A heat pump is used to keep a house warm at 22C. C A. How much work is required
ID: 1998524 • Letter: A
Question
A heat pump is used to keep a house warm at 22C. C A. How much work is required of the pump to deliver 2500 J of heat into the house if the outdoor temperature is 0C . Assume a COP of 3.0 B.How much work is required of the pump to deliver 2500 J of heat into the house if the outdoor temperature is -15C ? Assume a COP of 3.0 C. How much work is required of the pump to deliver 2500 J of heat into the house if the outdoor temperature is 0C . Assume an ideal (Carnot) coefficient of performance COP = TH/(THTL) . D. How much work is required of the pump to deliver 2500 J of heat into the house if the outdoor temperature is -15C . Assume an ideal (Carnot) coefficient of performance COP = TH/(THTL
Explanation / Answer
Hot temperature T = 22 o C = 22 + 273 = 295 K
Cold temperature T '= 0 o C = 273 K
COP = 3
heat deliver Q = 2500 J
We know COP = Q/ W
Work W = Q /COP
= 2500 / 3
= 833.33 J
(B). in this case also W = 833.33 J
(C) . COP = T /(T - T ' )
= 295/(295-273)
= 13.409
COP = Q / W '
From this W ' = Q / COP
= 2500 / 13.409
= 186.44 J
(D).
COP = T /(T - T ' ) Where T ' = -15 o C = -15 + 273 = 258 K
= 295/(295-258)
= 7.972
COP = Q / W "
From this W " = Q / COP
= 2500 / 7.972
= 313.55 J