The first refrigerator with motor-driven 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 at 1925. In the first refrigerator, the electric compressor and the refrigerator were separated, and the latter was usually placed in the cellar or storage room of the family and connected with the electric compressor through pipes, and then they were combined into one. Before 1930s, most refrigerants used in refrigerators were unsafe, such as diethyl ether, ammonia water and sulfuric acid. Flammable, corrosive or irritating. Later, I started looking for a safer refrigerant and found Freon. Freon is a non-toxic, non-corrosive, non-flammable fluorine compound, which quickly became the refrigerant of various refrigeration equipment and has been used for more than 50 years. However, it has been 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.