Refrigerants are used in the process of refrigeration. Refrigeration is a process whereby heat is removed from a substance or a space. A refrigerant is a substance that picks up latent heat when the substance evaporates from a liquid to a gas. This is done at a low temperature and pressure. A refrigerant expels latent heat when it condenses from a gas to a liquid at a high pressure and temperature. The refrigerant cools by absorbing heat in one place and discharging it in another area.
Desirable properties of a good refrigerant for commercial use are
■ Low boiling point
■ Safe nontoxic
■ Easy to liquefy and moderate pressure and temperature
■ High latent heat value
■ Operation on a positive pressure
■ Not affected by moisture
■ Mixes well with oil
■ Noncorrosive to metal
There are other qualities that all refrigerants have. These qualities are molecular weight, density, compression ration, heat value, and temperature of compression. These qualities will vary with the refrigerants. The compressor displacement and compressor type or design will also influence the choice of refrigerant.