[Tulo]

Hi All,

I am working on a coal combustion modelling problem.

For the two competing devolatisation reactions, I would want to specify the VM product composition for Low-Temp Devolatilisation as 32.8 % CO, 61.0 % C2H4 and 6.2 % H2, and for the High-Temp Devolatilisation as 22.6 % CO, 72.7 % C2H6 and 4.7 % H2.

I guess I've to develop a UDF for this and if anyone has done this before, will be grateful if you could advise on this.

Cheers!

[alainislas]

I guess you are working with DPM model?
By default, Fluent's devolatilization product is only 1 product. This is a pseudo-molecule that is further oxidized to represent the combustion of the "volatile or volatiles" gases.

A turn-around to your problem might be something like:

(1) define a relatively low devolatilization temperature for the pseudo-molecule. Use a single kinetic rate devolatilization model and set very fast kinetics. This will move the volatile from the solid to the gas-phase almost immediately.

(2) Once that the volatile is in the gas-phase, define your two reactions, maybe

• (R1) volatiles -> x1*[CO] + x2*[C2H4] + x3*[H2] with set 1 of Arrhenius constants
• (R2) volatiles -> y1*[CO] + y2*[C2H4] + y3*[H2] with set 2 of Arrhenius constants

These reactions will crack the volatile into your 3 species, at different rates and compositions.