Extension of a Zero-Dimensional Mixing-Controlled Combustion Model for the Development of a NOx–Free System Based on the Oxy-Combustion Concept

Oxy-combustion is a promising concept to achieve an extremely clean combustion, independently of the fuel type, because, on the one hand, it is a NOx-free combustion and, on the other hand, the CO2 produced during combustion can be easily captured once the water vapor is removed from the exhaust gases stream, consequently allowing also carbon neutral operation. An existing 0D, mixing-controlled combustion model, developed for a standard diesel combustion scenario, has been adapted to the oxy-fuel combustion scenario. Initially, the model over-predicted the heat release at the end of the combustion process. The main model adaptation was to modify the relationship between the average YO2 and the effective YO2 (i.e. the one of the charge actually entrained by the spray), to be consistent with the significant increase in compression ratio needed in the oxy-fuel context. As a result, a model able to correctly predict the combustion behaviour at any operating condition has been obtained, which finally represents a very suitable tool to assist in the concept development.