Walnut and American walnut wood impulse drying in convective drying tunnels

A review of the literature on the physical and mechanical properties of the walnut and the scope of its application is presented. Pilot drying of walnut wood with a thickness of 50…60 mm was carried out in modernized drying chambers using impulse drying modes URAL-72 at INTAR LLC, Moscow. An example of an impulse drying mode for a walnut with a thickness of 50…60 mm is given. The initial moisture content of wood was determined in accordance with GOST 16558–91. The physical and mechanical properties of American walnut are outlined. The drying mode of American walnut 32…35 mm thick included 9 steps. The temperature of the drying agent is from 49 °C to 83 °C. The degree of saturation of the drying agent is from 79 to 31 %. Impulse drying of American walnut wood with a thickness of 32…35 mm was carried out in a pilot drying tunnel at the Department of Wood Science and Woodworking Technology of Moscow State Forest University. The initial moisture content of American walnut wood was determined in accordance with GOST 16588–91. The control over the current moisture content and internal stresses in the wood of walnut and American black walnut during drying in impulse modes was carried out using the method of control samples. Determination of the quality of dried timber was carried out in accordance with the «Guiding technical materials on the technology of tunnel drying of sawn timber» and the technical conditions of GOST 2695–83. The use of impulse modes when drying walnut and American walnut wood allows saving from 30 to 50 % of electricity.