Enhancement of heat transfer coefficient and flow in tube filled with a porous medium by using hybridnan of luidsh

الملخص EN

This research involved the enhancement of heat transfer and flow in a tube filled with a porous medium by using hybrid nanofluids.

The theoretical model contains the governing equations to the flow and heat transfer through porous media by using the Darcy flow model with uniform heat flux on the surface tube.

The porous medium consist of glass beads (dp = 20 mm) and one type of filling material.

The simple algorithm is used to solve momentum and continuity equations after combined these equations to configure the pressure correction formula.

The results of this study represented by different parameters such as Rayleigh number (Ra=103,105,106), type of hybrid nanoparticles,volume fraction (Φ =1, 3 and 5% vol), and angles of tube (α =300, 450 and 900) through contour secondary flow and isotherms.

The results also show that average Nussult number various with Rayleigh number, type of the hybrid nanoparticles and constant of Peclet number ( Pe =20).

The results of numerical solution indicated that the impact of free convection appears at the start region of the tube and its maximum impact happen in the horizontal position then this effect decreases to the vertical position when inclination of the tube increses.

Moreover the concentration of hybrid nanoparticles has an insignificant impact on the stream lines, tangential and radial velocities distribution, skin friction coefficient and porous media.

The heat transfer increases with the increase concentration of hybrid nanoparticles and Rayleigh number.

On the other hand the type and synergistic of hybrid nanoparticles play important role in improvement of heat transfer.

The improvement for hybrid nanofluid is (Cu(25nm)+Al(25nm)+Dw) (33%) while for hybrid nanofluid it is (Al2O3(50nm)+TiO2 (50nm)+Dw) was (24%) respectively.