Engine cycle modeling

Compression-ignition engine models, also known as Diesel or CI (Compression Ignition) engines, differ from SI (Spark Ignition) engine models in that they take into account a far greater number of physical and chemical processes. In fact, heat release in homogeneous spark-ignition engines is essentially controlled by the propagation speed of the flame front, and therefore by the internal aerodynamics of the combustion chamber. , whereas in compression-ignition engines we need to take into account fuel injection and atomization, droplet vaporization, the chemical mechanisms of combustion initiation and finally combustion. The present dossier focuses solely on the modeling of the physical and chemical phenomena involved in diesel combustion, bearing in mind that general models for the following engines have been covered in previous dossiers and :

• zero-dimensional thermodynamic approach ;

• thermodynamic gas model ;

• wall loss model ;

• kinematic model ;

• transfer model.

Compression-ignition engine models in the literature cover a very wide spectrum, from empirical models incorporating very little physics, to detailed multi-zone models incorporating all the general models mentioned above, via models of intermediate complexity, generally with a single zone. The choice of model type in a given context will be dictated by the trade-off between accuracy and computation speed.

For symbols and notations, the reader is referred to .