Thermodynamics

circulating water through the compressor casing. The volumeflow rate of the air at the inlet conditions is 5000 ft 3 /min, andthe power input to the compressor is 700 hp. Determine(a) the mass flow rate of the air and (b) the temperature at thecompressor exit. Answers: (a) 6.36 lbm/s, (b) 801 R5–59E Reconsider Prob. 5–58E. Using EES (or other)software, investigate the effect of the rate ofcooling of the compressor on the exit temperature of air. Letthe cooling rate vary from 0 to 100 Btu/lbm. Plot the air exittemperature against the rate of cooling, and discuss the results.5–60 Helium is to be compressed from 120 kPa and 310 Kto 700 kPa and 430 K. A heat loss of 20 kJ/kg occurs duringthe compression process. Neglecting kinetic energy changes,determine the power input required for a mass flow rate of90 kg/min.5–61 Carbon dioxide enters an adiabatic compressor at 100kPa and 300 K at a rate of 0.5 kg/s and leaves at 600 kPa and450 K. Neglecting kinetic energy changes, determine (a) thevolume flow rate of the carbon dioxide at the compressorinlet and (b) the power input to the compressor.Answers: (a) 0.28 m 3 /s, (b) 68.8 kWThrottling Valves20 kJ/kgHem· = 90 kg/minP 1 = 120 kPaT 1 = 310 KP 2 = 700 kPaT 2 = 430 KFIGURE P5–60·W in5–62C Why are throttling devices commonly used in refrigerationand air-conditioning applications?5–63C During a throttling process, the temperature of afluid drops from 30 to 20°C. Can this process occur adiabatically?5–64C Would you expect the temperature of air to drop asit undergoes a steady-flow throttling process? Explain.5–65C Would you expect the temperature of a liquid tochange as it is throttled? Explain.Chapter 5 | 2615–66 Refrigerant-134a is throttled from the saturated liquidstate at 700 kPa to a pressure of 160 kPa. Determine the temperaturedrop during this process and the final specific volumeof the refrigerant. Answers: 42.3°C, 0.0344 m 3 /kgR-134aP 1 = 700 kPaSat. liquidP 2 = 160 kPaFIGURE P5–665–67 Refrigerant-134a at 800 kPa and 25°C is throttledto a temperature of 20°C. Determine thepressure and the internal energy of the refrigerant at the finalstate. Answers: 133 kPa, 80.7 kJ/kg5–68 A well-insulated valve is used to throttle steam from 8MPa and 500°C to 6 MPa. Determine the final temperature ofthe steam. Answer: 490.1°C5–69 Reconsider Prob. 5–68. Using EES (or other)software, investigate the effect of the exit pressureof steam on the exit temperature after throttling. Let theexit pressure vary from 6 to 1 MPa. Plot the exit temperatureof steam against the exit pressure, and discuss the results.5–70E Air at 200 psia and 90°F is throttled to the atmosphericpressure of 14.7 psia. Determine the final temperatureof the air.5–71 Carbon dioxide gas enters a throttling valve at 5 MPaand 100°C and leaves at 100 kPa. Determine the temperaturechange during this process if CO 2 is assumed to be (a) anideal gas and (b) a real gas.CO 25 MPa100°CFIGURE P5–71Mixing Chambers and Heat Exchangers100 kPa5–72C When two fluid streams are mixed in a mixingchamber, can the mixture temperature be lower than the temperatureof both streams? Explain.5–73C Consider a steady-flow mixing process. Under whatconditions will the energy transported into the control volume