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Quick Work Flow Question

Posted: Wed Oct 28, 2009 9:36 pm
by rcman50166
Here I am sitting in my apartment at college looking at a question that I don't know how to get to the answer to. The text is very vague. I'll lay it out for you. I know the answer to be 80.4 kJ/kg. The problem states:

An Air compressor compresses 10 L of air at 120 kPa and 20*C to 1000 kPa and 300*C. Determine the flow work, in kJ/kg, required by the compressor.

Any explanation on how to get the answer would be greatly appreciated.

Posted: Wed Oct 28, 2009 11:41 pm
by AngryChauncey
Yeah the wording on that is terrible. Is it the wording you don't understand or the problem?

Posted: Thu Oct 29, 2009 12:05 am
by Technician1002
It looks like a fairly simple problem of finding the energy to compress 1 atm air to 1,000KPA and subtracting the energy in air at 120 KPA at 20C. I presume the temp increase is from heat of compression. The compressor is required to deliver this energy which is then thrown away as the air is cooled after compression, but the energy to compress it must be accounted for.