Progress in ejector-expansion vapor compression refrigeration and heat pump systems

The use of an expansion energy recovery ejector has been given great concern owing to virtues of no moving elements, cost-effectiveness, high reliability and comparable efficiency. This paper is to explore the advancements in ejector-expansion refrigeration and heat pump systems. Firstly, the historical background and operating principles of ejector are described. In the second part, the theoretical and experimental progresses of the standard ejector-expansion systems as well as some special issues are presented. The third part of the paper focuses on the other novel ejector-expansion systems, including liquid recirculation ejector-expansion systems, dual evaporator ejector-expansion systems, cascade ejector-expansion systems and parallel multi-ejector expansion systems. Finally, conclusions and prospects are drawn, suggesting the inherent mechanisms and the future striving of the ejector-expansion refrigeration and heat pump systems.