The development of a diesel engine model using one-dimensional (1-D) fluid-dynamic engine simulation codes,and its validation using experimental measurements are described in this paper.The model was calibrated by running the engine on an electric dynamometer at eight steady-state operating conditions.The refined engine model was used to predict the oxides of nitrogen (NOx) less than those measured earlier in the experiments,and hence to recommend changes in the engine for the verification of the results.The refined engine model is greatly influenced by the start of injection angle (ψ),ignition delay (φ),premix duration (DP),and main duration (DM) for the prediction of reduced NOx emissions.It is found that optimum ψ is 6.5° before top dead center (BTDC).At this angle,the predicted and experimental results are in good agreement,showing only a difference of up to 4%,6.2%,and 7.5% for engine performance,maximum combustion pressure (Pmax),and NOx,respectively.
