The refrigerator does this by providing a consistent low-temperature environment, and it does this using the power of evaporation. A common misconception about how refrigerators work is that they blow cold air into their compartments to bring the temperature down. What they actually do is take the heat out of the air inside and transfer it outside. When a liquid evaporates in to the air, it absorbs heat. This is why your skin feels cold after rubbing your hands with alcohol.
This is also why we sweat when our body temperature gets too hot. Instead, it gets reverted back to its liquid form to start the cycle all over again. The refrigeration cycle is deceivingly simple — it only requires four main parts to achieve it. The cycle goes like this:. It all starts with the compressor. This part is known as the heart of the refrigerator.
The compressor increases the pressure and the temperature of the refrigerant gas, and pumps it into the condenser. The condenser is the set of coils located at the back of the fridge. Its job is to condense the hot high-pressure refrigerant gas from the compressor into its liquid form.
This liquid is then pumped into the expansion valve. Also known as the capillary tube, this part greatly reduces the pressure of the liquid refrigerant, thus bringing its boiling point down.
The low pressure liquid is passed along the evaporator coils where — you guessed it — it will gradually evaporate. After this, the low pressure liquid is cycled back to the compressor where the cycle will start all over again. You may have noticed that some refrigerator start and stop during the day. This is because an internal thermostat regulates the refrigeration cycle. When the fridge gets too cold, it switches the compressor off, and when it gets too warm, it turns it on again.
Non-inverter refrigerators are like this, as their compressors cannot operate in variable speeds. When the sensor senses that it's cold enough inside a refrigerator, it turns off the compressor. If it senses too much heat, it switches the compressor on and begins the cooling process again. Refrigerators work by causing the refrigerant circulating inside them to change from a liquid into a gas. This process, called evaporation, cools the surrounding area and produces the desired effect.
You can test this process for yourself by taking some alcohol and putting a drop or two on your skin. As it evaporates, you should feel a chilling sensation - the same basic principle gives us safe food storage. To start the evaporation process and change the refrigerant from liquid to gas, the pressure on the refrigerant needs to be reduced through an outlet called the capillary tube.
The effect is similar to what happens when you use an aerosol product such as hair spray. When you release the contents into the lower pressure open space, it turns from a liquid to a gas. To keep a refrigerator running, you need to be able to get the gaseous refrigerant back to its liquid state, so the gas needs to be compressed to a higher pressure and temperature again.
This is where the compressor comes in. As mentioned earlier, the compressor provides a similar effect to that of a bike pump. Refrigerators use the principles of pressure , condensing and evaporation of a fluid in a closed circuit to remove heat and reduce the temperature inside the fridge. The fluid is called the refrigerant and the picture shows how it is moved around the circuit to cool the space in the fridge.
You can see in the diagram opposite the different components that make a fridge work and how they fit into the cabinet. Compressor: Gas at low pressure and low temperature enters the compressor. The gas is compressed to a higher pressure and its temperature rises just like a bicycle pump which gets warmer pumping up a tyre. This uses electricity.
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