High School Physics + more

How do refrigerators and air conditioners work? | work and heat flow

In this post, we will briefly discuss (1) how refrigerators work, & (2) How Air conditioners work. Work and Heat flow diagram of refrigerator and air-conditioner is also presented here.

How do Refrigerators work – in brief

Here are the steps followed in a refrigerator

  • Refrigerators work by causing the refrigerant circulating inside them to change from a liquid into a gas by evaporation.
  • To start the evaporation process and change the refrigerant from liquid to gas, the pressure on the refrigerant needs to be reduced through an outlet called the capillary tube.
  • Evaporation cools the surrounding area and produces the desired cooling effect. 
  • To keep a refrigerator running, you need to be able to get the gaseous refrigerant back to its liquid state, so the gas needs to be compressed to a higher pressure and temperature again. This is where the compressor comes in. 
  • Once the compressor has done its work, the gas should be under high pressure and hot.
  • Hence, the gas needs to be cooled in the condenser, which is mounted on the back of the refrigerator, so its contents can be cooled by the ambient air.
  • When the gas cools off inside the condenser (still under high pressure), it changes back into a liquid.
  • Then, the liquid refrigerant circulates back to the evaporator where the process starts all over again

Air conditioner function in brief

An air conditioner works in a similar way. The evaporator is in the unit inside the house and the compressor is outside. Because of the work put into the compressor heat is removed from the air inside the house and transferred to the outside air. The diagram below shows work and heat flows in a refrigerator or air conditioner.

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Work and Heat flow in refrigerator (in a diagram)

Refrigerator – work and heat flow diagram

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