Just a clarification: The reaction rate unit for for DEM/PIC (usr_rates_des.f) is
mol/s in CGS
kmol/s in SI
It is strongly recommended to always use MFiX SI units. The GUI only supports SI units. It will convert old mfix.dat that were written in CGS units, but it cannot convert udfs and it is the user’s responsibility to make sure udfs use the correct unit system.