Fire load in CFAST

[ce17...@smail.iitm.ac.in]

Hi All,

Which factor in CFAST model takes care of fire load or fire load density in case of a ventilation controlled fire? 

Could anyone someone help me understanding this?

Thank you.

[Andy Tam]

It can be the lower oxygen limit and if the oxygen of the layer is below the lower oxygen limit, the HRR of fire will be reduced.

Thanks,

Andy

[Richard Peacock]

The basic premise in CFAST is that the user defines the heat release rate of fire.  Beyond that, CFAST does keep track of the oxygen available for combustion in the plumes and layers in each compartment. If there is sufficient oxygen for combustion (defined by the total mass of oxygen required for combustion and the lower oxygen limit), the user-defined heat release rate is used.  If there is not sufficient oxygen, CFAST will reduce the heat release rate to match the available oxygen.  

The lower oxygen limit, a global, user-adjustable parameter in the model, defines the amount of oxygen available.  If the oxygen concentration goes below this limit, further combustion will not take place at that location.  Any unburned fuel is transported either to the upper layer of a compartment (in the case of lower layer burning) or through vents (in the case of upper-layer burning) where further combustion may take place with oxygen as available in the upper layer or door jet plume.

I hope this helps.

Richard Peacock

On Saturday, December 29, 2018 at 3:18:30 AM UTC:

[Namita Nayak namitanayak519]

Thank you Mr. Rechard.

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