Keywords: diesel engine cycle, exergy analysis, irreversibility, thermal efficiency, performance improvement, two-stroke diesel engines, four-stroke diesel engines, exergy losses, energy losses, turbocharging
Exergy analysis of a diesel engine cycle and its performance improvement
This paper aims to evaluate available energy losses, i.e. exergy losses caused by irreversible processes in the theoretical cycle of two-stroke and four-stroke diesel engines. All exergy losses in these cycles have been divided into three categories: exergy loss in the heat receiving process which is inevitable in thermal power systems; exergy loss in the scavenging process peculiar to the turbocharged diesel engine cycle; heat loss dissipated with the exhaust gas and the cooling water. The quantity of each exergy loss was distinctly expressed with the corresponding area in the T-s diagram. The thermal efficiency of the cycle is improved by reducing the exergy losses in each process. Turbocharging is effective not only in increasing power, but also in reducing the exergy loss. The distribution of exergy losses of two-stroke and four-stroke cycles are different to each other.