scholarly journals Numerical study of pore-scale flow and noise of an open cell metal foam

2018 ◽  
Vol 82-83 ◽  
pp. 185-198 ◽  
Author(s):  
Chen Xu ◽  
Yijun Mao ◽  
Zhiwei Hu
Keyword(s):  
Metal Foam ◽  
Numerical Study ◽  
Pore Scale ◽  
Open Cell

Numerical Study of Heat Conduction of High Porosity Open-Cell Metal Foam/Paraffin Composite at Pore Scale

2016 ◽  
Author(s):  
Yuanpeng Yao ◽  
Huiying Wu ◽  
Zhenyu Liu
Keyword(s):  
Heat Transfer ◽  
Heat Conduction ◽  
Pore Size ◽  
Metal Foam ◽  
Foam Cell ◽  
High Porosity ◽  
Pore Scale ◽  
Thermal Equilibrium State ◽  
Foam Structure ◽  
Open Cell

In this paper, a numerical model employing 3D foam structure represented by Weaire-Phelan foam cell is developed to study the steady heat conduction of high porosity open-cell metal foam/paraffin composite at the pore-scale level. Two conduction problems are considered in the cubic representative computation unit of the composite material: one with constant temperature difference between opposite sides of the cubic unit (that can be used to determine the effective thermal conductivity (ETC)) and the second with constant heat flux at the interface between metal foam and paraffin (that can be used to determine the interstitial conduction heat transfer coefficient (ICHTC)). The effects of foam pore structure parameters (pore size and porosity) on heat conduction are investigated for the above two problems. Results show that for the first conduction problem, the effect of foam structure on heat conduction (i.e. the ETC) is related to porosity rather than pore size. The essential reason is due to the thermal equilibrium state between metal foam and paraffin indicated by the negligible interstitial heat transfer. While for the second conduction problem with inherent thermal non-equilibrium effect, it shows that both porosity and pore size significantly influence the interstitial heat conduction (i.e. the ICHTC). Furthermore, the present ETC and ICHTC data are compared to the results in the published literature. It shows that our ETC data agree well with the reported experimental results, and are more accurate than the numerical predications based on body-centered-cubic foam cell in literature. And our ICHTC data are in qualitative agreement with the published numerical results, but the present results are based on a more realistic foam structure.

Pore Scale Investigation of Heat Conduction of High Porosity Open-Cell Metal Foam/Paraffin Composite

2017 ◽  
Vol 139 (9) ◽  
Author(s):  
Yuanpeng Yao ◽  
Huiying Wu ◽  
Zhenyu Liu
Keyword(s):  
Heat Conduction ◽  
Pore Size ◽  
Metal Foam ◽  
Volume Fraction ◽  
Experimental Studies ◽  
Scale Model ◽  
Small Scale ◽  
High Porosity ◽  
Pore Scale ◽  
Open Cell

In this paper, a numerical model employing an approximately realistic three-dimensional (3D) foam structure represented by Weaire–Phelan foam cell is developed to study the steady-state heat conduction of high porosity open-cell metal foam/paraffin composite at the pore-scale level. The conduction problem is considered in a cubic representative computation unit of the composite material with a constant temperature difference between one opposite sides of the cubic unit (the other outer surfaces of the cubic unit are thermally insulated). The effective thermal conductivities (ETCs) of metal foam/paraffin composites are calculated with the developed pore-scale model considering small-scale details of heat conduction, which avoids using adjustable free parameters that are usually adopted in the previous analytical models. Then, the reason why the foam pore size has no evident effect on ETC as reported in the previous macroscopic experimental studies is explored at pore scale. Finally, the effect of air cavities existing within solid paraffin in foam pore region on conduction capacity of metal foam/paraffin composite is investigated. It is found that our ETC data agree well with the reported experimental results, and thus by direct numerical simulation (DNS), the ETC data of different metal foam/paraffin composites are provided for engineering applications. The essential reason why pore size has no evident effect on ETC is due to the negligible interstitial heat transfer between metal foam and paraffin under the present thermal boundary conditions usually used to determine the ETC. It also shows that overlarge volume fraction of air cavity significantly weakens the conduction capacity of paraffin, which however can be overcome by the adoption of high conductive metal foam due to enhancement of conduction.

Dispersion in Metal Foam: A Pore Scale Numerical Study

2012 ◽  
Vol 326-328 ◽  
pp. 410-415
Author(s):  
Jean Michel Hugo ◽  
Frédéric Topin
Keyword(s):  
Metal Foam ◽  
Numerical Study ◽  
Fluid Phase ◽  
Numerical Approach ◽  
Representative Elementary Volume ◽  
Pore Scale ◽  
Elementary Volume ◽  
Foam Sample ◽  
Mass Fluxes ◽  
Phase Conductivity

We determine thermal dispersion in metal foams using a pore scale numerical approach. Samples are contained in a channel crossed by a steady fully established fluid flow. The size of the foam sample is chosen according to a Representative Elementary Volume (REV).Two configurations are tested with several foam structures, pore size and pore shape. In the first configuration, heat and mass fluxes are in the same direction, in the second one, fluxes are perpendicular such as in heat exchanger. Results obtained on apparent fluid phase conductivity are discussed along with pressure drop data and compared to available literature data.

Local Thermal Nonequilibrium During Melting of a Paraffin Filled in an Open-Cell Copper Foam: A Visualized Study at the Pore-Scale

2016 ◽  
Vol 139 (3) ◽  
Author(s):  
Li-Wu Fan ◽  
Hong-Qing Jin
Keyword(s):  
Thermal Imaging ◽  
Metal Foam ◽  
Pore Scale ◽  
Thermal Nonequilibrium ◽  
Rectangular Cell ◽  
Open Cell ◽  
Copper Foam ◽  
Imaging Results ◽  
Local Thermal Nonequilibrium ◽  
Visualized Study

In this technical brief, the application of infrared thermal imaging to investigate melting of a phase-change material (PCM) filled in an open-cell metal foam was proposed. Melting experiments in a rectangular cell were performed with paraffin/copper foam composite samples having a single pore size of 15 ppi. The visualized study at the pore-scale was enabled using an infrared video camera equipped with a macrolens, offering a resolution of 50 μm. The transient thermal imaging results were first validated against the temperature readings by a pre-installed thermocouple. A relative deviation below 4% was observed between the two methods over the entire course of melting. The local thermal nonequilibrium between a copper ligament and its surrounding paraffin was found to become more pronounced as melting proceeds, which could reach up to the order of 10 °C during the late stage of melting. The quantitative observation of the local thermal nonequilibrium effect may facilitate improvement of the existing two-temperature models for numerical simulations on melting of PCM enhanced by embedding metal foams.

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