Carnot COP (Refrigerator)

This formula gives the theoretical upper limit on the coefficient of performance of a refrigerator operating between a cold space at temperature Tc and a warmer environment at Th. It comes from the reversible Carnot cycle, where the best possible refrigerator moves heat from cold to hot with the least possible work input, so the COP depends only on the two absolute temperatures. Because the temperatures must be in kelvin, the result is dimensionless and shows that performance improves when the temperature lift (Th - Tc) is small.

Use this when you need the ideal benchmark for refrigeration or cooling systems, such as comparing real equipment against the thermodynamic limit. It is also useful in advanced HVAC, heat-pump, and thermodynamics problems involving reversible cycles and temperature-driven performance limits.

• Using degrees Celsius instead of kelvin
• Reversing the temperatures or using Th/Tc the wrong way around
• Treating the Carnot COP as a real machine's actual COP rather than an ideal upper limit