I know that there’s the things in the attic that blow the air but what about the things outside the house with the large fans?
In: Technology
The big loud thing outside moves heat from the air inside it into the air outside it. It blows the now-cooler air inside the house to cool it.
If the big loud thing were inside, it would dump more heat into your house than it cools from air inside it, which wouldn’t help cool your house at all.
They’re part of a singular system. You have a fluid that can relatively easily change from liquid to gas and back again through pressure. At one end, you compress the gas, condensing it, and heating the air, and at the other, you evaporate the gas, which cools the air. You keep those sides separate, and you can actively cool an area.
On the outside, the refrigerant is compressed, which will condense it to a liquid under high pressure, and also cause the fluid to release energy as heat. There will also be a large heatsink/fan so this now hot fluid can cool down a bit (discharging best to the surroundings)
On the inside, that high pressure fluid is allowed to expand, which will cause it to absorb heat from the surroundings. A heatsink/fan here will cool down air as it passes over it. The now low pressure refrigerant is piped back outside and the cycle repeats.
The blower inside a house has a fan blowing over a coil which has a very cold liquid running through it. When air passes over the coils it is cooled down. (In other words the liquid inside the coil has absorbed the heat from the air flowing over it, causing it to vaporize.)
The now hot liquid (actually gas) inside the coils has to be cooled. So it is carried outside to the units where another fan blows air over it, thus cooling the gas and condensing it into liquid. The now cooled liquid can yet again be sent into the room and the cycle repeats.
You have basically pumped heat from your house out to the environment.
When the doctor gives you a shot, or sometimes they rub rubbing alcohol on your arm.
Rubbing alcohol has a low evaporation point, this means that it dries quickly and turns to gas. Because of this low evaporation point, it also feels cold.
Liquids tend to try and absorb heat. By absorbing heat they can make something cool. If you get your shirt wet, it will feel cold because it’s absorbing heat from your body. Eventually the shirt will dry on it’s own, even if the water doesn’t boil. Water takes longer to dry than rubbing alcohol because it has a high evaporation point, and it also doesn’t feel as cold.
A/C uses a special material with a super low evaporation point. In the attic this liquid is pumped through metal tubes and it makes the tubes cool. Once the liquid heats up though, it’s no longer a liquid and it boils and turns to a gas.
This gas goes through a pipe to the box outside. The box outside does two three things:
1. It squeezes the gas so hard that the gas turns back into a liquid. When you squeeze a gas to make it a liquid it becomes even warmer, so now this warm gas is a hot liquid.
2. There’s a fan that blows air through the pipes that carry the hot liquid, and the hot liquid turns into normal temperature liquid.
3. The normal temperature liquid is pumped to the attic.
In the attic, the cycle repeats. The normal temperature liquid goes through a zig-zag pipe where it makes the pipe cold. In the process, the regular temperature liquid dries up and turns into a warm gas where it goes back to the outside box. There’s a fan in the attic that blows air against the cold pipes and that air then becomes cold from touching the cold pipes.
The pipes between the box outside and the box in the attic aren’t cold because they’re wrapped in a blanket. In the attic there’s no blanket so that pipe becomes cold.
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