A review on heat transfer in nanoporous silica aerogel insulation materials and its modeling

Zhu, Chuanyong; Xu, Haibo; Zhao, Xinpeng; Gong, Liang; Li, Zeng-Yao

doi:10.1016/j.enss.2022.07.003

Cited by 16 publications

(9 citation statements)

References 130 publications

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“…In the past decades, signi cant progress has been made in understanding the heat transfer mechanisms in conventional silica aerogels and in developing structure-TC relationships [54,55]. Yet, such knowledge on ber-based exible aerogels remains limited.…”

Section: Structure-thermal Conductivity (Tc) Relationships and Therma...mentioning

confidence: 99%

“…Because the AZFA samples have similar ber arrangements and near isotropic macropore con gurations, the increase in TC is mainly ascribed to larger λ s , which is governed by (i) solid conductivity, an intrinsic property of solid material, related to the chemical composition and micro/nanostructure, and (ii) tortuosity, a description of the intricacy of solid phase heat transfer path [54,55]. In this case, the ber morphology and crystalline microstructures affect the solid conductivity by deciding the phonon scattering events that give rise to thermal resistance.…”

Section: Structure-thermal Conductivity (Tc) Relationships and Therma...mentioning

confidence: 99%

“…Both AZFA and AZFA-1000 are mesoporous, with pore size (D) of 5-30 nm and > 10 nm respectively, corresponding to K n < < 1. This indicates that although the total volume of the mesopores is neglectable compared to the > 99.9 vol% of macropores between bers, the mesopores can trap the gas molecules and signi cantly suppress the air conduction, i.e., λ g < λ g0 [54,65].…”

Section: Structure-thermal Conductivity (Tc) Relationships and Therma...mentioning

confidence: 99%

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3D Electrospinning of Al2O3/ZrO2 Fibrous Aerogels for Multipurpose Thermal Insulation

Dong

Maciejewska

Millar³

et al. 2023

Preprint

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Ceramic aerogels are excellent ultralight-weight thermal insulators yet impractical due to their tendency towards structural degradation at elevated temperatures, under mechanical disturbances, or in humid environments. Here, we present flexible and durable alumina/zirconia fibrous aerogels (AZFA) fabricated using 3D sol-gel electrospinning - a technique enabling in situ formation of 3D fiber assemblies with significantly reduced time consumption and low processing cost compared to most existing methods. Our AZFAs exhibit ultralow density (> 3.4 mg cm-3), low thermal conductivity (> 21.6 mW m-1 K-1), excellent fire resistance, whilst remaining mechanically elastic and flexible at 1300°C, and thermally stable at 1500°C. Particularly, we investigate the underlying structure-thermal conductivity relationships, demonstrating that the macroscopic fiber arrangement dictates the solid-phase thermal conduction, while mesopores in the fiber effectively trap air hence decreasing the gas conduction. We show experimentally and theoretically that directional heat transport, i.e., anisotropic thermal conductivity, can be achieved through compressing the fiber network. We further solve the moisture sensitivity problem of common fibrous aerogels through fluorination coating. The resulting material possesses excellent hydrophobicity and self-cleaning properties, which can provide reliable thermal insulation under various conditions, including but not limited to high-temperature conditions in vehicles and aircraft, wet humid conditions in buildings, and underwater environments for oil pipelines.

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Section: Structure-thermal Conductivity (Tc) Relationships and Therma...mentioning

confidence: 99%

Section: Structure-thermal Conductivity (Tc) Relationships and Therma...mentioning

confidence: 99%

Section: Structure-thermal Conductivity (Tc) Relationships and Therma...mentioning

confidence: 99%

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3D Electrospinning of Al2O3/ZrO2 Fibrous Aerogels for Multipurpose Thermal Insulation

Dong

Maciejewska

Millar³

et al. 2023

Preprint

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show abstract

“…In the past decades, significant progress has been made in understanding the heat transfer mechanisms in conventional silica aerogels and developing structure-TC relationships [53,54]. Yet, such knowledge of fiber-based flexible aerogels remains limited.…”

Section: Structure-thermal Conductivity (Tc) Relationships and Therma...mentioning

confidence: 99%

3D Electrospinning of Al2O3/ZrO2 fibrous aerogels for multipurpose thermal insulation

Dong,

Maciejewska,

Millar

et al. 2023

Adv Compos Hybrid Mater

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Ceramic aerogels are excellent ultralight-weight thermal insulators yet impractical due to their tendency towards structural degradation at elevated temperatures, under mechanical disturbances, or in humid environments. Here, we present flexible and durable alumina/zirconia fibrous aerogels (AZFA) fabricated using 3D sol–gel electrospinning — a technique enabling in situ formation of 3D fiber assemblies with significantly reduced time consumption and low processing cost compared to most existing methods. Our AZFAs exhibit ultralow density (> 3.4 mg cm−3), low thermal conductivity (> 21.6 mW m−1 K−1), excellent fire resistance, while remaining mechanically elastic and flexible at 1300 °C, and thermally stable at 1500 °C. We investigate the underlying structure-thermal conductivity relationships, demonstrating that the macroscopic fiber arrangement dictates the solid-phase thermal conduction, and the mesopores in the fiber effectively trap air thereby decreasing the gas conduction. We show experimentally and theoretically that directional heat transport, i.e., anisotropic thermal conductivity, can be achieved through compressing the fiber network. We further solve the moisture sensitivity problem of common fibrous aerogels through fluorination coating. The resulting material possesses excellent hydrophobicity and self-cleaning properties, which can provide reliable thermal insulation under various conditions, including but not limited to high-temperature conditions in vehicles and aircraft, humid conditions in buildings, and underwater environments for oil pipelines. Graphical Abstract

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“…Many research on manufacturing, modelling, life cycle assessment of thermal insulators and particularly nano insulators has been carried out in recent years [11][12][13][14][15][16][17][18]. Super-insulation is defined by a thermal conductivity lower than that of air, i.e., a thermal conductivity lower than λ = 0.025 W/(m.K).…”

Section: Introductionmentioning

confidence: 99%

Nano technology building insulation effect on the thermal behavior of building under different Algerian weather

2022

IJM

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The energy consumption of the building sector in Algeria represents the largest part of the energy produced in the country. Action to reduce the impact of this sector on the economy and the environment must be taken. The use of thermal insulation to reduce the energy needs of the building sector represents an effective and sustainable solution.The objective of our work is to conduct a study using the TRNSYS 17 software on the influence of the use of thermal insulation in different climates in Algeria. A typical apartment is chosen to run the calculations under three different climates of Algeria. The simulation results obtained for the city of Annaba show that the use of rock wool, cork, expanded polystyrene and airgel insulation allows a reduction of 42.81%, 43.08%, 43.31% and 50.90% respectively. While for the city of Setif the reduction obtained is 34.15%, 34.70%, 35.13% and 52.25% respectively for the same insulation. For the city of Biskra the reduction is 32.07%, 32.28%, 32.45% and 38.72% respectively for the same insulation. The improvement of the thermal performance of the structure and the glazed surfaces according to the Passivhaus standard allows a significant reduction of heating and air conditioning needs estimated at 72, 78.21 and 65.21% respectively for the cities of Annaba, Setif and Biskra. A low energy consumption building is obtained for the city of Annaba and Setif.

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A review on heat transfer in nanoporous silica aerogel insulation materials and its modeling

Cited by 16 publications

References 130 publications

3D Electrospinning of Al2O3/ZrO2 Fibrous Aerogels for Multipurpose Thermal Insulation

3D Electrospinning of Al2O3/ZrO2 Fibrous Aerogels for Multipurpose Thermal Insulation

3D Electrospinning of Al2O3/ZrO2 fibrous aerogels for multipurpose thermal insulation

Nano technology building insulation effect on the thermal behavior of building under different Algerian weather

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