跨临界CO₂喷射器系统优化调节技术综述

With ihe adoption of the EU F-Gas Regulation 517/2014, carbon dioxide (R744, CO₂) as a refrigerant has become a current research hotspot. In order to deal with the problem of loss of expansion work in transcritical carbon dioxide refrigeration and heat pump systems, it is one of the common methods to use an ejector instead of a throttling valve as the main expansion element. For the problem of ejector adjustment in the transcritical CO₂ ejector system, the operating characteristics of the ejector system were introduced, and the research status of the ejector adjustment problem in the system was reviewed, and some mainstream adjustment methods and techniques were summarized, including changing the nozzle geometric structure, adopting adjustable throat area injectors, adopting multi-ejector solution, etc., and the advantages and disadvantages of different methods were compared and analyzed. The adjustable throat area method is an effective method to adjust the optimal high-pressure side pressure under a given working condition, but the presence of the pointer reduces the ejector efficiency. The multi-ejector combination method has the adaptability of working conditions, the high efficiency of the ejector and the ease of control concurrently.