Have you ever been asked the question: “What is refrigeration?” Most people answer “Refrigeration is making something cold.” Actually, making something cold is the end result of refrigeration. The true definition of refrigeration is: “The removal of heat from one place and transferring it somewhere else.” If you stop and think about it, and then compare it to your actual experiences, you can understand how this takes place. The cold area actually becomes cold because you remove the heat from it. Once you remove the heat, you must deposit it somewhere else. (Generally outside)
From our high school chemistry class, we know water comes in three different forms:
1. A solid called “ice.” 2. A liquid commonly called “water.” 3. A “vapor or gas,” which we see as a cloud. Water is ice at temperatures below 32 degrees F; is a liquid at temperatures between 32 degrees F and 212 degrees F; and a gas at temperatures above 212 degrees F.
Refrigerants work in a similar manner. However, the temperatures between when refrigerant is a liquid and a gas are much closer together than the 32 degrees F and 212 degrees.
Please look at the illustration of a walk-in cooler. Look at the bottom of the diagram shown below and you will find that the liquid refrigerant is stored in a “receiver” tank located between the condenser and the expansion valve. When a thermostat (a device in the area to be refrigerated) senses that it needs to be cooler, it sends a signal to the expansion valve, and it spits some liquid into the “Evaporator. ” The evaporator looks like a large radiator located in the area to be cooled. As a fan pulls the air through the evaporator, the refrigerant begins to absorb the heat from the air, thus making it cold. As the refrigerant absorbs the heat, it begins to boil just like water does, and at the exit end of the evaporator becomes a vapor/gas. Just as you would boil water and it becomes a vapor/gas, so does the refrigerant.
Moving along the cycle towards the compressor, the gas is compressed and is under higher pressure and moves toward the condenser. Here the heatis blown off into the air, and just like a cloud that condenses and becomes rain, the refrigerant condenses and also becomes a liquid once again. Once condensed to a liquid, it is again stored in the receiver until the thermostat calls for it to start the cycle once again in the expansion valve.
This is called a simple refrigeration cycle. Your refrigerator at home works on the same principle. To prove it to yourself, feel the warm air blowing on your feet. That is the heat that has been removed from the inside of your refrigerator.
Another example is the air conditioner in your home or car. Go outside and stand in front of the condensing unit outside your home during the summer, and you can feel the heat being blown off. That is because the evaporator in your unit attached to the ducts in your house is removing the heat from them, and then transferring it outside.
To conclude, just remember: Refrigeration is the process of removing heat from one place, thus making it cold, and putting it somewhere else.
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To learn more about refrigeration, check out our tips and traps section here.