1 Copyright © 2009 by ASME Proceedings of HT2009 2009 ASME Summer Heat Transfer Conference July 19-23, 2009, San Francisco, California USA HT2009-88557 THERMAL CONDUCTIVITY AND THERMAL CONTACT RESISTANCE OF METAL FOAMS Ehsan Sadeghi Department of Mechanical Engineering University of Victoria ehsans@uvic.ca Nedjib Djilali Department of Mechanical Engineering University of Victoria ndjilai@uvic.ca Majid Bahrami School of Engineering Science Simon Fraser University mbahrami@sfu.ca ABSTRACT Unique specifications of metal foams such as relatively low cost, ultra-low density, high surface-area-to-volume ratio, and most importantly, the ability to mix the passing fluid provide them a great potential for a variety of thermal-fluidics applications. In the present study, a compact analytical model for evaluating the effective thermal conductivity of metal foams is developed. The medium structure is represented as orthogonal cylindrical ligaments that are equally spaced and sized. A unit cell is taken to represent the metal foam. The model accounts for varying cross-sectional ligaments which is consistent with microscopic images. A numerical analysis is performed to verify the proposed analytical models. The model predictions are in good agreement with existing experimental data and the present numerical results. A parametric study is then performed to investigate the effects of variation in ligament cross-section geometry, uniformity, and aspect ratio over a wide range of porosities. Moreover, Thermal contact resistance phenomenon is included in the analysis. NOMENCLATURE  = Unit cell size,   = Major semi-axis of the outer geometry of ligament cross-section, Fig. 4,    = Major semi-axis of the inner geometry of ligament cross-section, Fig. 4,   = Minor semi-axis of the outer geometry of ligament cross-section, Fig. 4,    = Minor semi-axis of the inner geometry of ligament cross-section, Fig. 4,    = Solid thermal conductivity, /.    = Fluid thermal conductivity, /.    = Effective thermal conductivity, /.   , = Effective thermal conductivity for the solid ligament structure, Eq. (28), /.   = Slope of linear variation in ligament cross- section  = Pore density  = Inner-to-outer void ratio for hollow ligament structures  = Thermal resistance, /   = Thermal constriction resistance, /   = Total thermal resistance of the unit cell, /   = Total thermal resistance of the medium, /  = Thermal contact resistance, / Greek symbols  = Ligament aspect ratio  = Porosity of solid ligament metal foams