Effects of variable specific heat ratio of working fluid on the performance of an irreversible Diesel cycle

Abstract

SYNOPSIS The effects of the variable specific heat ratio of the working fluid on the performance of a Diesel cycle, with considerations of heat transfer and friction-like term losses, are investigated by using finite time thermodynamics in this paper. The relationships between power output and compression ratio, between thermal efficiency and compression ratio, as well as the optimal relationship between power output and efficiency of the cycle, are derived by detailed numerical examples. The results obtained herein show that the effects of variable specific heat ratio of working fluid on the power output and thermal efficiency of the cycle are significant and should be considered in the design of practical Diesel engines.