Thermal Field Distribution Research Articles

РОЗПОДІЛ МАГНІТНОГО І ТЕПЛОВОГО ПОЛІВ ТА ВТРАТИ ПОТУЖНОСТІ В ЕЛЕКТРОМАГНІТНОМУ ЕКРАНІ ПІДЗЕМНОЇ ДВОКОЛОВОЇ КАБЕЛЬНОЇ ЛІНІЇ

In the article, the magnetic and thermal field distributions generated by underground two-circuit extra-high voltage power cable line in the environment, particularly near the cables and flat aluminum shield, which is located at a different distance from the cables and has different thicknesses, are analyzed. The unique features of the magnetic field and temperature distributions inside the shield are computed and studied. For the cases under consideration, the Joule losses in the external shield do not exceed 3% of the losses in the cables. The primary electromagnetic characteristics are compared for the aluminum shield (shielding efficiency is 1,94) and the shield with lower conductivity (shielding efficiency is equal to 1,2). As shown, the thicker shield helps to increase the ampacity of the cable line owing to lower heating. The actual operating current of the cable line under consideration depends on the distance of the shield from the cables owing to the relation between their maximum temperature and this distance. Ref. 15, fig. 7, table.

Distribution of temperature field in phantom of hand with microwave radiation

The present work presents the results of phantom of human hand simulation with the dielectric properties, very similar with human tissues properties. The simulation was conducted with using “CST Studio” software. The phantom was made by a “papier-mâché” method. The thermal field distribution was measured twice: for the simulation of phantom in “CST Studio” software, and for the phantom filled with dispersed meat of pork, the power was 2.45 GHz. The heating profile of certain points on phantom, including fingers, has been studied. It is shown that the heating profile of fingers zone is different from heating profile of wrist and forearm. The obtained experimental data have shown the possibility of using microwave radiation for deep cold injuries treatment.

Investigation of the Thermal Field on Solid Propellant Grain with Cracks by Moving Particle Semi‐Implicit Method

AbstractUnder extreme operating conditions in gun barrel like high pressure and high temperature, fracture or cracks may propagate on solid propellant grains and become a threat to firing safety. The existence and the propagation of cracks will affect the combustion efficiency of solid propellant, and the thermal field of grain with cracks needs to be simulated. In this paper, we applied one of the Particle Methods, Moving Particle Semi‐implicit Method, to the investigation of the thermal field on solid propellant grain with cracks. An improved MPS operator is first introduced and the treatment on crack boundary including Robin boundary condition is also presented. The application of particle method to heat conduction is verified by the simulation of a seven‐perforated propellant grain under fixed temperature. Then, with different properties of cracks like the length, the number and the boundary conditions, the thermal field distribution of propellant grain and heat transfer efficiency are compared and analyzed.

Research on Multiphysics Coupling Relationship for the IPT System in Seawater Environment

Wireless charging in the marine environment has problems such as high loss and low efficiency. In order to solve these problems, based on the wireless power transmission technology in the seawater environment, this paper studies the multi-physical field coupling relationship of the underwater IPT system. Through researching on the law of mutual influence and interaction between the fields, the relationship between the physical fields is established. The software is used to establish a system simulation model, the dataset is solved and analyzed to get the distribution of electric field, magnetic field, thermal field, and flow field, which provides a theoretical basis for the model and optimization of the IPT system in the seawater.

Computer simulation of temperature fields in the Cr (film)-Zr (substrate) system during pulsed electron-beam irradiation

The paper presents the results of numerical simulation of the distribution of thermal fields during the formation of Cr-Zr surface alloy using a pulsed low-energy high-current electron beam (LEHCEB). The melting thresholds of the Cr-Zr system for different thicknesses of Cr films were calculated. The melting threshold of the Cr-Zr system increases linearly with increasing Cr film thickness. A linear regression dependency model of the melting threshold on the film thickness is proposed. Evaporation thresholds of the Cr-Zr system for different thicknesses of Cr films were calculated. The evaporation threshold of the Cr-Zr system increases linearly with increasing Cr film thickness. A linear regression dependency model of the evaporation threshold on the film thickness is proposed. The value of the LEHCEB energy density at which the lifetime of the film and substrate are equal is calculated. This value is a maximum value for the effective formation of Cr-Zr. A model of the LEHCEB energy density, at which the lifetime of the film and the substrate are equal, in the form of a third-degree polynomial is proposed.

Simulation calculation and comparative analysis of three-dimensional temperature field of ultra high voltage through wall bushing under different current carrying capacity

As the key equipment of UHV transmission and transformation line, UHV bushing needs to carry the ultra-high voltage and large current of UHV power system at the same time. When the operating temperature of UHV bushing is too high, the operation failure rate will increase significantly, which will affect the stability and safety of UHV transmission line. Therefore, it is particularly important to analyze the temperature field characteristics of UHV bushing. This paper takes UHV bushing as the research object. The finite element software is used to calculate the electro thermal coupling. The three-dimensional thermal field distribution characteristics of UHV bushing are simulated and analyzed. This paper analyzes the influence of eddy current on the temperature distribution of UHV bushing under operation condition, and discusses the influence degree of eddy current on the temperature distribution of bushing, which provides an important basis for the temperature distribution, structure improvement and operation maintenance of bushing.

Design of internal heat transport intensifier for metal hydride storage tank

The present article deals with potential improvement of heat removal from the centre of a metal hydride tank towards the tank’s periphery while using passive heat transfer modules. Passive cooling elements are used in order to improve heat removal from the centre of a tank towards its peripheral parts. This increases the homogeneity of the thermal field in a tank’s cross-section, which is perpendicular to the longitudinal axis. Moreover, the use of such elements improves the kinetics of hydrogen absorption into an alloy, in particular by prolonging the time to an equilibrium temperature of the alloy for a particular equilibrium pressure, which may shorten the time to a tank being 100% filled with hydrogen. The article describes four different designs of internal heat transfer intensifiers, which are aimed at improving the thermal field distribution inside the tank and their theoretical impact on the thermal field, which was examined using Ansys CFX software.

Thermal field distribution investigation and simulation of silver paste heating fabric by screen printing based on Joule heating effect

Thermal field distribution investigation and simulation of silver paste heating fabric by screen printing based on Joule heating effect

An improved thermo-parameters method for dynamic shakedown analysis of railway subgrade

To ensure the safety and stability of train operation, a reasonable evaluation of long-term durability of railway subgrade subjected to large number of cyclic train loads is necessary. With the concept of controlling safety margins against excessive inelastic deformation, shakedown theory provides an effective approach for the analysis of long-term performance of geotechnical structures. In this paper, an improved thermo-parameters method (TPM) is proposed to carry out dynamic shakedown analysis on the railway subgrade. Mathematically, the method is formulated as an optimization problem, in which the objective function is the dynamic shakedown limit and variables are the shakedown residual stresses defined through the distribution of hypothetical thermal stress field and further described by the Non-Uniform Rational B-Splines (NURBS) surface. The presented solution procedure was incorporated to the finite element (FE) model and numerical examples were presented to demonstrate its effectiveness for different cases. An in-situ test conducted in a fill section of railway subgrade was used for numerical modeling and further result validation. The results indicated that the dynamic shakedown limits varied with the loading frequency and showed smaller values than the quasi-static shakedown limit, especially at the natural frequency of structure. The current findings may be beneficial to the further understanding of the long-term durability and stability of subgrade under dynamic loading, and provide useful information for the shakedown design of the railway subgrade.

Temperature distribution in the phantom of limb in the microwave chamber with linear source of radiation

The paper presents results of temperature distribution in the phantom of limb under the microwave radiation. The authors have developed automated apparatus based on linear positioner and temperature detector. The apparatus is aimed at measuring the distribution of thermal field in phantom of a human hand. It was shown that impulse microwave radiation with a power of 40W during 6 minutes leads to uniform heating along longitudinal axis of phantom. The apparatus “SMVi-200” was used as a microwave source being normally applied for hypothermia treatment.

Simulation of Thermal and Electric Field Distribution in Packaged Sausages Heated in a Stationary Versus a Rotating Microwave Oven.

The microwave oven has become a standard appliance to reheat or cook meals in households and convenience stores. However, the main problem of microwave heating is the non-uniform temperature distribution, which may affect food quality and health safety. A three-dimensional mathematical model was developed to simulate the temperature distribution of four ready-to-eat sausages in a plastic package in a stationary versus a rotating microwave oven, and the model was validated experimentally. COMSOL software was applied to predict sausage temperatures at different orientations for the stationary microwave model, whereas COMSOL and COMSOL in combination with MATLAB software were used for a rotating microwave model. A sausage orientation at 135° with the waveguide was similar to that using the rotating microwave model regarding uniform thermal and electric field distributions. Both rotating models provided good agreement between the predicted and actual values and had greater precision than the stationary model. In addition, the computational time using COMSOL in combination with MATLAB was reduced by 60% compared to COMSOL alone. Consequently, the models could assist food producers and associations in designing packaging materials to prevent leakage of the packaging compound, developing new products and applications to improve product heating uniformity, and reducing the cost and time of the research and development stage.

Study on the thermal field distribution of cholangiocarcinoma model by magnetic fluid hyperthermia

Cholangiocarcinoma is a highly malignant tumor. It is not sensitive to radiotherapy and chemotherapy and has a poor prognosis. At present, there is no effective treatment. As a new method for treating cancer, magnetic fluid hyperthermia has been clinically applied to a variety of cancers in recent years. This article introduces it to the cholangiocarcinoma model and systematically studies the effect of magnetic fluid hyperthermia on cholangiocarcinoma. Starting from the theory of magnetic fluid heating, the electromagnetic and heat transfer models were constructed in the finite element simulation software COMSOL using the Pennes biological heat transfer equation. The Helmholtz coil was used as an alternating magnetic field generating device. The relationship between the magnetic fluid-related properties and the heating power was analyzed according to Rosensweig's theory. After the multiphysics coupling simulation was performed, the electromagnetic field and thermal field distribution in the hyperthermia region were obtained. The results showed that the magnetic field distribution in the treatment area was uniform, and the thermal field distribution met the requirements of hyperthermia. After the magnetic fluid injection, the cholangiocarcinoma tissue warmed up rapidly, and the temperature of tumor tissues could reach above 42 °C, but the surrounding healthy tissues did not heat up significantly. At the same time, it was verified that the large blood vessels around the bile duct, the overflow of the magnetic fluid, and the eddy current heat had little effect on thermotherapy. The results of this article can provide a reference for the clinical application of magnetic fluid hyperthermia for cholangiocarcinoma.

Distribution of Temperature and Strength in the Central Andean Lithosphere and Its Relationship to Seismicity and Active Deformation

AbstractWe present three‐dimensional (3D) models of the present‐day steady‐state conductive thermal field and strength distribution in the lithosphere beneath the Central Andes. Our primary objective was to investigate the influence that the structure of the Central Andean lithosphere has on its thermal and rheological state, and the relationship between the latter and the active deformation in the region. We used our previous data‐driven and gravity‐constrained 3D density model as starting point for the calculations. We first assigned lithology‐derived thermal and rheological properties to the different divisions of the density model and defined temperature boundary conditions. We then calculated the 3D steady‐state conductive thermal field and the maximum differential stresses for both brittle and ductile behaviors. We find that the thickness and composition of the crust are the main factors affecting the modeled thermal field, and consequently also the strength distribution. The orogen is characterized by a thick felsic crust with elevated temperatures and a low integrated strength, whereas the foreland and forearc are underlain by a more mafic and thinner crust with lower temperatures and a higher integrated strength. We find that most of the intraplate deformation coincides spatially with the steepest strength gradients and suggest that the high potential energy of the orogen together with the presence of rheological lateral heterogeneities produce high compressional stresses and strong strain localization along the margins of the orogen. We interpret earthquakes within the modeled ductile field to be related to the weakening effect of long‐lived faults and/or the presence of seismic asperities.

Study of Oil/Pressboard Creeping Discharges under Divergent AC Voltage—Part 2: Internal Treeing and Surface Tracking

This paper presents both an experimental study and a theoretical discussion on the relevant faults resulting from progressive creeping discharge. Pressboard ageing, voltage amplitude, and pressboard type are configured to generate the faults under divergent creeping stresses. The fault progression is recorded by high-resolution camera, partial discharge (PD) device, and optic-fiber thermometer. The damaged pressboards are scrutinized by microscopy and image-processing techniques, and gas chromatography is used to analyze the gas compositions. The progression of internal treeing shows distinct stages of different interface phenomena, such as spark discharge, white marks, and bubbling effect, as well as varying discharge patterns. In contrast, the progression of surface tracking is a simple but hardly noticeable process due to the PD disappearance. The internal carbonization channels are believed the fundamental causes of the interface phenomena pertinent to internal treeing. A theoretical model is proposed to expound the development of the internal carbonization channels, which considers the charge emission, the pressboard pyrolysis, and the percolation theory. The failure mode of internal treeing is schematically illustrated using a four-phase model, and the effects of thermal ageing and field distribution on surface tracking are discussed. Lastly, a detailed comparison is made between internal treeing and surface tracking in terms of the occurrence condition, initiation mechanism, growth driver, and growth characteristics.

Analytical method of calculation of thermal fields of foundry cores

The aim of the work is to create on the basis of the analysis of thermophysical parameters and regularities of mathematical methods, which allows to calculate the distribution of thermal fields in molds and rods using a system of analytical formulas. The method of calculating thermal fields in foundry molds and rods developed and presented in this publication is based on the finite difference method. Much attention is paid to the calculations of the dynamics of changes in the surface temperatures of the casting rod and its center. The article shows that the basis for the correct calculation of the thermal field of the rod is to establish the change in surface temperature in the first few seconds after the start of contact with the melt. All currently available methods do not take into account this change in temperature. A new concept is introduced - the period of thermal inertia of the rod. This is the period of time during which its surface temperature rises from the initial value (ambient temperature) to a value corresponding to the surface temperature of the casting. The period of thermal inertia depends exclusively on the thermophysical properties of the rod. To calculate the temperature change in the center of the casting rod, a modified method of S. Schwartz was used: instead of the constant contact temperature of the "casting-rod" in the formula takes into account the previously estab- ?ished dynamics of changes in this temperature. The thermal fields of cylindrical foundry rods with diameters of 50 mm and 16 mm were calculated according to the created mathematical method. A comparison of the results of calculations according to the developed method and with the use of existing software is presented. The difference in design temperatures is 100 oC and more. The difference in determining the thermal fields of a smaller diameter rod is particularly noticeable, which is due to the rapid dynamics of changes in the surface temperature of the casting, which is currently not taken into account by current methods. The developed mathematical technique can be offered as a theoretical basis for refining applied computer programs for foundry production.

Experimental Study on Heat Distribution of High-Voltage Cable Terminals under Operating Conditions

The insulation failure of the outdoor terminal of the high-voltage cross-linked polyethylene (XLPE) cable has a significant impact on the operation stability of the power grid. Effective evaluation of its thermal state is of great significance to predicting its insulation failure. The paper uses infrared thermal imaging to analyse the thermal field distribution characteristics of the outdoor terminal surface under different ambient temperatures. Test results, theoretical calculations and simulation results all show that the thermal steady-state temperature of the inner and outer layers of the sheath shows a non-linear increase with the increase of the current carrying capacity of the cable, which verifies the correctness of the model, so this model can be used to predict And analyse the temperature distribution of the actual 10kV cable cold shrink terminal at the thermal steady state.

Analytical method of calculation of thermal fields of cast parts during crystallization

The aim of the work is to create a mathematical method that allows to calculate the distribution of thermal fields in cast parts during crystallization using a system of analytical formulas. During the calculations, a combination of known analytical formulas GF was used. Balandin, AY Weinik, S. Schwartz with their own original mathematical solutions created on the basis of the analysis of thermophysical processes in castings in the process of their crystallization. Computer simulation of thermal fields using the LVMFlow program was used to compare the results. According to the created mathematical method, examples of calculation of thermal fields for two castings made of steel 25L of hollow cylindrical shape, the wall thickness of which is 100 mm and 4 mm, respectively, are given. Calculations were performed for the conditions of crystallization of castings in a single sand form. The comparison of results of calculations by the developed method and with use of the existing software is presented. For the first time, based on our own mathematical and thermophysical developments, a comprehensive calculation method for determining the thermal field of the casting during crystallization and cooling was developed. casting. The technique is expressed in a number of analytical formulas, each of which describes a specific thermal process that occurs in the casting. This takes into account the features of the casting configuration. The created complex method of calculation of thermal fields of cast parts is a mathematical basis for determining the thermal fields of molds and rods, which allows to predict their properties and select the optimal molding materials. The created technique can also be offered as a mathematical basis for refining applied computer programs for foundry production. CASTING, TEMPERATURE, THERMAL FIELD, COOLING DYNAMICS, COOLING DURATION, MATHEMATICAL LAW, COLORING FRONT, CALCULATION

A digital control system designed for ore thermal furnaces producing metallurgical silicon

This paper considers the key control issues related to non-adjustable parameters in the production of metallurgical silicon in ore thermal furnaces. A series of experiments has been conducted to confirm the possibility of introducing the electrode off-position control. Thus, additional control parameters were introduced in the process control system. The electrode positioning algorithm was tested and adjusted to minimize electrode bending and reduce the risk of breakage and to minimize end cracking and spalling during restarting in the current production environment. An integrated 3D model of the thermal field distribution has been developed and built that accounts for the charcoal moisture content, the position of the electrodes and the power emitted as the charge gets hot. Substantiation is given to the application of this adaptive adjustment algorithm to control the changing parameters as determined by the process conditions, such as the moisture content of the charge, the position of the electrode, the power mode of the furnace. The authors propose to expand the existing control system by adding a digital module, i.e. due to the integration of electrode off-position signals and the use of the adaptive adjustment algorithm and avoiding using any additional corrective signals. This research was carried out as part of the Governmental Assignment No. 075-03-2020-127/1 for the year of 2020, Project No. FSRW-2020-0014. Subject: A crossdisciplinary approach to the comprehensive exploitation of natural resources and conservation. Area (a 2020 topic): “Comprehensive processing of minerals and man-made materials and gasification of solid hydrocarbons: A review and concept elaboration”. As greenhouse gases and carbon are produced as a result of electrode destruction, it is proposed to use the method of gasification and dispose of the heat produced.

An effective thermal treatment of toluene-contaminated soil by uniform heating from microwave coupled infrared radiation (MCIR)

Thermal treatment technologies are generally very effective for the remediation of soils contaminated. For the traditional thermal treatment method of contaminated soil, the heating method from the outside to the inside will inevitably cause a waste of energy, and it may be expensive due to the energy costs. Therefore, it is necessary to find a new heating technology to improve the thermal treatment. In this study, a novel microwave coupled infrared radiation (MCIR) technology was used to achieve uniform heating treatment of contaminated soil. A mathematical model was established and applied to simulate the electric field and temperature induced by microwave radiation and MCIR. The model results showed that MCIR heating produces well uniformity of thermal field distribution. Then, the influence of infrared in the MCIR treatment of soil was investigated by the lab experiment. The lab experimental results indicated that infrared could efficiently improve the microwave treatment of soil. A toluene removal efficiency of 92.8% could be achieved at 500 W microwave coupled with 300 W infrared radiation for 300 s, retaining 9.2% soil moisture. In addition, it exhibited a high cost-benefit. Furthermore, MCIR did not destroy the structure of toluene by infrared spectrum analysis. The results show that this MCIR treatment has the advantages of uniform heating, high efficiency, and low damage, which indicates the application prospect of MCIR in soil remediation.

A spatiotemporal prediction approach for a 3D thermal field from sensor networks

Thermal fields exist widely in engineering systems and are critical for engineering operation, product quality and system safety in many industries. An accurate prediction of thermal field distribution, that is, acquiring any location of interest in a thermal field at the present and future time, is essential to provide useful information for the surveillance, maintenance, and improvement of a system. However, thermal field prediction using data acquired from sensor networks is challenging due to data sparsity and missing data problems. To address this issue, we propose a field spatiotemporal prediction approach based on transfer learning techniques by studying the dynamics of a 3 D thermal field from multiple homogeneous fields. Our model characterizes the spatiotemporal dynamics of the local thermal field variations by considering the spatiotemporal correlation of the fields and harnessing the information from homogeneous fields to acquire an accurate thermal field distribution in the future. A real case study of thermal fields during grain storage is conducted to validate our proposed approach. Grain thermal field prediction results provide a deep insight of grain quality during storage, which is helpful for the manager of grain storage to make further decisions about grain quality control and maintenance.