Keywords: spark ignition engines, entropy generation minimisation, thermodynamic analysis, exergy, variable valve timing, VVT, variable compression ratio, VCR, simulation, laws of thermodynamics, heat transfer, combustion, working fluids, intake, exhaust
Thermodynamic analysis of Spark Ignition engines using the Entropy Generation Minimisation method
The recent improvement on Spark Ignition Engines has been the result of improved engine thermodynamic cycles, made possible by advances in technologies such as Variable Valve Timing (VVT) and Variable Compression Ratio (VCR). To evaluate the potential of these techniques a thermodynamic analysis is made. Numerical models were implemented in Matlab Simulink using the laws of thermodynamics and include heat transfer, combustion, real working fluid characteristics and intake and exhaust events. The second law analysis allowed the identification of inefficiency sources and directions for improvement. A SI engine was analysed and its processes were evaluated by the amount of entropy generated.