How does a refrigerator work?

In the sides of a refrigerator are pipes that contain a cold fluid. This makes the inside of the refrigerator cold. The cold fluid is pumped through the pipes to carry heat away from the food in the refrigerator and keep it cold. 

The fluid that circulates in the pipes of the refrigerator easily changes from a liquid to a vapor. As it enters the interior, it is liquid and is pumped through an evaporator. This lowers its pressure and it becomes vapor. The change from liquid to vapor makes the vapor cold because it takes up heat.