[amin_67323]

hello all
I think you can help me in fluent. how can i define an adsorber bed in fixed bed reactor with a multiphase flow? my bed is solid porous media with granular particles and the other phase is air plus 0.1% volume fraction pollutants.
i appreciate for your helping

[rudofly]

Hello Amin!

How are you, have you made progress finding the answer to your question?

Best regards,

Rudi

[amin_67323]

hello rudi
unfortunately i'm still working on it, but i have not any progress in defining volume fraction of materials.
thank's for your reply

[rudofly]

I would like to help you, if I can. Depending on your actual problem, I might have I ideas to solve them.

What volume fraction do struggle with?

[amin_67323]

thank you rudi,
The simulated adsorber consisted of a reactor with a 0.76 cm inner radius containing a 12 cm long fixed-bed of activated carbon with 0.75 mm mean particle diameter. A 10 liters per minute air stream containing 1000 ppmv of the VOC(acetone, benzene, toluene and 1, 2, 4-trimethylbenzene) entered from the top of the reactor at a superficial velocity (Vs) of 0.914 m/s and exited from the bottom of the reactor.
now my question is:
how to define the phase of air containing of VOC and the volume fraction of this materials?
appreciate for your helping

[amin_67323]

hello rudi,
what happened? you didn't answer my question. you can't help me?

[rudofly]

Hi Amin!

Don't worry, I was only off work for some time. I think that is okay.

I suggest that you model volatile organic compounds in air as either multiphase flow or as species with mass transport which ever will lead to better results for you.

[amin_67323]

thank you rudi, but can you explain exactly for me what options i must choose in fluent to define that?

[rudofly]

So, you are not familiar with Fluent at all? Have you been able to create a model of your domain using Design Modeler?

[amin_67323]

i have very little experience with fluent. however i modeled that but i'm not sure it's correct or not. if you help me i will appreciate that

[rudofly]

Amin, I would like to help you solve your problem. I would appreciate if you were a little more proactive. Help me to help you! How does your model look like? Have you modeled a packed bed or is it just the empty column?

If your particles are big, you can model the column by cutting a sphere for each particle out of a cylindrical column. It will be sufficient to only simulate a slice of your column. When you did the modeling part, we can define boundary conditions.

If your particles are small, they will be to many for rigid modeling. Then we should look at Fluent's rigid particle models.

[amin_67323]

i modeled a packed bed column with a 0.76 cm inner radius containing a 12 cm long of activated carbon with 0.75 mm mean particle diameter. A 10 liters per minute air stream containing 1000 ppmv of the VOC entered from the top of the reactor at a superficial velocity of 0.914 m/s and exited from the bottom of the reactor. i think the particles are small.
thank you rudi

[rudofly]

I suggest that you set the volume fraction of phase 2 equal to 0.0001 at your velocity inlet. You have to select phase 2 from the selection box that reads mixture on your boundary to do so.

Does that help you?

[amin_67323]

yes i set eulerian in multiphase model but in phase 1 when i want to set the phase materials, it accept only 1 material but my phase 1 materials are 5(acetone, benzene, toluene and 1, 2, 4-trimethylbenzene,air).

[rudofly]

Volume of fluid method supports higher numbers of immiscible phases. But then again, you could also use species transport instead of multiphase flow.

[amin_67323]

in volume of fluid option i can't set carbon as granular packed bed. i have those problems yet.

[amin_67323]

how can i set the volume fraction of phase 2 equal to 0.0001 at velocity inlet?

[rudofly]

It think it is not difficult. So, I believe you have difficulty with using Fluent. I have version 15. I made screen shots to help you.


1. Select the boundary that you want to be the inlet.
2. Change the boundary type from anything else to velocity inlet.
3. If there is a confirmation box, click yes.
4. If there is a new window open, close it.


1. Click on the Phase selection box and select phase-2.


1. Click on Edit... and change to Multiphase tab.
2. Enter your volume fraction.

[amin_67323]

hi rudi
let me explain for you what i did
it's a adsorption bed that benzene-tuloene-acetone must adsorb to carbon bed from mixture of air-benzene-tuloene-acetone. and air will export from outlet.
i set cabon as phase 2 becuase it's my granular fixed bed and if i set that as phase 1 i can't set it as granular.
Attachment 35531
and then i set air-benzene-tuloene-acetone as phase 1
Attachment 35532
Attachment 35534
now i must set the volume fraction of benzene-tuloene-acetone equal to 0.0001. but in velocity inlet the volume fraction is not working.
Attachment 35535
but it's working for phase 2 that's only carbon in phase 2 and volume fraction isn't important.

[rudofly]

Hi Amin,
I do understand better now. However I cannot display the attachments. The links I get seem to be invalid for me. Can you repair the links?