Convective Mass Transfer Coefficients for Gypsum and Wood Paneling

Abstract

This paper presents the measured convective mass transfer coefficients for humid air flowing above an initially dry gypsum and wood panel (equilibrium with 30 % RH air) in the transient moisture transfer (TMT) facility at the University of Saskatchewan. The convective coefficients are measured during laminar flow at three different Reynolds numbers (Re=800, 1500, and 2100) and with three different humidities in the air stream (50, 70, and 90 % RH). The results show that the measured mass transfer coefficients are lower than the values measured above an open water surface by Iskra and Simonson in a previous work. For gypsum, the convective mass transfer coefficient varies from 0.0016 to 0.0033 m/s (1.2×10−8 to 2.4×10−8 s/m) with 95 % confidence uncertainty bounds ranging from ±20 to ±57 %. For wood, the convective mass transfer coefficient varies from 0.0001 to 0.0008 m/s (9.4×10−10 to 5.7×10−9 s/m) with 95 % confidence uncertainty bounds ranging from ±50 to±300 %. The experimental data are analyzed with a 1-D heat and mass transfer numerical model to check the discrepancy with the experimental data. The uncertainty associated with an indirect determination of mass transfer coefficient is discussed.

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