INVESTIGATIONS ON BIODIESEL FROM WASTE COOKING OIL AS DIESEL FUEL SUBSTITUTE

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1 INVESTIGATIONS ON BIODIESEL FROM WASTE COOKING OIL AS DIESEL FUEL SUBSTITUTE Jagannath Hirkude 1, 2*, Atul S. Padalkar 1 and Jisa Randeer 1 1 Padre Canceicao College of Engineering, , Goa, India, 2 Sinhgad College of Engineering, 41, Pune, India. ABSTRACT The waste cooking oil (WCO) as alternative fuel for diesel engines is the aim of this investigation. The high viscosity and poor volatility are the major limitations of waste cooking oil for their utilization in diesel engine. The most convenient method to use waste cooking oil as fuel is to convert it into biodiesel through transesterfication. The properties of waste cooking oil methyl ester such as viscosity, specific gravity, calorific value and flash point temperature were determined and compared with mineral diesel. This paper presents the results of investigations carried out on a brand new (Laxmi Industries, India made), single-cylinder, four-stroke, direct-injection, diesel engine operated with biodiesel of waste cooking oil blended with mineral diesel. Performance parameters like brake thermal efficiency, brake specific fuel consumption, exhaust gas temperature have been discussed. Present study is also carried out to investigate emission characteristics (particulate matter, SO x, NO x, CO 2, and CO) of blended biodiesel with mineral diesel in different composition. The performance parameters for different WCO biodiesel blends were found to be very close to diesel and the emission characteristics of engine improved significantly. It is possible to save by running the engine on B50 mode (Daily 6 hour s operation for 300 days).the experimental results proved that use of biodiesel (produced from waste cooking oil) is viable option to diesel in diesel engine. Keywords: Waste Cooking oil, Biodiesel, Diesel engine * Author for Correspondence jhirkude@yahoo.com Tel: , Fax: INTRODUCTION The used vegetable oil is classified as waste, while its potential as a liquid fuel through physical and chemical conversion remains highly interesting. Used vegetable oil is increasingly attracting interest because of its potential to be used as diesel substitutes known as bio-diesel. Direct synthesis via transesterification reaction of vegetable oils will yield bio-diesel. STM Journals All Rights Reserved 1

2 One of the advantages of these fuels is reduced exhaust gas emissions. Experience has shown that vegetable oil based fuels can significantly reduce exhaust gas emissions, including carbon monoxide (CO), carbon dioxide (CO 2 ), and particulate matter (PM) [1-2]. Because of their insignificant sulfur content, the sulfur dioxide (SO 2 ) emissions are low [3]. However, emissions of oxides of nitrogen (NOx) are in general, higher than those for mineral diesel fuel. Nye et al. [4] have collected waste fried oil composed of partially hydrogenated soybean oil and margarine and converted to biodiesel. Murayama et al. [5] have used methyl esterified WCO in both direct and indirect diesel engines. The particulate emissions from direct injection engine were found to be higher than indirect injection engine. Reed et al. [6] have tested biodiesel produced from WCO in a Denver public bus. The engine output power using biodiesel was comparable to that of diesel. The smoke opacity was reduced using biodiesel. Yu et al. [7] have carried out performance and emission analysis using WCO and observed similar engine performance and higher levels of CO, NO 2 and SO 2 compared with that of diesel. Currently, compared to petroleum-based diesel, the high cost of biodiesel is a major barrier to its commercialization. It is reported that approximately 70% 85% of the total biodiesel production cost arises from the cost of raw material. Use of low-cost feedstock such as WCO should help biodiesel competitive in price with petroleum diesel. Numerous studies have been conducted on biodiesel production and emission testing in the past two decades. Most of the current challenges are targeted to reduce its production cost, as the cost of biodiesel is still higher than its petro-diesel counterpart. This opens a golden opportunity for the use of waste cooking oil as its production feedstock. Everywhere in the world, there is an enormous amount of waste lipids generated from restaurants, food processing industries and fast food shops everyday. Reusing of these waste greases cannot only reduce the burden of the government in disposing the waste, but also lower the production cost of biodiesel significantly [8-12]. There is need to convert waste cooking oil from kitchen waste into biodiesel and transesterification is the most suitable process for this conversion. Present study is carried out to investigate performance and emission characteristics of blended waste fried oil biodiesel with mineral diesel in different compositions. The performance of diesel engine with mineral diesel has been considered as the baseline. MATERIALS AND METHODS The raw material (i.e. waste cooking oil) was collected from different hotels in Goa, a premier tourist destination in India. The used fried oil was filtered to remove food residues and solid precipitate by using double layer of cheesecloth in a funnel. In the transesterification it is important that the oil contains very minimal amounts of water STM Journals All Rights Reserved 2

3 because every molecule of water will destroy a molecule of catalyst. In order to avoid soap formation due to water the filtered fried oil was dried at 60 o C for 10 minutes using a microwave oven. To the preheated mixture of waste fried oil and methanol, NaOH was added. The amount of sodium hydroxide needed was 7.7 grams per liter by titration with waste fried oil. 200 ml of methanol is used against 1000 ml of waste fried palm oil. This solution was stirred at 600 rpm for 15 minutes and glycerin was allowed to settle for 24 hours. The biodiesel layer was separated from the glycerol layer in a separating funnel. Transesterification process followed to produce biodiesel from WCO is shown in figure 1. The process of biodiesel formation is shown in Figure 2. Fig. 1: Transesterification process STM Journals All Rights Reserved 3

4 Fig. 2: Process of biodiesel formation STM Journals All Rights Reserved 4

5 Fig. 3: Different blends of biodiesel and mineral diesel The fuels prepared for testing purpose were B50 (50% biodiesel + 50% mineral diesel), B70 (70% biodiesel + 30% mineral diesel), B90 (90% biodiesel + 10% mineral diesel), B100 (100% biodiesel) and mineral diesel. Figure 3 shows different blends of biodiesel and mineral diesel. The performance of a direct injection (DI) diesel engine is affected by the spray characteristics of the fuel emerging through the injector holes. Some researchers have reported that the most detrimental parameter in the use of vegetable oil as fuel is its higher viscosity [13]. The high viscosity is the cause of blockage of fuel lines and filters, high nozzle valve opening pressures and poor atomization [14]. The problems of high fuel viscosity can be overcome by using esters, blending and heating [15]. The properties of biodiesel produced are very important and should be taken into consideration before testing it in the engine [16-17]. Viscosity of WCO, WCO biodiesel and mineral diesel was determined using redwood viscometer. The viscosity of WCO biodiesel found very close to the diesel fuel, since transesterfication of WCO provided a significant reduction in viscosity, especially at low temperatures. The addition of WCO biodiesel slightly increased the viscosities of blends. Calorific value was estimated with help of bomb calorimeter and found lower than that of mineral diesel. The flash point temperature was found out by flash point apparatus and it is more than 93 o C which is minimum requirement for biodiesel based on ASTM D The properties of WCO, WCO biodiesel and mineral Diesel fuel are presented in Table 1. The properties of WCO biodiesel are in the acceptable ranges. STM Journals All Rights Reserved 5

6 Table 1: Properties Comparison Properties WCO Biodiesel Diesel Viscosity at 40 0 C (cst) Specific gravity Calorific Value (KJ/kg) Flash point 0 C The performance and exhaust emission tests were carried out on constant speed, direct injection single cylinder diesel engine. The experimental set consists of diesel engine, fuel measuring equipment, and exhaust gas analyser with digital temperature indicator. The engine specifications are given in Table 2. The engine was coupled to an electrical alternator connected with electric heaters of 0.5 kw each. Arrangement was made for break loading in the range of 0.5 kw to 4 kw. The specific fuel consumption was calculated by measuring the time taken for a fixed volume of fuel to flow into the engine. The torque was measured using swinging field electrical dynamometer. The engine speed (rpm) was measured by electronic digital counter. The performance parameters, break thermal efficiency and brake specific fuel consumption were calculated from measured data. The exhaust gas temperature was measured by using an electronic digital indicator with iron-constantan thermocouple. Emission analysis was carried for exhaust gas emissions particulate matter, CO2, SO2, NO2, and CO. Table 2: Engine Specification Make Laxmi Industries. Kolhapur (India) Rated Power 3. 8 kw Rated Speed 1500 rpm Number of cylinders 1 Bore X Stroke 80 X 110 mm Combustion Chamber Direct injection with bowl in piston Standard injection timing 27 0 BTDC Standard injection pressure 190 bar STM Journals All Rights Reserved 6

7 Fig. 4: Experimental Setup The fuels were tested in the engine running at 190 bar original fuel injection pressure. Engine experiments were conducted at constant speed of 1500 rpm at different loads (from 0.5 kw to 4 kw). The engine was coupled with a single phase, 220 V AC alternator. The alternator is used for loading the engine through a resistive load bank. The load bank consists of eight heaters with 0.5 kw capacities each. The schematic layout of the experimental setup for the present investigation is shown in Fig. 4. RESULTS AND DISCUSSION Brake Specific Fuel Consumption (BSFC) was found to increase with higher proportion of WCO biodiesel in the blend compared to diesel in the entire load range (Fig.5). Calorific value of WCO biodiesel is lower compared to that of diesel, therefore increasing proportion of WCO biodiesel in blend decreases the calorific value of the blend which results in increased BSFC of WCO biodiesel was lower than that with diesel. Estimations of the standard errors in reported data is provided in Table 4. Fig. 5: BSFC for diesel and different blends. Brake Thermal Efficiency (BTE) of WCO biodiesel in the blend compared to diesel in the entire load range (Fig 6). Brake thermal efficiency of B50 at rated output observed very close to diesel. It is only 3% less than that of mineral diesel. Oxygen present in the fuel molecules improves the combustion characteristics but higher viscosity and poor volatility of WCO biodiesel lead to their poor atomization and combustion characteristics. Therefore brake thermal efficiency was found to STM Journals All Rights Reserved 7

8 be lower for higher blend concentrations compared to that of mineral diesel. Brake thermal at part load conditions are very close with diesel. Fig. 6: BTE for diesel and different blends. The exhaust gas temperature with blends having higher percentage of WCO biodiesel observed higher compared to that of mineral diesel as WCO biodiesel contains constitutes of poor volatility, which burns during the late combustion phase (Fig 7). CO 2 emissions are reduced by 70% with B100 compared with mineral diesel. The emissions of CO increase with increase in load. Higher the load, richer fuel-air mixture is burned, and thus more CO emissions for WCO biodiesel are reduced by 19% with B50 and this reduction increases further with increase in concentration of biodiesel in the mixture. This is because additional oxygen content in biodiesel enhances complete combustion of the fuel and its higher cetane number. The higher the cetane number, the lower the probability of fuel-rich zones formation, usually related to carbon monoxide emissions. Particulate matter percentage reduces with increase in WCO biodiesel quantity in the blend. The least percentage of particulate matter observed with pure WCO biodiesel (B100). Reduction in Sulphur dioxide emission is found with increase in concentration of WCO biodiesel because of their insignificant sulfur content, the sulfur dioxide (SO2) emissions are low. NO x emission was increased with increase in WCO biodiesel concentration in the blend. This is because of the fact that the injection process is slightly advanced with biodiesel. Average WCO biodiesel emissions compared with mineral diesel is shown in the Table 3. Fig. 7: EGT for diesel and different blends STM Journals All Rights Reserved 8

9 Table 3: Average WCOME emissions compared with diesel Emission type B100 B90 B70 B50 Carbon Dioxide -70% - 65% -51% -35% Carbon Monoxide - 44% - 40% -33% -19% Particulate Matter - 45% -38% -33% - 21% NO X + 13% +11% +9% + 5 % SO X -100% -90% -70% -50% Table 4: Estimation of standard errors in the reported data Parameter Diesel B-50 B-70 B-90 B-100 BSFC (kg/kwh) Exhaust Gas Temperature( o C) Brake Thermal Efficiency (%) For the conversion of waste fried oil, methanol and sodium hydroxide are available at a rate of Rs 60/litre and Rs 250/litre respectively. The cost of waste fried oil considered was almost zero because it s treated as discarded waste, harmful to the environment. Biodiesel cost will depend greatly on methanol prices and economy can be achieved by varying the grade of methanol used. By-product of trans-esterification is industrial grade glycerin which has industrial use and can be sold with or without processing, as it is an important constituent in chemical, pharmaceutical and cosmetic industry. The cost of production of 1 liter biodiesel including cost of methanol, NaOH, collection, transportation, labour and processing is From performance analysis it is observed that for daily 6 hours operation for 300 days, it is possible to save by running the engine on B50 mode. CONCLUSIONS The prospectuses of waste cooking oil based fuel production are very attractive for conservation of energy for developing country like India. It has been seen that the discarded waste cooking oil has good potential as substitute for diesel fuel. Cost of conversion of biodiesel from waste cooking oil is very less ( per liter) compared with market price of diesel ( 35 per liter) even though it is heavily subsidized in India. In the present investigation a host of blends of biodiesel from waste cooking oil with mineral diesel oil were STM Journals All Rights Reserved 9

10 prepared and tested on a single cylinder constant speed diesel engine for its performance and emissions. The performance parameters for different WCO biodiesel blends found to be very close to diesel. Brake specific fuel consumption was found slightly higher for waste cooking oil biodiesel blends compared with mineral diesel. The brake thermal efficiency was found slightly lowers (3% at rated output) for waste WCO biodiesel blend compared with mineral diesel. From emission analysis it has been observed that WCO biodiesel can significantly reduce exhaust gas emissions, including carbon monoxide, carbon dioxide, sulpur dioxide and particulate matter. NOx emission was higher by 5% to 13% with increase in WCO biodiesel concentration. Authors like to conclude from this investigation, that biodiesel from WCO can be technically and economically feasible as alternate fuel for diesel. REFERENCES 1. Graboski M. S. et al. Progress in Energy and Combustion Science p. 2. Gonzalez M. E. et al. Environmental Monitoring and Assessment p. 3. Murayama T. INFORM (10) p. 4. Nye M. J. et al. Journal of the American Oil Chemists Society p. 5. Yasufumi Y. et al. Society of Automotive Engineers p. 6. Murayama T. et al. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering p. 7. Reed T. B. et al Biomass and Bioenergy p. 8. Yu C. W. et al. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering p. 9. Meng X. et al. Fuel Processing Technology (9) p. 10. Mittelbach M. et al. Journal of the American Oil Chemists Society p. 11. Lee K. T. et al. Journal of the American Oil Chemists Society p. 12. Mittelbach M. et al. Journal of the American Oil Chemists Society p. 13. Tahir A. R. et al. American Society of Agricultural Engineers p. 14. Nwafor O. M. I. et al. Journal of Applied Energy (4) p. 15. Romano S. American Society of Agricultural Engineers 1982, p. 16. Lang X. et al. Bioresource Technology p. 17. Canakci M. et al. Transactions of the ASAE (American Society of Agricultural Engineers) (6) p. STM Journals All Rights Reserved 10

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