Wire Temperature Research Articles

Equivalent Test Method for Strong Electromagnetic Field Radiation Effect of EED

The present study proposed the equivalent test method for the strong electromagnetic field radiation of electric explosive devices (EEDs) of the weapon equipment to satisfy the military requirements of the electromagnetic radiation safety test, as well as the evaluation of the electric ignition, the electric initiation ammunition, or missiles. Under stable conditions, the ignition excitation test and the bridge wire temperature increase test were performed to determine the ignition temperature of the EED. As radiated by the strong electromagnetic field, the relationship between the temperature increase of the bridge wire and the electric field intensity of the EED was developed based on the theoretical analysis and the experimental test. Given the ignition temperature of the EED, the radiation field intensity of the EED at 50% ignition was determined. As compared with the 50% ignition field intensity of the EED directly radiated by the strong electromagnetic field, an error less than 1 dB was caused. On that basis, the correctness of the equivalent test method was verified. Accordingly, this method was suggested to act as an effective method and technical means to test and evaluate the electromagnetic radiation safety of ammunition and missiles in unfavorable electromagnetic environments.

Thermal Battery for Electric Vehicles: High-Temperature Heating System for Solid Media Based Thermal Energy Storages

Thermal energy storage systems open up high potentials for improvements in efficiency and flexibility for power plant and industrial applications. Transferring such technologies as basis for thermal management concepts in battery-electric vehicles allow alternative ways for heating the interior and avoid range limitations during cold seasons. The idea of such concepts is to generate heat electrically (power-to-heat) parallel of charging the battery, store it efficiently and discharge heat at a defined temperature level. The successful application of such concepts requires two central prerequisites: higher systemic storage densities compared to today’s battery-powered PTC heaters as well as high charging and discharging powers. A promising approach for both requirements is based on solids as thermal energy storage. These allow during discharging an efficient heat transfer to the gaseous heat transfer medium (air) due to a wide range of geometric configurations with high specific surfaces and during charging high storage densities due to use of ceramic materials suitable for high operating temperatures. However, for such concepts suitable heating systems with small dimensions are needed, allowing an efficient and homogeneous heat transfer to the solid with high charging powers and high heating temperatures. An appropriate technology for this purpose is based on resistance heating wires integrated inside the channel shaped solids. These promise high storage densities due to operating wire temperature of up to 1300 °C and an efficient heat transport via radiation. Such electrically heated storage systems have been known for a long time for stationary applications, e.g., domestic storage heaters, but are new for mobile applications. For evaluation such concepts with regard to systemic storage and power density as well as to identify preferred configurations extensive investigations are necessary. For this purpose, transient models for the relevant heat transport mechanisms and the whole storage system were created. In order to allow time-efficient simulations studies for such an electrical heated storage system, a novel correlation for the effective radiation coefficient based on the Fourier Number was derived. This coefficient includes radiation effects and thermal conduction resistances and enables through its dimensionless parameterization the investigation of the charging process for a wide range of geometrical configurations. Based on application-typical specifications and the derived Fourier based correlation, extensive variation studies regarding the storage system were performed and evaluated with respect to systemic storage densities, heating wire surface loads and dimensions. For a favored design option selected here, maximum systemic storage densities of 201 Wh/kg at maximum heating wire surface loads of 4.6 W/cm2 are achieved showing significant benefits compared to today’s battery powered PTC heaters. Additionally, for proofing and confirming the storage concept, a test rig was erected focusing experimental investigations on the charging process. For a first experimental setup-up including all relevant components, mean temperature-related deviations between the simulative and the experimental results of 4.1% were detected and storage temperatures of up to 870 °C were reached. The systematically performed results confirm the feasibility, high efficiency, thermodynamic synergies with geometric requirements during thermal discharging and the potential of the technology to reach higher systemic storage densities compared to current solutions.

A Method for Determining the Impact of Ambient Temperature on an Electrical Cable during a Fire

Evaluating environmental conditions that trigger fire-fighting equipment is one of the primary design tasks that have to be taken into account when engineering electrical systems supplying such devices. All of the solutions are aimed at, among others, preserving environmental parameters in a building being on fire for an assumed time and at a level enabling safe evacuation. These parameters include temperature, thermal radiation, visibility range, oxygen concentration, and environmental toxicity. This article presents a new mathematical model for heat exchange between the environment and an electric cable under thermal conditions exceeding permissible values for commonly used non-flammable installation cables. The method of analogy between thermal and electrical systems was adopted for modelling heat flow. Determining how the thermal conductivity of the cable and the thermal capacity of a conductor-insulation system can be applied to calculate the wire temperature depending on the heating time t and distance x from the heat source is discussed. Thermal conductivity and capacity were determined based on experimental tests for halogen-free flame-retardant (HFFR) cables with wire cross-sections of 2.5, 4.0, and 6.0 mm2. The conducted experimental tests enable verifying the results calculated by the mathematical model.

A simple numerical method for evaluating heat dissipation from curved wires with periodic applied heating

In many situations, the dual-purpose heater/thermometer wires used in the three-omega method—one of the most precise and sensitive techniques for measuring the thermal conductivity of thin films and interfaces—must include bends and curves to avoid obstructions on the surface of a sample. Although the three-omega analysis assumes that the heating wire is infinitely long and straight, recent experimental work has demonstrated that, in some cases, curved-wire geometries can be used without introducing detectable systematic error. We describe a general numerical method that can be used to calculate the temperature of three-omega heating wires with arbitrary wire geometries. This method provides experimentalists with a simple quantitative procedure for calculating how large the systematic error caused by a particular wire asymmetry will be. We show calculations of two useful cases: a straight wire with a single bend of arbitrary angle and a wire that forms a circle. We find that the amplitude of the in-phase temperature oscillations near a wire that forms a circle differs from the prediction using the analytic straight-line source solution by <12%, provided that the thermal penetration depth is less than ten times the radius of curvature of the wire path. The in-phase temperature amplitude 1.5 wire widths away from a 90° bend in a wire is within 11% of the straight-line source prediction for all penetration depths greater than the wire width. Our calculations indicate that the straight-line source solution breaks down significantly when the wire bend angle is less than 45°.

전차선로 해빙시스템을 위한 발열시험을 통한 전차선 온도상승 특성평가

This paper analyzes the temperature rising characteristics of the deicing catenary system in winter. For the composition of the deicing system, the deicing system is constructed according to the combination of various trolley wires and messenger wires applied at Korea. To compare of temperature rising characteristics, the current distribution ratio between trolley wire and messenger wire are measured and the wire temperature is measured according to the deicing current using a catenary heating test device. In case of current distribution ratio test, the current distribution ratio is measured in 82.1%: 18.9% similar to the theoretical ratio in DC supplying. As a result of temperature rising test, the temperature of Cu 150 ㎟ is increased by 1.26 °C/m at a wind speed of 0.5 m/s and 0.92 °C/m at 2.0 m/s when supplying DC 350 A, And in case of Bz 65 ㎟, when DC 95 A is supplied, the temperature rose at 0.74° C/m at 0.5 m/s, and 0.56 °C/m at 2.0 m/s. In the comparison between the theoretical equation and test result, the difference is at most 0.7 ℃. Therefore, it is confirmed that it would be appropriate to use the theoretical equation in the design of the deicing system.

In Situ Thermometry of Fermionic Cold-Atom Quantum Wires

We study ensembles of fermionic cold-atom quantum wires with tunable transverse mode population and single-wire resolution. From insitu density profiles, we determine the temperature of the atomic wires in the weakly interacting limit and reconstruct the underlying potential landscape. By varying atom number and temperature, we control the occupation of the transverse modes and study the 1D-3D crossover. In the 1D limit, we observe an increase of the reduced temperature T/T_{F} at nearly constant entropy per particle S/Nk_{B}. The ability to probe individual atomic wires insitu paves the way to quantitatively study equilibrium and transport properties of strongly interacting 1D Fermi gases.

Electrical Properties of Superconductive Thick Film Wires Obtained from a Melt Process.

YBaCuO superconductive thick film wires were fabricated by employing a melt process with a peak temperature of 1100 °C. Transition temperature and peak critical current density of these YBaCuO superconductive thick film wires were 90 K and 3.5 × 10⁴ A/cm², respectively. Their magnetic lev-itation force measured at a temperature of 77 K with a permanent magnet was 65.45 N during magnetic cooling. The repulsion force in the case of field cooling was 10.12 N. A permanent magnet with surface magnetism of 5.25 kG was used to cool down superconductive specimens, from which magnetic force of 15.62% of peak magnetic field was trapped. A single crystal YBaCuO superconductive thick film wire was obtained after coating powders of raw materials from a melt process employed for the fabrication of YBaCuO superconductive thick film wire.

Measurement of thermal conductivity and thermal diffusivity of one-dimensional-system material by scanning electron microscopy and infrared thermography

A novel measurement system consisting of scanning electron microscopy and infrared (IR) thermography has been constructed to measure the thermal conductivity and the thermal diffusivity on a micro-/nanometer scale. In this study, we measured them for a stainless-steel wire with a diameter of 50 μm to demonstrate the validity of our system. The time evolution of temperature distribution on the whole of the stainless-steel wire was recorded by the IR thermograph when the wire was irradiated by the electron beam (EB). A time response of the wire temperature corresponding to the on/off of the EB irradiation was clearly observed, indicating that local EB heating was realized. In addition, the experimental time evolution of temperature at its transient phenomena was in good agreement with the theoretical calculation based on a one-dimensional (1D) equivalent-circuit model of heat flow coupled with electric current, where the thermal parameters, such as thermal conductivity and heat capacitance, were set to bulk values. Therefore, it can be concluded that our system is valid to evaluate the thermal conductivity of the 1D wire sample. For evaluating the thermal diffusivity of the wire sample, we applied a periodic EB irradiation by a rectangular wave with a frequency of 0.25 Hz. The thermal diffusivity was evaluated to be (2.8 ± 0.6) × 10−5 m2 s−1, which was seven times as large as that of bulk stainless steel. Our system can be applied to an AC calorimetry method for a 1D system sample after the analysis procedure is further modified.

To the Issue of Low-Alloyed Copper Alloys for Contact Wires

This paper is about a comparative analysis of the requirements of the Russian standard, the standard of the European Union and the PRC for overhead contact wires for electrified high-speed railways. New generation contact wires must have a high level of mechanical, electrical and operational properties. The Russian standard does not regulate the chemical composition of alloys used for the contact wires manufacture. Unlike the standards of the European Union and China, the Russian standard regulates the maximum value of the relative creep. Compositions, mechanical properties, electrical resistivity and recrystallization temperature for the contact wires with a cross section of 120 mm2 are given. The requirements for the material for the contact wire are presented. The need to use more durable conductive materials instead of copper is noted since mechanical loads and operating temperatures are constantly increasing. The values of mechanical properties, recrystallization temperature and creep of contact wires made of copper alloys are given. Based on the analysis results of the literature data and the experiments, alloys of the Cu-Mg system are recommended as a material for the contact wire manufacture for an overhead network system for high-speed railways.

Luttinger liquid coupled to Ohmic-class environments

We investigate the impact of an Ohmic-class environment on the conduction and correlation properties of one-dimensional interacting systems. Interestingly, we reveal that inter-particle interactions can be engineered by the environment's noise statistics. Introducing a backscattering impurity to the system, we address Kane-Fisher's metal-to-insulator quantum phase transition in this noisy and realistic setting. Within a perturbative renormalization group approach, we show that the Ohmic environments keep the phase transition intact, while sub- and super-Ohmic environments, modify it into a smooth crossover at a scale that depends on the interaction strength within the wire. The system still undergoes a metal-to-insulator-like transition when moving from sub-Ohmic to super-Ohmic environment noise. We cover a broad range of realistic experimental conditions, by exploring the impact of a finite wire length and temperature on transport through the system.

Study of Temperature Field Inhomogeneities in Parallel Wire Strand Sections under ISO834 Fire

An accurate prediction of temperatures of parallel wire strands is essential to determine the fire-induced mechanical responses of cable-supported bridges. In this paper, the theoretical formula applicable to the temperature field calculation of parallel wire strand sections is established based on the basic theory of heat transfer, and its accuracy is verified. An equivalent steel round bar numerical model of the parallel wire strand is established, and the temperature history of the parallel wire strand section under ISO834 fire is analyzed using the theoretical formula and the equivalent steel round bar numerical model. The results show that the heating law of each layer steel wires of the parallel wire strand section is basically the same and all have a tendency to approach the fire source temperature with the increase of fire time. Due to the existence of thermal resistance, large temperature gradients occur in the parallel wire strand sections. The temperature field of the parallel wire strand section shows more significant inhomogeneous distribution than that of its equivalent steel round bar section due to the influence of the cavities. It indicates that the traditional equivalent steel round bar model does not genuinely reflect the inhomogeneous temperature rising characteristics of the parallel wire strand section. The temperature of the surface layer steel wires of the parallel wire strand section and its equivalent steel round bar section is very close. In contrast, the temperature difference of the inner steel wires is significant, i.e., the parallel wire strand section has a larger temperature gradient than its equivalent steel round bar section.

Устройство бесконтактного измерения гололедной массы на проводах воздушных линий электропередачи

Ice buildup monitoring is essential to prevent wire breakage on overhead power lines. Conventional telemetry systems which are based on load cell sensors have some drawbacks as reflected in this paper. We suggest an innovative device for contactless ice buildup monitoring of overhead power line wires video recording the power line clearance. A specific algorithm for detecting the lowest point of wire sag has been provided. Also, we analyze a possibility of indirect contact sensor-free measurements of a wire temperature when the wire is being covered by icy deposits. A specific buildup type can be determined comparing a dew point and desublimation point as shown in this paper.

Burning Characteristics of Pyrotechnic Time-Delay Composition Subjected to Moisture and Heat

The combustion of pyrotechnic delay composition based on metallic fuel and perchlorate oxidizer involves complex reaction mechanisms and condensed phase heat release. Studies on the effect of aging on ignition/burning properties, and understanding of such multicomponent pyrotechnic delay mixtures are quite limited. The present work focuses on investigating the reaction kinetics, ignition, and combustion behavior of a zirconium/nickel (Zr/Ni)-alloy-based pyrotechnic delay mixture. Comparisons are presented between pristine and hygrothermally aged samples subjected to accelerated aging conditions under a constant temperature of 71°C and 95% relative humidity for 2 weeks. Activation energy versus reaction progress, ignition delay time as a function of maximum wire temperature, reaction zone temperature profile, and burning rate with respect to pressure are obtained from various experimental procedures. Results indicate that aging increases the ignition delay time and temperature rise time significantly, and a substantial decrement in the heat of reaction and burning rates along with incomplete combustion are evident.

Effect of axisymmetric magnetic field strength on heat transfer from a current-carrying micro-wire in ferrofluid

The effect of the strength of the self-induced magnetic field around a current carrying wire on thermomagnetic convection cooling in ferrofluid is experimentally and numerically investigated. Temperature-rise characteristics of the hot micro-wire for uniform Joule heating with different electric currents are compared to identify the relative importance of the strength of the axisymmetric magnetic field. Experiments are done with copper and platinum wires with current inputs adjusted to achieve the same Joule heating per unit length of wire. It was found that at high current supply (2A), mixing in ferrofluid is escalated due to thermomagnetic convection that resulted into 28% increase in average Nusselt number value which finally resulted into temperature drop of 8 K in comparison to DIW. Comparison of results for different self-induced magnetic field strengths in ferrofluid and deionized water clearly show that the observed cooling phenomenon is due to the self-induced magnetic field interacting with the magnetic fluid rather than natural-convection or other nanofluid-related mechanisms. For 1.83 W J heating, the temperature of the copper wire is 6 K lower than that of the platinum wire. Temperature and velocity contours obtained from simulations based on a 2-D single-phase model including a temperature-dependent magnetic body force provide flow visualization and further confirmed that the thermomagnetic cooling is responsible for the observed behaviour.

Self-Consistent Schrödinger-Poisson Study of Electronic Properties of GaAs Quantum Well Wires with Various Cross-Sectional Shapes.

Quantum wires continue to be a subject of novel applications in the fields of electronics and optoelectronics. In this work, we revisit the problem of determining the electron states in semiconductor quantum wires in a self-consistent way. For that purpose, we numerically solve the 2D system of coupled Schrödinger and Poisson equations within the envelope function and effective mass approximations. The calculation method uses the finite-element approach. Circle, square, triangle and pentagon geometries are considered for the wire cross-sectional shape. The features of self-consistent band profiles and confined electron state spectra are discussed, in the latter case, as functions of the transverse wire size and temperature. Particular attention is paid to elucidate the origin of Friedel-like oscillations in the density of carriers at low temperatures.

Research on Anti-Icing Technology of High Voltage Line Insulator Based on Advanced Sensor

The insulator has an ice flashover failure. To reduce the calculation error of the equivalent icing thickness of transmission lines due to the insufficient number of sensors, a new online monitoring device for wire icing based on 3 sets of force sensors and inclination sensors was designed. The device integrates multiple monitoring functions such as micro-meteorology, wire temperature, distributed multi-rod tension, and images. The study found that the main reason for the ice flash of insulators is that the ice bridging the insulation on the string skirt. The high conductivity of melting ice water causes the ice flash voltage to be too low. A water curtain that blocks the melted ice water with high conductivity from forming a flashover channel. It is a basic measure to improve the ice-coated insulation and the flashover voltage of the ice string.

Thermal modes of operation of power-current contact of electric transport during conduct of bench tests

Purpose. Analysis of the results of bench tests of sliding electrical contacts of electric vehicles, in order to determine the thermal regime of the sliding contact.
 Methodology. The initial data were obtained during field experiments on a specialized stand in the laboratory, which were carried out to determine the wear of the contact wire inserts of different types for pantographs of electro-rolling stock of railways. To determine the contact wire temperature at the place of sliding contact, a non-destructive non-contact method of control using a thermal imager was used.
 Findings. During the experimental part of the research, the thermal imaging photographs were obtained, they recorded the temperatures at the place of sliding contact between the insert of the pantograph of the electric rolling stock and the contact wire installed on the test disk. These temperature values were recorded with a certain time interval, which allowed to build the dependences of changes in thermal regime over time, to determine the heating time constant of the "insert-contact wire" of the test bench and to obtain the final temperature value at the end of tests. Accepting the insert sample in which the minimum temperature in the area of sliding contact is as a reference, it becomes possible by the value of the temperature of the contact wire in the area of sliding contact to predict the final test result of other types of pads.
 Originality. Indicators of temperature modes of sliding contact of electric vehicles during bench tests are obtained for the first time, the proposed relative temperature indicator allows to predict the results of bench tests of qualitative indicators of sliding contact of electric vehicles..
 Practical value. Bench tests of inserts of current collectors of electric vehicles are a long procedure, the normative indicator of the number of passes of the current collector on the stand is equal to 500 thousand passes, which requires significant expenditure of time, energy, human resources and others. The indicators proposed according to the test results, namely the heating time constant and the relative temperature index, allow to carry out two-stage tests. At the first stage, with a duration of 10 thousand revolutions of the test bench disk, the proposed indicators are determined and compared with the corresponding reference, in case of their compliance it becomes possible to predict the final test result as successful (contact wire wear less than normal) or unsuccessful. In the latter case, the need for the second stage of testing up to 500 thousand revolutions is questionable, because the end result will be negative, and the significant resources will be involved in the test, and therefore these tests are impractical.

Separation characteristics of an integrated temperature-controlled micro gas chromatography chip

Compared with traditional laboratory gas chromatograph, portable gas chromatograph has the advantages of fast detection, low power consumption, lost cost and possible applications out of Lab. In this paper, aiming at replacing the traditional column thermostat, we presented a 4 cm · 4 cm micro gas chromatography (μGC) chip with a thickness of about 1 mm and a column length of 3 m integrating the Pt heating wire and snake-shaped temperature sensor, which greatly reduces the power consumption and volume of the portable gas chromatograph without losing the separation performance of the μGC chip. The integrated μGC chip was fabricated by micro electro mechanical systems (MEMS) process and its temperature was controlled in closed-loop by fuzzy proportion integration differentiation (PID) algorithm. Experimental results indicate the temperature control accuracy under constant temperature can be up to ±0.05 °C. When heating to 180 °C, the power consumption is less than 15 W. The chip has good separation properties when it was used to detect 4 kinds of benzenes, 8 kinds of alcohol mixtures and 10 kinds of alkane mixtures.

Application of MIG Welding Process of Mild Steel Wire in Additive Manufacturing

The purpose of this study is to investigate the forming characteristics of single-pass Metal Inert Gas (MIG) welding wire for multi-layer additive manufacturing parts. Influences of arc current, arc voltage, arc distances, welding speed, wire feed speed, temperatures and heat input on layer formation were analyzed. The deposition of material by MIG process is controlled by a robot (ABB) controller for constructing walls of rectangular box shape. The samples were measured with a microhardness testing and tensile testing onto the welded bead created by the additive manufacturing technique. It was found that the mechanical properties of microhardness values are between 151.70 to 155.80 HV and the tensile strength values are between 472.71 to 491.12 MPa according to transverse and longitudinal sections of the specimens.

A Study on the Effect of Bond Wires Lift-Off on IGBT Thermal Resistance Measurement

Bond wire lift-off will cause an increase of remaining wires’ power dissipation, which usually is ignored for healthy modules. However, only partial wires’ power dissipation transfers through thermal path from junction to case, which will lead to overestimate the whole power dissipation from collector to emitter pole and underestimate the calculated thermal resistance using the proportion of temperature difference to power dissipation. A FEM model is established to show the change of heat flow after bond wires were removed, the temperature of bond wires increases, and the measured thermal resistance decrease after bond wires lift-off. It is validated by experimental results using open package Insulated Gate Bipolar Transistor (IGBT) modules under different current conditions. This conclusion might be helpful to indicate the bond wires lift-off and solder fatigue by comparing the change of measured thermal resistance. Using the Kelvin setup to measure thermal resistance will cause misjudgment of failure mode due to the ignoring of wires’ power dissipation. This paper proposed that the lift-off of bond wires will lead to underestimating the thermal resistance measurement, which will overestimate the lifetime of IGBT module and misjudge its state of health.