Heat transfer mechanisms and multi-step kinetics in the ablative pyrolysis of cellulose

A new model is presented of a cellulosic cylinder which thermally degrades, because of a high pressure contact of its bottom side against a hot spinning disk. From the chemical point of view, the solid undergoes, in the first place, a depolymerization process with the formation of a molten active intermediate which. subsequently, vaporizes or gives rise to the formation of chars and gases. From the physical point of view, the model accounts for transport phenomena through the porous solid and the molten layer (adjacent to the hot plate) whose properties and size vary during thermal degradation. The dependence of process dynamics, ablation rate, thickness of the reaction zone and product yields on the plate temperature and applied pressure are simulated. Some important experimental findings are confirmed.