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The objective of this work was to develop simplified soot models for use with a direct injection diesel engine combustion simulation. The soot models, when used with the combustion simulation, were required to be able to predict engine exhaust emissions trends, to be sensitive to major combustion system variables, and yet to be efficient enough to be used with an engine cycle simulation and formal mathematical optimization procedures. The background of soot formation in diesel engines is reviewed and the assumptions for the models are discussed. The resulting models have global soot formation and consumption steps with an Arrhenius temperature dependence. The choice of the model constants, the selection procedure for the constants, and the sensitivity of the constants to engine operating conditions are presented. General considerations for the testing of emissions models and possible extensions of the soot models are discussed.

This work reviews the differences in fuel economy between two direct injection diesel engine versions through the use of a First Law energy balance and a Second Law availability balance. Both experimental data and simulated results are used in the analysis. The use of an engine simulation allowed the important processes in each engine to be analyzed and a Second Law effectiveness calculated. The availability balances and effectiveness values were used to determine the effect of major engine components on the fuel economy. A comparison was also made with an ideal engine with selected perfect or reversible processes. The Second Law analysis was carried out using the thermodynamic property availability and a chemical and thermo-mechanical dead state appropriate for diesel engines. The results of the analysis show the sources of the irreversibilities and availability losses during the engine cycle and what engine components are responsible.