What does electricity do to remove heat from air?
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You know how when you’re spraying a can of dusting air, how the can gets a lot colder, and eventually frosts over?
That’s because when gas that’s compressed is un-compressed, it gets colder. This is because of physics.
In the exact same way, when gas that is “loose” gets compressed, it heats up.
So…
Imagine you have a big container of gas, and the container allows you to compress and un-compress the gas. Like… a tank with a piston.
It is currently un-compressed, and room temp.
Go outside and compress the gas in the container. It gets hot, so you then have a fan blowing outside that cools it off so that it’s not hot anymore.
Bring the room temp compressed gas back inside, and then un-compress it. It gets really cold, so you can then use a fan to blow the inside air past the cold gas container, and it makes the inside air cold. This also warms up the gas that you just un-compressed.
Bring the room temp un-compressed gas back outside, and compress it again. And so on and so forth.
Pack it all into a little machine that is half inside and half outside, and the machine just keeps doing that to the gas in a constant loop.
Air conditioning takes the heat from one place and moves it to another place. In this case, it takes the heat from the room and puts it outside. It does this by using the heat in the room to boil a liquid into a gas, which puts the heat from the room into the gas. Then it squeezes that gas back into a liquid, putting that heat into the compressor. Then it exhausts that heat out the back into the outside.
There’s a compressor in the a/c unit. Air from the room is compressed, which takes all the heat in a volume of air and concentrates it. Then that hot air is cycled through a coil on the outside portion of the unit, and outside air is blown over it with a fan, which takes a lot of that heat away (this is why the a/c unit blows hot air on the outside). Then, that compressed air is fed through a little orifice, where it’s allowed to expand very quickly, which causes it to get very cold. That goes through another coil on the inside part of the unit, and inside air is blown over it, which heats up the coil and cools off the air. This causes cooled air to blow into the room, and it causes that air in the coil to get warm. Then it’s compressed and fed outside again… rinse and repeat.
1. Compress a gas, making it extremely hot (Like 120-140 Degrees Fahrenheit)
2. Move the hot gas outside
3. Blow lots of outside air over the gas to cool it to ambient temperature (Removing energy from the system)
4. Let the gas expand rapidly, causing it to cool (Down to around 30 Degrees Fahrenheit) and become a liquid
5. Blow lots of room air over the liquid, cooling the air and warming the liquid until it evaporates (Adding energy back into the system while removing it from the room)
This all works because refrigerant has an extremely low boiling point (40-50 degrees Fahrenheit) and because compressing things adds energy which is released as heat, while allowing them to expand does the opposite.
Ever seen liquid nitrogen before?
When something gets cold, it gets smaller. Gas turns to liquid, Liquid to solid.
When you compress something to make it smaller, the same thing happens. It gets colder.
An air conditioner uses a motor and electricity to compress a substance called a refrigerant.
Air is then blow over the refrigerant making the air cold, and then it’s pushed into a room by a fan.
Try blowing air across an ice cube and you’ll get a similar effect.
ELI5.
Cold is very hard to make. Heat is very easy to make.
An AC is actually heating a liquid outside. This heated liquid is “chilled” by “cooler” outside air. This “chilled” liquid can then be brought inside.
Note: Answer omits heating process and liquid pressure.
Refrigeration cycle. Start with a room temp, low pressure gas. Compress it with a compressor, now you have high pressure gas, but it’s hot from compressing. Then gas goes through an outside unit (condenser) where it runs through a coiled tube and a fan blows outside air across it to cool it. Now you have a high pressure, outside temperature fluid that has condensed to a liquid. Then it goes through a throttle valve, and the pressure drops as it tries to squeeze through the valve to the other side. The pressure drop makes the temperature drop too, so now you have a low pressure, low temperature mix of gas and liquid. This is what you needed, a cold fluid. Then the fluid goes through an inside unit (evaporator) where it runs through a coiled tube and air from the room is blown across it. The air in the room is cooled down by giving heat to the cold fluid, and the cold fluid is warmed back up. Then the fluid gets sucked back into the compressor to start again.
The electricity is used to turn motors that run the compressor, the outside fan, and the inside fan.
It runs a pump that moves hot gas out and lets cold gas/fluid in.
More specifically, is uses the property that increase in pressure of a substance also increases its temperature, and that the temperature between two materials will always try to equalize.
The pump moves a *refrigerant* (a fluid that increases in temperature with pressure more than others) inside your AC to the outside unit, where it increases in pressure and heats up warmer than the temperature outside. It cools off until it’s the same temperature as outside, then comes back to the indoor unit where the pressure and consequently temperature are reduced dramatically. The refrigerant then absorbs the heat from inside and repeats the cycle.
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