Coal Combustion DPM Mechanism Problem
 

Dear Friends:

This is Brandon Han. I'm faced with a problem and I really hope someone can help me.

I am working on the numerical simulation of coal combustion using DPM. In the default Fluent approach, char combustion occurs when there's no volatile matter in the particle. In other words, if there is volatile matter in the particle, char will not react with oxygen. But I want to combine devoatilization and char combustion together. As long as the temperature is higher than devoatilization temperature, devoatilization and char combustion will occur simultaneously.

I want to use UDF to solve it. Should I use DPM_LAW to create new laws? Or should I use DPM_SWITCH to make it happen.

I will really appreciate it if someone can give me some advice.

Thank you very much.

Basically you have to code the whole think. DPM_LAW(s) + DPM_SWITCH. This is not a simple thing. When you write the DPM_LAW you have to also concentrate on the stuff which is not part of your problem solely. Like size development and so on.

Hi Habo, thanks for your reply.

In your opinion, I must create DPM_LAW first,including devolatilization and combustion. Then I should create DPM_SWITCH to switch different laws.Is that right? If that's right, then this is hard work. I don't have much experience in this and I'm pretty sure I cannot work this out.LOL.

Is there any chance I do it in different ways? Do not hesitate to provide another method that may be available.

Thanks in advance.

No, in my opinion there is no other way. This is a difficult path. Fluent has a linear structure to solve each process and there is no real way around it with default settings.



For research this is may be of interest. Maybe for fixed or fluidized beds. In entrained flow I think this is not important to consider.


Furthermore you have to implement a better/easier conversion model. But imagine you also have to code the whole diffusion process stuff.



There are many groups which have already implemented UDF structure for char conversion which can be extended to your problem -- in my opinion maybe in one month+.

Hi Habo. Thanks for your reply.

I think you are right. I'm working on fixed bed coal combustion. Maybe an appropriate method is to couple other conversion model or particle model. This is not involved in our present work. But this may be an interesting direction in the future.

However, I think I may start trying create DPM_LAW or DPM_SWITCH to solve current problems. We want to make devolatilization and char combustion occur simultaneously. I hope to get some advice but it seems there 's no good solution.

Thank you very much for this helpful discussion.