Microtomography-Based Analysis of Pressure Drop and Heat Transfer Through Open Cell Metal Foams

2013 ◽  
Author(s):  
M. Oliviero ◽  
S. Cunsolo ◽  
W. M. Harris ◽  
M. Iasiello ◽  
W. K. S. Chiu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Metal Foam ◽  
High Surface ◽  
Thermal Characteristics ◽  
Industrial Applications ◽  
Metal Foams ◽  
Surface Evolver ◽  
Periodic Cell ◽  
Numerical Predictions

Their light weight, open porosity, high surface area per unit volume and thermal characteristics make metal foams a promising material for many industrial applications involving fluid flow and heat transfer. Pressure drop and heat transfer of porous media have inspired a number of experimental and numerical studies. Many models have been proposed in the literature that correlate the pressure gradient and the heat transfer coefficient with the mean cell size and porosity. However, large differences exist among results predicted by different models. Most studies are based on idealized periodic cell structures. In this study, the true 3-D micro-structure of the metal foam is obtained by employing x-ray computed microtomography (XCT). For comparison, ideal Kelvin foam structures are developed in the free-to-use software “Surface Evolver” surface energy minimization program. Pressure drop and heat transfer are then investigated using the CFD Module of COMSOL® Multiphysics code. A comparison between the numerical predictions from the real and ideal geometries is carried out.

Numerical Analysis of Heat Transfer and Pressure Drop in Metal Foams for Different Morphological Models

2014 ◽  
Vol 136 (11) ◽  
Author(s):  
Marcello Iasiello ◽  
Salvatore Cunsolo ◽  
Maria Oliviero ◽  
William M. Harris ◽  
Nicola Bianco ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Pressure Drop ◽  
Metal Foam ◽  
High Surface ◽  
Industrial Applications ◽  
Metal Foams ◽  
The Real ◽  
Numerical Predictions ◽  
The Ideal

Because of their light weight, open porosity, high surface area per unit volume, and thermal characteristics, metal foams are a promising material for many industrial applications involving fluid flow and heat transfer. The pressure drop and heat transfer in porous media have inspired a number of experimental and numerical studies, and many models have been proposed in the literature that correlate the pressure gradient and the heat transfer coefficient with the mean cell size and porosity. However, large differences exist among results predicted by different models, and most studies are based on idealized periodic cell structures. In this study, the true three-dimensional microstructure of the metal foam is obtained by employing x-ray computed microtomography (XCT). This is the “real” structure. For comparison, ideal Kelvin foam structures are developed in the free-to-use software “surface evolver” surface energy minimization program. These are “ideal” structures. Pressure drop and heat transfer are then investigated in each structure using the CFD module of COMSOL® Multiphysics code. A comparison between the numerical predictions from the real and ideal geometries is carried out. The predictions showed that heat transfer characteristics are very close for low values of Reynolds number, but larger Reynolds numbers create larger differences between the results of the ideal and real structures. Conversely, the differences in pressure drop at any Reynolds number are nearly 100%. Results from the models are then validated by comparing them with experimental results taken from the literature. The validation suggests that the ideal structure poorly predicts the heat transfer and pressure drops.

Lord Kelvin and Weaire–Phelan Foam Models: Heat Transfer and Pressure Drop

2015 ◽  
Vol 138 (2) ◽  
Author(s):  
Salvatore Cunsolo ◽  
Marcello Iasiello ◽  
Maria Oliviero ◽  
Nicola Bianco ◽  
Wilson K. S. Chiu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Complex Geometry ◽  
Thermal Characteristics ◽  
Metallic Foams ◽  
Surface Evolver ◽  
Promising Tool ◽  
Numerical Predictions ◽  
Energy Equations ◽  
Lord Kelvin

The knowledge of thermal transport characteristics is of primary importance in the application of foams. The thermal characteristics of a foam heavily depend on its microstructure and, therefore, have to be investigated at a pore level. However, this analysis is a challenging task, because of the complex geometry of a foam. The use of foam models is a promising tool in their study. The Kelvin and the Weaire–Phelan foam models, among the most representative practical foam models, are used in this paper to numerically investigate heat transfer and pressure drop in metallic foams. They are developed in the “surface evolver” open source software. Mass, momentum, and energy equations, for air forced convection in open cell foams, are solved with a finite-element method, for different values of cell size and porosity. Heat transfer and pressure drop results are reported in terms of volumetric Nusselt number and Darcy–Weisbach friction factor, respectively. Finally, a comparison between the numerical predictions obtained with the two foam models is carried out, in order to evaluate the feasibility to substitute the more complex and computationally heavier Weaire–Phelan foam structure with the simpler Kelvin foam representation. Negligible differences between the two models are exhibited at high porosities.

Thermal Dispersion in Metal Foams

2011 ◽  
Author(s):  
Teresa B. Hoberg ◽  
Kenshiro Muramatsu ◽  
Erica M. Cherry ◽  
John K. Eaton
Keyword(s):  
Heat Transfer ◽  
Molecular Diffusion ◽  
Metal Foam ◽  
Heated Surface ◽  
High Surface ◽  
Metal Foams ◽  
Thermal Engineering ◽  
Transfer Model ◽  
Thermal Dispersion ◽  
Transverse Mixing

Open-cell metal foams are of interest for a variety of thermal engineering applications because of their high surface-to-volume ratio and high convective heat transfer coefficients relative to conventional fins. The tortuous flow path through the foam promotes rapid transverse mixing, a fact that is important in heat exchanger applications. Transverse mixing acts to spread heat away from a heated surface, bringing cooler fluid to the foam elements that are in direct contact with the surface. Heat is also spread by conduction in the foam ligaments. The present work addresses fully-coupled thermal dispersion in a metal foam. Dispersion of the thermal wake of a line source was measured. A conjugate heat transfer model was developed which showed good agreement with the data. The validated model was used to examine the complementary effects of the mechanical dispersion, molecular diffusion in the gas, and conduction in the solid.

scholarly journals Various Trade-Off Scenarios in Thermo-Hydrodynamic Performance of Metal Foams Due to Variations in Their Thickness and Structural Conditions

Energies ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 8343
Author(s):  
Trilok G ◽  
N Gnanasekaran ◽  
Moghtada Mobedi
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Flow Resistance ◽  
Metal Foam ◽  
Vertical Channel ◽  
Metal Foams ◽  
Hydrodynamic Performance ◽  
Pore Density ◽  
Trade Off ◽  
Topsis Technique

The long standing issue of increased heat transfer, always accompanied by increased pressure drop using metal foams, is addressed in the present work. Heat transfer and pressure drop, both of various magnitudes, can be observed in respect to various flow and heat transfer influencing aspects of considered metal foams. In this regard, for the first time, orderly varying pore density (characterized by visible pores per inch, i.e., PPI) and porosity (characterized by ratio of void volume to total volume) along with varied thickness are considered to comprehensively analyze variation in the trade-off scenario between flow resistance minimization and heat transfer augmentation behavior of metal foams with the help of numerical simulations and TOPSIS (Technique for Order of Preference by Similarity to Ideal Solution) which is a multi-criteria decision-making tool to address the considered multi-objective problem. A numerical domain of vertical channel is modelled with zone of metal foam porous media at the channel center by invoking LTNE and Darcy–Forchheimer models. Metal foams of four thickness ratios are considered (1, 0.75, 0.5 and 0.25), along with varied pore density (5, 10, 15, 20 and 25 PPI), each at various porosity conditions of 0.8, 0.85, 0.9 and 0.95 porosity. Numerically obtained pressure and temperature field data are critically analyzed for various trade-off scenarios exhibited under the abovementioned variable conditions. A type of metal foam based on its morphological (pore density and porosity) and configurational (thickness) aspects, which can participate in a desired trade-off scenario between flow resistance and heat transfer, is illustrated.

Geometric Mean of Fin Efficiency and Effectiveness: A Parameter to Determine Optimum Length of Open-Cell Metal Foam Used as Extended Heat Transfer Surface

2017 ◽  
Vol 139 (7) ◽  
Author(s):  
Tisha Dixit ◽  
Indranil Ghosh
Keyword(s):  
Heat Transfer ◽  
Metal Foam ◽  
Geometric Mean ◽  
Fluid Velocity ◽  
High Surface ◽  
Metal Foams ◽  
Heat Sinks ◽  
High Porosity ◽  
Open Cell ◽  
Fin Efficiency

High porosity open-cell metal foams have captured the interest of thermal industry due to their high surface area density, low weight, and ability to create tortuous mixing of fluid. In this work, application of metal foams as heat sinks has been explored. The foam has been represented as a simple cubic structure and heat transfer from a heated base has been treated analogous to that of solid fins. Based on this model, three performance parameters namely, foam efficiency, overall foam efficiency, and foam effectiveness have been evaluated for metal foam heat sinks. Parametric studies with varying foam length, porosity, pore density, material, and fluid velocity have been conducted. It has been observed that geometric mean of foam efficiency and foam effectiveness can be a useful parameter to exactly determine the optimum foam length. Additionally, the variation in temperature profile of different foams heated from one end has been determined experimentally by cooling these with atmospheric air. The experimental results have been presented for open-cell metal foams (10 and 30 PPI) made of copper/aluminium/Fe–Ni–Cr alloy with porosity in the range of 0.908–0.964.

A Parametric Investigation of Operating Limits in Heat Pipes Using Novel Metal Foams as Wicks

2010 ◽  
Author(s):  
Mahmood R. S. Shirazy ◽  
Luc G. Fre´chette
Keyword(s):  
Heat Transfer ◽  
Metal Foam ◽  
High Surface ◽  
Heat Pipes ◽  
Metal Foams ◽  
Dimensionless Number ◽  
Design Guideline ◽  
Parametric Investigation ◽  
Capillary Limit ◽  
Operating Limits

A parametric investigation has been performed to study the different operating limits of heat pipes employing a novel type of metal foam as wick for chip cooling applications. These foams have a unique spherical pore cluster microstructure with very high surface to volume ratio compared to traditional metal foams and exhibit higher operating limits in preliminary tests of heat pipes, suggesting high cooling rates for microelectronics. In the first part of this parametric study, widely used correlations are applied to calculate the five types of heat transfer limits (capillary, boiling, viscous, entrainment and sonic) as a function of temperature, type of foam, and porosity. Results show that the dominant limit is mostly the capillary limit, but for 50 pore-per-inch (PPI) foam, the boiling limit will be dominant. Also, 50 and 60 PPI foams have higher heat transfer limits than sintered copper powder. In the second part of this study, thermodynamic steady state modeling of a flat heat pipe has been done to study the effect of the different parameters on the dominant limit (capillary). A dimensionless number has been proposed to evaluate the balance between the pressure loss in the vapor and liquid phases as an additional design guideline to improve the capillary limit in flat heat pipes.

Modeling of Conduction and Natural Convection in Ice-Water Systems Containing Porous Metal Foams

2013 ◽  
Author(s):  
Sylvain Bories ◽  
B. Rabi Baliga
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Metal Foam ◽  
Porous Metal ◽  
Water Systems ◽  
Metal Foams ◽  
Local Thermal Equilibrium ◽  
Numerical Predictions ◽  
Laminar Natural Convection ◽  
Ice Water

Mathematical models and numerical predictions of heat conduction and laminar natural convection in ice-water systems containing porous metal foams are presented, in the context of computationally convenient two-dimensional steady-state problems with rectangular calculation domains. The Darcy-Brinkman-Forchheimer equations were used to model momentum transfer in the liquid-water-metal-foam region. For modeling the heat transfer, volume-averaged equations governing two intrinsic-phase-average temperature fields were used: one for the metal foam and the other for the water (solid or liquid). The following improvements are proposed: novel expressions for the interfacial (metal-water) heat transfer coefficient in both the convection and conduction regimes; and effective thermal conductivity correlations that provide consistency between the formulations of one-temperature and two-temperature models in the limit of local thermal equilibrium. A well-established fixed-grid, co-located, finite volume method (FVM) was adapted and used for the numerical solutions. The proposed models and FVM were used to solve the test and demonstration problems involving conduction and laminar natural convection in ice-water-aluminum-foam systems contained in rectangular enclosures. The findings and results of these investigations are presented and discussed in this paper.

Interstitial Heat Transfer Coefficient and Dispersion Conductivity in Compressed Metal Foam Heat Sinks

2006 ◽  
Vol 129 (2) ◽  
pp. 113-119 ◽  
Author(s):  
Sheng-Chung Tzeng ◽  
Tzer-Ming Jeng
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Metal Foam ◽  
Rectangular Channel ◽  
Metal Foams ◽  
High Porosity ◽  
Fluid Medium ◽  
Numerical Predictions

This work experimentally and numerically investigates the heat transfer in uncompressed∕compressed metal foams. Experiments were conducted to obtain the thermal characteristics of a rectangular channel filled with aluminum foams using air as the fluid medium. The experimental data reveal that the uncompressed sample has a larger Nusselt number (Nu) than the compressed sample. The 0.93 porosity sample has the largest average Nu followed by the 0.7 porosity sample; the 0.8 porosity sample has the worst average Nu. The experimental data concerning the 0.93 porosity samples (uncompressed samples) were consistent with the numerical predictions obtained using the model for high-porosity metal foam, reported elsewhere. Finally, a numerical model to simulate flow and heat transfer characteristics in compressed metal foams is presented and the interstitial heat transfer coefficient and dispersion conductivity were semi-empirically determined.

Assessment of heat transfer and pressure drop of metal foam-pin-fin heat sink

2021 ◽  
Vol 170 ◽  
pp. 107109
Author(s):  
Mohanad A. Alfellag ◽  
Hamdi E. Ahmed ◽  
Mohammed Gh. Jehad ◽  
Marwan Hameed
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Sink ◽  
Metal Foam ◽  
Pin Fin
Sign in / Sign up

Export Citation Format

Share Document