Qustion about methanol_evaporation.fds case

[lihy213]

Hi team,
In the methanol_evaporation.fds case, why is it said to be an oxygen-depleted environment(see FDS 6.9.1 User's Guide Page 105)? I want to pyrolyze the methanol to evaporate and burn it, is it possible to specify the ambient oxygen concentration on the MISC line or not set the VENT boundary condition to OPEN.

[drjfloyd]

The User's Guide description is not completely correct for the current input file. No changes have been made to the default oxygen concentration in the default background species (what both of these are and how to change them is discussed in the Guide). It should say something like:

In this example since no gas phase combustion reaction is defined, no burning occurs.

[lihy213]

I defined `&REAC FUEL='METHANOL'/ and then burned it, does that show that methanol can burn after pyrolysis?

[drjfloyd]

It isn't clear exactly what you are asking. Can you rephrase or expand upon your question?

[lihy213]

You said that there's no gas phase combustion reaction was defined, so I defined &REAC FUEL='METHANOL. Then there's burning occurs. In this case, is it can be said that the pyrolysis model triggers methanol to burn?

[drjfloyd]

The pyrolysis model (in your case an evaporation model) is a defining a mass flux boundary condition for the solid surface (the mass flux of methanol vapor). The pyrolysis model doens't tell FDS anything about what should happen to the gas once it is in the domain. That is what the REAC input does. If there is no REAC, there will be no combustion.