Emissions–calibrated equilibrium heat release model for direct injection compression ignition engines

The heat release analysis of an internal combustion engine is essential for understanding the process of combustion, with models commonly used as tools during engine testing. This effort describes a zero-dimensional (0-D), three-zone model (burned, unburned, and fuel mass zones) for computing the rate of heat release using in-cylinder pressure–time history. Each zone is thermodynamically independent except for the shared use of the pressure trace. By utilizing fundamental mass and energy balances, the model balances numerical accuracy with time-efficient computation. Improvements to the literature in this area include the incorporation of an Arrhenius-based function for the rate of combustion, freeing the user from having to diagnose the duration of the combustion event. Additionally, this methodology allows the rate of heat release to be calculated from a thermodynamic analysis of the change in the bulk gas as indicated by the pressure trace. The model is calibrated to a combustion efficiency found through a separate emissions analysis, providing a stable numerical platform. Model results demonstrate the rate of heat release of various fuel chemistries (mineral diesels, oxygenates, and other fuels) and testing modes (Exhaust Gas Recirculation), utilizing pressure data acquired from the testing of a single-cylinder compression ignition engine.