When giving injections, doctors and nurses disinfect our skin by wiping it with alcohol. When they do this, you may feel a slight burning sensation on your skin. This is because when the alcohol evaporates, it removes heat from the skin.
Refrigerators use this property to cool down. However, conventional refrigerators have used chlorofluorocarbon gas instead of alcohol. This is the CFC gas that has become a major environmental problem because it depletes the earth's ozone layer.
Freon is a very convenient substance that can quickly change from a liquid to a gas and from a gas to a liquid.
This CFC is circulating in the pipes inside and outside the refrigerator. When the inside of the refrigerator needs to be heated, liquid CFC is evaporated to heat the refrigerator, and when the evaporated gaseous CFC reaches the outside of the refrigerator, it is converted to liquid. In this way, the heat from inside the refrigerator is dissipated into the air around the pipes. In this way, the CFC carries the heat inside the refrigerator out of the refrigerator. This is how the air inside the refrigerator is heated.
The refrigerator can be thought of as automatically repeating this process in the pipes.