On Local Temperature Overshoots Due to Transport Coupling of Heat and Moisture in Composite Materials

Abstract

An analysis of coupled heat and moisture transfer in composite materials is presented. The moisture and heat fluxes are described by linear phenomenological laws including the transport coupling contributions of thermal-diffusion (Soret effect), and diffusion-thermo (Dufour effect). The present mathematical approach is based on a field transformation for the enthalpy and moisture concentration which enables one to minimize the number of nondimensional groups for the transport coupling coefficients which are then determined by comparison of the theoretical results with given ex perimental data. New solutions are presented for transient temperature distributions in an infinite moist slab of a finite thickness, subject to a step change in surface tem perature and moisture concentration. These solutions indicate that local temperature overshoots may occur within the slab close to the surface, due to the heat-moisture transport coupling. Such temperature overshoots have also been observed in ex periments reported by Luikov and the present solutions show good agreement with the reported experimental data.

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