Drying of Thick Foam Formed Mats Comprising Chemithermomechanical Pulp Fibers

This paper focuses on the drying studies of foam-formed wood fibre based relatively thick materials via infrared drying, impingement drying, and microwave drying. The drying experiments were carried out for materials with three initial moisture ratios and thickness levels. Material selection was guided by the possibility of using these kinds of materials in packaging and construction applications. The motivation for this study was the fact that in water-based manufacturing a lot of energy is consumed during the drying phase; therefore, the better understanding of drying kinetics is essential for improving the environmental friendliness and cost efficiency of material production. The results revealed differences in the results of drying methods and limitations for thick, porous wood fibre-based materials. The differences in these methods affected the drying rates and material quality, which both can arise as the limiting factor for material production. The highest drying rate was observed using microwave drying, the intermediate drying rate was achieved using impingement drying, and the lowest using infrared drying.