Open vs. Closed Refrigeration – Short 102
In this short podcast episode, Bryan explains the differences between open vs. closed refrigeration. He also explains applications for each.
When thinking about open vs. closed refrigeration, the main thing to consider is whether matter stays within the system or leaves it. (An open compressor has a motor external to the compressor and does NOT necessarily indicate an open refrigeration system.)
Open refrigeration systems result in a product that leaves the system, so they consistently need us to fill them with more matter. If a change of state occurs, it results in a product that must leave the system. So, you have to keep adding new matter and molecules to replenish molecules that were there before. You may notice something similar when grilling with propane: the propane tank gets colder as molecules leave it, which indicates that energy transfer is happening AND that matter is leaving the system. Any system that uses adiabatic cooling (swamp coolers) or consumables (ice machines) is an open refrigeration system; molecules can leave the system.
Closed refrigeration systems keep matter inside the system. Most standard compression-refrigeration A/C systems [should] keep refrigerant in the system at all times; the matter doesn't need to be replenished. (Leaky systems are faulty, not good examples of open refrigeration.)
If we begin using water or dry ice more often in refrigeration, we may begin taking advantage of more open or partially open systems. John Gorrie's original ice machine was an open refrigeration system (albeit a single-phase one where he compressed and decompressed air). We currently use closed refrigeration systems for compression-refrigeration because refrigerant is expensive and not good for the environment; recycling makes a lot more sense in that case.
Learn more about Refrigeration Technologies HERE.