scholarly journals Thermal Conductivity of the Ga-In System: Experimental Measurements and CALPHAD Modeling

2020 ◽  
Author(s):  
Parker Maivald ◽  
Soumya Sridar ◽  
Wei Xiong
Keyword(s):  
Thermal Conductivity ◽  
Phase Region ◽  
Consumer Electronics ◽  
Thermal Interface Material ◽  
Two Phase ◽  
Diagram Method ◽  
Thermal Conductivity Parameter ◽  
Conductivity Parameter ◽  
Efficient Heat Transfer ◽  
Thermal Conductivities

Thermal interface material (TIM) that can exist as liquid at the service temperature enables efficient heat transfer across two adjacent surfaces in electronic applications. In this work, the thermal conductivities of different phase regions in the Ga-In system at various compositions and temperatures are measured for the first time. A modified comparative cut bar technique is used for the measurement of the thermal conductivities of InxGa1-x (x=0, 0.1, 0.214, 0.3, and 0.9) alloys at 40, 60, 80, and 100oC that are the temperatures commonly encountered in consumer electronics. The thermal conductivity values for the liquid and semi-liquid (liquid+β) Ga-In alloys are higher than the TIM currently used in consumer electronics. These measured quantities, along with the available experimental data from the literature, served as input for the thermal conductivity parameter optimization using the CALPHAD (CALculation of PHase Diagram) method for the pure elements, solution phase, and two-phase region. A set of self-consistent parameters for the description of the thermal conductivity of the Ga-In system is obtained. There is good agreement between the measured and calculated thermal conductivity values for all the phases. Hence, it can be envisaged that liquid/semi-liquid Ga-In alloys can be considered as a potential TIM in consumer electronics due to its high thermal conductivity.

scholarly journals Thermal Conductivity Determination of Ga-In Alloys for Thermal Interface Materials Design

Thermo ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 1-13
Author(s):  
Parker Maivald ◽  
Soumya Sridar ◽  
Wei Xiong
Keyword(s):  
Thermal Conductivity ◽  
Phase Region ◽  
Consumer Electronics ◽  
Thermal Interface Material ◽  
Two Phase ◽  
Thermal Interface ◽  
Thermal Conductivity Parameter ◽  
Conductivity Parameter ◽  
Efficient Heat Transfer ◽  
Thermal Conductivities

Thermal interface material (TIM) that exists in a liquid state at the service temperature enables efficient heat transfer across two adjacent surfaces in electronic applications. In this work, the thermal conductivities of different phase regions in the Ga-In system at various compositions and temperatures are measured for the first time. A modified comparative cut bar technique is used for the measurement of the thermal conductivities of GaxIn1−x (x = 0, 0.1, 0.214, 0.3, and 0.9) alloys at 40, 60, 80, and 100 °C, the temperatures commonly encountered in consumer electronics. The thermal conductivity of liquid and semi-liquid (liquid + β) Ga-In alloys are higher than most of the TIM’s currently used in consumer electronics. These measured quantities, along with the available experimental data from literature, served as input for the thermal conductivity parameter optimization using the CALPHAD (calculation of phase diagrams) method for pure elements, solution phase, and two-phase region. A set of self-consistent parameters for the description of the thermal conductivity of the Ga-In system is obtained. There is good agreement between the measured and calculated thermal conductivities for all of the phases. Due to their ease of manufacturing and high thermal conductivity, liquid/semi-liquid Ga-In alloys have significant potential for TIM in consumer electronics.

Entropy generation analysis for peristalsis of magneto Jeffrey materials

2021 ◽  
pp. 095440892110412
Author(s):  
Tasawar Hayat ◽  
Farhat Bibi ◽  
Ambreen Afsar Khan ◽  
Akbar Zaman ◽  
Ahmed Alsaedi
Keyword(s):  
Magnetic Field ◽  
Thermal Conductivity ◽  
Entropy Generation ◽  
Thermal Conductivity Coefficient ◽  
Temperature Dependent ◽  
Thermal Fields ◽  
Thermal Conductivity Parameter ◽  
Conductivity Parameter ◽  
Temperature Dependent Thermal Conductivity ◽  
Heat Transfer Parameter

This article communicates peristalsis of Jeffrey material in curved geometry. Here, material has temperature-dependent thermal conductivity and viscosity. Mathematical modeling of an inclined magnetic field in curved configuration has been presented in this article. Irreversibility effects have been analyzed through entropy generation. Slip conditions are entertained both for velocity and thermal fields. Problem is first reduced in wave frame and then lubrication approach has been utilized. Numerical solution of dimensionless problem is obtained and important parameters of curiosity are examined. It is noticed that velocity enhances for higher viscosity whereas temperature decreases for higher thermal conductivity coefficient. Velocity of the flow is maximum for inclination of magnetic field to be zero and it is minimum for [Formula: see text] Heat transfer parameter enhances both for thermal conductivity parameter and Hartmann number. Temperature is high for curved configuration when compared with straight channel. It is observed that entropy remains unchanged in center of the channel and it is maximum near the channel walls. Entropy generation decays near the channel walls by higher viscosity and thermal conductivity parameters. However, entropy is more for higher inclination of magnetic field.

Numerical Investigation of the Steady State Operation of a Cylindrical Capillary Pumped Loop Evaporator

2000 ◽  
Author(s):  
Y. H. Yan ◽  
J. M. Ochterbeck
Keyword(s):  
Thermal Conductivity ◽  
Heat Flux ◽  
Steady State ◽  
Effective Thermal Conductivity ◽  
Liquid Core ◽  
Phase Region ◽  
Capillary Pumped Loop ◽  
Two Phase ◽  
Cylindrical Capillary ◽  
Wick Structure

Abstract A two-dimensional numerical model was established to study the behavior of a cylindrical capillary pumped loop evaporator under steady-state operations. The influence of heat load, liquid subcooling and effective thermal conductivity of the wick structure on the evaporator performance were studied. It was found that increasing the applied heat flux and degree of liquid subcooling resulted in a decrease the temperature in the liquid core. This helped to prevent the vapor from generating in the liquid core and decreased the length of the two phase region in the wick structure. Decreasing the effective thermal conductivity also decreases the temperature in the liquid core as related to the back wick condition. It was observed that for a given liquid subcooling, a minimum heat flux exists below which vapor will generate in the liquid core and render the evaporator non-operational. It was also observed that for a given heat flux, a minimum required liquid subcooling exists. Vapor may form in the liquid core when the liquid subcooling is less than the minimum value.

Thermoelectric Properties of Nb-Doped SrTiO3 / TiO2 Multiphase Composite

2009 ◽  
Vol 1166 ◽  
Author(s):  
Kiyoshi Fuda ◽  
Kenji Murakami ◽  
Tomoyoshi Shoji ◽  
Shigeaki Sugiyama
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Figure Of Merit ◽  
Fine Particles ◽  
Phase Region ◽  
The Other ◽  
Two Phase ◽  
Typical Size ◽  
Dimensionless Figure Of Merit ◽  
Multiphase Composite

AbstractIn this study, we fabricated and examined a series of multiphase type composites constructed of Nb-doped SrTiO3 / TiO2 fine particles. The composition of the composites and the sintering temperatures were selected in a two-phase region where a perovskite SrTiO3 and a rutile TiO2 phases coexist. The composites obtained here were found to commonly have a mosaic type texture constructed of TiO2 and SrTiO3 fine particles with a typical size of about 500 nm. In some samples we also found additive phases such as Sr6Ti7Nb9O42. The thermal conductivity values measured for the most samples with different contents are ranged between 2 and 5 Wm-1K-1. The values are apparently lower than the value for single crystal SrTiO3 samples presented in literature. A sample with rather low relative density of about 80% showed a quite low thermal conductivity, about 1 Wm-1K-1. Taking account the other TE data, e.g. Seebeck coefficient and electrical conductivity, we calculated dimensionless figure of merit, ZT, to be at maximum 0.24 at 600°C.

A Study on Uncertainties in Estimations of Thermal Conductivity of Alumina Nanofluids

2015 ◽  
Vol 809-810 ◽  
pp. 525-530 ◽  
Author(s):  
Madalina Georgiana Moldoveanu ◽  
Alina Adriana Minea
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Transfer Performance ◽  
Unsolved Problem ◽  
Volume Fraction ◽  
Solid Particles ◽  
Two Phase ◽  
Polymeric Particles ◽  
Semi Empirical ◽  
Thermal Conductivities

An innovative way of improving the thermal conductivities of fluids is to suspend small solid particles in the fluids. Various types of powders such as metallic, non-metallic and polymeric particles can be added into fluids to form slurries. The thermal conductivities of fluids with suspended particles are expected to be higher than that of common fluids. Application of nanoparticles provides an effective way of improving heat transfer characteristics of fluids. By suspending nanophase particles in heating or cooling fluids, the heat transfer performance of the fluid can be significantly improved. Moreover, the thermal conductivity of nanofluid is strongly dependent on the nanoparticle volume fraction. So far it has been an unsolved problem to develop a sophisticated theory to predict thermal conductivity of nanofluids, although there are some semi empirical correlations to calculate the apparent conductivity of two-phase mixture. In this article few correlations were considered and differences were noted between different theories. In conclusion, a lot of uncertainties in determining thermal conductivity were noticed.

Flow and Heat Transfer of Powell–Eyring Fluid due to an Exponential Stretching Sheet with Heat Flux and Variable Thermal Conductivity

2015 ◽  
Vol 70 (3) ◽  
pp. 163-169 ◽  
Author(s):  
Ahmed M. Megahed
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Flux ◽  
Differential Equations ◽  
Variable Thermal Conductivity ◽  
Physical Parameters ◽  
Flow And Heat Transfer ◽  
Non Linear ◽  
Thermal Conductivity Parameter ◽  
Conductivity Parameter

AbstractAn analysis was carried out to describe the problem of flow and heat transfer of Powell–Eyring fluid in boundary layers on an exponentially stretching continuous permeable surface with an exponential temperature distribution in the presence of heat flux and variable thermal conductivity. The governing partial differential equations describing the problem were transformed into a set of coupled non-linear ordinary differential equations and then solved with a numerical technique using appropriate boundary conditions for various physical parameters. The numerical solution for the governing non-linear boundary value problem is based on applying the shooting method over the entire range of physical parameters. The effects of various parameters like the thermal conductivity parameter, suction parameter, dimensionless Powell–Eyring parameters and the Prandtl number on the flow and temperature profiles as well as on the local skin-friction coefficient and the local Nusselt number are presented and discussed. In this work, special attention was given to investigate the effect of the thermal conductivity parameter on the velocity and temperature fields above the sheet in the presence of heat flux. The numerical results were also validated with results from a previously published work on various special cases of the problem, and good agreements were seen.

scholarly journals Two dominant analytical methods for thermal analysis of convective step fin with variable thermal conductivity

2014 ◽  
Vol 18 (2) ◽  
pp. 431-442 ◽  
Author(s):  
Mohsen Torabi ◽  
Hessameddin Yaghoobi
Keyword(s):  
Thermal Conductivity ◽  
Homotopy Perturbation Method ◽  
Variational Iteration Method ◽  
Transformation Method ◽  
Variable Thermal Conductivity ◽  
Step Change ◽  
Homotopy Perturbation ◽  
Thermal Conductivity Parameter ◽  
Conductivity Parameter ◽  
Accurate Numerical Solution

Heat transfer in a straight fin with a step change in thickness and variable thermal conductivity which is losing heat by convection to its surroundings is developed via differential transformation method (DTM) and variational iteration method (VIM). In this study, we compare DTM and VIM results, with those of homotopy perturbation method (HPM) and an accurate numerical solution to verify the accuracy of the proposed methods. As an important result, it is depicted that the DTM results are more accurate in comparison with those obtained by VIM and HPM. After these verifications the effects of parameters such as thickness ratio, ?, dimensionless fin semi thickness,?, length ratio, ?, thermal conductivity parameter, ?, Biot number, Bi, on the temperature distribution are illustrated and explained.

scholarly journals Si-Ge whiskers for thermoelectric sensors design

2020 ◽  
Vol 21 (3) ◽  
pp. 399-403
Author(s):  
A.A. Druzhinin ◽  
I.P. Ostrovskii ◽  
Yu.M. Khoverko ◽  
N.S. Liakh-Kaguy
Keyword(s):  
Thermal Conductivity ◽  
Seebeck Coefficient ◽  
Humidity Sensor ◽  
Cvd Method ◽  
Temperature Dependences ◽  
Thermal Conductivity Parameter ◽  
Conductivity Parameter ◽  
Thermoelectric Parameters ◽  
Good Coincidence

The paper deals with studies of thermoelectric properties for Si1-xGex (x=0.01-0.05) whiskers doped with boron during their growth by CVD method. Temperature dependences of the resistance and the Seebeck coefficient for Si1-xGex whiskers were measured in the temperature range 275–550 K. A method for determination of thermoelectric parameters of the whisker was proposed with use of the whisker joints, which allows us to define a ratio of Seebeck coefficient to thermal conductivity a/k. Taking into account the obtained values of Seebeck coefficient, the whisker conductance and estimated values of thermal conductivity, parameter ZT was calculated for the whiskers and consists of 0.15 for T=200oC. The obtained value of ZT is in good coincidence with literature data for hop pressed Si-Ge nanocomposites. The humidity sensor was designed base on Si-Ge whiskers.

scholarly journals Effect of Thermal Conductivity on Magnetohydrodynamic Heat and Mass Transfer in Porous Medium Saturated with Kuvshinshiki Fluid

2017 ◽  
Vol 2 (2) ◽  
Author(s):  
Amos S Idowu ◽  
Abdulwaheed Jimoh
Keyword(s):  
Thermal Conductivity ◽  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Sherwood Number ◽  
Porous Plate ◽  
Elastic Parameter ◽  
Thermal Conductivity Parameter ◽  
Conductivity Parameter ◽  
The Impact ◽  
Transfer Flow

The effects of Kuvshinshiki fluid on Magnetohydrodynamic (MHD) heat and mass transfer flow over a vertical porous plate with chemical reaction of nth order and thermal conductivity was carried out. The governing partial differential equations were solved numerically using implicit Crank-Nicolson method. A parametric study was performed to illustrate the impact of visco-elastic parameter, radiation parameter, thermal conductivity parameter, magnetic parameter, Prandtl number on the velocity,temperature and concentration profiles.The results were presented graphically with tabular presentations of the skin-friction,rate of heat and mass transfer which were all computed and discussed for different values of parameters of the problem. The numerical results revealed that the visco- elastic of Kuvshinshiki fluid type is growing as concentration profile increases, while the velocity and temperature profile falls ,then the radiation and thermal conductivity were growing as velocity and temperature increases. Also Sherwood number decreases as radiation increases but Sherwood number remains unchanged as thermal conductivity growing.

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