Experimental study of the dynamic behaviour of a porous medium submitted to a wall heat flux in view of thermal energy storage by sensible heat

This study concerns the storage of thermal energy in a porous bed mainly formed by a vertical channel, filled with glass beads, heated on one of the vertical walls by a constant heat flux. The use of glass beads is motivated by the possible use of such a system for storage of solar energy by sensitive heat and its optimization. The medium is characterized by a large thermal inertia which favors a slow return of the heat stored during the heating phase. After model reduction, the system can be dynamically modeled as a simple first order which allows us to evaluate the heat transfer coefficient and to predict its response to real values of the solar flux. The system efficiency defined as the ratio of the stored energy to the energy provided increases with the storage volume and decreases with the return time for fixed width and storage time. (c) 2006 Elsevier Masson SAS. All rights reserved.