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 a 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 © 2005 John Wiley & Sons, Ltd.

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

Cryoconcentration is a natural phenomenon which occurs during the ice thawing. More concentrated phase is then separated from the initial solution. This phenomenon was exploited for scientific objectives and the results were impressive. The use of the cryoconcentration technology in the bio-food industry makes it possible to obtain products of high nutritive, biological and organoleptic value. The aim of this review was to trace a detailed synthesis of the basic principles of this concentration and extraction technique, to summarize in one document the potential and principal applications reported in the literature and to try to predict the future and the necessary conditions for the industrial success of this technology.

Cryoconcentration technology in the bio-food industry: Principles and applications

Pyrolysis of large wood particles: a study of shrinkage importance in simulations☆ ☆

Efficient ice slurry generation systems continuously produce ice crystals of desired size offering high cooling rates without any wall freeze-up. Although several ice slurry generation technologies have been and are being developed, currently only the scraped surface and supercooling type have been widely used in commercial applications. Typical ice slurry generators require the use of mechanical devices such as scraper blades, orbital rods or impacting solid particles to maintain a freeze-free ice-generating surface and achieve a continuous ice slurry production. The basic principles, operating ranges and heat transfer characteristics of the scraped surface and fluidized bed type ice slurry generators are reviewed. From this review it became clear that the basic crystallization principles and heat transfer mechanisms in current ice generators are not yet fully understood. To elucidate the heat transfer mechanisms, heat transfer measurements are presented in a prototype compact ice generator.

E.J. De Jong

Papers

Heat transfer properties of a scraped-surface heat exchanger in the turbulent flow regime

Particle-particle interactions in poly-sized solid-liquid suspensions