Evaluation method of the exhaust system of the turbocharged diesel engine based on exergy and enthalpy analyses

In this paper, thermodynamic analysis of the engine exhaust process is carried out on a turbocharged inter-cooled diesel engine. The exergy analysis method is proposed to evaluate the energy quality transfer efficiency of the exhaust from the inner side of exhaust valve of diesel engine to turbine inlet. On the other hand, enthalpy analysis method is adopted to evaluate the conversion process of thermal energy to power in the turbine. Several evaluation analysis cases of a turbocharged engine are carried out by means of simulation. The results show that the design of engine exhaust system has influences on exhaust gas flow process in exhaust system and in turbine in different ways. In order to obtain most power from the exhaust gas of engine by the turbine under certain condition, the impacts of both exergy loss in exhaust system and power conversion efficiency have to be considered at the same time. That means a trade-off point has to be found.