How a Refrigerator Works

Recall that heat naturally flows from a hot object to a cold object. However, in a refrigerator heat is taken from the inside of the cool refrigerator and expelled to the warm air in the kitchen. In order for this to happen, work must be added.

The diagram below shows in more detail how a refrigerator removes heat. It includes the use of cooling and condensing coils, freon, and a compressor. The points below the diagram explain each step of the process.

• Heat from warm food is transferred to the cool liquid freon (or similar substance) in the cooling coils of the refrigerator.
• As the liquid gains heat, it changes to vapour.
• The vapour is compressed into hot vapour in the compressor. Work is done here by the compressor.
• The hot vapour is pumped to condensing coils outside the refrigerator (usually on the back).
• Heat is transferred from the hot vapour to the cooler condensing coils, which then transfers the heat to the surrounding air.
• As heat leaves the freon in the condensing coils, the vapour turns back to liquid.
• The high pressure liquid passes through an expansion valve, becoming less pressurized as it returns to the cooling coils back in the refrigerator.

How your fridge works (animated)

[Back to thermodynamics page]