Linear driving force model for fixed bed adsorption

Jmaes · September 4, 2023, 08:02

Hello everyone!

I am trying to use the linear driving force model to model fixed bed adsorption. I wrote a UDF for ansys fluent but upon monitoring the values, they are bonkers! The values are in the order of 10^32!

A little background on Linear driving force model:
The equation is dq/dt = k(q* - q) where q is the amount of contaminant adsorbed, k is a constant and q* is the equilibrium amount of contaminant adsorbed. q* is given by Langmuir equation q* = KL*qm*C/(1 + KL*C) where KL and qm are constants and C is the concentration of contaminant in the water. LDF model can then be applied as a source term as - (1 - eta)*rho*dq/dt to calculate adsorption, and that's what I have done.

Can someone please take a look at my code and see if there's a logical issue?

tarciwl · July 4, 2024, 12:21

I'm working on the same problem. I found an article that solved this problem, if it helps, but I still not making it work properly. I think that's because the fluent species transport equation is for mass fraction, not Molar concentration. So we probably need to convert the source term units.
Here's the article link:
https://www.sciencedirect.com/scienc...75389212001617

Jmaes · July 4, 2024, 13:01

Hello mate,

It was for my thesis and I finished it in the october last year. Anyway, I am sending you the link to my code. However, it is not verified since the experimental data was flawed due to the lack of proper measurement tools.

The C code is for ansys fluent. And it includes tons of comments and stuff so that you can understand the code if you are absolutely new (I did it to make myself understand while I was writing it and not for you lol).

Make it worth mate.

https://mega.nz/file/to1FnLLD#VsstcN...gXYhVCDY_rP-94

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July 4, 2024, 12:21		#2
tarciwl New Member Tarcisio Leal Join Date: Jan 2024 Posts: 1 Rep Power: 0	I'm working on the same problem. I found an article that solved this problem, if it helps, but I still not making it work properly. I think that's because the fluent species transport equation is for mass fraction, not Molar concentration. So we probably need to convert the source term units. Here's the article link: https://www.sciencedirect.com/scienc...75389212001617

July 4, 2024, 13:01		#3
Jmaes New Member James Ranawadia Join Date: Apr 2023 Posts: 15 Rep Power: 3	Hello mate, It was for my thesis and I finished it in the october last year. Anyway, I am sending you the link to my code. However, it is not verified since the experimental data was flawed due to the lack of proper measurement tools. The C code is for ansys fluent. And it includes tons of comments and stuff so that you can understand the code if you are absolutely new (I did it to make myself understand while I was writing it and not for you lol). Make it worth mate. https://mega.nz/file/to1FnLLD#VsstcN...gXYhVCDY_rP-94