Mathematical model of steam drying of wood chips and other hygroscopic porous media

Journal Article · Sun Sep 01 04:00:00 EDT 1996 · AIChE Journal

DOI:https://doi.org/10.1002/aic.690420909· OSTI ID:378000

Fyhr, C; Rasmuson, A ^[1]

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1. Chalmers Univ. of Technology, Gothenburg (Sweden). Dept. of Chemical Engineering Design

A model is presented that is focused on the drying kinetics of single wood chips as a function of time and external conditions, such as temperature, pressure and velocity of the superheated steam. A multiphase and 2-D approach was used to model the coupled transport of water, vapor, air and heat in anisotropic hygroscopic porous media. The model was verified by drying experiments where measurements of the average moisture content, center temperature and pressure in a single wood chip could be performed simultaneously. A comparison between the calculations and the measurements showed that the drying behavior was well predicted. The drying can be divided into three stages: a heat-up period when condensation on the surface initially increases the moisture content; a period of constant drying rate when the external heat transfer controls the drying rate; and a period of decreasing drying rate when the drying is controlled by internal mass transfer. Many interesting features of the drying could be assigned to the strong anisotropicity of wood, which makes a 2-D model necessary.

• OSTI ID: 378000
• Journal Information: AIChE Journal, Journal Name: AIChE Journal Journal Issue: 9 Vol. 42; ISSN 0001-1541; ISSN AICEAC
• Country of Publication: United States
• Language: English

Related Subjects

09 BIOMASS FUELS
AIR QUALITY
DRYING
ENVIRONMENTAL IMPACTS
HEAT TRANSFER
MASS TRANSFER
MATHEMATICAL MODELS
PARAMETRIC ANALYSIS
POROUS MATERIALS
SOLID FUELS
TWO-DIMENSIONAL CALCULATIONS
WATER VAPOR
WOOD WASTES