There is a furnace in which a small porous layer exists at the bottom. Combustion is happening in the furnace and co, co2 and temperature are developed which are used for the reduction process to happen in the bottom porous layer and accordingly variation of co and co2 as well as temperature will come inside the furnace. i.e. co concentration will reduce sometime and at another instance it will increase according to the reaction kinetics. The reduction part inside the porous medium has to be incorporated as a UDF.

The reduction of iron ore coal composite pellet proceeds by the formation of the intermediate oxides evolution, which includes the following steps, i.e. hematite first gets converted to the magnetite then from there to wustite and finally iron and all these reduction happens by the regeneration of CO through carbon gasification equation. First order kinetics has been used for the reduction equation. details of rate eq is given n file attached. R=(4*phi*r^2)exp(E/RT)(CONCco-(CONCco2/T)) for iron ore reduction, where CONCco is the concentration of co etc. like wise for carbon gasification as well. i have written a udf using DEFINE_SOURCE but no variation in CO and CO2 concentration was observed. What type of model specific UDF should be used for executing reduction process such that mutual interaction between combustion and radiation will be there inside the furnace. like DEFINE_VR_RATE, DEFINE_EXCHANGE_PROPERTY, DEFINE_SOURCE............I AM TOTALLY CONFUSED.kindly help me out