The effective thermal conductivity of virtual macroporous structures

Abstract

Recent developments in macroporous structures featuring metallic bodies are becoming a focus of research due to their improved load-bearing capacity and high specific surface area, making them potential candidates for thermofluidic applications. Through numerical modelling and simulations at the pore-scale, this paper examines the ability of virtual macroporous structures generated by sphere-packing models to predict the effective thermal conductivity of “bottleneck-type” macroporous structures. Simulations of virtual macroporous structures with monosized pores show the relative impact of key pore structure-related properties on effective thermal conductivity in such structures. The extension of these findings to bimodal and adapted designs results in an increase in fluid transverse capacity of these structures, causing an increase in the original monomodal pore volume by 17 and 30% respectively, while varying their capillary radius from 10 to 80 μm only results in a 10% increase in pore volume fraction. Overall, this study demonstrated that pore structure-related properties played an important role in conductive heat transfer, with material porosity being an influential property and inversely (non- linear) correlated with the effective thermal conductivity of the foam–fluid system. The contributions tendered by material pores and specific surfaces were minimal, and mathematical relationships were proposed between effective thermal conductivity, pore-structure-related properties, and fluid and solid thermal conductivity values. Modelling techniques such as this one could serve to optimize the thermal performance of macroporous structures, as well as to gain the benefits of being ultra-lightweight and having a high Young modulus.