ME 336 EXAM 2,
NOVEMBER 21, 2000
C. BORGNAKKE, ME Dept.
Problem 1 [40 Points]
The U of M power plant feeds 25 kg/s steam at 3 MPa, 500 C
to the turbine. The
condenser temperature is 35 C. Assume the plant operates one open feedwater heater at
150 kPa, where the feedwater leaves as saturated liquid.
a) Find the extraction flowrate.
b) Find the total turbine work.
Problem 2 [30 Points]
An air flow of 5 kg/min at 1500 K, 125 kPa goes through a constant pressure heat
exchanger, giving energy to a heat engine. The air exits at 500 K and the ambient is at 298
K, 100 kPa.
a) Find the energy delivered to the heat engine.
b) Find the energy the heat engine can give out.
Problem 3 [30 Points]
A flow of 1 kg/s CO2 at 1600 K, 100 kPa is mixed with a flow of 2 kg/s water at 800 K,
100 kPa and after the mixing it goes through a heat exchanger where it is cooled to 500 K
by a 400 K energy reservoir.
a) How much power (heat transfer) is taken out in the heat exchanger?
b) How much is the rate of entropy generation in the overall process.
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 Fall '09
 Borgnakke
 Energy, Entropy, Heat, Heat engine, Sgen

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