# MERM App.24F air table



## dpolet (Feb 11, 2013)

I found App24F and direct isentropical equation will generate different results. Which one will be used? For example, Linderburg 500 practice problem 29-1. I get result of 1319R using equation. the solution is 1375R using air table. Did I do anything wrong? Thanks.


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## ongreystreet (Feb 12, 2013)

Lindeburg provides the solutions, don't over think it.


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## CRNewsom (Feb 12, 2013)

Did you account for the change in density of the gas? For liquids, this may be negligible, but not for air.


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## dpolet (Feb 12, 2013)

Here is the detailed data

Air expands isentropically from point 1 to point 2

P1=200 psia T1=1960R

P2=50 psia T2=?

using the equation of isentropical process

(P2/P1)=(T2/T1)^(k/k-1)

k=1.4 for air. T2 can be calculated to 1319R

Did I do anything wrong on this calculation? Thank you.


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## CRNewsom (Feb 13, 2013)

I can't see any errors in your calculation. Check on PPI's website for the errata for your edition and printing of the book. A search of the first printing of the 12th edition yielded many results.


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