An ideal vapor-compression refrigeration cycle uses R-134a as the working fluid in an air-conditioning system. The refrigerant enters the compressor as a saturated vapor at 40 °F and leaves the condenser as a saturated liquid at 130 °F. The mass flow rate of the refrigerant is 1.5 lbm/s. Calculate the following:
a. The heat transfer rate in the condenser
b. The heat transfer rate in the evaporator
Please see the attached file.
First look up the thermodynamic data in the reference:
Saturated vapor at 40oF, hg = 107.39 (Btu/lbm), sg = 0.2189 (Btu/lbmR)
Saturated liquid at 130°F, hf = 55.3 (Btu/lbm), P = 215 psia.
For an ideal cycle, across the expansion valve, there's no change in enthalpy, so ...
The solution provides diagram, explanations, calculations and discussion for the refrigeration problem.
Maintaining a Large Refrigeration Plant
A large refrigeration plant is to be maintained at -15C, and it requires refrigeration at a rate of 100kW. The condenser of the plant is to be cooled by liquid water, which experiences a temperature rise of 8C as it flows over the coils of the condenser. Assuming the plant operates on the ideal vapor-compression cycle using refrigerant 134-a between the pressure limits of 120 and 700 kPa, determine
1. The mass flow rate of refrigerant
2. The power input to the compressor
3. The mass flow rate of the cooling water
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