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Q10. A heat pump with refrigerant-134a (R-134a) as the working fluid is used to keep a space at 22 °C by absorbing heat from geothermal water that enters the evaporator at Twater - 60 °C at a rate of 0.061 kg/s and leaves at Tawater - 40 °C. The specific heat of liquid water is 4.18 kJ/(kg-K). Refrigerant enters the evaporator at TR-134a = 10 °C with a quality of x - 11 % and leaves at the same pressure as saturated R-134a vapor at the same temperature. The compressor consumes 1.3 kW of power. For this problem you must use property tables (from the textbook). Determine the ideal minimum power input (in kW) to the compressor for the same rate of heat supply.
Q12. Steam expands in a turbine steadily at a mass flowrate of th = 40 Mg/h, entering at 8 MPa, 500°C and 85 m/s, and leaving at 40 kPa, 88% quality and 47 m/s. If the power generated by the turbine is 7.2 MW and the surrounding has a constant temperature of 26 °C For this problem you must use property tables (from the textbook). Determine the turbine inlet area (in cm2).