Unformatted text preview: _ch07.qxd 11/18/03 9:58 AM Page 345 345
CHAPTER 7 the required mass flow rate of steam. Also, show the process on
a T-s diagram with respect to saturation lines. equal. Show that Tf
T1T2 when the heat engine produces
the maximum possible work. Answer: 82.0 kg/s 7–147 Refrigerant-134a at 140 kPa and 10°C is compressed by an adiabatic 0.5-kW compressor to an exit state of
700 kPa and 60°C. Neglecting the changes in kinetic and potential energies, determine (a) the isentropic efficiency of the
compressor, (b) the volume flow rate of the refrigerant at the
compressor inlet, in L/min, and (c) the maximum volume flow
rate at the inlet conditions that this adiabatic 0.5-kW compressor can handle without violating the second law.
7–148E Helium gas enters a nozzle whose isentropic efficiency is 94 percent with a low velocity, and it exits at 14 psia,
180°F, and 1000 ft/s. Determine the pressure and temperature
at the nozzle inlet.
7–149 An adiabatic air compressor is to be powered by
a direct-coupled adiabatic steam turbine that is
also driving a generator. St...
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