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Old 03-19-22, 05:49 PM   #5
jeff5may
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The puzzle piece that's missing here is the phase change. This is how a heat pump "cheats the system". Read the "heat pumps for dummies" post, it's super easy to understand and comprehend.

The key term here is the specific heat of condensation/vaporization. When compression happens, a certain amount of heat is used to move a certain mass of gas. This heat is released from the condenser at a constant mass conversion rate, and at constant temperature, determined by the condenser pressure. The gas must release this heat in order to become a liquid. So it does, and does, and does, and does... Ok now, the refrigerant is in a high pressure, condensed state. This means it's packed tightly into a shrunken state. It needs energy to be turned back into a gas.

Let's just do the easy thing here to illustrate and agree with your scenario. The carbon dioxide fire extinguisher experiment! When a co2 extinguisher is directed at a beer cooler, it freezes the beer! This is because the heat taken to vaporize the co2 is around 200 joules per gram of co2. Its normal "specific heat" is a single digit, so the escaping co2 falls to it's natural state (cold dry ice) before it can absorb enough heat to exist as a gas at low pressure. This heat is absorbed from the beer, which freezes pretty fast. Might not freeze solid, but that depends on the beer's phase change heat capacity.

So you see, it would take many hundreds of times as much mass of a gas following the ideal gas law to draw out as much heat as a single vessel of liquid CO2 fire extinguisher. Same principle with phase change refrigeration. The compression doesn't magically manufacture heat flow, it's the phase change of the refrigerant that absorbs and releases the massive energy.
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