ABSTRACT
Refrigeration are well known as the fluids absorbing heat during evaporation and are classified into two groups, primary and secondary refrigerants. Primary refrigerants, which provide a cooling effect during the phase change from liquid to vapor, are commonly used in refrigeration, air conditioning, and heat pump systems, as well as plants. Secondary refrigerants play a role in carrying heat from an object or a space being cooled to the primary refrigerant or the evaporator of a refrigeration system. The halocarbons, which contain one or more of the three halogens chlorine, fluorine, or bromine, have been widely used in refrigeration and air conditioning systems as refrigerants and are more commonly known by their trade names, such as Freon, Arcton, Genetron, Isotron, and Uron. Carbon dioxide is one of the oldest inorganic refrigerants. It is a colorless, odorless, nontoxic, nonflammable, and nonexplosive refrigerant and can be used in cascade refrigeration systems and in dry-ice production, as well as in food freezing applications.
