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This work present a study of a solar wood dryer in a Moroccan climate. The wood drying process is investigated theoretically by a mathematical model based on actual climate data. The model constantly gives dryer humidity and temperatures (air and walls) as well as wood temperature and moisture contents. For verification, the present drying model is executed within the simulation program with experimental data of wood drying experiments conducted in two dryers located in two different sites. The computational results show a reasonable agreement between the predicted and measured wood moisture content.Key words: Solar dryer, Modelling, Wood, Temperature, Moisture content reSumen Este trabajo presenta un estudio de un secador solar de madera en un clima marroquí. El proceso de secado de madera es investigado teóricamente desarrollando un modelo matemático basado en datos climáticos reales. El modelo da a cada momento, la humedad y la temperatura del secador (aire y paredes) así como la temperatura y la humedad de la madera. Para la verificación experimental, este modelo de secado es introducido en el programa de simulación con datos experimentales de secado de madera de los experimentos realizados en dos secaderos situados en dos lugares diferentes. Los resultados muestran un acuerdo razonable entre la humedad de la madera predicha y medida experimentalmente.

This work presents verification of a mathematical model for drying of a wood stack in a greenhouse type solar dryer. A simplified heat and mass transfer numerical model has been developed with input parameters based on the actual metrological data of a Moroccan climate. For its validation, a comparative study is performed in this work; the present model is solved to simulate the solar drying of pine wood using experimental data of previous wood drying experiments. The average relative discrepancies between the model predicted and experimental data are 1,2% for wood moisture content, 1% for drying air temperature and 5% for the air relative humidity. The close agreement between the predicted and experimental results shows the ability of the model to reproduce experimental drying data for wood.

This work is part of a program that aims at studying the burr wood of thuja (Tetraclinis articulata). The goal of this work is to identify material symmetries of burr wood to improve its machining. To have a sufficient number of data and to limit the variability between samples, an ultrasonic experimental device, in direct contact on spherical samples, has been developed and improved. Until now, the geometry used in direct contact ultrasonic methods was either cubic or polyhedral allowing to obtain, on the same sample, 3 (cube) to 13 (polyhedron) measurements or usable data. By choosing a reasonable angular gap, the spherical geometry allows the ultrasonic velocity to be measured in 133 different directions on the same specimen. We present here the adaptation and development of the ultrasonic experimental device and results obtained on (i) aluminum chosen as a reference material, (ii) beech wood and (iii) burr wood of thuja.