Heat of combustion for FDS simulation

[kxglp]

Dear all,

 

I would like to seek your advice for a FDS case.

 

Currently, I am simulating a fire in a room, the original HEAT OF COMBUSTION is around 2.1E4 KJ/KG, and I can get the target ramp-up of HRR. However, when I change the HEAT OF COMBUSTION to 6E3 KJ/KG, the HRR is negative and the combustion does not happen.

 

This is a simple case, but I am interested to learn the mechanism behind this. I look through FDS manual, but I cannot find the limitation of HEAT OF COMBUSTION on the occurrence of combustion. Would you please advise on this?

 

The  FDS case is attached for your reference.

 

kxglp

[dr_jfloyd]

The FDS extinction model will not allow combustion to take place if a critical flame temperature cannot be reached, your fuel chemistry does not allow this to happen if the heat of combustion is 6000 kJ/kg.  If you were to set SUPPRESSION=.FALSE. on &MISC  then you should see the desired heat release rate.

[kxglp]

Thank you.

I think this is answer. By adding the MISC line, the model works.