1-11
Influence of Thermal Radiation on Steady Mixed Convection inside a Multiple Vented Cavity subjected to Sucked or Injected External Flow
Khadija Ezzaraa, Ahmed Bahlaoui, Abdelghani Raji, Mohammed Hasnaoui
[Abstract]
Abstract: A numerical study is carried out to investigate the interaction between mixed convection and thermal radiation in a horizontal ventilated enclosure. Air, a radiatively transparent medium, is admitted into the cavity by injection or suction, by means of two openings placed on the lower part of both right and left vertical sides. Another opening is located on the middle of the top wall to ensure the ventilation. The parameters governing the problem are the Reynolds number, Re, and the emissivity of the walls, ε. The effect of these parameters on flow and thermal fields as well as on the heat transfer rate within the enclosure is examined for the two ventilation modes (injection and suction). Variations, versus the main controlling parameters, of maximum and mean temperatures are also presented. The results indicate, for the two modes of imposed flow, that the thermal radiation affects the flow and thermal structures. Also, it is found that the radiation enhances the global heat transfer so that its contribution is more considerable even for the high values of Re. However, the suction mode is found to be more favorable to the heat transfer in comparison with the injection one.
Key words: Surface radiation, Mixed convection, numerical study, vented cavity, injection, suction
12-20
Heat Transfer Performance of Homogenous Nanofluids Under Mixed Convection in a Vented Cavity with Linearly Varying Wall Temperature
Abdelhak Daiz, Ahmed Bahlaoui, Ismail Arroub, Abdelghani Raji, Mohammed Hasnaoui
[Abstract]
Abstract: The present work consists to investigate numerically the mixed convection heat transfer in a multiple vented enclosure, confining alumina-water nanofluid, with inlet and outlet ports due to the suction of leaving flow. The bottom wall is subjected to a linearly varying decreasing heat, whereas the other boundaries are assumed to be thermally insulated. The consequence of varying the Reynolds number, 200 ≤ Re ≤ 5000, and nanoparticles concentration, 0 ≤ Φ ≤ 0.07, on the dynamical and thermal characteristics of the flow and heat transfer performances are investigated and discussed. The obtained results show that the presence of nanoparticles enhances the heat transfer across the cavity and promotes the reheating of this latter. Morever, a comparative study shows that the decreasing temperature profile has the same thermal performance as that of a uniform temperature profile.
Key words: Mixed convection, nanofluid, decreasing heating, multiple vented cavity, suction.
