Question 15.1: For a theoretical single-stage cycle with a condenser pressu......
For a theoretical single-stage cycle with a condenser pressure of 250 psia and an evaporator pressure of 40 psia and using refrigerant 22 as the working fluid, determine the (a) COP, (b) temperature at exit to compressor, (c) temperature in condenser, and (d) temperature in evaporator.
Use the pressure–enthalpy diagram for refrigerant 22, Chart 4:
(a) COP = \frac{i_{3} – i_{1}}{i_{4} – i_{3}} = \frac{104.6 – 43.1}{125.4 – 104.6} = \frac{61.5}{20.8} = 2.96
(b) t_{4} = 168 F
(c) t_{1} = 116 F
(d) t_{2} = 2F
The COP in this case is determined almost entirely by the difference between
evaporating and condensing temperatures. For the highest COP the cycle should be operated at the lowest possible condensing temperature and the highest possible evaporating temperature.