Government Engineering College, Bhuj.

Research Paper THE PERFORMANCE OF MULTI CYLINDER DIESEL ENGINE FUELLED WITH BLEND OF DIESEL AND NEEM OIL BIODIESEL Suthar Dinesh Kumar L. a*, Dr. Rathod Pravin P. b, Prof. Patel Nikul K. c Address for Correspondence a P.G. student, 4 th Semester Automobile Engineering, b Associate Professor, Mechanical Engineering Department, Government Engineering College, Bhuj. c Assistant Professor, Mechanical Engineering Department, Faculty of Engg. & Technology, M.S. University, Vadodara. ABSTRACT This paper deals with the experimental work carried out to evaluate the effects of neem oil biodiesel/diesel blends on the performance and emission characteristics of an indirect injection, multi cylinder, 4-strokes, and water cooled compression ignition engine. The investigations carried out in studying the fuel properties of Neem biodiesel and its blend with diesel fuel from 10 to 30% by volume and in running a diesel engine with these fuels. Engine tests have been carried out with the aim of obtaining comparative measures of brake power, brake specific fuel consumption, Exhaust gas temperature and emissions such as CO, NO X and HC to evaluate and compute the behavior of the diesel engine running on above mentioned fuels. The reduction in exhaust emissions together with increase in brake power, brake thermal efficiency and reduction in brake specific fuel consumption make the blends of 20% Neem biodiesel with 80% diesel (B20) a suitable optimize alternative fuel for diesel and could help in controlling air pollution and no need to do any modification in diesel engine. Engine performance values such as brake power, brake thermal efficiency and brake specific fuel consumption have been investigated on fixed engine speed with variation of loads and emissions such as CO, NO X and HC also investigated, According to the results, the best performance and less emission obtain with in B20 blend from various test fuels. KEY WORDS: Biodiesel, Performance, Emission, CI Engine. 1. INTRODUCTION Diesel engines are the prime source of transportation, power generation, marine applications, agriculture applications etc. hence diesel is being used largely, but due to gradual depletion of world petroleum reserves and the impact of environmental pollution of increasing exhaust emissions, there is an urgent need for suitable alternative fuels for use in diesel engines. In view of this, efforts are being made throughout the world to reduce the consumption of liquid petroleum fuels wherever is possible. Two general approaches are in use. First is to switch over the energy consumption devices on alternative energy source which are either abundant or are reproducible. The second is to enhance the efficiency of combustion devices. This can be achieved by understanding the physicochemical processes involved during the combustion. Non edible vegetable oils like Neem oil, Jatropha oil, Mahuva oil, karanja oil are considered as alternate fuels to diesel.the advantages of these oils are eco-friendly and can be produced easily in rural areas, where there is an acute need for modern forms of energy. The present production of Neem oil seeds is approximately 500 million tons per annum, in expellers, whole dried fruits, depulped seeds and kernels, yield 4-6%, 12-16% and 30-40% oil respectively. Major fatty acid composition of Neem oil are Palmitic acid 19.4%,Stearic acid 21.2%,Oleic acid 42.1%,Linoleic acid 14.9%, Arachidic acid 1.4% by weight. [1] Biodiesel has higher viscosity, density, pour point, flash point and cetane number than diesel fuel. Biodiesel is an oxygenated fuel which contains 10 15% oxygen by weight. These facts lead biodiesel to total combustion and less exhaust emissions than diesel fuel. [2] Vegetable oils have become more attractive because of its environmental benefits and the fact that it is made from renewable resources. Vegetable oils are a renewable and potentially inexhaustible source of energy with an energetic content close to diesel fuel. The vegetable oil fuels were not acceptable because they were more expensive than petroleum fuels. However, with recent increase in petroleum prices and uncertainties concerning petroleum availability, there is renewed interest in vegetable oil fuels for diesel engine [3]. Furthermore also the energy content or net calorific value of biodiesel is about 12% less than that of diesel fuel on a mass basis. The major problem associated with the use of pure vegetable oils as fuels for diesel engines are caused by high fuel viscosity in compression ignition engine. These problems can be minimized by the process of Transesterification. Using optimized blend of biodiesel and diesel can help reduce some significant percentage of the world s dependence on fossil fuels without modification of CI Engine, and it also has important environmental benefits. For example using optimized blend of biodiesel and diesel instead of the conventional diesel fuel significantly reduces the exhaust emissions particulate matter (PM), carbon monoxide (CO), sulfur oxides (SOx), and unburned hydrocarbons (HC). [4, 5, 6, 7] 2. EXPERIMENTAL SET UP The experimental setup consists of a four cylinder, four strokes, naturally aspirated, in-direct injection, water cooled CI engine have been used to carry out experimental investigations which is connected to eddy current dynamometer for loading an engine. It is situated in Thermal Engineering Laboratory at Faculty of Engineering and Technology, M.S.University, Vadodara. Experiments are conducted with pure diesel and blends of Neem oil biodiesel and diesel. Electronic Controller Device (data acquisition system) connected with engine which displays all different parameters at every 5 seconds related with experimental work using different sensors. Electronic Controller Device measures Engine Inlet and Exhaust Temperature in degree centigrade, Load Applied on Dynamometer in kg., Speed of engine in RPM, which are display digitally on panel board which is shown in figure 1. The detailed specifications of the engine are given below in table 1, Exhaust gas analyzer shown in figure 2 is used for measurement of different pollutants. Prima made exhaust gas analyzer is capable to measure CO, CO 2, HC, NO, NO 2, excess

air and flue gas temperature. Range and resolution for each parameter is shown in table 2. The various components of the experimental setup shown in figure 1. Table 1 Engine Specifications Table 2 Exhaust Gas Analyzer Specifications Figure 1 Experimental setup Figure 2 Exhaust Analyzer BLEND PREPARATION The fuel selected for testing in the engine to find the performance of the engine is Neem oil biodiesel blend with diesel. Neem oil biodiesel is having kinematic viscosity 18 cst. at 27ºC. The blends of Neem oil biodiesel and diesel are prepared on volume basis as follows: B10: 10% Neem oil biodiesel and 90% Diesel, B20: 20% Neem oil biodiesel and 80% Diesel, B30: 30% Neem oil biodiesel and 70% Diesel. The instrument used for measuring volumes of each oil is measuring flask of capacity 500ml as shown in Figure 3. Oils are measured according to the blend ratios. 3. RESULTS AND DISCUSSION 3.1 Properties and Characteristic of Fuel and Blends The properties of various blend tested at Microtech research and analytical lab, vadodara. The calorific value of diesel fuel is found 41689.96 kj/kg and Neem biodiesel is 36770.23 kj/kg. Calorific value for different blends B10, B20, B30 has been calculated. B20 has calorific value of 40706.01 kj/kg which is comparable to diesel. Neem biodiesel has 11.80% lower energy content than diesel. Lower calorific value of Neem oil biodiesel is mainly due to oxygen content of Neem oil biodiesel and increases brake specific fuel consumption compared to diesel. Moreover, maximum power produced using Neem oil biodiesel is less compared to diesel because of lower calorific value. As pump injects fuel on volumetric basis hence less amount of energy injected during cycle with Neem oil biodiesel compared to diesel. Higher or lower kinematic viscosity play very vital role when Neem oil biodiesel is used in engine without modification in injection pressure as this will result in change of fuel atomization and distribution inside cylinder. Kinematic viscosity for pure Neem oil biodiesel and B20 are 18 cst and 4.5cSt respectively, whereas for diesel kinematic viscosity measured is 3.6cSt. Neem oil biodiesel has higher kinematic viscosity compared to diesel. B20 has very comparable viscosity to diesel but with higher blend percentage kinematic viscosity increases and results into larger droplet diameter of fuel. Due to higher kinematic viscosity Neem oil biodiesel requires higher injection pressure than diesel. Specific density of Neem oil biodiesel is 0.84g/cc where as diesel has specific density of 0.82g/cc. Due to higher specific density of Neem oil biodiesel, specific fuel consumption will be less than diesel but due to lower calorific value net effect is increase in specific fuel consumption. Other properties of various test fuels shown in table 3. In this table compares the flash point temperature, carbon residue, sulphur content and ash content for diesel, Neem oil biodiesel and various blends. Flash point of diesel is 55 C, which is lower compared to 105 C of the Neem oil biodiesel. Neem oil biodiesel has higher flash point temperature of 105 C compared to diesel. Hence, it is comparatively safer to transport and store Neem oil biodiesel than diesel. Sulphur content of Neem oil biodiesel is 0.01 %w/w, where as diesel has sulphur content of 0.003 %w/w. Ash content and carbon residue value for diesel is 0.002% w/w and 0.2% w/w respectively, which is 80% and 95% lower compared to Neem oil biodiesel. Table 3 Properties of Test Fuels Figure 3 flask (500ml)

3.2 Effect of Bio-diesel blending on CI engine 3.2.1 Engine performance parameters Figures 4, 5 and 6 compare brake thermal efficiency, brake specific energy consumption and exhaust gas temperature with diesel and different blends of diesel and Neem biodiesel as fuels at varying brake power. Figure 4 Variations in Break Thermal Efficiency with Brake Power and Biodiesel Percentage in Blend Figure 5 Variations in Break Specific Energy Consumption with Brake Power and Biodiesel Percentage in Blend Figure 6 Variations in Exhaust Gas Temperature with Brake Power and Biodiesel Percentage in Blend Figure 4 clearly indicates, as brake power increases As load on engine increases cylinder temperature the brake thermal efficiency increases for all fuels, increases which results in to more complete diesel and its blends like B10, B20, and B30. This combustion of fuel. Hence BTE is showing may be due to at part load, lower cylinder increasing trend for increasing brake power or load. temperature results in incomplete combustion of fuel. However, increasing brake power further shows

reduction in BTE for all fuels. The reason behind this may be, as load increases the fuel air ratio increases and reduction in excess air available. This will result in again incomplete combustion of fuel. Moreover, at high temperature losses due to dissociation take place. In combine effect, there will be decrease in brake thermal efficiency. Maximum value of BTE with diesel fuel obtained is 29.89% at brake power of 9.34 KW. For B20 fuel, the maximum thermal efficiency obtained is 30.50% at brake power of 9.34 KW. Maximum BTE of B20 fuel is approx. 2.04% higher compared to diesel. Higher brake thermal efficiency of B20 fuel is contributed towards oxygen content of Neem oil biodiesel, which helps in complete combustion of fuel. Reduction in CO percentage further strengthens above reason. The second reason behind this may be higher cetane number of Neem oil biodiesel, which results in lower ignition delay and hence maximum pressure developed in the cycle moves close to the TDC. There is an added advantage of reduction in duration of combustion with Neem oil biodiesel as fuel. Using B30 as fuel, maximum efficiency attained is 29.46 % at brake power of 7.7 KW. Which is 2.6 % higher compared to diesel fuel. BTE with B 30 as fuel is somewhat high than diesel but lower than B20 fuel at all loads. The reason behind this may be higher kinematic viscosity of Neem oil biodiesel. As Neem oil biodiesel percentage increases the kinematic viscosity increases and hence larger droplet diameter forms during atomization. These large droplets requires more time for complete combustion and hence results in incomplete combustion and finally brake thermal efficiency. Another reason may be higher cetane number of Neem oil biodiesel, which may shifts the maximum pressure away from TDC which results in lower BTE at higher blend percentage. Peak value of BTE for diesel, B10, B20, B30, 29.89%, 28.65%, 30.50%, and 29.46%, respectively. The reduction in brake thermal efficiency for B10 is 4.15% compared to diesel and B30 is 3.41% compared to B20 fuel. With lower percentage of Neem oil biodiesel in blend maximum brake thermal efficiency is achieved at lower brake power i.e. at 7.62KW where as with higher Neem oil biodiesel percentage in blend maximum brake thermal efficiency is achieved then brake power of 9.34 KW. The reason behind this may be higher kinematic viscosity of Neem oil bio-diesel fuel. Figure 5 shows variations in BSEC with brake power and Neem oil biodiesel percentage in blend. Brake specific energy consumption analysis is done instead of brake specific fuel consumption to account the effect of lower calorific value of Neem oil biodiesel compared to diesel. Brake specific fuel consumption may be higher even though brake thermal efficiency is higher with Neem oil bio-diesel blends compared to diesel fuel. This is due to lower calorific value of Neem oil bio-diesel results in more amount of fuel consumption for same energy input compared to diesel. Neem oil bio-diesel has approximately 11% lower energy density compared to diesel. At brake power of 2.13 KW, BSEC is approximately 100% higher compared to BSEC at brake power of 9.34 KW for all fuels. Further, with increase in load or brake power BSEC for all fuels reduces. BSEC value comes to approximately 50% of initial value at maximum brake power for all fuels. Lower cylinder temperature and lean fuel air ratio at part load results in incomplete combustion and results in higher values of BSEC for all fuels. Minimum BSEC for diesel, B10, B20 and B30 fuels are 12.04 MJ/KW-h, 12.87 MJ/KW-h, 11.80 MJ/KW-h and 12.65 MJ/KW-h respectively. B20 fuel has the lowest BSEC followed by B30 and diesel fuels. B20 fuel show approximately 2% reduction in BSEC compared to diesel fuel. Inbuilt oxygen content, higher cetane number, similar kinematic viscosity and lower combustion duration compared to diesel may be major contributor for lower BSEC of B20 fuel. Lowest BSEC for B10 and B30 fuels are approximately 4.4% and 1.5% higher compared to lowest BSEC for diesel fuel. As Neem oil biodiesel percentage in blend increase, kinematic viscosity of fuel increases. With higher kinematic viscosity and without change in injection pressure, droplet diameter increases and spray pattern also changes for blends as fuels compared to diesel. With higher droplet diameter duration of combustion increases results in shift of peak pressure from TDC. Change in spray pattern with higher droplet diameter may results in fuel impingement on combustion chamber walls and improper mixing of fuel with air. In indirect combustion chamber, low injection pressure makes the problem worst. Moreover, Neem oil biodiesel is less volatile than diesel fuel. In overall result of these effects, BSEC of blended fuels are higher compared to diesel fuel. Figure 6 depicts variations in exhaust gas temperature with brake power. EGT increases with increase in brake power for all fuels. In contrast to BTE and BSEC trends, highest EGT is reached at maximum brake power for all fuels. Maximum EGT measured is 305.68 C using Diesel fuel at brake power of 9.34 KW. Maximum EGT measured is 223.52 o C, 238.07 ºC and 240.10 ºC at 9.34 KW with B10, B20 and B30 fuels respectively. B20 fuel shows approximately 22% reduction in EGT compared to Diesel. However, B20 fuel shows lower EGT compared to diesel fuel. The reason behind this may be the shift of peak cylinder pressure to TDC. As peak pressure is achieved at closer to TDC full expansion of gases during expansion stroke may results in lower EGT at outlet. Lower EGT using B20 fuel also helps in reduction of harmful NOx emissions. With increase in Neem oil bio-diesel percentage in blend the oxygen content increases and hence B30 shows higher exhaust gas temperature compared to B20. Higher EGT can be direct measure of lower brake thermal efficiency as heat losses due to exhaust gases increases with temperature. Moreover, compact combustion chamber and relatively high speed of indirect injection engine results in lower heat loss to cylinder walls contribute for higher EGT. At part load, increase in EGT for Neem oil bio-diesel blends is lower compared to at full load. As we have seen earlier at maximum brake power the rise in EGT is 22%. Hence, one can see that as engine load rises the rate of increase of EGT is higher. Higher EGT has another disadvantage of decrease in brake thermal efficiency. The reason behind is dissociation losses at higher temperature. Further, dissociation results in higher emission of CO. Another method to reduce EGT is to retard the injection timing. Reason behind this is Neem oil bio-

diesel have higher cetane number which reduces delay period and total time of combustion. To blend higher percentage of Neem oil bio-diesel one can have good results by retarding ignition timing [7]. Injection of water in combustion chamber can also reduce EGT. 3.2.2 Engine emission parameters Figure 7, 8 and 9 compare emissions of Carbon monoxide, Oxides of nitrogen and hydrocarbon emission using diesel, B10, B20 and B30 as fuels. Figure 7 shows variations in CO emission with brake power and Neem oil biodiesel percentage in blend. CO emission decreases with load starting from no load for all fuels. Figure 7 Variations in CO Emission with Brake Power and Biodiesel Percentage in Blend Figure 8 Variations in NOx Emission with Brake Power and Biodiesel Percentage in Blend Figure 9 Variations in Hydrocarbon Emission with Brake Power and Biodiesel Percentage in Blend After reaching minimum value, emission of CO trend, variations of CO emission with brake power increases again for all fuels. This rise is continued up are same for all fuels. The reason behind high to the maximum brake power for all fuels. Like NO x emission of CO at no load may be lower cylinder

temperature at no load. As load or brake power increases cylinder temperature also increases. This results in reduction of CO emission and its value reaches to a minimum at brake power of 4.3 KW. Further increase in brake power results in higher emission of CO. The reason behind this is explained here. Everyone knows that diesel engines are quality governed engines. Here the amount of air sucked for each cycle is nearly constant and irrespective of load or brake power of the engine. Initially at no or part load amount of fuel is less and sufficient excess air results in complete combustion of fuel hence reduction in CO emission is seen. However with increase in load or brake power more and more amount of fuel is injected. Thus excess air available and in turn air fuel ratio inside cylinder decreases. This will result in higher CO emission. In addition, indirect injection CI engine emits less amount of CO than direct injection CI engine and well below the emission norms [8]. Emission of CO at no load for diesel, B10, B20 and B30 fuels are 0.042 %/Vol., 0.033 %/Vol., 0.041 %/Vol. and 0.030 %/Vol. respectively. At this load diesel fuel emits highest amount of CO compared to all other fuels. With increase in Neem oil biodiesel percentage in fuel emission of CO reduces at no load. The main reason behind this is inbuilt oxygen content of Neem oil biodiesel fuel. Minimum emission of CO with diesel, B10, B20 and B30 fuels are 0.022 %/Vol., 0.020 %/Vol., 0.018 %/Vol. and 0.021 %/Vol., respectively at brake power of 4.3 KW. In spite of inbuilt oxygen contents of Neem oil biodiesel, with increase in brake power further CO emission is now higher using blends of diesel and Neem oil biodiesel. The main reason behind this is attributed towards the higher kinematic viscosity of Neem oil biodiesel and blends. As percentage of Neem oil biodiesel increases in blend, kinematic viscosity also increases. Further indirect injection CI engine operates at lower injection pressure hence change in kinematic viscosity may drastically change the spray pattern and in turn fuel distribution also. With same injection pressure, atomization of blends and Neem oil biodiesel results in to larger droplet diameter. Larger droplet diameter requires more time for combustion and hence results in incomplete combustion of fuels. This will result in increase amount of CO emission. Moreover, larger droplet diameter may impinging on cylinder wall due to higher momentum worsen the problem. At last, problem of low volatility of Neem oil biodiesel fuel results in higher amount of CO emission with blends and Neem oil biodiesel as fuel compared to diesel. At maximum brake power of 9.4 KW, emission of CO with diesel, B10, B20, and B30 fuels are 0.032 %/Vol., 0.025%/Vol., 0.022 %/Vol. and 0.023 %/Vol. respectively. Figure 8 shows variations in NO x emission with varying brake power and Neem oil bio-diesel percentage in blend. Emission of NO x increases with rise in brake power for all fuels. Variations in NO x emission are similar as EGT with variation in brake power. However, variations in NO x emission with increasing brake power are less compared to EGT. Maximum NO x measured is 336 PPM using B30 at brake power of 9.4 KW. Lowest NO x emission measured is 301 PPM at 9.4 KW with B20 as fuel. B20 fuel shows approximately 12% reduction in NO x emission compared to B30 fuel. Except B20, other blends shows higher NO x emissions compared to diesel fuel. The primary reason of higher NO x emission of Neem oil bio-diesel fuels are contributed towards inbuilt oxygen content, higher cetane number and lower duration of combustion. However, B20 fuel shows lower NO x emissions compared to diesel fuel. The reason behind this may be explained as follow. B20 fuel contents 20% of Neem oil biodiesel and 80% of diesel by volume. Thus overall fuel blend contains lower amount of oxygen compared to Neem oil biodiesel and other blends. NO x formation is dependent upon local high temperature of combustion chamber. Delay period for diesel fuel is high compared to Neem oil biodiesel and hence more of diesel is injected during delay period [7]. Subsequent to this, there will be more amount of fuel which will burn during rapid or uncontrolled combustion period and hence results in high local temperature and in turn NO x emissions. B20 fuel has higher cetane number, hence delay period will reduce and hence amount of fuel injected during delay period is decreased. This will result in lower amount of fuel which will burn during uncontrolled and rapid combustion. This will result in lower combustion temperature and in turn lower NO x emission compared to diesel fuel. Increase of Neem oil biodiesel percentage in blend results in more oxygen content and high cetane number of fuel. Both of these factors will reduce total combustion duration and increase heat release rate. In result of this temperature inside combustion chamber rises and hence increase in NO x emissions. With increase in Neem oil biodiesel percentage in blend the oxygen content increases and hence higher blend shows higher NO x emission compared to diesel. At part load, increase in NO x emission for Neem oil biodiesel blends is lower compared to at full load. At no load, using B10, B20 and B130 as fuels the NO x emission are 180 PPM, 192 PPM and 174 PPM respectively. As we have seen earlier at maximum brake power the rise in NO x emission is 12%. Hence, one can see that as engine load rises the rate of increase of NO x emissions is higher. There are certain techniques to reduce NO x emissions while using Neem oil biodiesel. The most popular are recirculation of exhaust gases. However, this will result in higher emission of CO and HC. Another method to reduce NO x emission is to retard the injection timing. Reason behind this is Neem oil biodiesel have higher cetane number which reduces delay period and total time of combustion[8]. Figure 9 shows variations in HC emission with brake power and Neem oil biodiesel percentage in blend. HC emission is highest at no load for all fuels. The reason behind higher HC emission at no or part load is lower cylinder temperature. Increase in brake power or load results in reduction in HC emission for all fuels. The reason behind this is increase in cylinder temperature with rise in brake power or load. HC emission is lowest at brake power of 9.4 KW for all fuels. Unlike NO x emission, HC emission is highest at no load and decreases with increase in brake power or load. While blending Neem oil biodiesel with diesel results in reduced HC emissions at all load. With increase in Neem oil biodiesel percentage in blend further reduces the HC emission. Highest HC emission for diesel, B10, B20, and B30 fuel are 0.05 %/Vol., 0.04

%/Vol., 0.03 %/Vol. and 0.03 %/Vol., respectively at no load. The primary reason behind less HC emission of Neem oil biodiesel is contributed towards oxygen content of Neem oil biodiesel. As Neem oil biodiesel percentage in blend increases, oxygen content also increases and hence results in reduced amount of HC emissions using Neem oil biodiesel as fuel. At brake power of 9.4 KW all test fuels show HC emissions of 0.01 %/Vol. and are same for all fuels. The reason behind this may be indirect injection combustion chamber of high speed engines emits less amount of CO and HC. Though figure 9 shows same value of HC emission for different blend at maximum brake power, in actual it may be different. Here, lower resolution of exhaust gas analyzer may be unable to distinguish minor change. 4. CONCLUSIONS The following are the conclusion from the results obtained after experimentations while running multi cylinder four strokes, water cooled, and indirect injection diesel engine fuelled with blends of Neem oil biodiesel and diesel. 1. Neem oil biodiesel has comparative properties to diesel. Neem oil biodiesel has 11.81 % lower energy content than diesel. B20 fuel has 2.36% lower energy content than diesel. Maximum power produced using blend of Neem oil biodiesel with diesel can be less compared to diesel because of lower calorific value. B20 has 25% higher kinematic viscosity compared to diesel. Neem oil biodiesel to attain lesser diameter droplet. 2. Brake thermal efficiency with B20 fuel is 30.50%, which are higher compared to 29.89% of diesel. Maximum brake thermal efficiency with B10 and B30 fuels are found 27.97% and 28.45% respectively, which are lower compared to 29.89% with diesel. The higher kinematic viscosity of B30, results in larger droplet diameter and hence in lower brake thermal efficiency. 3. Minimum BSEC for B20 fuel is 11.80 MJ/KW-h. B20 fuel has the lowest BSEC followed by B10, B30 and diesel fuels. Lowest BSEC for B10, B30 and Diesel fuels are 12.87 MJ/KW-h, 12.65 MJ/KW-h and 12.04 MJ/KW-h respectively. Lowest BSEC for B10, B30 and Diesel fuels are approximately 16%, 17% and 11% higher compared to lowest BSEC for B20 fuel. 4. Maximum EGT measure for diesel, B10, B20 and B30 fuels are 305.68 C, 223.52 C, 238.07 C and 240.10 C respectively at full load. EGT increased from no load to full load for all fuels. 5. Minimum emission of CO with diesel, B10, B20, and B30 fuels are 0.022 %/Vol., 0.02 %/Vol., 0.018 %/Vol. and 0.021 %/Vol. respectively at brake power of 4.3 KW. Among all compared fuels CO emission for B20 is lowest followed by B10, B30 and diesel. At maximum brake power of 9.4 KW, emission of CO with diesel, B10, B20, and B30 fuels are 0.032 %/Vol., 0.025 %/Vol., 0.022 %/Vol. and 0.023 %/Vol. respectively. Minimum amount of CO emission is achieved for diesel and B20 fuels are 0.022 %/Vol. and 0.018 %/Vol., respectively at brake power of 4.3 KW. 6. Maximum NO x emission measured for diesel, B10, B20, and B30 fuels are 302 PPM, 316PPM, 301 PPM, and 336 PPM. Except B20, other blends shows higher NO x emissions compared to diesel fuel. Maximum amount of NO x emission is achieved for diesel. 7. Highest HC emissions for diesel, B10, B20, and B30 fuel are 0.05 %/Vol., 0.04 %/Vol., 0.03 %/Vol., and 0.03 %/Vol. respectively at no load. While using increasing % of Blend of neem biodiesel with diesel, emission of HC reduces. 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