scholarly journals Three-Dimensional Reconstruction of Thermal Volumetric Sources from Surface Temperature Fields Measured by Infrared Thermography

2019 ◽  
Vol 9 (24) ◽  
pp. 5464 ◽  
Author(s):  
Marie-Marthe Groz ◽  
Emmanuelle Abisset-Chavanne ◽  
Anissa Meziane ◽  
Alain Sommier ◽  
Christophe Pradère
Keyword(s):  
Temperature Field ◽  
Surface Temperature ◽  
Infrared Thermography ◽  
Three Dimensional ◽  
Ultrasonic Waves ◽  
Temperature Fields ◽  
Heat Sources ◽  
Destructive Testing ◽  
Dimensional Reconstruction ◽  
Energy Conversion Systems

Non-destructive testing (NDT) of materials and structures is a very important industrial issue in the fields of transport, aeronautics and space as well as in the medical domain. Active infrared thermography is an NDT method that consists of providing an external excitation to cause an elevation of the temperature field in the material, consequently allowing evaluation of the resulting temperature field at the surface. However, thermal exciters that are used (flash lamps, halogen, lasers) act only on the surface of the sample. On the other hand, several energy conversion systems can lead to the generation of volumetric sources; the phenomena of thermo-acoustics, thermo-induction, thermomechanics or thermochemistry can be cited. For instance, ultrasonic waves can generate volumetric heat sources if the material is viscoelastic or if there is a defect. The reconstruction of these sources is the initial process for the quantification of parameters responsible for the heating. Characterizing a heat source means reconstructing its geometry and the supplied power. Identification of volumetric heat sources from surface temperature fields is a mathematically ill-posed problem. The main cause of the issue is the diffusive nature of the temperature. In this work, 3D reconstruction of the volumetric heat sources from the resulting surface temperature field, measured by infrared thermography, is studied. An analysis of the physical problem enables specifying the limits of the reconstruction. In particular, a criterion on the achievable spatial resolution is defined, and a reconstruction limitation for in-depth sources is highlighted.

scholarly journals Modeling the Temperature Field in the Ground with an Installed Slinky-Coil Heat Exchanger

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 4010
Author(s):  
Monika Gwadera ◽  
Krzysztof Kupiec
Keyword(s):  
Temperature Field ◽  
Heat Exchanger ◽  
Surface Temperature ◽  
Ground Surface ◽  
Heat Sources ◽  
Ground Surface Temperature ◽  
Coil Heat Exchanger ◽  
The Relationship ◽  
Temperature Responses ◽  
Coil Heat

In order to find the temperature field in the ground with a heat exchanger, it is necessary to determine temperature responses of the ground caused by heat sources and the influence of the environment. To determine the latter, a new model of heat transfer in the ground under natural conditions was developed. The heat flux of the evaporation of moisture from the ground was described by the relationship taking into account the annual amount of rainfall. The analytical solution for the equations of this model is presented. Under the conditions for which the calculations were performed, the following data were obtained: the average ground surface temperature Tsm = 10.67 °C, the ground surface temperature amplitude As = 13.88 K, and the phase angle Ps = 0.202 rad. This method makes it possible to easily determine the undisturbed ground temperature at any depth and at any time. This solution was used to find the temperature field in the ground with an installed slinky-coil heat exchanger that consisted of 63 coils. The results of calculations according to the presented model were compared with the results of measurements from the literature. The 3D model for the ground with an installed heat exchanger enables the analysis of the influence of miscellaneous parameters of the process of extracting or supplying heat from/to the ground on its temperature field.

scholarly journals Impact of Tunnel Temperature Variations on Surrounding Rocks in Cold Regions

2019 ◽  
Author(s):  
Qingyang Yu ◽  
Chao Zhang ◽  
Zhenxue Dai ◽  
Chao Du ◽  
Mohamad Reza Soltanian ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Temperature Field ◽  
Temperature Distribution ◽  
Three Dimensional ◽  
Temperature Fields ◽  
Insulation Layer ◽  
Cold Regions ◽  
Ambient Temperatures ◽  
Temperature Conditions ◽  
Layer Control

Temperature is an important factor in designing and maintaining tunnels, especially in cold regions. We present three-dimensional numerical simulations of tunnel temperature fields at different temperature conditions. We study the tunnel temperature field in two different conditions with relatively low and high ambient temperatures representing winter and summer of northeast China. We specifically study how these temperature conditions affect tunnel temperature and its migration to surrounding rocks. We show how placing an insulation layer could affect the temperature distribution within and around tunnels. Our results show that the temperature field without using an insulation layer is closer to the air temperature in the tunnel, and that the insulation layer has shielding effects and could plays an important role in preventing temperature migration to surrounding rocks. We further analyzed how thermal conductivity and thickness of insulation layer control the temperature distribution. The thermal conductivity and thickness of insulation layer only affect the temperature of the surrounding rocks which are located at distances below ~20 m from the lining.

Numerical Analysis on the Temperature Field in Laser-Plasma Hybrid Welding of an Aluminum Alloy

2008 ◽  
Vol 580-582 ◽  
pp. 279-282
Author(s):  
Zhi Ning Li ◽  
Bao Hua Chang ◽  
Dong Du ◽  
Hua Zhang
Keyword(s):  
Heat Transfer ◽  
Aluminum Alloy ◽  
Laser Plasma ◽  
Three Dimensional ◽  
Temperature Fields ◽  
Transfer Model ◽  
Heat Sources ◽  
Hybrid Welding ◽  
Plasma Arc ◽  
Simulation Results

A three dimensional heat transfer model on laser-plasma hybrid welding has been proposed, that takes into account the interaction between laser beam and plasma arc. Through FEM computation, the temperature fields were computed and analyzed for an Al-Li alloy during laserplasma hybrid welding with different distances between the two heat sources. The simulation results are in agreement with the experimental results.

scholarly journals Stationary problem of heat conductivity for complex-shape multilayer plates

2019 ◽  
Keyword(s):  
Complex Shape ◽  
Heat Conduction Problem ◽  
Three Dimensional ◽  
Convective Heat Exchange ◽  
Stationary Problem ◽  
Temperature Fields ◽  
Heat Sources ◽  
Immersion Method ◽  
Stationary Heat Conduction ◽  
Square Plate

A method for calculating stationary temperature fields in a complex-shape multilayer plate when it is heated with film heat sources is proposed. Convective heat exchange takes place on the outer surfaces of the plate. The solution of the stationary heat conduction problem is obtained for a three-dimensional formulation based on the immersion method. A comparative analysis of the temperature distribution along the thickness of a square plate with the results obtained by finite element method has been carried out. As an example, the problem of stationary thermal conductivity for a five-layer glazing element of a vehicle when heated with a film heat source has been solved.

Three-Dimensional Analytical Temperature Field Around the Welding Cavity Produced by a Moving Distributed High-Intensity Beam

1993 ◽  
Vol 115 (4) ◽  
pp. 848-856 ◽  
Author(s):  
P. S. Wei ◽  
M. D. Shian
Keyword(s):  
Temperature Field ◽  
Power Density ◽  
High Power ◽  
Three Dimensional ◽  
Second Law Of Thermodynamics ◽  
Temperature Fields ◽  
Momentum Balance ◽  
High Power Density ◽  
Depth Of Penetration ◽  
Confluent Hypergeometric Functions

An analytical solution for the three-dimensional temperature field in the liquid and heat-affected zones around a welding cavity produced by a moving distributed low- or high-power-density-beam is provided. The incident energy rate distribution is assumed to be Gaussian and the cavity is idealized by a paraboloid of revolution in workpieces of infinite, semi-infinite, or finite thicknesses. The present study finds that temperature fields can be described by the Laguerre and confluent hypergeometric functions. By satisfying a momentum balance at the cavity base and utilizing a consequence of the second law of thermodynamics, the depth of penetration is uniquely determined. The results show that the predicted depths and temperatures of the cavity agree with available experimental data. Some crucial factors affecting the transition from low- to high-power-density-beam welding are presented.

Analysis of Transient Heat Conduction in Complex Shaped Composite Materials

1988 ◽  
Vol 110 (2) ◽  
pp. 110-112 ◽  
Author(s):  
Seiichi Nomura ◽  
A. Haji-Sheikh
Keyword(s):  
Temperature Field ◽  
Heat Conduction ◽  
Composite Materials ◽  
Analytical Procedure ◽  
Three Dimensional ◽  
Transient Heat Conduction ◽  
Temperature Fields ◽  
Finite Region ◽  
Symbolic Algebra ◽  
The Galerkin Method

This paper addresses a generalized analytical procedure for transient heat conduction in composite materials of two- and three-dimensional finite region. The Galerkin method is employed to obtain temperature field in closed form with the utilization of symbolic algebra software such as REDUCE or MACSYMA. It is found from illustrative examples that the proposed method yields accurate and effective predictions of temperature fields for which purely numerical methods such as finite element or finite difference are not suitable.

On the Use of Point Source Solutions for Forced Air Cooling of Electronic Components—Part I: Thermal Wake Models for Rectangular Heat Sources

2003 ◽  
Vol 125 (2) ◽  
pp. 226-234 ◽  
Author(s):  
Alfonso Ortega ◽  
Shankar Ramanathan
Keyword(s):  
Temperature Field ◽  
Point Source ◽  
Three Dimensional ◽  
Air Cooling ◽  
Heat Sources ◽  
Multiple Sources ◽  
One Dimensional ◽  
Forced Air ◽  
The Individual ◽  
Thermal Wake

Analytical solutions are presented for the temperature field that arises from the application of a source of heat on an adiabatic plate or board when the fluid is represented as a uniform flow with an effective turbulent diffusivity, i.e., the so-called UFED flow model. Solutions are summarized for a point source, a one-dimensional strip source, and a rectangular source of heat. The ability to superpose the individual kernel solutions to obtain the temperature field due to multiple sources is demonstrated. The point source solution reveals that the N−1 law commonly observed for the centerline thermal wake decay for three-dimensional arrays is predicted by the point source solution for the UFED model. Examination of the solution for rectangular sources shows that the thermal wake approaches the point source behavior downstream from the source, suggesting a new scaling for the far thermal wake based on the total component power and a length scale given by ε/U. The new scaling successfully collapses the thermal wake for several sizes of components and provides a fundamental basis for experimental observations previously made for arrays of three-dimensional components.

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