energies Article
Combustion and Emission Characteristics of Coconut-Based Biodiesel in a Liquid Fuel Burner Muhammad Syahiran Abdul Malik 1 , Ashrul Ishak Mohamad Shaiful 2 , Mohd Shuisma Mohd. Ismail 1 , Mohammad Nazri Mohd Jaafar 1 and Amirah Mohamad Sahar 3,4, * 1
2 3 4
*
Department of Aeronautical, Automotive and Ocean Engineering, Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor, Malaysia;
[email protected] (M.S.A.M.);
[email protected] (M.S.M.I.);
[email protected] (M.N.M.J.) School of Manufacturing Engineering, Universiti Malaysia Perlis, Kampus Alam Pauh Putra, 02600 Arau, Perlis, Malaysia;
[email protected] College of Engineering, Design and Physical Sciences, Brunel University London, London UB8 3PH, UK Communication Section, University Kuala Lumpur, British Malaysian Institute, 53100 Gombak, Selangor, Malaysia Correspondence:
[email protected]; Tel.: +60-4-988-5035; Fax: +60-4-988-5034
Academic Editor: Wei-Hsin Chen Received: 29 November 2016; Accepted: 17 February 2017; Published: 1 April 2017
Abstract: This paper presents an investigation on the combustion performance of different Coconut Methyl Ester (CME) biodiesel blends with Conventional Diesel Fuel (CDF) under B5 (5% CME, 95% CDF), B15 (15% CME, 85% CDF), and B25 (25% CME, 75% CDF) conditions. The performances of these fuels were evaluated based on the temperature profiles of the combustor wall and emission concentration of Oxides of Nitrogen (NOx ), Sulphur Dioxide (SO2 ), and Carbon Monoxide (CO). The fuel properties of the CME biodiesel blends were measured and compared with CDF. All tested fuels were combusted using an open-ended combustion chamber at three different equivalence ratios, i.e., lean fuel to air mixture (Φ = 0.8), stoichiometry (Φ = 1.0), and rich fuel to air mixture (Φ =1.2), using a standard solid spray fuel nozzle. The results indicated that CME biodiesel blends combust at a lower temperature and produce less emission in comparison with CDF for all equivalence ratios. Moreover, the increase of CME content in biodiesel blends reduced the temperature of the combustor wall and the emission concentration. Results also proved that the utilization of biodiesel is beneficial to various industrial applications, especially in the transportation sector due to it being environmentally friendly, and serves as an alternative to petroleum diesel fuel. Keywords: CME biodiesel blend; combustion; equivalence ratio; emission
1. Introduction During the past few decades, global attention on biodiesel production and utilization has increased significantly due to the international energy crisis and fossil fuel depletion [1]. The burning of fossil fuels such as petrol, diesel, and coal are among contributors to the emission of hazardous gases such as Oxides of Nitrogen (NOx ), Sulphur Dioxide (SO2 ), and Carbon Monoxide (CO) into the atmosphere [2]. NOx is the binary compound of oxygen and nitrogen, which forms Nitrogen Monoxide (NO), Nitrogen Dioxide (NO2 ), and Nitrous Oxide (N2 O) [3]. NOx and SO2 combine with water vapors in the clouds to produce sulphuric acid (H2 SO4 ) and nitric acid (HNO3 ), which fall back to the earth as acid rain. These compounds turn soil and lakes acidic and corrode building structures [4]. High concentrations of CO in the atmosphere cause harmful effects to human health by reducing the oxygen levels in the blood vessel delivered to body organs and tissues [5]. Biodiesel is a mono alkyl ester of long fatty acids
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derived from renewable lipid feed stocks, such as vegetable oil and animal fats, for use in compression ignition diesel engines [6,7]. Biodiesel is produced by a chemical process called transesterification, i.e., a reaction between triglycerides and alcohol to produce methyl ester and glycerol. Methyl ester is blended with diesel to produce biodiesel, while glycerol is used to produce soaps. Biodiesel can be utilized in pure form or mixed with diesel at any concentration [8]. Biodiesel blends are categorized in the designated form of “BXX”, where “XX” is the percentage of biodiesel in the blend, e.g., “B60” has 60% of methyl ester and 40% of diesel fuel. Biodiesel can be produced from a variety of feedstocks such as palm oil, corn oil, waste cooking oil, and coconut oil. However, biodiesel production depends on the availability of the feedstock in any particular region. In tropical regions such as in Indonesia, Papua New Guinea and the Philippines, coconut is widely available, and hence it is cheaper for the locals to utilize biofuel from this source to generate electricity. The research regarding other potential feedstocks of biodiesel as an alternative fuel has been done by many researchers in the past years. In 2008, Lapuerta [9] and his colleagues investigated the use of biodiesel from waste cooking oil in diesel engines and found that the emission level of CO was reduced but NOx emission increased as compared to that of CDF. This is somewhat different from what Canakci and Van Gerpen [10] obtained in their experiments using B20 and B100 biodiesel blends from soya bean and waste cooking oil in a four cylinder turbo-charged diesel engine. Both biodiesels emit higher NOx than CDF, but CO emission showed a significant reduction. In a study conducted by Jaafar et al. [11] using refined, bleached, and deodorized palm oil (RBDPO) and biodiesel tested in an industrial oil burner with and without air staging, the formation of NOx , CO, and SO2 were found at most reduced by 74.7%, 56.9%, and 68.5%, respectively, compared to that of CDF. The air staging (secondary air) introduced during combustion reduced the emission concentrations even further. Again, in 2014, Jaafar and his co-workers [12] compared the combustion performance of various palm oil biodiesels with CDF in a conventional fuel burner. They found out that increasing the content of palm oil biodiesel in the fuel blend reduces the combustion temperature and emission levels of NOx , SO2 , and CO. This finding is similar to that obtained by Ganjehkaviri et al. [13] in 2016, where various palm oil biodiesel blends with CDF were combusted in an oil burner at three different nozzle flow rates (1.25, 1.50, and 1.75 US gal/h). All palm oil biodiesel blends had lower combustion wall temperatures than CDF for all nozzle flow rates and emit lower NOx and CO emissions. The utilization of coconut oil-based biodiesel in tropical regions has grabbed the attention of researchers around the world to study the benefits of using biodiesel blends from coconut. Coconut oil is produced from copra, the dried flesh of a coconut commonly used in cooking and frying as well as being converted into soaps, health and cosmetic products [14]. The production of coconut oil begins with the drying of copra using heat from the sun or from burning biomass. It is then stored in a warehouse for 2 to 3 months to allow the copra to dry further. The dried copra is then transferred to a copra cleaner to remove any impurities, dirt, and foreign objects before it is broken into small pieces of about 1/16’ to 1/18’ using a high speed vertical hammer. The copra pieces are then cooked inside a steam cooker at 110 ◦ C for 30 min. Then, the copra is transferred into an expeller, where it is subjected to high-pressure oil extraction using a vertical screw and a horizontal screw. The temperature during the extraction process is between 93 ◦ C to 102 ◦ C; between these temperatures, maximum extraction is possible and produces a light coloured oil. The coconut oil undergoes a screening process to remove entrained objects from the oil using chained mounted scrappers. Finally, it is filtered to further remove any impurities inside the oil before being stored inside a storage tank. The total global production of coconut oil in the period between 2014 and 2015 was 3,460,000 tonnes and came mainly from tropical region countries [15]. As illustrated in Figure 1, the Philippines accounted for 45.2% of the total oil production, followed by Indonesia at 28.2%, India at 11.6%, Vietnam at 4.4%, Mexico at 3.8%, and the rest of the world at 6.8%. The average international price for coconut oil decreased from USD 1280 per tonne in 2014 to USD 1131 per tonne during June 2015 and further declined to USD 1039 in August 2015 [15]. The World Bank Commodities Price Forecast predicted that the average price of coconut oil will be USD 1112 in 2016, and it is expected to
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constantly decrease by USD 13 for the next three years. The decrease in the international market price constantly decrease USD 13 foreffect the next three years. The decrease in theininternational market of coconut oil will giveby tremendous to coconut oil-based industries Pacific Island countries price of coconut oil will give tremendous effect to coconut oil-based industries in Pacific Island such as Fiji, Papua New Guinea, and the Solomon Islands, as these countries contribute a substantial countries such as Fiji, Papua New Guinea, and the Solomon Islands, as these countries contribute a amount to the total production of coconut oil in the world. These countries rely on the traditional substantial amount to the total production of coconut oil in the world. These countries rely on the method to produce coconut oil, which requires a large number of low-salaried workers to run the traditional method to produce coconut oil, which requires a large number of low-salaried workers to production, i.e., from collecting to cutting and finally drying the coconut flesh. The reduction run the production, i.e., from collecting to cutting and finally drying the coconut flesh. The reductionin the coconut oil price will affect labour cost rates, thus choking the related industries to become almost in the coconut oil price will affect labour cost rates, thus choking the related industries to become extinct [16].extinct Hence, utilizing as biodiesel provides a new ameans for these island countries almost [16]. Hence, coconut utilizing oil coconut oil as biodiesel provides new means for these island countries to generate their as well as their own power supply. to generate their economy aseconomy well as their own power supply.
Figure Productionof ofcoconut coconut oil countries in 2014 to 2015. Figure 1. 1. Production oilfrom fromdifferent different countries in 2014 to 2015.
Coconut oil-based biodiesel can be used in diesel engines without significant modifications. Coconut [14], oil-based biodiesel canSuryanto be usedet in engines significant modifications. Raghavan Saifuddin et al. [17], al. diesel [18], and Llamas without et al. [19] found that coconut oil Raghavan [14], Saifuddin et al. [17], Suryanto et al. [18], and Llamas et al. [19] found that oil is majorly made up of saturated medium chain fatty acids, especially lauric acid and myristiccoconut acid. is majorly made up of saturated medium chain fatty acids, especially lauric acid and myristic acid. Moreover, coconut oil solidifies at temperatures of less than 24 °C and has a lower energy content ◦ C andahas Moreover, coconut oil solidifies at of temperatures less thanit24 a lower than diesel. Another advantage using coconutofoil is that possesses high cetane energy number,content which than enables it to advantage ignite fasterof than other plant oil However, the viscosity of number, coconut oil is very diesel. Another using coconut oilbiodiesels. is that it possesses a high cetane which enables high, which can cause poor volatilization in the fuel injector system and a poor spray pattern. To it to ignite faster than other plant oil biodiesels. However, the viscosity of coconut oil is very high, overcome thispoor highvolatilization viscosity, coconut is usually heat exchanger before which can cause in theoilfuel injectorheated systemusing and aa poor spray pattern. Tobeing overcome sprayed into the combustion chamber. In another research, Giles [20] found out that coconut-based this high viscosity, coconut oil is usually heated using a heat exchanger before being sprayed into biodiesel can combust properly above 500 °C in a compression ignition diesel engine. He showed the combustion chamber. In another research, Giles [20] found out that coconut-based biodiesel can that coconut-based biodiesel would have shorter ignition delay, equivalently close to diesel at this ◦ C in a compression ignition diesel engine. He showed that coconut-based combust properlyThe above 500 combustion temperature. shorter delay will avoid carbon deposition on the nozzle and piston biodiesel shorter the ignition delay, diesel at this temperature. The shorter valveswould as wellhave as reducing formation ofequivalently NOx and CO. close Otherto researchers found different emission combustion delay willexperiments avoid carbon deposition the nozzle andLiaquat pistonetvalves asinvestigated well as reducing results from their using coconut on biodiesel blends. al. [21] the the utilization of coconut biodiesel blends B5 and B15 in a one cylinder 4-stroke diesel engine at various formation of NO and CO. Other researchers found different emission results from their experiments x throttle settings. Both blends. biodiesels produced higher exhaust gas temperatures andofdecreased CO using coconut biodiesel Liaquat et al. [21] investigated the utilization coconut biodiesel emissions with a slight increase in NO x compared to CDF. Using the same type of diesel engine, blends B5 and B15 in a one cylinder 4-stroke diesel engine at various throttle settings. Both biodiesels Woo [22] and his colleagues studied coconut biodiesels of B25 B40 at different injection timings. produced higher exhaust gas temperatures and decreased COand emissions with a slight increase in NOx Their experimental results indicated that NOx formation was on average 8% and 12% less than that compared to CDF. Using the same type of diesel engine, Woo [22] and his colleagues studied coconut of diesel for the B25 and B40 blends, respectively. biodiesels of B25 and B40 at different injection timings. Their experimental results indicated that NOx A fuel oil burner is a mechanical combustion machine that combines fuel oil with air in the formation on average 8% and 12% less than thatignition of diesel forinthe B25 and B40 blends, respectively. properwas amount before delivering the mixture to the point a combustion chamber [23]. The A fuel oil burner is a mechanical combustion machine that combines oil with air in the combustion of this mixture produces heat for application in industrial boilers to fuel generate electricity proper before in delivering to oil theburner ignition point inisare-emerging combustiondue chamber andamount heater systems buildings.the Themixture interest in technology to the [23]. increase of fuel prices and the need to utilize waste oils, expand renewable fuels, and provide The combustion of this mixture produces heat for application in industrial boilers to generate electricity operational assurance against The curtailments and shortages. Despite the different due findings and heater systems in buildings. interest in oilfuel burner technology is re-emerging to theand increase different to obtain the combustion andfuels, emission of of fuel pricesmethods and theused needbytoresearchers utilize waste oils, expand renewable andcharacteristics provide operational biodiesel, study on the utilization of CME biodiesel can be done extensively using an industrial oil assurance against curtailments and fuel shortages. Despite the different findings and different methods
used by researchers to obtain the combustion and emission characteristics of biodiesel, study on the utilization of CME biodiesel can be done extensively using an industrial oil burner rather than a
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diesel engine, as reported by other researchers. In this paper, the combustion and emission from the Energies 2017, 10, 458 4 of 11 utilization of CME biodiesel at low blend ratios of B5, B15, and B25 were investigated as a preliminary evaluation of rather the suitability of engine, applying this fuelbyinother an oil burner at to air conditions. burner than a diesel as reported researchers. In different this paper,fuel the combustion The combustor wallfrom temperatures andofexhaust emission concentrations burning these biodiesel and emission the utilization CME biodiesel at low blend ratios offrom B5, B15, and B25 were investigated as a preliminary evaluation blends were compared with that of CDF. of the suitability of applying this fuel in an oil burner at different fuel to air conditions. The combustor wall temperatures and exhaust emission concentrations from burning these biodiesel blends were compared with that of CDF. 2. Methodology
CME biodiesel was produced at the Combustion Laboratory, Faculty of Mechanical Engineering, 2. Methodology Universiti Teknologi Malaysia usingat conventional laboratoryFaculty apparatus. The transesterification CME biodiesel was produced the Combustion Laboratory, of Mechanical Engineering, processUniversiti of coconut oil produces Coconut Methyl laboratory Ester (CME). There three stages in the Teknologi Malaysia using conventional apparatus. Theare transesterification process of coconut oilwhich produces Coconut Ester (CME). Therethe aretransesterification three stages in theprocess, transesterification process, includes theMethyl pre-treatment process, ◦ C at 400 rpm transesterification process, which includes the pre-treatment process, the transesterification and the post-treatment process. In the pre-treatment process, coconut oil was heated at 60process, and the post-treatment process. In the pre-treatment process, coconut oil was heated at 60 °C at 400 rpm for 1 h using a rotary evaporator to remove any moisture from the feedstock. Then the coconut oil was for 1 h using a rotary evaporator to remove any moisture from the feedstock. Then the coconut oil mixed with 25% by volume of methanol (MeOH) and 1% by weight of Potassium Hydroxide (KOH) to was mixed with 25% by volume of methanol (MeOH) and 1% by weight of Potassium Hydroxide ◦ C and 400 rpm stirring speed. In the produce(KOH) CME to and glycerol inand lessglycerol than 2 in h less of reaction at 60 time produce CME than 2 h time of reaction at 60 °C and 400 rpm stirring post-treatment the glycerol formed at the bottom removed and the CME speed. Inprocess, the post-treatment process, the glycerol formed layer at the was bottom layer was removed andunderwent the ◦ CME underwent the cleaning process, with distilled water being heated at 50 °C at various intervals the cleaning process, with distilled water being heated at 50 C at various intervals to remove any to remove any unwanted impurities and remaining glycerol. the CME fora rotary unwanted impurities and remaining glycerol. Finally, the CME Finally, was reheated forwas 30 reheated min using 30 min using a rotary evaporator to remove any remaining water. The final product is a refined CME evaporator to remove any remaining water. The final product is a refined CME as shown in Figure 2. as shown in Figure 2.
Figure 2. Refined Coconut Methyl Ester (CME).
Figure 2. Refined Coconut Methyl Ester (CME). 2.1. Fuel Blends and Physical Properties
2.1. Fuel Blends Properties CMEand wasPhysical mixed with CDF to produce B5, B15, and B25 biodiesel blends. A sample of each fuel blend was taken to test its physical properties in terms of density at 15 °C, kinematic viscosity at CME was mixed with CDF to produce B5, B15, and B25 biodiesel blends. A sample of each 40 °C, surface tension at 15 °C, and gross calorific value. The testing was conducted at the Chemical fuel blend was taken to test its physical properties in terms of density at 15 ◦ C, kinematic viscosity Engineering Laboratory, Faculty of Chemical Engineering and Petroleum Engineering, Universiti ◦ C, and gross calorific value. The testing was conducted at the Chemical at 40 ◦ C,Teknologi surface tension 15 volume Malaysia.atThe and properties of diesel, CME, and their blends (B5, B15, and B25) Engineering Laboratory, are given in Table 1. Faculty of Chemical Engineering and Petroleum Engineering, Universiti Teknologi Malaysia. The volume and properties of diesel, CME, and their blends (B5, B15, and B25) Table 1. The fuel properties of Conventional Diesel Fuel and CME biodiesel blends. are given in Table 1. Properties
Standard
Fuels
Unit
CDFFuel B5 B15biodiesel B25 blends. B100 Table 1. The fuel properties of Conventional Diesel and CME
CME Volume L Diesel Volume L Density at 15 °C ASTM D941 Unit kg/m3 Properties Standard Kinematic Viscosity at 40 °C ASTM D445 mm2/s Surface Tension at 15 °C ASTM D971 N/m CME Volume L Gross Calorific Value ASTM D240 kJ/kg Diesel Volume L Density at 15 ◦ C ASTM D941 kg/m3 Kinematic Viscosity at 40 ◦ C ASTM D445 mm2 /s Surface Tension at 15 ◦ C ASTM D971 N/m Gross Calorific Value ASTM D240 kJ/kg
0 10 830.1 CDF 3.5018 0.0295 0 45,290 10
830.1 3.5018 0.0295 45,290
0.5 1.5 9.5 8.5 Fuels 831.5 834.3 B5 3.3600 B15 3.4678 0.0296 0.5 0.0296 1.5 44,734 9.5 43,891 8.5
831.5 3.4678 0.0296 44,734
834.3 3.3600 0.0296 43,891
2.5 7.5 837.1 858.2 B25 2.8396B100 3.2594 0.0297 2.5 0.0305 43,136 7.5 37,654 -
837.1 3.2594 0.0297 43,136
858.2 2.8396 0.0305 37,654
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2.2. Experimental Set-Up 2.2. Experimental Set-Up Figure 3 shows the schematics of the experimental set-up for the combustion test. The set up Figure shows theGrade schematics of the experimental set-upspray for the combustion test. The set up included the3Industrial Light Oil Burner with a standard nozzle, a type-K thermocouple included the Industrial Grade Light Oil Burner with a standard spray nozzle, a type-K thermocouple with a maximum temperature of 1200 °C, a 1000 mm length open-ended mild steel combustion ◦ with a maximum of 1200 a 1000 mmdata length open-ended mildairsteel combustion chamber insulated temperature by cast cement, a MidiC, temperature logger, an LCA 6000 speed indicator, chamber insulated by cast cement, a Midi temperature data logger, an LCA 6000 air speed indicator, and a Horiba Enda 5000 gas analyzer. The burner was fixed at the front inlet of the combustion and a Horiba Enda 5000 gas analyzer. The burner was fixed at the front inlet of the combustion chamber to blow air and ignite the fuel. Eight thermocouples were placed along the wall of the top chamber to blow air and ignitechamber; the fuel. Eight placed along of the 100 wall mm. of the The top surface of the combustion each thermocouples separated at were an equidistance surface of the combustion chamber; each separated at an equidistance of 100 mm. The thermocouples thermocouples were connected to the Midi temperature data logger, which transformed the electric were to the Midi temperature data logger, whichalong transformed the electric signalwall. fromThe the signalconnected from the thermocouples to the temperature values the combustion chamber thermocouples to the temperature along combustion chamber wall. The Steinen standard Steinen standard nozzle was fixedvalues to spray thethe fuel into the combustion chamber. For the spray nozzle was fixed to spray the fuel into the combustion chamber. For the spray nozzle, a single orifice nozzle, a single orifice nozzle that produces a finely atomized solid cone spray distribution pattern nozzle that of produces finelyThis atomized cone distribution an angle of 5.68 45◦ was at an angle 45° wasaused. nozzle solid sprays fuelspray at a pressure of 6.8pattern bar at aatflow rate of L/h, used. This in nozzle sprays fuelAn at aemission pressure chamber of 6.8 bar was at a flow rate of 5.68 L/h, as shown in Figure 4 [24]. as shown Figure 4 [24]. connected to the exhaust of the combustion An emission wasemission connectedfrom to thethe exhaust of the combustion chamber to channel emission chamber to chamber channel the combustion to the emission sensors. The the sensor then from the combustion to the emission sensors. The sensor then sends an electrical signal to the Horiba sends an electrical signal to the Horiba Enda 5000 to display NOx, SO2, and CO emission levels. An Enda 5000indicator to displaywas NOused CO appropriate emission levels. An air indicator was usedfor to set x , SOto 2 , and air speed set the air flow to speed fuel flow mixture ratios all the the appropriate air flow to fuel flow mixture ratios for all the different equivalence ratios. different equivalence ratios. The An equivalence equivalence ratio ratio lower lower The equivalence equivalence ratios ratios used used in in this this experiment experiment were were 0.8, 0.8, 1.0, 1.0, and and 1.2. 1.2. An than stoichiometry 1.0 (Φ < 1.0) is a lean mixture having more air and less fuel, while above than stoichiometry 1.0 (Ф < 1.0) is a lean mixture having more air and less fuel, while above 1.0 1.0 (Φ > 1.0) is a rich mixture having less air and more fuel. (Ф > 1.0) is a rich mixture having less air and more fuel.
(a)
(b) Figure apparatus set set up; up; (b) (b) Combustion Combustion set set up up photo. photo. Figure 3. 3. (a) (a) Schematic Schematic diagram diagram of of combustion combustion apparatus
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Figure 4. Industrial standard nozzle spray. Figure 4. Industrial standard nozzle spray.
3. Results and Discussion 3. Results and Discussion The experimental results for the combustion test include fuel physical properties, wall The experimental results for the combustion test include fuel physical properties, wall temperature temperature profiles, and gaseous emissions. The wall temperature was based on the temperature profiles, and gaseous emissions. The wall temperature was based on the temperature detected by detected by thermocouples along the combustion chamber wall and plotted against the thermocouple thermocouples along the combustion chamber wall and plotted against the thermocouple distance distance from the burner entrance to the combustion chamber. The gaseous emission concentrations from the burner entrance to the combustion chamber. The gaseous emission concentrations for NOx , for NOx, SO2, and CO are plotted against the equivalence ratios for all the fuels tested. SO2 , and CO are plotted against the equivalence ratios for all the fuels tested. 3.1. Fuel Properties 3.1. Fuel Properties The increase of CME content inside the blends with CDF increases the density and surface The increase of CME content inside the blends with CDF increases the density and surface tension tension of the biodiesel blends but reduces the kinematic viscosity and calorific value of the fuels, as of the biodiesel blends but reduces the kinematic viscosity and calorific value of the fuels, as shown shown in Table 1. The increase in density is related to the high content of saturated fatty acid in in Table 1. The increase in density is related to the high content of saturated fatty acid in coconut coconut oil. Lauric acid and mystric acid are saturated fatty acid that make up the majority oil. Lauric acid and mystric acid are saturated fatty acid that make up the majority composition of composition of the coconut oil. It has a single bond between its carbon chain atoms and hydrogen the coconut oil. It has a single bond between its carbon chain atoms and hydrogen atoms. Such a atoms. Such a configuration allows more hydrogen atoms to bond with carbon chain atoms and configuration allows more hydrogen atoms to bond with carbon chain atoms and makes it heavier and makes it heavier and denser than unsaturated fatty acid [25]. Thus, the increase of CME content denser than unsaturated fatty acid [25]. Thus, the increase of CME content contributes to the increase contributes to the increase in biodiesel density. The increase of CME biodiesel surface tension is due in biodiesel density. The increase of CME biodiesel surface tension is due to the presence of alkyl ester to the presence of alkyl ester in biodiesel blends. It increases the intermolecular forces between fuel in biodiesel blends. It increases the intermolecular forces between fuel molecules, strengthening the molecules, strengthening the weak intermolecular forces between hydrocarbon chains in diesel fuel [26]. weak intermolecular forces between hydrocarbon chains in diesel fuel [26]. Lower viscosity of CME Lower viscosity of CME biodiesel blends is related to the fuel carbon size and chain length of fatty biodiesel blends is related to the fuel carbon size and chain length of fatty acid, as explained in [27,28]. acid, as explained in [27,28]. A long chain fatty acid leads to a bigger carbon size and also longer A long chain fatty acid leads to a bigger carbon size and also longer carbon chains (14 and above), carbon chains (14 and above), which will increase fuel viscosity. The coconut oil composition is which will increase fuel viscosity. The coconut oil composition is primarily made up of medium-chain primarily made up of medium-chain fatty acid (MCFA), which has around 6 to 12 carbon atoms in a fatty acid (MCFA), which has around 6 to 12 carbon atoms in a single chain. This reduces the viscosity single chain. This reduces the viscosity of CME biodiesel. The calorific value of CME biodiesel was of CME biodiesel. The calorific value of CME biodiesel was reduced due to the high oxygen content in reduced due to the high oxygen content in biodiesel [29]. It improves the cetane number (an biodiesel [29]. It improves the cetane number (an indication of combustion speed) of the fuel blend by indication of combustion speed) of the fuel blend by reducing the ignition delay period and reducing the ignition delay period and enhances faster fuel vaporization; thus combustion can take enhances faster fuel vaporization; thus combustion can take place at a lower temperature with low place at a lower temperature with low NOx formation [21]. NOx formation [21]. 3.2. Wall Temperature Profile 3.2. Wall Temperature Profile The fuel to air equivalence ratio affects the wall temperature profile for all CME biodiesel The fuel to air equivalence ratio affects the wall temperature forand all then CMEtobiodiesel blends during combustion. By increasing the equivalence ratio from profile 0.8 to 1.0 1.2, the blends during combustion. By increasing the equivalence ratio from 0.8 to 1.0 and then to 1.2,fuel the combustion condition changed from a lean fuel mixture to stoichiometry and finally to a rich combustion condition changed from a lean fuel mixture to stoichiometry and finally to a rich fuel mixture. Consequently, the volume of air flow decreased as the fuel flow rate increased. In all of the mixture. Consequently, the volume of the air flow decreased as the fuel(Φ flow rateproduced increased. In all ofwall the tested fuels (CME blends and diesel), higher equivalence ratio = 1.2) a higher tested fuels (CME andof diesel), theofhigher equivalence ratio (Φ = 1.2) produced a higher temperature profileblends regardless the type fuel being used. This is because more fuel is burned atwall fuel temperature profile regardless of the type of fuel being used. This is because more fuel is burned at rich mixture conditions, and consequently more heat is released during combustion [30]. Therefore, fuel rich mixture conditions, and consequently more heat is released during combustion [30]. Therefore, the overall temperature profile pattern for each fuel and its equivalence ratio is similar to each other as shown in Figure 5.
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the overall temperature profile pattern for each fuel and its equivalence ratio is similar to each other as Energies 10, 458 5. shown2017, in Figure
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(a)
(b)
(c) Figure 5. The temperature profile for all fuels at different equivalence ratios, (a) lean fuel mixture; Figure 5. The temperature profile for all fuels at different equivalence ratios, (a) lean fuel mixture; (b) stoichiometry; (c) rich fuel mixture. (b) stoichiometry; (c) rich fuel mixture.
The temperature profile begins with the increase of the wall temperature at a distance of 100 mm temperature profileinlet. begins with the increase of the wallistemperature at length a distance of 100 to 500The mm from the burner The highest wall temperature at a chamber of 600 mmmm for to 500 mm from the burner inlet. The highest wall temperature is at a chamber length of 600 mm for all blends at all equivalence ratios. It is the point at where air and fuel are homogeneously all blends at all equivalence ratios. It is the point at where air and fuel are homogeneously combusted combusted together to produce a higher amount of heat energy [30], thus indicating the size of the together to produce a higher amount then of heat energy [30], thus indicating formed. flame formed. The wall temperature begins to drop at 700 mm untilthe thesize endofofthe theflame combustion The wall temperature begins to drop at 700 mmisuntil the end the combustion (800 mm), chamber (800 mm), then indicating that the flame nearing itsoftip. Diesel has chamber the highest wall temperature for each equivalence ratio followed by CME B5, CME B15, and CME B25. At stoichiometric conditions, the combustion of CDF produced a maximum wall temperature of 847.0 °C, followed by CME B5 at 810.5 °C, CME B15 at 786.3 °C, and CME B25 at 770.0 °C. The reduction in the highest wall temperature as compared to CDF for CME B5 is 4.31%, followed by
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indicating that the flame is nearing its tip. Diesel has the highest wall temperature for each equivalence ratio followed by CME B5, CME B15, and CME B25. At stoichiometric conditions, the combustion of Energies 2017, 10, 458 8 of 11 CDF produced a maximum wall temperature of 847.0 ◦ C, followed by CME B5 at 810.5 ◦ C, CME B15 at ◦ C. The reduction in the highest wall temperature as compared to CDF 786.3 ◦B15 C, and CME B25 770.0B25 CME at 7.17% and at CME at 9.09%. These peak temperatures occur at the middle section of for CME B5 is 4.31%, followed by CME B15 at 7.17% and CMEThe B25increase at 9.09%.ofThese temperatures the combustor due to the high heat intensity at this point. CMEpeak content in diesel occur atreduces the middle section of the combustor the high heat intensity this point. The increase blends the calorific value of biodieseldue fueltoblends, causing the wallattemperature to be lower of CME content in diesel blends reduces the calorific value of biodiesel fuel blends, causing the wall than that of CDF. temperature to be lower than that of CDF.
3.3. Gaseous Emission 3.3. Gaseous Emission Gaseous emissions such as NOx, SO2, and CO are toxic emissions that are harmful to the Gaseous emissions such as NOx , SO , and CO are toxic emissions that are harmful to the environment and human health at high 2concentrations. Hence, it is important to identify the environment and human health at high concentrations. Hence, it is important to identify the emissions emissions from the combustion of coconut oil-based biodiesel blend to determine its suitability as a from the combustion of coconut oil-based biodiesel blend to determine its suitability as a replacement replacement for fossil fuels. This section provides the comparison of emission concentrations for for fossil fuels. This section provides the comparison of emission concentrations for CME blends with CME blends with CDF at all equivalence ratios. CDF at all equivalence ratios. 3.3.1. 3.3.1. NO NOxxEmission Emission The concentration The concentration of of NO NOxx emission emission for for each each fuel fuel tested tested (CDF (CDF and and CME CME blends) blends) at at different different equivalence ratios are shown in Figure 6. The graphs showed that diesel and CME blends exhibit the equivalence ratios are shown in Figure 6. The graphs showed that diesel and CME blends exhibit same NO x trend. At stoichiometric conditions, CDF emits the highest NOx emission of 61 ppm, the same NOx trend. At stoichiometric conditions, CDF emits the highest NOx emission of 61 ppm, followed by CME CMEB5 B5atat58 58ppm, ppm,CME CMEB15 B15 ppm, and CME at ppm. 50 ppm. Figure 6 also shows followed by atat 5151 ppm, and CME B25B25 at 50 Figure 6 also shows that, that, the region lean region (Φincreasing < 1), increasing the equivalence ratio increases NOx emission, which in theinlean (Φ < 1), the equivalence ratio increases the NOthe x emission, which reaches reaches peak at the equivalence ratio (Φ =then 1) and then decreases in the rich(Φ region 1). peak value atvalue the equivalence ratio of 1.0 (Φof= 1.0 1) and decreases in the rich region > 1). (Φ At>fuel At fuel lean mixtures, NOx increases due to thermal effect the increasing temperature, and the lean mixtures, NOx increases due to thermal effect from thefrom increasing temperature, and the presence presence of excess oxygen allows the oxidation of nitrogen in the atmosphere to form of excess oxygen allows the oxidation of nitrogen in the atmosphere to form NO, contributing toNO, the contributing to the formation ofofNO x. The increase of NO from the thermal effect continues until it formation of NO . The increase NO from the thermal effect continues until it reaches stoichiometric x reaches stoichiometric In the richof mixture, the thus content of air isthe less, thus reducing the conditions. In the fuelconditions. rich mixture, the fuel content air is less, reducing reaction of nitrogen reaction of nitrogen with oxygen to produce NO. with oxygen to produce NO.
Figure 6. The NO emission profile for CDF and different CME blends. Figure 6. The NOxx emission profile for CDF and different CME blends.
The increase CME content in diesel blendsblends reducesreduces the production of NOx during combustion. The increaseofof CME content in diesel the production of NO x during CME B5 produces CME B15 produces16.39%, and CME B25 produces lower NO combustion. CME 4.92%, B5 produces 4.92%, CME B15 produces16.39%, and CME18.03% B25 produces 18.03% x than CDF does stoichiometric The higher cetane numbers CMEnumbers shorten the ignition time lower NOxatthan CDF does atconditions. stoichiometric conditions. The higher of cetane of CME shorten during fuel spray. Moderate inside the chamberinside can restrict the reaction of nitrogen the ignition time during fueltemperatures spray. Moderate temperatures the chamber can restrict the with oxygen to formwith NOxoxygen whichto requires high temperatures to betemperatures produced. The reduction of NO reaction of nitrogen form NO x which requires high to be produced. Thex during combustion can becombustion related to fuel biodiesel is comprised of shorter reduction of NOx during canproperties. be relatedCoconut-based to fuel properties. Coconut-based biodiesel is hydrocarbon chains than conventional diesel. The medium carbon chain length will result in a lower comprised of shorter hydrocarbon chains than conventional diesel. The medium carbon chain length flame temperature and thustemperature less NO formation. will result in a lower flame and thus less NO formation.
3.3.2. SO2 Emission Figure 7 shows the SO2 emission for each tested fuel at different equivalence ratios. At stoichiometric conditions, CDF produces the highest SO2 emission of 14 ppm, followed by CME B5 at 12 ppm, CME B15 at 7 ppm, and CME B25 at 6 ppm. In the lean region (Φ < 1), by increasing the
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3.3.2. SO2 Emission Figure 7 shows the SO2 emission for each tested fuel at different equivalence ratios. 9 of 11 9 of B5 11 conditions, CDF produces the highest SO2 emission of 14 ppm, followed by CME at 12 ppm,in CME 7 ppm,(Φand CME at 6 ppm.ofInSO the lean region (Φ < 1), by increasing the decreases the B15 richatregion > 1). TheB25 formation 2 increases when the temperature and decreases in ratio, the rich region (Φ to > reach 1). The formation ofatSO 2 increases when the temperature and equivalence SO increases its peak value stoichiometric (Φ = 1) and then 2 oxygen concentrations are high [31,32]. Under the lean fuel mixture (Φ 1), the temperature is and has excess air, which increases the formation of SO 2 . At rich mixtures (Φ > 1), the temperature is concentrations are high [31,32]. Under the lean fuel mixture (Φ < 1), the temperature is high and has greater than in the lean mixture but there is less air; thus less SO2 is formed. At stoichiometric greater than in the lean mixture but there is 2less thus less SO 2>is At stoichiometric excess air, which increases the7.69%, formation SO . At air; rich mixtures (Φ 53.85% 1),formed. theless temperature is greater conditions, CME B5 produces CMEofB15 46.15%, and CME B25 SO2 than does CDF. conditions, CME B5 produces 7.69%,isCME B15thus 46.15%, and CME B25 53.85% less SO 2 than conditions, does CDF. than in the lean mixture but there less air; less SO is formed. At stoichiometric 2 CME has less sulphur content than diesel, which further reduces the formation of SO2 for all CME hasproduces less sulphur diesel, further reduces formation SO2 has for less all CME B5 7.69%,content CME B15than 46.15%, andwhich CME B25 53.85% less SO2the than does CDF.ofCME combustion conditions. combustion conditions. sulphur content than diesel, which further reduces the formation of SO2 for all combustion conditions. Energies 2017, 10, 458 Energies 2017, 10, 458 At stoichiometric
Figure 7. The SO emission profile for CDF and different CME blends. Figure 7. 7. The The SO SO222emission emissionprofile profilefor forCDF CDFand anddifferent different CME CME blends. blends. Figure
3.3.3. CO Emission 3.3.3. CO CO Emission Emission 3.3.3. Figure shows the emission of CO for CDF CDF and and CME CME blends for for each equivalence equivalence ratio. ratio. At Φ 0.8, Figure 888 shows shows the the emission emission of of CO CO for for At Φ Φ ===0.8, 0.8, Figure CDF and CME blends blends for each each equivalence ratio. At by increasing the equivalence ratio, CO emission decreases to reach its lowest value at stoichiometric by increasing the equivalence ratio, CO emission decreases to reach its lowest value at stoichiometric by increasing the equivalence ratio, CO emission decreases to reach its lowest value at stoichiometric conditions (Φ 1) and then rises rises sharply sharply in in rich conditions conditions (Φ >> 1). 1). At stoichiometric conditions conditions conditions (Φ (Φ === 1) 1) and and then then At stoichiometric stoichiometric conditions rises sharply in rich rich conditions (Φ (Φ > 1). At conditions (Φ = 1), CDF produces 21 ppm of CO emission, followed by CME B5 and B15 at 2 ppm and CME B25 (Φ ==1), 1),CDF CDFproduces produces21 21ppm ppmof ofCO COemission, emission,followed followed by by CME CME B5 B5 and and B15 B15 at at 22 ppm ppm and and CME CME B25 B25 (Φ at 1 ppm, resulting in a 90.48% reduction for CME B5 and CME B15 and a 95.24% reduction for CME at 11 ppm, ppm, resulting resulting in in aa 90.48% 90.48% reduction reduction for for CME CME B5 B5 and and CME CME B15 B15 and and aa 95.24% 95.24% reduction reduction for for CME CME at B25. CO emission concentration is highest during an incomplete combustion of fuel in aa low oxygen B25. CO emission concentration is highest during an incomplete combustion of fuel in low oxygen B25. CO emission concentration is highest during an incomplete combustion of fuel in a low oxygen environment. The fuel rich mixture conditions during combustion promote higher formation of CO environment. The The fuel fuel rich rich mixture mixture conditions conditions during during combustion combustion promote promote higher higher formation formation of of CO CO environment. due to high fuel consumption and inadequate air supply. The increasing content of CME in diesel due to to high The increasing content of CME in diesel fuel due high fuel fuel consumption consumptionand andinadequate inadequateairairsupply. supply. The increasing content of CME in diesel fuel reduces theemission CO emission significantly as biodiesel contains 10 between 10 to more 12 percent more reduces the CO significantly as biodiesel contains between to 12 percent oxygen than fuel reduces the CO emission significantly as biodiesel contains between 10 to 12 percent more oxygen than CDF [33,34]. In extra biodiesel, the extra oxygen content promotes the conversion of CO to CDF [33,34]. biodiesel, oxygen promotes the conversion CO to CO2 , resulting in oxygen than In CDF [33,34].the In biodiesel, thecontent extra oxygen content promotes of the conversion of CO to CO 2, resulting in complete combustion of the fuel. complete combustion of thecombustion fuel. CO 2, resulting in complete of the fuel.
Figure 8. The CO emission profile for CDF and different CME blends. Figure 8. The CO emission profile for CDF and different CME blends. Figure 8. The CO emission profile for CDF and different CME blends.
4. Conclusions 4. Conclusions The experiments regarding the combustion and emission characteristics of CME biodiesel The experiments regarding the combustion and emission characteristics of CME biodiesel blends in a liquid fuel burner were conducted and compared with CDF at various equivalence blends in a liquid fuel burner were conducted and compared with CDF at various equivalence ratios. Fuel properties such as density, kinematic viscosity, surface tension, and calorific value were ratios. Fuel properties such as density, kinematic viscosity, surface tension, and calorific value were
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4. Conclusions The experiments regarding the combustion and emission characteristics of CME biodiesel blends in a liquid fuel burner were conducted and compared with CDF at various equivalence ratios. Fuel properties such as density, kinematic viscosity, surface tension, and calorific value were measured for each fuel blends. Then, all fuels were combusted at different equivalence ratios to obtain the wall temperature, NOx , SO2 , and CO emission profiles. The results indicated that, by increasing the CME content in diesel blend, the density and surface tension increased while the kinematic viscosity and calorific value decreased. The chemical composition of CME altered the fuel properties of diesel, which resulted in the CME biodiesel to have different fuel properties. The chemical composition of CME also improved the fuel combustion efficiency at lower temperatures. The increase of CME content in diesel blends reduced the emissions of NOx , SO2 , and CO. The results of the study can also be concluded with the following remarks:
• • •
For all equivalence ratios, the CME biodiesel blends combust at lower temperatures than CDF. An increase in CME content reduces the combustion temperature. An increase in the fuel consumption results in a decrease in the air volume, which generates more heat energy during the combustion.
Acknowledgments: The authors would like to thank the Ministry of Higher Education of Malaysia and the Research Management Center and Innovation, Universiti Malaysia Perlis for awarding the research grant under the Fundamental Research Grant Scheme (9003-00537). The authors would also like to thank the Research Management Center and Faculty of Mechanical Engineering, Universiti Teknologi Malaysia for knowledge transfer and providing the research facilities and space to undertake this research study under grant (12J21). Author Contributions: The contributions of each authors are as follows: Muhammad Syahiran Abdul Malik and Ashrul Ishak Mohamad Shaiful provided the impetus for this work, obtained the experimental data, analyzed the numerical results and drafted the manuscript. Mohammad Nazri Mohd Jaafar, Mohd Shuisma Mohd. Ismail, and Amirah Mohamad Sahar provided insights that led to some of the distinctions between equations being highlighted and worked on rewrites and clarifications. All authors have read and approved the final manuscript. Conflicts of Interest: The authors declare no conflict of interest.
References 1.
2. 3. 4.
5.
6.
7. 8.
Puigjaner, L.; Pérez-Fortes, M.; Laínez-Aguirre, J. Towards a Carbon-Neutral Energy Sector: Opportunities and Challenges of Coordinated Bioenergy Supply Chains-A PSE Approach. Energies 2015, 8, 5613–5660. [CrossRef] Golledge, N.R.; Kowalewski, D.E.; Naish, T.R.; Levy, R.H.; Fogwill, C.J.; Gasson, E.G.W. The Multi-Millennial Antarctic Commitment to Future Sea-Level Rise. Nature 2015, 526, 421–425. [CrossRef] [PubMed] Argawal, A.; Gupta, A.K.; Pandey, A. Novel Combustion Concepts for Sustainable Energy Development; Springer: New Delhi, India, 2014. Chen, J.; Wang, W.H.; Liu, T.W.; Wu, F.H.; Zheng, H.L. Photosynthetic and Antioxidant Responses of Liquidambar Formosana and Schimasuperba Seedlings to Sulfuric-Rich and Nitric-Rich Simulated Acid Rain. Plant Physiol. Biochem. 2013, 64, 41–51. [CrossRef] [PubMed] Aslan, S.; Uzkeser, M.; Seven, B.; Gundogdu, F.; Acemoglu, H.; Aksakal, E.; Varoglu, E. The Evaluation of Myocardial Damage in 83 Young Adults with Carbon Monoxide Poisoning in the East Anatolia Region in Turkey. Hum. Exp. Toxicol. 2006, 25, 439–446. [CrossRef] [PubMed] Knothe, G.; Dunn, R.O.; Bagby, M.O. Biodiesel: The Use of Vegetable Oils and Their Derivatives as Alternative Diesel Fuels. In Fuels and Chemicals from Biomass; Saha, B.C., Woodward, J., Eds.; American Chemical Society (ACS): Washington, DC, USA, 1997; pp. 172–208. Xie, H.; Song, L.; Xie, Y.; Pi, D.; Shao, C.; Lin, Q. An Experimental Study on the Macroscopic Spray Characteristics of Biodiesel and Diesel in a Constant Volume Chamber. Energies 2015, 8, 5952–5972. [CrossRef] Ejikeme, P.M.; Anyaogu, I.D.; Ejikeme, C.L.; Nwafor, N.P.; Egbuonu, C.A.C.; Ukogu, K.; Ibemesi, J.A. Catalysis in Biodiesel production by Transesterification Processes—An Insight. J. Chem. 2010, 7, 1120–1132. [CrossRef]
Energies 2017, 10, 458
9. 10. 11.
12. 13. 14. 15. 16. 17.
18. 19.
20. 21.
22.
23. 24. 25. 26.
27. 28.
29. 30. 31. 32.
11 of 12
Magin, L.; Rodríguez-Fernández, J.; Agudelo, J.R. Diesel Particulate Emissions from Used Cooking Oil Biodiesel. Bioresour. Technol. 2008, 99, 731–740. Mustafa, C.; Van Gerpen, J.H. Comparison of Engine Performance and Emissions for Petroleum Diesel Fuel, Yellow Grease Biodiesel, and Soybean Oil Biodiesel. Trans. ASAE 2003, 46, 937. Mohd Jaafar, M.N.; Eldrainy, Y.A.; Mat Ali, M.F.; Wan Omar, W.Z.; MohdHizam, M.F.A. Combustion Performance Evaluation of Air Staging of Palm Oil Blends. Environ. Sci. Technol. 2012, 46, 2445–2450. [CrossRef] [PubMed] Ja’afar, M.N.M.; Omar, W.Z.W.; Rahim, M.R.; Azmi, I.; Abdullah, M.H. Study on Combustion Performance of Palm Oil Biodiesel Blend. J. Teknol. 2014, 69, 127–131. Ganjehkaviri, A.; Jaafar, M.N.M.; Hosseini, S.E.; Musthafa, A.B. Performance Evaluation of Palm Oil-Based Biodiesel Combustion in an Oil Burner. Energies 2016, 9, 97. [CrossRef] Raghavan, K. Biofuels from Coconuts; Fuels from Agriculture in Communal Technology (FACT) Foundation: Wageningen, The Netherlands, 2010. Price Policy for the 2016 Season Copra. Commission for Agricultural Costs and Prices; Ministry of Agriculture of India: New Delhi, India, 2015. Cloin, J. Coconut Oil as a Biofuel in Pacific Islands: Challenges and Opportunities; South Pacific Applied Geoscience Commission: Suva, Fiji, 2005. Saifuddin, N.; Fazlili, A.; Kumaran, P.; Pei-Jua, N.; Priathashini, P. The Production of Biodiesel and Bio-kerosene from Coconut Oil Using Microwave Assisted Reaction. Earth Environ. Sci. 2016, 32, 12039–12043. [CrossRef] Suryanto, A.; Suprapto, S.; Mahfud, M. The Production of Biofuels from Coconut Oil Using Microwave. Modern Appl. Sci. 2015, 9, 93. [CrossRef] Llamas, A.; García-Martínez, M.J.; Al-Lal, A.M.; Canoira, L.; Lapuerta, M. Biokerosene from Coconut and Palm Kernel Oils: Production and Properties of Their Blends with Fossil Kerosene. Fuel 2012, 102, 483–490. [CrossRef] Giles, V. Pacific Regional Workshop on Biofuels: Opportunities and Implications for Sustainable Livelihoods in Pacific Island Countries; Pacific Regional Workshop: Nadi, Fiji, 2008. Liaquat, A.M.; Masjuki, H.H.; Kalam, M.A.; Fattah, I.R.M.; Hazrat, M.A.; Varman, M.; Mofijur, M.; Shahabuddin, M. Effect of Coconut Biodiesel Blended Fuels on Engine Performance and Emission Characteristics. Procedia Eng. 2013, 56, 583–590. [CrossRef] Woo, C.; Kook, S.; Hawkers, E.; Rogers, P.L.; Marquis, C. Engine Combustion and Emission of Coconut Oil Based Biodiesel and Diesel Blends. In Proceedings of the 19th Australasian Fluid Mechanics Conference, Melbourne, Australia, 8–11 September 2014. Salleh, M.M.N. Study on the Performance of Envo Diesel in a Combustion System. Master’s Thesis, Universiti Teknologi Malaysia, Skudai, Malaysia, 2015. Steinen Nozzle Catalog. Industrial Mining Oil Burner; Steinen Mfg. Co.: Parsippany, NJ, USA, 2016. Myers, R.L. The Basics of Chemistry, 1st ed.; Greenwood Pub Group: Santa Barbara, CA, USA, 2003. Ramalho, E.F.S.M.; Filho, J.R.C.; Albuquerque, A.R.; de Oliveira, S.F.; Cavalcanti, E.H.S.; Stragevitch, L.; Santos, I.M.G.; Souza, A.G. Low Temperature Behavior of Poultry Fat Biodiesel: Diesel Blends. Fuel 2012, 93, 601–605. [CrossRef] Refaat, A.A. Correlation between the Chemical Structure of Biodiesel and Its Physical Properties. Int. J. Environ. Sci. Technol. 2009, 6, 677–694. [CrossRef] Puhan, S.; Saravanan, N.; Nagarajan, G.; Vedaraman, N. Effect of Biodiesel Unsaturated Fatty Acid on Combustion Characteristics of a DI Compression Ignition Engine. Biomass Bioenergy 2016, 34, 1079–1088. [CrossRef] Sivaramakrishnan, K. Determination of Higher Heating Value of Biodiesels. Int. J. Eng. Sci. Technol. 2011, 3, 7981–7987. Musthafa, A.B. Study on the Performance of Palm Methyl Ester in a Combustion System. Master’s Thesis, Universiti Teknologi Malaysia, Skudai, Malaysia, 2015. Croiset, E.; Thambimuthu, K.V. NO and SO Emissions from O/CO Recycle Coal Combustion. Fuel 2016, 80, 2117–2121. [CrossRef] Hasenberg, L.; Bender, R. Corrosion Handbook: Corrosive Agents and Their Interaction with Materials: V. 10: Sulfur Dioxide, Sodium Sulfate; Wiley-VCH Verlag GmbH: Weinheim, Germany, 2008.
Energies 2017, 10, 458
33.
34.
12 of 12
Gumus, M.; Kasifoglu, S. Performance and Emission Evaluation of a Compression Ignition Engine Using a Biodiesel (Apricot Seed Kernel Oil Methyl Ester) and Its Blends with Diesel Fuel. Biomass Bioenergy 2010, 34, 134–139. [CrossRef] Habibullah, M.; Rizwanul Fattah, I.M.; Masjuki, H.H.; Kalam, M.A. Effects of Palm–Coconut Biodiesel Blends on the Performance and Emission of a Single-Cylinder Diesel Engine. Energy Fuels 2015, 29, 734–743. [CrossRef] © 2017 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
