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Topic: Air/Liquid. Partition of hydrogen  (Read 4010 times)

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Offline beaver

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Air/Liquid. Partition of hydrogen
« on: November 10, 2007, 08:50:58 AM »
My question relate to liquid/gas partition under varying pressure and temperature condition inside a close vessel.

I have a close vessel filled with air.  Then we filled it with oil letting the air escape to atmosphere, so the air is not compressed at the end of the filling process.  The oil contains a certain concentration of hydrogen.

Air is bubbled through the oil to help achieve equilibrium.

Knowing that the Oswald coefficient is about .05, the Hydrogen will part between oil and gas in a 1:20 ratio. Therefor the hydrogen will part between oil and gas according to:

H2_gas = =H2_Initial_conc/(Oswald_H2 + (gas_vol/oil_vol))

Where,
H2_gas: final concentration in gas space
H2_initial_conc: initial concentration of hydrogen dissolved in oil
Oswald: partition coefficient = 0.05, not affected by pressure or temperature or very little. So assumed constant for this problem
Gas_vol: gas volume in vessel
Oil_vol: oil volume in vessel

My question is, if I reduce the pressure inside the close vessel, before the hydrogen start to migrate from the oil to the gas space, will that change the final concentration of hydrogen from what it would be at 1 atm.?  Will the final concentration change with temperature?

Best regards

Michel

Offline beaver

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Re: Air/Liquid. Partition of hydrogen
« Reply #1 on: November 12, 2007, 08:19:33 AM »
As a complement to my previous post, I have:

Does the vessel pressure (where the bubbling take place), and temperature modify the partition equation?

Knowing that all the hydrogen was in the liquid phase (oil), and none were in gas phase.

C0 / cgas(e) = kP + (Vgas/Voil)comp

 
Where:

  kP = Partition coefficient (or Oswald coefficient)

  C0 = Initial H2 concentration in oil

  cgas(e) = Equilibrium (final) H2 concentration in gas
  Where  (Vgas/Voil)comp  is corrected for temperature and pressure ((Vgas/Voil)*(P/PN)*(TN/T)) ?

Where:

  T = Temperature in K

  TN = 293.15 K

  P = Pressure in kPa
  PN = 101.325 kPa

Note: Oswald coefficient for hydrogen under varying pressure and temperature stays relatively constant.

So,

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