Mass and heat transfer mechanism in wood during radio frequency/vacuum drying and numerical analysis

Abstract

The mass and heat transfer mechanisms during radio frequency/vacuum (RF/V) drying of square-edged timber were analyzed and discussed in detail, and a new one-dimensional mathematical model to describe the transport phenomena of mass and heat during continuous RF/V drying was derived from conservation equations based on the mass and heat transfer theory of porous materials. The new model provided a relatively fast and efficient way to simulate vacuum drying behavior assisted by dielectric heating. Its advantages compared with the conventional models include: (1) Each independent variable has a separate control equation and is solved independently by converting the partial differential equation into a difference equation with the finite volume method; (2) The calculated data from different parts of the specimen can be displayed in the evolution curves, and the change law of the parameters can be better described. After analyzing the calculated results, most of the important phenomena observed during RF/V drying were adequately described by this model.

Keywords

Bulk flow / Mathematical model / Numerical analysis / RF/V drying transfer mechanism

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