My name is Sergio González S., and I am working on a simplified simulation of a circulating fluidized bed reactor (CFBR) using MFIX 2024 software. My objective is to model a rectangular CFBR where air and solid particles enter through the bottom inlet, rise through the reactor, and are recirculated back to the inlet after exiting through the top outlet. This configuration aims to replicate the particle recirculation and gas flow characteristic of circulating fluidized bed reactors, though in a simplified design.
I have attempted to implement this recirculation loop in MFIX but am encountering some challenges. Below are specific areas where I would appreciate your guidance:
Boundary Condition Configuration for Recirculation Loop: Is it possible in MFIX to define a boundary condition where the top outlet is directly linked to the bottom inlet to simulate flow recirculation? I would like to know if MFIX supports this configuration or if there are recommended methods for achieving this type of recirculation.
Implementation of Flow and Solids Recirculation: I am exploring how to capture the flow properties at the top outlet (air velocity, particle loading) and apply them to the bottom inlet at each time step. I would appreciate any recommended methodologies or documentation that describes how to implement this logic in MFIX.
Any guidance, additional documentation, or configuration examples that could help me implement this recirculation simulation in MFIX would be greatly appreciated.
This is not natively supported, but this may be achieved with custom code (user-defined-functions, or udfs).
One possible strategy would be to start with monitors, to capture the outlet flow properties. Then you would use this information to reset the MFiX keywords that control the mass inlet BC. I have not tried that. Will be tricky if you have backflow.
I am using MFIX version 24.3 and trying to modify parameters or customize what seems to be the core code within the MFIX environment. I’ve attached a screenshot showing the fluid_bed_tfm_2d.mfx file, which I can view in the project explorer, but I’m not sure how to proceed to edit it or if it is possible to directly modify the code governing the simulations.
Could anyone guide me on how to make these modifications? For example:
Is this the appropriate file to adjust advanced parameters or customize the model?
Is it necessary to use an external text editor outside of MFIX?
What precautions should I take to avoid affecting the integrity of the project?
I would greatly appreciate any help or suggestions!
The fluid_bed_tfm_2d.mfx file is created by the GUI, and you typically do not need to edit this file. It is shown in the editor for advanced users that may be interested in seeing the keyword values.
In theory, you can edit the file outside the GUI (while the file is not already in use by the GUI), but you take the risk of corrupting the file. We recommend to not edit the file unless there is a very specific need for it (say a keyword must be manually changed due to a bug in the GUI and this workaround is necessary while the bug is being fixed).
I recently asked about modifying the fluid_bed_tfm_2d.mfx file because I am trying to simulate a simplified circulating fluidized bed reactor (CFBR). My goal is to focus exclusively on modeling the reactor’s main section, where I aim to create a loop or recirculation mechanism. Specifically, I want solid particles exiting through the reactor’s top outlet to be reintroduced into the bottom inlet to simulate the particle recirculation characteristic of CFBRs. (Refer to Image 1 for a conceptual illustration.)
This idea stems from my challenges in building a CFBR in MFIX. I attempted a 3D simulation of a CFBR (as shown in Image 2) but encountered difficulties, particularly with configuring the bed correctly in the reactor’s riser section. I’m unsure how to set up the fluidized bed properly within the riser and configure the required parameters for the recirculation and elevation processes.
I would greatly appreciate any advice, documentation, or example setups that could help me move forward with this project.
