ME 235 Winter 2013
Final Exam Solutions, Section 001 (Siegel)
1. A power plant for a polar expedition operates via a Rankine cycle and uses ammonia as the
working fluid. In the boiler of the plant the ammonia is heated to 80 C at a pressure of 1000
kPa. The condenser is maintained at -15 C.
a. After passing through the boiler, determine whether the ammonia is saturated or
superheated vapor
b. Find the specific work done by the turbine, w
T
c. Find the specific work done by the pump, w P
d. What is the thermal efficiency, η, of the cycle?
2. A diesel engine has a compression ration of 20:1 with an inlet state of 95 kPa, 290 K, and
volume of 0.5 L. The cycle has a maximum temperature of 1800 K. Find:
a. The maximum pressure occurring during the cycle
b. The net specific work done by the cycle, w net
c. The thermal efficiency of the cycle, η
3. A balloon, which is initially empty, is filled with air from a line at 200 kPa, 300K. When
filled, the balloon contains 0.1 kg of air at 110 kPa, 300K. Assume the pressure of the air in
the balloon is proportional to the balloon volume, P = 100 kPa + CV, and that the ambient
temperature, T amb = 300K. Find:
a. The final volume of the balloon, V 2
b. The work done in filling the balloon, W1 2
c. The heat transfer to/from the balloon
d. The total entropy generation, S1 2,gen !!"!#$
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