How does a refrigerator work? You'll be surprised!
There are a lot of misconceptions out there about refrigerators and how they work. Here we'll clear the air and explain in simple terms how they actually function. In addition, we'll give you an idea of why they're used in the first place and how they've changed over time. Let's start with the basics. A refrigerator is a cooling apparatus used to reduce the temperature of some material below that of its surroundings (i.e., reduce its temperature to less than that of the environment).
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3 Key Elements in Refrigerator Technology
Coolant/Refrigerant: Refrigerators contain a number of coolants, but they all work by absorbing heat from within and releasing it to the outside. The most common coolants are CFCs (chlorofluorocarbons), which contribute to ozone depletion in our upper atmosphere. In 1998, many countries agreed to phase out these materials. Other coolants include CO2, which is generally mixed with other gases like butane and propane; hydrocarbons; ammonia; or combinations of these gases mixed with water. Of course, at present there's no perfect replacement for CFCs as an inexpensive, long-lasting refrigerant. But alternatives do exist and may be used in some refrigerators today—sometimes even those made here in North America or Europe.
A Brief History of the Refrigerator
It’s hard to believe now, but at one time there was no such thing as refrigeration. Before electric refrigerators came into fashion in the 1920s, people had to find other ways of storing food and drink. The first fridges were called ice boxes and they actually used ice to cool things down. But these primitive fridges worked on natural laws of physics that we’re all very familiar with now—and it turns out they used exactly the same scientific principles as our modern-day electrical fridges do. So how did these early ice boxes manage to keep things cool before electricity became popular?
A Mechanical Model
Most refrigerators in commercial and residential use are variations on one of two fundamental designs. The first, referred to as an absorption model, is basically just a giant thermos with ammonia gas used to create cooling. That ammonia expands when it gets warm, taking up more space inside. When it cools off again, it contracts and takes up less space inside. By cycling between hot and cold temperatures over and over, your refrigerator can keep food cool without requiring much energy input from you.
An Electrical Model
Most refrigerators use an electrical circuit to reduce temperature within it. An electric motor drives a compressor, which compresses gas and increases its pressure; in most models, that gas is refrigerant R-22 (also known as Freon), although newer models may use one of several alternative gases. Increased pressure of any gas causes it to cool down; however, R-22 changes from a liquid to a gas at -30 °C (-22 °F), which allows it to further cool its surroundings. A condenser transfers heat from inside the refrigerator into its own cooling coils, then outside air or another cooling source (such as an air conditioner) dissipates that heat outside.