How a Refrigerator Works

Before a liquid changes into a gas, it must be heated. We see this happening when a kettle boils on a fire. Before a gas can change into a liquid, it must lose heat. This is the principle on which a refrigerator works.

All refrigerators must, therefore, contain a liquid refrigerant which can turn easily into a gas and back again into a liquid. A refrigerator stores food, and so it is much better if the liquid is clean and safe and has no strong smell. For this reason, most refrigerants are chemicals which contain the gas fluorine. They have all the necessary qualities.

At the bottom of a refrigerator there is an electric pump. This pump forces the liquid through a pipe to the top of the refrigerator. Here the pipe branches out into many channels around the freezer box. The liquid spreads itself out through these channels and becomes a gas. But in order to change into a gas, it must be heated; and so it takes heat from the freezer. So the freezer becomes the coldest part of the refrigerator, where water turns to ice and food is frozen.

Any warm air in the refrigerator rises towards the freezer and helps to change the liquid refrigerant into a gas. The gas flows round to the bottom again, where the pump compresses it. When this gas is compressed, it loses heat; and turns back into a liquid. The heat escapes from the refrigerator into the air outside. The liquid refrigerant now starts its journey again and soon reaches the freezer. There, it draws in more heat and again becomes a gas. And so the process goes on and on.

Short Answer Questions

1. Why is a refrigerator cold inside?
2. How can a gas be given a liquid form in a refrigerator?
3. What is the most necessary quality of a food refrigerant?
4. How does the refrigerant become a gas in a refrigerator?
5. What is the use of the electric pump in a refrigerator?

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