Confusion about biomass pyrolysis in MFIX-21.4

MFiX
#1

Hello researechers, I am using the variable density model to study the pyrolysis process of biomass. The chemical reactions occurred during pyrolysis are as follows.

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As shown in the third reaction, biomass pyrolysis produces char, but the volume fraction and density of char is always zero during simulation. I’m very confused about this.
variable_density.zip (35.2 MB)

#2

Since you have zero initial phase 3 content, and you probably generate a very small amount, my guess is it stays below the threshold zero_x_gs and zero_ep_s. You can decrease these tolerances and maybe include a tiny fraction of phase 3 in the bed just to be sure phase 3 is tracked. You may have to play with these tolerances as it may be a bit unstable.