All you need to know about CO₂ as a refrigerant.
HERMETIC – in CO₂ business for over 50 years.

Carbon dioxide (CO₂) is an old refrigerant, first patented in the United Kingdom in 1850 by Alexander Twinning, where it was subsequently used in air-conditioning and marine applications. With the development of the CFC, HCFC, and HFC synthetic refrigerants beginning around 1930, CO₂ decreased in popularity, all but disappearing by 1960. 

Over the next two decades or so, it was experimentally determined that CFC and HCFC refrigerants were depleting the earth’s upper atmospheric ozone layer at a rate that would likely cause its disappearance. In response to these findings, many countries agreed to halt the production of these CFC and HCFC refrigerants within an appropriate time frame, allowing the ozone layer to replenish. This agreement is called the Montreal Protocol where its second and fourth amendments concern CFCs and HCFCs. 

At this same time, Lorentzen proposed CO₂ as an alternative refrigerant for the CFC and HCFC refrigerants. After CO₂’s reintroduction, applications first appeared with mobile air conditioning and heat pump water heaters. Other applications soon followed, which include CO₂ as a heat transfer fluid, low-temperature refrigerant in a cascade refrigeration system, or as the sole refrigerant. 

In North America, more than 150 supermarket transcritical and other CO₂ systems are in operation, and over 70 NH₃-CO₂ industrial subcritical cascade systems operating with many being planned.