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the exit and the inlet levels is 10 m, determine the highest mass
flow rate of liquid water this pump can handle. Neglect the
kinetic energy change of water, and take the specific volume of
water to be 0.001 m3/kg.
7–87E Helium gas is compressed from 14 psia and 70°F
to 120 psia at a rate of 5 ft3/s. Determine the power input
to the compressor, assuming the compression process to be
(a) isentropic, (b) polytropic with n 1.2, (c) isothermal, and
(d ) ideal two-stage polytropic with n 1.2. 7–88E Reconsider Prob. 7–87E. Using EES (or other)
software, evaluate and plot the work of compression and entropy change of the helium as functions of the
polytropic exponent as it varies from 1 to 1.667. Discuss your
results. 7–89 Nitrogen gas is compressed from 80 kPa and 27°C to
480 kPa by a 10-kW compressor. Determine the mass flow rate
of nitrogen through the compressor, assuming the compression process to be (a) isentropic, (b) polytropic with n 1.3,
(c) isothermal, and (d ) ideal two-stage polytropic with n 1.3.
Answers: (a) 0.048 kg/s, (b) 0.051 kg/s, (c) 0.063 kg/s,
(d ) 0.056 kg/s 7–90 The compression stages...
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