INVESTIGATION OF PERFORMANCE AND EMISSION CHARACTERISTICS OF A COMPRESSION IGNITION ENGINE WITH OXYGENATED FUEL

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1 INVESTIGATION OF PERFORMANCE AND EMISSION CHARACTERISTICS OF A COMPRESSION IGNITION ENGINE WITH OXYGENATED FUEL S. B. Deshmukh 1, D. V. Patil 2, A. A. Katkar 3 and P.D. Mane 4 1,2,3 Mechanical Engineering Department, Sanjeevan Engineering & Technology Institute, Panhala 4 Mechanical Engineering Department, TKIET, Warananagar Abstract- Investigation of performance and emission characteristics is carried out on compression ignition engine using methanol as oxygenated compound in diesel fuel. Fuel formulations are performed with mixture of additives and methanol content varying from 5 to 15% in volume in relation to the diesel fuel. Performance of direct injection diesel engine with blends is compared with that of diesel fuel. The study showed that the engine thermal efficiency increases with increase in oxygen mass fraction (or methanol mass fraction). Smoke is formed in combustion chamber because of incomplete combustion of fuel. The quantity of smoke in exhaust gas can be reduced by supplying additional oxygen through these fuel blends. It showed a marked reduction in exhaust smoke without any cyclic irregularities. Further increase in the fuel injection advance angle has achieved a better engine thermal efficiency. Keywords- Emission, compression ignition engine, oxygenated fuels, methanol, smoke, engine performance & emission analysis. I. INTRODUCTION Worldwide petroleum reserves are a non-replenish able commodity. The rate of depletion depends primarily on the economic growth rates of all the countries of the world and the production rates allowed by oil producing nations. Diesel fueled engines have the major disadvantage of producing soot particles, nitrogen oxides and are now subjected to increasingly severe legislation following revision of standards. The required levels are difficult to achieve through engine design alone. Even when exploiting all the possibilities of modifying engine design and of exhaust treatment, diesel engine development will face serious difficulties when it comes to reaching the stipulated limits. Hence, the question arises as to whether fuel can render a contribution towards influencing combustion in diesel engine in such a way that the stipulated pollution emission limits can be reached. The introduction of oxygenated compounds such as alcohols into diesel fuel is all today the best way to have results in matter of pollution [1]. Wang et al. [2] and Miyamoto et al. [3] studied emissions and combustion with different oxygenated compounds and EGR. They realized that significant improvements in smoke, particulate matter, NO x, HC and thermal efficiency with oxygenates. Engine performance and emission analysis for four blends of diesel and ethanol with diesel fuel were tested by Yusuf et al. [4]. They found that emissions to be minimum, without a significant drop in engine power output. Improved exhaust gas quality from diesel engines were observed by Sperling et al. [5] when it operating on n-butanol / Diesel fuel mixtures. Micro emulsions of methanol and ethanol in diesel fuel have been successfully formulated and studied in a CLR single cylinder diesel engine by Moses et al. [6]. They evaluated their potential of extending diesel fuel supplies. Historically there had been little interest in using alcohols in compression ignition engines. The use of pure alcohol requires a very high compression ratio for ignition. Detroit Diesel Allison in Brazil reported some development work with a 23:1 CR version of 4-cylinder, series 53 engine [6]. DOI: /IJMTER IDAVY 202

2 Castor oil was added to the ethanol to provide lubricity and to act as an ignition improver. The most serious problem appears to have gum formation from the castor oil. Another way is to use the alcohol as a diesel fuel extender rather than as a primary fuel. The objective of this study is to form a stabilized diesel-methanol blends by adding specific solvents and then to investigate the performance and emission of a compression ignition engine operating with these blends so as to get an alternative for diesel fuel. II. PREPARATION OF DIESEL-METHANOL BLENDS Methanol has very little solubility in diesel fuel. Therefore it must be emulsified into the diesel fuel. Anhydrous methanol added into the solution with diesel fuel, but separation occurs, if the methanol contains more than one-half percent water. Both methanol and ethanol can be emulsified in the diesel fuel in either stabilized or unstabilized form. The stabilized emulsions require a large volume of chemical surfactant to prevent separation of the alcohol and diesel fuel. This volume is roughly equal to the volume of alcohol present. On the other hand, the unstabilized emulsions do not require the chemical stabilizer, but they separate very quickly and must be emulsified immediately before injection into the engine. Alcohols possess only about one-half or less of the volumetric energy of the diesel fuel, due to which injector output must be increased to deliver full power when operating on alcohol emulsions. Six fractions of diesel-methanol blends were prepared for study named as, Fuel 1 (88:5:5:2), Fuel 2 (85:5:5:5), Fuel 3 (78:10:10:2), Fuel 4 (75:10:10:5), Fuel 5 (68:15:15:2) and Fuel 6 (65:15:15:5). The values in bracket indicate percentage volume of diesel, methanol, oleic & Isobutanol respectively. The fractions of prepared blends are given in Table 1. Table 1: Fuel Proportion in Blends Fuel Base Fuel: Diesel Blended fuel: Methanol Oleic Solvents Isobutanol Fuel 1 (88:5:5:2) Fuel 2 (85:5:5:5) Fuel 3 (78:10:10:2) Fuel 4 (75:10:10:5) Fuel 5 (68:15:15:2) Fuel 6 (65:15:15:5) Fuel Properties: The properties of blends are given in Table 2, whereas fuel properties are given in Table 3. All these fuel blends are tested in engine for varying load on the engine. Table 2: Fuel properties of diesel/methanol blended fuel Property Fuel 1 Fuel 2 Fuel 3 Fuel 4 Fuel 5 Fuel 6 Lower Heating Value (MJ/kg) C (wt %) H (wt %) O (wt %) All rights Reserved 203

3 Property Table 3: Fuel properties of diesel, methanol and solvents Base fuel: Diesel Blended fuel: Methanol 1) Solvents 2) Oleic 3) Isobutanol Chemical Formula C 10.8 H 18.7 CH 3 OH C 18 H 34 O 2 C 4 H 10 O Mole Weight (g) Density (g/cm 3 ) Lower Heating Value (MJ/kg) Heat of Evaporation (kj/kg) Self-Ignition Temp. ( 0 C) Cetane Number C wt. % H wt. % O wt. % III. EXPERIMENTAL SETUP A single cylinder, four stroke, water cooled engine was selected for the test. The specifications of the engine are given in Table 4. The tests were carried out at 27 0 crank angles before top dead centre (btdc) and 30 0 crank angles before top dead centre (btdc) of fuel delivery. The engine used is a single cylinder 4-stroke naturally aspirated C.I. engine made by COMET company having following specifications. Table 4: Specifications of Diesel Engine Bore 80 mm Stroke 110 mm Displacement 553 Compression Ratio 17.5: 1 Rated Power 3.7 kw Rated Speed 1500 rpm Fuel Delivery angle 27 0 btdc 3.1: Experimental Procedure: Tests were carried out on the engine initially by using diesel as a fuel in order to provide base line data. During tests the speed of the engine was kept almost constant at 1500 rpm and engine was loaded as 0%, 25% 50%, 75% and full load. Initially the fuel is injected at 27 0 crank angles before top dead centre (btdc) then tests were carried for each blend i.e. foe F1, F2, F3, F4, F5, F6 and diesel for 0%, 25% 50%, 75% and full load. Each test is carried two times to check the repeatability. The engine was held running at each load step for half an hour. Also the engine is tested for 30 0 crank angles before top dead centre (btdc). During test the various performance parameters were measured by data acquisition system. IV. RESULTS AND DISCUSSION The extensive experiments were carried out by operating the engine at different loads using pure diesel and methanol blended fuels by varying injection angle. The various parameters were measured at steady state working condition of the engine. From the measured parameters the performance parameters computed and its trends are presented in graphical form. These performance parameters are discussed as All rights Reserved 204

4 4.1: Brake Thermal Efficiency (BTE): The thermal efficiency at two settings of fuel delivery angle is illustrated in Fig. 1 and Fig. 2. The results show that oxygen containing fuels are favorable to increase the thermal efficiency. For 15% of methanol it shows decrease in efficiency. This suggests that increase in efficiency is beneficial at small values of methanol addition. The addition of methanol to diesel will result in oxygen enrichment in diesel-methanol spray. Figure 1. Variation of BTE with Load at Fuel Injection 27 0 btdc Figure 2. Variation of BTE with Load at Fuel Injection 30 0 btdc 4.2: Brake Specific Fuel Consumption (BSFC): Figures 3 & 4 show the brake specific fuel consumption (BSFC.) at both fuel injection angles for different loads. The trend shows that fuel consumption increases with methanol mass percentage in the diesel fuel owing to the decrease in calorific value of methanol. The methanol content of 15% has major increase in its value at low load and overload conditions. Figure 3. Variation of BSFC with Load at Fuel Injection 27 0 All rights Reserved 205

5 Figure 4. Variation of BSFC with Load at Fuel Injection 30 0 btdc 4.3: Exhaust Gas Temperature (EGT): Exhaust Gas Temperature (EGT) reflects on the status of combustion inside the combustion chamber. From the figures it can be seen that there is no much variation in the EGT at all load conditions for different injection angles for all fuels. A closer look of Figure 5 & 6 reveals the engine operating parameters which indicated minimum BSFC and maximum BTE were the once which contributed to minimum Exhaust Gas Temperatures. It shows that EGT lines for various fuel blends are closer to each other in a narrow band for different injection angle indicating similar performance of different blends at this injection angle. The increase in EGT with load is obvious from the simple fact that more amount of fuel was required in the engine to generate that extra power needed to take up the additional loading. Figure 5. Variation of EGT with Load at Fuel Injection 27 0 All rights Reserved 206

6 Figure 6. Variation of EGT with Load at Fuel Injection 30 0 btdc 4.4: Smoke Density: The presence of oxygen in combustion chambers causes complete combustion of fuel resulting in decrease of smoke in exhaust gases. Figure 7 and Fig. 8 shows the smoke emission with methanol for different load values at standard and advanced fuel injection timing. It is seen that methanol added to the diesel fuel is effective in reducing smoke. The purpose of using oxygen containing fuel blend is expected to decrease the engine smoke because it is supplying more oxygen to make it burn completely. The results clearly show that the engine smoke reduced markedly with the addition of methanol in the diesel fuel for both fuel delivery angles. This is reasonable because the oxygen containing fuel blends can reduce the fuel rich spray region. The oxygen enrichment provided by methanol is beneficial to smoke reduction and the improvement in fuel evaporation. Figure7. Variation of HSU with Load at Fuel Injection 27 0 All rights Reserved 207

7 Figure 8. Variation of HSU with Load at Fuel Injection 30 0 btdc V. CONCLUSIONS Based on the results of this investigation following conclusions can be drawn; 1. The mass fuel consumption increases with methanol percentage in diesel fuel because of low calorific value of fuel, but the diesel equivalent BSFC shows a slight decrease with methanol addition owing to the improvement of combustion with oxygen enrichment. 2. Thermal efficiency increases with methanol (or oxygen) mass fraction in diesel fuel. Increase in efficiency is advantageous at small percentage of methanol additions. Further increase in fuel delivery advance angle will achieve better thermal efficiency. 3. Remarkable reduction in exhaust smoke can be achieved when operating on diesel methanol fuel blends. Smoke reduction shows linear relationship with methanol percentage or oxygen mass percentage in diesel fuel. REFERENCES [1] Caro, P., Mouloungui, Z., Vaitilingom, G. and Berge, J. "Interest of Combining an Additive with Diesel-Ethanol Blends for Use in Diesel Engines". Fuel 80 (2001); [2] Wang, H., Huang, Z., Zhou, L., Jiang, D. and Yang, Z. Investigation on Emission Characteristics of a Compression Ignition Engine with Oxygenated Fuels and Exhaust [3] Gas Recirculation, Proc. Instn. Mech. Engrs, Part D Journal of Automobile Engineering, Vol. 214, [4] Miyamoto, N., Ogawa, H., Nurun, N., Obata, K. and Arima, T. Smokeless, Low NO x, High Thermal Efficiency and Low Noise Diesel Combustion with Oxygenated Agents as Main Fuel, SAE Trans., 1998, , [5] Ali, Y., Hanna, M., and Borg, J. Optimization of Diesel. Methyl Tallowate and Ethanol Blends for Reducing Emissions from Diesel Engine, Bioresource Technol., 1995, 52, [6] Pucher, H., and Sperling, E. Improved Exhaust Gas Quality from Diesel Engines Running on-butanol/diesel Fuel Mixtures, SAE Trans., 1981, [7] Lawson, A., Last, A., Desphande, A., and Simmons, E. Heavy Duty Truck Diesel Engine Operation on Unstabilised Methanol/Diesel Fuel Blends, SAE Trans., 1981, , [8] Huang, Z., Lu, H., Jiang, D., Zeng, K., Liu, B., Zhang, J., and Wang, X. Combustion Characteristics and Heat Release Analysis of a Compression Ignition Engine operating on Diesel/Methanol Blends, Proc. Instn. Mech. Engrs, Part D Journal of Automobile Engineering, Vol. 218, [9] Murayama, T., Zheng, M., Chikahisa, T., and Oh, Y. Simultaneous Reduction of Smoke and NOx from DI Diesel Engine with EGR and Dimethyl Carbonate, SAE Trans., 1995, , All rights Reserved 208