CUED Publications database

Natural convection in metal foams with open cells

Zhao, CY and Lu, TJ and Hodson, HP (2005) Natural convection in metal foams with open cells. International Journal of Heat and Mass Transfer, 48. pp. 2452-2463. ISSN 0017-9310

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Abstract

This paper presents a combined experimental and numerical study on natural convection in open-celled metal foams. The effective thermal conductivities of steel alloy (FeCrAlY) samples with different relative densities and cell sizes are measured with the guarded-hot-plate method. To examine the natural convection effect, the measurements are conducted under both vacuum and ambient conditions for a range of temperatures. The experimental results show that natural convection is very significant, accounting for up to 50% of the effective foam conductivity obtained at ambient pressure. This has been attributed to the high porosity (ε > 0.9) and inter-connected open cells of the metal foams studied. Morphological parameters characterizing open-celled FeCrAlY foams are subsequently identified and their cross-relationships are built. The non-equilibrium two-equation energy transfer model is employed, and selected calculations show that the non-equilibrium effect between the solid foam skeleton and air is significant. The study indicates that the combined parameter, i.e., the porous medium Rayleigh number, is no longer appropriate to correlate natural convection by itself when the Darcy number is sufficiently large as in the case of natural convection in open-celled metal foams. Good agreement between model predictions and experimental measurements is obtained. © 2005 Elsevier Ltd. All rights reserved.

Item Type: Article
Uncontrolled Keywords: Cellular metal foams Measurements Modeling Natural convection Thermal conductivity
Subjects: UNSPECIFIED
Divisions: Div A > Turbomachinery
Depositing User: Cron Job
Date Deposited: 07 Mar 2014 11:42
Last Modified: 08 Dec 2014 02:24
DOI: 10.1016/j.ijheatmasstransfer.2005.01.002