In old refrigerators, ammonia gas is used to keep the refrigerator cool. Pure ammonia gas is highly toxic to people and if a refrigerator containing it leaked, it would pose a threat. Switching to CFCs was a nontoxic replacement that depleted the ozone layer. Then they switched to a more environmental friendly coolant. Although many refrigerators still use ammonia. (Brian; Elliot, 2006).
Refrigerators need five major components to keep cool. The compressor compresses the ammonia gas and the compressed gas heats up as its pressurized. The coils on the back of the refrigerator let the hot ammonia gas disperse its heat and the gas condenses into liquid at high pressure. The high pressure ammonia liquid flows through the expansion valve. One side of the valve has high pressure ammonia liquid and the opposite side is a low pressure area because the compressor sucks gas out of that side.
The liquid ammonia immediately boils and vaporizes with the temperature dropping to -27 degrees Fahrenheit which makes the inside of the fridge cold. The compressor sucks up the ammonia gas and the cycle repeats. (Brian; Elliot, 2006)The coolant is trapped inside coils and makes a circuit through them and changes back and forth from a liquid to a gas.
Ammonia gas does not affect the Ozone layer but it is highly toxic to humans. When they switched to CFCs, thats when the refrigerators added to the list of things depleting the Ozone Layer. Du Pont discovered this replacement in the 1930s. They are used in a variety of industrial, commercial, and household applications. The CFCs were released into the atmosphere and went up into the stratosphere. In the 1970s, it was discovered that the CFCs in use are harmful to the Ozone Layer. The ultraviolet radiation at the atmospheric altitude breaks down CFCs, freeing the chlorine. Under the proper conditions, this chlorine has the potential to destroy large amounts of ozone. As of the 1990s, they put a more environmental friendly coolant in refrigerators.