Impact of Initial Moisture Content on the Drying Process of Wood Exposed to Infrared Radiation

Abstract

This article reports the results of temperature measurements carried out on 50-mm-thick Norway spruce (Picea abies [L.] Karst) wood samples exposed to infrared (IR) radiation. The varied property with respect to the optimization of the drying technology was the initial moisture content of samples. During the experiments, temperature profiles were registered on the surface and in the core of the samples under controlled technological conditions. Based on our osmotic approach, the variability in the curves was interpreted with respect to the stagnation temperature below the fiber saturation point (FSP). We conclude that the amount of liquid water necessary for osmosis must still be available locally in the core. With decreasing initial average moisture content, the time interval of the osmotic process also decreases. In this context our results support the hypothesis that the presence of free water in the wood tissue is necessary for the osmotic mechanism even if the average moisture content falls below the FSP.

Research on optimizing the drying process of Pyinkado (Xylia Xylocarpa) by vacuum infrared radiation drying method

“…The vacuum drying also led to a high temperature, the high-pressure difference between the center and the surface of the product and incremented the drying rate; this will enhance the mass transfer, hence increasing the wood's defect ratio. Similar results were reported by the other researchers using a vacuum dryer and various experiments for drying pine [3], Norway spruce [7], jujube powder [11] and almond kernels [12]. 3) to find the value, the results are shown in Table 7.…”

“…Besides, the vacuum infrared drying methods, infrared (IR) irradiation is also used by Kollmann et al [5] or set up complex drying processes Altun et al [6]. In earlier work Caserta et al [7] the mechanism of wood drying by infrared radiation was studied. The results showed that the moisture migration mechanism could be considered a semipermeable process with the moisture being a dilute aqueous solution.…”