A freezer in a meat factory is kept at -10 celsius when the outside air temperat

Question

A freezer in a meat factory is kept at -10 celsius when the outside air temperature is 24 degrees celsiu. the freezer pumps heat from inside the freezer to the outside with a coefficient of performance N=0.70 the Carnot coefficient of performance.

A.) What is the actual COP of this freezer?

I use the equation.. e=Tc/(Th - Tc)

Tc / (Th-Tc) = (263 kelvin) / (298K - 263K) = 7.51

so, now i get confused....

is it, (70%)(7.51) = 5.26 ?

B.) Heat leaks into the freezer from the outside ate a rate of 500 J/s. The electric motor that drives the freezer heat pump runs continously.    --   What is the power requirement of the motor to keep the freezer at -10 Celsius?

so if the coeff. of perf. N=5.26 = Qh / W

heat coming in is Qh= 500 J

and then just solve for work? or is the work exact opposite of the heat coming in ? which is -500 J/s?

Explanation / Answer

A) you are right

B)

workdone = 500/5.26 = 95.057 J/s

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