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Flow rate through a valve

  1. May 26, 2014 #1

    Im a student and I try to design a valve connected to a tank. However I have some troubles to define the phenomena. I have a pressurized tank with air at 100 bar and I would like to know the evolution of the flow rate through the opened valve. The valve outlet is at the atmospheric pressure. If I know the maximum flow rate i'll be able to define correctly my valve. I think I can use the relation PV=nRT but I dont really know how to link it with the flow rate. I used the isentropic expansion to determine the pressure and temperature in the tank but I 'm not sure that help. I only know the flow rate will decrease with the pressure of the tank.

    Someone has an idea?

    Thanks a lot.

  2. jcsd
  3. May 28, 2014 #2
    You have one piece of the puzzle, but not the other piece. You need to determine the pressure drop/flow rate relationship for the valve. That will complete your model. Calculating this relationship from first principles is difficult because of the complex geometry of the valve flow channel. It might be better to measure the relationship. The relationship will typically be non-linear, and will also depend on how much the valve is open.

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