[Puru1995]

I am running combustion simulation in a domain using rice husk as a fuel. I tried using both nonpremix and species transport model. But in both cases the fuel seems to be burning in the inlet path only without entering the main furnace domain. The mass fraction of all components that is supposed to be in the domain demonstrating the reaction isnt there. The whole domain either shows nil concentration of compounds such as CO2 and water either the concentration is same throughout the vessel. The only variation can be seen in the small duct from where the fuel enters and that is where the reaction ends. What may be the possible causes of that?

[alainislas]

What is your turbulence/chemistry interaction model? Please post a screenshot of your species transport panel

[Puru1995]

https://drive.google.com/drive/folde...-c?usp=sharing

The turbulence model i am using is k-epsilon standard model. Please provide me the feedback. Thank you for your time.

[alainislas]

Please next time, attache the images directly here in the forum.

I see your TCI is EDM, this is a mixing limited TCI model, where reaction rates are assumed as inifinitely fast but controlled by turbulent mixing only. In order to avoid flame ignition befoer a flame holder (or at an inlet for example), please use the EDM/FR model. FR acts a kinetic switch, preventing reactions to take place in zones where the FR RR < EDM RR. Please go through the theory manual https://www.afs.enea.it/project/nept...th/node129.htm

[Puru1995]

Thank you for the feedback

[Puru1995]

Please provide me a suggestion on this.
Using finite rate model improved the simulation result and the combustion seems to happen in the main cylinder.
How to make sure that the combustion is complete since there is no option to view carbon monoxide concentration in the results. The concentration of fuel is nil while carbon dioxide is very low as well.

[alainislas]

What do you mean by combustion is complete? To provide suggestions, I need to know more about your case.

1. Is this a transient simulation?
2. How are you injecting the fuel?
3. What is your equivalence ratio?
4. How are you igniting the mixture?
5. Did you add the CO to your mixture? Show your species panel
6. You can track O2 mass fraction at the outlet and check whether its consumed or not.

Please elaborate

[Puru1995]

What do you mean by combustion is complete?
> I mean that the concentration of carbon dioxide is very low in the order of 10^-11.



1. Is this a transient simulation?
>No
2. How are you injecting the fuel?
>The air enters tangentially through a rectangular inlet and the fuel drops on the air stream from the top in perpendicular direction such that the air carries it.
3. What is your equivalence ratio?
>Around 0.9
4. How are you igniting the mixture?
>I have one of the walls that holds the nozzle maintained at 500K.
5. Did you add the CO to your mixture? Show your species panel
>No. I used the coal calculator and the reactants and products are as shown in the image earlier.
6. You can track O2 mass fraction at the outlet and check whether its consumed or not.
>The oxygen is at same concentration throughout the domain.

[alainislas]

Again, please re-attach your images directly here in the thread and do not use external links. This facilitates many users and I to jump into the conversation, avoid going to untrusted sites, and provide better assistance.



1. From what I saw (I will not open again the link), you only had 1 volumetric reaction, but before that. Are you really devoatilizing the 'vol' species in the particle? Please take a look at some contours.

2. Are you really injecting the DPM? What is your DPM mass flow rate? Take some screenshots of the DPM trajectories and add them here.

3. 500 K for ignition is too low, what is your devolatilization temperature? Besides that, do you have any other DPM law enabled? If you have moisture in the DPM, what about the evaporation? This will of course consume enthalpy and decrease your temperature.

4. The coal calculator has a template that directly adds the participant species in the volumetric reaction into the mixture. Did you add any solid species too?

4. Any judgment should be done after reaching a steady-state condition-

[Puru1995]

From what I saw (I will not open again the link), you only had 1 volumetric reaction, but before that. Are you really devolatilizing the 'vol' species in the particle? Please take a look at some contours.
I am including some of the contours. They are not as better as they were before changing the injection settings
co2.PNG

injection.PNG

no volatile.PNG

reaction.PNG

2. Are you really injecting the DPM? What is your DPM mass flow rate? Take some screenshots of the DPM trajectories and add them here.
it seems like i hadnt customized the injection settings. I have included the latest settings here

3. 500 K for ignition is too low, what is your devolatilization temperature? Besides that, do you have any other DPM law enabled? If you have moisture in the DPM, what about the evaporation? This will of course consume enthalpy and decrease your temperature.
i increased the temperature to 1000K

4. The coal calculator has a template that directly adds the participant species in the volumetric reaction into the mixture. Did you add any solid species too?
I dont think so

4. Any judgment should be done after reaching a steady-state condition-

[Puru1995]

From what I saw (I will not open again the link), you only had 1 volumetric reaction, but before that. Are you really devolatilizing the 'vol' species in the particle? Please take a look at some contours.
I am including some of the contours. They are not as better as they were before changing the injection settings
Attachment 93703

Attachment 93706

Attachment 93707

Attachment 93708

sideon view co2.PNG
2. Are you really injecting the DPM? What is your DPM mass flow rate? Take some screenshots of the DPM trajectories and add them here.
it seems like i hadnt customized the injection settings. I have included the latest settings here

3. 500 K for ignition is too low, what is your devolatilization temperature? Besides that, do you have any other DPM law enabled? If you have moisture in the DPM, what about the evaporation? This will of course consume enthalpy and decrease your temperature.
i increased the temperature to 1000K

4. The coal calculator has a template that directly adds the participant species in the volumetric reaction into the mixture. Did you add any solid species too?
I dont think so

4. Any judgment should be done after reaching a steady-state condition-

[Puru1995]

why am i not able to change the droplet particledp.PNG

the injection
inj dir.PNG