The
study of the thermodynamic properties of engine fuels and the
in-cylinder gas is involved in the analysis of chemical compound reaction
and the thermodynamic analysis of fuel and gas, which is quite important
in engine combustion investigations because the fuel chemical energy
converts into internal work energy during this stage. Although the
research on the thermodynamic properties of fuel and in-cylinder gas
has lasted a few decades, with the development of new fuel types,
developing general models with sufficient accuracy to calculate the
fuel and in-cylinder gas thermodynamic properties for engines remains
a challenge. This paper presents a model to calculate the diesel fuel
and in-cylinder gas thermodynamic properties based on the mixture
composition theory and considering the diesel fuel and in-cylinder
gas mixtures in terms of the chemical reaction fundamentals. The diesel
fuel and in-cylinder gas thermodynamic property modeling approach
for the combustion investigation is then applied in the heat-release
calculation model of a marine diesel engine, which is validated by
experimental research on heat release. According to the simulation
and experimental results, when considering that the diesel fuel and
in-cylinder gas thermodynamic properties are affected by the in-cylinder
temperature, fuel type, and air excess ratio, the engine combustion
simulation results in predictions that are more accurate than those
when setting the values constant. This paper provides a general approach
for the investigation and application of engine fuels and in-cylinder
gas thermodynamic properties, in particular for new fuel substitution
in engines.