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-   -   Biomass Fixed bed combustion (http://www.cfd-online.com/Forums/fluent/118374-biomass-fixed-bed-combustion.html)

Roberto Meloni May 26, 2013 09:18

Biomass Fixed bed combustion
 
Hi.
I'm trying to build up a model for the biomass combustion in a fixed bed through Fluent. I'm a little confused how to setup the pyrolisis model. I wrote an UDF to compute the gases release during the process but it doesn't run.
Moreover, I can't understand if I have to define an other UDF to introduce mass and energy within the furnace.

Can anybody help me or sharing his model? It's very important for me, please!

Kind regards.
Rob.

5超7 May 27, 2013 05:11

Quote:

Originally Posted by Roberto Meloni (Post 430102)
Hi.
I'm trying to build up a model for the biomass combustion in a fixed bed through Fluent. I'm a little confused how to setup the pyrolisis model. I wrote an UDF to compute the gases release during the process but it doesn't run.
Moreover, I can't understand if I have to define an other UDF to introduce mass and energy within the furnace.

Can anybody help me or sharing his model? It's very important for me, please!

Kind regards.
Rob.

which model did you use to represident the fixed bed ? Porous media?

Roberto Meloni May 27, 2013 05:41

1 Attachment(s)
Dear 5超7.
Thank you very much for answering.
I used the Eulerian model: the biomass has been defined as a granular phase and positioned near the velocity inlet (as represented in figure). I defined 4 different phases:
- biomass;
- dry biomass (after evaporation);
- char;
- gas mixture.

The main problem is that I can't model the formation of phases (I used the DEFINE_HET_RXN_RATE UDF). Could you help me? Am I wrong the approach?

All the best.
Roberto.

5超7 May 27, 2013 23:17

I think it is very difficult to represident fixed bed by
Euler-
Euler model. I remember this model could be used to simulate the problem of fluidized bed, not fixed bed. Porous media model could be suitable for your question,but code of your problem is very difficult to write. UDF is new to me. Sorry,I can't help very much.:(

sml July 10, 2013 07:32

Modelling wooden pellet combustion in Fluent
 
I am beginner in the field of biomass combustion and need some leads or advices. I am working on 3D modelling Pelletized furnace using Fluent. It seems in the modeling of pelletized furnace one practical way is the constructing appropriate bed model to calculates the temperature, species and velocity at the top of the fuel bed. I know that combustion modelling is a very complex phenomena and involved following process.

1-moisture evaporation model
2-3 Biomass : Volatiles (Cm Hn; CO;H 2; CO 2; O 2 . . )+ Char
4- char oxidization

I wonder if anyone could share his/her experiences and recommend some UDFs in order to build the fixed bed model for 3D combustion of small scale wooden pelletized furnace.

Best Regard
:confused:

bilalsungurr February 27, 2014 05:00

Hi roberto..i think your approach is true but i have similar problems too..maybe porous media will be appropriate choice but exactly i dont know how to use it...if you have an advice i will be happy..best regards


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