Effects of Diary Scum Oil Methyl Ester on a DI Diesel Engine Performance and Emission 1 Benson Varghese Babu, 2 R Suresh & 3 K V Yathish Mechanical Department, Siddaganga Institute of Technology, Tumkur, Karnataka Scientific Assistant, District Bio-fuel Information & Demonstration Center, Tumkur, Karnataka E-mail : benson6617@gmail.com, suresh_tumin@yahoo.co.in & yk82882@gmail.com Abstract - Biodiesel is recognized as a clean alternative fuel or as a fuel additive to reduce pollutant emission from CI engine and minimum cost so there is need for producing biodiesel other than from seed oil. In this study the diary waste scum were used as the raw material to produce biodiesel. Scum oil methyl ester (SOME) is produced in laboratory by tranestrification process. The properties of SOME thus obtained are comparable with ASTM biodiesel standards. Experiments has been carried out to estimate the performance, emission and combustion characteristics of a single cylinder; four stroke diesel engine fuelled with scum biodiesel and its blends with standard diesel. Tests has been conducted using the fuel blends of 10%, 20%, 30% and 100% biodiesel with standard diesel, with an engine speed of 1500 rpm, fixed compression ratio 17.5 and at different loading conditions. The performance parameters elucidated includes brake thermal efficiency, brake specific fuel consumption, and exhaust gas temperature. Keywords: Diary waste scum, Scum oil methyl ester (SOME),Tranestrification,Engine performance. I. INTRODUCTION Alternative fuel derived from vegetable oil and animal fat have increasingly important due to decreasing petroleum resources and increase in pollution problems. Bio-diesel is a cleaner fuel than petroleum diesel and an exact substitute for existing compression engines. Biodiesel has received much attention in the past decade due to its ability to replace fossil fuels, which are likely to run out within a century. Especially, the environmental issues concerned with the exhaust gases emission by the usage of fossil fuels also encourage the usage of biodiesel, which has proved to be eco friendly far more than fossil fuels. Biodiesel is known as a carbon neutral fuel because the carbon present in the exhaust was originally fixed from the atmosphere. Biodiesel can be used in its pure form or can be blended with diesel to form different blends. It can be used in diesel engines with very little or no engine modifications. This is because it has properties similar to mineral diesel. Annual production of milk in India is 150 million tonnes per year. Thousands of large dairies are engaged in handling this milk across the country. In large dairies while cleaning the equipments, the residual butter and related fats which are washed and get collected in effluent treatment plant as a scum. Scum is a less dense floating solid mass usually formed by a mixture fat, lipids, proteins, packing materials etc. This scum is collected in tanks by skimming. Most of the dairies dispose this scum in solid waste disposal site or by incinerating. Waste scum was collected from effluent area and scum oil is extracted from it. Scum oil transestrified to produce SOME, which have fuel properties similar to diesel. In the present study, scum oil methyl ester was considered as a potential alternative fuel for an unmodified diesel engine. Main aim of this study is to investigate the engine performance, emission and combustion characteristics of a diesel engine fuelled with scum oil and its diesel blends compared to those of standard diesel. II. METHODOLGY A. Preparation Of Scum oil The scum collected from the KMF, Tumkur (Karnataka milk federation) diary is heated and filtered to remove waste particle like sand, packing materials,insects and other impurities present in the scum. After filtering we will be getting orange colour thick oil. From 3kg of scum about 1 litre scum oil was extracted. The free fatty acid of the oil was found to be high. 52
Diary waste scum Scum oil B. Preparation Of Scum biodiesel Transesterification is the process of reacting a triglyceride with alcohol in the presence of a catalyst to produce fatty acid esters and glycerol. It is difficult to produce ester from scum oil using alkaline catalyst (NaOH/KOH) because scum oil used is having high free fatty acid (FFA). Therefore, a two step transesterification process is chosen to convert the nonedible scum oil to its methyl ester. The first step acid catalyzed esterification reduces the FFA value of the oil to about 2%. The second step, alkaline catalyzed transesterfication process converts the products of the first step to its mono-esters and glycerol. In acid esterification, 1000 ml scum oil is heated to about 50 C; 150 ml methanol is added and stirred for a few minutes. With this mixture 2% H 2 SO 4 is also added and stirred at a constant rate with 65 C for one and half hour. After the reaction is over, the solution is allowed to settle for 24 hours in a separating funnel. The excess alcohol along with sulphuric acid and impurities floats at the top surface and is removed. The lower layer is separated for further processing (alkaline esterification). In alkaline catalyzed esterification, the products of the first step are again heated to about 65 to 70 C. With this mixture, 6.5 g NaOH dissolved in 150 ml methanol is added and stirred for 90 minutes. After the reaction is over, the solution is again allowed to settle for 24 hours. The glycerin settles at the bottom and esterified scum oil rises to the top. This esterified scum oil is separated and purified with warm water. After washing the final product is heated up to 105 C for 10 minutes.the esterified scum oil so prepared is referred as scum biodiesel. Finally 850ml of biodiesel and 150 ml of glycerin was obtained from 1litre of scum oil. The process flow chart of biodiesel extraction is as shown below. Figure1. Process Flow Chart C. Fuel Charecteristics of the Tested Fuel The important fuel properties of diesel and SOME are shown in table - 1. The determination of specific gravity, calorific value, viscosity, flash point, and fire point are carried out, as per the ASTM standard, by using a hydrometer, a Bomb calorimeter, a Kinematic viscometer, and Pensky-Martins closed cup apparatus. Table1: Fuel Properties of the Tested Fuels Characteristics Scum biodiesel Diesel Specific gravity 0.87 0.82 Kinematic Viscosity at 40 0 C(mm 2 /s) 3.9 2.54 Flash point ( C) 130 54 Density (kg/m 3 ) 870 820 Calorific value (kj/kg) 39940 43500 D. Experimental setup Figure 2: Schematic Diagram of the Experimental Set-up 53
Sl. No. Table 2: Test engine specification Engine Parameters 01 Engine Type Specifications TAF-1(Kirloskar, Four Stroke) 02 Number Of Cylinders Single Cylinder 03 Number Of Strokes Four-Stroke 04 Rated Power 4.4kw (6 Hp) @1500rpm 05 Bore 87.5mm 06 Stroke 110mm 07 Cubic Capacity 661.5cc 08 Compression Ratio 24:1 09 Rated Speed 1500 Rpm 10 Dynamometer Eddy Current Dynamometer 11 Type Of Cooling Air Cooling 12 Fuel Injection Pressure 200bar Figure 3: Load v/s Brake thermal efficiency Brake thermal efficiency is defined as the ratio between the brake power output and the energy of the oil/fuel combustion. Figure 3 shows that the variation of brake thermal efficiency (BTE) with load for different blends. It has been observed that the brake thermal efficiency of the blends is increasing with increase in applied load at compression ratio of 17.5:1 and injection pressure of 200 bar. It was happened due to reduction in heat loss and increase in power developed with increase in load. The maximum brake thermal efficiency at full load is 30.05% for B30, which is 2.73% higher than that of diesel. The brake thermal efficiency of standard diesel, B10, B20 and B100 are 30.02%, 28.49% and 27.43% respectively. By increasing the load of the engine, the brake thermal efficiency also increases for all the fuel types tested. The decrease in brake thermal efficiency for higher blends may be due to the combined effect of its lower heating value and increase in fuel consumption. 2. Brake specific fuel consumption (BSFC) : III. RESULTS AND DISCUSSION The experiments were conducted on a direct injection compression ignition engine for various loads and various blends of biodiesels. Analysis of performance parameters and emission characteristics like brake specific fuel consumption, brake thermal efficiency, hydrocarbon, carbon monoxide, nitrogen dioxide and exhaust gas temperatures are evaluated. A. Performance characteristics: 1. Brake thermal efficiency (BTE) : Figure 4: Load v/s Brake fuel consumption 54
The variation of specific fuel consumption with respect to load is presented in Figure 4 for different diesel biodiesel blends & neat diesel at compression ratio of 17.5:1 and injection pressure of 200 bar. As the load increases, BSFC decreases for all fuel blends. At full load, B10 shows the lowest fuel consumption and is 0.279 kg/kwh.the BSFC of the blends B20,B30 and B100 at full load is 0.295 kg/kwh,0.282 kg/kwh and 0.324 kg/kwh, whereas for diesel it is 0.303 kg/kwh. At higher percentage of blends, the BSFC increases. This may be due to fuel density, viscosity and heating value of the fuels. B10 has higher energy content than B20, B30 and B60, but lower than Diesel. Lesser values of BSFC are apparently desirable. 3. Exhaust gas temperature (EGT) Figure 5: Load v/s Exhaust gas temperature The variation of exhaust gas temperature with applied load for different blends is shown in Figure 5. The result indicates that the exhaust gas temperature decreases for different blends when compared to that of diesel at compression ratio of 17.5:1 and injection pressure of 200 bar. The highest temperature obtained is 385 C for standard diesel for full load, whereas the temperature is only 380 C, 340 C and 369 C for the blend B10, B20 and B30 respectively. The reason for the reduction in exhaust gas temperature is due to the lower calorific value of blended fuel as compared to the standard diesel and lesser temperature, at the end of compression. Lower exhaust loss may be a possible reason for higher performance. B. Engine Exhaust Results. 1. Hydrocarbon (HC) Figure 6: Load v/s Hydrocarbon Unburnt hydro carbons emission is the direct result of incomplete combustion. Figure 6 shows the variation of hydro carbon emission with load for different diesel biodiesel blends & neat diesel at compression ratio of 17.5:1 and injection pressure of 200 bar. The HC emission for all the blends and neat diesel goes on increases. The hydrocarbon emissions of various blends are higher at higher loads except the blend B20 and B100. B100 has least HC emission in all cases and in blends, B20 shows the lower HC emission compared to neat diesel at full load. A reason for the reduction of HC emissions with biodiesel is the oxygen content in the biodiesel molecule, which leads to more complete and cleaner combustion. 2. Oxides of Nitrogen (NOx): Figure 7 shows the variation of NO x emissions with load for different diesel biodiesel blends & neat diesel at compression ratio of 17.5:1 and injection pressure of 200 bar. The NO x emission for biodiesel and its blends is higher than that of standard diesel except B40 at lower loads. It is well known that the vegetable based fuel contains a small amount of nitrogen. Figure 7: Load v/s Oxides of Nitrogen 55
From the figure, it is obvious that for 50% load, NO x emission from the SOME blend B10, B20 is lesser than that of diesel. But for full load the NO x emission from the blend B10, B30 is higher than that of diesel. The other blends closely follow standard diesel. The reason for higher NO x emission for blends is due to the higher peak temperature. The NO x emission for diesel and blend B10, B20 for 50% load is 606 ppm, 608 ppm and 619 ppm respectively. 3. Carbon Monoxide (CO) Figure 8 shows that the variation of carbon monoxide emission of the blends and diesel for various loads at compression ratio of 17.5:1 and injection pressure of 200 bars. CO is a byproduct of combustion. The proportion of CO increases is due to rising temperature in the combustion chamber, physical and chemical properties of the fuel, air fuel ratio, lack of oxygen at high speed, and smaller amount of time available for complete combustion. At full load, B20 shows the lower CO emission and neat diesel shows sudden increase in CO emissions. Figure 8: Brake Power v/s Carbon monoxide The CO emission for all the blends and neat diesel goes on increases as load increases for both injection pressures. B30 shows the lower CO emission compared to neat diesel at all loads. A reason for the reduction of CO emissions with biodiesel is the oxygen content in the fuel, which enhances a complete combustion of fuel, thus reducing CO emissions. IV. CONCLUSION 1. The existing diesel engine performs satisfactorily on biodiesel fuel without any significant engine modifications. 2. Engine performance with biodiesel does not differ greatly from that of diesel fuel. The B30 shows good brake thermal efficiency in comparison with diesel. A little increase in fuel consumption is often encountered due to the lower calorific value of the biodiesel. 3. Most of the major exhaust pollutants such as HC, and CO are reduced with the use of blends of biodiesel as compared to neat diesel. 4. The major drawback of biodiesel is NOx emissions which increase diesel biodiesel fuel blends as compared to conventional diesel fuel and also difficulty in operation in cold temperature due to high cloud point. 5. Cost of biodiesel can reduced by using waste scum and can be further reduced by adopting mass production. 6. In terms of fuel properties and exhaust emission characteristics, SOME is regarded as a alternative fuel. V. REFERENCES [1] Knothe G, Karhl J, Van Gerpen J, editors. The biodiesel handbook. IL(USA): AOCS press Champaign; 2005 [2] P. Sivakumar, K. Anbarasu and S. Renganathan, Biodiesel production by alkali catalyzed transesterification of dairy waste scum, Fuel 90 (2011) 147 151. [3] N.L. Panwar, Hemant Y. Shrirame, N.S. Rathore, Sudhakar Jindal, A.K. Kurchania, Performance evaluation of a diesel engine fueled with methyl ester of castor seed oil, Applied Thermal Engineering, 30 (2010), pp. 245 249 [4] Avinas h Kumar Agarwal,K Rajamanoharan Experimental investigation of performance and emission of karanja oil and its blends in a single cylinder agriculture diesel engine Applied energy 86 (2009) 106-112. [5] A.S. Ramdhas, C. Muraleedharan, S. Jayaraj, Performance and emission evaluation of a diesel engine fuelled with methyl esters of rubber seed oil, Renewable Energy, 30 (2005), pp. 1789 1800 [6] Sukumar Puhan, n. vedaraman, Boppana V.B. Ram, G. Sankarnarayanan and K. Jeychandran, Mahua oil methyl ester as bio diesel-prearation and emission characterstics, biomass and Bioenergy, vol 28, pp. 87-93, 2005 [7] O.D.Hebbal, K.Vijayakumar Reddy, K. Rajagopal, Performance characteristics of a diesel engine with deccan hemp oil,fuel, 85 (2006), pp. 2187 2194 [8] Sharanappa Godiganur, C.H. Suryanarayana Murthy, and Rana Prathap Reddy, 6BTA 5.9 G-1 Cummins engine performance and emission tests usimg methyl ester mahua oil/diesel blends, Renewable energy, pp.2172-2177, 2009 56
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