Question

What are the steps through which a refrigerant goes in one complete cycle of refrigeration?

Answer 1

The following processes are carried out by the liquid refrigerant, such as fluorinated hydrocarbon, during a full refrigeration cycle:

1. The fluid passes through a nozzle and expands into a low-pressure area. Similar to the way carbon dioxide comes out of a fire extinguisher and cools down, the fluid turns into a gas and cools down. This is essentially an adiabatic expansion.
2. The cool gas is in thermal contact with the inner compartment of the fridge. It heats up as heat is transferred to it from the contents of the fridge. This takes place at constant pressure, so it's an isobaric expansion.
3. The gas is transferred to a compressor, which does most of the work in this process. The gas is compressed adiabatically, heating it and turning it back into a liquid.
4. The hot liquid passes through coils on the outside of the fridge, and heat is transferred to the atmosphere. This is an isobaric compression process.

The compressor is driven by an external energy source and it does the work on the working substance during each cycle.