An ideal heat pump has power consumption of 1000W. The temperature inside the ho

ID: 1617229 • Letter: A

Question

An ideal heat pump has power consumption of 1000W. The temperature inside the house is +20°C, while the outside temperature is -10°C.

a) How much electric energy does the pump consume in one minute?

b) How much heat does the pump provide to the house in one minute?

c) How much heat does the pump extract from outside in one minute?

d) What is the change of entropy of the house in one minute? Is the entropy change of the house positive or negative?

e) What is the change of entropy of the universe in one minute?

a) power consumption = 1000W = 1000 J/s

electric energy consumed per second = 1000 J

electric energy consumed in 1 min = 1000*60 = 60000 J

b) work done in 1 min (W)= 60000 J

QH/W = TH/(TH-TC)

=> QH/60000 = 293/(293-263)

=> QH = 586000 J

c)W = QH - QC

=> 60000 = 586000 - QC

=> QC = 580000 J

d) S = Q/T

SH = QH/TH = 586000/293 = 2000

entropy change of house is positive

e) Suniverse = QC/TC = 580000/263 = 2205.32

entropy change of universe is negative

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