scholarly journals Heat flux in a vibrated granular gas: the diffusive heat conductivity coefficient

2005 ◽  
Author(s):  
J. Javier Brey
Keyword(s):  
Heat Flux ◽  
Heat Conductivity ◽  
Heat Conductivity Coefficient ◽  
Granular Gas

scholarly journals Heat flux in a granular gas

2012 ◽  
Author(s):  
J. J. Brey ◽  
M. J. Ruiz-Montero
Keyword(s):  
Heat Flux ◽  
Granular Gas

THE INFLUENCE OF THE VALUE OF THE THERMAL FLUX SUPPLIED TO THE WALL ON THE SPATIAL DISTRIBUTION OF THE HEAT CONDUCTIVITY COEFFICIENT OF SUPERCRITICAL WATER IN THE CHANNELS

2017 ◽  
Author(s):  
Nataliia Fialko ◽  
◽  
Viktor Prokopov ◽  
Julii Sherenkovskiy ◽  
Sergey Aleshko ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Computer Modeling ◽  
Supercritical Water ◽  
Heat Conductivity ◽  
Thermal Flux ◽  
Heat Conductivity Coefficient ◽  
Tube System

The paper presents the results of computer modeling for research the regularities of the influence of the value of the thermal flux supplied to the tube system on the structure of the distribution of the heat conductivity of supercritical water in the channels.

Heat Transfer Characterizations of Heat Pipe in Comparison With Copper Pipe

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Chen-Ching Ting ◽  
Jing-Nang Lee ◽  
Chien-Chih Chen
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Source ◽  
Heat Pipe ◽  
Heat Conductivity ◽  
Cooling Efficiency ◽  
Copper Pipe ◽  
Heat Transfer Behavior ◽  
Transfer Behavior ◽  
Large Heat

The article presents some significant experimental data for studying the heat transfer behavior of heat pipe, which will further help the cooling efficiency improvement of the heat pipe cooler. It is well known that the heat pipe owns the extreme large heat conductivity and is often integrated with cooling plates for CPU cooling. The heat pipe uses special heat transfer techniques to obtain extremely large heat conductivity, which are the inside liquid evaporation for heat absorption and the inside microstructural capillarity for condensation. These special techniques yield the instant heat transfer from the heat source to the remote side directly, but the special heat transfer behavior is changed due to the integration with cooling plates. The destroyed heat transfer behavior of the heat pipe causes the cooling efficiency of the heat pipe cooler to be not able to reach a predicted good value. To improve the cooling efficiency of the heat pipe cooler we recover the original heat transfer behavior of the heat pipe integrated with cooling plates. This work first built a CPU simulator in accordance with the ASTM standard for heating the heat pipe, then uses the color schlieren technique to visualize the sequent heat flux nearby the heat pipe and the infrared thermal camera for quantitative temperature measurements synchronously. The result shows that the heat flux first appears at the opposite side from the heat source and there exhibits also the highest temperature. This is different from the heat transfer behavior of the copper pipe. Another very interesting result is that the heat flux of the cooling plate nearest to the heat source is first viewed than the others, which is similar to the integration with the copper pipe.

Large Heat Transport Due to Spontaneous Gas Oscillation Induced in a Tube With Steep Temperature Gradients

1983 ◽  
Vol 105 (4) ◽  
pp. 889-894 ◽  
Author(s):  
T. Yazaki ◽  
A. Tominaga ◽  
Y. Narahara
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Liquid Helium ◽  
Heat Conductivity ◽  
Room Temperature ◽  
Evaporation Rate ◽  
Experimental Studies ◽  
Temperature Gradients ◽  
Pressure Amplitude ◽  
Large Heat

This paper describes experimental studies of heat transfer due to the oscillations of gas columns that are spontaneously induced in a tube with steep temperature gradients. The tube (∼3 m in length) is closed at both ends and bent into U-shaped form at the midpoint. The temperature distribution along the tube is step-functional and symmetrical with respect to the midpoint. The warm part (closed-end sides) is maintained at room temperature and the cold one is immersed in liquid helium (4.2 K). The heat transported from the warm part to the cold is estimated from the evaporation rate of liquid helium. The heat flux by the oscillations is proportional to the square of the pressure amplitude, and the effective heat conductivity can be several orders of magnitude larger than the molecular heat conductivity of gas. The experimental results are compared with the theory of the second-order heat flux proposed by Rott and are found to be in satisfactory agreement with this.

scholarly journals Роль взаимодействия частиц в кластерной модели теплопроводности наножидкостей

2018 ◽  
Vol 44 (3) ◽  
pp. 17
Author(s):  
Б.В. Бошенятов
Keyword(s):  
Experimental Data ◽  
Continuum Mechanics ◽  
Heat Conductivity ◽  
Temperature Fields ◽  
Spherical Particles ◽  
Heat Conductivity Coefficient ◽  
Effective Heat Conductivity ◽  
Effective Heat ◽  
Individual Cluster

AbstractAnalytical dependences of the effective heat conductivity coefficient of an individual cluster and cluster nanofluid are obtained on the basis of classical equations of continuum mechanics with allowance for the interaction of temperature fields of spherical particles inside a cluster. The calculated dependences of the heat-conductivity coefficient of the cluster nanofluid agree with the corresponding experimental data.

scholarly journals The analysis of heat conductivity coefficient of the aerated concrete building barriers depending on moisture changes

2011 ◽  
Vol 8 (1) ◽  
pp. 107-116
Author(s):  
Zbigniew Suchorab ◽  
Danuta Barnat-Hunek
Keyword(s):  
Heat Conductivity ◽  
Building Materials ◽  
Winter Season ◽  
Time Domain Reflectometry ◽  
Heat Conductivity Coefficient ◽  
Water Desorption ◽  
Concrete Building ◽  
Absorbing Material ◽  
Aerated Concrete ◽  
Comfort Parameters

The article is sacrificed to the aerated concrete building barriers moisture phenomenon. Water, which increases heat conductivity of building materials is the reason of the increased heat loses during the winter season. The result of this phenomenon is the decrease of indoor heat comfort parameters. Aerated concrete is a strongly water absorbing material with elongated time of water desorption. Capillary-porous structure of the described medium makes is highly prone to water influence what is the reason of the detailed analysis of heat conductivity coefficient in relation to moisture. In this article it is analyzed and compared the influence of moisture changes on heat parameters of the aerated concrete with the bulk densities of 400 and 600 kg/m3 using the reflectometric techniques TDR (Time Domain Reflectometry).

Size, physical properties, and orbital evolution of the comet Hale-Bopp (C/1995 O1) nucleus

1999 ◽  
Vol 173 ◽  
pp. 371-374
Author(s):  
K.I. Churyumov ◽  
V.G. Kruchynenko ◽  
R.V. Makarchuk
Keyword(s):  
Energy Balance ◽  
Physical Properties ◽  
Heat Conductivity ◽  
Orbital Evolution ◽  
The Sun ◽  
Orbital Elements ◽  
Heat Conductivity Coefficient ◽  
Sublimation Rate ◽  
The Moment ◽  
Comet Halley

AbstractThe equation of the energy balance for the comet Hale-Bopp nucleus is analyzed for the moment when the comet passed perihelion and the sublimation rate (for water) was 1031molecules s−1≈ 3 × 105kgs−1. The minimal value of the nucleus radiusRequ(for γ = 1.0, i.e. the total surface sublimation) equals 14.6 km; for γ = 0.2 (the comet Halley nucleus had approximately this γ value)Requ= 33 km; the thickness of the mineral crust equals ≈ 10−2m for the heat conductivity coefficient ƛ ≈ 0.2 Jm−1s−1K−1. The results of calculations of the orbital elements evolution of the comet Hale-Bopp during one rotation around the Sun show that the comet will not collide with Jupiter (both passages near Jupiter will take place at distances more than 4 AU).

The effect of the temperature dependence of the heat conductivity on the physical laws of the bulk synthesis of a composite

2021 ◽  
pp. 33-39
Author(s):  
N.V. Bukrina ◽  
Keyword(s):  
Temperature Dependence ◽  
Heat Conductivity ◽  
Chemical Compounds ◽  
Heat Conductivity Coefficient ◽  
Temperature Dependent ◽  
High Temperature Synthesis ◽  
Formal Kinetic ◽  
Cylindrical Mold ◽  
Comparison Of The Results ◽  
Physical Laws

Two-dimensional model of high-temperature synthesis of chemical compounds and alloys in a dynamic thermal explosion mode when a powder compact is heated in a steel cylindrical mold by an induction heat source are proposed. The complex of chemical reactions is described by a total reaction with effective formal kinetic parameters. The kinetic law takes into account strong retardation of the reaction by the layer of the synthesized product that prevents the interaction of the reagents. The model makes it possible to investigate the macroscopic physical laws of the synthesis of a composite with a change in the heating rate and reactor dimensions. It is made a comparison of the results obtained for a constant heat conductivity coefficient and a temperature-dependent heat conductivity coefficient. It is revealed that taking into account the temperature dependence of the heat conductivity coefficient can lead to a numerical change in the ignition delay time and to a qualitatively different temperature distribution in the reactor bulk.

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