Effect of Injection Timing on Performance and Emission of a Direct Injection Diesel Engine Fueled with Simarouba Biodiesel blend Srinath Pai 1, Akshath Shettigara 2, Dr. Abdul Sharief 3, Dr. Shiva kumar 4, Dr. Shreeprakash B 5 1 Associate Professor, Dept of M.E, Srinivas School of Engineering, Mangalore-575021, Karnataka, India 2 Student, Dept of M.E, Srinivas School of Engineering, Mangalore-575021, Karnataka, India 3 Professor and Principal, P.A.College of Engineering, Mangalore-574153, Karnataka, India 4 Associate Professor, Dept of M.E, MIT, Manipal-576104, Karnataka, India 5 Principal, S S E, Mukka,Mangalore-575021, Karnataka,India. Abstract Biodiesel is nothing but the alkyl monsters of fatty acids derived from vegetable oils or animal fats are attracting interest as an alternative fuel for diesel locomotives. The biodiesel fueled or blended diesel engines make less carbon monoxide, unburned hydrocarbons, and particulate emissions than diesel fueled engines. However, the properties of biodiesel (physical and chemical) are different from diesel, including a larger bulk modulus and a higher cetane number. These properties can be affected by oxidation of the fuel during storage. These changes can affect the timing of the combustion process and potentially cause increases in emissions of oxides of nitrogen (NOx). The performance and emission characteristics of diesel engines depend on many parameters. Precise control over the fuel injection process is one of the most important factors and plays a real important role in combustion to increase the engine performance with minimal exhaust emission. Injection timing and Injection pressure are the two important parameters which control the fuel injection process and enhance the more complete combustion. The objective of this study is to assess the effect of injection timing on biodiesel fueled diesel engine combustion and exhaust emissions. Keywords Biodiesel, Injection timing, Performance, Emission. I. INTRODUCTION The role of compression ignition engines has become famous for automobile applications due to its excellent fuel efficiency. On the other hand diesel engine emissions have faced stringent emission policies due to adverse effect on health issues of human organisms. In latest years research for biodiesel as an alternative fuel for diesel engines as well as to cut down the pollutant emissions, with aiming to overcome the depletion of fossil fuel and environmental degradation is under progress. Till date several alternative fuels like alcohols, vegetable oils, diesel and alcohol blend, biodiesel, diesel blend have been examined in detail. Among all the alternative fuels, few biodiesel those are biodegradable and non-toxic, have presented with equal performance as that of pure diesel with less emission other than NOx. Combustion, performance and emissions from engine purely depends on number of engine operating parameters like, injection swirl, injection pressure, compression ratio, injection rate and injection timing. Ignition delay and combustion characteristics of the engine and therefore the overall efficiency are significantly affected by injection pressure and injection timings. The NOx is produced at a great extent, due to the high local temperatures found in Diesel engines which are extremely dependent on the initial rise of heat release. In addition, soot production and oxidation are both dependent on the mixing rate and local flame temperatures. The injection velocity is one of the most influent parameters since it contains both the mixing process and the rate of heat release. The easy way to control NOx is either by retarding the fuel injection or by employing an extra device called turbo-charger. Retarding injection increases BSFC and deteriorates fuel economy, on the other hand decreases the NOx emission. The important engine parameters for NOx reduction are ignition delay, injection timing, inter-cooling, combustion chamber design, injection rate, and compression ratio. Among these study of injection timing is found considerably an easy method. According to the literature review [10], correct injection timing results in low emissions of CO, HC and nitrogen oxides (NOx). Especially NOx levels can be reduced with retarding injection timing with slight increase in brake specific fuel consumption. Advancing the timing results in increased cylinder pressures and higher peak flame temperatures which leads to a more complete burn of the fuel injected and the effect on emissions is significant. ISSN: 2231-5381 http://www.ijettjournal.org Page 312
II. LITERATURE REVIEWS An easy way to comply with A number of research papers and studies have been conducted to ascertain the effect injection timing on power, performance and fuel consumption and exhaust emissions of a diesel engine fuelled with biodiesel. Number of reviews has been taken below to endorse the present study. M. Mani et al[1], in their study on Influence of injection timing on performance, emission and combustion characteristics of a DI diesel engine running on waste plastic oil conducted their experimental study, they used a single cylinder, four stroke, direct injection diesel engine fueled waste plastic oil as a fuel. Tests were executed at four injection timings (23 o, 20 o, 17 o and 14 o BTDC). The standard injection timing was 23 o BTDC and the retarded injection timings were 20 o, 17 o and 14 o BTDC. At 14 o BTDC, resulted in decreased oxides of nitrogen, carbon monoxide and unburned hydrocarbon while the Brake thermal efficiency, carbon dioxide and smoke increased under all the test conditions. Saravanan et al[2], in their study on Combined effect of injection timing, EGR and injection pressure in reducing the NOx emission of a biodiesel blend conducted experimental study on a stationary engine. A swinging field electrical dynamometer was used to apply the load on the engine. Injection timing was changed by changing the thickness of shim. The spring tension of the injector needle with setting screw was varied to get the higher fuel injection pressure. In their study, an attempt was made to reduce the higher oxides of nitrogen (NOx) emission of a crude rice bran oil methyl ester (CRBME) blend through modification of combustion process by retarding fuel injection timing and exhaust gas recirculation at an increased fuel injection pressure. At modified condition, delay period and peak pressure of CRBME blend were lower than those at normal condition. The occurrence of maximum heat release rate retarded with a higher magnitude when compared with normal condition. As the result of combustion modification, NOx carbon monoxide emissions were reduced significantly with marginal increase in smoke density. Brake thermal efficiency and unburnt hydrocarbon emissions of the engine were increased due to the modification made. The investigation proved that the NOx emission of a biodiesel blend can be reduced with increase in the Brake thermal efficiency by modifying the combustion process, provided care to be taken lessen the smoke density. O. M. I. Nwafor [3], in his study on Effect of advanced injection timing on emission characteristics of a diesel engine running on biofuel conducted the experimental study on single cylinder, energy cell, air-cooled, high speed, indirect injection, four-stroke diesel engine. The energy cell consists of major and minor chambers which open into the main combustion chamber. The study was about to investigate the effect of advanced injection timing on emission characteristics of an unmodified diesel engine running on vegetable oil fuel. The test results show that the lowest carbon monoxide (CO) and hydrocarbon (HC) emissions were obtained in comparison on baseline diesel fuel with the advanced injection unit. The use of advanced injection also showed a slight increase in fuel consumption, exhaust temperatures rise and reduction in delay period. T. Balusamy et al[4], in their study on Effect of injection time and injection pressure on CI engine fuelled with methyl ester of thevetia peruviana seed oil conducted their experimental study, with an attempt to find the effect of injection timing and injection pressure on diesel engine fuelled with methyl ester of thevetia peruviana seed oil. A fully automated, single cylinder, constant speed, direct injection diesel engine was operated with the methyl ester of thevetia peruviana seed oil. Advancing the injection timing from the base diesel value and increasing the injector opening pressure have proved the increase in the Brake thermal efficiency with significant reduction in CO, HC and smoke emissions. Also, optimum results were found at the injection timing 27 o before top dead centre (BTDC) and injection pressure 225 bar combination. S.P. Wategavea et al[5], in their study on Effect of injection timing, injector opening pressure and nozzle geometry on the performance of a compression ignition engine operated on non-edible oil methyl esters from different sources has investigates the suitability of different non-ediblederived biodiesels such as cottonseed oil methyl ester (COME), honne oil methyl ester (HnOME) and honge oil methyl ester (HOME) to four-stroke, single-cylinder compression ignition (CI) engine. Engine tests were conducted to study the effect of fuel injection timing (IT), fuel injector opening pressure (IOP) and injector nozzle geometry on the performance, combustion and emission characteristics of COME, HnOME and HOME in the modified CI engine. IT was varied from 198 to 278 BTDC in steps of 48 BTDC, IOP was varied from 205 to 240 bar in steps of 10 bar. Nozzle injectors of three to five holes, each of 0.3mm size, were selected for the study. It was concluded that a retarded injection timing with increased IOP, results in overall better engine performance with increased Brake thermal efficiency and reduced hydrocarbon and carbon monoxide smoke emissions for the tested fuels. Srinath Pai et al[6], in their study on A Study on the Effect of Fuel Injection Pressure and Injection Timing on a Diesel Engine Performance and Emission conducted the experiment on a Kirloskar make TV1 model single cylinder, four stroke, water cooled 7 hp (5.2 kw) capacity diesel engine coupled to an eddy current dynamometer for loading ISSN: 2231-5381 http://www.ijettjournal.org Page 313
purpose. The experiment was carried out for the combination of injection pressures of 180 bar, 190 bar, 200 bar, 210 bar and 220 bar, and injection timings 15.5 o 20.5 o, 23.5 o and 25.5 o BTDC, at compression ratio 17.5:1, with a constant speed of 1500 rpm. It is clearly observed from the experimental investigations results that, an increase in the injection pressure with proper injection timing will significantly increases the engine performance with drastic reduction in emission. From the results best engine performance were found at the combination of injection pressure 220 bar and 25.5 o BTDC due to better combustion. G. Suresh et al[7], in their study on Effects of injection timing, injector opening pressure and nozzle geometry on the performance of cottonseed oil methyl ester-fuelled diesel engine conducted experiment using cottonseed oil methyl ester (COME) in a four-stroke, single-cylinder variable compression ratio diesel engine. Fuel injection timing varied from 198 o to 278 o before top dead centre (BTDC) in incremental steps of 48 o BTDC; fuel IOP varied from 210 to 240 bar in incremental steps of 10 bar. Fuel nozzle injectors with three, four and five holes, each of 0.3mm size, were selected for the work. The results suggested that with retarded injection timing of 198 o BTDC, increased IOP of 230 bar and a four-hole nozzle injector of 0.3mm size resulted in overall better engine performance with an increased Brake thermal efficiency and reduced HC,CO and smoke emission levels. Venkanna Krishnamurthy Belagur et al[8], in their study on Influence of static injection timing on combustion, emission and performance characteristics of DI diesel engine fuelled with honne oil methyl ester, investigated experimentally the combustion, exhaust emissions and performance characteristics of a direct injection (DI) diesel engine, when fuelled with neat diesel (ND), and honne oil methyl ester (HOME) is used in diesel engines. The static injection timing (SIT) is varied from 23 o crank angle (CA) (manufacturer s specified value) to 28 o CA. The combustion parameters of HOME improved as SIT increased. The Brake thermal efficiency (BTE) of HOME (SIT 27 28 o CA before top dead centre (BTDC)) is the highest. The emissions (smoke opacity (SO), CO, HC and NOx) of HOME (SIT 23 28 o CA BTDC), throughout the entire load range, are dropped compared to ND. The reductions in exhaust emissions (SIT 27 28 o CA BTDC) together with an increase in BTE made the HOME (SIT 27 28 o CA BTDC) a suitable alternative fuel for diesel fuel and proved in controlling the emission. Venkatraman.M et al[9], in their study, conducted the experiment on direct injection diesel engine coupled with electrical dynamometer, fueled with diesel and pungam methyl ester and their blends (PME10, PME20 and PME30). From the experimental investigation it is found that the combined increase of compression ratio, injection timing and injection pressure increases the BTHE and reduces BSFC while having lower emissions for PME20. The harmful pollutants such as HC, CO, are reduced in the pungam oil esters compared to diesel fuel. The maximum brake thermal efficiency is found to be PME20 (30.5%) in 27º BTDC and 240bar at compression ratio 19:1. The results show that at compression ratio19:1, higher injector opening pressure 240bar and advanced injection timing 27ºBTDC and PME20 can gives better performance and emission. III. EXPERIMENTAL SET UP AND TEST PROCEDURE Experiments were carried on a Kirloskar make TV1 model single cylinder, four stroke, water cooled 7 hp (5.2 kw) capacity diesel engine coupled to an eddy current dynamometer for loading purpose. The engine is provided with temperature sensors for the measurement of jacket water, calorimeter water, and calorimeter exhaust gas inlet and outlet temperature and also supplied with pressure sensors for the measurement of combustion gas pressure and fuel injection pressure. An encoder is set up and used for crank angle record. The engine is directly matched to an eddy current dynamometer. The Brake power produced by the engine is measured by the dynamometer. The engine specifications are made below. Table I Engine Specification SL. Engine Specification NO Parameters 1 Engine Type TV1(Kirloskar) 2 Number of Single cylinder cylinders 3 Number of strokes Four stroke 4 Rated power 5.2KW(7 HP) 5 Bore 87.5mm 6 Stroke 110mm 7 Compression 17.5:1 Ratio 8 Rated Speed 1500 rpm 9 Dynamometer Eddy current dynamometer 10 Type of cooling Water cooling 11 Injection Pressure 200 bar 12 Load Measurement Strain gauge load cell 13 Speed Rotary encoder Measurement 14 Temperature Indicator 15 Water Flow Measurement Digital, PT-100 type temperature sensor Rota meter ISSN: 2231-5381 http://www.ijettjournal.org Page 314
Fig. 1 Engine Test rig. The engine was supplied by the manufacturer with a combined rating of standard compression ratio (CR) of 17.5, injection timing 20.5 BTDC and injection pressure(ip) of 200 bar to run at a speed of 1500 rpm to obtain power 5.2KW(7 HP). The experiment was carried out for four different loading conditions (25%, 50%, 75% and 100%) and for three different injection timings 15.1 BTDC (Retarded), 20.5 BTDC (Rated) and 25.5 BTDC (Advanced) with simarouba biodiesel blend S20. Only S20 blend is used because S20 properties are almost matching with neat diesel as shown in table II and also the main objective of the experiment is to find the injection timing impact study using a suitable biodiesel. Under steady state conditions, for each injection timings and different loading conditions, for constant IP of 200 bar and CR 17.5 with S20 blend, performance parameters such as, Brake specific energy consumption and Brake thermal efficiency and emission parameters like CO, HC and NOx are measured and tabulated. Fig. 2 Brake thermal efficiency v/s load It was noted that about 2.15% of Brake thermal efficiency is improved for advanced injection timing 25.5 BTDC with compared to standard injection timing 20.5 BTDC at 75% load. At the same time some 1.16% of improved Brake thermal efficiency was observed for retarding injection timing 15.1 BTDC. This indicates that advancing injection timing improves the Brake thermal efficiency, and hence performance. Figure 3 as demonstrated shows the variation in Brake specific fuel consumption v/s load for injection timings 15.1, 20.5 and 25.5 BTDC with S20. It was observed that BSFC decreases with respect to increased load and for injection timings 25.5 and 20.5 BTDC it was much lower compared to injection timing 15.5 BTDC for S20 for all loads. This indicates that, as the injection timing retards fuel consumption gains. Brake specific fuel consumption v/s load Table III Properties of Diesel and Simarouba 840 868 845 Properties Diesel Simarouba S20 Density in kg/m 3 Cetane number 50 52 51 Calorific value 43000 39800 42360 in KJ/KgK Flash point 0 C 55 165 70 Viscosity at 400C in cst 2.7-5 4.8 3.4 IV. RESULTS AND DISCUSSIONS The results obtained from the experiments are represented in the form of graphs and are discussed as follows Fig. 3 Brake specific fuel consumption v/s load B. Emission Parameters CO v/s load A. Performance Parameters Brake thermal efficiency v/s load The data reported in Figure 2 shows the variation of Brake thermal efficiency versus load for injection timings 15.1, 20.5, 25.5 BTDC for S20. Fig. 4 CO v/s load ISSN: 2231-5381 http://www.ijettjournal.org Page 315
Figure 4 illustrated shows variation in CO emission v/s load, injection timings 15.1, 20.5, 25.5 BTDC for S20. Maximum CO emission is observed is for standard injection timing 25.5 at 25% to 75% load. For all injection timing for 65% to 100% load CO was found maximum. Minimum and drastic reduction in CO emission is observed for retarding injection timing 15.1 and continuously dropped till after 65% load, further little increase was found. For all injection timing initially and after 65% to 100% load CO was found maximum. This may be due to increase in load leads to decelerate the speed, finds deficiency in oxygen, results in increased CO formation. And initially CO is high may be due to idling to an over mixture. HC v/s load Fig. 5 HC v/s load Figure 5 shows variation in HC emission v/s load, for injection timings 15.1, 20.5 and 25.5 BTDC with S20. For 20.5 and 25.5 BTDC injection timings, HC emission was goes on increasing with load found maximum at full load. For 15.1 BTDC HC emission was found decreasing till 75% load and found maximum at full load. By retarding injection timing minimum HC emission is obtained. NOx v/s load Fig. 6 NOx v/s load Figure 6 shows variation in NOx emissions v/s load, for injection timings 15.1, 20.5 and 25.5 BTDC for S20. It is very clear that retarding injection timing gives lowest NO X emissions for all loads. As the injection timings increased in the order 15.1, 20.5 and 25.5 BTDC, NO X emissions also increased drastically, and found maximum for 75% load for injection timings 20.5 and 25.5 BTDC and approximately near to the maximum for injection timing15.1 BTDC. V. CONCLUSIONS The aim of this study was to investigate the impact of injection timing on the performance and exhaust emission characteristics of a diesel engine were experimentally investigated when the engine was fueled with biodiesel Simarouba biodiesel blend (S20). Based on the experimental outcome of this study, the following conclusions can be drawn: Analyses of the Injection timing variation have shown a significant effect on performance and emissions for S20 fueled diesel engine. Retarded injection timing from 20.5 to 15.1 BTDC results shows improved control over HC, CO and NOx emissions, with slight drop in BTE and BSFC at the same timing. This may be due to retarding Injection timing, cuts down the delay period reduces the peak pressure, which leads to drop in brake thermal efficiency. On the other hand engine operation become smooth, time available is more hence better mixing and oxygen availability is more resulting in better combustion. Even higher CN (For S20, CN=51) gives lower delay period and provides smoother engine performance, as most of the fuel burns completely, resulting in reduced emission. Advancing injection timing from 20.5 to25.5 BTDC for S20 fueled diesel engine showed that brake thermal efficiency increased, with a significant reduction in carbon monoxide emission and specific energy consumption compared with original injection timing. This may be due to increasing injection advance promotes injected fuel to vaporize easily and hence same amount of fuel supplied and burnt quickly. On the other hand NOx was found to be increased rapidly for all loads; may be due to as the delay period decreases, fasten the combustion process, availability of excess oxygen amount decreases and rate of pressure increase hence operating temperature of the engine increases, leads to higher NOx. Ultimately, it is concluded that the information obtained from this study is useful in the analysis of the injection timing impact in improving the performance of diesel engines along with their emission control as per government regulations. REFERENCES [1] M. Mani and G. Nagarajan, Influence of injection timing on performance, emission and combustion characteristics of a DI diesel engine running on waste plastic oil Energy, 2009 Vol. 34, No. 1617 1623. [2] S. Saravanan, G. Nagarajan Sampath, Combined effect of injection timing, EGR and injection pressure in reducing the NOx emission of a biodiesel blend International Journal of Sustainable Energy, 2014 Vol. 33, No. 2, 386 399. [3] O. M. I. Nwafor, Effect of advanced injection timing on emission characteristics of a diesel engine running on biofuel International Journal of Ambient Energy, 25:3, 115-122, DOI: 10.1080/01430750.2004.9674950. ISSN: 2231-5381 http://www.ijettjournal.org Page 316
[4] T. Balusamy & R. Marappan (2010) Effect of Injection Time and Injection Pressure on CI Engine Fuelled with Methyl Ester of Thevetia Peruviana Seed Oil, International Journal of Green Energy, 7:4, 397-409, DOI: 10.1080/15435075.2010.493811. [5] S.P. Wategave, M.S. Sawant, M.S. Tandale, G. Suresh, V.S. Yaliwal, N.R. Banapurmath & P.G. Tewari, Effect of injection timing, injector opening pressure and nozzle geometry on the performance of a compression ignition engine operated on non-edible oil methyl esters from different sources, International Journal of Sustainable Engineering,7:1,71-81, DOI:10.1080/19397038.2013.777134. [6] Srinath Pai, Abdul Sharief, Shiva Kumar and Sreeprakash B, Study of fuel injection pressure and injection timing effect on a diesel engine performance and emission, International Journal of Research in Science And Technology (IJRST) 2014, Vol. No. 4, Issue No. III, Jul-Sep, ISSN:2249-0604. [7] G. Suresh, H.C. Kamath & N.R. Banapurmath (2014) Effects of injection timing, injector opening pressure and nozzle geometry on the performance of cottonseed oil methyl ester-fuelled diesel engine, International Journal of Sustainable Engineering, 7:1, 82-92, DOI: 10.1080/19397038.2013.811703. [8] Venkanna Krishnamurthy Belagur & Venkataramana Reddy Chitimini (2012) Influence of static injection timing on combustion, emission and performance characteristics of DI diesel engine fuelled with honne oil methyl ester, International Journal of Ambient Energy, 33:2, 65-74, DOI: 10.1080/01430750.2011.636209. [9] Venkatraman.M and Devaradjane.G, Effect of Compression ratio, Injection Timing and Injection Pressure on a DI Diesel engine for better performance and emission fueled with diesel diesel biodiesel blends, International journal of applied engineering research, Dindigul volume 1, no 3, 2010, ISSN 09764259. [10] Srinath Pai, Dr. Abdul Sharief, Dr. Shiva Kumar, Dr. Ramachandra C.G & Dr. Sreeprakash B, Study Of Fuel Injection Pressure And Injection Timing Effect On A Diesel Engine Performance And Emission, International Journal of Research in Science And Technology (IJRST) ISSN: 2249 0604 Volume-4, Issue-3, July-Sept 2014, Page No. 71-80. ISSN: 2231-5381 http://www.ijettjournal.org Page 317