A heat pump collects thermal energy from outside air at 5C and delivers it into
ID: 1591251 • Letter: A
Question
A heat pump collects thermal energy from outside air at 5C and delivers it into a house at 40C.
Determine the maximum coefficient of performance (the maximum coefficient is determined in the same way as for a thermodynamic engine).
If the motor of the heating pump uses
1000 J of electrical energy to do work during a certain time interval, how much thermal energy is delivered into the house through heating, assuming the heating pump works at the maximum coefficient of performance?
If the motor of the heating pump uses
1000 J of electrical energy to do work during a certain time interval, how much thermal energy is delivered into the house through heating, assuming the heating pump works at a coefficient of performance of 2.0.
Explanation / Answer
Here ,
Tc = 5 degree C = 278 K
Th = 40 degree C = 313 K
coefficient of performance = Th/(Th -Tc)
coefficient of performance = 313/(313 -278)
coefficient of performance = 8.94
the coefficient of performance is 8.94
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work done , W = 1000 J
as Qh/W = coefficient of performance
Qh/1000 = 8.94
QH = 8490
the heat delivered to the house is 8490 J
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coefficient of performance = 2
Qh/W = coefficient of performance
Qh/1000 = 2
Qh = 2000 J
the thermal energy delivered the room is 2000 J