# Helium is now compressed in a polytropic process pv n

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Unformatted text preview: n the 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 sat. vapor 500 kPa Px 150 kPa Px 27°C AIR COMPRESSOR (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 ROOM 22°C 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. Answers:...
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## This document was uploaded on 11/28/2012.

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