Refrigerator Heat Pump Cycle (2D)

Compressor

Compressor speed 55%

Temperatures

Evaporator temp -10 °C

Condenser temp 35 °C

Refrigerant circulating — steady state.

Live Readout

COP (cooling)

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Work input

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Heat absorbed

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Heat rejected

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How it works

A vapor-compression refrigeration cycle moves heat from a cold space to a warm one by cycling a refrigerant through four stages. In the evaporator, cold low-pressure liquid refrigerant absorbs heat from the cold space and boils into vapor. The compressor then squeezes that vapor, raising both its pressure and temperature well above the surroundings. In the condenser, the hot high-pressure vapor rejects that heat to the warm space and condenses back to liquid. Finally the expansion valve drops the pressure suddenly, flashing part of the liquid to vapor and cooling the mix back down before it re-enters the evaporator.

Coefficient of performance (COP) for cooling is the ratio of heat absorbed at the cold side to the work the compressor puts in: COP = Q_c / W. Energy is always conserved, so the heat rejected at the condenser equals the heat absorbed plus the compressor's work: Q_h = Q_c + W. The theoretical ceiling is the Carnot COP, T_c/(T_h-T_c) in kelvin — narrowing the gap between evaporator and condenser temperature raises COP, which is why real systems run most efficiently on a mild day rather than a scorching one.