Research progress and applications of transcritical carbon dioxide heat pumps: A review
DOI:
https://doi.org/10.18686/cest.v1i2.118Keywords:
transcritical; CO2 refrigerant; heat pump; application status; reviewAbstract
Heat pump technology is an energy-saving technology that can efficiently utilize low-grade energy. It has broad application prospects in building heating, industrial waste heat utilization, new energy, and other fields. However, the refrigerants used in traditional heat pump systems have serious negative impacts on the environment, and there is an urgent need to find a safe, environmentally friendly, and efficient alternative refrigerant. As a natural refrigerant, CO2 has good physical and chemical properties and is very suitable as a working fluid in transcritical cycles, showing great advantages in the field of heat pump technology. At present, research on CO2 heat pumps has made certain progress, but there are few reviews of the research status and development trends of CO2 heat pumps in different applications. Therefore, in this article, the latest research results of transcritical CO2 heat pumps in different application fields are systematically summarized, pointing out the difficulties such as high pressure and low operating efficiency in system design and operation. The latest optimization research works on system components, cycle structure, mixed refrigerants, and control strategies are also summarized. The results showed that each optimization method can significantly improve system performance, among which mixed refrigerant is the simplest optimization method. Finally, the outlook for CO2 heat pump technology is put forward. With policy support and technological advancement, a more comprehensive, energy-saving, and intelligent CO2 heat pump technology will continue to be developed and innovated.
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