Question: A refrigerator using R-134a refrigerant as a working fluid can be modeled using the ideal vapor-compression refrigeration cycle: a. The refrigerant starts the cycle

A refrigerator using R-134a refrigerant as a working fluid can be modeled using the ideal vapor-compression refrigeration cycle: a. The refrigerant starts the cycle as a saturated vapor with P = 0.18 MPa. What is the enthalpy and entropy of the working fluid at this state? b. The temperature and pressure of the working fluid after isentropic compression, T2 and P2, is 60 c and 1.40 MPa, respectively. What working fluid enthalpy at this state? c. If the mass flow rate of the refrigerant is 0.05 kg/s, what is the power input to the refrigerator compressor? d. After compression, the refrigerant undergoes an isobaric heat rejection step and the refrigerant is a saturated liquid at the end of this stage. What is the enthalpy of the working fluid at this state? e. What is the rate of heat rejection to the environment? f. The pressure of the refrigerant is returned to the original value in a throttling valve. What is the enthalpy of the working fluid after throttling? g. What is the temperature of the working fluid at this state? h. Finally, the working fluid can do its main job and take in heat from the refrigerated space. What is the rate of heat transfer during this evaporator process? i. What is the coefficient of performance for this refrigerator? j. Before it is powered on, the refrigerator contains air at 300K. After the refrigerator is powered on, what is the temperature of the refrigerated space (1 m of air) after 1 second assuming the space is insulated from the surrounding room? k. This cycle is designed to keep the refrigerated space at a cool temperature even though there actually is heat gain from the surrounding room. What is the rate of heat transfer out of the refrigerated space air at steady-state operation of the refrigeration system given the operating conditions above?

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