A Diesel Engine Model for Dynamic Drive Cycle Simulations

The development and implementation of a diesel engine combustion system simulation model is described. The model is a crank angle based combustion model, which uses the conditions in the intake and exhaust manifolds together with the fuel injection signal from the engine control unit to estimate the in-cylinder pressure throughout a complete combustion cycle. The model is implemented in Matlab. Furthermore, a Simulink coupling has been developed and implemented such that the combustion model can be connected directly to a Simulink mean value model of an engine air system. The coupling makes the combustion model act like a continuous source and a continuous sink in a mean value model. The coupling makes it possible to continuously simulate an engine in steady-state or transient operation, while the combustion model produces estimated cylinder pressure traces for each combustion cycle. This makes it possible to estimate fuel consumption and to couple the model with emission models which use the cylinder pressure or the rate of heat release as input. The model is developed, calibrated and verified using measured data from a 2.4 liter Volvo diesel engine, equipped with a turbocharger, an exhaust gas recirculation system, and a common rail injection system. The combustion model estimates IMEPnet with a correlation factor of 0.995 for the used data. The simulation time is in the range between 1 and 25 milliseconds for one combustion cycle on a standard computer, depending on the implementation.