For more than 150 years natural refrigerants have been used in various industrial applications reaching temperatures from -273°C to more than 300°C and the level of the high temperature limit is difficult to estimate at the time of writing this paper. Ammonia, NH3, R-717 has been the preferred refrigerant for normal everyday industrial refrigeration in strong competition with hydrochlorofluorocarbon (HCFC) R-22.i In other applications carbon dioxide, CO2, R-744 used to be one of the preferred working fluids in the early days of refrigeration. In the 1980’s it became apparent that chlorine, Cl, was destroying the ozone layer that protects all life on earth from the dangerous ultraviolet (UV) rays emitted by the sun. The discussion leading up to the Montreal Protocol elaborated on what would be the right way to choose if chlorinated and fluorinated hydrocarbons were not the way to go. Many alternative fluids were suggested, and Gustav Lorentzen suggested to reconsider carbon dioxide, which he saw in operation in his young days when sailing as marine engineer. Others suggested hydrocarbons, which are a large family of various types of natural occurring gasses with many different properties. Hydrocarbons have been used in the chemical process plants in various applications and temperature levels for more than 130 years.