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-   -   Modeling question: coal combustion (http://www.cfd-online.com/Forums/fluent/42116-modeling-question-coal-combustion.html)

 Pablo Sanchez August 23, 2006 07:48

Modeling question: coal combustion

Hi,

I am modeling the heat transfer in a barbeque grill using charcoal as the fuel. I am using a layer of porous media to model the charcoal, and am looking for some reasonable values for viscous and inertial resistances and for the energy source term.

If anyone has experience from modeling coal combustion, where the air passes through a bed of coal, I would be very interested in hearing how this was modeled. Thank you in advance for any pointers you can provide.

Regards,

Pablo

 san August 23, 2006 23:41

Re: Modeling question: coal combustion

hi, i am looking for such type of problems.

There is an Example file in Fluent for pre-mixed , non-premixed type of combustion model.

I hope this may help you.

Bye san

 Allan Walsh August 24, 2006 13:17

Re: Modeling question: coal combustion

For a simple model (do you have a layer of charcoal or a pile) I would adjust the viscous and porous terms to get a pressure loss of about 1 inch of water column per foot of charcoal depth - you may have to convert to your own units.

For the energy source, coal yields about 12,000 Btu/lb. Say the charcoal burns for 1.5 hours, you can calculate the energy source depending on how many pounds of charcoal you use. (Or, look at the volume of your porous region multiplied by the density).

Are you actually modeling charcoal? or briquettes? Since briquettes have a faily uniform size and shape, it would be quite easy to model them as discrete units. They could be set up to generate a constant energy souce or you could model them as carbon reacting with O2 in the air for a more realistic simulation.

Good luck.

 Pablo Sanchez August 25, 2006 08:41

Re: Modeling question: coal combustion

Allan,

Thank you for the feedback. As I am burning "natural hardwood charcoal" which is random in size, I can't apply your idea of resolving the individual briquettes.

Since what I am really after is the temperature distribution in the offset smoke chamber, the chemical composition of the hot gas is not important to me, and therefore I am going to save the effort of modeling the combustion process if I can accurately represent the charcoal layer with porous media.

Thanks again for the information.

Pablo

 andri August 28, 2006 01:32

Re: Modeling question: coal combustion

i have problems in biocoal combustion simulation that has many composition .must i use prePDF for simulation chemical reaction??and how to convert prePDF to fluent.and how to convert material properties in pre PDF to material properties biocoal briquette in simulation???because in bundary condition biocoal briquette is solid so its material properties is solid,but i want to change solid material propertis to Pre PDF material properties "mixture".what must i do to make simulation?

i hope help

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