Former President of International Refrigeration Society G. Lorentzen proposed the use of CO2 as an environmentally friendly refrigerant and transcritical cycle theory. The advantages of CO2 in environmental protection and performance have attracted more and more attention from scholars around the world.The development of its systems and components has also been greatly developed. Current research results show that the CO2 system has lower refrigeration performance than conventional systems at high ambient temperatures (above 45°C), similar to traditional systems at 35 to 45°C and has better performance below 35°C. At present, the application of CO2 transcritical cycle in automotive air-conditioning, heat pumps, commercial refrigeration equipment, food refrigeration and other applications are very good. Its performance is equivalent to (even better than) the original R22 or R12 or R134a refrigeration device. It is particularly suitable for applications where large temperature changes are required. Moreover, its performance is better at lower evaporation temperatures.
As a natural refrigerant, CO2 has advantages that are unmatched by other non-natural working fluids in terms of its physical characteristics. With the continuous deepening of research work on CO2 refrigeration system, CO2 will be further promoted as a new generation of refrigerant. It is believed that in the near future, automotive air-conditioning systems, commercial refrigeration systems, residential air-conditioning systems, and heat pump drying systems for various manufacturing companies will use CO2 in large quantities to replace existing refrigerants.
As a refrigerant, people want it to be environmentally friendly, efficient and economical, but in fact there is no perfect refrigerant. Compared with other refrigerants, CO2 has obvious advantages such as environmental protection, safety, economy, and unit volume refrigeration capacity, but it also has deficiencies in terms of work pressure and efficiency. Current research shows that as long as a reasonable selection of the thickness of the pipe and pipe wall can ensure the safety and reliability of the CO2 system operating under transcritical pressure. The rational improvement of the CO2 transcritical cycle method can effectively reduce the throttling loss and improve the system's cycle efficiency. CO2 as one of the environmental refrigerants has a good application prospect. With the development of refrigeration and air-conditioning technology, it will be widely used.
CO2 unit cooler