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Author Topic: Soot Yield vs Mass Fractions  (Read 585 times)

Karthik Kayaroganam

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Soot Yield vs Mass Fractions
« on: April 06, 2021, 10:24:09 pm »

Good day to everyone,

Just checking on the following. I am conducting a recirculation study (i.e. to show that the smoke exhausted from a vent does not recirculate back into the Fresh Air vents for the same system at the external). Therefore instead of modelling an actual fire (e.g. 5MW) in the compartment and modelling the smoke movement through the ducting system all the way to the external, i have instead modelled a burner surface at the external with these parameters:
a. Supply (to modelled exhausting of smoke)
b. Thermal boundary conditions - using the Boundary Condition Model for Fixed Temperature (utilizing the hot smoke layer temperature based on prescriptive calculations)
c. Species Injection - Soot Mass fraction of 0.1kg/kg

I would like to enquire if the setting of the soot mass fraction as such is equivalent to the setting of soot yield as 0.1 in the byproducts?

Aside to the above, in terms of tenability criteria, can it be said that a visibility more than 30m is considered to be equivalent to no smoke recirculation? if yes can i know if there are any codes i can use to substantiate this. If no, what would be an acceptable method or criteria to use when defining recirculation (or lack of smoke circulation)

Thank you and Regards
Karthik
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Bryan Klein

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Re: Soot Yield vs Mass Fractions
« Reply #1 on: May 21, 2021, 03:26:40 pm »

I would like to enquire if the setting of the soot mass fraction as such is equivalent to the setting of soot yield as 0.1 in the byproducts?

No, mass fraction of a supply air flow is not the same as the mass fraction of the fuel that converts to soot as a byproduct of combustion.
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