Numerical analysis of conjugate porous media for increasing heat transfer rate in fixed bed spheres

2019 ◽  
Author(s):  
Farida Rahmawati Purnadiana ◽  
Prabowo ◽  
Herman Sasongko
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
Numerical Analysis ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Fixed Bed

Effect of Microscopic Vortices Caused by Flow Interaction With Solid Obstacles on Heat Transfer in Turbulent Porous Media Flows

2019 ◽  
Author(s):  
Ching-Wei Huang ◽  
Vishal Srikanth ◽  
Haodong Li ◽  
Andrey V. Kuznetsov
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Porous Medium ◽  
Porous Media ◽  
Heat Transfer Rate ◽  
Contact Area ◽  
Transfer Rate ◽  
Porous Media Flow ◽  
Pore Scale ◽  
Solid Obstacles

Abstract Turbulent flow in a homogeneous porous medium was investigated through the use of numerical methods by employing the Reynolds Averaged Navier-Stokes (RANS) modeling technique. The focus of our research was to study how microscopic vortices in porous media flow influence the heat transfer from the solid obstacles comprising the porous medium to the fluid. A Representative Elementary Volume (REV) with 4 × 4 cylindrical obstacles and periodic boundary conditions was used to represent the infinite porous medium structure. Our hypothesis is that the rate of heat transfer between the obstacle surface and the fluid (qavg) is strongly influenced by the size of the contact area between the vortices and the solid obstacles in the porous medium (Avc). This is because vortices are regions with low velocity that form an insulating layer on the surface of the obstacles. Factors such as the porosity (φ), Pore Scale Reynolds number (Rep), and obstacle shape of the porous medium were investigated. All three of these factors have different influences on the contact area Avc, and, by extension, the overall heat transfer rate qavg. Under the same Pore Scale Reynolds number (Rep), our results suggest that a higher overall heat transfer rate is exhibited for smaller contact areas between the vortices and the obstacle surface. Although the size of the contact area, Avc, is affected by Rep, the direct influence of Rep on the overall heat transfer rate qavg is much stronger, and exceeds the effect of Avc on qavg. The Pore Scale Reynolds number, Rep, and the mean Nusselt number, Num, have a seemingly logarithmic relationship.

Convective Heat Transfer of Al2O3 Nanofluids in Porous Media

2016 ◽  
Vol 139 (3) ◽  
Author(s):  
Navid O. Ghaziani ◽  
Fatemeh Hassanipour
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Porous Medium ◽  
Porous Media ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Particle Concentration ◽  
Metal Foam ◽  
Volume Fraction ◽  
Constant Heat Flux

In this study, the performance of a heat sink embedded with a porous medium and nanofluids as coolants is analyzed experimentally. The nanofluid is a mixture of de-ionized water and nanoscale Al2O3 particles with three different volumetric concentrations: ζ = 0.41%, 0.58%, and 0.83%. The experimental test section is a rectangular minichannel filled with metal foam, which is electrically heated to provide a constant heat flux. The porous medium is assumed to be homogeneous and the flow regime is laminar. The result of heat transfer enhancement by slurry of Al2O3 nanofluid in porous media is studied under various flow velocities, heat flux, porous media structure, and particle concentration of nanofluid. The effect of particles volume fraction on heat transfer coefficient is also studied. This experimental study discovers and/or confirms the following hypotheses: (1) nanoparticle slurry in conjunction with metal foam has a significant effect on heat transfer rate; (2) there is an optimum permeability for the foam resulting in maximal heat transfer rate; (3) for a fixed particle concentration, smaller particles are more effective in enhancing heat transfer; and (4) increasing particle concentration results in some gains, but this trend weakens after a threshold.

Experimental Analysis of Nanofluid Slurry Through Rectangular Porous Channel

2012 ◽  
Author(s):  
Navid O. Ghaziani ◽  
Fatemeh Hassanipour
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Porous Media ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Metallic Nanoparticles ◽  
Metal Foam ◽  
Nano Particles ◽  
Aluminum Oxide Nanoparticles ◽  
Efficient Heat Transfer

One of the limitations in evolution of energy-efficient heat transfer fluids in industrial application is their low thermal conductivity. Among the emerging heat transfer technologies of today are fluid additives based on metallic nanoparticles. Previous studies show that Matalic nano particles increase the heat transfer rate by their thermal conductivity. This experimental study investigates the heat transfer behavior of nanofluid slurry through metal foam. Using suspending Aluminum Oxide nanoparticles (AL2O3) in fluid flowing through porous medium leads to have an even greater augmentation in heat transfer rate. Metal foams (porous media) enhance heat transfer rate not only by their high thermal conductivity and also by their mixing effect. When these two subjects come together even more interesting behaviors happen. This paper presents the result of heat transfer enhacment by slurry of metal nanoparticles in porous media in various of flow velocities, heat flux and porous media structures e.g. PPI and particle concentration of nanofluid.

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