The state-of-the-art in pyrolysis modelling of lignocellulosic solid fuels

Recent advances in mathematical modelling and numerical analysis of the pyrolysis of char forming solid fuels have shed new light on the pyrolytic behaviour of these materials under fire conditions. A review of the pyrolysis models of lignocellulosic (wood-based) charring solid fuels developed over the past 60 years is presented in order of increasing complexity. The review, however, is limited to pyrolysis models developed for high temperature and high heating rate conditions and does not encompass the pyrolysis of wood-based materials under conditions pertinent to 'steam pipe' type problems encountered typically at low temperatures, low heating rates and relatively long residence times. The models can be broadly categorized into thermal and comprehensive type models. While thermal models predict the conversion of the virgin fuel into products based on it critical pyrolysis criterion and the energy balance, the comprehensive models describe the degradation of the fuel by a chemical kinetic scheme coupled with the conservation equations for the transport of heat and/or mass. A variety of kinetic schemes have been reported in the literature ranging from simple one-step global reactions to semi-global and multi-step reaction mechanisms. There has been Much less uniformity in the description of the transport phenomena (i.e. heat and mass) in comprehensive models and different levels of approximation have been used. It is shown that the accuracy of pyrolysis models largely depends on the model parameters. Copyright (c) 2005 John Wiley & Sons, Ltd.