Just a few minutes after you put warm food in a refrigerator, the food feels cooler. The refrigerator carries the heat from the food into the room outside.
How does a refrigerator do this? When a liquid changes to a gas it evaporates. As it evaporates, it takes heat from the things around it. Also, when a gas changes to a liquid, it condenses, and gives off heat.
Refrigerators are cooled by a special liquid that is easily turned into a gas and then back to a liquid. First, the cool liquid is pumped to tubes inside the refrigerator, where it evaporates. As the liquid changes to a gas, it takes heat from the air inside the refrigerator. This makes the refrigerator cooler.
Then the warm gas is pumped into tubes outside the refrigerator, where it condenses. As the gas changes back to a liquid, it gives off heat. When the liquid cools, it is pumped back into the refrigerator. There it evaporates again. In and out it goes, carrying heat from the refrigerator and keeping the food cold.
Do you ever feel chilled when you get out of the bath or after swimming? This is because the water on your skin is evaporating off your body. It goes into the air where you can’t see it. As this happens, it takes heat away from your body, making you feel chilled.
Water vapour in the air sometimes clings to objects. On a hot day water vapour sticks to a cold glass of water. As more vapour sticks to the glass, it condenses, forming droplets of water on the outside of the glass.
Picture Credit : Google