Palm wood drying and optimization of the processing parameters

Abstract

Drying is an essential operation in transforming wood into a finished product in order to ensure good stability during use. During the drying process, wood undergoes strong warping, which can spoil the quality of the finished product, producing internal slits, tensions, distortion, etc. The hygrothermal characterization of the product during and after drying is necessary to avoid these defects. The aim of this work was to determine some hydrothermal characteristics of palm wood in order to propose a drying schedule for this product. The drying kinetics of palm-wood boards (dimensions 2×5×30 cm) were determined under forced convection at low temperatures. Operating parameters of air temperature, relative humidity and air velocity were allowed in the ranges 40–70°C, 30−80% and 2–3.5 m s⁻¹, respectively. Desorption isotherms were measured at temperatures of 50, 60 and 70°C using a static gravimetric method and the predictive correlation of these isotherms was also established. The net heat of desorption was evaluated by explaining the Clausius–Clapeyron equation. A quality criterion at which damage was expected was obtained through static bending tests carried out on the wood boards.

Keywords:

• Convective drying kinetics
• desorption isotherms
• drying schedule
• isosteric heat
• palm wood
• static bending stress

Acknowledgements

We thank Mr Slim Ben Gamra, technical director, and Mr Najib Albouchi, principal engineer at the Centre Technique de l'Industrie de Bois et del'Ameublement “CETIBA”, for his help in carrying out mechanical tests. Our thanks go to Mr Ayoub Ben Ali president of Association “Appuis aux Initiatives de Développement” and Mr Samir Droue for their support and helpfulness during samples proxy.