Compression Ratio Optimization in a Direct-Injection Diesel Engine: A Mathematical Model

This paper describes the development and results of a mathematical model for a single cylinder, naturally-aspirated, direct-injection diesel engine, used to study the effect of compression ratio on the different performance parameters. The parameters investigated include; thermal and mechanical efficiency, ignition delay, mean effective pressure, maximum cylinder pressure, mechanical friction, and blowby. The model simulates a full thermodynamic cycle and considers the intake and exhaust processes, instantaneous heat transfer, instantaneous friction, and instantaneous blowby. Based on the model results, a prediction of an optimum CR for the engine is made.