Optimizing diesel engine parameters for emission reduction ... - NOPR

Indian Journal of Engineering & Materials Sciences Vol. 12, December 2005, pp. 505-514

Optimizing diesel engine parameters for emission reduction using Taguchi method: Variation risk analysis approach – Part II M Nataraj*, V P Arunachalam & N Dhandapani Mechanical Engineering, Government College of Technology, Coimbatore 641 013, India Received 29 July 2004; accepted 1 August 2005 Taguchi parameter design research methodology allows one to make products or processes robust to uncontrollable noise factors and will also reduce the number of experiments to be carried out to arrive an optimized system. The main objective of this work is to study the various operating parameters of diesel engine to propose modified engine parameter (optimum) settings for reduction in NOX, HC, CO and smoke concentrations simultaneously in diesel emission by applying Taguchi parameter design concept. Taguchi L18 (21×37) quality design concept mixed orthogonal array has been used to determine the S/N ratio (dB), analysis of variance (ANOVA) and F0 test values for recognizing most significant engine operating parameters that influence exhaust emission. The experimental results give an idea about how the variations in engine settings like nozzle spray holes, piston-to-head clearance, nozzle protrusion, injection control pressure, start of injection timing and swirl level alter the pollutant (NOX, HC, CO and smoke) intensity in emission. Considering these significant engine-operating parameters, verification of the improvement in the quality characteristics for emission reduction has been done through confirmation test with reference to the chosen initial or reference parameter settings. These confirmation test results prove that the optimal combination of diesel engine parameters obtained from the investigation reducing the pollutant levels in exhaust emission in reality. IPC Code: F02B

The feasibility of using the Taguchi method to optimize selected engine design/operating parameters for low emission was investigated using a Dhandapani Foundary (DPF) diesel engine in Part-I1. In order to examine whether the variation in key combustion parameters have the same effect and influence on every diesel engine of any make, the same research methodology was adopted on TEXVEL diesel engine with the same hardware configurations. Extensive research into the mechanisms governing diesel combustion and emissions has already been reported2,3. The vast amount of investigation done in the diesel combustion and emissions still not well understood due to the complex interrelationships that exist between combustion system parameters and fuel injection system parameters. Taguchi developed multivariate experimental techniques4,5 using orthogonal design arrays that allow one to isolate the effect of a single parameter on a particular response characteristic. Taguchi methods have been most extensively used in industrial and manufacturing sectors; their application to investigate diesel combustion and emissions has been very limited6. The ___________ *For correspondence (E-mail: [email protected])

objective of this research study was to examine the effects of changes in several key combustion and fuel injection system parameters on engine exhaust using Taguchi methods to have a better understanding of how these changes affect the diesel combustion and emission formation processes. Experimental Procedure Test set-up and experimentation

A test rig has been installed for experimentation to measure the NOX, CO, HC and smoke levels of engine emissions. The rig comprises of fuel tank, manometer, air tank, electronic temperature measuring unit, fuel injection system, and exhaust gas analyzer. A single cylinder, direct injection TEXVEL engine having bore (114 mm) and stroke (140 mm) was taken for investigation. Fig. 1 shows the experimental test set-up put in the research laboratory at Government College of Technology, Coimbatore. Steady state tests were conducted on diesel engine with 18 different hardware configurations at 40% and 60% of maximum load during the experiment. The injector unit was removed often to change the nozzle/nozzle protrusion. The trials associated with the change of piston-to-head clearance (gasket change) were tested in random order to save testing

INDIAN J. ENG. MATER. SCI., DECEMBER 2005

506

time as well as avoid introducing any noise otherwise would be caused by hardware change. Extra precautions were taken to ensure that each part was re-installed according to specifications. A total of 288 data points were recorded in this experiment with the help of exhaust gas analyzers (Kane-May 900 combustion analyzer for measuring NOX level, NPMSM11B meter for measuring smoke level and NPMCH1 exhaust gas analyzer for measuring CO and HC levels). NOX, CO, HC and smoke emission responses were obtained for the 18 engine configurations. The response of the system is measured using Eq. (1) i =n

Fig. 1—Diesel engine test rig.

S/N ratio (dB)STB = -10 log [1/n

∑Y 2] i =1

Table 1⎯Parameter with Levels

Parameters

1

A. Number of holes 3 holes B. Piston-to-head 1.2 clearance C. Nozzle Potrusion 2.5 D. Start of Injection25.3 Timing bTDC F. Injection Control 160 Pressure G. Swirl Level ¼ open (Throttle Position)

i

where, n is number of trials and Yi are the emission data for each trial.

Levels 2

3

4 holes

-

-

1.4

1.8

mm

3.4 28.3 bTDC

4.35 31.3 bTDC

mm

170

180

atm

½ open

Full open

Unit Parameter selection

deg.

The engine parameters that are most likely to influence diesel exhaust emissions are nozzle spray holes, piston-to-head clearance, nozzle protrusion, injection control pressure, start of injection timing and swirl level7. Selection of factor levels and orthogonal array

Due to the non-linearly of the diesel exhaust emissions over the normal speed and load operating

Table 2⎯Mixed orthogonal arrays [L18 (21×37)] 1 Column No.

No. of holes

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

Three Three Three Three Three Three Three Three Three Four Four Four Four Four Four Four Four Four

... (1)

2 Piston-tohead clearance (mm2)

3 Nozzle protrusion (mm)

4 Injection control pr. (atm)

5 Start of inj. timing (degree)

6 Swirl level

1.2 1.2 1.2 1.4 1.4 1.4 1.6 1.6 1.6 1.2 1.2 1.2 1.4 1.4 1.4 1.6 1.6 1.6

2.9 3.95 4.0 2.9 4.0 4.0 2.9 3.95 4.0 2.9 3.95 4.0 2.9 3.95 4.0 2.9 3.95 4.0

160 170 180 160 170 180 170 180 160 180 160 170 170 180 160 180 160 170

25.3bTDC 28.3bTDC 31.3bTDC 28.3bTDC 31.3bTDC 25.3bTDC 25.3bTDC 28.3bTDC 31.3bTDC 31.3bTDC 25.3bTDC 28.3bTDC 31.3bTDC 25.3bTDC 28.3bTDC 28.3bTDC 31.3bTDC 25.3bTDC

Low Medium High Medium High Low High Low Medium Medium High Low Low Medium High High Low Medium

NATARAJ et al.: DIESEL ENGINE PARAMETERS FOR EMISSION REDUCTION USING TAGUCHI METHOD

range of the engine, two levels for nozzle spray holes (A) and three levels for the remaining parameters was considered. Control parameters and their levels are given in Table 1. L18 [21 × 37] mixed orthogonal array shown in Table 2 was selected for the experimental investigation. “smaller-the-better” is being taken as a quality characteristic, since the objective function is to minimize NOx, CO, HC and smoke emission. Statistical analysis

A statistical analysis was done for the experimental data obtained which are shown in Table A2 from the L18 experiment. The average emission responses and S/N ratios were calculated for each control factor. Analysis of variance (ANOVA) was performed to identify the most significant control parameters and to quantify their effects on NOX, CO, HC and smoke. Table 3 shows variance (Fo) and percentage of contribution ratio (ρ).

507

Response curve analysis

Response curve analysis is aimed at determining influential parameters and their optimum levels. Figs 2 and 3 show significant effects for each emission response at each factor level for 40% Wmax and 60% Wmax respectively. The S/N ratios for the different emission responses were calculated at each factor level and the average effects were determined by taking the total of each factor level and dividing by the number of data points in that total. The greater difference between the levels, the parametric influence will be much. The parameter level having the highest S/N ratio corresponds to the parameters setting indicates lowest emission. Referring (Fig. 2) the response curve at 40% Wmax for the CO emissions, the highest S/N ratio was observed at nozzle spray holes (4 holes), piston-tohead clearance (1.8 mm), nozzle protrusion (4.35 mm), start of injection timing (25.3 bTDC), injection

Table 3—ANOVA results for 40% and 60% of Wmax

CF F0 A B C D F G (e)

CO (%) ρ%

102.5* 0.7 4.2† 16.0 ! 6.0• 64.4‡ -

35.2 0.5 2.9 11.0 4.1 44.2 2.1

F0

40% of Wmax HC (ppm) Smoke (HSU) NOX (ppm) F0 F0 ρ% ρ% ρ%

5.1* 3.5 ! 1.9 1.6 4.5‡ 0.5 -

14.6 19.9 11.1 9.1 25.5 2.7 17.1

25.3* 1.7 0.2 0.8 1.4 9.9‡ -

42.8 5.8 0.5 2.8 4.6 33.4 10.2

12.1‡ 1.0 0.2 17.8* 0.04 3.5 ! -

19.2 3.1 0.5 56.5 0.1 11.1 9.5

F0

CO (%) ρ%

20.8‡ 1.5 1.3 1.0 5.9 ! 40.6* -

F0

16.3 2.4 2.0 1.6 9.3 63.7 4.7

(e)-pooled error [e1+e2] * Most significant ‡ More significant ! Significant • Less significant

60% of Wmax HC (ppm) Smoke (HSU) NOx (ppm) F0 F0 ρ% ρ% ρ%

12‡ 1.9 1.4 1.2 4.8 ! 17 * †

Fig. 2—Response curves for 40% Wmax.

16.9 5.4 4.0 3.4 13.6 48.2 8.5

29.0* 4.1• 0.1 0.4 4.2 ! 28.6‡ -

Very less significant

26.5 7.4 0.1 0.7 7.7 52.2 5.5

11.3‡ 0.3 0.4 20.0* 0.2 1.0 -

18.5 1.0 1.3 65.6 0.6 3.2 9.8

508


Fig. 3—Response curves for 60% Wmax.

control pressure (170 mm) and swirl level (full throttle open). Similarly the optimum parameter setting for lowest HC emissions were found to be a nozzle spray holes (4 holes), piston-to-head clearance (1.8 mm), nozzle protrusion (4.35 mm), start of injection timing (25.3 before TDC), injection control pressure (170 atm) and swirl level (full throttle open). Smoke emissions were lowest at nozzle spray holes (4 holes), piston-to-head clearance (1.4 mm), nozzle protrusion (4.35 mm), start of injection timing (25.3 before TDC), injection control pressure (160 atm) and swirl level (full throttle open). NOX emissions were lower at nozzle spray holes (3 holes), piston-to-head clearance (1.2 mm), nozzle protrusion (3.4 mm), start of injection timing (25.3 before TDC), injection control pressure (180 atm) and swirl level (full throttle). Referring (Fig. 3) the response curve, looking 60% Wmax for the CO emissions, the highest S/N ratio was observed at nozzle spray holes (4 holes), piston-tohead clearance (1.8 mm), nozzle protrusion (4.35 mm), start of injection timing (25.3 before TDC), injection control pressure (170 atm) and swirl level (full throttle open). Average HC emission was lowest for nozzle spray holes (4 holes), piston-to-head clearance (1.8 mm), nozzle protrusion (4.35 mm), start of injection timing (25.3 bTDC), injection control pressure (170 mm) and swirl level (full throttle open). Smoke emission were lowest at nozzle spray holes (4 holes), piston-to-head clearance (1.8 mm), nozzle protrusion (2.5 mm), start of injection

timing (25.3 before TDC), injection control pressure (160 atm) and swirl level (full throttle open). NOX emissions were lowest at nozzle spray holes (3 holes), piston-to-head clearance (1.2 mm), nozzle protrusion (3.4 mm), start of injection timing (25.3 before TDC), injection control pressure (170 atm) and swirl level (full throttle open). Finding optimum parameter settings

Table 4 summarize the optimum parameter setting determined for each response at 40% Wmax and 60% Wmax. Note that the term optimum reflects only the optimal combination of the parameters defined by this experiment. Summary table needs to be constructed, in which only the level sums of SN ratio of significant factors appear. The optimum setting is determined by choosing the level with the highest SN ratio. Control factor A is most significant in CO, HC, and smoke than NOX. However, since factor A is less meaningful in HC, smoke emission than CO emission. So the optimum condition is A2. In respect of control factor B and C; factors B and C are significant only in HC emission and CO emission respectively. Hence B3 and C3 are predicted as the optimal levels for the parameters B and C. For factors D, F and G, more than one response is significant. So it is confirmed that D1, F2 and G3 are the optimal conditions for parameter D, F and G respectively at 40% maximum load. Same combination of parameters was obtained in a similar way for the 60% maximum load. Therefore, the optimal combinations of control factors


509

Table 4—Overall summary table for optimal conditions

Control Factor Level

1 2 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3

A

B

C

D

F

G

Sum of signal-to-noise ratio for 40% Wmax CO HC Smoke NOX A*G‡D! D*A‡ ‡ ! ‡ B A* G A*F G! F•C†

Parameter level for optimal emission

Sum of signal-to-noise ratio for 60% Wmax HC Smoke NOX A*G‡ G*A‡ G*A‡F ! D*A‡ F ! C• F ! B•

Parameter level for optimal emission

115.52 167.06

A2

54.3 113.17

A2

55.53 93.62

19.01 50.54

61.54 38.86

31.05 50.78 67.32 87.73 95.41 99.71 104.1 97.27 81.21 98.01 98.68 85.89 67.89 101.26 113.46

CO

32.48 72.48 44.19 10.45 26.81 32.3

25.78 35.07 39.56

G3

Table 5— Baseline and optimum engine parameter combinations Baseline

Nozzle spray hole Piston-to-head clearance Nozzle protrusion Start of inj. timing Inj. control pr. Swirl level

Parameter settings Optimized

3 holes 1.4 mm 3.4 mm 28.3 before TDC 170 atm Full throttle open

4 holes 1.8 mm 4.35 mm 25.3 before TDC 170 atm Full throttle open

Table 6—Baseline versus optimized engine emission Emissions

CO (%)

Emission data for 40% Emission data for 60% Wmax Wmax Baseline Optimized Baseline Optimized 0.28

HC (ppm) Smoke (HSU)

70 71

(No)x (ppm)

570

0.06, 0.06, 0.06 20,10, 10 32, 33, 32 510, 512, 510

110 86

0.09, 0.08, 0.08 20, 20, 10 51, 52, 51

690

633, 633, 635

0.52

are A2 B3 C3 D1 F2 G3 for minimized concentration of NOX, CO, HC, and smoke in the diesel engine emission both at 40% and 60% of Wmax. Results and Discussion The optimum parameter combinations are differing from base line engine parameter settings. The baseline

B3

C3 45.53 37.96 16.93

D1

F2

59.84 40.58

65.51 72.65 85.67

C3 45.85 38.99 15.57

20.88 41.1 17.98 18.31 25.69

B3

54.06 74.79 38.61 1.01 82.51 83.95

(e)-pooled error [e1+e2] * Most significant ‡ More significant ! Significant • Less significant

Parameters

86.17 137.66

63.41 96.42 64.00 34.07 89.36 100.4 †

24.21 22.1 15.67 7.29 26.9 27.8

D1

F2

G3

Very less significant

and optimum parameter combinations are shown with levels in Table 5. The results point out that the parameter combinations are not changed with load variation. Table 6 shows that the emission data for baseline engine and optimized engine. Fig. 4 shows visually the composition of CO, HC, NOX and smoke in emissions for the baseline and optimized engine at 40% Wmax and 60% Wmax. CO, HC and smoke level in emission varies proportionally with the load for both baseline and optimized engine. NOX emission was not reduced that much whatever be the load variation. Noticed that there was remarkable reduction in emission with load variation for the optimized engine when compared to baseline engine for the CO, HC and smoke. Performance analysis

Fig. 5 demonstrates the comparative study on performance evaluation of base line engine versus optimized engine. It was made clear that the performance of the optimized engine is better than the base line engine for the entire load range from minimum to maximum. Also proves that Taguchi parameter design concept is more powerful and efficient tool for reducing the concentration of pollutants in the exhaust emission of diesel engine.

510


Fig. 4a—CO Emission versus load conditions.

Fig. 5b—Brake power versus indicated thermal efficiency.

Fig. 4b—HC Emission versus load conditions.

Fig. 5c—Brake power versus specific fuel consumption.

Fig. 4c—Smoke emission versus load conditions.

Fig. 4d—Nox emission versus load conditions.

Fig. 5d—Brake power versus CO emission.

Fig. 5a—Brake power versus brake thermal efficiency.

Fig. 5e—Brake power versus HC emission.


511

parameter design concept is more powerful and efficient tool for reducing the concentration of pollutants in the exhaust emission of diesel engine. Acknowledgements The authors would like to thank Thiru M. Rajasakar, Faculty of Thermal Engineering Department, Government College of Technology, Coimbatore, for the professional and technical support rendered during this study. Fig. 5f— Brake power versus smoke emission

References 1

Nataraj M, Arunachalam V P & Dhandapani N, Indian J Eng Mater Sci., 12 (2005) 169-181. Gill A P, SAE Paper No. 880350, (1988) 461-473. Hunter C E, Cikanek H A & Gardner T P, J Eng Gas Turbines Power, 111 (1989) 916-929. Antony J, Int J Adv Manufact Technol, 17 (2001) 134-138. Sung H Park, Robust design and analysis for quality engineering (Chapman & Hall India, London), 1996. Hames R J, Merrion D F & Borman G L, SAE Paper No. 710671, (1971) 738-751. Ganesan V, Internal combustion engines (Tata McGraw-Hill Publising Company, New Delhi), 2002. Ross P J, Taguchi technique for quality engineering (McGraw-Hill, New York), 1988. Logothetis N, Total quality management-from Deming to Taguchi and SPC (Printice-Hall International, UK), 1992.

2 3 4 5 6 7 Fig. 5g—Brake power versus NOX emission.

8

Conclusions The feasibility of using the Taguchi method to optimize selected diesel engine design parameters for low emissions was investigated using a single cylinder, research diesel engine. The conclusions from this work are summarizes as follows: The Taguchi method was found to be an efficient technique for quantifying the effects of engine design and operating parameters on exhaust emissions. CO emission level was influenced by nozzle spray holes, swirl level, start of injection timing, injection control pressure and nozzle protrusion. HC emission level was influenced by nozzle spray holes, injection control pressure, piston-to-head clearance, nozzle protrusion and swirl level. Smoke emission level was influenced by nozzle spray holes, swirl level, injection control pressure and piston-to-head clearance. NOX emission level was influenced by start of injection timing, nozzle spray holes and swirl level. NOX, CO, HC and smoke emission results obtained from the confirmation experiments fell in good agreement with the predicted results. The parameter settings of optimized engine were not found in any of 18 trial runs of the L18 orthogonal array. 18 trials were conducted to find the optimized parameter settings. The performance of the optimized engine is better than the base line engine and also proves that Taguchi

9

Appendix Predicting emissions at optimum conditions for 40% Wmax The parameter setting for the optimum conditions are shown in following table: Control Factor A B C D F G

Parameters No. of holes Piston-to-head clearance Nozzle Protrusion Start of Injection Timing Injection Control Pressure Swirl Level

(Four holes) (1.8 mm) (4.35 mm) (25.3°bTDC) (170 atm) (Full throttle open)

Levels A2 B3 C3 D1 F2 G3

To estimate the emission responses at the optimum conditions, Eqs (A1) and (A2) is used; Effective number of replications (neff) neff = N / [1+(Total D.O.F associated with items used in μˆ estimate)] … (A1) where N is number of trial runs; and μˆ is Mean Estimate of error variance (Ve) Ve =

Pooled Variation of non-significant sources Pooled degrees of non-significant sources

… (A2)

Estimation of predicted confidence interval (CI) The confidence interval8,9 of the above-predicted estimation is calculated using the following equation.


512 CI = t (Φ,α )

Ve neff

… (A3)

In calculating the estimates, only the parameters with a strong effect on the emission response are used to allow for experimental error (variance). For CO emission at 40% Wmax The S/N ratios for each emission response level are listed in Table A4. For carbon monoxide (CO) emission, the parameters with the strongest effects were;

⎡ 3.347 ⎤ = 23.42 ± 3.055 ⎢ ⎥ 3 ⎦⎥ ⎣⎢ = 20.19 to 26.65 The confirmation test is conducted to check whether the obtained optimal condition (A2 B3 C3 D1 F2 G3) falls within the Confidence Interval. The CO emission data’s are 0.06, 0.06, 0.06 SN ratio for these observations (CO emission) is i =n

SN ratio(dB)

= -10 log [1/n

∑ Yi ]. 2

i =1

Strong effects: A2 D1 G3 The average S/N ratio for CO, i.e., T was determined using the values shown in Table A3 for nozzle spray holes as;

= -10 log

⎡1 2 2 2 ⎤ ⎢ 3{0.06 + 0.06 + 0.06 }⎥ ⎣ ⎦

= 24.44 dB

115.52 +167.06 ( 282.58) = T = = 31.40 18 18 μˆ = μˆ (A2D1G3) = A2+D1+G3 – 2 T

The SN ratio value is contained within the 99.995% confidence interval obtained. So the optimum condition is confirmed by a confirmation test.

=

167.06 104.1 113.46 + + −2(31.40)= 23.42 9 6 6

neff

=

18 =3 1+ (1+ 2 + 2)

Ve

⎡S S S S S ⎤ = ⎢ B + C + F + e1 + e 2 ⎥ 12 ⎣18 18 18 18 18 ⎦

Similar calculations were made for other emissions in 40% and 60% of maximum load using the following strong effects; 40% Maximum load Strong effects for hydrocarbon (HC) Strong effects for smoke Strong effects for Oxides of Nitrogen(NOX)

: A2 B3 C3 D1 F2 : A2 B2 G3 : A1 D1 G3

60% Maximum load ⎡ 37.28 219.31 310.93 108.12 47.34 ⎤ = ⎢ + + + + 12 18 18 18 18 ⎥⎦ ⎣ 18

Strong effects for carbon monoxide (CO) Strong effects for hydrocarbon (HC) Strong effects for smoke Strong effects for oxides of nitrogen(NOX)

= 3.347 A 99.995% confidence interval for CO was determined by; t (Φ,α) = t (12, 0.005) = 3.055 (from t-Distribution Table)

μˆ ±t(Φ,α) = 23.42±t(12,0.005) ⎡ Ve ⎤ = 23.42 ± 3.055 ⎢ ⎥ ⎣⎢ neff ⎥⎦

: A2 F2 G3 : A2 B3 F2G3 : A2 B3 F1 G3 : A1 D1

Table A1 illustrate a comparison of the actual S/N ratios computed from the measured emission responses and the predicted S/N ratios computed using Eqs (A1)-(A3). The ranges of the predicted S/N values were computed for 99.995% confidence interval about the mean. In the usual course of events, all three-emission responses fell within their predicted ranges, which indicated good reproducibility and confirmed that the experiment results were valid.

Table A1—Comparison of predicted and actual S/N ratios using optimum setting for 40% Wmax Emissions

CO (%) HC (ppm) Smoke (HSU) NOX(ppm)

For 40 % Wmax Predicted range of S/N ratio Actual S/N Ratio ( 99.995% confidence ) 20.19 to -21.12 to -32.69 to -54.35 to

26.65 -7.04 -27.77 -49.83

24.44 -23.01 -30.19 -54.16

For 60 % Wmax Predicted range of S/N ratio ( 99.995 % confidence ) 16.37 to 24.49 -25.5 to -9.78 -34.36 to -31.25 -56.18 to -54.5

Actual S/N ratio 21.57 -24.77 -34.21 -56.03


513

Table A2—Experimental data AT 60% W max

AT 40% W max CO data (%)

Run No.

HC data (ppm)

Smoke data (HSU)

NOX data (ppm)

CO data (%)

Trial 1 (X1)

Trial 2 (X2)

Trial 1 (X1)

Trial 2 (X2)

Trial 1 (X1)

Trial 2 (X2)

Trial 1 (X1)

Trial 2 (X2)

Trial 1 (X1)

1

0.41

0.41

50

60

63

72

480

478

2

0.26

0.26

50

50

78

78

411

388

3

0.25

0.26

40

30

71

72

757

4

0.11

0.12

10

10

42

45

5

0.12

0.12

20

20

41

42

6

0.34

0.36

50

50

67

7

0.17

0.17

40

50

8

0.4

0.41

30

30

9

0.19

0.18

20

10

0.15

0.16

11

0.06

0.04

12

0.12

13

HC data (ppm)

Smoke data (HSU)

NOX data (ppm)

Trial 2 (X2)

Trial 1 (X1)

Trial 2 (X2)

Trial 1 (X1)

Trial 2 (X2)

Trial 1 (X1)

Trial 2 (X2)

2.71

2.7

130

150

95

95

571

580

0.52

0.53

50

50

79

81

620

625

750

0.53

0.52

60

60

85

88

976

973

531

540

0.12

0.14

20

20

62

63

676

672

467

466

0.35

0.36

20

10

67

70

658

660

71

968

960

1.38

1.36

130

140

91

93

1161

1155

61

58

534

536

0.31

0.3

40

40

64

65

717

715

78

77

961

960

0.5

0.49

60

60

82

83

922

920

20

64

66

372

373

0.27

0.27

20

30

63

68

543

542

40

50

41

43

1059

1056

0.19

0.18

30

30

54

57

1458

1452

40

40

37

36

455

452

0.08

0.08

20

20

43

45

603

590

0.12

10

10

53

58

809

800

0.38

0.39

20

20

81

76

930

935

0.34

0.32

50

70

66

74

760

764

1.46

1.42

120

130

94

91

739

744

14

0.15

0.16

30

30

39

46

1137

1141

0.22

0.24

30

40

58

63

1433

1428

15

0.08

0.08

10

10

29

31

625

620

0.09

0.09

10

10

57

53

782

780

16

0.1

0.1

10

10

31

32

785

793

0.15

0.16

10

10

45

43

1040

1046

17

0.17

0.18

10

10

54

53

753

752

0.87

0.88

60

50

83

82

856

854

18

0.06

0.07

10

10

28

30

732

731

0.09

0.1

10

10

40

42

984

989

Table A3— Average emission responses from L18 experiment Parameters A. No. of holes 1. Three 2. Four B. Piston-to-head clearance (mm) 1. 1.2 2. 1.4 3. 1.8 C. Nozzle protrusion (mm) 1. 2.5 2. 3.4 3. 4.35 D. Start of injection timing (Deg) 1. 25.3 before TDC 2. 28.3 before TDC 3. 31.3 before TDC F. Injection Control Pressure (atm) 1. 160 2. 170 3. 180 G. Swirl Level 1. ¼ throttle open 2. ½ throttle open 3. Full throttle open

CO (%)

For 40% Wmax Smoke HC (ppm) (HSU)

NOX (ppm)

CO (%)

For 60% Wmax Smoke HC (ppm) (HSU)

NOX (ppm)

12.84 18.56

6.17 10.40

2.11 5.62

6.84 4.32

6.03 12.57

9.57 15.30

2.32 4.57

6.65 4.51

15.29 15.68 16.12

5.17 8.46 11.22

2.98 4.50 4.11

6.18 4.95 5.60

7.91 9.08 10.93

10.65 12.08 14.57

3.00 3.05 4.28

5.83 5.23 5.67

14.62 15.86 16.62

6.54 7.48 10.84

3.96 3.60 4.03

5.53 5.86 5.35

7.84 9.43 10.65

10.92 12.11 14.28

3.54 3.34 3.45

5.68 5.87 5.19

17.35 16.21 13.54

10.52 7.87 6.47

4.50 3.54 3.55

7.64 6.50 2.59

10.74 8.41 8.76

13.34 13.34 10.62

3.70 3.26 3.38

7.59 6.33 2.82

16.33 16.45 14.31

5.41 12.08 7.37

4.34 4.20 3.06

5.43 5.63 5.67

9.01 12.47 6.43

10.57 16.07 10.67

4.03 3.68 2.61

5.32 5.77 5.64

11.31 16.87 18.91

6.99 8.89 8.98

1.74 4.47 5.38

4.30 5.84 6.59

0.17 13.75 13.99

5.68 14.89 16.73

1.21 4.48 4.63

5.47 5.10 6.17


514

Table A4—SN ratios for NOX, CO, HC and Smoke data at 40% Wmax

Run No.

CO (%) SN ratio (dB)

AT 40% Wmax HC SMOKE (ppm) (HSU) SN ratio+36 SN ratio+38 (dB) (dB)

NOX (ppm) SN ratio+62 (dB)

CO (%) SN ratio (dB)

AT 60% Wmax HC SMOKE (ppm) (HSU) SN ratio+43 SN ratio+40 (dB) (dB)

NOX (ppm) SN ratio+64 (dB)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

7.74 11.70 11.87 18.78 18.42 9.12 15.39 7.85 14.65 16.19 25.85 18.42 9.63 16.19 21.94 20.00 15.14 23.72

1.16 2.02 5.03 16.00 9.98 2.02 2.88 6.46 9.98 2.88 3.96 16.00 0.32 6.46 16.00 16.00 16.00 16.00

8.39 9.97 4.46 7.42 8.62 2.32 7.43 2.35 10.58 1.51 8.87 3.89 4.36 0.87 6.12 4.06 4.47 4.72

-8.643 5.596 5.596 17.696 8.995 -2.735 10.313 6.107 11.373 14.653 21.938 8.290 -3.168 12.757 20.915 16.189 1.160 20.434

0.06 9.02 7.44 16.98 19.02 0.39 10.96 7.44 14.87 13.46 16.98 16.98 1.05 12.03 23.00 23.00 8.16 23.00

8.80 8.12 4.22 7.43 7.62 2.73 6.90 4.71 9.31 0.74 8.49 4.61 6.60 0.89 6.15 3.63 5.36 4.12

1.39 0.16 0.91 5.23 5.64 1.22 2.51 0.21 1.74 5.53 6.75 3.11 1.08 5.40 8.45 8.03 3.43 8.75

0.45 1.94 1.26 4.08 3.28 0.72 3.81 1.67 3.67 5.11 7.13 2.10 0.68 4.36 5.19 7.13 1.67 7.74