Air Conditioners Move Heat
From a hot room to the outdoors
An air conditioner does not make cold air; it moves a room’s heat outdoors. Follow the refrigerant in 15 scenes as it boils in the indoor unit, gets hot in the compressor, turns liquid in the outdoor unit and gets cold again through the expansion valve.
Watch from the start in 3DChapter 1 · The heat in the room
A summer room is full of heat. Where does an air conditioner send it?
- 1 A summer room
Seeing the heat in a room as red dots
View in 3D → - 2 A machine that makes cold air?
An air conditioner moves heat instead of making cold
View in 3D → - 3 Which way heat flows
Heat flows on its own only from hot to cold
View in 3D → - 4 Refrigerant in the pipes
A substance that boils at a very low temperature travels around the pipes
View in 3D →
Chapter 2 · Indoor unit: boiling soaks up heat
Cold refrigerant boils inside the indoor unit and takes the room’s heat with it.
- 5 Soaking up heat by boiling
Cold refrigerant takes the room’s heat and boils
View in 3D → - 6 Cool air and water
Cooled air comes out, and water vapor in the air turns to water
View in 3D →
Chapter 3 · Compressor: squeeze it hot
To dump heat outdoors, the refrigerant must first be hotter than the outdoors.
- 7 It can’t dump the heat yet
Refrigerant leaving the indoor unit is colder than the outdoors
View in 3D → - 8 Squeeze it and it heats up
The compressor squeezes the refrigerant gas and makes it hot
View in 3D → - 9 What the electricity does
Electricity doesn’t make cold; it squeezes the refrigerant hot
View in 3D →
Chapter 4 · Outdoor unit: dump the heat
Hot refrigerant gives its heat to the outdoor air and turns back into a liquid.
- 10 Dumping heat outdoors
Hot refrigerant hands its heat to the outdoor air
View in 3D → - 11 Back to a liquid
At high pressure, it turns to liquid even at a high temperature
View in 3D → - 12 More heat out than in
Heat dumped = heat taken in + electricity
View in 3D →
Chapter 5 · Expansion valve: cold again
A tiny opening drops the pressure, and the refrigerant cools itself down.
- 13 A tiny opening
The pressure is very different on each side of a tiny opening
View in 3D → - 14 Refrigerant that cools itself
When the pressure drops, some of it boils and the rest cools down
View in 3D → - 15 Around and around again
1 unit of electricity moves about 4 units of heat
View in 3D →
More in the series
Temperatures, pressures and amounts of heat are calculated from property tables for the refrigerant R-32 (CoolProp). The example is a home air conditioner removing 2.5 kW of heat, with the room at 27 °C and the outdoors at 35 °C. In the 3D view, the refrigerant moves far slower than in real life, and the inside of the compressor and the expansion valve are shown as enlarged, simplified models.