what is the use of &REAC FUEL line in the FDS

[Narayan pandit]

Dear Sir/  Madam,
Currently am simulating a train compartment fire scenario which includes multiple combustibles, wherein i have defined all material properties under &MATL ID including the gaseous species produced during combustion. Also i have defined a VENT with HRRPUA=8000 as initial source of fire under the upholestery seat. I have used REAC FUEL as PROPANE, but am not able to understand where the REAC FUEL properties are used in the combustion when i have defined all fuels.( FDS6 needs to have a REAC line.) Also please let me know  how to use REAC line when multiple solid combustible are present. (am considering single reaction infinitely fast chemistry for all combustibles ex: upholestery, plywood, PVC)

[fde]

If you are planning to input single reaction, then you will have one type of REACtion.

Have you checked 8.5.4 Userguide?

HRRPUA 8000 seems high, do you use an experimental data?

[Narayan pandit]

THank You fde,
I read section 8.5.4, also i checked example pyrolysis_2, in which there was no REAC line. i wanted to know where or to which code the REAC is associated? for example MATL ID is associated with SURF ID and SURF_ID is mentioned in OBST line. I dont have any experimental data, am trying to learn FDS and all the values or properties are assumed or imaginary. if there was REAC_FUEL = '-------' code which could be linked to SURF or to a VENT, it would have been more easy to understand.

[fde]

It is not fast chemistry but there is an example on page 151 of Userguide. You can choose which SPECs take place in the mixture. Mass flux represents the amount of SPEC being injected from the SURFace.