Product distribution from the pyrolysis modeling of tobacco particles

摘要

A mathematical model of tobacco pyrolysis accounting for the transport and chemical processes is presented. Pyrolysis products are formed via a kinetic scheme based on the functional groups (FG) and prescribed with a single-step multi-reaction model. Transport processes include heat transfer (conduction, convection, and radiation), mass transfer (diffusion and convection), pressure and velocity within a tobacco shred. The pressure and velocity variations within a tobacco shred are described according to the Darcy's law. The variation of physical properties such as porosity, conductivity, permeability, and mass diffusivity of a shred is monitored with the extend of pyrolysis. The finite difference formulation of the mathematical model is based on the hybrid scheme and a two-step splitting procedure is used for the treatment of chemical processes and transport phenomena. Time and space evolution of the main variables, and the pyrolysis product distribution, are simulated for both smoldering and puffing conditions. The simulation results show a reasonable agreement with the available experimental data of the yields of selected species for smoldering and puffing.