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Old   June 7, 2001, 22:53
Default moist air density
  #1
rafat
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Hi, I am trying to simulate a natural-draft wet cooling tower performance. I want to use a single phase simulation using Fluent 5.4 . I am trying to define the density of the moist air at the inelt. my problem is the interaction between the air and water "theoritically". I wonder if anyone has come by such a problem to help me.

I mean what sort of function should I use to express the change in the air density.

thanks for your help in advance.
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Old   June 8, 2001, 04:03
Default Re: moist air density
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Bart Prast
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If you do not include phase transition (condensation of water) you can do this by assuming a mixture of 2 ideal gases (air/water vapour): P = Pvapour + Pair with Pvapour the partial vapour pressure (saturation ratio * saturated vapour pressure)
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Old   June 8, 2001, 04:37
Default Re: moist air density
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rafat
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This has opend the door to another variable Pvabour. I am affraid I do not have enogh skill to play around with fluent. I am trying to find the way of mixing two fluid together.
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Old   June 8, 2001, 04:47
Default Re: moist air density
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Bart Prast
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If you need the density of moist air specifically (as opposed to dry air), you need the properties of the water vapour. You can also do this in terms of mass fractions.
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Old   June 12, 2001, 11:49
Default Re: moist air density
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Sergei Zhubrin
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Check out PHOENICS User Support pages at http://www.simuserve.com/cfd-shop/support.htm.

Under 'On-line CFD calculators' you will find one called 'Air-water saturation' for the estimation of some air-water saturation data .

Give it a try and look at what it says re underlying methods.

Regards

Sergei Zhubrin
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Old   June 13, 2001, 21:36
Default Re: moist air density
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rafat
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Thank you for this, I tried to run it but it send me an error in the page. I will try it later on. thnk you again.
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