Effect of Rubber Seed Oil and Palm Oil Biodiesel Diesel Blends on Diesel Engine Emission and Combustion Characteristics Ibrahim Khalil 1, a, A.Rashid A.Aziz 2,b and Suzana Yusuf 3,c 1,2 Mechanical Engineering Department, Universiti Teknologi PETRONAS,Tronoh 31750, Malaysia 3 Chemical Engineering Department, Universiti Teknologi PETRONAS,Tronoh 31750, Malaysia a himakh80@gmail.com, b rashid@petronas.com.my, c drsuzana_yusuf@petronas.com.my Keywords: Crude rubber seed oil; Crude palm oil; Biodiesel; Performance, Emissions, Combustions. Abstract. Diesel engine emission has been considered as major air pollution sources. Feedstocks blending method is motivated by cost reduction and property enhancement. In this paper crude rubber seed oil and palm oil are mixed in 50:50 vol. % and converted to biodiesel. Thermophysical property of the biodiesel was studied. Blends with varying contents of diesel and biodiesel 5-20 vol. % were prepared. Engine emissions and combustion characteristics were measured and analysed. The CO emission was reduced but the exhaust gas temperature and NOx emission increased proportional to the blends ratio. Premixed combustion phase in all tested blends start earlier the neat diesel.short ignition delay and lower heat release rate were noticed. Introduction Clean fuel is crucial to improve the urban environmental conditions practically in dense populated area. Fossil fuels are the major sources of energy. Due to urbanization and industrialization the consumption of the fossil fuels increased while the production decreased. Pollutants such as CO, CO2, NOx, and many volatile organic matters emitted from burning of fossil fuel reduced the air quality around the world. Therefore, alternative energy sources are the most attractive options for fossil fuel replacement. Biodiesel is a liquid fuel produced from different types of feedstocks such as vegetable oil either edible or non-edible oil, animal fats and algae [1]. Biodiesel production from the refined edible oil is not feasible due to food threats and high production cost. Therefore, nonedible vegetable oil has a potential to overcome the problems of food threat and to reduce the production cost [2].Vegetable oil can be directly used in the diesel engine like Rudolf Diesel that used the Peanut oil for a first time as the fuel. Consequently, due to high viscosity, incomplete combustion, deposition of particulate matters and lower volatility it cannot work properly like diesel fuel. Therefore, different types of techniques were applied on the vegetable oil to overcome the high viscosity, low volatility, incomplete combustion problem which includes pyrolysis [3] microemulsion [4] and transesterification [5]. Ramadhas et al [6] studied the characterization and the effect of using rubber seed oil as fuel in a single cylinder diesel engine. It is observed that 50-80 vol. % blends give better combustion performance. Raheman et al [7] studied performance and emission on DI single cylinder diesel engine using biodiesel blends of B10 and B20 obtained from a mixture of mahua and simarouba oils at 50:50 vol.% blends ratio with high speed diesel. The result indicated that brake specific fuel consumption (BSFC) and NOx increased while brake thermal efficiency (BTE), CO and total hydrocarbon (THC) decreased. Based on the findings of various researchers, biodiesel characteristics, engine emissions and combustion characteristics are important for optimization and utilization. Hence, its application in society will reduce the dependent on fossil fuel. However, work on the combination of crude rubber seed oil and palm oil as the feedstock has not been studied and the thermophysical properties that could eventually give difference on the engine emission and combustion characteristics is lacking. Thus, an experimental investigation was conducted to study engine emissions and combustion characteristics of obtained biodiesel at 50:50 ratio of crude rubber seed oil and crude palm oil (RSPO) of Malaysian origin as supplement to the
neat diesel in blends proportions of B5, B10 and B20 in a fully instrumented four- cylinder natural aspirated, water cooled, indirect injection diesel engine. Material and Methods The crude rubber seed oil was purchased through Kinetics chemicals (M) Sdn. Bhd, the crude palm oil was purchased from Felcra Chemicals (M) while the fossil diesel was obtained from a local fuel station. All the reagents and chemical were analytical grade and purchased from Sigma Aldrich Malaysia. Biodiesel Production Crude rubber seed oil and palm oil were mixed homogenously, added to a hydrodynamic cavitation reactor and heated up to 60 C. When the temperature of the feedstock reached 60 C, the mixture of catalyst and methanol was added. In this study 1:8 oil to methanol ratio and KOH catalyst of 1% by weight of the oil and reaction time of 2 hours were used. After two hours the reaction was stopped and the sample was left for gravitational separation of glycerol and biodiesel. After six hour, two layers were obtained, upper layer contained methyl ester and the lower layer contained glycerol. The obtained product was washed with the warm de-ionized water stored for fuel properties characterization. The blending with neat diesel was performed using high speed mechanical stirrer. Characterization of Fuel Properties The density of the biodiesel and the blends were analysed using the Anton Paar DMA 4500M Density Meter. Viscosity of the biodiesel and blends were measured using Anton Paar, Lovis 2000 M/ME apparatus. The low temperature properties such as cloud point referred to ASTM D 2500 and pour point referred to ASTM D 97 were measured by using the CPP 5G s analyzer. Cold filter plugging point was measured by using the FPP 5G s analyzer. Oxidation stability was measured by using the 873-CH-9101 Metrohm analyzer. Table1 shows the properties of the synthesized biodiesel. Table 1. Biodiesel fuel properties Property Methods RSPOB ASTM D 6751 Density at 25 C kg/m3 ASTM D 4052 874 N/A Viscosity at mm2/s, 40 C ASTM 445 4.9 1.9-6.0 Calorific value (MJ/kg) 38.4 - Cetane Number ASTM D 613 50.19 47 min Oxidation stability (h) EN14112 3.77 3 min Flash Point ( C) ASTM D 93 150 93 min Cloud Point ( C) ASTM D 2500 1 - Pour Point ( C) ASTM D 97 6.5 - ColdPlugging Point ( C) ASTM D 6371 3.8 - Moisture content (%) ASTM D 2709 0.02 0.05 max Ester Content (%) EN 14103 98.113 N/A Engine Test Procedure The XLD 418D with bore of 82.5 mm, stroke of 82 mm, compression ratio of 21.5:1, torque of 110 Nm at 2500 rpm, power output of 44 kw at 4800 rpm, 4 strokes, natural aspirated, indirect injection (IDI) diesel engine was used for the present investigation as shown in Fig.1. The engine and dynamometer were controlled by a control panel equipped with data acquisition, logging and sensors. The sensors measured the engine speed, torque, power, lubrication oil pressure and temperature, air flow, coolant inlet and outlet temperature, fuel pressure and temperature, inlet air temperature and fuel consumption. A glow plug pressure transducer (Kistler model 6058A, piezostar) was installed in the engine first cylinder to measure the change in the pressure. A 250 cycle pressure data were collected with resolution of 0.25º crank angle. The data cycles were
averaged using computer program in order to eliminate variation from cycle to cycle. To measure the concentrations of exhaust gases such as carbon monoxide (CO), nitrogen oxide (NOx) and outlet gas temperature vario plus industrial exhaust gas analyzer(model 944008) was used. The experiments were conducted in a series of operational condition in full load, at variable engine speeds from 1000 to 4500 rpm. During the experiment the engine was allowed to warm up for about 15 minutes. Engine oil and coolant water temperatures were constant at 80 C. For every fuel change, fuel lines were cleaned by flushing with neat diesel and the gas analyser was calibrated accordingly. Fig. 1. Schematic diagram of engine testing. 1. Diesel tank, 2. Biodiesel tank 3. Fuel flow meter, 4. Engine exhaust, 5. Engine, 6. Eddy current dynamometer, 7. Angle encoder, 8. Pressure transducer, 9. Engine ECU control unit, 10. Engine PC control unit, 11. Signal amplifier, 12. Data acquisition unit, 13. Computer, 14. Control valve, 15. Gas analyzer unit. Results and Discussion Carbon Monoxide Emission The CO concentration in the exhaust gas is an indicator of incomplete combustion as shown in Fig.2. It is clear that the CO trend tends to decrease as the speed and biodiesel ratio increased in all cases. It is observed that, the CO emitted by biodiesel blends is lower compared pure diesel. The possible reason is the presence of oxygen content that enhanced the combustion [8]. Nitrogen Oxide Emission The nitrogen oxide emissions that being emitted from the engine s as a function of speed is presented in Fig.3. It is observed that the NOx emissions emitted by biodiesel blends are slightly higher than that of diesel. Due to lower heating value of biodiesel and increase of air/fuel near stoichiometric condition, resulting in higher temperature and higher NOx [9]. Fig.2. Carbon monoxide vs. engine speed for the fuels. Fig.3. Nitrogen oxides emission vs. engine speed for the fuels.
Exhaust Gas Temperature The exhaust gas temperature indicates the effective use of the heat energy of a fuel and it is shown in Fig.4. It is observed that the exhaust gas temperature for all biodiesel blends are higher than that of diesel due to oxygen content of biodiesel which provide better combustion [10].Generally it was noticed that no remarkable difference has been observed in exhaust temperature of blends compared to neat diesel over the inter engine speed range. Peak Cylinder Pressure The variation of maximum pressure as a function of engine s speed is shown in Fig.5. The peak cylinder pressure in all biodiesel blends were lower compared to that of diesel. Therefore, no effect on engine durability, partial burn and knocking problem were observed. The highest cylinder pressures achieved were at 3500 rpm 71. 784, 61.21, 68.04 and 67.114 bar for diesel, B5, B10 and B20 respectively. At rated engine speed of 2500 rpm, the cylinder pressure were 62.80, 65.38, 65.53 and 65.71 bar for B5, B10, B20 and neat diesel respectively as represented in Fig.6. It is clear that the pressure increased by increasing the blend ratio due to oxygen fortification which result in complete combustion. Fig.4. Exhaust gas temperature vs. engine speed for neat diesel and biodiesel blend. Fig.5. Peak cylinder pressure vs. engine speed for diesel and biodiesel blends. Heat Release Rate The heat release is defined as the rate at which work is done plus internal energy change. Heat release rate at variance crank angle is shown in Fig.7. It is noticed that, the heat release rate initially followed a downward trend, corresponding to the end of compression stroke that suddenly changes slope at initial combustion point. It is clear that the biodiesel blends completed the premixed combustion phase earlier than neat diesel due to their earlier start of combustion and having less premixed combustion. Another reason the evaporation of biodiesel is slow than neat diesel and contributed less to premixed combustion. Fig.6. Cylinder pressure vs. engine speed for the fuels at 2500 rpm. Fig.7. Heat release rate vs. crank angle at 2500 rpm for diesel and biodiesel blend.
Conclusion Characterization and engine emission and combustion characteristics of an IDI diesel engine fueled with biodiesel from a mixture of crude rubber seed oil and crude palm oil diesel blends have been investigated and compared with that of neat diesel at various engine speeds and blends ratio at full load condition. The experimental results confirmed that CO, NOx, exhaust gas temperature, peak cylinder pressure and heat release rate are a function of biodiesel blends, engine speed and load. Generally, the following conclusions can be drawn from this study. 1. All tested biodiesel blends burned easily in IDI engine. 2. CO emission found to be decrease as biodiesel concentration increases. 3. NOx and exhaust gas temperature were increased proportionally to the blends ratio. 4. All biodiesel blends completed the premixed combustion phase earlier than neat diesel due to earlier start of combustion. References [1] J.V. Gerpen, Biodiesel processing and production, Fuel Processing Technology. 86 (2005) 1097-1107. [2] F. Ma, M. A. Hanna, Biodiesel production review, Bioresource Technology.70 (1999)1-15. [3] K.Pramanik, Properties and use of jatropha curcas oil and diesel fuel blends in compression ignition engine, Renewable Energy 28 (2003)239-248. [4] A.Srivastava, R. Prasad,Triglycerides-based diesel fuels, Renw. And Sust. Enrg. Reviews. 4(2000)111-133. [5] A. Junaid, S. Yusuf, A. Bokhari, R.N. Kamil, Study of fuel properties of rubber seed oil based biodiesel, Energy Conversion and Management.78(2014), 266-275. [6] A.S.Ramdhas,S. Jayaraj,C.Muraleedharan, Characterization and effect of using rubber seed oil as fuel in the compression ignition engines, Renewable Energy.30(2005)795-803. [7] H.Raheman, P.C. Jena, S.S.Jadav, Performance of a diesel engine with blends of biodiesel (from a mixture of oils) and high-speed diesel, International Journal of Energy and Environmental Engineering 4(2013), 1-1. [8] D.K. Bora, D.C. Baruah, Assessment of tree seed oil biodiesel: A comparative review based on biodiesel of a locally available tree seed, Renewable and Sustainable Energy Reviews. 16 (2012)1616-1629. [9] P.McCarthy, M.G.Rasul,S.Moazzem, Analysis and comparison of performance and emissions of an internal combustion engine fuelled with petroleum diesel and different bio-diesel,fuel 90(2011), 2147-2157. [10] S.A.Basha, K.R.Gopal, S.Jebaraj, A review on biodiesel production, combustion, emissions and performance. Renewable and Sustainable Energy Reviews 13 (2009), 1628-1634