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The Science of Refrigeration

Wondering about refrigeration? Let us teach you. Read on to learn how your fridge works.

Here's how your refrigerator actually works

Refrigeration is essential to our lives in one very important way: it keeps food cold. This may seem like something so simple and common sense, but without refrigerators perishable food items would never reach our neighborhood grocery stores. This is not only essential for moving goods from city to city, but on a bigger scale, importing fruits, vegetables, and meats from one country to another would be impossible.

Refrigerators (and freezers) make our lives more comfortable (and healthy) by keeping food chilled while preventing it from spoiling. HVAC, which stands for Heating, Ventilation, and Air Conditioning would also not be a part of our realities, as these systems use the same kind of technology as refrigerators.

If you're shopping for a new refrigerator, you might wonder: how exactly does it keep your food so cold?

Here comes the science. There are a number of laws that deal with refrigerators and what they do. One of the most essential is the Second Law of Thermodynamics, which states that heat will naturally move from a high temperature(hot or warm) area to a low temperature (cold) area. If you’ve ever opened the front door in the dead of winter, you might notice that heat escapes the house and moves to the colder, outside area. That’s the Second Law at work.

In order to reverse this natural high to low flow of heat, we need to apply force. In this way, heat is forced against its natural cycle and moves from a cold area to a hot one. Refrigerators and air conditioners use something called condensers to force this action.

Moving from State to State: The Moving Parts

Moving from state to state, for example, is when a liquid becomes a gas state and vice versa. Refrigerators and air conditioning units accomplish this by using something called refrigerant, which is usually a liquid substance or mixture that is pumped through the unit. The cycle works like this: the refrigerant goes through a compressor, becomes hot gas, turns into liquid, and is then converted into a cool gas. The cool gas cycles back to the compressor and the process repeats.

The refrigerant flows in a closed path around the system. Much like when water, propane, and other fluids exist in vapor, gas, or liquid states, (depending on temperature and applied pressure), refrigerants do this very same thing. The refrigerant fluids are much more suited to the purposes of refrigerators, so the “boiling point” is at a significantly lower temperature than water.

Pipes majorly help in this process, which in refrigerators and air conditioners, are half inside, half outside the units. Inside, the wide structure of the pipes allow the built-up gases to move with ease. When the gas expands, it cools, causing it to absorb heat from the unit.

At this point, the refrigerant (now in liquid form) moves to the pipe on the unit’s exterior, where it becomes more narrow. Because the space is small it has no choice but to compress, heat up, and return to its gas state. This heated gas is transported to the outside of the unit in this cycle. If you’ve ever felt the back or sides of refrigerator, this is the exact reason they are warm when we touch them.

Energy Conservation

Another law that comes into play when it comes to refrigeration is Conservation of Energy. The old adage, “energy cannot be created or destroyed” lies at the heart of this law. If energy becomes trapped in a closed space, it does not go away, however, it can transfer energy states.

There are a number of other scientific principles and rules that deal with refrigerants and their appropriate functions, however the ones discussed above are the most essential and noteworthy. As long as nature operates under these principles, heat can be transferred from cold to hot areas, and maintained at a cool temperature for as long as necessary. In this way, refrigerators are allowed to do what they do best: keep food cold.

Our modern way of life would be seriously compromised without the technology behind refrigerators and air conditioning units. Make sure your refrigerator is performing optimally and that your food is staying cool, cold, or frozen, depending on your needs. And the next time you sneak down into the kitchen in the middle of the night for some strawberry cheesecake, remember all the good that your fridge does for you.

Resources— Bright Hub EngineeringScienceDirect, WisdompageExplainthatstuff,

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