Assessment of Total Efficiency in Spark Ignition Adiabatic Engines

Assessment of Total Efficiency in Spark Ignition Adiabatic Engines

The paper presents the effect of ceramic coating on working parameters, mainly on heat balance and overall performance, on all surfaces of the combustion chamber of the four-stroke engine SI. Three engine cases were considered: the standard without ceramic coating, the completely adiabatic combustion chamber and the engine with different ceramic coating thicknesses. The mathematical modeling of heat transfer from the cylinder gas to the cooling medium was realized by considering the adiabatic or semi-adiabatic engine. This model takes into account the variable convection coefficient based on the Woschni experimental formulas, multi-layer wall heat conductivity and also the slight radiation effect in SI engines. With complete heat transfer to the cooling medium and unsteady gas flow in the engine intake and exhaust systems, the simulation model was developed. For the determination of several basic engine thermodynamic parameters for the Suzuki DR-Z400S 400 cc SI engine, a computer program was developed which took into account the 0D model of engine processes in the cylinder and the 1D model of gas flow. The paper presents the measurement results of the effect of the thickness of the ceramic coating on the pressure indicated, the real fuel consumption, the cooling and the loss of exhaust heat. Next, comparisons of effective strength, heat losses in cooling and exhaust systems, total efficiency in engine rotation speed feature and also temperature comparison inside the cylinder for normal, semi-adiabatic and full adiabatic engines are provided. On the basis of the results achieved, the overall performance of adiabatic engines was found to be higher at 2500 rpm, from 27 percent for standard engines to 37 percent for complete adiabatic engines. In order to calibrate the parameters of the combustion process, future work concerning the adiabatic SI engine should be carried out in experimental tests, in particular to establish the Wiebe coefficients and the probability of knock combustion due to higher temperatures at the end of the compression process.

Author (s) Details

Wladyslaw Mitianiec
Cracow University of Technology, Al. Jana Pawla II 37, 31-864 Krakow, Poland.

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