Performance Evaluation of an Air-Standard Miller Cycle with Consideration of Heat Losses

There are heat losses during the cycle of an actual engine, which are neglected, in the air-standard analysis. In this paper, performance of an air-standard Miller cycle with consideration of heat losses is evaluated, assuming that the heat loss through the cylinder wall only occurs during combustion and that to be proportional to the average temperature of both the working fluid and cylinder wall. In addition, effects of various design parameters, such as the compression ratio, the supplementary compression ratio, the initial temperature of the working fluid and the constants related to combustion and heat transfer through the cylinder wall on the net work output, the thermal efficiency, the maximum work output and the corresponding compression ratio and thermal efficiency at maximum work output are investigated. Miller cycle now is widely used in the automotive industry and the results obtained in this paper will provide some theoretical guidance for the design optimization of the Miller cycle.

Keywords:

Air-standard cycle , Miller cycle , Combustion , Working fluid , Combustion , Heat transfer , Compression ratio , Net work output , Thermal efficiency , Maximum work output