Improving the performance of mini-channel heat sink by using wavy channel and different types of nanofluids.

The combination of nano fluid and changing cross-section mini-channel heat sink effects have become a remarkable choice for the use of thermal devices such as miniature electronic devices to be effectively cooled. In this paper, the comparison of three dimensional straight and wavy channel configuration with using different types nano fluids are numerically investigated. The effects of wave amplitude and A particular type of volume fraction of (Copper Oxide CuO, Dimond Al2O3, Iron Oxide Fe3O4, Titanium Oxide TiO2 and Silver Ag-nano fluids are offered. Three amplitudes of waves (0.15 mm, 0.2 mm and 0.25 mm) and Reynold's number from 200 to 1000 and concentration volume varieties from 0 to 0.075 are used. The effect on thermal resistance, pressures drop, factor of friction of the mini channel is displayed. It is observed that the mini-channel sink's heat transfer efficiency is greatly enhanced compared to the straight channel in an event of adding distilled water as accoolant. The results indicate that nano fluid and wavy mini-channel can boost the heat sink's hydrothermal efficiency and Ag- water nano fluid in term of heat transfer, it outperforms other nanofluids an enhancement in the Nusselt number reached to 54% at concentration volume 0.075.

MHD mixed convection and entropy generation of CNT-water nanofluid in a wavy lid-driven porous enclosure at different boundary conditions.

In this study, Galerkin Finite Element Method or GFEM is used for the modeling of mixed convection with the entropy generation in wavy lid-driven porous enclosure filled by the CNT-water nanofluid under the magnetic field. Two different cases of boundary conditions for hot and cold walls are considered to study the fluid flow (streamlines) and heat transfer (local and average Nusselt numbers) as well as the entropy generation parameters. Richardson (Ri), Darcy (Da), Hartmann angle (γ), Amplitude (A), Number of peaks (N), Volume fraction (φ), Heat generation factor (λ), Hartmann number (Ha) and Reynolds number (Re) are studied parameters in this study which results indicated that at low Richardson numbers (< 1) increasing the inclined angle of magnetic field, decreases the Nu numbers, but at larger Richardson numbers (> 1) it improves the Nu numbers.

Magnetic nanofluid behavior including an immersed rotating conductive cylinder: finite element analysis.

In this paper, numerical Galerkin Finite Element Method (GFEM) is applied for conjugate heat-transfer of a rotating cylinder immersed in Fe3O4-water nanofluid under the heat-flux and magnetic field. The outer boundaries of the cavity were maintained at low temperatures while beside the cylinder were insulated. It is assumed that the cylinder rotates in both clockwise and counter-clockwise directions. The dimensionless governing equations such as velocity, pressure, and temperature formulation were analyzed by the GFEM. The results were evaluated using the governing parameters such as nanoparticles (NPs) volume fraction, Hartmann and Rayleigh numbers, magnetic field angle and NPs shapes. As a main result, the average Nusselt number increases by increasing the NPs volume fraction, inclination angle and thermal conductivity ratios, while increasing the Hartmann number decreased the Nusselt number. Furthermore, platelet NPs had the maximum average Nusselt number and spherical NPs made the minimum values of Nusselt numbers among examined NPs shapes.

MHD effect on mixed convection of annulus circular enclosure filled with Non-Newtonian nanofluid.

The fluid flow and mixed convection heat transfer of a non-Newtonian (Cu-water) nanofluid-filled circular annulus enclosure in a magnetic field are investigated numerically for a two-dimensional, steady-state, incompressible, laminar flow using the Galerkin finite element method (GFEM). The Prandtl number (Pr = 6.2) and Grashof number (Gr = 100) are assumed to be constants, whereas the Richardson number varies within a range of 0 ≤ Ri ≤ 1, the Hartman number within a range of 0 ≤ Ha ≤60, the Power law index within a range of 0.2 ≤ n ≤ 1.4, and the volume fraction within a range of 0 ≤ φ ≤ 1. The enclosure consists of an outer rotating cylinder that is kept at a cold temperature (Tc) and an inner non-rotating cylinder kept at a hot temperature (Th). The ratio of the inner circular diameter to the annulus space length is kept constant at 2. The results depict that the stream function increases with increasing power law index, even up to n = 1, which causes the fluid to behave as a Newtonian fluid. The magnetic field has a critical impact on the fluid flow pattern. The average Nusselt number increases with decreasing Richardson number, owing to the improved heat transfer by forced convection.