scholarly journals Structure, specific surface area and thermal conductivity of the snowpack around Barrow, Alaska

2012 ◽  
Vol 117 (D14) ◽  
pp. n/a-n/a ◽  
Author(s):  
Florent Domine ◽  
Jean-Charles Gallet ◽  
Josué Bock ◽  
Samuel Morin
Keyword(s):  
Thermal Conductivity ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area

scholarly journals Thermal conductivity of polyvinylpolymethylsiloxane aerogels with high specific surface area

RSC Advances ◽  
2019 ◽  
Vol 9 (14) ◽  
pp. 7833-7841 ◽  
Author(s):  
Lukai Wang ◽  
Junzong Feng ◽  
Yonggang Jiang ◽  
Liangjun Li ◽  
Jian Feng
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Energy Storage ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Heat Insulation ◽  
High Specific Surface Area

The traditional SiO2 aerogels are difficult to apply in the fields of energy storage and heat insulation due to their poor mechanical properties.

Porosity, Specific Surface Area and Effective Thermal Conductivity of Anisotropic Open Cell Lattice Structures

2005 ◽  
Author(s):  
Kiran Balantrapu ◽  
Deepti Rao Sarde ◽  
Christopher M. Herald ◽  
Richard A. Wirtz
Keyword(s):  
Thermal Conductivity ◽  
Specific Surface ◽  
Effective Thermal Conductivity ◽  
Surface Area ◽  
Specific Surface Area ◽  
Structural Characteristics ◽  
Analytical Models ◽  
Lattice Structures ◽  
Open Cell ◽  
Thermally Conductive

Open-cell box-lattice structures consisting of mutually orthogonal thermally conductive cylindrical ligaments can be configured to have wide ranging porosity, a large specific surface area and effective thermal conductivity in a particular direction together with specified structural characteristics. Thermal and mechanical properties can be tuned (and anisotropy introduced) by specification of different filament diameter and pitch for the vertical and horizontal filaments. Analytical models for porosity, specific surface area and effective thermal conductivity of lattice structures having different ligament diameters and pitches (anisotropy) are developed. The models show that all three of these quantities are functions of three dimensionless lengths.   This paper was also originally published as part of the Proceedings of the ASME 2005 Heat Transfer Summer Conference.

scholarly journals Meteorological, snow and soil data (2013–2019) from a herb tundra permafrost site at Bylot Island, Canadian high Arctic, for driving and testing snow and land surface models

2021 ◽  
Author(s):  
Florent Domine ◽  
Georg Lackner ◽  
Denis Sarrazin ◽  
Mathilde Poirier ◽  
Maria Belke-Brea
Keyword(s):  
Thermal Conductivity ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
High Arctic ◽  
Specific Humidity ◽  
The Arctic ◽  
Canadian High Arctic ◽  
Validation Data ◽  
Bylot Island

Abstract. Seasonal snow covers Arctic lands 6 to 10 months of the year and is therefore an essential element of the Arctic geosphere and biosphere. Yet, even the most sophisticated snow physics models are not able to simulate fundamental physical properties of Arctic snowpacks such as density, thermal conductivity and specific surface area. The development of improved snow models is in progress but testing requires detailed driving and validation data for high Arctic herb tundra sites, which are presently not available. We present 6 years of such data for an ice-wedge polygonal site in the Canadian high Arctic, in Qarlikturvik valley on Bylot Island at 73.15 °N. The site is on herb tundra with no erect vegetation and thick permafrost. Detailed soil properties are provided. Driving data are comprised of air temperature, air relative and specific humidity, wind speed, short wave and long wave downwelling radiation, atmospheric pressure and precipitation. Validation data include time series of snow depth, shortwave upwelling radiation, surface temperature, snow temperature profiles, soil temperature and water content profiles at five depths, snow thermal conductivity at three heights and soil thermal conductivity at 10 cm depth. Field campaigns in mid-May for 5 of the 6 years of interest provided spatially-averaged snow depths and vertical profiles of snow density and specific surface area in the polygon of interest and at other spots in the valley. Data are available at https://doi.org/10.5885/45693CE-02685A5200DD4C38 (Domine et al., 2021). Data files will be updated as more years of data become available.

In-Plane Effective Thermal Conductivity of Symmetric, Diamond-Weave Screen Laminates

2004 ◽  
Vol 127 (3) ◽  
pp. 353-356 ◽  
Author(s):  
Jun Xu ◽  
Richard A. Wirtz
Keyword(s):  
Thermal Conductivity ◽  
Specific Surface ◽  
Effective Thermal Conductivity ◽  
Surface Area ◽  
Specific Surface Area ◽  
Laboratory Experiments ◽  
Two Dimensional ◽  
Algebraic Models ◽  
Metal Fractions

Algebraic models of porosity, specific surface area, and in-plane effective thermal conductivity for stacked, two-dimensional symmetric diamond-weave screen laminations are developed and benchmarked with laboratory experiments. Diamond-weave laminations are found to have greater metal fractions and specific surface area than equivalent orthogonal-weaves. With the weave angle smaller than 90°, the structure also has a much higher effective thermal conductivity.

Monolithic silicon nitride-based aerogels with large specific surface area and low thermal conductivity

2019 ◽  
Vol 45 (13) ◽  
pp. 16331-16337 ◽  
Author(s):  
Yong Kong ◽  
Jiayue Zhang ◽  
Zhiyang Zhao ◽  
Xing Jiang ◽  
Xiaodong Shen
Keyword(s):  
Thermal Conductivity ◽  
Silicon Nitride ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Large Specific Surface Area ◽  
Low Thermal Conductivity

scholarly journals Tuning the Mechanical and Thermal Properties of Hydroxypropyl Methylcellulose Cryogels with the Aid of Surfactants

Gels ◽  
2021 ◽  
Vol 7 (3) ◽  
pp. 118
Author(s):  
Rafael S. Dezotti ◽  
Laíse M. Furtado ◽  
Márcio Yee ◽  
Ticiane S. Valera ◽  
Krishnasamy Balaji ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Specific Surface ◽  
Interaction Energy ◽  
Surface Area ◽  
Specific Surface Area ◽  
Hydroxypropyl Methylcellulose ◽  
Hydroxyl Group ◽  
Sulfonate Group ◽  
Mechanical And Thermal Properties

The mechanical and thermal properties of cryogels depend on their microstructure. In this study, the microstructure of hydroxypropyl methylcellulose (HPMC) cryogels was modified by the addition of ionic (bis (2-ethylhexyl) sodium sulfosuccinate, AOT) and non-ionic (Kolliphor® EL) surfactants to the precursor hydrogels (30 g/L). The surfactant concentrations varied from 0.2 mmol/L to 3.0 mmol/L. All of the hydrogels presented viscous behavior (G″ > G′). Hydrogels containing AOT (c > 2.0 mmol/L) led to cryogels with the lowest compressive modulus (13 ± 1 kPa), the highest specific surface area (2.31 m2/g), the lowest thermal conductivity (0.030 W/(m·°C)), and less hygroscopic walls. The addition of Kolliphor® EL to the hydrogels yielded the stiffest cryogels (320 ± 32 kPa) with the lowest specific surface area (1.11 m2/g) and the highest thermal conductivity (0.055 W/(m·°C)). Density functional theory (DFT) calculations indicated an interaction energy of −31.8 kcal/mol due to the interaction between the AOT sulfonate group and the HPMC hydroxyl group and the hydrogen bond between the AOT carbonyl group and the HPMC hydroxyl group. The interaction energy between the HPMC hydroxyl group and the Kolliphor®EL hydroxyl group was calculated as −7.91 kcal/mol. A model was proposed to describe the effects of AOT or Kolliphor®EL on the microstructures and the mechanical/thermal properties of HPMC cryogels.

scholarly journals Influence of Aging Factors on the Properties of Aerogels with Different Degrees of Granulation

2019 ◽  
Vol 27 (4(136)) ◽  
pp. 50-58 ◽  
Author(s):  
Agnieszka Greszta ◽  
Sylwia Krzemińska ◽  
Małgorzata Okrasa
Keyword(s):  
Thermal Conductivity ◽  
High Temperature ◽  
Thermal Radiation ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Moisture Absorption ◽  
Reference Sample ◽  
Absorption Capacity ◽  
Aging Factors

Aerogels are distinguished by their low density and thermal conductivity, which predisposes them for application in materials against extremely low or high temperature. Aerogel resistance to aging factors such as moisture, high temperature and thermal radiation was studied. Aerogel resistance to moisture absorption was studied by the weight method, at a relative humidity of 65% and 95%. For aerogels exposed to heat (at 260 °C) and thermal radiation (heat flux density 20 kW/m2), structural and textural characteristics (specific surface area, pore volume, pore size distribution) were determined. It was found that in an environment characterised by 95% humidity, the moisture weight absorbed was similar for all aerogels and amounted to less than 1%, corresponding to low moisture absorption capacity. The most significant changes in specific surface area were recorded for aerogels in powder form, where the value of this parameter after exposure to high temperature increased by 13% compared to the reference sample. An increase in the specific surface area can effect a reduction in thermal conductivity; thus this change is positive in character in the context of application to clothing designed against thermal factors.

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