Study on Heat Transfer and Corrosion Resistance of Anodized Aluminum Alloy in Gallium-Based Liquid Metal

2019 ◽  
Vol 141 (1) ◽  
Author(s):  
Yuntao Cui ◽  
Yujie Ding ◽  
Shuo Xu ◽  
Yushu Wang ◽  
Wei Rao ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Corrosion Resistance ◽  
Aluminum Alloy ◽  
Liquid Metal ◽  
Effective Thermal Conductivity ◽  
Anodic Oxidation ◽  
Convective Heat Transfer Coefficient ◽  
Total Thickness ◽  
Anodized Aluminum

Gallium-based liquid metal (LM) inherits excellent thermophysical properties and pollution-free characteristics. However, it has long been a fatal problem that LM would cause serious corrosion and embrittlement on the classical substrate made of aluminum alloys in constructing chip cooling device. Here, anodic oxidation treatment was introduced on processing the aluminum alloy aiming to tackle the corrosion issues. The prepared anodic oxidation aluminum (AAO) coatings were composed of nanopore layers and barrier layers on a high-purity alumina matrix that were manufactured electrochemically. According to the measurement, the effective thermal conductivity of the anodized aluminum alloy increases with the total thickness of sample increasing. When the total thickness L exceeds 5 × 10−3 m, effects of the porous media on effective thermal conductivity are negligible via model simulation and calculation. It was experimentally found that aluminum alloy after surface anodization treatment presented excellent corrosion resistance and outstanding heat transfer performance even when exposed in eutectic gallium–indium (E-GaIn) LM over 200 °C. The convective heat transfer coefficient of LM for anodized sample reached the peak when the heat load is 33.3 W.

850.0 and 852.0 ALUMINUM ALLOY BEARING BARS

Alloy Digest ◽  
1988 ◽  
Vol 37 (9) ◽  
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Corrosion Resistance ◽  
Aluminum Alloy ◽  
Heat Treating ◽  
Light Metal ◽  
General Purpose ◽  
High Ductility ◽  
Higher Temperature ◽  
Bearing Alloy

Abstract 850.0 ALUMINUM Alloy can be considered the general purpose light metal bearing alloy. Its good thermal conductivity keeps operating temperatures low. It has high ductility. In many applications it has been found to be superior to steel backed bearings. 852.0 ALUMINUM Alloy has higher mechanical properties making it suitable for heavier load and higher temperature applications. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and shear strength. It also includes information on corrosion resistance as well as heat treating and machining. Filing Code: Al-290. Producer or source: Federated Bronze Products Inc..

Figure of Merit-Based Optimization Approach of Phase Change Material-based Composites for Portable Electronics Using Simplified Model

2021 ◽  
Author(s):  
Ayushman Singh ◽  
Srikanth Rangarajan ◽  
Leila Choobineh ◽  
Bahgat Sammakia
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Phase Change ◽  
Effective Thermal Conductivity ◽  
Phase Change Material ◽  
Figure Of Merit ◽  
Volume Fraction ◽  
Simplified Model ◽  
Transient Temperature ◽  
Change Material

Abstract This work presents an approach to optimally designing a composite with thermal conductivity enhancers (TCEs) infiltrated with phase change material (PCM) based on figure of merit (FOM) for thermal management of portable electronic devices. The FOM defines the balance between effective thermal conductivity and energy storage capacity. In present study, TCEs are in the form of a honeycomb structure. TCEs are often used in conjunction with PCM to enhance the conductivity of the composite medium. Under constrained composite volume, the higher volume fraction of TCEs improves the effective thermal conductivity of the composite, while it reduces the amount of latent heat storage simultaneously. The present work arrives at the optimal design of composite for electronic cooling by maximizing the FOM to resolve the stated trade-off. In this study, the total volume of the composite and the interfacial heat transfer area between the PCM and TCE are constrained for all design points. A benchmarked two-dimensional direct CFD model was employed to investigate the thermal performance of the PCM and TCE composite. Furthermore, assuming conduction-dominated heat transfer in the composite, a simplified effective numerical model that solves the single energy equation with the effective properties of the PCM and TCE has been developed. The effective thermal conductivity of the composite is obtained by minimizing the error between the transient temperature gradient of direct and simplified model by iteratively varying the effective thermal conductivity. The FOM is maximized to find the optimal volume fraction for the present design.

scholarly journals Effective thermal conductivity of the hair coat of Holstein cows in a tropical environment

2009 ◽  
Vol 38 (11) ◽  
pp. 2218-2223 ◽  
Author(s):  
Alex Sandro Campos Maia ◽  
Roberto Gomes da Silva ◽  
João Batista Freire de Souza Junior ◽  
Rosiane Batista da Silva ◽  
Hérica Girlane Tertulino Domingos
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Free Convection ◽  
Effective Thermal Conductivity ◽  
Tropical Environment ◽  
Holstein Cows ◽  
Hair Coat ◽  
Black And White ◽  
Low K

The objective of the present study was to assess the effective thermal conductivity of the hair coat (k ef, mW.m-1.K-1) of Holstein cows in a tropical environment, as related to conduction and radiation in the absence of free convection. The average k ef was 49.72 mW.m-1.K-1, about twice the conductivity of the air (26 mW.m-1.K-1) and much less than that of the hair fibres (260 mW.m-1.K-1). The low k ef values were attributed mainly to the small cross area of individual hairs, ρef/ρf (17.2% and 21.3% for black and white hairs, respectively). White coats were denser, with longer hairs and significantly higher k ef (53.15 mW.m-1.K-1) than that of the black hairs (49.25 mW.m-1.K-1). The heritability coefficient of the effective thermal conductivity was calculated as h²=0.18 the possibility was discussed of selecting cattle for increased heat transfer through the hair coat.

Investigations on Transient Natural Convection in Boron Nitride-Mineral Oil Nanofluid Systems

2012 ◽  
Author(s):  
Shijo Thomas ◽  
C. B. Sobhan ◽  
Jaime Taha-Tijerina ◽  
T. N. Narayanan ◽  
P. M. Ajayan
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Transfer Coefficient ◽  
Natural Convection ◽  
Boron Nitride ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Convective Heat Transfer Coefficient ◽  
Mineral Oil

Nanofluids are suspensions or colloids produced by dispersing nanoparticles in base fluids like water, oil or organic fluids, so as to improve their thermo-physical properties. Investigations reported in recent times have shown that the addition of nanoparticles significantly influence the thermophysical properties, such as the thermal conductivity, viscosity, specific heat and density of base fluids. The convective heat transfer coefficient also has shown anomalous variations, compared to those encountered in the base fluids. By careful selection of the parameters such as the concentration and the particle size, it has been possible to produce nanofluids with various properties engineered depending on the requirement. A mineral oil–boron nitride nanofluid system, where an increased thermal conductivity and a reduced electrical conductivity has been observed, is investigated in the present work to evaluate its heat transfer performance under natural convection. The modified mineral oil is produced by chemically dispersing boron nitride nanoparticles utilizing a one step method to obtain a stable suspension. The mineral oil based nanofluid is investigated under transient free convection heat transfer, by observing the temperature-time response of a lumped parameter system. The experimental study is used to estimate the time-dependent convective heat transfer coefficient. Comparisons are made with the base fluid, so that the enhancement in the heat transfer coefficient under natural convection situation can be estimated.

Numerical Study on the Surface Convective Heat Transfer of Mass Concrete Structure

2015 ◽  
Vol 723 ◽  
pp. 992-995
Author(s):  
Biao Li ◽  
Fu Guo Tong ◽  
Chang Liu ◽  
Nian Nian Xi
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Flow Velocity ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Air Flow ◽  
Convective Heat Transfer Coefficient ◽  
Concrete Surface ◽  
Mass Concrete ◽  
Air Flow Velocity

The surface convective heat transfer of mass concrete is an important element of concrete structure temperature effect analysis. Based on coupled Thermal Fluid governing differential equation and finite element method, the paper calculated and analyzed the dependence of the concrete surface convective heat transfer on the air flow velocity and the concrete thermal conductivity coefficient. Results show that the surface convective heat transfer coefficient of concrete is a quadratic polynomial function of the air flow velocity, but influenced much less by the air flow velocity when temperature gradient is dominating in heat transfer. The concrete surface convective heat transfer coefficient increases linearly with the thermal conductivity of concrete increases.

Effective Thermal Conductivity of Submicron Powders: A Numerical Study

2016 ◽  
Vol 846 ◽  
pp. 500-505
Author(s):  
Wei Jing Dai ◽  
Yi Xiang Gan ◽  
Dorian Hanaor
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Thermal Resistance ◽  
Effective Thermal Conductivity ◽  
Granular Materials ◽  
Gas Phase ◽  
Numerical Study ◽  
Transfer Model ◽  
Size Of Particles ◽  
Contact Unit

Effective thermal conductivity is an important property of granular materials in engineering applications and industrial processes, including the blending and mixing of powders, sintering of ceramics and refractory metals, and electrochemical interactions in fuel cells and Li-ion batteries. The thermo-mechanical properties of granular materials with macroscopic particle sizes (above 1 mm) have been investigated experimentally and theoretically, but knowledge remains limited for materials consisting of micro/nanosized grains. In this work we study the effective thermal conductivity of micro/nanopowders under varying conditions of mechanical stress and gas pressure via the discrete thermal resistance method. In this proposed method, a unit cell of contact structure is regarded as one thermal resistor. Thermal transport between two contacting particles and through the gas phase (including conduction in the gas phase and heat transfer of solid-gas interfaces) are the main mechanisms. Due to the small size of particles, the gas phase is limited to a small volume and a simplified gas heat transfer model is applied considering the Knudsen number. During loading, changes in the gas volume and the contact area between particles are simulated by the finite element method. The thermal resistance of one contact unit is calculated through the combination of the heat transfer mechanisms. A simplified relationship between effective thermal conductivity and loading pressure can be obtained by integrating the contact units of the compacted powders.

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