Experimental Determination Of The Ratio Of Vapor Diffusion To The Total Water Movement In Wood During Drying

Carl Tremblay, Alain Cloutier, Bernard Grandjean

Abstract


The knowledge of the ratio ϵ of vapor diffusion to the total water movement in wood during drying is necessary when phase change is considered in the heat transfer equation of a wood-drying model based on water potential. An original experimental method was developed to determine the ratio ϵ. The method is based on the measurement of temperature and moisture content profiles in wood during drying and the calculation of total enthalpy profiles.

ϵ was determined from drying experiments of red pine sapwood (Pinus resinosa Ait.) in the radial direction at 18, 56, and 85°C. The experimental results show that ϵ increases from 0.15 to 0.5 as moisture content decreases from values close to saturation (160%) to about 15%. ϵ reaches a plateau at about 0.33 for intermediate moisture contents (35 to 120%).


Keywords


Wood drying;model;heat transfer;vapor diffusion

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