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An X-ray density analyzer was used to determine the evolution of the moisture content (MC) profiles of a wood board during drying. Tests were performed on quartersawn boards of five wood species (oak, beech, Scotch pine, birch, alder) of two thicknesses (20 and 40 mm) dried at low temperature. The water vapor diffusion coefficient and liquid permeability of each wood species were determined by inverse analysis of the profiles using a computational model of coupled heat and mass transfer. These parameters were also measured by classical methods for validation purposes. The inverse method gives values close to the measured ones when using the evolution of the moisture profile, but also quite remarkably when using only the evolution of moisture at the core of the board. On the contrary, the method is less accurate when using only the average kinetics as experimental information. [ABSTRACT FROM AUTHOR]

Intermittent drying may be of interest in the future to address energy issues. Such drying conditions are also likely to help stress relaxation through mechanosorptive creep. The influence of applying oscillations of temperature and relative humidity during the drying of beech timber on time and drying stresses is discussed in the paper by means of nonsymmetrical and loaded drying. Experimental data were used to validate a numerical model in the case of intermittent drying. The model was then used to perform a numerical investigation of the possibility of using an intermittent energy source to dry wood. [ABSTRACT FROM PUBLISHER]

In this study, the drying of thin layers of the “Violet de Galmi” onion (a variety mainly grown in West Africa) is presented in this article, along with the reaction engineering approach (REA) modeling for a comprehensive understanding of the drying kinetics. The experiments were conducted on a lab-scale dryer to form thin layer of cylindrical onion slice. By performing this experiment, the standard activation energy is evaluated and modeled. The model is validated by simulating the drying rates under various drying conditions. The comparison of simulation and experimental data is found to be satisfactory. This approach allows the determination of the internal characteristics of the onion for the further studies such as design of solar dryer for onion. [ABSTRACT FROM PUBLISHER]