Refrigeration Fundamentals1 / 17
The Vapour-Compression Cycle
Compressor, condenser, expansion device, evaporator, refrigerant flow.
11 min read · Jacob Willis, Net Zero Lead · Last reviewed July 2026
Every fridge, freezer, chiller, air-conditioner and heat pump you will ever audit runs on the same trick: the vapour-compression cycle, a closed loop that pumps heat uphill, from somewhere cold to somewhere hot, by exploiting how a refrigerant's boiling point changes with pressure. Understand this one loop and you understand the machine behind most of a building's cooling bill and, increasingly, its heating too.
In this lesson
- 01Walk the loop
- 02The energy balance
- 03A refrigerator, concretely