Validation of On-board Polytropic Index Prediction Model for Compression Stroke of CI Engines Using Measurements of In-cylinder Local Heat Flux

Abstract

The authors previously developed the on-board polytropic index prediction model for compression stroke, which is a part of models for Model Based Control. The present study compared between the cooling losses and polytropic indexes predicted from our developed model and those measured under four different driving conditions. It was confirmed that the averaged relative errors of cooling loss prediction, under the base condition and various load conditions, were evaluated to be 4.9% and 7.3%, respectively. Additionally, the averaged relative errors of polytropic index prediction under the base and various load conditions were evaluated to be 0.1% and 0.7%, respectively.