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International audience; In this paper, we report an experimental study on an empty dryer. The device under is an indirect dryer electrically heated. The focus is made on the thermal and fluid behavior in such systems without considering the drying process. Thus, the temperature and fluid velocity profiles are presented in order to determine the fluid flow and the thermal profiles inside the different parts of the dryer in the situations of natural and mixed convection in order to describe and allow a better comprehension of the heat and fluid flow patterns inside a dryer. The enthalpy balances lead to the determination of the most efficient zone in the dryer, this latter is located at 2/3 of its length.

International audience; Numerical investigation of the natural convection of !" ! # "-water nanofluid is carried out in a differentially heated vertical annulus under a uniform magnetic field. An in-house Fortran code has been developed to solve the system of equations governing the magneto-hydrodynamic flow. Computations are carried out for different Rayleigh numbers (10 # ≤ '(≤ 10 $), nanoparticle diameter () % = 13 and 47 /0), nanoparticle volume fraction (0 ≤ 3 ≤ 0.09), radius ratio (2 ≤ 7 ≤ 10), and different Hartmann numbers (0 ≤ 8(≤ 100). According to the simulation data, nanoparticle size is crucial for evaluating nanofluid properties, such as viscosity and thermal conductivity. The computational results reveal that, for nanoparticles with a diameter) % = 47 /0, the average Nusselt number 9: ;;;; & on the inner cylinder wall decreases as the nanofluid volume fraction increases. This decrease in 9: ;;;; & number is observed up to a volume fraction 3 = 0.05, after which it increases again. For the full range of volumetric fractions, it is shown that increasing '(number causes 9: ;;;; & to increase, while increasing 8(number and increasing the magnetic field causes 9: ;;;; & to decrease. Furthermore, as the 8(number increases, the heat transfer enhancement ratio =/ increases mainly when the magnetic field is oriented radially. Finally, new correlations of 9: ;;;; & versus '(, 3, 8(, and 7 are derived for the axial and radial magnetic fields cases.

Colloque avec actes et comité de lecture. Internationale.; International audience; Le comportement tribologique, du pion en matériau paramagnétique (aluminium), glissant sur un disque tournant en matériau ferromagnétique (acier XC48), en présence du champ magnétique alternatif extérieurement appliqué, avec passage du courant électrique continu ont été étudié. Les essais ont été réalisés sur un tribomètre, type pion-disque. En effet, la caractérisation structurale des surfaces en contact, des oxydes et des débris d'usure, par diffraction des rayons X (angle θ -2 θ), a montré l'effet marqué du champ magnétique sur l'activation de la surface de contact du pion en matériau non ferromagnétique. L'absence du champ magnétique engendre un changement du mode d'usure, et on assiste à une transition du mode doux (usure par oxydation) à un mode abrasif sévère.

In this work, we numerically studied the influence of the partitions on the transfer of heat by natural convection and thermal radiation in a tilted cavity of an angle φ = 45° compared to the horizontal plane. The equations controlling the system are solved by the method of finished volumes. The cavity contains a number of partitions varying from 0 to 3. We concluded that: i) the thermal radiation increases the transfer of heat within the cavity, ii) more number of partitions is large, plus the transfer of heat is reduced, Dans ce travail, nous avons étudié numériquement l'influence des partitions sur le transfert de chaleur par convection naturelle et par rayonnement thermique dans une cavité inclinée d'un angle par rapport au plan horizontal. Les équations gouvernant le système sont résolues par la méthode des volumes finis. La cavité contient un nombre de partitions variant de 0 à 3. Nous avons conclu que: i) le rayonnement thermique augmente le transfert de chaleur au sein de la cavité, ii) plus le nombre de partition est grand, plus le transfert de chaleur est réduit.

International audience; This paper deals with three-dimensional, mixed convection in a cylindrical duct horizontally. This latter is partially subjected to a uniform volumetric heat generation at the solidliquid interface. The working fluid (water) with a parabolic velocity profile and a constant temperature T0 enters the tube. The study was carried out for different Richardson numbers values Ri=0.1-8 at Reynolds number Re=600. Results were conducted so that to show the influence of Richardson number Ri on the dynamic and thermal fields and local Nusselt number Nu(q,z) and peripherally averaged axial Nusselt number Nu(z). Also, analyses of the results showed that the hydrodynamic effects are manifested by the existence of secondary flow, inducing temperature gradient at a crosssection between the top and bottom of the duct. The reversed flow is observed for a low Reynolds number Re=10. A significant increase in heat exchange is observed in mixed convection compared to pure forced convection flow. Correlations for the variation of average Nusselt number Nu (Ri,z) at the entrance region with Ri and z=z¢/Di and local Nusselt Nu(Ri) number in the hydrodynamics establishment zone are proposed and compared with the present numerical results.