Concept explainers
2 kg of Refrigerant-134a contained in a piston-cylinder device undergoes a reversed Carnot cycle.
Some important information about the cycle is:
● At the beginning of the adiabatic compression (State 1), the refrigerant is a saturated vapor.
● The adiabatic compression ends when the temperature of the refrigerant is 30degrees C
● The refrigerant is 50% vapor by mass at the end of the isothermal heat rejection process.
● The adiabatic expansion process ends when the pressure of the refrigerant is 132.82kPa
Consulting example 7-6 in your text might be helpful in understanding some aspects of this
problem.
c) Determine the heat transfer and work associated with each process of this reversed Carnot
cycle.
d) Determine the COP of this cycle if the piston-cylinder is being used as a heat pump.
Perform your calculation two ways:
i. Taking advantage of the fact that this is a Carnot-like device.
ii. Using the definition of COPHP that can be applied to any heat pump.
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