KEY WORDS: SI engines, Inert Gas, Ignition timing, Argon gas. 1. INTRODUCTION

Proceedings of 3 rd International Conference on Recent Trends in Engineering & Technology (ICRTET 2014) Organized By: SNJB's Late Sau. K. B. Jain College Of Engineering, Chandwad ISBN No.: 978-93-5107-222-5, Date :28-30 March, 2014 Influence of ignition timing on performance, emission and combustion characteristics of a SI engine having added argon to intake mixture. T. Karthikeya Sharma * Research Scholar, Department of Mechanical Engineering, NIT Warangal, A.P, India. ABSTARCT- Environmental interests and limited resource of petroleum fuels have caused disquiet in the development of combustion and emission control research on (IC) engines. For a gasoline engine, spark ignition timing is a major parameter that affects the combustion and exhaust emissions. Dilution of the intake air of the Spark ignition engine with the inert gases is one of the emission control techniques like exhaust gas recirculation, water ignition in to combustion chamber and cyclic variability, varying ignition time without scarifying power output and/or thermal efficiency. This paper investigates the effects of ignition timing of a SI engine having added argon inert gas to dilute the intake air and to improve the performance and reduce the emissions mainly nitrogen oxides. The input variables of this study include the compression ratio, stroke length, and engine speed and argon concentration and ignition timing. Output parameters like thermal efficiency, volumetric efficiency, heat release rates, brake power, exhaust gas temperature and emissions of NO x, CO 2 and CO were studied in a SI engine, under variable argon concentrations. Results of this study showed that the addition of Argon gas to the intake air of the SI engine has significantly improved the emission characteristics and engine s performance within the range studied. KEY WORDS: SI engines, Inert Gas, Ignition timing, Argon gas. 1. INTRODUCTION International regulations ratified in recent years have imposed more stringent limits on pollutant emissions and fuel consumption in internal combustion engines. To comply with these regulations and reduce spark ignition NO x and soot emissions, several new combustion concepts have been developed. To comply with the emission regulations and to reduce NO x, CO and CO 2 emissions, and to improve engine performance several new combustion concepts have been developed. Some of the techniques deal with the recirculation of the exhaust gasses to improve the combustion process, usage of fuel blends, varying stroke length and compression ratio, after treatment devices like catalytic converters to convert NO X and CO in to non toxic gasses before they released in to atmosphere, injecting water in to the combustion chamber of the engine and varying ignition timing [1]. The performance of a SI engine is strongly affected by ignition timing. Ignition time also affects the thermal efficiency and emissions especially NO X emissions of SI engine. Proper ignition timing reduces the exhaust gas temperature which in turn reduces the NO X emissions. Early Combustion process, increased peak pressures and temperatures moved close to the TDC are the results of advanced ignition timing. Combustion at ideal crank angles can be achieved to some extent by advanced ignition timing. Hence advancing the ignition timing leads to improved the engine thermal efficiency. Proper time will be available for the oxidation of the charge during compression stroke. On the other hand, retarding the ignition timing decreases the pressure and temperature peaks during the combustion process because there is not enough time between the ignition timing and top dead * Corresponding author. E-mail address: karthikeya.sharma3@gmail.com Elsevier Publication 2014 246

T. Karthikeya Sharma center to complete the chemical reaction. Thus, large amounts of fuel burn after top dead center in the expansion stroke [2]. There are a number of NO x control technologies that have been developed for spark ignition Engines such as modified combustion to suppress NO x formation Low excess air operation Off-stoichiometric combustion Exhaust gas recirculation Reduce NO x to molecular nitrogen through controls (also known as exhaust gas treatment) Selective Non-Catalytic Reduction (SNCR) Selective Catalytic Reduction (SCR) Dry Sorption The power output and/or thermal efficiency have to be sacrificed with these methods. The promising approach to reduce NO X emissions form a spark ignition engine is to replace a small percentage of N2 in the intake air with an inert gas. It was found that the CO 2 of the emissions in the EGR technique has only a small effect on the emissions as it s having low specific heat value [3]. In this study Argon gas having a specific ratio of 1.667 at room temperature is used to compensate the low specific heat ratio of the CO 2. It was ensured that the added gas mixture had a specific heat capacity equal to that of the N 2 being replaced, why because as the specific heat ratio of the mixture increases the cylinder peak pressure increases and it occurs at earlier crank angles [4]. Therefore, it is the main destine of the present work to probe in details the effects varying ignition timing on the test engine having argon gas as a diluting gas on its performance and emissions. The present study was carried out on a single cylinder four stroke spark ignition engine The tendency of the present work included the investigation of the thermodynamics properties of the intake gas mixture when argon is added, the effects of adding argon on the performance of the engine and the exhaust emissions, and finally the heat release rate analyses under varying ignition timings. 2. EXPERIMENTAL SET-UP A four stroke engine with modified intake to admit the preset concentrations of argon and air (O 2 + N 2 ) was used. This section will present the experimental apparatus and the experimental procedure. 2.1. Engine experimental apparatus: A single cylinder, four stroke, and water cooled constant speed port fuel injection Spark ignition engine was used for experiments. Engine performance and emissions at various ignition timings was detected by a new Electronic Ignition Control Unit (EICU). Newly developed electronic ignition control unit was used to control the ignition timing. Various signal values obtained from the literature are fed to the ignition control unit for our test engine according to vacuum values at test points. Tests were conducted by altering the ignition timings on both sides of the original value i.e. 22 0 CA BTDC. Five different sets of ignition advance values were used in he performance tests. A step of 2 0 CA was considered on both sides. Set of ignition timings considered for tests are 18 0, 20 0, 22 0, 24 0, 26 0. The ignition timings 18 0, 20 0 represents the delayed ignition timings and 24 0, 26 0 represents the advanced ignition timings. Tests were conducted using these Ignition timings. proper care was taken to record the data correctly while the test are being conducted. Argon up to 15% of the intake air admission capable test rig has been designed and built. The test rig built has the capability to vary the argon concentration by keeping the oxygen concentration in the intake air as constant (i.e. 21% by volume), this was achieved by adding one oxygen cylinder to the system. The added argon will replace the nitrogen gas concentration in the intake air. SmartTrak 100 digital flow meter has been used to measure to the volume flow rate of the argon gas acquiesced to the engine. XFM Stainless steel Multi- dro capability RS-232/RS-485, profibus DP digital thermal mass flow meter has been used to measure the air flow rate. WITT MM-2K pressure fluctuation free gas mixture has been used to mix the argon and oxygen in required concentrations. Silicon chip fuel mixture display system has been used to control the air fuel ratio, it consists of exhaust gas oxygen (EGO) sensor mounted in the exhaust system to continuously monitor air-fuel ratios and generate corresponding output voltages. This information is then fed to the engine management computer (EMC) which continuously adjusts the mixture to provide optimum power and economy, consistent with low exhaust emissions. Brief technical data are shown in Table 1.Fig. 1 shows the schematic diagram of the experimental system. Elsevier Publication 2014 247

Table 1. Engine Specifications Number of cylinders 1 Bore 95.12 mm Stroke 71.5 mm Displacement volume 1297 cc Maximum speed 3500 rpm Max. Cylinder pressure 130 bars Compression ratio 8:1 Constant Ignition timing, deg. BTDC 22 Cooling system Water cooled Valve arrangement Two vertical over head valves Max power 6.76 kw @ 3500 rpm Max torque 18.7 N m @ 2600 rpm Fig.1. Schematic of the experimental set-up. Ignition timing constant at 22 0 BTDC, carburetor position at full throttle opening, fuel used is gasoline with octane number 95. A Kistler model 6005 Quartz high pressure engine combustion sensor has been used to measure the combustion pressure inside the engine cylinder. A dual mode charge amplifier was used to amplify the signal from the engine combustion sensor. The degree marker shaper amplifier measured and displayed angular crank shaft location. A PicoScope 4423 oscilloscope, 2000A current clamp, 60A current clamp four channels high-speed digital oscilloscope has been used to measure and store various signals such as those from the crankshaft position sensor or the camshaft Hall sensor and pressure. The amplified signals from the pressure sensor and degree marker were fed to the oscilloscope. PicoScope is fast enough and accurate enough to look at the electrical signals on CAN bus, LIN bus and the new FlexRay interface to allow the fast measurement, storing and analysis of high-speed phenomena. The input signal could be stored at the rate of up to 1500 MHz. Up to five sets of the stored waveform could be saved. The saved waveform was retained then transferred to a PC for further computation. Ecom EN2 Electro Chemical gas analyzers having 4 Electrochemical Sensors, sensor Options: O2, CO, NO & NO2, 1ft Inconel Probe (up to 1832F/1000C), CO purge pump to prevent oversaturation, Peltier cooler sample conditioner, peristaltic pump for automatic moisture removal, flue gas, ambient, & sensor temperature sensors, CO2, Efficiency, Losses, Excess Air, & O2 Correction Calculations were used for measuring NO x, CO 2, and CO and for the exhaust gas analyses. Murphy TDX6 Temperature Scanner/Pyrometer Swichgage with 6 channels, Type J or K Thermocouples Grounded or Ungrounded acceptability, and having a J-type accuracy from 50-150 F (10-66 C) +3 F(+2 C), from 150-1200 F (66-649 C) ±1.0% of reading has been used to measure the temperatures of inlet cooling water, air inlet, outlet cooling water, exhaust and oil sump using Type J thermocouples. 2.2. Experimental procedure: The present work endeavors at studying the consequences of ignition time and diluting inlet air with argon gas in the test spark ignition engine. The experimental procedure was planned and may be divided into four catagerious. (a)experiments on Spark ignition engine by varying ignition timing from 18 0 CA BTDC to 26 0 CA BTDA and running on dilute intake air with argon at a constant and running on diluted intake air with argon at a constant and engine speed of 2100 rpm. (b) ) Experiments on Spark ignition engine varying load from 5Nm to 20Nm with a 5Nm step, and running on diluted intake air with argon at an ignition time of 22 0 CA BTDC. During the first set of tests, the engine has been running on mixture of oxygen, argon and nitrogen on preset concentrations. Keeping the oxygen always at 21% the ratios of argon to be from 0% to 15% have been selected in the mixture. For the time of first test with an ignition time of 18 0 CA BTDC the engine speed has been kept constant at 2100 rpm and the load at 20Nm. The argon amount is then increased at 5% step. Various output parameters like thermal efficiency, brake mean effective pressure, volumetric efficiency; specific fuel consumption, heat release rates, brake power, exhaust gas temperature and emissions of NO x, CO 2 and CO have been measured and recorded. The tests were repeated taking 20 0 CA BTDC to 26 0 CA BTDC as the ignition timings following the same procedure as previous. During the second set of tests, the engine has been running on mixture of oxygen, argon and nitrogen on preset concentrations. Keeping the oxygen always at 21% the ratios of argon to be from 0% to 15% have been selected in the mixture. For the time of first test with a load of 5Nm the engine speed has been kept constant at 2100rpm and the ignition time as 22 0 CA BTDC. The argon amount is then increased at 5% step. Various output Elsevier Publication 2014 248

T. Karthikeya Sharma parameters like thermal efficiency, brake mean effective pressure, volumetric efficiency; specific fuel consumption, heat release rates, brake power, exhaust gas temperature and emissions of NO x, CO 2 and CO have been measured and recorded. The tests were repeated at 2100rpm, 2300rpm and 2500rpm by following the same procedure as previous. 2.3. Experimental error analysis Table 2 Specification Maximum error value Relative error Engine speed 0.01 rev/s 0.28% Engine torque 0.08 Nm Brake power 3.26% Brake specific fuel consumption 2.42% Exhaust gas temperature 0.1 0 C 0.1% Exhaust gas concentration(no X ) 0.01ppm Exhaust gas concentration(co, CO 2, O 2 ) 0.1ppm Flow rate of air 1.02 x10-4 m 3 /s 1% Flow rate of argon 4.3% Fuel flow rate 1 cm 3 Timer ( Time Measurement) 10ms 0.7% 3. RESULTS AND DISCUSSIONS A long term experimental study has been conducted on a single cylinder, four stroke, water cooled spark ignition engine with argon inert gas in intake mixture. Thermodynamic effects of adding the argon to the intake air of the engine at varying ignition timing and loads have been studied. The amount of oxygen gas has been kept constant at 21% by volume. The engine parameters have been kept at the values mentioned above. The results of the both the case were compared. 3.1 Exhaust Gas Temperature: A long term experimental study has been conducted on a single cylinder, four stroke, water cooled spark ignition engine with argon inert gas in intake mixture. Thermodynamic effects of adding the argon to the intake air of the engine at varying ignition timing and loads have been studied. The amount of oxygen gas has been kept constant at 21% by volume. The engine parameters have been kept at the values mentioned above. The results of the both the case were compared. 3.1 Exhaust Gas Temperature: The exhaust gas temperature variation under different ignition timing and loads with the argon addition ratio may be seen in Figs. 2 and 3 respectively. Exhaust gas temperature is an indication of combustion occurring in the cylinder. Fig 2. Exhaust gas temperature variation at different Ignition timings and argon concentrations at constant engine load of 20Nm. Fig 3.Exhaust gas temperature at different Engine loads and argon concentrations at constant ignition timing of 22 0 CA BTDC Elsevier Publication 2014 249

The decrease in exhaust gas temperature with increase in argon concentration may be seen from the Figs 2 and 3. The decrease in exhaust gas temperature with increase in argon concentration in both the constant load and constant ignition timing is because of the fast diminishing of the combustion temperature during the expansion stroke. With increase in argon percentage the drop rate of combustion temperature during expansion stroke will be more. Fig. 2 manifests a decrease in exhaust temperatures with increase in ignition timing (i.e. advancing ignition timing). Post reaction phenomena increases the exhaust gas temperature under retarded ignition timings, where as advancing the ignition timing shows a decrease in the exhaust temperature. Advancing ignition timing increases the peak pressures and temperatures occur at TDC as the combustion takes place at TDC this result in increasing in NO X emissions [5]. Fig 3. Shows the increase in exhaust gas temperature with increase in load on the engine. This is because as the load increases more fuel needs to be burnt to maintain the constant speed this results in increase in the exhaust gas temperature. 3.2 Brake specific fuel consumption (Bsfc): Figs.4 and 5 gives the variation of the Bsfc with increase in argon percentage for both the constant load and constant ignition timings tests. The decrease in Bsfc can be observed from the figures with the increase in argon concentration. The increase in the brake mean effective pressure (bmep) with adding more argon increases the brake power output of the engine resulting in reduction of bsfc of the engine. A maximum drop of 15g/kWh at 26 0 CA BTDC and 33g/kWh of Bsfc at 20Nm load are observed with an increase of argon concentration from 0% to 15%. Fig 4. Brake specific fuel consumption variation at different Ignition timings and argon concentrations at constant load of 20Nm When the ignition timing was retarded by 4 0 CA BTDC compared to original ignition timing (22 0 CA BTDC), Bsfc increased by 6.3% for 0% Ar and 7.36% for 15% Ar. Combustion at ideal crank angles can be achieved to some extent by advanced ignition timing. Hence advancing the ignition timing leads to improved the engine thermal efficiency. Proper time will be available for the oxidation of the charge during compression stroke. So fuel consumption per unit power output will decrease i.e Bsfc decreases. the other hand, retarding the ignition timing decreases the pressure and temperature peaks during the combustion process because there is not enough time between the ignition timing and top dead center to complete the chemical reaction. Thus, large amounts of fuel burn after top dead center in the expansion stroke. So Bsfc increases with retarded ignition timings. Fig 5.Brake specific fuel consumption at different Engine loads and argon concentrations at constant ignition timing of 22 0 CA BTDC Bsfc decreased about 6.45% for 0% Ar and 7.7% for 15% Ar, as the engine load increased from 5 Nm to 20 Nm constant loads respectively. This decrease in Bsfc could be explained by the fact that; as the engine load increases, of the rate of increasing brake power is much more than that of the fuel consumption. Elsevier Publication 2014 250

T. Karthikeya Sharma 3.3 Brake thermal efficiency (BTE): The Brake thermal efficiency variation with ignition timing and load with the argon addition ratio may be seen in Figs. 6 and 7 respectively. Fig 6. Brake thermal efficiency variation at different Ignition timings and argon concentrations at constant load of 20Nm. Increase in Brake thermal efficiency can be observed from the figures in both the constant load and constant ignition timing as the argon concentration increases. The increase in argon concentration decreases the brake specific fuel consumption delivering constant power output this is the reason for increase in brake thermal efficiency. BTE indicates the how efficiently the chemical energy of the fuel is converted in to mechanical work by the engine. BTE results are presented in Figs. 6 and 7 for different engine loads and ignition timings, respectively. The 15% Ar at 20 Nm with original ignition timing produced the highest BTE as 49.2%. Fig. 6 shows the variations of the BTE with different argon concentrations for different ignition timings at 20 Nm constant loads. The best results in terms of BTE were obtained at original ignition timing. Retarded or advanced ignition timing diminished BTE values Fig 7.Brake thermal efficiency at different Engine loads and argon concentrations at constant ignition timing of 22 0 CA BTDC For example, when the ignition timing was retarded and advanced 4 0 CA compared to original ignition timing, BTE decreased by 20.4% and 6.3% for 18 0 CA BTDC and 26 0 CA BTDC at 20 Nm load, respectively. Increase in brake thermal efficiency can be observed form fig 7. as the load increases this is because of reduced Bsfc at increased loads. 3.4 CO Emission: Figs. 8 and 9 depict the carbon monoxide levels in the exhaust gas for both constant load and ignition time tests at various argon concentrations. It can be seen from the figures that introducing argon gas in the intake has resulted in increase of CO from 0.31 to 0.38 g/kwh when argon is increased from 0% to 15% at 22 0 CA BTDC. This increase may be because of the unavailability of the oxygen during combustion with the addition of argon. One more reason may be because of the faster drop in combustion temperature during exhaust stroke make the formation of CO 2 from CO. Increase in argon gas concentration reduces the exhaust gas temperature, at lower exhaust temperatures Elsevier Publication 2014 251

CO cant not react with O 2 to form CO 2. From fig 8.at original ignition timing, while CO emission was measured as 0.46 g/kwh with 15% Ar at 20 Nm load, it was 0.72 g/kwh at 5 Nm. When the ignition timing advanced, the level of CO emission increased. Advancing the ignition timing 4 0 CA (from 22 0 to 26 0 CA BTDC) caused the CO emission increased by 9.5% for 15% Ar at 20 Nm load. The increase in fuel consumption may be the reason for increase in CO emissions. However, retarding the ignition timing 4 0 CA (from 22 0 to 18 0 CA BTDC) caused 18.3% decrease in the CO emission under the same test condition mentioned above. Fig 8. CO emissions at different Ignition timings and argon concentrations at constant engine speed of 2100rpm From fig.9.co emission reduced steadily when the engine load increased in the engine. When the engine load increased, combustion temperature increased as shown in Fig.3. Therefore, CO emissions started to decrease [6]. The results obtained in this study confirmed this statement. Fig 9. CO emissions at different Engine loads and argon concentrations at constant ignition timing of 22 0 CA BTDC 3.5. Carbon dioxide (CO 2 ) emissions: The variation in the emission of Carbon Dioxide against the argon added percentage at constant load and constant ignition timing is shown in Figs 10 and 11 respectively. With the addition of argon the CO 2 emissions increases first during the argon concentration between 3-6% and then in decreases. The increase in CO 2 emissions in the early concentrations of argon may be because of the increase in air fuel ratio and availability of more oxygen, but as the argon concentration increases further exhaust oxygen reduces so the CO 2 emissions decreases.co 2 is a normal product of combustion. Ideally, combustion of a hydrocarbon fuel should produce only CO 2 and water (H 2 O).The CO 2 concentrations behaved differently when compared with the CO concentrations because of improving combustion sufficient temperatures attained for the conversion of CO to CO 2 by reacting with O 2 [7]. Fig. 10 CO 2 emissions at different Ignition timings and argon concentrations at constant engine load of 20Nm. Elsevier Publication 2014 252

T. Karthikeya Sharma Fig 11. CO2 emissions at different Engine loads and argon concentrations at constant ignition timing of 22 0 CA BTDC Maximum CO 2 was observed to be 27.1 g/kwh at 5% Ar and at 22 0 CA BTDC for the 20 Nm engine load. CO2 emissions decreased with the advancing ignition timing, as shown in Fig. 10, for the all fuel mixtures. When the ignition timing was changed from 18 0 to 26 0 CA BTDC, the level of CO 2 emission was decreased by 9.5% at 26 0 CA BTDC and at 20 Nm constant loads. This increase may be associated with the increase in the fuel consumption. From Fig 8. it can be seen the decrease in CO 2 emissions with increase in load on the engine. The reason behind it may be because of low temperature combustion which doesn t facilitate the conversion of CO to CO 2 by reacting with O 2 under high temperatures. 3.6. NO X emissions: One of the most critical emissions from SI engines is NOx emissions. The oxides of nitrogen in the exhaust emissions contain nitric oxide (NO) and nitrogen dioxide (NO2). The formation of NO X is highly dependent on the in-cylinder temperature, oxygen concentration and residence time for the reaction to take place [8]. Figs.12 and 13 indicates that the NO X levels under constant ignition timing and at constant load, point to remember that in both the case argon gas was introduced in to intake air mixture at different concentrations. The reason for decreased NO X emissions with the addition of argon in both the cases are because of the addition of argon reduced the concentration of nitrogen in the intake air. The addition of argon replaced the N 2 gas by a mole fraction of about 19% while the O2 has been kept constant. Reducing the N 2 mole fraction by 19% reduced the emission of NO in the exhaust gases by 55% means there are other factors that play an important role in the process. The other reason for the reduction of NO in the exhaust gases is increasing the air/fuel ratio as it plays important role in this reduction as has been shown before [9]. Fig. 12 indicates the variations of NO X emissions for different Ar concentrations under different ignition timing at the 20 Nm constant load. ig 12. NOX emissions at different Ignition timings and argon concentrations at constant engine load of 20Nm. When the ignition timing was retarded, some decrease was observed in the NO X emissions. When the ignition timing was retarded 4 0 CA BTDC compared to original ignition timing, NO X emissions decreased by 25.6% at 10% Ar. Retarding the ignition timing decreases the peak cylinder pressure because more fuel burns after TDC. Lower peak Elsevier Publication 2014 253

cylinder pressures result in lower peak temperatures. As a consequence, the NO X concentration starts to diminish [10]. The obtained exhaust gas temperatures, shown in Figs. 2 and 3, confirmed this statement. The changes on the NOx emissions at different engine load are shown in Fig. 13. NO X concentration generally increased with increasing engine load. The experimental results indicated that NO X values for 15% Ar were lower than the others. Minimum NO X was observed to be 0.5 g/kwh for 15% Ar under 5Nm load. Fig 13. NO X emissions at different Engine loads and argon concentrations at constant ignition timing of 22 0 CA BTDC 4. CONCLUSION In this study, the performance and exhaust emissions of a single cylinder, Spark ignition engine were measured, argon inert gas in different proportions as a diluting gas was used at the different engine loads and ignition timings. The results showed that the ignition timing play an important role in the combustion process. From the current study, the following conclusions can be drawn. In terms of ignition timing, the test results demonstrated that; with advancing the ignition timing, CO and NO X emissions increased while and CO 2 emissions decreased. Increase in CO emissions has been observed because of advanced ignition timing, because of the increase in fuel consumption. The decrease in CO 2 is observed at increased loads reason behind it may be because of low temperature combustion which doesn t facilitate the conversion of CO to CO 2 by reacting with O 2 under high temperatures. Increases the NO X emissions (at high temperatures N 2 in air reacts with O 2 to form NO X ). The increase in NO X emissions with advanced ignition is because of the increased peak temperatures before TDC facilitating the reaction between O 2 in air with N 2 at high temperatures. The original ignition timing gave the best results for Bsfc and BTE compared to the other ignition timings [11]. As the argon concentration increases the Bsfc decreases. Decrease in volumetric has been observed with increase in argon percentage. Increasing the argon concentration resulted in the decrease of the emission index of nitrogen oxide (NO), and carbon dioxide (CO2). Increase in CO emissions has been observed with increase in argon addition to intake air. Exhaust gas temperature decreases with increase in argon concentration this improves the exergy of the system. References: [1]. Karthikeya Sharma T, Amba Prasad Rao G, Combustion Analysis of Ethanol in An HCCI Engine. Trend in Mecha Eng & Tech 2013;3;1-9. [2]. Nox emission from a spark ignition engine Using 30% iso-butanol±gasoline blend: part 2 Ignition timing F. N. Alasfour [3]. Cheng WK, Wong VM, Gao F. Heat Transfer measurement comparisons in insulated and non- insulated diesel engines. SAE Transactions 1989;890570. [4]. Hany A. Moneib. NOx emission control in SI engine by adding argon inert gas to intake mixture. Energ Conserv Manage 2009; 2699-2708. [5] Türköz, Necati, et al. "Experimental investigation of the effect of E85 on engine performance and emissions under various ignition timings." Fuel (2013). [6] Abdel-Rahman AA. On the emissions from internal-combustion engines. International Journal of Energy Research 2002;22(6):483-513. [7] Williams PT, Williams EA. Interaction of plastics in mixed plastics pyrolysis. Journal of Energy and Fuels 1990;13:188-96. [8]. Heywood JB. Internal combustion engines. USA: Mc-Graw Hill; 1984. [9]. Borat O, Balci M, Surmen A. Internal combustion engines. Turkey: Gazi University Publishing; 2000 [in Turkish]. [10]. Chan SH. Performance and emissions characteristics of a partially insulated gasoline engine. Int J Therm Sci 2001;40:255-61. [11] Sayin C, Ertunc HM, Hosoz M, Kilicaslan I, Canakci M. Performance and exhaust emissions of a gasoline engine using artificial neural network. Applied Thermal Engineering 2007;27:46-54. Elsevier Publication 2014 254