The CO2 transcritical refrigeration system has become one of the most popular research topics in the refrigeration field owing to its numerous advantages such as environmental friendliness

excellent heating performance

low-ambient-temperature adaptability

and full range of working conditions. In this paper

the development status of transcritical CO2 refrigeration or heat pump technology in vehicle air conditioning

building heating and hot water supply

drying industry

commercial cooling chain

and other industries is discussed. Based on the development status

this paper also summarizes and presents a prediction on the future development trend of the transcritical CO2 technology. The CO2 refrigeration technology has a bright future in the field of vehicle thermal management. Its heating performance is higher than those of R134A

R407C

R1234yf

and other systems. However

its cooling performance should be further improved. For the application of building heating and hot water supply

the development of the transcritical CO2 technology has been relatively completed. Different structural optimization schemes have been proposed for different temperature requirements. The next step of the research will mainly focus on the industrialization of the existing mature technology. Additionally

although the transformation of distributed small-scale drying equipment into a new energy version has yet to be achieved

the transcritical CO2 technology

which has significant advantages in energy saving and environmental protection

has excellent promotion prospects in the field of heat-pump dryers. In addition

because of the mature state in the commercial cold chain field

its excellent energy conservation and environmental protection advantages will further advance the technology into the refrigeration field of ice-making and snow production in stadiums. In this new field

the integrated application of cooling and heating effects of the transcritical CO2 technology will be the main research direction in the next stage. In-depth research on pressure energy recovery technologies such as ejectors

vortex tubes

and expanders is an important means to improve the system energy efficiency. An intelligent control technology is necessary for real-time performance optimization of transcritical CO2 systems. These two aspects will become the main tasks of the transcritical CO2 technology research in the next stage.