A comprehensive review of compression high-temperature heat pump steam system: status and trend

Compression high-temperature heat pump steam system (HTHPSS) has higher energy efficiency than electric, coal-fired and gas boilers for steam production. The system efficiently recovers waste heat from the factory and the CO2 emissions can be reduced depending on the driving electricity mix, which is in line with the carbon neutral energy saving and environmental protection development strategy. However, there are few reviews published in the existing literature that specifically address the status of research on HTHPSS. This work not only reviews the status of research on compression HTHPSS in two directions: increasing the efficiency of high-temperature heat pump (HTHP) and increasing the steam temperature, respectively, but also indicates the future development trend of HTHPSS. The key to the research of HTHP is the development of high-temperature refrigerant and high compression ratio compressors. In this work, the refrigerants that can be used in HTHP are reviewed. Natural refrigerants R718 show promise as HTHP refrigerants because they have zero ozone depletion potential (ODP), zero global warming potential (GWP) and a high critical temperature. In addition, the research status of high-temperature and high-pressure compressor with a focus on their design and strategies for reducing the discharge temperature of scroll, piston, and screw compressors. The future focus of research is to develop a high compression ratio for the compressor. Moreover, the three main water vapor compressors, centrifugal, Roots and screw compressors, are introduced respectively. Finally, according to the operational requirements of the compression HTHPSS, research trend and the technical problems to be solved are proposed.