Refrigeration does not destroy heat. It carries heat from the cold room to a warmer place where the condenser can release it.
In short: evaporator absorbs, compressor drives, condenser releases, expansion device reduces pressure.
The vapour-compression cycle
Every cold room — whatever its refrigerant or layout — runs the same vapour-compression cycle. A refrigerant circulates through four components, changing between liquid and gas to carry heat from inside to outside.
| Component | Location | What it does | Refrigerant state in → out |
|---|---|---|---|
| Compressor | Outside (condensing unit) | Raises refrigerant pressure and temperature, driving the cycle | Low-pressure gas → hot high-pressure gas |
| Condenser | Outside | Rejects heat to ambient air; fans accelerate the transfer | Hot gas → warm liquid |
| Expansion device | At the evaporator inlet | Drops pressure sharply, which sharply drops temperature | Warm liquid → cold low-pressure liquid/vapour |
| Evaporator | Inside the cold room | Absorbs heat from room air across finned coils; a fan circulates air | Cold liquid → cool gas |
The cool gas returns to the compressor and the loop repeats.
The one fact worth remembering
The evaporator is the only part inside the room, and it is where heat is captured. Everything else — compressor, condenser, expansion valve — exists to carry that heat outside and throw it away. When you understand this, the whole machine makes sense: cold air at the evaporator coil is simply room air that has had its heat absorbed and shipped outdoors.
Selecting the architecture that runs the cycle
The cycle is universal, but how it is implemented — direct expansion, secondary loop, or natural refrigerants — and which refrigerant family runs it are engineering choices. For Frostbox installations these use the real Daikin unit families (GS, SP-O, DB-O, SAR, SAS, PC, GM-R290). For how to select the architecture and refrigerant, see Refrigeration system selection. For the unit families themselves, see Refrigeration units.
Related articles
- How Cold Rooms Work
- How insulated panels keep heat out
- Cold room heat load explained
- Refrigeration units
- Refrigeration system selection
Recommendations reflect the MTH Algor panel system and Daikin refrigeration supplied by Frostbox. For help matching a unit to your application, contact [email protected].
