Comparison Between MCC and MZCM Combustion Models

This paper evaluates the ability of two combustion models to predict a small HSDI diesel engine operation after changing its operational parameters. Both Multi-Zone Combustion Model (MZCM) and Mixing Controlled Combustion (MCC) are inherently coupled to the fuel injection process allowing great freedom of simulation for multistage injection engines but also requiring consistent calibration of the model parameters. In the present work, two operating conditions of a reference research engine are modelled and tuned in the AVL Boost® software using both MCC and MZCM to model the combustion process. The operational conditions evaluated are defined by changes in EGR rate, fuel injection start and distribution, boost pressure, and injection pressure. The predictive ability of each model is assessed by comparing the output results accuracy and the number of parameters changes needed to tune the model for a given change of operation. The novelty of this work resides in the comparison of the two models, as built in the software, in a practical simulation process. Both models have a similar amount of base parameters to be tuned, but MCC performed slightly better in predicting engine performance, while MZCM has the disadvantage of not accurately predicting the burned zone temperature after shifting operational conditions.