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Unformatted text preview: etermine the total
entropy generated during this process, in Btu/R. cen54261_ch07.qxd 11/18/03 9:58 AM Page 343 343
CHAPTER 7 7–129E Steam enters a diffuser at 20 psia and 240°F with a
velocity of 900 ft/s and exits as saturated vapor at 240°F and
100 ft/s. The exit area of the diffuser is 1 ft2 . Determine (a) the
mass flow rate of the steam and (b) the rate of entropy generation during this process. Assume an ambient temperature
of 77°F.
7–130 Steam expands in a turbine steadily at a rate of 25,000
kg/h, entering at 8 MPa and 450°C and leaving at 50 kPa as
saturated vapor. If the power generated by the turbine is 4 MW,
determine the rate of entropy generation for this process. Assume the surrounding medium is at 25°C. Answer: 8.38 kW/K
8 MPa
450°C 7–133 A 0.4m3 rigid tank is filled with saturated liquid water
at 200°C. A valve at the bottom of the tank is now opened, and
onehalf of the total mass is withdrawn from the tank in the
liquid form. Heat is transferred to water from a source at 250°C
so that the temperature in the tank remains con...
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 Spring '09

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