Heat Modeling of the Catenary’s Contact Wire During the Electrical Power Supply of Trains in Station

2014 ◽  
Author(s):  
Thomas Bausseron ◽  
Philippe Baucour ◽  
Raynal Glises ◽  
Sylvain Verschelde ◽  
Didier Chamagne
Keyword(s):  
Experimental Study ◽  
Heat Flux ◽  
Heat Conduction ◽  
Heat Exchange ◽  
Numerical Model ◽  
Thermal Resistance ◽  
Power Supply ◽  
Electrical Power ◽  
Contact Wire ◽  
Interface Heat

The overheating problem of the railroad catenary at the contact with the pantograph when the train is stopped and electrically fed is responsible of many incidents. This paper describes an experimental study and a numerical model of a catenary/pantograph system used during the preconditioning of the train. Several incidents of wire breakage have highlighted the importance of the catenary/pantograph heating problem, in those incidents the contact wire had melted and broke itself. The experimental setups consists of estimating the contact’s thermal resistance and area in order to calculate which part of the interface heat flux go throught the catenary’s contact wire and which part go throught the pantograph’s collector strip. The numerical model is based on several phenomena as heat conduction into the wires, heat exchange with ambiance through convection, Joule effects and heat flux from the interface.

Heat Conduction Rectification in Nanostructure With Step Change in Cross-Section

2010 ◽  
Author(s):  
Xingang Liang ◽  
Bao Yue
Keyword(s):  
Heat Flux ◽  
Heat Conduction ◽  
Thermal Resistance ◽  
Cross Section ◽  
Temperature Difference ◽  
Flow Direction ◽  
Step Change ◽  
Dynamics Simulation ◽  
Rectification Effect ◽  
Thick Part

Heat conduction rectifier is attracting more attention due to its potential application to process thermal currents independently and convert them into electronic signals. This work reports an investigation by molecular dynamics simulation on the heat conduction rectification effect in the nanostructure whose cross-section have step change along the heat flux. It is found that thermal resistance is different with reversed heat flux direction, which is called the heat conduction rectification. The heat conduction rectification depends on the temperature difference. By reducing temperature difference across the nanostructure, the rectification could be reversed. When the temperature difference is small enough, the thermal resistance is larger when the heat flux flows from the thick part to the thin part when the length of the structure is about 10 nm. The larger variation in the cross-section leads the larger difference in the thermal resistance with opposite heat flux. The mechanism of the rectification is discussed. If we take phonons as liquid particles and consider the case of a liquid flowing through a channel with step expansion in cross-section, the flow resistance is less with liquid flowing from the narrow part to the wide part than that in the case with contrary flow direction. In fact, the scattering of phonons at the step face reduces the mean free path of phonon when heat flux conducts from the narrow end to the wide end.

scholarly journals Nonlinear Heat Transport in Superlattices with Mobile Defects

Entropy ◽  
2019 ◽  
Vol 21 (12) ◽  
pp. 1200 ◽  
Author(s):  
David Jou ◽  
Liliana Restuccia
Keyword(s):  
Thermal Conductivity ◽  
Heat Flux ◽  
Heat Conduction ◽  
Thermal Resistance ◽  
Heat Transport ◽  
Concentration Dependence ◽  
Transport Coefficients ◽  
Nonlinear Behavior ◽  
Strongly Nonlinear

We consider heat conduction in a superlattice with mobile defects, which reduce the thermal conductivity of the material. If the defects may be dragged by the heat flux, and if they are stopped at the interfaces of the superlattice, it is seen that the effective thermal resistance of the layers will depend on the heat flux. Thus, the concentration dependence of the transport coefficients plus the mobility of the defects lead to a strongly nonlinear behavior of heat transport, which may be used in some cases as a basis for thermal transistors.

Experimental Measurements of Temperature Distribution in Three Dimensional Stacked Package

2007 ◽  
Author(s):  
Anand Desai ◽  
James Geer ◽  
Bahgat Sammakia
Keyword(s):  
Experimental Study ◽  
Heat Conduction ◽  
Steady State ◽  
Temperature Distribution ◽  
Numerical Model ◽  
Analytical Solution ◽  
Three Dimensional ◽  
Power Input ◽  
Experimental Measurements ◽  
Steady State Heat

This paper presents the results of an experimental study of steady state heat conduction in a three dimensional stack package. The temperatures are measured at different interfaces within the stacked package. Delphi devices are used in the experiment which enables controlled power input and surface temperature of the devices. The experiment is carried out for three different boundary conditions on the package. The power input in varied to study its effects. A numerical model is created to compare to the experimental results. The results are also compared with the analytical solution presented in Desai et al [5] and Geer et al [6]. The results indicate that the experimental, numerical and analytical solutions follow the same trend. The agreement between the experimental and numerical results improves when the lateral losses are taken into account.

Modeling of Interface Heat Flux and Thermal Field of Mold Materials during Gravity Die Casting

2017 ◽  
Vol 895 ◽  
pp. 85-88
Author(s):  
K.V. Sreenivas Rao ◽  
P. Usha ◽  
S. Sanman ◽  
R. Anilchoudary
Keyword(s):  
Boundary Condition ◽  
Heat Flux ◽  
Stainless Steel ◽  
Cast Iron ◽  
Heat Conduction ◽  
Thermal Field ◽  
Temperature Data ◽  
Temperature History ◽  
Steel Mold ◽  
Interface Heat

One of the key controllable and influential factors to obtain a casting simulation, representative of reality, is the choice of boundary condition. The thermal boundary condition to be specified at the metal-mold interface must account for complex heat transfer phenomena associated with solidifying casting. The present study aims at estimating the heat flux at the interface of the mold and the solidifying metal by Inverse Heat Conduction Problem (IHCP) approach. Solidification studies were conducted on casting of aluminum reinforced with boron carbide composite. Copper, cast iron and stainless steel were used as mold materials. The temperature data of the mold was recorded from the beginning to end of solidification using k-type thermocouples connected to temperature data logger. This time-temperature history was used as input to the IHCP algorithm to simulate the interface heat flux and thermal field of the mold. The results indicate that the interface heat flux is highly transient and varies with the variation in the thermo-physical properties of the mold materials. The study also demonstrates that heat conduction is one dimensional in copper mold and two dimensional in cast iron and stainless steel mold during phase change.

scholarly journals Numerical Simulation of a Thermosyphon Radiator Used in Electronic Devices

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Liang Ding ◽  
Wei Wang ◽  
Bingrui Li ◽  
Yong Shuai ◽  
Bingxi Li
Keyword(s):  
Heat Flux ◽  
Numerical Model ◽  
Thermal Resistance ◽  
Wall Temperature ◽  
Thermal Load ◽  
Heat Dissipation ◽  
Electronic Devices ◽  
High Heat ◽  
High Heat Flux ◽  
Load Conditions

The heat dissipation of electronic devices is an important issue. The thermosyphon radiators have high heat dissipation performance, so they are gradually widely used in electronic devices. In this study, a numerical model of the thermosyphon is established. It is observed that simulated temperatures agree well with experimental data in the literature with a relative error no more than 4%. After the numerical model is validated, it is used in the simulation of the thermosyphon radiator. The wall temperature of the condensing section under different thermal load conditions is compared, and the thermal resistance of the condensing section is analyzed. The results show that with the increase of heating and condensing heat flux, the wall temperature fluctuation of the condensing section increases, but very small just about 5K, 6K, 7K, and 9K, respectively. The thermal resistance of the condensing section decreases, indicating that the thermosyphon radiator has a better performance under high heat flux conditions.

scholarly journals Heat transfer in a centrifugal vortex tube

2021 ◽  
Vol 2119 (1) ◽  
pp. 012065
Author(s):  
E U Gorelikov ◽  
I V Naumov ◽  
M A Tsoy ◽  
V N Shtern
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Heat Flux ◽  
Heat Exchange ◽  
Vortex Tube ◽  
Colorimetric Method ◽  
Rotating Disk ◽  
Thermocapillary Effect ◽  
Immiscible Liquids ◽  
Vortex Apparatus

Abstract The results of an experimental study of the heat flux in a model of a centrifugal vortex apparatus with a lower rotating disk are presented. An experiment considered three cases at a distance between the disks H=R/2 and H=R: “water”, “water-air”, and “water-oil”. Using the colorimetric method, the dependence of the heat flux on Reynolds is shown. The case “water-air” was chosen to evaluate the contribution to heat exchange from the thermocapillary effect (Marangoni) at high Re. For the case of two immiscible liquids of different densities (water-oil), the effect of “centrifugal levitation” is found.

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