A Three-dimensional Mathematical Model For The Pyrolysis Of Wet Wood

Abstract

A three-dimensional mathematical model for the pyrolysis of wet wood including a detailed consideration of the evaporation of moisture, anisotropic and variable properties, and pressure driven internal convection of gases in wood has been developed. A computational code has been formulated modelling multiple competing reactions for up to six constituents, although a single firstorder Arrhenius reaction is adopted in the results presented. The pyrolysis of a beech wood cube with different initial moisture contents has been computed for a range of furnace temperatures. The Arrhenius kinetic parameters have been determined by a method of best fit to the experimental results of Bonnefoy et a1 [16]. The values agree very well with the range of kinetic data reported by Tinney [4]. The computed results giving a full 3-D description of the transient chemical and physical processes of the pyrolysis of a wet wooden cube heated in a furnace are presented. The influences of the anisotropic properties due to the grain structure on heat and mass transfers in pyrolysing wood are discussed.

Numerical Study of the Pyrolysis of Wood Chips for Biocharcoal Production: Influence of Chips Geometry and Initial Moisture Content

“…The thermo-physical parameters used in our model might also influence the variation obtained. The presence of moisture content in the samples decreases the kinetics of thermal degradation, as shown by the experimental data used [38] and confirmed in previous works [31]. It took about 100 s to complete the pyrolysis of 30 mm parallelepiped wood at 973.15 K, and about 60 s for 1273.15 K. Comparatively, this time is similar to the pyrolysis of 20 mm spherical wood chip in the same temperature range, but lower than the time taken for pyrolysis of 20 mm height and 20 mm diameter cube and cylindrical wood chips, respectively [16,19].…”

“…To consider the presence of water in wood, the equilibrium moisture content, X eq , is calculated according to the relation of Simpson and TenWolde [31]:…”

Predicting the piloted ignition of wood in the cone calorimeter using an integral model — effect of species, grain orientation and heat flux

“…Chen et al [14]; Wichman & Atreya [15]; Yuen et al [16] and Parker [17]. These models range from simple treatments of the ignition and burning process using pure heat conduction models to the use of complex chemical kinetics for the pyrolysis of a charring material.…”

Experimental Study on Spontaneous Ignition of Wood Exposed to Variable Heat Flux

“…Atreya et al [2][3][4] have conducted extensive work on the same topic. Several models [5][6][7][8][9][10] that deal with the ignition behavior of wood have been developed. These models included most of the chemical kinetics and physical processes involved in the burning process of wood, such as drying, charring layer reaction, gas-phase reaction, etc.…”