Effect of Foam Properties on Heat Transfer in High Temperature Open‐Cell Foam Inserts

Abstract

Light weight materials such as foams can be used in thermal protection and/or thermal insulation systems. At high temperature (>1000 K), thermal radiation may be important or dominate heat transfer in the foam; however, studies based on more detailed thermal radiation analysis are limited. In this study, foams are considered to be semitransparent, because radiation can penetrate through the pore (or void) space and/or foam skeleton (solid matrix), depending on the materials from which the foams are made. Of particular interest in this study is to understand how the properties such as foam material, porosity, pore size, etc. affect thermal and radiant energy transfer. Physical and mathematical models are developed to account for conduction and radiation (absorption, emission and scattering) in the porous material. The spectral extinction coefficients of SiC foams are measured experimentally in the laboratory at room temperature, and the radiative transfer equation is solved using the spherical harmonics P1‐approximation. The predicted radiative heat fluxes in foams are compared with those based on the Rosseland diffusion approximation. Parametric calculations have been carried out, and the results are reported in the article for a range of parameters characterizing heat transfer in SiC foams of different porosities to identify desirable conditions for effectively reducing heat transfer in potential thermal protection concepts.

Numerical Analysis on the Radiation-Convection Coupled Heat Transfer in an Open-Cell Foam Filled Annulus

“…The P1 approximation was employed to simulate the radiation transport inside the porous foam, as it is an effective approach that is less time consuming and provides high accuracy [35,36]. For an isotropic scattering medium, the governing equation of the incident radiation, G, was expressed as [37]…”

Ablation resistance of precursor derived Si-Hf-C-N(O) ceramics

“…A detailed review on the optimal design of foams suggests that micro-architected cellular materials possess superior mechanical properties [5]. Recently, in SiC foams, it was shown that the pore and strut diameter affects the heat transfer (thermal radiation) [6]. The usage of these foams leads to reduction in weight of the structural components, thus increasing the fuel efficiency.…”

Composite of Coal‐Series Kaolinite and Capric–Lauric Acid as Form‐Stable Phase‐Change Material

“…[1][2][3][4] Thermal energy storage is an essential method to improve energy efficiency, and it can be used to solve contradictions of heat supply and demand in time and space. [5,6] Phase-change materials (PCMs) for thermal energy storage have received significant attention for their efficient use of thermal energy in recent years. [7][8][9][10] The main advantage of PCMs is that they are able to store heat energy in a latent form, which results in a greater heat storage capacity per unit volume than that of conventional building materials.…”