中文摘要：

二氧化碳作为具有环保潜质的自然工质，在最近10年越来越受到人们的关注。然而不足的是，二氧化碳的跨临界循环还存在效率低的问题。为了降低由于超临界节流造成的不可逆损失，采用膨胀机代替节流阀，并回收膨胀功，以提高系统的循环效率。开发了二氧化碳跨临界循环水源热泵摆动膨胀机，并进行结构对比和强度分析。对二氧化碳跨临界循环水源热泵系统进行试验测试，分析表明摆动转子膨胀机结构适合在高压下工作，在试验测试条件下，膨胀机的效率可以达到44％。

英文摘要：

Due to the advantage of global environmental protection, carbon dioxide, the natural refrigerant, has been attracting increasing attention over the last ten years. The low performance efficiency of the CO2 transeritical cycle is the main problem for the practical application. In order to reduce the irreversible loss caused by the throttling process f~om the supereritical region to the sub-critical and improve the coefficient of performance of CO2 cycle, an expander is adopted to replace the throttle valve and recover the expansion power. A hermetic swing expander in transcritical carbon dioxide cycle water source heat pump is developed. The structure of swing expander and stress on the swing piston are analyzed. The experiment on CO2 transcritical cycle water source heat pump is conducted. The results indicate that swing expander is suitable for the operation under high pressure. Under the test condition, the efficiency of the swing expander can reach 44%.