Thermal-Conductivity Enhancement of Microfluids With Ni3(μ3-ppza)4Cl2 Metal String Complex Particles

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Baghir A. Suleimanov ◽  
Hakim F. Abbasov ◽  
Fuad F. Valiyev ◽  
Rayyat H. Ismayilov ◽  
Shie-Ming Peng
Keyword(s):  
Thermal Conductivity ◽  
Thermal Conductivity Enhancement ◽  
Water Molecules ◽  
Glycerol Solution ◽  
Transient Hot Wire ◽  
Colloidal Structure ◽  
Conductivity Enhancement ◽  
Water Glycerol ◽  
Wire Method ◽  
Particle Assemblies

The thermal conductivity of microfluids comprising Ni3(μ3-ppza)4Cl2 metal string complex (MSC) microparticles in an aqueous glycerol solution was investigated using the transient hot-wire method. A comparative analysis of the thermal-conductivity enhancements of microfluids and nanofluids revealed that the best results were achieved using microparticles of monocrystalline MSCs Ni3(μ3-ppza)4Cl2 as well as Ni5(μ5-pppmda)4Cl2 micro- and copper nanoparticles. Compared to the base fluid, the thermal-conductivity enhancements were 72% for Ni3–water–glycerol, 53% for Cu–water–glycerol, and 47% for Ni5–water–glycerol. It is shown that the high thermal-conductivity enhancement achieved with Ni3 microfluids is a result of higher stability in compare with nanofluid due to the lower density of the microparticles and the formation of particle assemblies. Therefore, the formation of hydrogen bonds between the MSC particles (through their organic fragments) and water molecules, takes place. Colloidal structure of Ni3-microfluids has a significant impact on their thermophysical properties.

Critical Invalidation of Temperature Dependence of Nanofluid Thermal Conductivity Enhancement

2013 ◽  
Vol 135 (5) ◽  
Author(s):  
Kisoo Han ◽  
Wook-Hyun Lee ◽  
Clement Kleinstreuer ◽  
Junemo Koo
Keyword(s):  
Thermal Conductivity ◽  
Natural Convection ◽  
Temperature Dependence ◽  
Temperature Limit ◽  
Thermal Conductivity Enhancement ◽  
Supporting Evidence ◽  
Conductivity Enhancement ◽  
Wide Range ◽  
Wire Method ◽  
The Impact

Of interest is the accurate measurement of the enhanced thermal conductivity of certain nanofluids free from the impact of natural convection. Owing to its simplicity, wide range of applicability and short response time, the transient hot-wire method (THWM) is frequently used to measure the thermal conductivity of fluids. In order to gain a sufficiently high accuracy, special care should be taken to assure that each measurement is not affected by initial heat supply delay, natural convection, and signal noise. In this study, it was found that there is a temperature limit when using THWM due to the incipience of natural convection. The results imply that the temperature-dependence of the thermal conductivity enhancement observed by other researchers might be misleading when ignoring the impact of natural convection; hence, it could not be used as supporting evidence of the effectiveness of micromixing due to Brownian motion. Thus, it is recommended that researchers report how they keep the impact of the natural convection negligible and check the integrity of their measurements in the future researches.

THERMAL CONDUCTIVITY ENHANCEMENT OF MATERIAL FOR CALCIUM CHLORIDE/WATER THERMOCHEMICAL ENERGY STORAGE

2018 ◽  
Author(s):  
Takuma Ohtaki ◽  
Maho Mitsuo ◽  
Takayuki Terauchi ◽  
Hiroshi Iguchi ◽  
Keiko Fujioka ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Energy Storage ◽  
Calcium Chloride ◽  
Thermal Conductivity Enhancement ◽  
Conductivity Enhancement ◽  
Chloride Water

scholarly journals Apparatus for routine measurements of the thermal conductivity of ice cores

1999 ◽  
Vol 29 ◽  
pp. 151-154 ◽  
Author(s):  
Crescenzo Festa ◽  
Aristide Rossi
Keyword(s):  
Thermal Conductivity ◽  
Ice Cores ◽  
Maximum Temperature ◽  
Transient Hot Wire ◽  
Hot Wire ◽  
Standard Samples ◽  
Experimental Conditions ◽  
Heating Source ◽  
Central Segment ◽  
Wire Method

AbstractAn apparatus is described for measuring the thermal conductivity of ice by the transient hot-wire method. Thermal conductivity A, is determined by tracking the thermal pulse induced in the sample by a heating source consisting of a platinum resistor. A central segment of the same platinum heating resistor acts also as a thermal sensor. A heat pulse transferred to the ice for a period of 40s gives a maximum temperature increment of about 7-14°C. In good experimental conditions, the expected reproducibility of the measurements is within ±3%. The accuracy of the method depends on whether the instrument has been calibrated by reliable standard samples, certified by absolute methods.

scholarly journals Anomalous thermal conductivity enhancement in low dimensional resonant nanostructures due to imperfections

Nanoscale ◽  
2021 ◽  
Author(s):  
Hongying Wang ◽  
Yajuan Cheng ◽  
Zheyong Fan ◽  
Yangyu Guo ◽  
Zhongwei Zhang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Energy Conversion ◽  
Thermal Conductivity Enhancement ◽  
Heat Management ◽  
Thermoelectric Energy Conversion ◽  
Conductivity Enhancement ◽  
Thermoelectric Energy ◽  
Low Dimensional

Nanophononic metamaterials have broad applications in fields such as heat management, thermoelectric energy conversion, and nanoelectronics. Phonon resonance in pillared low-dimensional structures has been suggested to be a feasible approach...

scholarly journals Thermal Conductivity of Ionic Liquids and IoNanofluids. Can Molecular Theory Help?

Fluids ◽  
2021 ◽  
Vol 6 (3) ◽  
pp. 116
Author(s):  
Xavier Paredes ◽  
Maria José Lourenço ◽  
Carlos Nieto de Castro ◽  
William Wakeham
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Ionic Liquids ◽  
Imaging Techniques ◽  
Interfacial Area ◽  
Thermal Conductivity Enhancement ◽  
Molecular Theory ◽  
Estimation Methods ◽  
Diphenyl Oxide ◽  
Conductivity Enhancement

Ionic liquids have been suggested as new engineering fluids, specifically in the area of heat transfer, and as alternatives to current biphenyl and diphenyl oxide, alkylated aromatics and dimethyl polysiloxane oils, which degrade above 200 °C, posing some environmental problems. Addition of nanoparticles to produce stable dispersions/gels of ionic liquids has proved to increase the thermal conductivity of the base ionic liquid, potentially contributing to better efficiency of heat transfer fluids. It is the purpose of this paper to analyze the prediction and estimation of the thermal conductivity of ionic liquids and IoNanofluids as a function of temperature, using the molecular theory of Bridgman and estimation methods previously developed for the base fluid. In addition, we consider methods that emphasize the importance of the interfacial area IL-NM in modelling the thermal conductivity enhancement. Results obtained show that it is not currently possible to predict or estimate the thermal conductivity of ionic liquids with an uncertainty commensurate with the best experimental values. The models of Maxwell and Hamilton are not capable of estimating the thermal conductivity enhancement of IoNanofluids, and it is clear that the Murshed, Leong and Yang model is not practical, if no additional information, either using imaging techniques at nanoscale or molecular dynamics simulations, is available.

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