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Old   September 27, 2010, 00:40
Default volume concentration
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seok jun
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I have some queation using CFX.
Dispersion problem.
rectangle box.
initial condition : air in rectangle box
boundary condition : inlet(Hydrogen mass flow), openning


1. I can not fine volume concentration in CFX-post.
(just mass concentration, mass fraction)

2. How conversion to volume concentration.
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Old   September 27, 2010, 06:33
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Glenn Horrocks
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You can calculate it from the mass fraction and molar masses of the components. I will leave the derivation of the equation up to you from there.
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Old   September 27, 2010, 07:03
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seok jun
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Thank you for your comment.
But I don't know conversion equation.
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Old   September 27, 2010, 07:11
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http://en.wikipedia.org/wiki/Molar_volume
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Old   September 27, 2010, 07:27
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I need to Hydrogen Volume Concentration (Vol %).
(Time series value on sensor(points))

Hydrogen density : 0.09
Air density : 1.205

If the sample is a mixture containing N components, the molar volume is calculated using ~~~/

what is the Xi?
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Old   September 30, 2010, 03:42
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Matthias Voß
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hi

if V is m3/mol and M is mol what could possibly x_i be?
It is Mass_i/Total_Mass (MassFraction), and if you sum up over i components you end up in a weighted Molar Mass. This divided by the weighted Density of the Mixture is the Molar Volume.

\frac{\sum\frac{Mass_{i}}{Total_{Mass}}*\frac{Mol_{i}}{Mass_{i}}}{\frac{Total_{Mass}}{Total_{Volume}}}=\frac{\frac{Mol}{Mass}}{\frac{Mass}{Volume}}=\frac{Volume}{Mol}


neewbie

P.S.: next time i´ll find the Latex button in the beginning.

Last edited by mvoss; September 30, 2010 at 08:06.
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