). So, the formation of CO is minimal in diesel engines. Nevertheless, CO is produced if the droplets in a diesel engine are too large or if insufficient turbulence or swirl is created in the combustion chamber (Demers and Walters 1999). Carbon monoxide is an odorless and colorless gas. In humans, CO in the air is inhaled by the lungs and transmitted into the bloodstream. It binds to hemoglobin and inhibits its capacity to transfer oxygen. Depending on CO concentration in the air, as thus leading to asphyxiation, this can affect the function of different organs, resulting in impaired concentration, slow reflexes, and confusion (Raub 1999; Kampa and Castanas 2008; Walsh 2011; Strauss et al. 2004).
19.2 Hydrocarbons (HC) Hydrocarbon emissions are composed of unburned fuels as a result of insufficient temperature which occurs near the cylinder wall. At this point, the air–fuel mixture temperature is significantly less than the center of the cylinder (Demers and Walters 1999; Correa and Arbilla 2008). Hydrocarbons consist of thousands of species, such as alkanes, alkenes, and aromatics. They are normally stated in terms of equivalent CH4 content (Hiroyuki et al. 2011). Diesel
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engines normally emit low levels of hydrocarbons. Diesel hydrocarbon emissions occur principally at light loads. The major source of light-load hydrocarbon emissions is lean air–fuel mixing. In lean mixtures, flame speeds may be too low for combustion to be completed during the power stroke, or combustion may not occur, and these conditions cause high hydrocarbon emissions (Zheng et al. 2008). In Diesel engines, the fuel type, engine adjustment, and design affect the content of hydrocarbons. Besides, HC emissions in the exhaust gas depend on irregular operating conditions. High levels of instantaneous change in engine speed, untidy injection, excessive nozzle cavity volumes, and injector needle bounce can cause significant quantities of unburned fuel to pass into the exhaust (Payri et al. 2009). Unburned hydrocarbons continue to react in the exhaust if the temperature is above 600 _C and oxygen present, so hydrocarbon emissions from the tailpipe may be significantly lower than the hydrocarbons leaving the cylinder (Faiz et al. 1996). Hydrocarbon emissions occur not only in the vehicle exhaust, but also in the engine crankcase, the fuel system, and from atmospheric venting of vapors during fuel distribution and dispensing (Faiz et al. 1996). Crankcase hydrocarbon emissions and evaporative losses of hydrocarbon emissions have, respectively, 20–35 and 15–25 % while tailpipe hydrocarbon emissions have 50–60 % of total hydrocarbon emissions (Dhariwal 1997). Hydrocarbons have harmful effects on environment and human health. With other pollutant emissions, they play a significant role in the formation of ground-level ozone. Vehicles are responsible for about 50 %of the emissions that form ozone. Hydrocarbons are toxic with the potential to respiratory tract irritation and cause cancer (Diaz-Sanchez 1997; Krzyzanowski et al. 2005).
19.3 Particulate matter (PM) Particulate matter emissions in the exhaust gas are resulted from combustion process. They may be originated from the agglomeration of very small particles of partly burned fuel, partly burned lube oil, ash content of fuel oil, and cylinder lube oil or sulfates and water (Demers and Walters 1999; Maricq 2007). Most particulate matters are resulted from incomplete combustion of the hydrocarbons in the fuel and lube oil. In an experimental study, typical particle composition of a heavy-duty diesel engine is classified as 41 % carbon, 7 % unburned fuel, 25 % unburned oil, 14 % sulfate and water, 13 % ash and other components (Kittelson 1998). In another study, It is reported that PM consists of elemental carbon (%31 %), sulfates
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and moisture (%14 %), unburnt fuel (%7 %), unburnt lubricating oil (%40 %) and remaining may be metals and others substances (Agarwal 2007). Diesel particulate matters are typically spheres about 15–40 nm in diameter, and approximately more than 90 % of PM is smaller than 1 lm in diameter. The formation process of PM emissions is dependant on many factors as the combustion and expansion process, fuel quality (sulfur and ash content), lubrication oil quality, and consumption, combustion temperature, exhaust gas cooling (Burtscher 2005). Particulate matter emissions from diesel engines are considerably higher (six to ten times) than from gasoline engines. Diesel particle emissions can be divided into three main components: soot, soluble organic fraction (SOF), and inorganic fraction (IF). More than 50 % of the total PM emissions are soot that is seen as black smoke. SOF consists of heavy hydrocarbons adsorbed or condensed on the soot. It is derived partly from the lubricating oil, partly from unburned fuel, and partly from compounds formed during combustion. SOF values are too high at light engine loads when exhaust temperatures are low (Sarvi et al. 2011; Tighe et al. 2012; Metts et al. 2005; Stanmore et al. 2001; Sharma et al. 2005). Many researches are performed to detect the impact of PM emissions on environment and human health. In these researches, It is documented that inhaling of these particles may cause to important health problems such as premature death, asthma, lung cancer, and other cardiovascular issues. These emissions contribute to pollution of air, water, and soil; soiling of buildings; reductions in visibility; impact agriculture productivity; global climate change (Englert 2004; OECD 2002; Michael and Kleinman 2000).
19.4 Nitrogen oxides (NOx) Diesel engines use highly compressed hot air to ignite the fuel. Air, mainly composed of oxygen and nitrogen, is initially drawn into the combustion chamber. Then, it is compressed, and the fuel is injected directly into this compressed air at about the top of the compression stroke in the combustion chamber. The fuel is burned, and the heat is released. Normally in this process, the nitrogen in the air does not react with oxygen in the combustion chamber and it is emitted identically out of the engine. However, high temperatures above 1,600 _C in the cylinders cause the nitrogen to react with oxygen and generate NOx emissions. So, it will not be wrong to say that the major influences of the formation of NOx are the temperature and concentration of oxygen in the combustion. The amount of produced NOx is a function of the maximum temperature in the cylinder, oxygen concentrations, and residence time. Most of the emitted NOx is formed early in the combustion process, when the piston is still near the top of 77
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its stroke. This is when the flame temperature is the highest. Increasing the temperature of combustion increases the amount of NOx by as much as threefold for every 100 _C increase (Lee et al. 2013; Bosch 2005). Nitrogen oxides are referred as nitrogen oxide (NO) and nitrogen dioxide (NO2). NO constitutes 85–95 % of NOx. It is gradually converted to NO2 in atmospheric air. While NO and NO2 are lumped together as NOx, there are some distinctive differences between these two pollutants. NO is a colorless and odorless gas, while NO2 is a reddish-brown gas with pungent odor (Chong et al. 2010; Hoekman and Robbins 2012). Road transport is the most important cause of urban NOx emissions worldwide contributing to 40–70 % of the NOx. Among various types of vehicles, diesel vehicles are the most important contributors to NOx emissions. Compared with gasoline engines, they need higher temperatures because they are compressionignition engines. Diesel engines are responsible for about 85 % of all the NOx emissions from mobile sources, primarily in the form of NO (Lee et al. 2013; Wang et al. 2012). Nitrogen oxides emissions from vehicles are responsible for a large amount of environmental and health hazard. NOx emissions contribute to acidification, formation of ozone, nutrient enrichment, and smog formation, which have become considerable problems in most major cities worldwide (Grewe et al. 2012). In the atmosphere, NOx emissions react chemically with other pollutants to form tropospheric ozone (the primary component of photochemical smog) and other toxic pollutants. NO and NO2 are considered as toxic; but NO2 has a level of toxicity five times greater than that of NO and it is also a direct concern of human lung disease. Nitrogen dioxide can irritate the lungs and lower resistance to respiratory infection (such as influenza). NOx emissions are important precursors to acid rain that may affect both terrestrial and aquatic ecosystems. Nitrogen dioxide and airborne nitrate also contribute to pollutant haze, which impairs visibility (Kagawa 2002; Hoeft et al. 2012).
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Table 19-1 Euro standards of E.U for heavy-duty vehicles at 2012
20 Emission control systems for diesel engine vehicles
In today’s world, environmental protection has advanced to become a topic of central concern. Many agencies and organizations are tried to prevent the damage on environment and human health caused by greenhouse gases and pollutant emissions. Due to the adverse effects of diesel emissions on health and environment, governments put forward to the requirements for permissible exhaust emission standards. Europe has developed Euro standards which have continuously been lowered since 1993 with the Euro I to Euro VI, respectively. Table 1 shows Euro standards for M1 and M2, N1 and N2 vehicles as defined in Directive 70/156/EC with reference mass B2,610 kg. The limits are defined in mass per energy (g/kWh) in this table. Regulations in Euro standards become progressively more stringent in the ensuing years. Compared to Euro I standard, Euro VI standard for CO, HC, NOx, and PM emissions was decreased, respectively, 66, 76, 95, and 98 %. The implementation date of Euro VI standard for heavy-duty vehicles was 1st of September 2014 (Delphi et al. 2012). The emission values which have been more stringent day by day obliged the vehicle manufacturers to work on reducing pollutant emission from vehicles. In the studies that have been carried out for decades, engine modifications, electronic controlled fuel injections systems, and improvement fuel properties have been focused on. However, these measures have failed to achieve emission reduction determined by standards. The desired emission levels can be achieved only by means of aftertreatment emission control systems. Vehicles are equipped
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with emission control systems to meet the actual emissions standards and requirements. With emission control systems, pollutants from the exhaust can be eliminated after it leaves the engine, just before it is emitted into the air (Prasad and Bella 2010; Bosch 2005). Among the emission control systems of diesel engines, most researches and studies have been carried out on reduction of NOx emissions because NOx content in exhaust of diesel engine has the highest percentage among the pollutant emissions. Of the researches so far, exhaust gas recirculation (EGR), lean NOx trap (LNT), and SCR are the most focused technologies to substantially eliminate the NOx emissions. In EGR systems, to reduce NOx emissions, exhaust gas is recirculated back into the combustion chamber and mixed with fresh air at intake stroke. Consequently, the efficiency of combustion is worsened leading to the decrease of combustion temperature which means a reducing in NOx formations. EGR has a widely used range in diesel vehicles. However; it cannot achieve singly high NOx conversion efficiency and reduction which meets current emission standards for especially heavy-duty vehicles. Also, due to the reduction of temperature in cylinder, this technology generates an increase of HC and CO emissions. (Bauner et al. 2009). LNT technology, also called NOx-storage-reduction (NSR) or NOx adsorber catalyst (NAC), has been developed to reduce NOx emission especially under lean conditions. During lean engine conditions, LNT stores NOx on the catalyst wash coat. Then, under the fuel-rich engine conditions it releases and reacts the NOx by the usual three-way type reactions. LNT catalyst mainly consists of three key components. These components are an oxidation catalyst (Pt), a NOx storage ambiance (barium (Ba) and/or other oxides), and a reduction catalyst (Rh). In LNT technology, Platinum-based catalysts are the most used catalysts because of their NOx reduction at low temperature and stability in water and sulfur. Like EGR technology, LNT technologies are insufficient to provide desired NOx emissions reduction. Apart from EGR and LNT technologies, it is possible to meet the current emissions standards with SCR technology. So, SCR technology is a respectable recent technology that many researchers are interested in. In this section, emission control systems for diesel engines are explained particularly. Because of their extensive usage; DOC, DPF, and SCR systems especially for heavy-duty diesel engines are considered separately.
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20.1 Diesel oxidation catalyst (DOC) The main function of DOCs is to oxidize HC and CO
emissions.
DOCs
play
a
Besides, role
in
decreasing the mass of diesel particulate oxidizing
emissions some
hydrocarbons
of that
by the are
Figure 20-1 Diesel oxidation catalyst
adsorbed onto the carbon particles (Chen and Schirmer 2003; Wang et al. 2008). DOCs may also be used in conjunction with SCR catalysts to oxidize NO into NO2 and increase the NO2: NOx ratio. There are three main reactions which occur in DOCs (Zheng and Banerjee 2009).
CO and HC are oxidized to form CO2 and H2O [Eqs. (1), (2)] in the DOC (Fig. 2). Diesel exhaust gases generally contain O2, ranging from 2 to 17 % by volume, which does not react with the fuel in the combustion chamber. This O2 is steadily consumed in DOC (Yu and Kim 2013). Another chemical reaction that occurs in DOCs is the oxidizing of NO to form NO2 as seen in Eq. (3). NO2 concentration in the NOx is vital for downstream components like DPF and SCR. A high NO2 concentration in the NOx generates to increase efficiency of DPF and SCR. In the untreated engine exhaust gas, the NO2 component in the NOx is only about 10 % at most operating points. With the function of the DOC, NO2:NO rate is increased by inducing thermodynamic equilibrium (Lee et al. 2008; Sampara et al. 2007). Temperature is an effective function on DOC efficiency. The effectiveness of the DOC in oxidizing CO and HC can be observed at temperatures above ‘‘light-off’’ for the catalytic activity. Light-off temperature is defined as the temperature where the reaction starts in catalyst and varies depending on exhaust composition, flow velocity, and catalyst composition.
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DOC can also be used as a catalytic heater. The oxidation of CO and HC emissions generates to release heat. This heat is used to raise the exhaust-gas temperature downstream of DOC. The rising in the exhaust temperature supports DPF regeneration. In DOC, the temperature of the exhaust gas rises approximately above 90 _C for every 1 % volume of CO oxidation. Since the temperature rise is very rapid, a steep temperature gradient becomes set in DOC. The resulting stress in the ceramic carrier and catalytic converter is limited to the permitted temperature hike of about 200–250 _C (Bosch 2005). DOC is commonly a monolith honeycomb structure made of ceramic or metal. Besides this carrier structure, it consists of an oxide mixture (washcoat) composed of aluminum oxide (Al2O3), cerium oxide (CeO2), zirconium oxide (ZrO2), and active catalytic noble metals such as platinum (Pt), palladium (Pd), and rhodium (Rh). The primary function of the washcoat is to provide a large surface area for the noble metal, and to slow down catalyst sintering that occurs at high temperatures, leading to an irreversible drop in catalyst activity. The quantity of noble metals used for the coating, which often referred to as the loading, is specified in g/ft3. The loading is approximately 50–90 g/ft3. Currently, DOC containing Pt and Pd is most commonly used for oxidation and many studies conducted by researchers focused on these precious metalbased catalysts (Kolli et al. 2010; Kim et al. 2003; Wiebenga et al. 2012; Wang et al. 2008; Haneda et al. 2011). The major properties in choice of DOCs are light-off temperature, conversion efficiency, temperature stability, and tolerance to poisoning and manufacturing costs. However, parameters as channel density (specified in cpsi (channels per square inch)), wall thickness of the individual channels, and the external dimensions of converter (crosssectional area and length) have a significant role on properties of DOCs. Channel density and wall thickness determine heat up response, exhaust-gas backpressure, and mechanical stability of the catalytic converter (Zervas 2008). The volume of DOC (Vc) is defined as a factor of exhaust-gas volumetric flow, which is itself proportional to the swept volume (Vs) of the engine. Typical design figures for a DOC are Vc/Vs = 0.6–0.8. The ratio of exhaust-gas volumetric flow [Vf (m3/h)] to catalyst volume [Vc (m3)] is termed space velocity [SV (h-1)]. Typical figures of SV for an oxidation catalyst are 150,000–250,000 h-1 (Bosch 2005).
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Figure 20-2 Filtration of DPF
Since first introduction in 1970s, DOCs remain a key technology for diesel engines until nowadays (Wang et al. 2008). All new diesel engines mounted in passenger cars, light-duty and heavy-duty diesel vehicles are now equipped with DOCs. Reductions in emission from DOC use are estimated to be around 60–90 % for HCs and CO. DOCs are extensively preferred emission control systems not only for heavy-duty vehicles but also light-duty vehicles, in many countries such as Europe, USA, and Japan. The oxidation catalysts containing Pt and Pd are the most popular catalysts in world market. One of the major problems of these precious catalysts is that they carry reaction of SO2 to SO3 which consequently react with water and generates forms of sulfates and sulfuric acid. These forms have quite harmful effects like damaging the aftertreatment emission control systems as well as causing several environmental and health problems. There is no technology to prevent and eliminate these forms. Although ULSD is used in many countries worldwide,
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the problem could not be solved completely. Using alternative fuels as biodiesel, methyl alcohol etc., can completely reduce or eliminate this pollutant. Besides, it is possible to increase the conversion efficiency of DOC using of alternative fuels (Zhu et al. 2013).
20.2 Diesel particulate filter (DPF) DPFs have been applied in the production of vehicles since 2000. They are used to remove PM emissions from the exhaust gas by physical filtration and usually made of either cordierite (2MgO–2Al2O3–5SiO2) or silicon carbide (SiC) honeycomb structure monolith with the channels blocked at alternate ends. The plugged channels at each end force the diesel particulates matters through the porous substrate walls, which act as a mechanical filter (Fig. 3). As soot particles pass through the walls, they are transported into the pore walls by diffusion where they adhere. This filter has a large of parallel mostly square channels. The thickness of the channel walls is typically 300–400 lm. Channel size is specified by their cell density (Typical value: 100–300 cpsi) (Kuki et al. 2004; Ohno et al. 2002; Tsuneyoshi and Yamamoto 2012). The filter walls are designed to have an optimum porosity, enabling the exhaust gases to pass through their walls without much hindrance, whilst being sufficiently impervious to collect the particulate species. As the filter becomes increasingly saturated with soot, a layer of soot is formed on the surface of the channel walls. This provides highly efficient surface filtration for the following operating phase. However, excessive saturation must be prevented. As the filters accumulate PM, it builds up backpressure that has many negative effects such as increased fuel consumption, engine failure, and stress in the filter. To prevent these negative effects, the DPF has to be regenerated by burning trapped PM. There are subsequently two types of regeneration processes of DPFs commonly referred as active regeneration and passive regeneration. Active regeneration can be periodically applied to DPFs in which trapped soot is removed through a controlled oxidation with O2 at 550 _C or higher temperatures (Jeguirim et al. 2005). In an active regeneration of DPF, PM is oxidized periodically by heat supplied from outside sources, such as an electric heater or a flame-based burner. The burning of PMs, captured in the filter, takes place as soon as the soot loading in the filter reaches a set limit (about 45 %) indicated by pressure drop across the DPF. The higher regeneration temperature and large amount of energy for heat supply are serious problems for active regeneration. While the temperatures as high as melting point of filter generates to failure of DPF, the necessity of energy for heating increases the production
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cost of system due to complex supplements. These negative effects regard the active regeneration as being out of preference. Unlike in the active regeneration, in passive regeneration of DPF, the oxidation of PMs occurs at the exhaust gas temperature by catalytic combustion promoted by depositing suitable catalysts within the trap itself. PM is oxidized by an ongoing catalytic reaction process that uses no additional fuel. Under a temperature range between 200 and 450 _C, small amounts of NO2 will promote the continuous oxidation of the deposited carbon particles. This is the basis of the continuously regenerating trap (CRT) which uses NO2 continuously to oxide soot within relatively low temperatures over a DPF (York et al. 2007, Allansson et al. 2002). In passive regeneration, the entire process is very simple, quiet, and effective and fuel efficient, that is, neither the vehicle operator nor the vehicle’s engine management system have to do anything to induce the regeneration of the DPF. In this process generally, a wall flow silicon carbide filter is used with DOC, sophisticated engine management system and sensors. DOC upstream of DPF increases the ratio of NO2 to NO in the exhaust and lowers the burning temperature of PMs. NO2 provides a more effective oxidant than oxygen and so provides optimum passive regeneration efficiency (Johansen et al. 2007). The wall flow SiC filter is one of the most widely used filters as DPF worldwide. Since the regeneration occurs at high exhaust temperatures, DOC has to be used upstream this filter. Catalyzed DPFs (CDPF) housing the DOC formulation on the DPF itself can eliminate this obligation. In this system, there is not any DOC or any aftertreatment systems upstream DPF and all reactions take place in the CDPF. CDPF in which Pt is used as catalyst has the same conversion efficiency compared to wall flow SiC filter. With CDPFs, the oxidation temperature of soot can be decreased. In addition to the oxidation occurring in DPF may be realized at lower temperatures, the conversion rate can be further increased using biodiesel or fuel additives (Lamharess et al. 2011). Although the regeneration is one of major problem for DPFs, nowadays many studies and researches have been carried out for solving this problem and decreasing the oxidation temperatures of soots.
20.3 Selective catalytic reduction (SCR) SCR is another technology to reduce NOx emissions and especially improved for highduty vehicles. Because of low exhaust temperature, it has not been used widely for lightduty vehicles. But nowadays, it is being developed for light-duty passenger vehicles and a few lightduty vehicle manufacturers like Audi have been using this technology in their automobile. SCR is used to minimize NOx emissions in the exhaust gas to utilize ammonia (NH3) as the reductant 85
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(Biswas et al. 2009). Water and N2 are released as a result of catalytically conversion of NOx in the exhaust gas. Due to the toxic effects of NH3 and to prevent burning of NH3 in the warm atmosphere before the reaction, NH3 is provided from an aqueous solution of urea (MorenoTost et al. 2008; Hamada and Haneda 2012). This solution is obtained from mixing of 33 % urea (NH2)2CO and 67 % pure water by mass. In order to get high efficiency, the amount of NH3 stored on the SCR catalyst should be controlled as high as possible. However, high NH3 storage can lead to undesired ammonia. Ammonia slip is generally avoided or minimized by the precise injection of urea based on the required ammonia (Majewski and Khair 2006). By spraying solution on exhaust gas, as a result of the pure water vaporization, solid urea particles begin to melt and thermolysis takes place as seen in Eq. (4) (Koebel et al. 2000; Yim et al. 2004).
NH3 and isocyanic acid are formed in thermolysis reaction. NH3 takes part in the reactions of SCR catalyst, while the isocyanic acid is converted with water in a hydrolysis reaction (Koebel et al. 2000). Further NH3 is produced by this hydrolysis [Eq. (5)].
Thermolysis and hydrolysis reactions occur more rapidly than SCR reactions. Two molecules of ammonia are produced in a molecular urea by reactions of thermolysis and hydrolysis (Chi and DaCosta 2005). The efficiency of reactions to produce NH3 from urea depends largely on exhaust gas temperature. While the temperature of urea melting is 133 _C, it is indicated in different researches that thermolysis starts at 143, 152, 160 _C (Linde 2007; Oh et al. 2004; Sun et al. 2001; Schaber et al. 2004; Calabrese et al. 2000). Although the conversion of aqueous urea solution to NH3 is started at the time of injector spraying, full conversion is not completed by the entrance of the catalyst. Half of the total amount of decomposition of urea to NH3 is obtained up to entrance of catalyst. Thus, conversion efficiency is theoretically 50 % to the catalyst entrance. However, the implementation of the hydrolysis reaction in the gas phase before the entrance of catalyst increases conversion efficiency due to exhaust temperature (Koebel et al. 2000; Chi and DaCosta 2005). After the thermolysis and hydrolysis, the chemical reactions which occur in SCR catalyst are shown below.
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The rate of SCR reactions may be listed as ‘‘7t_h_2 th=t_h_1; else th=t-h_2; end t1=d*sqrt(3*pw/(s_t_pis/2.5)); nr=d/(10*t1); b1=th*1.2; b=0.4+t1; t3=0.03*d+b+4.5; t4=0.35*t3; f=p_gas*pi*((d/1000)^2)/4; r=f/10; l_skirt=r/(1.5*d); l_total=l_skirt+b1+((nr+(nr-1))*t1); x=0.04*d; l1=0.45*d; do=f/(100*36); di=0.6*do; mom=(f*d)/8; z=(pi/32)*(((do^4)-(di^4))/do); s_all=mom/z; l_con=2*s; r_crank=s/2; w=(2*pi*rpm)/60; n=l_con/r_crank; f_in=.46452*(w^2)*(r_crank/1000)*(1+(1/n)); fl=f-f_in; dob=sqrt(fl/(12.5*1.5)); dos=fl/(26.83*77.28); dis=0.6*dos; dib=dob-22; t_crankweb=0.32*d;
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w_crankweb=1.125*dib+12.5; d_s=t_crankweb/0.6; h_ch=.95*d; t_lsw=0.09*d+2; t_ca=.03*d+4.2; s_tl=(lec*E*100)/((1-.25)*2); s_tot=s_tl+50; t_liner=(.5*(p_gas*(10^-6))*d)/(s_tot/3); disp('piston dimensions'); fprintf('Th= ') disp(th) fprintf('t1= ') disp(t1) fprintf('t2= ') disp(t1) fprintf('b1= ') disp(b1) fprintf('b2= ') disp(t1) fprintf('t3= ') disp(t3) fprintf('t4= ') disp(t4) fprintf('skirt length= ') disp(l_skirt) fprintf('piston length= ') disp(l_total) disp('piston pin dimensions') fprintf('outer diameter= ') disp(do) fprintf('inner diameter= ') disp(di) fprintf('allowable stress= ') disp(s_all) disp('connecting rod dimensions') fprintf('length from pin center to big end center= ') disp(l_con) fprintf('outer diameter of big end= ') disp(dob) fprintf('inner diameter of bid end= ') disp(dib) fprintf('outer diameter of small end= ') disp(dos) fprintf('inner diameter of small end= ') disp(dis) disp('crank shaft dimensions') fprintf('thickness of crank web= ') disp(t_crankweb) fprintf('width of crank web= ') disp(w_crankweb) fprintf('shaft diameter= ') disp(d_s) disp('cylinderhead dimensions') fprintf('height of cylinder head= ') disp(h_ch) fprintf('thickness of lower support wall= ') disp(t_lsw) fprintf('thickness of cooler area= ') disp(t_ca) fprintf('thickness of cylinder liner ') disp(t_liner)
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34 Geometry Modeling using SolidWorks 34.1 Piston Head and Pin
Figure 34-1 3D view of piston
Figure 34-2 section of 3D modeling of piston
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Figure 34-3 3D plane view of piston
Figure 34-4 3D Piston pin
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34.2 Connect rod & connect rod bottom
Figure 34-5 3D connecting rod view
Figure 34-6 3D Section of connecting rod
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34.3 Crank shaft
Figure 34-7 3D Crank shaft view
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34.4 Assembly parts of modeling
Figure 34-8 3D assembly model engine
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Figure 34-9 3D section of assembly model engine
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Conclusions
The aim of this Thesis is to introduce to the interesting world of internal combustion engines and to describe what Internal Combustion Engine is. What are its main components and structure. How the engine indeed operates. Also, to design a real engine, having into account all necessary calculations concerning with kinematics, dynamics and strength calculation of basic details. Another purpose of the project is to define the proper materials for each part. Next to that we make 2D and 3D drawings on SolidWorks and animation of working Internal Combustion Engine for two strokes one cylinder.
In this project, the main parts of the engine piston, connecting rod and crankshaft are designed using theoretical calculations for the given engine specifications. The designed parts are modeled and assembled in 3D modeling software Pro/Engineer. The materials used are Aluminum for piston, Cast Iron for the Connecting rod and crankshaft. Also, we are use MATLAB software to code the equations calculations to get it simple for other whom come to get this project.
First, we went to development the double acting engine by using exhausting to act as steam engine, but the calculations didn't see it works, so we decide to study the optimum design of 2-stroke diesel engine to improve our knowledge with designs machine’s parts. We prefer to study the WHRS systems and know each system, specific fuel consumption, Life time of machines, environment emission, auxiliary systems and finally the design of engine parts to get the better and perfect design.
Addition we made the prototype using similar materials usually used in engines by helping the AAST workshops
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References
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24. Machinery, Association of Computing. ACM 2007 Plenary Speakers. ACM. [Online] [Cited: 3 22, 2018.] http://www.acm.org/. 25. LLEWELLYN V. LUDY, M.E. A THOROUGH AND PRACTICAL PRESENTATION OF MODERN STEAM ENGINE PRACTICE. s.l. : AMERICAN SOCIETY OF MECHANICAL ENGINEERS. 26. KRAUS, ALLAN D. Heat Exchangers. Akron, Ohio : University of Akron. 27. KHURMI, R.S. and GUPTA, J.K. A TEXTBOOK OF MACHINE DESIGN. 25. NEW DELHI : S Chand, 2005. CH. 32. 8121925371. 28. Jones, Peter. The Mould Design Guide. Shawbury, Shrewsbury, Shropshire, SY4 4NR, United Kingdom : Soft-backed ISBN: 978-1-84735-088-6 , 2008. 29. Hills, Richard L. power from Steam. Cambridge University Press : pp. 63, 66. ISBN 0-521-45834-X., 1989. 30. Ferdinand, Meinertz Mark. Double-acting two-stroke internal-combustion engine. [Online] 1949. [Cited: 11 3, 2017.] http://freepatentsonline.com/2488093.html. 31. Erumban*, Abdul Azeez. LIFETIMES OF MACHINERY AND EQUIPMENT. EVIDENCE FROM DUTCH MANUFACTURING. 2008. 32. Enrico Mattarelli, Giuseppe Cantore and Carlo Alberto Rinaldini. Advances in the design of two-stroke, high speed, compression ignition engines. [Online] 33. engines, Manual of Cat®. DIESEL FUELS & DIESEL FUEL SYSTEMS. 34. El-Gohary, M. Morsy. Finite element analysis of marine diesel engine components . Alexandria Engineering Journal. 2008, Vol. 47, 4, 307-316. 35. Edgar, Smith C. A Short History of Naval and Marine Engineering. Cambiradge University Press : s.n., 2013. pp. 334-336. 9781107672932. 36. D., John. The Fleet Submarine in the U.S. Navy: A Design and Construction History. london : s.n., 1979. pp. 48-50,62-63,210. 0-85368-203-8. 37. Belaire, Richard C. Reducing the starting torque of double-acting Stirling engines. [Online] 1977. [Cited: 11 3, 2017.] http://freepatentsonline.com/4026114.html. 38. Baranescu, Bernard Challen and Rodica. Diesel engine reference book second edition.
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