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Have mass flow rate, want superficial vapour velocity

  1. Jul 6, 2015 #1
    Hi guys, quick simple question.

    Lets say I have a pipe separated into 3 sectoins (all horizontal), all have the same flow areas.

    In the first section it is all liquid water. I know the mass flow rate in this.

    In the second section the water is heated. And I can work out the steam quality here.

    In the third section there is a mixture of water and vapour. I would like to know the superficial vapour velocity in this section.


    If I know the quality, that means I know the mass flow rate of vapour, from x = mdot-vapour / mdot-total, right?

    From mdot-vapour [kg/s], could I multiply it by the specific volume [m3/kg] to get the volumetric flow rate of vapour?

    If I have the volumetric flow rate of vapour, I should be able to just get the vapour superficial velocity by dividing volumetric flow rate over flow area, right?
  2. jcsd
  3. Jul 6, 2015 #2
    It depends. What is your definition of superficial velocity?

  4. Jul 6, 2015 #3
    I don't know, are there any other meanings to Superficial Velocity than "the velocity of the phase as if it is the only phase moving through the cross section"?

    I really only need the Superficial Vapour Velocity and Superfacial Liquid Velocity and look up the values on Flow Regime tables to see what "Flow Regime" that section of the pipe is on.
  5. Jul 6, 2015 #4
    It looks like you've answered your own question.

  6. Jul 7, 2015 #5
    I've only answered my own question if what I assumed above makes sense :) Which I'm not sure of.

    I take your reply to mean that I have worked it out the proper way?
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