WOOD RESEARCH Volume 68, Number 2, 2023
CHUNMEI YANG, ZANBIN ZHU, Jiuqing Liu, BO XUE, and YUCHENG LI

Model construction and microwave preheating experiments using fiberboard

Microwave heating is a new type of pre-heating for fiberboard mats. Compared to conventional heating, microwave heating is faster and the surface and interior are evenly heated, thus avoiding the phenomenon of premature hardening of the surface layer of the fibreboard mats. In this paper, the heat transfer law of microwave preheated fiberboard mats was analyzed, and a thermodynamic model of fiberboard microwave heating was established. Furthermore, a microwave preheating simulation was established through COMSOL software; the temperature distribution of the fiberboard after microwave heating was analyzed and the reliability of the simulation model was verified through experiments. The temperature changes of fibers in the two preheating methods were compared by direct contact preheating experiment and microwave preheating experiment. Microwave preheating is more efficient than direct contact preheating, and more uniform temperature distribution in fiberboard mats. The core layer temperature is higher than the surface layer temperature, which can shorten the preheating time. By comparing the COMSOL model with the test, the model can basically reflect the temperature change law of microwave preheating, and the temperature of each layer of the slab is more uniform in the model simulation process. The heating law of the fiberboard was obtained, which provided a theoretical reference for the industrialized microwave preheating of fiberboard.

WOOD RESEARCH Volume 64, Number 1, 2019
Burak Turkan and Akin Burak Etemoglu

Numerical investigation of wood drying

In this study, forced convective drying process of wood material with rectangular shape was investigated. Firstly, governing equations for the flow field were solved by using ANSYS Fluent. Then average heat transfer coefficient on the surface was calculated by using Standard k-ɛ Turbulence Model. It was found that mass transfer coefficient making use of the relationship between heat and mass transfer. Simultaneous heat and mass transfer equations were solved transiently with Comsol Multiphysics using surface boundary conditions for selected air velocity, air temperature and material thickness. In drying process the moisture and temperature distributions inside the solid were obtained transiently. The mathematical model for equations was formed using Fourier heat and Fick diffusion models. Results acquired from the present model were compared with a study results which are available in literature and it was shown a very good agreement.