Evaluation of Losses in the Cycle for a Diesel Engine and Improvement of Its Thermal Efficiency (exergy Analysis of the Theoretical Cycle)

This paper is to evaluate available energy loss, i.e. exergy loss caused by irreversible process in the theoretical cycle for two stroke and four stroke diesel engines. All exhaust energy from the cycle has been summarized into three losses, (1) exergy loss at the heat receiving process which is inevitable in the thermal power system, (2) exergy loss in the scavenging process peculiar to the diesel engine cycle, (3) heat loss dissipated with the exhaust gas and the cooling water. Each exergy loss is distinctly expressed with the area in the T-s diagram. Improvement of the thermal efficiency depends on the reduction of the exergy loss in each process. Super-charging is effective not only to increasing power, but also to reducing exergy loss. Exergy losses are different between two stroke and four stroke diesel engine cycles.