Chapter 9, Problem 74EP

Dry atmospheric air enters an adiabatic compressor at a 20°C, 1 atm and a mass flow rate of 0.3kg/s. The air is compressed to 1 MPa. The exhaust temperature of the air is 70 degrees hottercompared to the exhaust of an isentropic compression.Determine,a. The exhaust temperature of the air (°C)b. The volumetric flow rate (L/s) at the inlet and exhaust of the compressorc. The power required to accomplish the compression (kW)d. The isentropic efficiency of the compressore. An accounting of the exergy entering the compressor (complete Table P3.9) assuming that thedead state is the same as State 1 (dry atmospheric air)f. The exergetic efficiency of the compressor

A heat pump is operating between a low temperature reservoir of 270 K and a high temperaturereservoir of 340 K. The heat pump receives heat at 255 K from the low temperature reservoir andrejects heat at 355 K to the high temperature reservoir. The heating coefficient of performance ofthe heat pump is 3.2. The heat transfer rate from the low temperature reservoir is 30 kW. The deadstate temperature is 270 K. Determine,a. Power input to the heat pump (kW)b. Heat transfer rate to the high-temperature reservoir (kW)c. Exergy destruction rate associated with the low temperature heat transfer (kW)d. Exergy destruction rate of the heat pump (kW)e. Exergy destruction rate associated with the high temperature heat transfer (kW)f. Exergetic efficiency of the heat pump itself

Refrigerant 134a (Table B6, p514 of textbook) enters a tube in the evaporator of a refrigerationsystem at 132.73 kPa and a quality of 0.15 at a velocity of 0.5 m/s. The R134a exits the tube as asaturated vapor at −21°C. The tube has an inside diameter of 3.88 cm. Determine the following,a. The pressure drop of the R134a as it flows through the tube (kPa)b. The volumetric flow rate at the inlet of the tube (L/s)c. The mass flow rate of the refrigerant through the tube (g/s)d. The volumetric flow rate at the exit of the tube (L/s)e. The velocity of the refrigerant at the exit of the tube (m/s)f. The heat transfer rate to the refrigerant (kW) as it flows through the tube