| Opposed piston two-stroke diesel engines (OP2S) have difficulties in turbocharging matching and balancing turbine energy under low speed conditions. It is necessary to seek a turbocharging method with better matching characteristics and lower energy loss to improve the full speed energy utilization efficiency and overall performance of the engine. Based on an OP2S concept prototype, the thermodynamic simulation model of electric assisted turbocharging of OP2S diesel engine with different combined modes was established, and the full operating characteristics of the engine were studied. The results showed that the exhaust energy was insufficient at low speeds of exhaust gas turbocharging, limiting the engine to operate only within the range of 2300-3000rpm. The use of electric assisted turbocharging can broaden its operating range; When the electric driven compressor is pre mounted, it distributes a higher pressure ratio and requires higher intervention power than the rear mounted compressor. The middle mounted motor directly drives the connecting shaft of the exhaust gas turbocharger, minimizing energy loss. Referring to the connotation of effective thermal efficiency, the in-cylinder energy utilization rate is defined to evaluate the efficiency of conversion of heat power, and the exhaust energy utilization rate is defined to evaluate the degree to which the turbocharger utilizes the exhaust energy. Under low speed conditions with electric assistance intervention, achieving the same cycle power output, the intervention power required for middle type is 0.1-0.2kW lower than that for the rear type and 0.5-0.7kW lower than that for the front type; The in-cylinder energy utilization rate of the middle type is 0.2~0.3% higher than that of the rear type and 0.9-1% higher than that of the front type. |
