Theoretical Model for Prediction of the Spark Engine Operational Cycle Using Natural Gas

This paper presents a model for simulation of the thermodynamic cycle of a spark ignition engine operating with natural gas. The combustion process is expressed in function of the fuel mass fraction burned. The convective heat transfer is correlated to the heat transfer coefficient. Curves of pressure and temperature inside the combustion chamber in function of the crank angle are then obtained. Prediction of performance and energetic balance of the system are also defined. The simulation results are compared to published experimental data, in order to validate the model.