Comparison of EF7.TC Engine Performance in Two Modes of CNG Fuel and Petrol using Piston and Combustion Chamber Thermal Simulation

In this study، the heat transfer of SI engine piston is calculated. Engine performance in two modes of CNG fuel and petrol has been studied. For thermal simulation، three different models have been used. In the first model، three approximate and constant temperatures are selected for piston، cylinder and cylinder head، and subsequently the temperature، pressure and convection coefficients of the in-cylinder gas are determined using two-zone combustion model. In the second model، for each of the walls (piston، cylinder and cylinder head)، the relevant heat transfer equations with two-zone model are solved considering three unknown temperature. In the third model، which is the most accurate method، 24 heat transfer equations coupled with the two-zone model are solved simultaneously based on resistor-capacitor thermal network model. Eventually، results of the three models are compared to study their effect on the piston thermal behavior. It has been shown that use of resistor-capacitor model with lower number of equations and consequently less solution time is an appropriate method for solving problems of engine heat transfer. The simulations were carried out by a MATLAB code and the results were validated with the experimental data of the EF7. TC engine.