Heat Balance Analysis Using Cylinder Pressure Obtained by Engine Experiments Considering the Spatial Heterogeneity of Diesel Combustion

The method described in this paper has been proposed to analyze the heat balance of diesel combustion from engine measurement data considering the heterogeneity of this type of combustion with use of a two-zone model composed of unburned and burned zones. This method is intended for practical application to an engine bench test during an engine development process and is characterized by the following features: A representative excess air ratio of the burned zone is set and assumed to be constant throughout the combustion period, and the ratio is estimated from NOx emission amount. The authors performed heat balance analyses on engine measurement data using the proposed method and made a comparison with the results of analyses that assumed a combustion chamber to be one homogenous zone. The comparison indicated that the heat balance analyses by the proposed method with the two-zone model were able to capture the influence of the heterogeneity of diesel combustion on cooling loss and exhaust loss more properly.