How Refrigerators Work

Ever wonder how the inside of your refrigerator stays so cold? Why does the rear always feel so warm? What’s that clicking motor sound that kicks on every so often? Is that months-old container in the back holding meat or is it cake? Well, we might not have all the answers, but for the rest we have you covered!

Diagram of the Refrigeration Cycle A diagram of the refrigeration cycle.

It’s likely that most refrigerators that you’ve seen are compression-style refrigerators. These refrigerators use a simple principle to create a cooling effect: Using vapor or liquid to carry away heat. This principle was first practiced by Oliver Evans in the early 1800s and has stayed as the refrigeration standard to this day.

Here are the basic parts of a refrigerator, as it goes through the thermodynamic cycle:

It all starts with the refrigerant. The refrigerant is a substance (often tetrafluoroethane) that has an incredibly low boiling point; somewhere around -26 °C (or -15 °F). First, the refrigerant gas is compressed by the compressor. (This is the motor sound that you occasionally hear behind your fridge.) Under pressure, the gas begins to heat up, wanting to boil and expand.

It’s then run through the large heat-exchanging coils along the back of the refrigerator so that the heat can evenly dissipate. As it cools throughout the coils, the refrigerant starts to condense into its liquid form.

The cooled refrigerant then flows through the expansion valve of the evaporator, where it begins to evaporate into gas. This gas travels through coils inside of the refrigerator, surrounding the food compartments. As it travels and further expands, it captures the heat from inside of the fridge and carries it back out to the rear of the fridge. The gas re-enters the compressor and the cycle begins again!