Many organizations have studied the production of a synthetic refrigerant that will produce the least amount of pollution and, at the same time, provide efficient cooling in household use. Freezers, refrigerators and air conditioners are designed to use one type of refrigeration, and can use each other's refrigerants interchangeably. A refrigerant can essentially be made for almost any house appliance that cools something.
R11, or Trichlorofluoromethane, was the first refrigerant to hit the market. Now banned, it was also a big pollutant, contributing immensely to global warming. As of 2010, you will not find any house appliance using R11 refrigerant because of its inefficient nature.
R22, which is Chlorodifluoromethane or Difluoromonochloromethane, is a refrigerant in the process of being phased out. Some old refrigerators and freezers might use it, but it is not commonly used anymore. R22 is a hydrochlorofluorocarbon in composition and, thus, is not as volatile to the environment as its predecessor, R11.
R134A has many names, including 1,1,1,2-Tetrafluoroethane, Genetron134A, Suva134A, and HFC-134A. This refrigerant is a pure hydrofluorocarbon gas, meaning that it contains no chlorine. Its ozone depletion potential is zero. R134A is discouraged because of its high potential contribution to global warming.
R410A is also known as Puron, AZ-20 or GenetronR410A. The mixture that produces this refrigerant is nearly azeotropic, meaning that it cannot be unmixed through distillation. This means that when boiled, R410A remains the same chemical it was in the state before heat was applied. Invented in 1991, it has become quite a common replacement for R22.
R417A is a refrigerant that has been approved for modern equipment as of 2010. It was designed to replace R22, but has also gained a lot of success in commercial application, such as being used as a refrigerant in large freezers in stores. Following the Montreal Protocol, which states that all HCFCs should be banned in developed countries by the year 2020, the move has been made to implement this refrigerant in as many appliances as possible.
R290, better known as propane, is a naturally occurring refrigerant, providing an advantageous and economic solution for cooling. It does, however, present a risk of explosion or fire because of its highly flammable nature. However tempting it may be to use R290 because of its environmentally friendly nature, it must be handled with care.
An alternative and efficient refrigerant, ammonia stands out as a great industrial solution for cooling. Although it sounds like an industry's golden cooling chemical, it is highly poisonous and should not be used in poorly designed systems.