Air Conditioners Move Heat
All scenes › Chapter 1 The heat in the room
Which way heat flows
Heat flows on its own only from hot to cold
View in 3DHeat goes from hot to cold
Heat always flows on its own from a hotter place to a colder one. Leave a spoon in hot soup and the spoon warms up. In summer it is hotter outdoors (35 °C) than in the room (27 °C), so heat keeps coming into the room through the walls and windows. An air conditioner has to work against this flow, moving heat from the cooler room to the hotter outdoors.
Why?The opposite never happens by itself: heat does not move on its own from a cold place to a hot one, just as water does not run uphill on its own. That is why an air conditioner uses electricity to pump the heat uphill.
Learn moreThe rule that heat flows on its own only from hot to cold is called the second law of thermodynamics. Turn the air conditioner off and the room slowly drifts back toward the outdoor temperature.
- The way heat flows on its own
- 35 → 27 °C
calculated from R-32 property tables (CoolProp) · example: room 27 °C, outdoors 35 °C
View this scene in 3D →Read more
Wikipedia: Second law of thermodynamics
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.