IJCRR - 4(19), October, 2012
Pages: 202-208
Date of Publication: 15-Oct-2012
Print Article
Download XML Download PDF
PERFORMANCE AND EMISSION CHARACTERISTICS OF DIESEL ENGINE FUELED WITH SESAME OIL METHYL ESTER BLENDS
Author: G.G. Srinivas, K. Apparao, G.V.N. Kumar, Rajesh Guntur
Category: Technology
Abstract:The rapidly increasing petroleum prices, uncertainties concerning its availability and growing concern of the environment revived research interests on the usage of alternative fuels in internal combustion engines. Biodiesel is a methyl or ethyl ester of fatty acids made from vegetable oils and animal fat. It can be used in diesel engines with very little or no engine modifications. In this present work the experimental investigations are carried out on the test engine operated with methyl esters of sesame oil and diesel blends. Comparative measures of performance parameters, smoke opacity, unburned hydrocarbons (HC), carbon monoxide (CO), Oxides of nitrogen (NOx), Carbon dioxide (CO2) and unused oxygen (O2) emissions are calculated. In the initial stage the tests are conducted on the four stroke single cylinder water cooled direct injection diesel engine by using diesel and base line data is generated. In the second stage, tests are carried out using Methyl esters of sesame oil with diesel blends at various loads and compared with the base line data obtained earlier. Engine performance in terms of higher brake thermal efficiency and lower brake specific fuel consumption and lower emissions (HC, CO, NOx) has observed for 20% Sesame oil and 80% diesel. the burning. This causes lower temperatures inside the cylinder and low NOx emissions in the exhaust gases. Exhaust gas temperatures of the blend are lower than those of the diesel fuel due to the lower heating value of the blend. It is proved that the lower temperature causes low NOx emissions when compared with diesel fuel. The variation of NOx emissions for D100 and SME blends with B.P is shown in Figure 4. NOx content is drastically reduced for S10 and S20 blends compared with D100 which is 1236ppm to 1061ppm and 1040ppm respectively, means it is reduced by 14% and 15% for the blends S10 and S20 compared to Diesel. Smoke The variation of smoke density with brake power of the engine for D100, S10, S20 and S30 by volume of concentrations is shown in Figure 5. It was observed that the smoke density of all the blends is lower than that of diesel at maximum load. The maximum smoke density recorded using diesel was 79.6 HSU and 58.8 HSU for S10 and 60 HSU for S20 at maximum brake power. Because of the oxygen enrichment contained by S10 and S20, it improves fuel evaporation during diffusion combustion which subsequently reduces the smoke density. The decrease in smoke density by percentage compared to D100 for S10 and S20 is 26% and 24.6% respectively. But for the S30 blend Smoke density slightly increased because of increased viscosity and incomplete combustion. Carbon Monoxide CO emission depending on many parameters such as air\?fuel ratio and the engine temperature are the causes of exhaust gas emissions in the internal combustion engine. It is one of the toxic products of combustion due to the improper burning of hydrocarbon (HC). Figure 6 shows the variation of CO emissions for D100 with other blends. From the plot it is observed that the CO emissions at full load for D100, S10, S20 and S30 are 0.07%, 0.06%, 0.07% and 0.06% respectively. It is clear from the plot that CO emissions decreases with S10, S30 blends, produced significantly lower CO emissions than that of diesel fuel because of Oxygen availability from this blend for complete combustion. Unburned Hydrocarbons The variation of HC with brake power of the engine for D100 and S10, S20, S30 blends are shown in Figure 7. Because of the oxygen enrichment contained by S10 and S20 improves fuel evaporation during diffusion combustion which slightly reduced the unburned Hydrocarbons. For D100, HC content is 58ppm but for S10, S20 it is reduced to 56ppm. These reductions indicate a more complete combustion of the fuel. The presence of oxygen in the fuel was thought to promote complete combustion. Unburned hydrocarbons are reduced by 3.4% using the blends S10 and S20 as compared with diesel. Carbon Dioxide The variation of CO2 with brake power of the engine for D100 and S10, S20, S30 blends are shown in Figure 8. From the plot it is observed that the CO2 content for D100, S10, S20, S30 blends at full load conditions are 8.5%, 8.4%, 8.3% and 8.5% respectively. But there is no considerable change in CO2 only slight decrease in CO2 occurred for S20 blend compared to D100. Since enough amount of oxygen is available for complete combustion. The CO2 emissions from a diesel engine indicate how efficiently the fuel is burnt inside the combustion chamber. The esterbased fuel burns more efficiently than diesel. CONCLUSIONS From the above discussions it was proved that exhaust emissions of the sesame oil\?diesel mixture were lower than that of using diesel and it can be used as an alternative fuel in view of reduced environmental pollution by reduction in HC, NOx, CO emissions and also in increased performance parameters like brake thermal efficiency and decreased brake specific fuel consumption. Properties of S20 are nearer to diesel and it is. ACKNOWLEDGEMENT
The authors acknowledge the immense help received from the scholars whose articles are cited and included in references of this manuscript. The authors are also grateful to authors / editors / publishers of all those articles, journals and books from where the literature for this article has been reviewed and discussed.
Keywords: Bio fuels, bsfc, emissions, Sesame methyl esters
Full Text:
INTRODUCTION
In present days the utilization of diesel engines are more compared with petrol engines for domestic purposes because of their higher performance and low cost of fuel. Since the petroleum crises in 1970s, the rapidly increasing petroleum prices and uncertainties concerning its availability, growing concern of the environment and the effect of greenhouse gases (GHGs) during the last decades, has revived more and more interests in the use of vegetable oils as a substitute of fossil fuel. Vegetable oils are widely available from various sources, and the glycerides present in the oils can be considered as a viable alternative for diesel fuel. They have good heating power and provide exhaust gas with almost no sulfur and aromatic polycyclic compounds. Vegetable oils are produced from plants, their burning leads to a complete recyclable carbon dioxide (CO2). In diesel engines several alternative fuels can be used without any engine modifications to compensate the petroleum based fuel crises. Bello E.I et al [1] used castor oil and blends in a diesel engine to evaluate the load test, speed test and performance test. Castor oil had very high kinematic viscosity which was reduced by using high molar ratio during transesterification but still needed to be blended with diesel fuel to bring it to the limits for biodiesel. The torque and power output characteristics are about 10% less than that for diesel fuel but the load carrying capacity is about 20% higher as a result of it oxygen content which allowed for more complete combustion and operate to a lower speed. Sehmus Altun et al [6] used a blend of 50% sesame oil and 50% diesel fuel was used as an alternative fuel in a direct injection diesel engine. Engine performance and exhaust emissions were investigated and compared with the ordinary diesel fuel in a diesel engine. The experimental results show that the engine power and torque of the mixture of sesame oil– diesel fuel are close to the values obtained from diesel fuel and the amounts of exhaust emissions are lower than those of diesel fuel. Analyzing review on various alternate fuels it is concluded that the Sesame oil [6] can be used with the diesel with higher percentages (up to 50%). The experimental results show that the engine performance parameters of the mixture of sesame oil–diesel fuel are close to the values obtained from diesel fuel and the amounts of exhaust emissions are lower than those of diesel fuel. Preparation of sesame oil methyl esters The formation of methyl esters by transesterification of vegetable oil requires raw Sesame oil, 15% of methanol & 5% of sodium hydroxide on mass basis. However, transesterification is an equilibrium reaction in which excess alcohol is required to drive the reaction very close to completion. The vegetable oil was chemically reacted with an alcohol in presence of a catalyst to produce methyl esters. Glycerol was produced as a by-product of transesterification reaction. The mixture was stirred continuously and then allowed to settle under gravity in a separating funnel. Two distinct layers form after gravity settling for 24 hours. The upper layer was of ester and lower layer was of glycerol. The lower layer was separated out. The methyl ester was then blended with diesel in various concentrations for preparing biodiesel blends to be used in CI engine for conducting various engine tests.
Properties of the Bio-diesel
The properties of sesame oil methyl ester were found in the fuels laboratory. The results obtained are shown in Table 1.
EXPERIMENTAL SETUP
The experimental set up shown in Figure (a) is a single cylinder, four-stroke, naturally aspirated, DI diesel engine. The set up is provided with necessary instruments like Rope brake dynamometer, Smoke meter (Netel’s-NPM-DSM), Gas analyzer (Netel’s-NPM-MGA-2) etc., for performance and emission analysis. Specifications of test engine are shown in Table 2.
RESULTS AND DISCUSSION
The performance and emission characteristics of a high speed diesel engine at various loads from no load to full load fuelled with sesame oil methyl esters compared with diesel are discussed below as per the results obtained.
Specific Fuel Consumption
The BSFC obtained from calculations was plotted against brake power and compared the results for different blends of fuels as shown in Figure 1. The plot reveals that the BSFCs obtained at full loads for D100 and S10, S20, S30 blends are 0.26 Kg/KW-hr, 0.25 Kg/KW-hr, 0.25 Kg/KW-hr and 0.27 Kg/KW-hr respectively. From the plot it is observed that BSFC is decreasing compared to D100 for S10 and S20 blends. Considerable decrease in BSFC has been observed for both S10 and S20 blends. The BSFC of the engine decreased because of better combustion due to the availability of excess oxygen in these blends. BSFC for D100 is 0.26 kg/kW-hr but for S10 and S20 it is 0.25kg/kW-hr. The percentage of decrease in BSFC for both these blends is 3.8% compared to diesel.
Mechanical Efficiency
The Mechanical efficiencies which were obtained from calculations are plotted against brake power and compared the results for all the blends when using diesel are shown in Figure 2. From the plot it is observed that the mechanical efficiencies obtained at full loads for D100, S10, S20, S30 are 63.11%, 65%, 60.6% and 60% respectively. The variation of Mechanical efficiency has been observed with various blends compared to Diesel. But considerable change in Mechanical efficiency has not observed since the fuel properties are not so different for diesel and other blends. Brake Thermal Efficiency The brake thermal efficiencies which were obtained from calculations was plotted against brake power and compared the results for different blends of fuels as shown in Figure 3 for S10,S20,S30 and D100. From the Plot it is observed that BTH at full load conditions for D100, S10, S20 and S30 are 32.82%, 33.8%, 34.6% and 32% respectively. The maximum BTH is observed for S20 blend. As the blend mixture strength is increasing the calorific value decreases and there will be variation in the brake thermal efficiency. From graph it is clear that BTH is more for the blends when load reaches the maximum. But only slight improvement in BTH has been observed for S20 at full load as 34.6% and for D100 it is 32.82%. The percentage of increase in BTH by using S20 is 4.6% compared to diesel. The reduction in viscosity because of increase in cylinder temperatures at maximum loads leads to better evaporation and mixing with air resulted in more complete fuel combustion caused the maximum thermal efficiency. It was also observed that the brake thermal efficiencies were closer to each other for all blends and diesel.
Oxides of Nitrogen
The most important factor for the emissions of NOx is the combustion temperature in the engine cylinder and the local stoichiometry of the mixture. The reduction of NOx emissions is possibly due to the smaller calorific value of the blends. Cetane number is also effective in NOx emissions. Cetane number of the sesame oil is smaller than that of the diesel fuel. The smaller the cetane number,the longer the ignition delay and the burning. This causes lower temperatures inside the cylinder and low NOx emissions in the exhaust gases. Exhaust gas temperatures of the blend are lower than those of the diesel fuel due to the lower heating value of the blend. It is proved that the lower temperature causes low NOx emissions when compared with diesel fuel. The variation of NOx emissions for D100 and SME blends with B.P is shown in Figure 4. NOx content is drastically reduced for S10 and S20 blends compared with D100 which is 1236ppm to 1061ppm and 1040ppm respectively, means it is reduced by 14% and 15% for the blends S10 and S20 compared to Diesel. Smoke The variation of smoke density with brake power of the engine for D100, S10, S20 and S30 by volume of concentrations is shown in Figure 5. It was observed that the smoke density of all the blends is lower than that of diesel at maximum load. The maximum smoke density recorded using diesel was 79.6 HSU and 58.8 HSU for S10 and 60 HSU for S20 at maximum brake power. Because of the oxygen enrichment contained by S10 and S20, it improves fuel evaporation during diffusion combustion which subsequently reduces the smoke density. The decrease in smoke density by percentage compared to D100 for S10 and S20 is 26% and 24.6% respectively. But for the S30 blend Smoke density slightly increased because of increased viscosity and incomplete combustion. Carbon Monoxide CO emission depending on many parameters such as air–fuel ratio and the engine temperature are the causes of exhaust gas emissions in the internal combustion engine. It is one of the toxic products of combustion due to the improper burning of hydrocarbon (HC). Figure 6 shows the variation of CO emissions for D100 with other blends. From the plot it is observed that the CO emissions at full load for D100, S10, S20 and S30 are 0.07%, 0.06%, 0.07% and 0.06% respectively. It is clear from the plot that CO emissions decreases with S10, S30 blends, produced significantly lower CO emissions than that of diesel fuel because of Oxygen availability from this blend for complete combustion. Unburned Hydrocarbons The variation of HC with brake power of the engine for D100 and S10, S20, S30 blends are shown in Figure 7. Because of the oxygen enrichment contained by S10 and S20 improves fuel evaporation during diffusion combustion which slightly reduced the unburned Hydrocarbons. For D100, HC content is 58ppm but for S10, S20 it is reduced to 56ppm. These reductions indicate a more complete combustion of the fuel. The presence of oxygen in the fuel was thought to promote complete combustion. Unburned hydrocarbons are reduced by 3.4% using the blends S10 and S20 as compared with diesel. Carbon Dioxide The variation of CO2 with brake power of the engine for D100 and S10, S20, S30 blends are shown in Figure 8. From the plot it is observed that the CO2 content for D100, S10, S20, S30 blends at full load conditions are 8.5%, 8.4%, 8.3% and 8.5% respectively. But there is no considerable change in CO2 only slight decrease in CO2 occurred for S20 blend compared to D100. Since enough amount of oxygen is available for complete combustion. The CO2 emissions from a diesel engine indicate how efficiently the fuel is burnt inside the combustion chamber. The esterbased fuel burns more efficiently than diesel.
CONCLUSIONS
From the above discussions it was proved that exhaust emissions of the sesame oil–diesel mixture were lower than that of using diesel and it can be used as an alternative fuel in view of reduced environmental pollution by reduction in HC, NOx, CO emissions and also in increased performance parameters like brake thermal efficiency and decreased brake specific fuel consumption. Properties of S20 are nearer to diesel and it is proved that SME can be used as alternate fuel for existing diesel engines.
ACKNOWLEDGEMENT
The authors acknowledge the immense help received from the scholars whose articles are cited and included in references of this manuscript. The authors are also grateful to authors / editors / publishers of all those articles, journals and books from where the literature for this article has been reviewed and discussed.
References:
1. Bello E.I and Makanju, “Production, Characterization and Evaluation of Castor oil Biodiesel as Alternative Fuel for Diesel Engines”, Journal of Emerging Trends in Engineering and Applied Sciences , 2011,PP 525-530.
2. Athanasios Balafoutis, Spyros Fountas, Athanasios Natsis and George Papadakis “Performance and Emissions of Sunflower, Rapeseed, and Cottonseed Oils as Fuels in an Agricultural Tractor Engine Athanasios” International Scholarly Research Network ISRN Renewable Energy,2011, Article ID 531510, 12 pages.
3. Y. V. V. Satyanarayana Murthy, “Performance of Tobacco Oil-Based BioDiesel Fuel In A Single Cylinder Direct Injection Engine” International Journal of the Physical Sciences Vol. 5(13), 18 October, 2010, pp. 2066-2074.
4. M.Pugazhvadivu1 and G.Sankaranarayanan “Experimental Studies on A Diesel Engine Using Mahua Oil As Fuel”, Indian Journal of Science and Technology, Vol. 3 No. 7 (July 2010) , PP 787-791.
5. Md. Nurun Nabi and S. M. Najmul Hoque “Biodiesel Production From Linseed Oil and Performance Study of a Diesel Engine With Diesel Bio-Diesel Fuels” Journal of Mechanical Engineering, vol. ME39, No.1, June 2008, pp.40-44.
6. S-ehmus Altun, Hu¨ samettin Bulut, Cengiz O¨ner “The Comparison of Engine Performance and Exhaust Emission Characteristics of Sesame Oil–Diesel Fuel Mixture With Diesel Fuel In a Direct Injection Diesel Engine”, Renewable Energy 33 (2008), pp1791–1795.
7. V.R. Sivakumar, V.Gunaraj, P. Rajendran “Statistical Analysis on The Performance of Engine With Jatropha Oil as an Alternate Fuel” International Journal of Engineering Science and Technology Vol. 2(12), 2010, pp.7740-7757.
8. K. Anbumani and Ajit Pal Singh. “Performance of Mustard and Neem Oil Blends With Diesel Fuel In C.I Engine” APRN journal of engineering and applied sciences, vol. 5, no. 4, April 2010.,pp 14-20
9. Niraj S. Topare, V.C. Renge, Satish V. Khedkar, Y.P. Chavan and S.L. Bhaga “Biodiesel From Algae Oil as an Alternative Fuel For Diesel Engine” International Journal of Chemical, Environmental and Pharmaceutical Research, Vol. 2, No.2-3, May-December-2011,pp 116-120.
10. M. Mani, C. Subash, G. Nagarajan “Performance, Emission and Combustion Characteristics of A DI Diesel Engine Using Waste Plastic Oil” Applied Thermal Engineering, volume 29,Issue 13, September 2009, Pages 2738-2744.
11. Sagar Pramodrao Kadu, Rajendra H. Sarda “Experimental Investigations on The Use of Preheated Neat Karanja Oil as Fuel in a Compression Ignition Engine” World Academy of Science, Engineering and Technology 72, 2010, pages 540-544.
12. T.K. Gogoi, D.C. Baruah “The Use of Koroch Seed Oil Methyl Ester Blends as Fuel In a Diesel Engine” Applied Energy Volume 88, Issue 8, August 2011, Pages 2713-2725.
|