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Multiphase Reacting Modell

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Old   November 20, 2020, 15:27
Default Multiphase Reacting Modell
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Hello together,

I am currently sitting in front of the construction of my simulation. I have everything ready:
1. tables with temperature and partly pressure dependent material properties.
2. my mesh is very good.
3. the models are now ready:
My problem is that I have a reactor with a fixed bed. I wanted to simulate it pseudo-homogeneous and 2d axis-symmetric. My reaction looks like this
A(g) + B(g) --> C(g) + D(l).
If I now select a multiphase model (no matter which), I can say that a reaction takes place, but only gas to gas or liquid to liquid.
My thought: I simulate with Multicomponent GasModel but implement my substances, which are liquid, with the properties of the liquid phase.

Or is there any way to select a model so that I have two phases and gas reacts to gas and liquid? Of course I have a catalytic reaction and the reaction takes place in the gas phase on the surface. Nevertheless, the substance is present in bulk as a liquid.

Perhaps someone already has experience in this field?

Best reagrds.


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Old   November 22, 2020, 19:29
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cwl
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First of all, it depends on the behaviour of liquid phase - is it film-like or dispersed droplets in the gas phase?
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Old   November 23, 2020, 11:48
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.................
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Old   November 24, 2020, 12:12
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Quote:
Originally Posted by cwl View Post
First of all, it depends on the behaviour of liquid phase - is it film-like or dispersed droplets in the gas phase?
Thank you for your answer. So I would like to simulate the following figure (see appendix, figure 1). I have a catalyst on which a layer of liquid is formed by the reaction. Then CO and H2 (other components are neglected) diffuse into the liquid layer and react on the catalyst surface. Then I have chosen the following models (see appendix picture 1 and picture 2).

Since the liquid phase flows vertically down a plate, I have activated the Surface Tension Force under Phase Interactions (I had simulated it before in another simulation). Of course I chose the liquid phase as primary phase.

But now I have another problem. If my reaction takes place in the liquid phase I have to select the option "Interphase Reaction". Does it come with the Phase Interaction where the Surface Tension Force is located or do I have to create a 2nd Phase Interaction (Gas - Liquid)? I would now tend towards the latter case. I now have the same problem with the Gas Dissolution.
the help function of Star CCM+ says: The Gas Dissolution model has one property, Connectivity. This property identifies the gas component that corresponds to each dissolved gas component in the liquid mixture (see appendix picture 4).
I would also include it in the Interaction Gas - Liquid phase. Only here I would like to describe that my two reactant gases "dissolve" in the liquid phase (according to Henry's law). After Star CCM+, do I now have to define my educt gases as liquid again? This makes no sense to me, because the material properties (especially Thermodynamic Polynomial Data) are impossible to get for gases (which are mostly present as gases). Maximum values for material properties at 298K etc.. I thought that I would choose my product as liquid phase, but I can also say that educt1 dissolves in my product and for educt2 I cannot choose a liquid phase. And I cannot write a field function or a user code either. There is only conectivity as a property.

Thanks again for your help

Greeting

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