Simulation Techniques for Heat Release Calculation of Diesel Engines

Heat release analysis in diesel engines is a powerful method to investigate the combustion process and engine performance. The aim of this study is to simulate the heat release rate during combustion using the measured in-cylinder pressure based on thermodynamic principles. After determining the submodels such as mass and composition, gas and fuel properties, heat of combustion, heat loss to the walls, and others the overall simulation model is set up in MATLAB/SIMULINK. The gas and fuel properties are simulated as functions of temperature and composition resulting in accurate and varying c_v, u, h etc. The heat release rate calculation is very sensitive for the heat loss model. In the paper an empirical Woschni model is applied, and its uncertainties are discussed. The simulation model was verified by a MAN 20/27 diesel engine test bed and the results prove that the simulation model is reliable and useful for engine analysis.