Modeling and simulation of two-stage expansion air-powered engine

The structure of two-stage expansion air-powered engine (TSEAPE) was proposed, and the mathematic sub-models of its working process in each stage were built up respectively based on the thermodynamics analysis. Taking advantage of the relations among the state variables of the air in the two stage cylinders during the air exchange processes, the two sub-models were combined into a whole to describe the full working process of the TSEAPE. Based on the model, the engine performance was simulated, and the analysis results were compared with those of the single-stage expansion air-powered engine (SSEAPE). The results show that the two-stage expansion mode can improve the torque and efficiency of the air-powered engine, and enable the engine relatively stable and highly efficient under different intake duration angles in a wide range.