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cylinder. process to be isentropic, determine the power input to the compressor for a mass flow rate of 0.02 kg/s. What would your
answer be if only one stage of compression were used?
Answers: 4.44 kW, 5.26 kW
Heat 0.4 m3
500 kPa Px 150 kPa Px
(1st stage) 900 kPa (2nd stage)
W FIGURE P7–139
7–140 One ton of liquid water at 80°C is brought into a wellinsulated and well-sealed 4-m 5-m 7-m room initially at
22°C and 100 kPa. Assuming constant specific heats for both
air and water at room temperature, determine (a) the final equilibrium temperature in the room and (b) the total entropy
change during this process, in kJ/K. 4m×5m×7m
100 kPa Water
80°C FIGURE P7–143
7–144 Consider a three-stage isentropic compressor with two
intercoolers that cool the gas to the initial temperature between
the stages. Determine the two intermediate pressures (Px and
Py) in terms of inlet and exit pressures (P1 and P2) that will
minimize the work input to the compressor.
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This document was uploaded on 11/28/2012.
- Spring '09