中文摘要：

膨胀机工作过程模拟是以膨胀机实际工作过程为研究对象，综合各种因素，建立数学模型，利用计算机对模型进行数值求解，分析了膨胀机中工质的主要热力参数以及其能量、质量及功率等变化特性，计算了膨胀机输出功和效率等主要参数，通过分析，揭示了膨胀机的内部工作规律和改进膨胀机性能的途径。

英文摘要：

The expansion process in CO2 rolling piston expander was studied. Considering many influenced factors, the mathematic models were set up. By numerical calculation, the main thermal parameters during the expansion process and some characteristics about energy, mass and output of expander were analyzed. The efficiency and power output of expander were calculated. Based on the calculated results, the principle of the expansion process could be known and the expander could be improved.