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Author Topic: Very low levels of CO concentration  (Read 1998 times)

Cade_Foster

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Very low levels of CO concentration
« on: December 16, 2016, 04:08:35 am »

Hello everybody,

I am carrying out a simulation of a fire in a tunnel, and one of my goals is to assess the levels of CO concentration.

The fire definition is the one contained in the attached images.

- Reaction of polyurethane
- Same reaction as default, but reducing the soot yield to 0,1.
- Fire of 15MW, in the external top surface of a train car (20 m2).

The tunnel has the following features:

- Cross - sectional area: 50 m2.
- Height: 7,5m
- Ventilation around 1-2,5 m/s.

As you will see in the pictures that I attach to this email, the levels obtained for CO concentration are always below 700 ppm and they are placed only in the upper part of the tunnel.

These values seem too low to me. Have i made any mistake?

Thank you for your support.

Best regards.
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Bryan Klein

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Re: Very low levels of CO concentration
« Reply #1 on: January 02, 2017, 05:40:00 pm »

Hello,

What concentration do you expect to see?  On what basis do you expect to see that value?
It looks like 4.2% of your fuel mass release should be CO, do you see this amount in the Mass data output file?

One of the first things to do when running a calculation is knowing what your expectations are, and how you can justify them.

Please see the attached screenshot to see where to enable Mass data output, in the Output tab of the Simulation Parameters dialog.  You can then compare the CO mass released over time with the fuel mass released over time and verify that it is close to your target CO yield value.
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