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Unformatted text preview: stant. Determine
(a) the amount of heat transfer and (b) the total entropy generation for this process.
7–134E An iron block of unknown mass at 185°F is dropped
into an insulated tank that contains 0.8 ft3 of water at 70°F.
At the same time, a paddle wheel driven by a 200W motor is
activated to stir the water. Thermal equilibrium is established
after 10 min with a final temperature of 75°F. Determine the
mass of the iron block and the entropy generated during this
process.
7–135E Air enters a compressor at ambient conditions of
15 psia and 60°F with a low velocity and exits at 150 psia,
620°F, and 350 ft/s. The compressor is cooled by the ambient
air at 60°F at a rate of 1500 Btu/min. The power input to the
compressor is 400 hp. Determine (a) the mass flow rate of air
and (b) the rate of entropy generation. STEAM
TURBINE
4 MW 7–136 Steam enters an adiabatic nozzle at 3 MPa and 400°C
with a velocity of 70 m/s and exits at 2 MPa and 320 m/s. If the
nozzle has an inlet area of 7 cm2, determine (a) the exit temperature and (b) the rate of entropy generation for this process. 50...
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 Spring '09

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