scholarly journals A High-Accuracy Thermal Conductivity Model for Water-Based Graphene Nanoplatelet Nanofluids

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 5178
Author(s):  
Elif Begum Elcioglu
Keyword(s):  
Thermal Conductivity ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
High Accuracy ◽  
Conductivity Data ◽  
Graphene Nanoplatelet ◽  
Independent Variables ◽  
Thermal Conductivity Data ◽  
Thermal Conductivities

High energetic efficiency is a major requirement in industrial processes. The poor thermal conductivity of conventional working fluids stands as a limitation for high thermal efficiency in thermal applications. Nanofluids tackle this limitation by their tunable and enhanced thermal conductivities compared to their base fluid counterparts. In particular, carbon-based nanoparticles (e.g., carbon nanotubes, graphene nanoplatelets, etc.) have attracted attention since they exhibit thermal conductivities much greater than those of metal-oxide and metallic nanoparticles. In this work, thermal conductivity data from the literature are processed by employing rigorous statistical methodology. A high-accuracy regression equation is developed for the prediction of thermal conductivity of graphene nanoplatelet-water nanofluids, based on the temperature (15–60 °C), nanoparticle weight fraction (0.025–0.1 wt.%), and graphene nanoparticle specific surface area (300–750 m2/g). The strength of the impact of these variables on the graphene nanoplatelet thermal conductivity data can be sorted from the highest to lowest as temperature, nanoparticle loading, and graphene nanoplatelet specific surface area. The model developed by multiple linear regression with three independent variables has a determination coefficient of 97.1% and exhibits convenience for its ease of use from the existing prediction equations with two independent variables.

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

Effect of specific surface area on convective heat transfer of graphene nanoplatelet aqueous nanofluids

2015 ◽  
Vol 68 ◽  
pp. 100-108 ◽  
Author(s):  
Mohammad Mehrali ◽  
Emad Sadeghinezhad ◽  
Marc A. Rosen ◽  
Sara Tahan Latibari ◽  
Mehdi Mehrali ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Specific Surface ◽  
Convective Heat Transfer ◽  
Surface Area ◽  
Specific Surface Area ◽  
Convective Heat ◽  
Graphene Nanoplatelet

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.

Synthesis and Characterization of Silica Aerogel Materials Doped with TiO2 Powder for Thermal Insulation

2016 ◽  
Vol 723 ◽  
pp. 492-496
Author(s):  
Guang Wu Liu ◽  
Yan Gang Liu
Keyword(s):  
Surface Modification ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Silica Aerogel ◽  
High Performance ◽  
Silica Aerogels ◽  
Molar Ratio ◽  
Composite Aerogel ◽  
Thermal Conductivities

Super insulation and hydrophobic silica-based aerogels doped with TiO2 powder (8wt %) were successfully synthesized by using cost effective processing from Tetraeth oxysilane (TEOS). After aging and washing of wet gel, surface modification were modified using trimethylchlorosilane (TMCS) via one-step solvent exchange and surface modification. And the proper molar ratio of TMCS to pore water is 0.02. The microstructure and morphology of the ultralow density silica aerogels were characterized by the specific surface area, SBET, SEM, and the pore size distribution techniques. From the results, the obtained aerogel doped with TiO2 powder exhibited excellent physical properties with less than 10% volume shrinkage, extremely high specific surface area (652 m2/g) and super hydrophobicity (contact angle of~145°). It should be noted that TiO2 powders are physically embedded by SiO2 aerogel, and there is an obvious Ti–O–Ti and Si–O–Si bonding group based on structural analysis. The thermal properties of silica aerogel were determined using the Hot Disk device, composite aerogel exhibited thermal conductivities of 0.0426 W/m·K at 700°C, TiO2 powders effectively suppressed the intensified thermal radiations at high temperatures to achieve ultralow thermal conductivities. These results have important implications for designing novel structure of porous materials of high performance for silica aerogels.

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.

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