Technical Paper
Optimum Compression Ratio Variation of a 4-Stroke, Direct Injection Diesel Engine for Maximum Brake Power and Torque and Minimum Soot and NOx Emissions
1999-08-02
1999-01-2728
The thermodynamic simulation model for the performance of a 4-stroke, direct-injection (DI), variable compression ratio (rc), diesel engine, previously developed by the authors [1], is used to investigate the effect of varying compression ratio (rc) on engine brake power and torque and engine soot and NOx emissions. An optimization analysis is conducted to an engine with specifications similar to HELWAAN M114 under normal operating conditions to seek optimum rc variation to achieve some specific targets. For constant maximum brake power or constant minimum soot emission, the analysis shows an enormous increase in maximum cylinder pressure inside the variable rc engine reaching about 19.8 MPa compared to 10.7 MPa for constant rc engine, which means difficult practical applicability. For constant maximum brake torque, the optimized variation of rc lies within the range of 16.4 to 19.3.
