Numerical prediction of the performance and emission of downsized two-cylinder diesel engine for range extender considering high boosting, heavy exhaust gas recirculation, and advanced injection timing

摘要

This study investigates the feasibility of a diesel engine to be applied as a power generator to extend the driving range of electric vehicles by evaluating the combustion and emission characteristics of the engine in the process of converting an existing diesel engine to a downsized diesel engine. The study was conducted under a wide range of operating conditions from 1250 to 2500 RPM. In addition, a simulation was performed to analyze the thermal characteristics of the engine under the application of exhaust gas recirculation (EGR) and the responsiveness of the combustion performance to an increase in the boost pressure. The EGR application caused ignition delay and reduced nitrogen oxide (NOx) emissions due to the low combustion temperature. In addition, the increase in boost pressure proved the feasibility of a downsized diesel engine to be used as power generator by improving the lowered performance with the application of EGR. By applying an appropriate advanced injection timing at the maximum load under each operating condition, both the combustion performance and brakespecific fuel consumption were improved; moreover, the NOx emission met the EURO-VI emission regulation. Through verification of the performance and emission of a downsized diesel engine, it was proved that the downsized diesel engine is an effective electric vehicle for power generators.