CO yield in a combustion

[foster...@gmail.com]

Hello everybody,

I am studying the development of a 15 MW fire in a compartment. The main component that is burning is polyurethane foam.

I have seen in the SFPE handbook that, for well ventilated fires, the CO yield is 0,042. Besides, the maximum theoretical value of CO yield is 1,41.

My case is a train car (20m long, 3m high and 3m wide), with two doors of 3m2 of surface each one.

I don't know exactly how to choose the CO yield for this case, but al least I know that it has to be a value between 0,042 and 1,41. 

Should I carry out previous simulations in order to know the mass of aire entering the car and try to extract some conclusions?

Which is your opinion? 

Thank you for your aid, cheers.

[Dave Sheppard]

I would first determine whether the fire would have enough available oxygen by running a simple preliminary model with a 15MW fire with two 3m2 doors. I suspect that the fire would quickly become oxygen limited. This preliminary calculation would help you to determine the type of gas yield data that you should be looking for.

[Randy McDermott]

To add to what Dave said, if you are confident in the HRR curve, the example 2-step mechanism used in

https://github.com/firemodels/fds/tree/master/Validation/NIST_FSE_2008

has shown very reasonable accuracy to CO prediction in both ventilated and under-ventilated full-scale compartments.  There are validation metrics in the guide to check this.

On Sat, Jan 21, 2017 at 8:24 AM, Dave Sheppard <drdtsh...@gmail.com> wrote:

I would first determine whether the fire would have enough available oxygen by running a simple preliminary model with a 15MW fire with two 3m2 doors.  I suspect that the fire would quickly become oxygen limited.  This preliminary calculation would help you to determine the type of gas yield data that you should be looking for.

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[foster...@gmail.com]

Thank you very much to both of you.

I will check it out.

Cheers.

El sábado, 21 de enero de 2017, 14:28:41 (UTC+1), Randy McDermott escribió:

To add to what Dave said, if you are confident in the HRR curve, the example 2-step mechanism used in

https://github.com/firemodels/fds/tree/master/Validation/NIST_FSE_2008

has shown very reasonable accuracy to CO prediction in both ventilated and under-ventilated full-scale compartments.  There are validation metrics in the guide to check this.

On Sat, Jan 21, 2017 at 8:24 AM, Dave Sheppard <drdtsh...@gmail.com> wrote:

I would first determine whether the fire would have enough available oxygen by running a simple preliminary model with a 15MW fire with two 3m2 doors.  I suspect that the fire would quickly become oxygen limited.  This preliminary calculation would help you to determine the type of gas yield data that you should be looking for.

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[foster...@gmail.com]

Excuse me,

I don't usually enter this platform, I usually prefer to examine online pdf documents from the NIST. 

Which is the example 2 mechanism that you mention in your message?

Thank you.

El sábado, 21 de enero de 2017, 14:28:41 (UTC+1), Randy McDermott escribió:

To add to what Dave said, if you are confident in the HRR curve, the example 2-step mechanism used in

https://github.com/firemodels/fds/tree/master/Validation/NIST_FSE_2008

has shown very reasonable accuracy to CO prediction in both ventilated and under-ventilated full-scale compartments.  There are validation metrics in the guide to check this.

On Sat, Jan 21, 2017 at 8:24 AM, Dave Sheppard <drdtsh...@gmail.com> wrote:

I would first determine whether the fire would have enough available oxygen by running a simple preliminary model with a 15MW fire with two 3m2 doors.  I suspect that the fire would quickly become oxygen limited.  This preliminary calculation would help you to determine the type of gas yield data that you should be looking for.

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[Randy McDermott]

Look at the input file examples in FDS_Input_Files

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