On the effective thermal conductivity of metal foams

Ranut, Paola

doi:10.1088/1742-6596/547/1/012021

Cited by 17 publications

(11 citation statements)

References 26 publications

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“…Optical Bragg mirrors are made of alternate layers of high and low dielectric function materials. To extend the definition to thermal waves we consider three specific materials: Aluminum 32 (Al) and two materials with thermal properties of biological tissue 16,24,33 . From the experimental point of view, materials with biological-like responses can be design with specific thermal properties using gel-phantoms 34 .…”

Section: Thermal Bragg Mirrorsmentioning

confidence: 99%

Thermal Bragg Shields for Thermal Waves.

Rosa¹,

Becerril²,

Gómez-Farfán³

et al. 2021

Preprint

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Ultrafast heating processes do not follow Fourier's heat conduction law, but rather the proposed Cattaneo-Vernotte equation (CVe) which has wave-like solutions that have some important differences from other wave phenomenon. In a periodic system made of materials with different thermal conductivities, solutions of the CVe lead to a band-like structure in the dispersion relation. In this work, we show that highly reflective Bragg mirrors for thermal waves can be designed. Even for a mirrors with a few layers a very high reflectance is achieved (>90%). The mirrors are made of materials with large thermal response times, where thermal waves have been measured. A second alternative consists of adding a thin metallic film which also leads to an efficient thermal Bragg mirror. Finally, the role of defects in opening new thermal-stop bands is demonstrated.

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Section: Thermal Bragg Mirrorsmentioning

confidence: 99%

Thermal Bragg Shields for Thermal Waves.

Rosa¹,

Becerril²,

Gómez-Farfán³

et al. 2021

Preprint

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“…This can support the development of more accurate generic correlations [10,12,18], but is limited by the small volumes of foams that can be investigated in this way. A review of the wide range of theoretical and empirical approaches for porous metals found that each model defines a specific morphology and is hence of limited applicability to other types [11,12,18]. This is discussed in more detail later in this work.…”

Section: Introductionmentioning

confidence: 96%

“…its porosity and pore size. A further problem with these materials is that the repeatability of the morphology is not constant, even when the same manufacturing conditions are employed, resulting in an inherent scatter in the material properties unless very large samples are tested [5,11,12].…”

Section: Introductionmentioning

confidence: 99%

The effective thermal conductivity of open cell replicated aluminium metal sponges

Abuserwal

Luna

Goodall

et al. 2017

International Journal of Heat and Mass Transfer

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“…In recent decades, mathematical models to investigate the heat transfer behavior of closed-cell foams have been solved numerically through different discrete element methods, such as finite element method (FEM), and finite volume method (FVM). A literature review of traditional and advanced techniques to predict the thermal conductivity of foamed materials showed that numerical analysis is an accurate approach to this end [ 7 , 8 , 9 ]. In the numerical analysis of thermal transport, the foam structure can be considered as a simple model that features a regular array of circles to produce closed-cell foam structures.…”

Section: Introductionmentioning

confidence: 99%

Numerical Study Using Microstructure Based Finite Element Modeling of the Onset of Convective Heat Transfer in Closed-Cell Polymeric Foam

et al. 2021

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The thermal performance of closed-cell foams as an insulation device depends on the thermal conductivity. In these systems, the heat transfer mode associated with the convective contribution is generally ignored, and studies are based on the thermo-physical properties that emerge from the conductive contribution, while others include a term for radiative transport. The criterion found in the literature for disregarding convective heat flux is the cell diameter; however, the cell size for which convection is effectively suppressed has not been clearly disclosed, and it is variously quoted in the range 3–10 mm. In practice, changes in thermal conductivity are also attributed to the convection heat transfer mode; hence, natural convection in porous materials is worthy of research. This work extends the field of study of conjugate heat transfer (convection and conduction) in cellular materials using microstructure-based finite element analysis. For air-based insulating materials, the criteria to consider natural convection (Ra=103) is met by cavities with sizes of 9.06 mm; however, convection is developed into several cavities despite their sizes being lower than 9.06 mm, hence, the average pore size that can effectively suppress the convective heat transfer is 6.0 mm. The amount of heat transported by convection is about 20% of the heat transported by conduction within the foam in a Ra=103, which, in turn, produces an increasing average of the conductivity of about 4.5%, with respect to a constant value.

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On the effective thermal conductivity of metal foams

Cited by 17 publications

References 26 publications

Thermal Bragg Shields for Thermal Waves.

Thermal Bragg Shields for Thermal Waves.

The effective thermal conductivity of open cell replicated aluminium metal sponges

Numerical Study Using Microstructure Based Finite Element Modeling of the Onset of Convective Heat Transfer in Closed-Cell Polymeric Foam

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