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Öğe Application of energy and exergy analyses to a ci engine using biodiesel fuel(Association for Scientific Research, 2011) Sekmen, P.; Yilbasi, Z.In recent years, exergy analysis method has been widely used in the design, simulation and performance assessment of various types of engines for identifying losses and efficiencies. In this study, the first and second Laws of thermodynamics are employed to analyze the quantity and quality of energy in a four-cylinder, direct injection diesel engine using petroleum diesel fuel and biodiesel fuel. The experimental data were collected using steady-state tests which enable accurate measurements of air, fuel and cooling water flow rates, engine load, and all the relevant temperatures. Balances of energy and exergy rates for the engine were determined and then various performance parameters and energy and exergy efficiencies were calculated for each fuel operation and compared with each other. The results of tested biodiesel offer similar energetic performance as petroleum diesel fuel. In addition to this, the exergetic performance parameters usually follow similar trends according to the energetic performance parameters. © Association for Scientific Research.Öğe Biodiesel production from waste melon seeds and using it as alternative fuel in direct injection diesel engine(Elsevier Sci Ltd, 2010) Aktas, A.; Sekmen, Y.; Sekmen, P.Melon seeds containing similar to 30% oil are wasted after the fruit is consumed. The chemical and physical properties of melon seed oil are very similar to vegetable oils used as biodiesel fuel. There are no studies regarding the use of melon seed oil or its esters as fuel in literature. In this study, oil was extracted from waste melon seeds and transformed to melon seed oil methyl ester (MSOME) by transesterification process. This fuel is used in a four stroke single cylinder direct injection diesel engine, and its effects on performance and emissions were investigated for various engine speeds at full load. In addition, diesel fuel no. 2 and soy bean oil methyl ester (SOME) is used as fuel under the same operating conditions for comparison purposes. According to the experiment results, specific fuel consumption is found to be more in both biodiesel fuels compared to diesel fuel, and the engine torque is 1-6% lower with MSOME and 3-5% with SOME compared to diesel fuel. Exhaust gas temperature is lower with MSOME and SOME than with diesel fuel. Furthermore, it is found that CO and HC emissions and smoke density are generally lower in both biodiesel fuels. However, NOx emission is slightly higher for SOME and MSOME than that for diesel fuel.Öğe Investigation of the dynamic performance of an Electro Mechanical Valve (EMV) system at different lifting operations and determination of the support limits of an internal combustion engine(2013) Birgül, N.; Sekmen, P.Electro Mechanical Valve (EMV) actuators are currently being developed by many researchers and engine and automotive component manufacturers. These actuators can potentially improve engine performance via flexibility in valves timings at all engine operating conditions. Unlike conventional camshaft driven systems, EMV system affords valve timings that are fully independent of crankshaft position. Thus the electromechanical valve train technology allows controlled opening and closing events for intake and exhausts valves and offers a big potential to minimize the fuel consumption and the emissions. The purpose of this study is to investigate dynamic performance of an EMV system, which has 12-volt supply voltage, at different lifting valve operations and thus to determine the support limits of an internal combustion engine.Öğe Mathematical modeling of a SI engine cycle with actual air-fuel cycle analyses(Association for Scientific Research, 2007) Sekmen, P.; Sekmen, Y.The performance of an engine whose basic design parameters are known can be predicted with the assistance of simulation programs into the less time, cost and near value of actual. However, inadequate areas of the current model can guide future research because the effects of design variables on engine performance can be determined before. In this study, thermodynamic cycle and performance analyses were simulated for various engine speeds (1800, 2400 ve 3600 1/min) and various excess air coefficients (EAC) (0.95-1.05) to crank shaft angle (CA) with 1 degree increment at full load and 8:1 constant compression ratio (CR) of a SI engine with four stroke, single cylinder and natural aspirated. Brake mean effective pressure, power, thermal efficiency, specific fuel consumption (sfc), etc engine performance parameters were calculated; the values of peak cylinder pressures and temperatures and positions of them were determined by the present program. Variations of these parameters with crank angle, engine speed and excess air coefficient were presented graphically. The calculated results show good agreement with literature. Simulation program is usable to set for varies load, compression ratios, and engine sizes. © Association for Scientific Research.
