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 Neser February 22, 2005 10:00

spray an aqueous solution

I want to spray an aqueous solution containing 20% (by weight) Sodium Chloride concentration. The spray droplets will entrain into hot air. Therefore, an amount of water vapour will evaporate from the droplets and consequently the sodium chloride concentration will increase.

I created the sodium chloride aqueous solution as a variable composition liquid consisting of sodium chloride and water. Actually the properties of the solution depend on temperature and NaCl concentration. Now:

1. I cannot define Sodium chloride as a solid. This is because CFX cannot mix solid + liquid to create this mixture described above. 2. I cannot create a 'reaction' between solid and liquid. This is because CFX does not have the capability. 3. If I define the NaCl simply as a liquid at any random concentration, and then define the mixture's (i.e. NaCl +water) density as a function of temperature and concentration, CFX solver refuses. The solver requests the value of the concentration, even though I previously defined mass fraction of water and NaCl for boundary conditions. 4. If I decide to provide CFX with the concentration of the NaCl (as it requested) as, say 30%, and then define the boundary condition mass fractions of NaCl-Water as, say 20%-80%, there is a problem. The problem is that the resulting total concentration is now wrong because the initial concentration is 30%. In fact, the resulting concentration will be an unknown somewhere between 30-? %.

Any help would be most appreciated

 caty February 22, 2005 20:19

Re: spray an aqueous solution

Hi Neser,

I am a beginner is CFX but i would sugest to use the eulerian - lagrangian model instead of Euler - Euler. You can create than a mixture between water and air as continous phase and track the solid and water droplet particles using the particle tracking.(in this case you dont need to specify the volume fractions)

In fact i dont understand exactely who with whom is reacting in your case...

caty

 Neser February 22, 2005 20:53

Re: spray an aqueous solution

Hi, Caty thank you for your reply. The solid Sodium Chloride is disolved in the water to create an aqueous solution. Therefore, I have not solid and water (i.e. two phase).

about the reaction, a hot water will react with the water vapour in the solution and then water will be evaporated from the solution. This means the concentration of the dissolved solid will increase

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