文献类型：期刊文献

英文题名：The correlation between multilevel micro-nano structures and thermal conductivity of nanoporous phenolic composites reinforced by needled fiber preforms

作者：Zhou, Xiaoyi[1];Niu, Bo[1,2];Pan, Helin[1];Zhang, Yayun[1,2];Long, Donghui[1,2]

机构：[1]East China Univ Sci & Technol, State Key Lab Chem Engn, Shanghai 200237, Peoples R China;[2]East China Univ Sci & Technol, Key Lab Specially Funct Mat & Related Technol, Shanghai 200237, Peoples R China

年份：2024

卷号：221

外文期刊名：INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER

收录：;EI(收录号：20235015192621);WOS:【SCI-EXPANDED(收录号:WOS:001134898600001)】；

基金：This work was supported by the National Natural Science Foundation of China (Nos. 22078100, 52102098 and 22008073) and China Post- doctoral Science Foundation (2022M711140) .

语种：英文

外文关键词：Nanoporous phenolic composites; Thermal conductivity; Lattice Boltzmann method; X-ray micro -CT

摘要：Nanoporous phenolic composites (NPC) are the most promising ablative thermal protection materials, but accurately modeling and effective thermal conductivity (lambda eff) prediction remains a significant challenge due to their intricate micro-nano structures. Herein, a modified generation method, which incorporates structural pa-rameters from micro-CT, is proposed to develop precise NPC structural models for assessing the correlation between micro-nano structures and lambda eff. The Lattice Boltzmann method and Fourier's law are employed to predict their lambda eff, with only 8% discrepancy from experiment. Results from phenolic matrix reveals that once the porosity of matrix exceeds 60%, any further increases have a limited effect on lambda eff due to the Knudsen effect at nanoscale. Additionally, fiber structure analysis indicates that an increase in yarn height or width results in a decrease in lambda eff, yet if product of the two is maintained, lambda eff remains unchanged as the yarn cross-sectional area remains constant. Furthermore, investigation into stacked preforms demonstrates that lambda eff increases linearly with the number of fabric layers at a constant felt density, but decreases at a constant preform density owing to densely packed yarns. These results reveal the correlation between multilevel micro-nano structures and thermal con-ductivity of NPC, providing important guidance for optimizing the NPC thermal insulation performance.