[Ribes]

Good morning,
I'm trying to simulate air adsorption in a zeolite layer using the species transport model, in the inlet I specified the water mass fraction and the velocity and on the interface the zero-flux condition.
I have defined the zeolite as a porous material.
The problem is that I haven't any diffusion of the vapour in the adsorber layer.
I'm a beginner in fluent...so probably I have made a really stupid mistake...but any help would be nice.

[jas123]

Hell Ribes, I am facing the similar problem like you, I have defined silica as porous media and defined constant mass fraction at the interface wall but I can't get any adsorption into silica. Have you solved your problem in Fluent. If so, could you please share your experience how to solve this issue in Fluent. My model details are attached herewith.

[Boh]

Originally Posted by jas123

Hell Ribes, I am facing the similar problem like you, I have defined silica as porous media and defined constant mass fraction at the interface wall but I can't get any adsorption into silica. Have you solved your problem in Fluent. If so, could you please share your experience how to solve this issue in Fluent. My model details are attached herewith.

Hi, it depends on what you want to achieve with your simulation...if you want to study how the water is stored in the silica gel or just the dehumidification achieved by the air

[jas123]

Hello Boh, thanks for your reply. I just want to see the dehumidification capacity achieved by the air. For example, if the relative humidity at inlet is 80%, how much humidity can be decreased at the outlet. Currently, I do not need to study how water is stored in Silica. I am using species transport with UDF to add mass and heat source term with in silica part of my domain, (please see the attached pic.). But I can not get water vapor mass transfer through the boundary between air and silica domain. Could you please tell me how to solve this problem? I have created a mesh interface between air and silica and there are two walls at the interface, one at air side and another at silica side and constant mass fraction is defined as BC at both walls. But with this BC, Fluent can not transfer vapor through the wall. I am not sure how to overcome this issue. Could you please suggest anything. Also I found a reference paper, (http://repository.up.ac.za/bitstream...pdf?sequence=1), where they said, they had same problem and they overcome defining interior BC instead of wall. But I am not sure how they did it, since they also had two separate zone, one is air another is porous brick. If you kindly take a look into the paper and suggest me anything, it would be very helpful for me.

[ashokac7]

I don't know lot about modelling humidification of air but you can also create porous media by DEM model. For this create part injector and turn on DEM for few seconds. After than switch off the DEM solver and then solve for porous region. I think this porous region will allow vapors to pass.

[Boh]

Originally Posted by jas123

Hello Boh, thanks for your reply. I just want to see the dehumidification capacity achieved by the air. For example, if the relative humidity at inlet is 80%, how much humidity can be decreased at the outlet. Currently, I do not need to study how water is stored in Silica. I am using species transport with UDF to add mass and heat source term with in silica part of my domain, (please see the attached pic.). But I can not get water vapor mass transfer through the boundary between air and silica domain. Could you please tell me how to solve this problem? I have created a mesh interface between air and silica and there are two walls at the interface, one at air side and another at silica side and constant mass fraction is defined as BC at both walls. But with this BC, Fluent can not transfer vapor through the wall. I am not sure how to overcome this issue. Could you please suggest anything. Also I found a reference paper, (http://repository.up.ac.za/bitstream...pdf?sequence=1), where they said, they had same problem and they overcome defining interior BC instead of wall. But I am not sure how they did it, since they also had two separate zone, one is air another is porous brick. If you kindly take a look into the paper and suggest me anything, it would be very helpful for me.

I'm sorry...I can't open the link. I also just wanted to simulate the adsorption from the air side...so I just added a sink term of mass of H20 on the first cells near the air-adsorbent material based on the adsorption equation (I didn't simulate the transport of water in the adsorption material but memorized the quantity of water contained in it using a C_UDMI macro).
It isn't a very elegant solution but it worked

[jas123]

Dear Bob, thanks a lot for your suggestions and kind help. Would you please mind to share a typical file of your simulation and udf script you prepares with me? If you are interested I can also share my files and you may take a look. I have spent almost more than a month and couldn't succeeded yet. Can you please save me from this please? My email id is jubair.buet.bd@gmail.com

[elwinxavier]

Hi All, have you resolved this? I too having my porous media where species cannot pass through and absorb or desorb at the porous region.
This issue is now causing a setback in my model