[audrey]

Hi everyone,

I'm a beginner at CFD, and I'm trying to decide on the best approach to solve my solid-gas flow problem.

I am modelling the pyrolysis of biomass (wood pellets) inside a rotary kiln. I'm particularly interested in what happens to the solid particles, because the desired product here is char.

Basic description of my system: I have a long horizontal cylinder (inclined at about 1 degree from the horizontal) which is rotating about its centerline. The kiln is half-filled with wood pellets and nitrogen purges the system. External heat causes gases to be released from the biomass and char is formed.

I'm wondering whether a Euler-Euler or Euler-Lagrange approach would be most appropriate for my problem. I am interested in the temperature and gas environment of individual particles, but a standard Lagrangian approach won't cut it because the volume fraction of solids is high (1 or almost 1) in a large part of the system. I've read about the dense discrete phase model implemented in Fluent 12, but its documentation is lacking a bit and the user guide suggests that it's still patchy. Does anybody know if something similar exists in CFX?

I’ve been working with CFX 12 until now, but the user manual mentions that multiphase reactions are not available for Euler-Euler problems.

I’d be happy to hear people’s opinion about the best approach for this problem (and best software between CFX and Fluent if you feel there is a significant difference).

Thanks,
Audrey