In 1805 o. Evans originally proposed the idea of using volatile fluids in closed cycles to freeze water into ice. He described a system that vaporizes ether in a vacuum and pumps the steam to a water-cooled heat exchanger, where it condenses and is used again. In 1834 Perkins first developed and patented the steam compression refrigeration cycle. Diethyl ether (ethyl ether) was used as a refrigerant in the steam compression refrigeration equipment he designed.
Early refrigerants, almost all of them were flammable or toxic or both, and some were highly corrosive and unstable, or some were under too much pressure, often causing accidents.
Mechanical refrigeration appeared in the middle of the 19th century. Jacob Perkins built the first practical machine in 1834. It uses ether as a refrigerant and is a vapor compression system. Carbon dioxide (CO2) and ammonia (NH3) were first used as refrigerants in 1866 and 1873 respectively. Other chemicals include the chemical cyanide (petroleum ether and naphtha), sulfur dioxide (R-764) and methyl ether, which have been used as refrigerants for steam compression. Its application is limited to industrial processes. Most food is still preserved in ice collected in winter or prepared by industry.
