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O ORACLE, DIVINE ME THE ANSWER TO THIS QUESTION - howst the fuck does a refrigerator work
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this post was submitted on 16 Oct 2025
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Okay so this is really neat.
The compressor squeezes the refrigerant (a substance which has a low boiling point, usually it's a gas at atmosphere) until it is a liquid, but because of the pressure, is above its boiling point (the temperature at which it would become a gas under normal atmospheric pressure).
Then the liquid is allowed through an expansion valve and into the evaporator, which is a chamber with lots of space inside it. Once the high pressure liquid refrigerant has the space to become a gas - which it must, because its temperature is higher than its boiling point, remember - its temperature falls to its boiling point. This is because when a substance experiences a phase change (liquid to gas in this case), that substance is at the temperature where the phase change occurs, even if it was a different temperature just before.
Now the cold gas makes the metal body of the evaporator cold, air is passed over the evaporator, and heat from the air is transferred to it, and by extension, the refrigerant.
Now the refrigerant passes through to the compressor, which squeezes it into the condenser, where it becomes liquid again.
This explains how to make one, but not really how it works. It’s actually even simpler than that for how.
You remember from physics class how hot things expand (get bigger), and cold thing contract (get smaller)? It works the other way too… make something smaller, by compressing (squeezing) it, and it’ll get hotter. Make something bigger by expanding (stretching) it, and it’ll get cooler. And the key thing is, it does this increase and decrease by basically a set amount.
Another thing you may realize is that temperatures tend to equalize. But a hot thing in the cool air, and the hot thing will get cooler and the air will get warmer. If you put an air-temperature thing in air, neither will change, because both are at the same temperature already.
These two facts are all you need to know to understand a refrigerator.
Step one: take a liquid or gas or something, and equalize it with the temperature in the box.
Step two: take that liquid or gas out of the box, then squeeze it hard so that it heats up. Now, let the hotter liquid or gas equalize with the air OUTSIDE the box, getting cooler.
Step three: stop squeezing the liquid or gas so that it cools back down… but we already lost some heat to the air when it was hotter! So when it cools down, it’ll cool down to LOWER than before.
Now, when we repeat the steps, step one is to equalize with the temperature inside the box. This will lower the temperature in the box!
And that’s how it works. Two physics principles and a little bit of engineering.
The key to "how it works" is the phase change from liquid to gas.
Under normal atmospheric pressure, the refrigerant would be liquid at a very low temperature. Compressing it will make it a liquid at a much higher temperature. Then, releasing that liquid from the pressure allows it to become a gas again - but it's not a gas at the higher temperature. As before, when a substance phase changes from liquid to gas, its temperature becomes the temperature at which it would phase change.
Example: The temperature on Venus is about 867 degrees Fahrenheit. You could use water as a refrigerant there. If you compressed steam on Venus to a pressure where it became liquid water, and then released that water from the pressure, it would become steam again, and it would be 212 degrees F when that happened.
This is the same reason that a can of air duster gets cold when you spray it. The compressed liquid in the can becomes a gas, and its temperature becomes the low temperature of its liquid to gas phase change when that happens.
e: It's not just that "when a specific temperature is reached, the substance changes from liquid to gas", it's also "when the substance changes from liquid to gas, the specific temperature is reached". The two things always happen together.
You're missing the whole latent heat thing that comes with phase change. Most of what you're describing is akin to the air pack you find on an airliner. They do the air conditioning with just squeezing gasses and heat exchangers. They are practical on airliners ONLY because they have a ready supply of compressed air, and when you're burning megawatts of fuel, a few hundred kilowatts of compressor losses are "in the noise". The magic of heat pumps is in the phase change. The critical thing that nets you the near magic heat pumping ability with heat pumps, is the boiling and condensing of the gas and liquid. Also note, you can't practically compress liquids, so your explanation falls apart when suggesting you compress a liquid.