At present, most of the refrigerants used in the refrigeration and air-conditioning industry are CFC (collective term for chlorofluorocarbons) and HCFC (hydrochlorofluorocarbons) . These substances have a destructive effect on the ozone layer and produce a greenhouse effect. Climate change caused by current environmental warming, The ozone hole has become a global environmental problem. If it is allowed to develop, it will pose a severe challenge to human survival and development. Therefore, in the future, the research on refrigerants can no longer only focus on the thermophysical properties of refrigerants, but pay more attention to its environmental protection, and should pay attention to the coordinated and sustainable development of the ecological environment and human beings. Generally speaking, the development trend of refrigerants should meet the requirements of sustainable development of the ecological environment and promote its further development. According to the core requirements of the coordination of economic development, resource protection and ecological environment protection in sustainable development, there are two development directions for refrigerants in the future:
The first is environmental protection. The use of environmentally friendly refrigerants has become a general trend. Green environmentally friendly refrigerants can be synthetic or natural. Although synthetic environmentally friendly refrigerants will not cause damage to ozone, they can be from the earth's ecology. From the perspective of sustainable development, natural refrigerants are the most ideal choice, because natural refrigerants originally exist in the earth's ecosystem. Whether they are used or discharged into the environment, they are taken from nature and returned to nature, and their impact on the environment is more than synthetic. The refrigerants are much smaller. I believe that with the continuous advancement of technology, natural refrigerants will surely develop greatly.
At present, R22 is the most used refrigerant in various fields. However, due to the depletion effect of R22 on the ozone layer and the higher greenhouse effect value, the research on HCFC22 alternative technology is underway.
Although HFC substitutes have solved the problem of ozone depletion, its high GWP value is still a problem that can not be ignored. If considering the acceptability of the environment, natural refrigerants are undoubtedly the most thorough and complete way to solve the problem. At present, the mixture of ammonia, propane and other hydrocarbons and CO refrigeration technology are used in natural refrigerants. Among them, CO refrigeration technology is most likely to become a long-term substitute for R22. Due to the high density and low viscosity of CO, the flow loss of CO is small and the heat transfer effect is good.