Answer to Question #266123 in Thermal Power Engineering for Deven

Question

https://www.chegg.com/homework-help/consider-carnot-heat-pump-cycle-executed-steady-flow-system-chapter-6-problem-140p-solution-9780077366742-exc

Answer 1

The question referred to is

"Consider a Carnot heat-pump cycle executed in a steady-flow system in the saturated liquid-vapor mixture region using refrigerant-134a flowing at a rate of 0.22kg/s as the working fluid. It is known that the maximum absolute temperature in the cycle is 1.2 times the minimum absolute temperature, and the net power input to the cycle is 5kW. If the refrigerant changes from saturated vapor to saturated liquid during the heat rejection process, determine the ratio of the maximum to minimum pressures in the cycle."

Solution

Coefficient of performance of heat pump

$COP_{HP}=\frac{1}{1-\frac{Q_L}{Q_H}}$

Where $Q_L=$ Minimum absolute Temperature

$Q_H=$ Maximum heat Temperature

But $Q_L=\frac{Q_H}{1-2}$

$\therefore \> COP_{HP}=\frac{1}{1-\frac{Q_H}{1.2{Q_H}}}$

$=\frac{1}{1-\frac{1}{1.2}}=6$