Wednesday, May 10, 2006
HW #8, P#7 - Shaft Work Requirment for Single-Stage and Two-Stage Compressors - 6 pts
Air enters a two-stage compressor at 100 kPa and 27°C and is compressed to 900 kPa. The pressure ratio across each stage is the same, and the air is cooled to the initial temperature between the two stages. Assuming the compression 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?
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2 comments:
The pressure ratios are the same. P2/P1 = P3/P2 x^2=900*100
is this the corectstarting point? then apply 1st law to each P1-P2 and P-P3
Yes, the pressure ratios are the same. As a result, P2 = SQRT(P1*P3).
This is the logical starting point for the solution of this problem.
Once you know P2, you can plug in values to calculate Wcomp in kJ/kg and multiply by the mass flow rate.
Best of luck,
Dr. B
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