AIRFLOW BEHAVIOUR IN TIMBER (LUMBER) KILNS

Even drying of stacked timber boards in a kiln depends, amongst other things, on having a uniform airflow through the pile. A study of possible airflow maldistribution in existing kilns has been carried out using a Perspex model of a kiln, with water as the fluid, which has been designed to be geometrically similar to an actual kiln and have dynamically similar flows. Measurements of local velocities were possible by tracing the flow of fine gas bubbles. The standard kiln arrangements result in significant recirculation zones before and after the stack, with a non-uniform incident velocity profile. Different design alternatives for the geometry of the plenum spaces on either side of the stack have been investigated.