The first refrigerator that used an electric motor to drive a compressor was invented by Swedish engineers Brighton and Mendes in 1923. Later, an American company bought their patent and produced the first batch of household refrigerators in 1925. The electric compressor and the refrigerated box of the original refrigerator were separated. The latter was usually placed in the kiln or storage room of the home and was connected to the electric compressor through pipes. Later, the two were combined into one. Before the 1930s, most of the refrigerants used in refrigerators were unsafe, such as ether, ammonia, sulfuric acid, etc., which were either flammable, corrosive, or irritating. Later, I started to search for safer refrigerants and found Freon. Freon is a non-toxic, non-corrosive, non-flammable fluorine compound. It soon became the refrigerant for various refrigeration equipment and has been used for more than 50 years. However, it was also found that Freon has a destructive effect on the ozone layer of the earth's atmosphere. So people began to look for new and better refrigerants