Study of advanced engine operating strategies on a turbocharged diesel engine by using coupled numerical approaches

Abstract

As a consequence of the negative influence of the transport sector on the environment, the European Union imposed a series of regulations that aim at reducing its harmful effect. Therefore, in the last decade, the increase in engine combustion and thermal efficiency, and a decrease in exhaust gas emissions are the primary goals of diesel engine research. The efficiency increase of the entire engine cycle is achieved by introducing different advanced operating strategies, such as optimisation of injection process and employment of various exhaust gas recirculation and engine boosting systems. This research presents a numerical study on the efficiency improvement of a turbocharged diesel engine using advanced engine operating strategies. A single operating point of a production type diesel engine was modelled by using the computational fluid dynamics tool AVL FIRE™. The results of released heat were transferred to a cycle engine simulation created in AVL BOOST™ that covers the entire engine system, including the intake and exhaust flow path, low and high pressure exhaust gas residual loops, exhaust gas residual and intake charge cooling, and turbomachinery. The cycle simulation was used to assess the entire engine system performance and cycle efficiency for different engine operating strategies. With the analysis performed in this work, it was concluded that the highest engine brake thermal efficiency of 31.86% could be achieved if a high pressure exhaust gas recirculation loop without electric compounding turbocharger is used.