Experimental study on the drying kinetics of wood veneer in contact drying
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Insinööritieteiden korkeakoulu |
Master's thesis
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Date
2020-10-19
Department
Major/Subject
Mcode
Degree programme
Master's Programme in Energy Technology (EEN)
Language
en
Pages
47
Series
Abstract
Concerning environmental protection, we should reduce as much as possible the use of non-renewable resources and consume efficiently the renewable resources that we have. Plywood, as an engineered product, offers great opportunities to perform efficiently veneer based products from wood, which is one of the most important renewable sources. In the plywood process, the drying consumes a lot of energy. Therefore, any improvements in drying-process efficiency result in significant overall energy savings. Contact drying is an alternative technology to convective drying that is the most used in this sector due to its large industrial capacity. However, contact drying usually has better energy efficiency because the heat is directly transferred into material by conduction. This master's thesis focuses on the experimental study of a contact dryer, which is equipped with a vacuum pump to work under atmospheric pressure. Although the thesis work is divided into three blocks: the so-called drying curves, energy consumption and modelling of drying time, the main goal is experimentally defining drying times of veneers with various thickness at different work conditions. The result of these measurements are drying curves, but drying time is the wanted parameter. The most relevant factors that affect drying are the temperature of the heated plate, the pressure inside the drying box and veneer thickness. The effect of these factors is studied by measuring the drying curves that show the moisture-content behaviour in relation to drying time, helping us to understand how they influence drying process. A drying-time model is proposed to describe the veneer drying using the laboratory contact dryer. The modelling is the product of a thermodynamic analysis between the dryer and the veneer. Modelled and experimental time are compared, and the variations between them are analysed. In addition, an experimental study of energy consumption is exposed, which is useful to understand better the dryer behaviour when it is taking water out of veneers. This point in combination with the analysis of drying curves let known the fundamental aspects of contact drying for wood veneers.Description
Supervisor
Syri, SannaThesis advisor
Laukkanen, TimoKeywords
drying time, moisture content, modelled time, energy consumption