Simulation Research on Hybrid Pneumatic Engine Aided by Internal Combustion Cylinder Supercharged with Pneumatic Engine Exhaust

To improve performance and fuel economy of the pneumatic-internal combustion hybrid system,a supercharging way to direct the high pressure exhaust of pneumatic engine into the internal combustion engine(ICE)cylinder to fully use pneumatic engine exhaust energy was studied.The pneumatic-internal combustion hybrid system mathematical model was built up based on thermodynamics theory and validated through bench tests.Based on the model,pressure and mass flow rate characteristics of the pneumatic engine exhaust and performance of the hybrid system were analyzed under constant speed and intake pressure conditions.Results show that with the pneumatic engine intake pressure rising,both IC engine indicated mean effective pressure and hybrid system power increase,the max.total energy efficiency improves by 11% compared to original.Under constant pneumatic engine intake pressure,with speed increasing the hybrid system power increases first reaching apeak value,then decreases due to limitation of the pneumatic engine cyclic intake air amount and the hybrid system total energy efficiency lower gradually,it is increased by 5%~15%than unsupercharged.It is concluded that the proposed supercharging-aiding measure can improve the hybrid system power and economy in medium and low speed ranges.