The adoption of highly efficient vapour-compression heating, ventilation, air conditioning and refrigeration (HVAC&R) systems is compulsory to achieve a low-carbon society. Expansion work recovery using a two-phase ejector is widely recognized as one of the most promising measures to improve the energy efficiency of HVAC&R units. This holds true for all operation conditions provided that an effective capacity control technique is implemented. In this work a thorough critical review on the current status of the presently available capacity control strategies for two-phase ejectors was carried out. In addition, their pros and cons as well as the comparison of their performance were reported. It was concluded that two-phase ejectors can be properly capacity controlled in large- and medium-scale vapour-compression units. However, a suitable capacity control mechanism for small-scale vapour-compression solutions still requires a major breakthrough and is being intensively discussed among experts in the field.

必须采用高效的蒸气压缩加热，通风，空调和制冷（HVAC＆R）系统，以实现低碳社会。使用两相喷射器进行的膨胀功恢复被公认为是提高HVAC＆R单元能效的最有希望的措施之一。只要实施有效的容量控制技术，所有操作条件均是如此。在这项工作中，对两相喷射器的当前可用容量控制策略的现状进行了全面的批判性审查。此外，还报告了它们的优缺点以及性能对比。结论是，在大中型蒸汽压缩装置中，两相喷射器可以得到适当的容量控制。然而，