THE INFLUENCE OF KILN GEOMETRY ON FLOW MALDISTRIBUTION ACROSS TIMBER STACKS IN KILNS

ABSTRACT

A one-dimensional mathematical model is evaluated for flow through a timber-drying kiln. This model is used to develop recommendations for the design of the plenum chambers on either side of the timber stack. The variation of the vertical air velocity was explored for a sticker spacing of 20 mm and a board thickness of 50 mm. When the width of the plenum chambers is at least equal to the sum of the thickness of the stickers, flow maldistribution is substantially reduced in single-track kilns. The width of the plenum chambers of double-track kilns may be reduced to three-quarters of the sum of the thickness of the stickers, because the increase in timber-stack resistance to airflow mitigates the effect of pressure variations down the length of the plenum chambers.

Key Words and Phrases:

• fluid dynamics
• kiln design
• lumber
• manifold
• plenum chamber.