How is coefficient of performance different from efficiency?

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SUMMARY

The coefficient of performance (COP) differs from efficiency primarily in its definition and value range. While efficiency is the ratio of output to input and cannot exceed 1, COP, defined as Ql/W (heat removed/work done), can exceed 1 because it measures the effectiveness of heat transfer rather than energy creation. The distinction lies in the fact that COP reflects the ability to move heat rather than generate energy, which is why it is not labeled as efficiency. Understanding these concepts requires familiarity with heat pump cycles and thermodynamic principles.

PREREQUISITES
  • Understanding of thermodynamic principles
  • Familiarity with heat pump cycles
  • Knowledge of the 2nd Law of Thermodynamics
  • Basic concepts of Carnot cycles
NEXT STEPS
  • Research heat pump efficiency metrics and calculations
  • Study the 2nd Law of Thermodynamics in detail
  • Explore Carnot cycle applications in thermodynamics
  • Read "Thermodynamics" by Cengel and Boles for in-depth understanding
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Students and professionals in thermodynamics, mechanical engineers, and anyone involved in HVAC systems or energy efficiency analysis.

corona7w
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Efficiency is essentially the ratio of what you get to what you put in. COP also seems to represents the same thing (i.e. COP of a refrigerator is Ql / W, which is the amount of heat removed / the amount of work done to remove it). I know efficiency cannot exceed 1, but how come COP can have values greater than 1?
 
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Suggested Googling:

Heat pumps/engines
2nd Law of Thermodynamics
Carnot cycles.

The fridge isn't trying to create energy out of nothing,
just transfer it from one temperature to another.
 
COP is exactly the same thing as efficiency. (what you want/ what you pay for)

The only reason it isn't called efficiency is because it the coefficient can be higher than 1. You have to remember that the cycle isn't creating anything but shifting heat about.

That is basically the answer, however do read up on refrigerant/heat pump cycles. If you have a library available to you this stuff is in

Cengel and Boles - Thermodynamics. (University undergraduate level textbook)
 

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