Effect of conjugate heat transfer on flow of nanofluid in an enclosure with heat conducting vertical wall and uniform heat flux

Abstract

An elaborate numerical study of developing a model regarding conjugate effect of fluid flow and heat transfer in a heat conducting vertical walled cavity filled with copper-water nanofluid has been presented in this thesis. This model is mainly adopted for a cooling of electronic device and to control the fluid flow and heat transfer mechanism in an enclosure. The numerical results have been provided in graphical form showing effect of various relevant non-dimensional parameters. The relevant governing equations have been solved by using finite element method of Galerkin weighted residual approach. The analysis uses a two dimensional rectangular enclosure under conjugate convective conductive heat transfer conditions. The enclosure exposed to a constant and uniform heat flux at the left vertical thick wall generating a natural convection flow. The thicknesses of the remaining parts of the walls are assumed to be zero. The right wall is kept at a low constant temperature, while the horizontal walls are assumed to be adiabatic. A moveable divider is attached at the bottom wall of the cavity. The governing equations are derived for the conceptual model in the Cartesian coordinate system. Firstly, conjugate heat transfer in a rectangular enclosure filled with nanofluid is numerically investigated. Study have been carried out for the solid volume fraction 0 ≤ 𝜙 ≤ 0.05. The effects of Rayleigh number, the value of convective heat transfer coefficient, location of the divider position, the solid fluid thermal conductivity ratio and thickness of solid wall on the hydrodynamic and thermal characteristic of flow have been analyzed. Results are presented in the form of streamlines, isotherms and average Nusselt number. An increase in the average Nusselt number was found with the solid concentration for the whole range of Rayleigh number. In addition, the obtained results show a considerable effect on the heat transfer enhancement. In particular it is interesting to mention that divider can be located inside the partition to control heat transfer especially in electronic device. Secondly, the numerical solution will also be carried out for the problem of MHD conjugate natural convection flow in a rectangular enclosure filled with electrically conducting fluid. The effect of Hartmann number on the pertinent parameters on the flow and temperature fields and heat transfer performance of the enclosure will also be examined. It is expected that the heat transfer rate will increase with an increase of Rayleigh number, divider position and solid fluid thermal conductivity ratio, but it should viii decrease with an increase of the Hartmann number. It is also expected that an increase of the solid volume fraction will enhance the heat transfer performance.