Thermodynamic Modeling of Compression, Combustion and Expansion Processes of Gasoline, Ethanol and Natural Gas with Experimental Validation on a Flexible Fuel Engine

This paper describes the development of a computational thermodynamic model of compression, combustion and expansion processes of gasohol, ethanol and Natural Gas (NG) for the cylinder pressure curve prediction of a Flexible Fuel engine, working with a NG kit installed. The combustion process is modeled using a Wiebe function. Equations for specific heat at constant pressure (C_p) were developed for each fuel for temperatures up to 4000 K.

The model output generates the cylinder gas pressure and temperature, work output and heat release profiles as functions of crank angle, allowing studies of engine performance parameters in different working conditions for each fuel. The differences between the experimental and simulation results were lower than 4% for the maximum cylinder pressure value.