Draw a complete schematic for each (show arrows, symbols & numeric values for W

ID: 1862119 • Letter: D

Question

Draw a complete schematic for each (show arrows, symbols & numeric values for W , Q_C & Q_H ).

Determine if each cycle is IRREVERSIBLE, REVERSIBLE or IMPOSSIBLE by calculating the

cycle COP and comparing to the maximum reversible COP.

a) The hot exhaust from a diesel truck engine at 100 oC is the energy source for a power cycle generating 10 kW of

electrical power to operate the climate control system for the driver. The power cycle rejects 90 kJ/s of waste

heat into the 40 oC summer atmosphere.

Actual COP = ___ vs. Reversible COP = ___

This case is? irreversible, reversible, impossible

b) A Carnot cycle refrigerator operates between 20 K and 20 oC with a cooling rate of 30 Watts and a power input of

approximately 410 Watts.

Actual COP = ___ vs. Reversible COP = ___

This case is? irreversible, reversible, impossible

c) A geo-thermal heat pump draws 20 kJ/s from +10 oC groundwater to provide 25 kJ/s of heating to a residential

building with the indoor climate controlled at 23 oC.

Actual COP = ___ vs. Reversible COP = ___

This case is? irreversible, reversible, impossible

d) A geo-thermal heat pump draws 200 kJ/s from +10 oC groundwater to provide 250 kJ/s of heating into the steam

boilers operating at 120 oC that provide winter heating for the KU campus.

Actual COP = ___ vs. Reversible COP = ___

This case is? irreversible, reversible, impossible

(b) actual COP=cooling rate /power input=Qo/Win=30/410=0.07317

reversible COP=T2/(T1-T2)=20/(293-20)=0.07326

here since actual COP is approximately same as reversible COP so process is reversible

reversible COP=T1/(T1-T2)=(23+273)/(23-10)=22.78

here we can see that actual COP is less than reversible COP so the process is irreversible

(d) actual COP=Qo/Win=250/(250-200)=5

reversible COP=T1/(T1-T2)=(120+273)/(120-10)=3.57

here we can see that actual COP is more than reversible COP so the process is impossible

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