Which model is suit for this type of combustion
 

Hi I want to simulate this combustion problem,which coal layer is fixed and the primary air was injected through the bottom of the coal layer,the secondary air was injected up the top of coal layer. I want to know how do the all kinds of smoke specials vary with the time. The question is which model is suit for this case? Can the "seven gas model" deal with the unsteady problem? Anyone like to have a friend to disuss the subject on coal combustion is welcome. thanks.