How an AC air conditioner works?

artwork showing the basic components of an air conditioning unit and the order in which they work or not

in o general !

Warm air from the room is sucked in through a grille at the base of the machine
The air flows over some chiller pipes through which a coolant fluid is circulating. This part of the machine works just like the chiller cabinet in a refrigerator. It cools down the incoming air and a dehumidifier removes any excess moisture.
The air then flows over a heating element (similar to the one in a fan heater). On a cold day, this part of the unit may be turned right up so the HVAC works as a heater.
A fan at the top blasts the air back through another grille into the room. If the heating element is turned down, the air re-entering the room is much cooler, so the room gradually cools down.
Meanwhile, coolant (a volatile liquid that evaporates easily) flows through the chiller pipes. As it does so, it picks up heat from the air blowing past the pipes and evaporates, turning from a cool liquid into a hotter gas. It carries this heat from inside the room to the outside of the building, where it gives up its heat to the outside air. How? Just like in a refrigerator, the coolant flows through a compressor unit and some condensing pipes, which turn it back into a cool liquid ready to cycle round the loop again.
What happens to the heat? In the unit outside the building, there are lots of metal plates that dissipate the heat to the atmosphere. An electric fan blows air past them to accelerate the process.
Over time, the heat inside the building gradually pumps away into the outside air.
Daikin air conditioner: front view Daikin air conditioner: side view and closeup of heat dissipating metal plates
Photos: Where does the heat go? Look around the side of an air conditioner like this and you’ll see it’s jam-packed with metal, heat-dissipating plates. You may even feel some heat being given off as the fan sucks or blows air past them. The image on the right is a close-up of the black area outlined in the middle photo.

How air conditioners can harm the environment
Hole in the ozone layer 1998. Picture by NASA

Photo: The ozone hole over Antarctica that was caused by CFC pollution, mostly from air conditioners, refrigerators, and aerosols. Picture courtesy of NASA on the Commons.

You probably love the feel of freshly chilled air on a hot day, but don’t forget that law called the conservation of energy! There’s always a price to pay for getting something good in our universe. In this case, the price is the energy you have to use to run the air conditioning unit; using energy means there’s an impact on your pocket and on the planet too in the shape of environmental problems like global warming. Environmentalists say we should use less air-conditioning, which sounds easier than it is in a really hot climate. It’s important to remember that air-conditioning isn’t just about luxury or comfort: an air-conditioned room can make you much more productive at work and it can have important health benefits too; some public-health doctors have suggested that the greater use of air conditioning in the United States is one reason why there are fewer heat-related deaths there than in Europe, where air conditioning is used less. It’s sometimes argued that if people don’t have air conditioning, they’re more likely to use things like electric fans, which work very inefficiently (rearranging hot air instead of removing it and generating heat with their own electric motors). But the biggest electric desk fans (typically rated 25–50 watts) use a fraction as much electricity as the smallest air conditioners (typically rated at 750–1000 watts); you could use about 20–30 fans and consume the same or less power than a compact AC unit!

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