中文摘要：

二氧化碳跨临界循环需要利用膨胀机回收功以提高循环效率．在单缸滚动活塞膨胀机的基础上，提出了双缸滚动活塞膨胀机，分析了进气控制结构，进气管中余隙容积的存在会损失一部分膨胀功；分析了两缸内工作腔的吸气、膨胀、排气过程；在一定工况下，设计了双缸并联滚动活塞膨胀机；根据设计的结构参数进行了运动分析和受力计算上下两缸的活塞与滑板之间的摩擦力以及活塞上的气体力是平衡的，只需要平衡惯性力矩即可。

英文摘要：

The efficiency of the trans-critical CO2 cycle can be increased by recovering the work with expander. A two-cylinder rolling piston expander was proposed on the basis of single-cylinder rolling piston expander, and the inlet mechanism analysis shows that the clearance volume exists and will reduce some expansion work. Also the entire process of inlet, expansion and outlet was analyzed. A two-cylinder parallel rolling piston expander was designed in the operating condition, and the movement analysis and calculation of the forces were done according to the designed structural parameters. The results show that friction forces between sliding vane and piston are balanced, and so are the gas forces between working fluid and piston. Therefore, only the moment of inertia is needed to be balanced.