Internal diffusion transfer of moisture during birch veneer filtration drying

Abstract

The technology of veneer production is a multistage, energy intensive and the drying stage is characterized by the highest energy costs. The authors proposed a filtration drying of packed birch veneer, which allows maximizing the heat agent drying potential, and, respectively, compared with the existing equipment, reducing energy costs for the drying process and ensuring high quality of dried veneer. The moisture transfer phenomena during packed veneer drying are defined as laws of both the external diffusion and internal diffusion processes. The solution of the differential equation of internal diffusion for a thin plate of finite sizes for the boundary conditions of the first type is given, on the basis of which the internal moisture diffusion coefficient from the veneer sheets is defined and its dependence on temperature is determined. The dependencies, given in the paper make it possible to predict the dependence of the filtration drying process of packed sliced birch veneer and at the design stage of a new drying equipment to establish economic feasibility of the process modernization.