Abstract
Natural convection of nanoliquid in a square porous enclosure has been studied using non homogeneous two-phase Buongiorno’s model. The outer of enclosure has cold temperature and a circular cylinder is put at the center. A finite heated segment is located on the top cylinder surface which is otherwise insulated. The momentum in the porous layer is modeled applying the Brinkman-Forchheimer equations. The analysis are conducted in the following interval of the associated groups: the portion of heated surface (5% ≤ H ≤ 100%), the concentration (0.0 ≤ ϕ ≤ 0.04), the Darcy number, 10−5 ≤ Da ≤ 10−2 and the cylinder size, (0.15 ≤ R ≤ 0.25). The minimum heat transfer rate of the active surface were obtained at location ξ = 90°. In general, the ratio of the heat transfer per unit area of the heat source decreases as the length of the heated surface increases. The heat transfer rate is intensified for the half thermally active surface and high value of Darcy number at higher nanoparticles concentration.
Highlights
Management convection heat transfer becomes an important aspect in thermal device such as handled devices, electronic equipments and heat exchangers
The multi-phase model assumes the slip velocity between the liquid phase and the solid, so that the multi-phase nanoliquid model confirmed to be more realistic the Buongiorno’s multi-phase nanoliquid model together with the Brownian motion and thermophoresis effects were studied by[19]. They reported that the Nusselt number is increasing functions of the ration of heating intensity and thermophoresis parameters but decreasing functions of the the ratio of thermal diffusivity and Brownian motion parameters[20]
It may be due to the fact that at high Darcy numbers where porosities enlarge, more particles are diffused within recirculating zones and more deposition happen especially in the zone under the cylinder
Summary
Management convection heat transfer becomes an important aspect in thermal device such as handled devices, electronic equipments and heat exchangers. The multi-phase model assumes the slip velocity between the liquid phase and the solid, so that the multi-phase nanoliquid model confirmed to be more realistic the Buongiorno’s multi-phase nanoliquid model together with the Brownian motion and thermophoresis effects were studied by[19] They reported that the Nusselt number is increasing functions of the ration of heating intensity and thermophoresis parameters but decreasing functions of the the ratio of thermal diffusivity and Brownian motion parameters[20]. The active cylinder embedded in the center of the deferentially heated enclosure studied by[29,30] filled the porous enclosure with a water-based nanoliquid suspending Ag, Cu, Al2O3, or TiO2 solid nanoparticles. They searched the optimum cylinder radius and applied the Darcy flow with the Tiwari and Das nanoliquid models. The continuity, momentum, thermal energy, nanoparticles and nanoparticles mass flux equations can be stated as follows:
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