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Chin. Phys. B, 2024, Vol. 33(6): 064401    DOI: 10.1088/1674-1056/ad47ac
Special Issue: SPECIAL TOPIC — Heat conduction and its related interdisciplinary areas
SPECIAL TOPIC—Heat conduction and its related interdisciplinary areas Prev   Next  

Theoretical study on the effective thermal conductivity of silica aerogels based on a cross-aligned and cubic pore model

Kuncan Zheng(郑坤灿)1,2,†, Zhendong Li(李震东)1, Yutong Cao(曹豫通)1, Ben Liu(刘犇))1, and Junlei Hu(胡君磊)1
1 School of Energy and Environment, Inner Mongolia University of Science and Technology, Baotou 014010, China;
2 Inner Mongolia Key Laboratory of Efficient and Clean Combustion, Baotou 014010, China
Abstract  Aerogel nanoporous materials possess high porosity, high specific surface area, and extremely low density due to their unique nanoscale network structure. Moreover, their effective thermal conductivity is very low, making them a new type of lightweight and highly efficient nanoscale super-insulating material. However, prediction of their effective thermal conductivity is challenging due to their uneven pore size distribution. To investigate the internal heat transfer mechanism of aerogel nanoporous materials, this study constructed a cross-aligned and cubic pore model (CACPM) based on the actual pore arrangement of SiO$_{2}$ aerogel. Based on the established CACPM, the effective thermal conductivity expression for the aerogel was derived by simultaneously considering gas-phase heat conduction, solid-phase heat conduction, and radiative heat transfer. The derived expression was then compared with available experimental data and the Wei structure model. The results indicate that, according to the model established in this study for the derived thermal conductivity formula of silica aerogel, for powdery silica aerogel under the conditions of $T=298$K, $a_{2} =0.85$, $D_{1} =90μ $m, $\rho =128{\rm kg/m}^{3}$, within the pressure range of 0-10$^{5}$Pa, the average deviation between the calculated values and experimental values is 10.51%. In the pressure range of 10$^{3}$-10$^{4}$Pa, the deviation between calculated values and experimental values is within 4%. Under these conditions, the model has certain reference value in engineering verification. This study also makes a certain contribution to the research of aerogel thermal conductivity heat transfer models and calculation formulae.
Keywords:  silica aerogel      effective thermal conductivity      two pore-size structure model      porous medium heat transfer  
Received:  18 January 2024      Revised:  16 April 2024      Accepted manuscript online:  06 May 2024
PACS:  44.30.+v (Heat flow in porous media)  
  64.70.qd (Thermodynamics and statistical mechanics)  
  51.30.+i (Thermodynamic properties, equations of state)  
  61.43.-j (Disordered solids)  
Fund: This project is supported by the National Natural Science Foundation of China (Grant Nos. 51764046 and 52160013), the Inner Mongolia Autonomous Region Postgraduate Research Innovation Project of China (Grant No. S20231165Z),and the Research Program of Science and Technology at Universities of Inner Mongolia Autonomous Region of China (Grant Nos. 2023RCTD016 and 2024RCTD008).
Corresponding Authors:  Kuncan Zheng     E-mail:  zhengkunchan@hotmail.com

Cite this article: 

Kuncan Zheng(郑坤灿), Zhendong Li(李震东), Yutong Cao(曹豫通), Ben Liu(刘犇)), and Junlei Hu(胡君磊) Theoretical study on the effective thermal conductivity of silica aerogels based on a cross-aligned and cubic pore model 2024 Chin. Phys. B 33 064401

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