CO2 belongs to the so-called “Natural” refrigerants, together with e.g. ammonia, hydrocarbons such as propane and butane, and water. While ammonia is a great all-round refrigerant for industrial refrigeration applications, its use is sometimes limited in areas where toxicity or flammability is a concern.
In these and in a number of other applications, CO2’s unique properties make it an attractive alternative:
CO2 is both non-toxic and non-flammable. In places where it is allowed to use only a limited amount of ammonia, cascade or secondary CO2 systems are a great solution.
CO2 cascade systems are very efficient for low temperature applications. E.g. for freezing fish. With CO2 it is possible to freeze the fish faster and to lower temperatures, thus improving the quality and consuming less energy than in the same freezing process using other refrigerants.
CO2 is excellent as a brine. The circulation rate required for efficient freezing with CO2 is very low, thus reducing the size of the pumps, as well as the energy consumption. Heat transfer efficiency of CO2 is nearly constant for all practical temperatures, which makes it very attractive as a brine for low and medium (up to 0 ºC) temperature applications
Technical developments since the 1920s have removed many of the barriers to the use of CO2, which once existed. However, CO2 users must still be highly aware of its unique properties and take the necessary precautions to avoid problems in their refrigeration systems. Danfoss specialists can help you to select suitable components, and the literature found on this website covers a great deal of Danfoss experience with CO2 applications.