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Walt Muller December 8, 2000 16:55

Air Volume Change with Pressure
I have a simple question. All the text books and websites seem to deal with far more complex issues, so I can't find the simple answer.

If I take a cubic inch of air and compress it at 120 psi, what is the resulting volume? Delta T is zero for this case. Simple as that. Any takers?


Walt Muller

John C. Chien December 10, 2000 05:51

Re: Air Volume Change with Pressure
(1). Why not check out a book on "Engineering thermodynamics" or books on IC engine thermodynamics. (2). On the p-v diagram, it is an iso-thermal compression from (p1,v1) to (p2,v2).

Walt Muller December 11, 2000 10:24

Re: Air Volume Change with Pressure
Thanks John I'll try the thermodynamics texts.

Walt Muller

Rich E December 12, 2000 08:09

Re: Air Volume Change with Pressure
The property you need to find (in an enginnering handbook) is the compressibility of air. There are two values, the isothermal compressibility and the isentropic compressibility depending on the process. They are defined as

tau = -(1/v) x (dv/dp)

so you know dp (change in pressure) you know v (initial volume) hence dv (change in volume)

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