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Environmental pollution is of great concern; hence the emission norms for the diesel engines are made more stringent. The purpose of this work is to develop a process to optimize the FIS parameters and select a most suitable FIS by simulation to meet the target emissions. During the combustion optimization exercise of diesel engine, different hardware combinations like injector, HPP etc are matched through testing to achieve the required performance and emissions. The process requires the real testing of the engine on engine dynamometer with various hardware combinations, which is expensive and time consuming. A simulation model of diesel FIS is constructed using ‘AVL Hydsim’. The model is validated by comparing the predicted and the experimental results. The validated model is used for further work. Critical parameters were listed based on the sensitivity analysis on the base model.

This paper is focused on the prediction of in-cylinder pressure, temperatures and engine-out NOx. One of the important factors influencing engine output parameters is the rate of heat release, which affects the in-cylinder pressure, temperature and engine out emissions. A single-zone model is formulated for prediction of heat release and in-cylinder pressure. Being a predictive model, this model does not required cylinder pressure as an input. Combustion pressure is predicted by modeling compression pressure, ignition delay, heat release, and heat loss. Required Sub-models have been obtained from the literatures. Fuel burning rate is predicted using Watson model. To retain the computational efficiency and better prediction accuracy a two-zone model has been formulated to predict NOx emissions. Flame temperatures are predicted by enthalpy balance. Thermal NO concentration is predicted by using basic Zeldovich mechanism.