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Title:	Fluid flow and heat transfer in enclosures partially- or fully-filled with nanofluids
Authors:	Ammar Ibraheem Abed Alsabery (P72856)
Supervisor:	Ishak Hashim, Prof. Dr.
Keywords:	Non-equilibrium Fluid flow Heat transfer Nanofluids Dissertations, Academic -- Malaysia
Issue Date:	8-Nov-2016
Description:	Understanding of fluid flow patterns and convective heat transfer processes in complex geometries is one of the most important issues in recent years due its wide range of industrial and engineering applications. To achieve an optimal heat transfer process in advanced energy systems by increasing or decreasing the heat transfer rate is a major question for scientists or engineers. To answer the question, conjugate heat transfer, non-equilibrium energy system, geometry orientation and partially-filled porous media enclosures are simulated numerically in this work. A differentially heated square, trapezoidal and oblique enclosures are selected as geometrical models. The flow is assumed to be Newtonian, non-Newtonian, two-dimensional, incompressible and laminar. Nanoparticles are assumed in a spherical shape. As for the porous medium, Darcy law and Brinkman-extended Darcy models are assumed to hold and the porous material is taken to be homogenous and isotropic. The governing equations and boundary conditions are nondimensionalised to form a system of nonlinear partial differential equations. Two techniques have been used to solve the final equations, one coded in MATLAB where an algorithm consisting of a finite difference method with an alternating direct implicit scheme and a tridiagonal matrix algorithm or Gaussian successive over-relaxation scheme and another technique by finite element method in COMSOL. The numerical results of the flow and temperature fields as well as the heat transfer rates are presented graphically. First, we have considered the effects of spatial side-wall temperature variations on natural convection of a nanofluid in a trapezoidal enclosure. The results show that the strength of the flow circulation is clearly enhanced by the nanofluid addition due to the higher thermal conductivity of the nanoparticles. Optimal heat transfer performances are obtained for a higher side wall inclination angle or silver nanoparticles with high volume fraction of the trapezoidal enclosure. Next, the problem of natural convection in an inclined square enclosure partly filled with a porous layer and saturated by a nanofluid with sinusoidal temperature boundary conditions is studied numerically. The obtained results show that the heat transfer rate is significantly influenced by the porous layer increment. Different nanoparticles depicted a variety of enhancements on the convection heat transfer. Finally, we study the problem of transient natural convection heat transfer in nanofluid-saturated porous oblique enclosure using thermal non-equilibrium model. Results show that the strength of the flow circulation increases for the relative concentration of nanofluid with the increment of the inclination angle in the positive direction. Furthermore, a significant increment in the convection heat transfer is obtained with a higher porosity.,Certification of Master's/Doctoral Thesis" is not available
Pages:	254
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Science and Technology / Fakulti Sains dan Teknologi

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