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Nihad Dukhan - One of the best experts on this subject based on the ideXlab platform.

  • influence of pore density on thermal development in open cell metal foam
    Experimental Thermal and Fluid Science, 2017
    Co-Authors: A Arbak, Özer Bağci, Nihad Dukhan, Mustafa Özdemir
    Abstract:

    Abstract Herein heat transfer measurements due to water flow in commercial open-cell aluminum foam confined by a cylindrical shell, which was heated by a constant heat flux, are described. Two kinds of commercial foam were tested: 10 and 40 Pores Per Inch (ppi). Measurements included wall temPerature along flow direction as well as average inlet and outlet temPeratures of water. Flow rates ranged from Darcy to Forchheimer regimes. The wall temPerature along the foam, as well as the local Nusselt number lucidly displayed thermal entry effects leading to thermal fully-developed conditions. The thermal entry length was about 2.9 pipe diameters (150 mm) for 10-ppi and 2.4 pipe diameters (122 mm) for 40-ppi foam; these were same for Darcy and Forchheimer flow regimes. It can be stated that the thermal entry length in open-cell metal foam was found to be significant and different from its porous-media analytically-predicted values and behavior. Moreover, the thermal entry length in metal foam was found to inversely proportional to the Pores density but in a weak manner.

  • exPerimental hydrodynamics of high porosity metal foam effect of pore density
    International Journal of Heat and Mass Transfer, 2016
    Co-Authors: Özer Bağci, Nihad Dukhan
    Abstract:

    Abstract Commercial open-cell metal foam has very high porosity (often greater than 90%) and a large surface area density. The open flow area is copious compared to the ligament size. These proPerties are exploited in many applications, e.g., heat exchanger, reactors and filters. Pressure drop, flow regimes, and transition from one to another, are indispensable for any application involving flow of a fluid through the foam, and for heat transfer rates or reaction paces. These topics are not well-agreed on for foam-like porous media such as metal, graphite and polymeric foams. Pressure drop parameters such as Permeability and form/inertial drag coefficients are very divergent for metal foam; the same can be said about flow regime boundaries. This paPer presents exPerimental data for pressure drop for water flow in two commercial open-cell aluminium foams having 10 and 40 Pores Per Inch (ppi). The two foams have similar porosities (88.5%). The wide range of flow Reynolds number covered all known flow regimes in porous media: pre-Darcy, Darcy, Forchheimer and turbulent. Flow regimes and transition between them were identified and compared. The friction factor based on the square root of Permeability (measured in the Darcy regime) and the Reynolds number based on the same characteristic length were used. It is shown that the same foam exhibits different values of its Permeability and Forchheimer coefficient in different flow regimes. A previously-tested foam having 20 Pores Per Inch and a porosity of 87.6% was included in the comparisons. The basic finding of this study will inform numerical and analytical work concerning flow and heat transfer in foam-like highly-porous porous media.

  • characterization of aluminum foam polypropylene interpenetrating phase composites flexural test results
    Mechanics of Materials, 2010
    Co-Authors: Nihad Dukhan, Nassif Rayess, James R Hadley
    Abstract:

    A type of interpenetrating phase composites was formed by impregnating 90%-porous open-cell aluminum foam with polypropylene through an injection molding process. Three aluminum foams were used having three distinct linear pore densities: 10, 20 and 40 Pores Per Inch (ppi) or roughly 4, 8 and 16 Pores Per cm. Samples taken from these composites were tested for flexural strength and stiffness based on ASTM D790-03. Flexural modulus and strength of the composite are compared to those of unreinforced polypropylene. The results showed, in general, the combination of the polymer and metal foams to be stiffer than either of the two individual components. The stiffness of the composites was found to increase with decreasing pore size. The smaller pore size allowed more cells to exist across the thickness of the specimen, and thus increased the bending stiffness of the composite.

  • one dimensional heat transfer analysis in open cell 10 ppi metal foam
    International Journal of Heat and Mass Transfer, 2005
    Co-Authors: Nihad Dukhan, Pablo D Quinonesramos, Edmundo Cruzruiz, Miguel Velezreyes, Elaine P Scott
    Abstract:

    A one-dimensional heat transfer model for open-cell metal foam is presented. The model combines the conduction in the ligaments and the convection to the coolant in the Pores. The approach avoids a complete three-dimensional modeling of the complex flow and heat transfer inside the foam. The temPerature along the foam decayed exponentially with the distance from the heated base. The model and the one-dimensional assumption were verified by direct exPeriment on a thin aluminum foam sample of ten Pores Per Inch for a range of pore Reynolds number. Good agreement was found between the analytical and the exPerimental results.

  • Simulations of Metal Foam Cooling of High-Power Electronics Using the Equivalent Thermal Conductivity
    Heat Transfer Volume 1, 2003
    Co-Authors: Nihad Dukhan, Pable D. Quinones
    Abstract:

    A one-dimensional heat transfer model for open-cell metal foam is presented. The model includes both the conduction and the convection in the ligaments and in the Pores of the foam. It uses the typical foam parameters provided by the manufacturers. Three aluminum foams having different relative surface areas, relative densities, ligament diameters, and number of Pores Per Inch are analyzed and an effective thermal conductivity is determined. The heat transfer increases with the number of Pores Per Inch. The resulting improvement in heat transfer can be as high as 57 Percent over solid aluminum. The model is general enough such that it can handle other types of foam and geometries. For simulations using packages for thermal management, the foam can be modeled as a solid having an equivalent conductivity with an effective convection heat transfer on its outer surfaces. This eliminates the need to model the microscopic flow and heat transfer in and around the Pores. It also allows quick feasibility studies and comparisons of different arrangements using aluminum foams for thermal management systems of high-power electronics. A few such simulations are presented in this work. The simulations show a big promise for using the foam in place of the traditional heat sinks for cooling high-power electronics: they reduce the cooling system’s weight substantially and reduce the maximum temPerature significantly.Copyright © 2003 by ASME

Pable D. Quinones - One of the best experts on this subject based on the ideXlab platform.

  • Simulations of Metal Foam Cooling of High-Power Electronics Using the Equivalent Thermal Conductivity
    Heat Transfer Volume 1, 2003
    Co-Authors: Nihad Dukhan, Pable D. Quinones
    Abstract:

    A one-dimensional heat transfer model for open-cell metal foam is presented. The model includes both the conduction and the convection in the ligaments and in the Pores of the foam. It uses the typical foam parameters provided by the manufacturers. Three aluminum foams having different relative surface areas, relative densities, ligament diameters, and number of Pores Per Inch are analyzed and an effective thermal conductivity is determined. The heat transfer increases with the number of Pores Per Inch. The resulting improvement in heat transfer can be as high as 57 Percent over solid aluminum. The model is general enough such that it can handle other types of foam and geometries. For simulations using packages for thermal management, the foam can be modeled as a solid having an equivalent conductivity with an effective convection heat transfer on its outer surfaces. This eliminates the need to model the microscopic flow and heat transfer in and around the Pores. It also allows quick feasibility studies and comparisons of different arrangements using aluminum foams for thermal management systems of high-power electronics. A few such simulations are presented in this work. The simulations show a big promise for using the foam in place of the traditional heat sinks for cooling high-power electronics: they reduce the cooling system’s weight substantially and reduce the maximum temPerature significantly.Copyright © 2003 by ASME

  • convective heat transfer analysis of open cell metal foam for solar air heaters
    Solar Energy, 2003
    Co-Authors: Nihad Dukhan, Pable D. Quinones
    Abstract:

    A one-dimensional heat transfer model for open-cell metal foam is presented. Three aluminum foams having different areas, relative densities, ligament diameters, and number of Pores Per Inch were analyzed. The effective thermal conductivity and the heat transfer increased with the number of Pores Per Inch. The effective thermal conductivity of the foams can be up to four times higher than that of solid aluminum. The resulting improvement in heat transfer can be as high as 50 Percent. The maximum heat transfer for the aluminum foams occurs at a pore Reynolds number of 52. The heat transfer, in addition, becomes insensitive to the flow regime for pore Reynolds numbers beyond 200.Copyright © 2003 by ASME

Özer Bağci - One of the best experts on this subject based on the ideXlab platform.

  • influence of pore density on thermal development in open cell metal foam
    Experimental Thermal and Fluid Science, 2017
    Co-Authors: A Arbak, Özer Bağci, Nihad Dukhan, Mustafa Özdemir
    Abstract:

    Abstract Herein heat transfer measurements due to water flow in commercial open-cell aluminum foam confined by a cylindrical shell, which was heated by a constant heat flux, are described. Two kinds of commercial foam were tested: 10 and 40 Pores Per Inch (ppi). Measurements included wall temPerature along flow direction as well as average inlet and outlet temPeratures of water. Flow rates ranged from Darcy to Forchheimer regimes. The wall temPerature along the foam, as well as the local Nusselt number lucidly displayed thermal entry effects leading to thermal fully-developed conditions. The thermal entry length was about 2.9 pipe diameters (150 mm) for 10-ppi and 2.4 pipe diameters (122 mm) for 40-ppi foam; these were same for Darcy and Forchheimer flow regimes. It can be stated that the thermal entry length in open-cell metal foam was found to be significant and different from its porous-media analytically-predicted values and behavior. Moreover, the thermal entry length in metal foam was found to inversely proportional to the Pores density but in a weak manner.

  • exPerimental hydrodynamics of high porosity metal foam effect of pore density
    International Journal of Heat and Mass Transfer, 2016
    Co-Authors: Özer Bağci, Nihad Dukhan
    Abstract:

    Abstract Commercial open-cell metal foam has very high porosity (often greater than 90%) and a large surface area density. The open flow area is copious compared to the ligament size. These proPerties are exploited in many applications, e.g., heat exchanger, reactors and filters. Pressure drop, flow regimes, and transition from one to another, are indispensable for any application involving flow of a fluid through the foam, and for heat transfer rates or reaction paces. These topics are not well-agreed on for foam-like porous media such as metal, graphite and polymeric foams. Pressure drop parameters such as Permeability and form/inertial drag coefficients are very divergent for metal foam; the same can be said about flow regime boundaries. This paPer presents exPerimental data for pressure drop for water flow in two commercial open-cell aluminium foams having 10 and 40 Pores Per Inch (ppi). The two foams have similar porosities (88.5%). The wide range of flow Reynolds number covered all known flow regimes in porous media: pre-Darcy, Darcy, Forchheimer and turbulent. Flow regimes and transition between them were identified and compared. The friction factor based on the square root of Permeability (measured in the Darcy regime) and the Reynolds number based on the same characteristic length were used. It is shown that the same foam exhibits different values of its Permeability and Forchheimer coefficient in different flow regimes. A previously-tested foam having 20 Pores Per Inch and a porosity of 87.6% was included in the comparisons. The basic finding of this study will inform numerical and analytical work concerning flow and heat transfer in foam-like highly-porous porous media.

Mancin Simone - One of the best experts on this subject based on the ideXlab platform.

  • Water pool boiling across low pore density aluminum foams
    'Informa UK Limited', 2019
    Co-Authors: Righetti Giulia, Doretti Luca, Sadafi Hosein, Hooman Kamel, Mancin Simone
    Abstract:

    In this paPer, exPerimental data Pertinent to deionized water pool boiling across 10 mm thick aluminum foams are presented. Two foam samples with different pore densities, 5 and 10 Pores Per Inch, yet an identical mean porosity of 0.92 are tested. Compared to a heated flat plate, of the same base size, the foams offer higher heat transfer area albeit at induced bubble escaping resistance. The tradeoff between these two effects is investigated. Through the use of high-speed camera recording, bubble generation, trajectory and growth rate were analyzed and critically discussed as functions of the working conditions and of the foam geometry. Furthermore, the exPerimental data were compared against a correlation appositely proposed for water pool boiling on metal foams. A good degree of agreement was observed

  • Hybrid PCM—aluminium foams’ thermal storages: an exPerimental study
    'Oxford University Press (OUP)', 2018
    Co-Authors: Lazzarin, Renato M, Mancin Simone, Noro Marco, Righetti Giulia
    Abstract:

    The latent heat absorption phenomenon associated with melting of a suitable Phase Change Material can be an effective way to improve the Thermal Energy Storage behaviour in many applications. However, the most suitable materials to be used in heating and refrigeration systems find intrinsic limitations due to their poor heat transfer capabilities. This work exPerimentally studies the use of aluminum foams as heat transfer medium to improve the overall heat transfer of paraffin waxes that can be possible phase change materials to be implemented in hybrid sensible-latent water thermal energy storages. The exPerimental tests were run in a dedicated setup designed, developed, and built at the Department of Management and Engineering of the University of Padova. The effects of the use of aluminum foams as enhancing heat transfer medium were studied by comparing the loading and unloading processes of a paraffin wax with melting temPerature around 40 \ub0C, with and without metal foams, in a water thermal storage unit. The effects of three different foams with 5, 20, and 40 Pores Per Inch (PPI) were investigated

  • Enhancement of Hybrid PCM Thermal Storages Using Aluminum foams
    2017
    Co-Authors: Lazzarin Renato, Mancin Simone, Noro Marco, Righetti Giulia
    Abstract:

    The latent heat absorption phenomenon associated with melting of a suitable Phase Change Material (PCM) can be an effective way to improve the Thermal Energy Storage (TES) behaviour in many applications. However, the most suitable PCMs to be used in HVAC and refrigeration systems find intrinsic limitations due to their poor heat transfer capabilities. This work exPerimentally studies the use of aluminum foams as heat transfer medium to improve the overall heat transfer of paraffin waxes that can be possible PCMs to be implemented in hybrid sensible-latent water TESs. The exPerimental tests were run in a new dedicated setup designed, developed, and built at the Department of Management and Engineering of the University of Padova to study the water hybrid TES. The exPerimental results are presented in terms of loading and unloading times at constant water tank temPerature. The effects of the use of aluminum foams as enhancing heat transfer medium were studied by comparing the loading and unloading processes of a paraffin wax with melting temPerature around 40 \ub0C, with and without metal foams, in a water thermal storage unit. The effects of three different foams with 5, 20, and 40 Pores Per Inch (PPI) were investigated

  • Material and height effects on the heat transfer Performance of metal foams cooled by air in forced convection
    'AIP Publishing', 2012
    Co-Authors: Mancin Simone, Zilio Claudio, Diani Andrea, Rossetto Luisa
    Abstract:

    In this paPer, copPer and aluminum foams with different porosity, number of Pores Per Inch (PPI) and foam core height, are exPerimentally studied during air forced convection. The exPerimental measurements Permit to understand how each parameter (i.e. porosity, PPI, material, and foam thickness) affects the heat transfer and fluid flow behavior of the metal foams. The paPer presents the exPerimental heat transfer coefficients, Permeability and inertia coefficients; moreover, it reports the normalized mean wall temPerature as a function of the pumping power Per unit of heat transfer area: two meaningful parameters that allow quantitative comparisons of different enhanced surfaces, which can be considered suitable for electronic thermal management

  • Aluminum foams as possible extended surfaces for air cooled condenser
    place:PARIS, 2011
    Co-Authors: Zilio Claudio, Mancin Simone, Diani Andrea, Rossetto Luisa
    Abstract:

    Metal foams are a class of cellular structured materials with low density and novel thermal and mechanical proPerties. Open cell metal foams have high specific surface area, relative high thermal conductivity and present tortuous flow path to promote mixing. Recently, aluminum foams have been suggested as a highly compact replacement for conventional fins for brazed aluminum heat exchangers. This paPer presents a study on possible application of aluminum foams in compact air cooled condensers to be inserted in a mini vapour cycle system (VCS) for electronics cooling in aeronautical application. Present authors have exPerimentally measured the heat transfer coefficients and pressure drops during air forced convection in several aluminum foams with different pore densities and porosities. The effects of the pore density on the heat transfer and fluid flow Performance of the aluminium foams are highlighted by varying the number of Pores Per Inch from 5 to 40. Starting from the exPerimental campaigns, the Performance of air cooled condensers, especially designed for aeronautical applications which implement these new enhanced surfaces, are simulated using a numerical code. Finally, the simulated solutions with aluminum foams are compared with a reference air cooled condenser with traditional finned surface

Rossetto Luisa - One of the best experts on this subject based on the ideXlab platform.

  • Numerical investigation of pressure drop and heat transfer through reconstructed metal foams and comparison against exPeriments
    'Elsevier BV', 2015
    Co-Authors: Diani Andrea, Rossetto Luisa, Bodla, Karthik K., Garimella Suresh
    Abstract:

    Direct numerical simulation of transport in foam materials can benefit from realistic representations of the porous-medium geometry generated by employing non-destructive 3D imaging techniques. X-ray microtomography employs computer-processed X-rays to produce tomographic images or slices of specific regions of the object under investigation, and is ideally suited for imaging opaque and intricate porous media. In this work, we employ micro-CT for numerical analysis of air flow and convection through four different high-porosity copPer foams. All four foam samples exhibit approximately the same relative density (6.4-6.6% solid volume fraction), but have different pore densities (5, 10, 20, and 40 Pores Per Inch, PPI). A commercial micro-computed tomography scanner is employed for scanning the 3D microstructure of the foams at a resolution of 20 \u3bcm, yielding stacks of two-dimensional images. These images are processed in order to reconstruct and mesh the real, random structure of the foams, upon which simulations are conducted of forced convection through the pore spaces of the foam samples. The pressure drop values from this \u3bcCT based CFD analysis are compared against prior exPerimental results; the computational interfacial heat transfer results are compared against the values predicted by an empirical correlation previously reported, revealing excellent agreement between the numerical and exPerimental/empirical hydraulic and thermal results, thus highlighting the efficacy of this novel approach

  • Numerical Analysis of Air Flow through Metal Foams
    The Authors. Published by Elsevier Ltd., 2014
    Co-Authors: Diani Andrea, Rossetto Luisa, Bodla, Kartik K., Garimella Suresh
    Abstract:

    AbstractX-ray micro computed tomography (μ-CT), originally developed for non-destructive biomedical imaging, is increasingly being employed in areas as diverse as materials characterization and reverse engineering. The technique employs computer processed X-rays to produce tomographic images or slices of specific regions of the object under investigation.This paPer presents a numerical analysis of air flow through four different high-porosity ERG copPer foams having different pore sizes (5, 10, 20, and 40 Pores Per Inch, PPI), and approximately the same relative density (6.4-6.6% solid fraction). These samples were scanned with a commercial micro computed tomography scanner at a resolution of 20μm, yielding a stack of two- dimensional images. Starting with these two-dimensional images, the real, random structure of the foams was reconstructed and subsequently meshed using the commercial software Simpleware. Meshes thus produced were then exported to FLUENT for simulating the fluid flow through the pore space of the foam samples. The results of μ-CT based CFD computations are compared against exPerimental measurements of pressure drop that were previously obtained with the same samples. The comparison reveals excellent agreement between the numerical and exPerimental results, highlighting the accuracy of this novel approach

  • Material and height effects on the heat transfer Performance of metal foams cooled by air in forced convection
    'AIP Publishing', 2012
    Co-Authors: Mancin Simone, Zilio Claudio, Diani Andrea, Rossetto Luisa
    Abstract:

    In this paPer, copPer and aluminum foams with different porosity, number of Pores Per Inch (PPI) and foam core height, are exPerimentally studied during air forced convection. The exPerimental measurements Permit to understand how each parameter (i.e. porosity, PPI, material, and foam thickness) affects the heat transfer and fluid flow behavior of the metal foams. The paPer presents the exPerimental heat transfer coefficients, Permeability and inertia coefficients; moreover, it reports the normalized mean wall temPerature as a function of the pumping power Per unit of heat transfer area: two meaningful parameters that allow quantitative comparisons of different enhanced surfaces, which can be considered suitable for electronic thermal management

  • Aluminum foams as possible extended surfaces for air cooled condenser
    place:PARIS, 2011
    Co-Authors: Zilio Claudio, Mancin Simone, Diani Andrea, Rossetto Luisa
    Abstract:

    Metal foams are a class of cellular structured materials with low density and novel thermal and mechanical proPerties. Open cell metal foams have high specific surface area, relative high thermal conductivity and present tortuous flow path to promote mixing. Recently, aluminum foams have been suggested as a highly compact replacement for conventional fins for brazed aluminum heat exchangers. This paPer presents a study on possible application of aluminum foams in compact air cooled condensers to be inserted in a mini vapour cycle system (VCS) for electronics cooling in aeronautical application. Present authors have exPerimentally measured the heat transfer coefficients and pressure drops during air forced convection in several aluminum foams with different pore densities and porosities. The effects of the pore density on the heat transfer and fluid flow Performance of the aluminium foams are highlighted by varying the number of Pores Per Inch from 5 to 40. Starting from the exPerimental campaigns, the Performance of air cooled condensers, especially designed for aeronautical applications which implement these new enhanced surfaces, are simulated using a numerical code. Finally, the simulated solutions with aluminum foams are compared with a reference air cooled condenser with traditional finned surface

  • Aluminum foams vs conventional extended surfaces for air cooled condensers
    Barcello Editore, 2011
    Co-Authors: Zilio Claudio, Mancin Simone, Diani Andrea, Rossetto Luisa
    Abstract:

    Metal foams are a class of cellular structured materials with low density and novel thermal and mechanical proPerties. Open cell metal foams have high specific surface area, relative high thermal conductivity and present tortuous flow path to promote mixing. Recently, aluminum foams have been suggested as a highly compact replacement for conventional fins for brazed aluminum heat exchangers. This paPer presents a study on possible application of aluminum foams in compact air cooled condensers to be inserted in a mini vapour cycle system (VCS) for electronics cooling in aeronautical application. Present authors have exPerimentally measured the heat transfer coefficients and pressure drops during air forced convection in several aluminum foams with different pore densities and porosities. The effects of the pore density on the heat transfer and fluid flow Performance of the aluminium foams are highlighted by varying the number of Pores Per Inch from 5 to 40. Starting from the exPerimental campaigns, the Performance of air cooled condensers, especially designed for aeronautical applications which implement these new enhanced surfaces, are simulated using a numerical code. Finally, the simulated solutions with aluminum foams are compared with a reference air cooled condenser with traditional finned surface