Effect Of Injection Strategy On The Combustion Of Electronically Controlled Dimethyl-ether Engine

In this work the investigation of the effect of the injection timing and pilot injection on the combustion of the electronically controlled dimethyl ether engine was carried out.The performance and emission characteristics of the electronically controlled dimethyl ether engine with the original engine was compared. It showed that the dimethyl ether engine performed better at low engine speed with lower NOx emissions, the same CO and HC emissions and no smoke.The effect of injection timing on the performance and emissions characteristics under different load was investigated. It showed that as the injection advance angle decreased, fuel consumption decreased firstly then increased and the NOx emissions reduced, while the CO emissions increased, HC remained unchanged and no smoke was detected.The effect of pilot injection timing on the performance and emissions characteristics with EGR was investigated. It showed that with the pilot timing advanced, the combustion heat release model changed from the traditional CIDI to HCCI-DI, the NOx emissions decreased rapidly while the HC and CO emissions increased. EGR effectively reduced the peak pressure and NOx emissions.The effect of pilot injection quantity on the performance and emissions characteristics of the engine with EGR was investigated. It showed that with the pilot injection quantity increased, the combustion heat release mode changed from CIDI to HCCI-DI, the maximum pressure rate decreased firstly then increased, the fuel consumption increased, and the NOx emissions changed a little, while the HC and CO emissions increased rapidly. EGR reduced the HC and CO emissions.The effect of rail pressure on the performance and emissions characteristics of the engine with pilot injection and EGR was investigated. It showed that with the rail pressure increased, the fuel consumption changed unobviously, the NOx emissions increased while the HC and CO emissions reduced. EGR reduced combustion heat release rate slightly and reduced NOx, HC and CO emissions.