Compressible air flow into chamber over tube and valve

[pjer]

Hello together,

I'm trying to calculate the mass flow of air out of a chamber and also back into it. It works well for the outflow, but not for the inflow.
I prepared and attached a pdf that shows the problem and the derivation of equations used. I hope you can well understand the problem and help with your comments.


Thank you,
pjer

 

[israelkk]

Is this s homework problem?

 

[pjer]

No, its an engineering problem at work.

 

[israelkk]

What are the high and low pressures and temperatures? Are there requirements for actuator movement time to both directions and the loads.

Why are you discharging the cylinder to a volume?

 

[LittleInch]

Seems to be an incredibly complex method for determining the pressure drop across a tube...

I think the error is for phase 2 where you seem to be trying to do the reverse of Phase 1, but in fact it is the same thing as Phase 1, only with different pressures and volumes.

I think in essence what is happening is that you're blowing air from high pressure into the actuator, but "sucking" the low pressure chamber from the actuator.

I've read this a couple of time now and think this is not the way to do it.

I don't understand what temperature has to do with this - all rather opaque at the moment, at least to me....






Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Latexman]

Solve for T2 in Phase 1, then switch the subscripts on Eq. 5, and plug and chug!

Good luck,
Latexman

To a ChE, the glass is always full - 1/2 air and 1/2 water.

 

[rotw]

There is an error in the formula for phase 2, as you put (1-P2/P1)^((1-n)/n) while it should be ( 1-(P2/P1)^((1-n)/n) ) but it seems you did not carry over the error in the rest of the calc. - so it is a note just for consistency (while I am not endorsing the method ; problem is not clear yet to me).

Seems to me strange that Cp for instance has the same value in the tube and in the chambers as for real gas it is dependent upon gas conditions.