The contents of a refrigerator are at 5°C. The surroundings are at 20°C. Heat transfers through the walls to the inside of the refrigerator at a rate of 100 kJ/min. Consequently, the refrigeration process operates continuously at steady state, and removes 100 kJ/min of heat, thus allowing the contents to be maintained at a constant temperature of 5°C (Figure 5-11). The refrigerant is Freon® 22, and thermodynamic properties are provided in Appendix F. The material leaving the boiler is saturated vapor at 0°C and the material leaving the condenser is saturated liquid at 25°C. The compressor has an efficiency of 75%. Find the refrigerant flow rate required to remove 100 kJ/min of heat from the inside of the refrigerator, and the rate at which the compressor requires work.

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4 1 Saturated liquid T = 25°C -Low P QH Condenser Boiler Tambient = 20°C Ws,comp 3 n = 0.75 Saturated vapor T = 0°C Qc= 100 kJ/min T = 5°C FIGURE 5-11 Vapor-compression cycle described in Example 5-3. 2