CO_2跨临界膨胀机的开发与实验研究

Development and Experimental Research on CO_2 Transcritical Expander

作为自然工质 ,CO2 制冷系统越来越受到关注 ,然而目前CO2 跨临界循环研究面临的最大问题是如何提高系统效率 ,使之能与普通工质循环竞争。为降低CO2 跨临界循环的节流损失 ,开发膨胀机代替节流阀是研究的重要方向。文中给出开发CO2 滚动活塞膨胀机的依据 ,以及在设计过程中需解决的吸气控制系统、泄漏和摩擦等问题采取的措施 ,同时建立CO2 跨临界循环系统带膨胀机系统的实验装置 ,并对CO2 滚动活塞膨胀机进行实验研究 ,发现膨胀机的输出功与负载有关 ,同时得出膨胀机的最高效率可达到 32 %以上 ,进一步的改进工作仍在进行。

As a natural working fluid, CO 2 is receiving more and more attention in the refrigeration. The key technology of the research of CO 2 transcritcia cycle is to improve the coefficient of performance of the system that is competitive with present conventional high performance refrigerant systems. In order to lower the throttling losses in the CO 2 transcritical cycle, the significant measure is to replace the throttling valve by an expander. This paper presents the development of the rolling piston expander and the activity items in the expander design, including the seal technology, the contact friction control and suction design. The experiments of the CO 2 expander conducted in our CO 2 transcritical cycle rig are described. The results show that the power output of the expander is related to the loads of the generator. The measured efficiency of this prototype is up to 32% and the further improvement of the expander is required.