The first generation of refrigerant in about 1830) 1930 years of 100 years, because of the development of society, we choose artificial refrigeration process, the courage of the refrigerant to explore. It can be seen that these refrigerants are some solvent and have volatile media. They are toxic, flammable or both, a single refrigerant there is a strong corrosive and unstable, and perhaps too high pressure is not safe, so often when the use of trouble. During the first 50 years of the period, various cooling skills were in inquiry. The late-stage steam-cooled chillers, air-circulating refrigerators, absorption chillers and water-evaporative refrigerators have just dominated the refrigeration industry for a century.
The steam-tightening cooler began to use ether, methyl ether as refrigerant, ammonia, carbon dioxide, sulfur dioxide (China in 1966 also use SO2 machine 2 double ball freezer) and methyl chloride in the late have been used, especially the use of ammonia, The refrigeration technology has been carried out agile, around 1900, the United States, Britain and Germany, the compressor is simply selected ammonia and CO2.20 century early, centrifugal compressor used the first use of dichloroethane refrigerant. The airtight chillers are initially icened by pre-tightening air (open cycle). Later, the use of R. Stirling closed regeneration cycle, they were widely used in 1900 before the vessel refrigerated and ice.
2nd generation refrigerant 1931) During the development of the second generation refrigerant in 1990, there was an urgent need for both safe and durable refrigerants because of the dramatic increase in the need for artificial refrigeration. In the 2 times after the oil crisis, efficient air conditioning industry into a new refrigerant requirements. At this time there are halogenated hydrocarbons (CFCs, HCFCs) -based refrigerant. Since the beginning of 1931, R12, R11 and R22 with excellent thermal function of the refrigerant with a new look dominated the refrigeration industry for about 60 years, they are safe (A1 group))) non-toxic, non-flammable) and efficient HVACR industry has brought gold development time.
The third generation of refrigerants (1990) 2010) begins with the late 1970s, and it is noted that CFCs (including refrigerants) consume a lot of ozone in the stratosphere, and the ozone is present over the Antarctic. Thus, the Montreal Protocol 6 and 5 of the Vienna Treaty 6 proposed a time limit for the replacement and replacement of CFCs for substances that could be used as transitional substances in a short period of time. As can be seen from Table 3, the second generation of refrigerant is basically attributed to CFCs substances, have a higher ODP value. Thus, the third generation of refrigerant to maintain the ozone layer for the selection of norms. However, the long-term use of halogenated hydrocarbon refrigerants, we still attach importance to the fluoride in the material (ie, HFCs).
4th generation refrigerant (2010)) The third generation of refrigerants has succeeded in reducing the depletion of the ozone layer. However, in sharp contrast, the global warming trend is becoming more severe: / global uniform air and ocean temperatures rise, , The global average sea level rise and other phenomena have been very obvious [1] 0. In accordance with the rules of the United Nations Climate Change Structure Treaty (UNFCCC) 5 Kyoto Protocol 6: Class 6 gases such as carbon dioxide, methane, nitrous oxide, HF2Cs, PFC and SF6 are classified as greenhouse gases and have been proposed for developed countries to reduce greenhouse gas emissions The The third generation of refrigerants, HFCs, have a high global greenhouse effect potential, and some countries are likely to pay taxes on the use of these refrigerants. Which makes the fourth generation of fire burning eyebrows. For the condition of the fourth generation of refrigerant candidate substances, their thermal function and safety are comparable to those of CFCs and HCFCs, and it is clear that there is an unprecedented challenge in choosing the fourth generation of refrigerants.