High-porosity geopolymer foams with tailored porosity for thermal insulation and wastewater treatment

2017 ◽  
Vol 32 (17) ◽  
pp. 3251-3259 ◽  
Author(s):  
Chengying Bai ◽  
Giorgia Franchin ◽  
Hamada Elsayed ◽  
Alessandro Zaggia ◽  
Lino Conte ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Thermal Insulation ◽  
High Porosity ◽  
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Abstract

scholarly journals Thermal insulation properties of green vacuum insulation panel using wood fiber as core material

BioResources ◽  
2019 ◽  
Vol 14 (2) ◽  
pp. 3339-3351 ◽  
Author(s):  
Baowen Wang ◽  
Zhihui Li ◽  
Xinglai Qi ◽  
Nairong Chen ◽  
Qinzhi Zeng ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Bulk Density ◽  
Thermal Insulation ◽  
Wood Fiber ◽  
Core Material ◽  
High Porosity ◽  
Total Thermal Conductivity ◽  
Wood Fibers ◽  
Vacuum Insulation ◽  
Vacuum Insulation Panel

Wood fibers were prepared as core materials for a vacuum insulation panel (VIP) via a dry molding process. The morphology of the wood fibers and the microstructure, pore structure, transmittance, and thermal conductivity of the wood fiber VIP were tested. The results showed that the wood fibers had excellent thermal insulation properties and formed a porous structure by interweaving with one another. The optimum bulk density that led to a low-cost and highly thermally efficient wood fiber VIP was 180 kg/m3 to 200 kg/m3. The bulk density of the wood fiber VIP was 200 kg/m3, with a high porosity of 78%, a fine pore size of 112.8 μm, and a total pore volume of 7.0 cm3·g-1. The initial total thermal conductivity of the wood fiber VIP was 9.4 mW/(m·K) at 25 °C. The thermal conductivity of the VIP increased with increasing ambient temperature. These results were relatively good compared to the thermal insulation performance of current biomass VIPs, so the use of wood fiber as a VIP core material has broad application prospects.

Fabrication of ultra-high-porosity cordierite foams by the thermo-foaming of powder dispersions in molten D-glucose anhydrous

2019 ◽  
Vol 34 (10) ◽  
pp. 1818-1825 ◽  
Author(s):  
Xin Li ◽  
Yuanbing Li ◽  
Ruofei Xiang ◽  
Shujing Li ◽  
Qirun Zhou ◽  
...  
Keyword(s):  
High Porosity ◽  
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Abstract

scholarly journals Continuous, Strong, Porous Silk Firoin-Based Aerogel Fibers toward Textile Thermal Insulation

Polymers ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1899 ◽  
Author(s):  
Haiwei Yang ◽  
Zongqian Wang ◽  
Zhi Liu ◽  
Huan Cheng ◽  
Changlong Li
Keyword(s):  
Heat Transfer ◽  
Thermal Insulation ◽  
Hollow Fiber ◽  
High Performance ◽  
Large Scale ◽  
Low Density ◽  
Potential Candidate ◽  
Scale Production ◽  
Insulation Material ◽  
High Porosity

Aerogel fiber, with the characteristics of ultra-low density, ultra-high porosity, and high specific surface area, is the most potential candidate for manufacturing wearable thermal insulation material. However, aerogel fibers generally show weak mechanical properties and complex preparation processes. Herein, through firstly preparing a cellulose acetate/polyacrylic acid (CA/PAA) hollow fiber using coaxial wet-spinning followed by injecting the silk fibroin (SF) solution into the hollow fiber, the CA/PAA-wrapped SF aerogel fibers toward textile thermal insulation were successfully constructed after freeze-drying. The sheath (CA/PAA hollow fiber) possesses a multiscale porous structure, including micropores (11.37 ± 4.01 μm), sub-micron pores (217.47 ± 46.16 nm), as well as nanopores on the inner (44.00 ± 21.65 nm) and outer (36.43 ± 17.55 nm) surfaces, which is crucial to the formation of a SF aerogel core. Furthermore, the porous CA/PAA-wrapped SF aerogel fibers have many advantages, such as low density (0.21 g/cm3), high porosity (86%), high strength at break (2.6 ± 0.4 MPa), as well as potential continuous and large-scale production. The delicate structure of multiscale porous sheath and ultra-low-density SF aerogel core synergistically inhibit air circulation and limit convective heat transfer. Meanwhile, the high porosity of aerogel fibers weakens heat transfer and the SF aerogel cellular walls prevent infrared radiation. The results show that the mat composed of these aerogel fibers exhibits excellent thermal insulating properties with a wide working temperature from −20 to 100 °C. Therefore, this SF-based aerogel fiber can be considered as a practical option for high performance thermal insulation.

scholarly journals Thermal insulation property of graphene/polymer coated textile based multi-layer fabric heating element with aramid fabric

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Hyelim Kim ◽  
Han Seong Kim ◽  
Sunhee Lee
Keyword(s):  
Surface Temperature ◽  
Thermal Insulation ◽  
Temperature Difference ◽  
Protective Clothing ◽  
Woven Fabrics ◽  
Heating Element ◽  
Electrical Heating ◽  
High Porosity ◽  
Insulation Property ◽  
Thermal Insulation Property

Abstract This study investigated the thermal insulation properties based on electrical heating test of graphene-based multi-layer fabric heating elements to confirm the possibility of application for fabric heating element for protective clothing. Four layers were designed as layers of outer, filler, electrical heating textile, and lining. The outer fabrics used two different densities of aramid woven fabrics (LD_ARW and HD_ARW), an aramid knit (AR_KT), and nonwoven (AR_NW). Fabricated graphene/polymer coated electrical heating textile (GR) exhibits a surface temperature of about 85 °C, a current of 0.12 A, and a power of 3 W when 30 V is applied. As composed with 4-layer, the surface temperature of LD_ARW and HD_ARW used as the outer for sample indicated less than 50 °C, due to their excellent heat resistance property; whereas, when AR_KT and AR_NW were used, the temperature was about 50 °C. This is because their fine fibers form high porosity that can entrap air. As a result of the thermal insulation properties, the temperature difference of each layer was in the order ΔT(GR-N3) < ΔT(GR-Lining) < ΔT(GR-Outer). In particular, when AR_NW was used as the outer fabric, ΔT(GR-Outer) was decreased by about 10 °C, compared with that of the other outer fabric. By the effect of relative humidity under dry 25% RH and comfortable 55% RH, the temperature difference was decreased under 55% RH; thus, the thermal insulation property was improved under comfortable humidity condition. Therefore, the best thermal insulation performance was exhibited when AR_NW was used as outer under 55% RH, and it is expected to expand its application to fabric heating element for protective clothing.

Impact of high porosity on thermal transport in UO2 nuclear fuel

2013 ◽  
Vol 28 (17) ◽  
pp. 2308-2315 ◽  
Author(s):  
Di Yun ◽  
Marius Stan
Keyword(s):  
Nuclear Fuel ◽  
Thermal Transport ◽  
High Porosity ◽  
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Abstract

scholarly journals Physical and mechanical properties of composites based on hemp shives and lime

2018 ◽  
Vol 49 ◽  
pp. 00010 ◽  
Author(s):  
Przemysław Brzyski ◽  
Grzegorz Łagód
Keyword(s):  
Mechanical Properties ◽  
Thermal Insulation ◽  
Thermal Conductivity Coefficient ◽  
Positive Impact ◽  
Physical And Mechanical Properties ◽  
Wall Material ◽  
High Porosity ◽  
Plant Origin ◽  
Timber Frame ◽  
Properties Of Composites

One of the objectives of sustainable development in construction is the use of low-processed materials. They have a positive impact on the ecological balance of the building throughout the entire life cycle. Examples of such materials are materials of plant origin - straw, shives, cellulose fibers. They are used as thermal insulation or wall material. In recent years, hemp shives are increasingly used as a component of a lime-based composite, which performs the function of wall filling in timber frame constructions. The shives, due to the high porosity, determine the high thermal insulation properties of the composite. The physico-mechanical properties of the composite can be modified depending on various factors, including the ratio of hemp shives to the binder. The lime binder, in turn, can be modified by hydraulic and pozzolan additives. The paper presents mechanical properties (compressive and flexural strength) as well as physical properties (density, porosity, thermal conductivity coefficient, absorbability) of composites with various proportions of hemp shives of the Bialobrzeskie variety to the lime binder modified with Portland cement and metakaolinite.

Aerogel for Microsystems Thermal Insulation: System Design and Process Development

2005 ◽  
Author(s):  
Brian Smith ◽  
David Romero ◽  
Damena Agonafer ◽  
Jason Gu ◽  
Cristina H. Amon
Keyword(s):  
Thermal Insulation ◽  
Large Scale ◽  
Process Development ◽  
System Modeling ◽  
Dielectric Constants ◽  
Thermal Design ◽  
Small Scale ◽  
Thermal Testing ◽  
High Porosity ◽  
Crystal Oscillator

Extreme miniaturization in the microelectronics component market along with the emergence of system-on-chip applications has driven interest in correspondingly small-scale thermal management designs requiring novel material systems. This paper concentrates on aerogel, which is an amorphous, nanoporous dielectric oxide fabricated through a sol-gel process. Its extremely high porosity leads to very low thermal conductivity and dielectric constants. Significant research has been devoted to its electrical properties; however, there are several emerging applications that can leverage the thermal characteristics as well. Two promising applications are investigated in this paper: a monolithically integrated infrared sensor that requires thermal isolation between sensor and silicon substrate, and an ultra-miniature crystal oscillator device which demands thermal insulation of the crystal for low-power operation. This paper identifies the potential benefits of aerogel in these applications through system modeling, demonstrates aerogel’s compatibility with standard low-cost microfabrication techniques, and presents results of thermal testing of aerogel films compared with other microelectronics insulators and available data in the literature. The goal is to explore system thermal design using aerogel while demonstrating its feasibility through experimentation. The combination of numerical simulations, Bayesian surrogate modeling, and process development helps to refine candidate aerogel applications and allow the designer to explore thermal designs which have not previously been possible in large-scale microelectronics system production.   This paper was also originally published as part of the Proceedings of the ASME 2005 Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems.

Study of the mechanical and the thermal insulation properties of polyurethane coating containing chicken eggshell and rice husk ash as fillers

2016 ◽  
Vol 45 (5) ◽  
pp. 313-319 ◽  
Author(s):  
Bee Chin Ang ◽  
Norasikin Ahmad ◽  
Zhi Chao Ong ◽  
Shun Chi Cheok ◽  
Hui Fen Chan
Keyword(s):  
Thermal Conductivity ◽  
Thermal Insulation ◽  
Rice Husk ◽  
Rice Husk Ash ◽  
Dip Coating ◽  
Gravimetric Analysis ◽  
High Porosity ◽  
Coating System ◽  
Content Type ◽  
Chicken Eggshell

Purpose The main aim of this study was to examine the effects of chicken eggshell (CES) and rice husk ash (RHA) as fillers on the mechanical and the thermal insulation properties of polyurethane coatings. Design/methodology/approach CES and RHA were ground via ball milling set at different parameters, and the smallest particles size obtained were selected and used as fillers. Fillers of different weight proportions were mixed with other components such as binder, solvent and pigment to form various coating formulations and test samples were made via dip coating. A series of characterisations were conducted to analyse the thermal and mechanical properties of the coating. Findings The smallest particle size of CES and RHA was obtained after both of them had undergone grinding process at 400 rpm within 180 min. Morphological studies revealed that CES and RHA have irregular shape and high porosity. In crystallographic analysis, CES mainly composed of pure calcite crystal structure and RHA contained amorphous silica. Both of fillers were found thermally stable up to 520 and 710°C for RHA and CES, respectively. In RHA individual system, as the RHA proportion increases, the thermal conductivity of the coating declined. In contrast, in the CES coating system, the thermal conductivity demonstrated an opposite trend. Thermal gravimetric analysis results displayed that by adding hybrid fillers, the residue weight and the thermal stability of the coatings were increased. In addition, the adhesion strength of the coating was increased as the filler weight content increased. Research limitations/implications Fillers with nano-range size were expected to be produced in this research for better performance of the coating. However, the obtained fillers were limited to micron size through dry grinding method. Another drawback in this research was the coating technique which is dip coating. The coated substrates do not have uniform coating thickness and this subsequently influenced the performance. Originality/value A novel attempt has been made to study the formulation coating system by mixing CES and RHA as fillers which is also known as a hybrid system.

Dispersion of antimony doped tin oxide nanopowders for preparing transparent thermal insulation water-based coatings

2017 ◽  
Vol 32 (12) ◽  
pp. 2414-2422
Author(s):  
Hao Sun ◽  
Bingshan Liu ◽  
Xu Liu ◽  
Zuodong Yin
Keyword(s):  
Thermal Insulation ◽  
Tin Oxide ◽  
Water Based ◽  
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Abstract

scholarly journals The Perspective and Challenge of Nanomaterials in Oil and Gas Wastewater Treatment

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3945
Author(s):  
Xiaoying Liu ◽  
Wenlin Ruan ◽  
Wei Wang ◽  
Xianming Zhang ◽  
Yunqi Liu ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Oil And Gas ◽  
Membrane Separation ◽  
High Surface ◽  
High Porosity ◽  
Treatment Technology ◽  
Water Separation ◽  
Separation Technology ◽  
Oil Water Separation ◽  
Membrane Treatment

Oil and gas wastewater refers to the waste stream produced in special production activities such as drilling and fracturing. This kind of wastewater has the following characteristics: high salinity, high chromaticity, toxic and harmful substances, poor biodegradability, and a difficulty to treat. Interestingly, nanomaterials show great potential in water treatment technology because of their small size, large surface area, and high surface energy. When nanotechnology is combined with membrane treatment materials, nanofiber membranes with a controllable pore size and high porosity can be prepared, which provides more possibilities for oil–water separation. In this review, the important applications of nanomaterials in wastewater treatment, including membrane separation technology and photocatalysis technology, are summarized. Membrane separation technology is mainly manifested in ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO). It also focuses on the application of semiconductor photocatalysis technology induced by TiO2 in the degradation of oil and gas wastewater. Finally, the development trends of nanomaterials in oil and gas wastewater treatment are prospected.

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