Refrigerant is a medium used for refrigeration, which plays a role in the transfer of heat in the refrigeration circulation system. The refrigerant absorbs the heat in the slaughter, and then is compressed, cooled, expanded and evaporated in the refrigeration cycle system, so as to discharge the heat outdoors and reduce the indoor temperature. The main functions of the refrigerant are as follows: Courier heat: the refrigerant transfers heat in the refrigeration circulation system, thereby reducing the indoor temperature and improving the refrigeration efficiency: the refrigerant has a high refrigeration efficiency and can work at a lower temperature, thereby improving the refrigeration efficiency. Environmental protection: Some refrigerants have a high greenhouse effect and damage to the ozone layer, so it is necessary to use environmentally friendly refrigerants to protect the environment.