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Tunis, Tunisia

Touzri D.,LETTM | Bouterra M.,LETTM | Elcafcy A.,LETTM | Belghith A.,LETTM | Le Palec G.,CNRS IUSTI - University Institute of Thermodynamic Industrial Systems)
Materiaux et Techniques

In the present work, we investigate the melting process of phase-change material (PCM) such as paraffin wax. The study is carried out by an illustrative numerical exercise using an enthalpy-porosity method for modeling the melting process. The isotherms and the liquid-solid interface of the melting process, the impact of the hot temperature, the effect of the aspect ratio and of the inclination of the heating surfaces of a square cavity, the stored energy, and the melt fraction are studied and analyzed at different stages. The results showed that the energy was amplified with the increase in the temperature gap. The degree of the influence of convection was also increased by decreasing the aspect ratio. Finally, the melting fusion and the stored energy are better for vertical wall heating than for horizontal bottom wall heating. © 2014 EDP Sciences. Source

Fatma H.,LETTM | Afif E.K.,LETTM | Oueslati F.S.,Ecole de Technologie Superieure of Montreal
Proceedings - International Conference on Solar Energy and Building, ICSoEB 2015

3D Natural convection in partially porous media. The Study focused on transfers and flow in porous media in nonequilibrium. Darcy-Brinkman model's is adopted. Moreover the two-equation model is used to separately account for the local fluid and solid temperatures. A numerical method based on the finite volume method a full multigrid technique is employed. We find the impact of the conductivities ratio on the flow and the heat transfer. © 2015 IEEE. Source

Oueslati F.S.,LETTM | Bennacer R.,Ecole Normale Superieure de Cachan | Sammouda H.,University of Sousse | El Ganaoui M.,Institut Universitaire de France
Numerical Heat Transfer; Part A: Applications

A shallow horizontal cavity filled with two layers of nonmiscible fluids, is studied both analytically and numerically. The upper free surface of the layer is subject to a shear stress. The analytical solution, based on the parallel flow approximation, is found to be in good agreement with a numerical solution. The existence of both natural and antinatural flows is demonstrated. Indeed, the critical Rayleigh number for the onset of motion is dependent on the side heating intensity. Multiple steady state solutions are possible in a range of the rate of fluids dynamics viscosity that depends strongly on the upper fluid one. © 2012 Copyright Taylor and Francis Group, LLC. Source

Madiouli J.,LETTM | Sghaier J.,LETTM | Lecomte D.,Toulouse 1 University Capitole | Sammouda H.,LETTM
Food and Bioproducts Processing

Based on a very simple model of mass conservation, three experimental properties (solid density, liquid density and initial bulk density) and the simultaneous acquisition of the reduced moisture content and the volume shrinkage during drying, a simple method is proposed to calculate the bulk porosity of a material during drying. This model allows a graphical interpretation to visualize the porosity change by comparing the experimental shrinkage curve with an ideal shrinkage curve. In the present work, several examples were taken from the literature to illustrate the application of this method to foodstuffs (apple, banana, carrot, garlic, pear, potato and sweet potato) with two different processes (convective drying, freeze-drying) and different drying conditions. Porosity calculations including error estimations showed a good agreement with experimental values reported in the literature. © 2011 The Institution of Chemical Engineers. Source

Amel K.,LETTM | Fakhreddine O.,Ecole de Technologie Superieure of Montreal | Rachid B.,Ecole Normale Superieure de Cachan | Afif E.,LETTM
Defect and Diffusion Forum

The present work aims to study convection and heat transfer and mass in a porous cubic cavity. The configuration considered is a cavity cube with vertical walls left and right are subjected to temperatures required while others are impermeable and adiabatic. We realized that the results depend on several characteristic parameters, and general correlations are established for the calculation of heat and mass transfer, according to various studied parameters. The study focuses on the influence of the control parameters on the structure of the flow, heat and mass transfer.© (2014) Trans Tech Publications, Switzerland. Source

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