Assessment of temperature gradient effects on moisture transfer through thermogradient coefficient
Résumé
The objective of this paper is to describe moisture transfer through porous material due to temperature gradient. For that purpose, an experimental device was set-up to assess moisture flux under isothermal and non-isothermal conditions. This involves placing samples between two compartments with controlled air conditions and monitoring relative humidity and temperature profiles inside the samples over the time. To interpret these results, we proposed to express the mass flux in terms of two driving potentials: water vapor content gradient and temperature gradient. Accordingly, thermogradient coefficient was calculated and discussed. It represents the difference between the moisture fluxes under isothermal and non-isothermal conditions. The impact of temperature gradient on the Moisture Buffer Value (MBV) was also considered through a numerical experiment taking into account thermogradient coefficient. Results show that temperature gradient implies a relative variation of the MBV for about14% .Thus, it would be better to consider non-isothermal conditions for its assessment. Keywords: Non-isothermal transfer, thermogradient coefficient, Experimental, MBV, building material