Wire Coil Research Articles

Single Stretch Wire and vibrating wire measurement system for characterization of multipole accelerator magnets

A stretch wire magnetometer is a versatile instrument and can be treated as the primary standard of magnetic qualification of accelerator magnets. Bhabha Atomic Research Centre has developed a Stretch wire magnetic measurement system to cater to the requirements of magnetic measurements on accelerator magnets. This bench also includes a vibrating wire system. The scheme used in this instrument for measurements of magnetic flux ensures drift compensations after each scan. This feature along with post-signal processing gives an accuracy of homogeneity measurements comparable to that of a rotating coil magnetometer. Unlike conventional stretch wire systems, wire moves in the r-z plane (along r-axis) at different azimuthal angles. This provides the opportunity for drift compensation at each scan. This has immensely enhanced the measurement accuracy of non-homogeneity of integral fields to less than 3 units. The same is cross-verified with a rotating coil system. The comparison between rotating coil and stretch wire is presented. The Paper gives the step-wise procedure for the measurement of key performance indicators of an accelerator magnet. This paper brings out salient features of the system along with design and calibration results.

ДОСЛІДЖЕННЯ ВПЛИВУ ІМПУЛЬСНИХ ПРОЦЕСІВ В ОБМОТКАХ ТРАНСФОРМАТОРА

The article examines the existence of uneven voltage distribution under the action of transient voltage, which is the main cause of insulation breakdown of power transformers. In fact, the winding of the power transformer has no tap and cannot be directly used to measure the impulse voltage. The study of pulse voltage distribution measurement is important and practical in engineering. The voltage distribution for the isolated neutral, when the current does not flow through the winding ipr = 0, occurs according to the exponential dependence, and the amount of overvoltage is equal to the initial voltage on the winding of the transformer, which decreases. When the induced voltage is varied along the winding of a transformer with an isolated neutral in steady state, the entire winding takes the same potential with respect to ground and the steady voltage is a straight line. It follows that in the case of an insulated neutral, the end of the winding must have the same insulation as the beginning. The change in maximum voltage is presented when U0 changes in the range from 550 kV to 850 kV. In the work, the change of U0 from values (550-850 kV) to 0 V was studied, with the length of the coil wire x=l= 100 m. Thus, in both cases, it is not difficult to determine the sum of the amplitudes of individual harmonics at any point of the winding. During the development of self-oscillations, the voltage exceeds the set value, and tends to decrease the frequency of self-oscillations. On the basis of the conducted research, transient overvoltage distributions in the transformer windings were calculated. These results will be useful for designers to evaluate the resistance of transformer insulation to transient voltages and further optimize the graded longitudinal insulation. Transient overvoltage distributions in transformer windings are modeled. It was concluded that the impulse voltage distributions in the transformer windings are mainly related to the high-frequency components of the winding voltage.

Untethered Nanotextured Thermopneumatic Soft Actuators Operable with Different Stimuli: Thermal Blowing, Infrared Light, and Electromagnetic Field

In this study, untethered nanotextured thermopneumatic soft actuators (UTPSAs) were developed using a soft elastomer body encapsulating a volatile fluid (Novec 7000), which underwent a phase change (evaporation) when stimuli that convert energy into heat were applied using wireless transmission. Herein, we analyzed three types of stimuli: (i) thermal blowing, (ii) irradiation with infrared light, and (iii) electromagnetic energy transmission. In the third case, an electromagnetic field induced an electric current in a wire coil embedded in an elastomeric body, thus providing Joule heating to induce fluid evaporation. The bending curvature and force generated during bending were examined under various operational conditions, which enable one to select the optimal operating mechanism of UTPSAs for a specific environment. Specifically, diverse operating capabilities of UTPSAs are expected to be useful in dynamic environments, e.g., rescue situations. In addition, as a potential application, a crawler-configured UTPSA was fabricated, and its operation was demonstrated.

A novel whole-head RF coil design tailored for concurrent multichannel brain stimulation and imaging at 3T

PurposeMultichannel Transcranial Magnetic Stimulation (mTMS) [1] is a novel non-invasive brain stimulation technique allowing multiple sites to be stimulated simultaneously or sequentially under electronic control without movement of the coils. To enable simultaneous mTMS and MR imaging, we have designed and constructed a whole-head 28-channel receive-only RF coil at 3T. MethodsA helmet-shaped structure was designed considering a specific layout for a mTMS system with holes for positioning the TMS units next to the scalp. Diameter of the TMS units defined the diameter of RF loops. The placement of the preamplifiers was designed to minimize possible interactions and to allow straightforward positioning of the mTMS units around the RF coil. Interactions between TMS-MRI were analyzed for the whole-head system extending the results presented in previous publications [2]. Both SNR- and g-factors maps were obtained to compare the imaging performance of the coil with commercial head coils. ResultsSensitivity losses for the RF elements containing TMS units show a well-defined spatial pattern. Simulations indicate that the losses are predominantly caused by eddy currents on the coil wire windings. The average SNR performance of the TMSMR 28-channel coil is about 66% and 86% of the SNR of the 32/20-channel head coil respectively. The g-factor values of the TMSMR 28-channel coil are similar to the 32-channel coil and significantly better than the 20-channel coil. ConclusionWe present the TMSMR 28-channel coil, a head RF coil array to be integrated with a multichannel 3-axisTMS coil system, a novel tool that will enable causal mapping of human brain function.

Performance enhancement of a hybrid photovoltaic/thermal system using wire coils inside the cooling tube: numerical and experimental case.

There are several strict reasons to overcome the dependence on fossil fuels and count on renewable energy sources such as solar energy. In this study, a numerical/experimental investigation on a hybrid photovoltaic/thermal system is carried out. A hybrid system would achieve higher electrical efficiency by reducing panel surface temperature, and the heat transferred could have further benefits. Using wire coils inside cooling tubes is a passive method selected in this paper to improve heat transfer. The appropriate number of wire coils was determined using numerical simulation, and then the experimental study began in real-time. Different flow rates with different pitch to diameter ratios for wire coils were considered. The results show that placing three wire coils inside the cooling tube would increase the average electrical and thermal efficiency by 2.29 and 16.87%, respectively, compared to the simple cooling mode. According to the results, if a wire coil is used in the cooling tube, a 9.42% increase in the average total efficiency based on electricity generation during a test day would appear compared to the simple cooling. A numerical method was applied again to evaluate the results of experimental tests as well as observe the phenomena in the cooling fluid path.

Exploration of ARC-class reactor vessel and divertor cooling system

ARC (Affordable, Robust, and Compact) is a compact tokamak design proposed by Commonwealth Fusion Systems and the Plasma Science and Fusion Center at the Massachusetts Institute of Technology.ARC features REBCO (Rare Earth Barium Copper Oxide) high temperature superconducting magnets, demountable coils, a replaceable vacuum vessel and a liquid immersion blanket (LIB). The LIB is a Li2BeF4 (FLiBe) molten that provides cooling, tritium breeding, and neutron shielding. The compact dimensions of ARC result in very high heat fluxes on the first wall (0.4MW/m2) and the divertor (10MW/m2). These heat fluxes mandate a high heat transfer coefficient in the cooling channels that cannot be achieved without adopting heat transfer enhancement techniques. The scope of this work is to analyze the FLiBe flows through the vacuum vessel channels, and the exploration of different passive heat transfer enhancement techniques to provide adequate cooling to the vessel, which must withstand considerable heat flux and volumetric power generation. Minimum cooling requirements for vessel and divertor are evaluated, and the performance of different turbulence promoters is compared to find the most advantageous design. In particular, wire coil inserts decrease pressure drops by 39% with respect to twisted tapes inserts while providing the same cooling performance.

Numerical investigation of the injection angle of carrier nanoparticles under the effect of different magnetic fields

Cancer is considered as one of the most leading causes of human mortality. There are different ways for treatment of cancer each has their own pros and cons. Magnetic drug targeting (MDT), among others, is one of the most promising methods for cancer treatment with minimum side effects. In the present study the effect of injection angle and injection rate of nanoparticles on the capture efficiency (CE) of nanoparticles in a 3D blood vessel. Three different magnetic sources have been considered, including permanent magnet, current carrying wire, and coil wire. The parameters considered in this study, include injection angle (30°<α<90°), and injection rate (0mm3.s-1≤Q̇inj≤320mm3.s-1). Regarding the injection site, two scenarios have been considered, (1) injecting from the same side of the magnet location; and (2) injecting from the opposite side of the magnet location. Finite element (FE) method was used to solve the governing equations. Results showed that the maximum values of CE are related to the current carrying wire, permanent magnet, and coil wire with the value of 94%, 80%, 68%, respectively. It was found that the maximum CE of nanoparticles (91.7%) in scenario 2 is obtained at injection rate of Q̇inj=31.4mm3.s-1 when the current carrying wire was used as the magnetic source. Also, it was revealed that no particle is captured at 0≤Q̇inj≤62.8mm3.s-1 in scenario 1. Finally, it was revealed that for all injection angles and rate, the CE of nanoparticles in scenario 2 is higher than that of scenario 1.

Mixed convection phenomena in tubes with wire coil inserts

A numerical investigation of the flow and heat transfer in a helical coil in laminar and transitional flow regime under mixed convection conditions is presented. The continuous separation and reattachment of the boundary layer caused by the wire coil, that interrupts the flow near the tube all, and the swirl induced by the helical shape of the insert, are identified as the mechanism for heat transfer enhancement. Simulations in the Reynolds number range 200<Re<1500 show the role of mixed convection on heat transfer, as the flow dynamics is sensitive to the buoyancy forced induced by the tube wall heating. The interaction of the secondary swirl flow with the buoyancy motion is investigated in this work, with the aim of clarifying the range where heat transfer could be worsened by the presence of the helical coil. The investigation has been undertaken considering a helical coil of geometrical characteristics e/D=0.071 and p/D=1.5 and water as working fluid. Validation with experimental results of friction factor and Nusselt number is also presented.

Optimization configuration of scrubber steel wire coils as porous materials for augmenting the performance of hemispherical distillers

BackgroundThe present study aims to improve the productivity of hemispherical solar distillers to overcome the problem of freshwater shortage facing many countries of the world, especially remote countries, due to population increase and climate changes. To achieve this goal, scrubber steel wire coils were incorporated in the basin of a hemispherical distiller as porous materials and energy store materials. To identify the best configuration of installation and form of scrubber steel wire coils that provides the highest thermal efficiency of hemispherical solar distillers (HSDs), two configurations were considered for installing and forming the scrubber steel wire coils inside the basin; spiral form and cake form. MethodsTo examine their performance experimentally, besides to a traditional HSD (THSD), two new HDSs, one containing spiral-shaped coils of scrubber steel wire (HSD-SSCSSW), and one HDS with cake-shaped coils of scrubber steel wire (HSD-CSCSSW) were constructed and studied under same climate weather conditions. Significant findingsOutcomes showed that the HSD-CSCSSW is the best configuration that provides the highest hemispherical distiller performance. Its distillate accumulation reached 7110 mL/m2, while THSD accumulation totaled 4830 mL/m2. The accumulation productivity of the HSD-CSCSSW is 1.472 times higher than the output of THSD. Outcomes proved that utilizing the scrubber steel wire coils in the shape of a cake is a good choice which augments the thermal and exergy efficiencies by 46.47 and 101.1%.

A Useful Experiment for Teaching Resistance of a Wire as a Function of Temperature

We have developed a new simple experiment for the students where they can get a quantitative measure of how the resistance of a wire depends on the temperature of the wire. The only materials required are a copper wire coil, a DC voltage source, a digital ohmmeter, and a calorimeter with an analog thermometer. The students discover a linear relationship between temperature and resistance. The temperature coefficient is easily calculated from the slope of the graph and compared with the standard values. The experiment, although simple to perform and feasible with minimal equipment, does provide reasonable results and is appropriate for either high school students or an undergraduate physics laboratory. Also, the work would be of interest to teachers in an introductory-level physics course.

Thoracoscopic Resection of Lung Nodules following CT-Guided Labeling in Children and Adolescents with Solid Tumors

Resection of lung metastases in children with solid tumors is regularly hampered by limited intraoperative detectability and relevant operative trauma of the open surgical access. The aim of this study was to analyze thoracoscopic resection of lung metastases in children following CT-guided labeling with coil wires. We retrospectively analyzed data of children and adolescents undergoing this approach at our institution between 2010 and 2022 with regard to technical aspects as well as surgical and oncological data. Within this period, we performed this procedure on 12 patients wherein we resected 18 lesions (1-5 per patient). The median age of patients was 178 months (51-265). The median duration of coil wire placement was 41 min (30-173) and the median surgery time was 53 min (11-157). No conversions were necessary and no intraoperative complications occurred. Complete microscopic resection (R0) was achieved in all labeled lesions and malignant tumor components were found in 5/12 patients. Our study shows that with a careful patient selection, thoracoscopic resection of lung metastases after coil wire labeling is a safe and reproducible procedure in children. Using this approach, lesions that are expected to have a reduced intraoperative detectability during open surgery become resectable. Patients benefit from the minimally invasive surgical access and reduced operative trauma.

The Relativity of Energy and the Reversal of Time is a Shift in Perspective

The Relativity of electrical engineering explains the reversal of time as a reversal of current resulting from electrical or magnetic reactance. This affects the frame of reference of electricity, but this is not obvious to the observer. Polarity of the sign of a simulator's time interval is derived from its power and energy assessment. Current reversal is equivalent to time reversal. Reversal of current increases voltage differences in deference to common sense. Coils of wire become generators without any significant prime mover. This requires a severe reduction of input power so as to avoid repressing these effects. The foreseeable consequence is a severe reduction of the size of energy farms putting electrical energy into the hands of third-world countries and pragmatic industry. The cost of energy can be integrated into the cost to manufacture an appliance possessing its own, built-in power supply.

Experimental study on the mechanical properties of the hot-cast anchor of steel cables at elevated temperatures

Although commonly used as critical joints in prestressed space structures, hot-cast anchors tend to be weak in the fire. Currently, there is a lack of research on the mechanical properties of the hot-cast anchor at high temperatures. In this study, pull-out tests were performed on hot-cast anchors of Galfan-coated steel cables and locked coil wire ropes at elevated temperatures to determine failure mode, failure mechanism, and mechanical properties at high temperatures. The following conclusions were obtained: (1) The ultimate tensile strength of the hot-cast anchor decreased at an accelerated rate with increased temperature. When the temperature reached 200 °C, it decreased to about 80% of that at room temperature. (2) The peak point displacement of the hot-cast anchor of the locked coil wire rope increased significantly with increased temperature, while the Galfan-coated steel cable did not. (3) The stiffness of the hot-cast anchor decreased with increased temperature. When the temperature reached 200 °C, it decreased to about 75% of that at room temperature. (4) Additionally, this study proposed a prediction formula for the ultimate tensile strength of a hot-cast anchor at different temperatures, thus providing a theoretical basis for the fire resistance design of hot-cast anchors.

Broadband Pulse Injection Probe With Improved Injection Efficiency for Conducted Electromagnetic Susceptibility Test

A broadband pulse injection probe with improved injection efficiency for conducted electromagnetic susceptibility (EMS) is proposed in this article. Improved injection efficiency is effective and crucial for conducted EMS testing of electronic devices. The effect of parameters, such as coil material and wire diameter, the number of coil turns, and the distance between the coil and the shielding shell on probe injection efficiency, is investigated in this article. By using low-impedance coils, symmetrical winding methods, and size-matched shielded shell, the broadband pulse injection probe with improved injection efficiency is obtained. The proposed broadband pulse injection probe was calibrated, and an injection efficiency comparison test was performed, proving that the proposed probe has improved injection efficiency. Meanwhile, the proposed injection probe performs well in EMS testing in the 9-kHz–400-MHz frequency range. These results will be of great significance for the effective acquisition of EMS test data and the optimal design of electromagnetic compatibility (EMC) of integrated circuits (ICs).

Optimal analysis on coil and rotor in a diamagnetically airflow energy harvester

In this paper, the proposed diamagnetic levitation structure was studied to explore its potential in energy harvesting. It is proved that the floating magnet rotor can be levitated stably under the joint action of two highly oriented pyrolytic graphite (HOPG) sheets and the lifting magnet. Simulation calculation was carried out to analyze the influence of different coil radius and wire diameter on peak voltage and average power in scheme A or scheme B, so as to obtain appropriate layout and wire diameter for the coils which was built the experimental platform. Subsequently, the center hole, notch radius and thickness of the floating rotor are analyzed by experiment. And the influence of different parameters on rotation speed of the rotor and peak output voltage of coils is obtained. Through experimental results, it is found that the notch radius of the floating rotor has the greatest influence on the rotation speed of the rotor. Based on the experiment, a new-type rotor was designed, with an outer shell to reduce the notch radius. Compared with the original floating rotor, there was 49.73% increase in voltage, 55.70% increase in rotation speed and 124.50% increase in power according to the experimental results. Test was performed with the optimization, the LED array of Zhengzhou University logo, which was composed of 60 LED lights, was lighting up. According to the oscilloscope measurement, the diamagnetic levitation energy harvester has an output voltage up to 1.294 V and average power of 60.67 mW under gas flow rate of 3000 sccm and nozzle exit velocity of 6.173 m/s. Obviously, the new-type rotor proposed in this paper could significantly increase the energy conversion efficiency, and make the future application of airflow energy harvester a step further.

Combined influence of rectangular wire coil and twisted tape on flow and heat transfer characteristics in square mini-channels

Combined influence of rectangular wire coil and twisted tape on flow and heat transfer characteristics in square mini-channels

Helically-coiled-wire-induced swirl flow heat transfer and pressure drop in a circular tube under velocities controlled

Systematic measurements of the swirl flow heat transfer by the helical coil-wire and the pressure drop across the helical coil-wire were made by the experimental water loop flow with exponentially increasing heat input at mass velocities G = 3928 to 13,496 kg/m2s, inlet liquid temperatures Tin=284.14 to 307.57 K and inlet pressures Pin=763.80 to 1027.85 kPa. Systematic measurements of the pressure drop across the helical coil-wire were performed without heating circular tube. The measurements were performed on the inner surface of a SUS304 circular test tube with an inner diameter of 6 mm, a heated length of 59.7 mm, and a thickness of 0.5 mm, in which a helical coil was inserted. SUS304 helical coiled wire with wire diameter dw=2.025 mm, coil diameter Dc=3.4917 mm, total length l = 370 mm, coil pitch 360° rotation pc=37.222 mm, and coil pitch ratio yc=pc/d = 6.204 was employed. The relationship between swirl velocity and pump input frequency and that between fanning friction factor and Reynolds number (Red=1.949 × 104 to 1.274 × 105) were clarified beforehand. On the other hand, the RANS (Reynolds mean Navier-Stokes simulation) equations for the k-ε turbulence model in a circular tube of 6 mm diameter and 626 mm length with helical coil inserted, considering the temperature dependence of the thermophysical properties concerned, were numerically solved for the heating of water on a heated section of 6 mm diameter and 60 mm length under the same conditions as the experiment by using the PHOENICS code. The helical coiled wire of dw =2.025 mm, Dc=3.4917 mm, l = 370 mm, pc=37.222 mm and yc=6.204 was installed at the same experimental location. The surface heat fluxes q and average surface temperatures Ts,av on a circular tube with a helical coil of yc =6.204 obtained theoretically were compared with the corresponding experimental values on the graph of q versus temperature difference between average heater inner surface temperature and liquid bulk mean temperature ΔTL [=Ts,av-TL, TL=(Tin+Tout)/2]. The numerical solutions for q and ΔTL were almost identical to the corresponding experimental values for q and ΔTL, with deviations from 0 to +20% for the ΔTL range tested here. The numerical solutions of the local surface temperature (Ts)z, the local average liquid temperature (Tf,av)z, and the local liquid pressure drop ΔPz were also compared with the corresponding experimental values of (Ts)z, (Tf,av)z, and ΔPz against heated length L or distance from the test section inlet Z, respectively. The numerical solutions of (Ts)z, (Tf,av)z and ΔPz differ from the corresponding experimental data of (Ts)z, (Tf,av)z and ΔPz within ± 5%. The thickness of the conductive sublayer δCSL [=(Δr)out/2] and non-dimensional thickness of the conductive sublayer y+CSL [=(fF/2)0.5ρlusw,cδCSL/μl] for turbulent heat transfer on a circular tube with helical coiled wire are clarified on the basis of numerical solutions in the swirl velocity usw,c ranging from 5.108 to 17.146 m/s. Correlations of Nusselt number Nud, δCSL, and y+CSL for the swirl flow heat transfer in a vertical circular tube with helical coil wire are also derived.

Validation of a new methodological approach for the selection of wire-coil inserts in thermal equipment

• New methodology to select wire coils for thermal equipment enhancement. • The estimation of TSP for a given insert categorizes its hydraulic performance. • Method experimentally validated for heat transfer enhancement in a solar collector. • 4 wire-coils selected with differentiated behaviours in their friction factor curves. • Pressure drop and heat transfer tests were performed in collectors with wire coils. The use of wire-coils is especially relevant at low Reynolds numbers (below the critical number to turbulent flow in smooth tubes) according to its inherent positive features such as the advance of transition onset and, if they present suitable geometric characteristics, the establishment of an extended transitional flow in a critical Reynolds number interval [ Re CL - Re CT ], with a predictable friction coefficient and Nusselt number. This paper presents the experimental validation of a new methodology based on the evaluation of a non-dimensional geometry-based parameter: the TSP (Transition Shape Parameter) that allows to predict the friction coefficient evolution with wire-coil inserts and enables to compute the extension of the transitional flow region. The close relationship between hydraulic and thermal performance of wire-coil inserts makes this methodology a valuable tool for selecting the most appropriate wire-coil geometry for a given tubular heat exchanger. It is observed that to promote an increase in heat transfer, the value of the Re CL of the wire coil must be less than the operating Reynolds number range of the equipment. Thus, the Re CL - Re CT interval of the insert should fall into this range. In order to validate the methodological approach, an application to harp-type solar thermal collectors with typical Reynolds number range [40-6000] is presented. Four representative wire-coils, with a wide geometrical range characterized by TSP values of 759, 196, 35.3 and 3.1 (exhibiting significant differentiated behaviours in their friction factor curves and critical Reynolds numbers) were inserted inside the risers of a modified solar collector and experimentally tested at laboratory conditions. Static temperature at different locations at the absorber plate, and pressure drop were measured to obtain friction factor and Nusselt number inside riser covering the laminar, transitional and low-turbulent regions. For a general application with friction factor constraints the most suitable wire-coil geometry is the TSP W 02 = 196 with a range of critical Reynolds number of Re CL = 663 and Re CT = 2286 and Nu ¯ w 02 / Nu ¯ s = 2.21 for Re = 300 - 3000 with f ¯ w 02 / f ¯ s = 3 , 82 . However, for the case study presented (a harp-type solar collector) it is feasible to insert the third wire-coil geometry TSP W 03 = 35.3 due to its early transition, with a range of critical Reynolds number of Re CL = 364 and Re CT = 2324 , and Nu w / Nu s = 1.35 for Re = 300 with a high friction factor augmentation f ¯ w 03 / f ¯ s = 18.84 . This geometry also promotes the highest absorber temperature reduction. The greatest temperature reduction is observed in the range of Reynolds numbers [700-2000], reaching approximately 6 °C, which represents approximately 15%.

Experimental and CFD analysis of wire coil turbulators in biomass boilers

To achieve as complete fuel burnout with as little excess air as possible, small wood log boilers (&lt; 50 kW) use stage combustion. The first stage is often a process similar to downdraft gasification that consequently produces a flue gas laden with particulates. To prevent the build-up of solids and promote heat transfer in pipes of the convective part of these boilers, wire coils are used. The paper presents their in-situ examination together with CFD analysis. The analysis is carried out in a 460 mm long pipe, with a diameter of 82.5 mm, equipped with different wire coils for flue gas temperatures in the range between 300?C and 150?C. The analyzed coils are with and without a conical spring at their free end. The addition of this conical top is economical and should influence the rotation of the core flow. Proper pipe surface cleaning limited the analyzed wire coil designs to the dimensionless pitch, p/d, in the range between 0.36-0.61, dimensionless wire diameter e/d = 0.04-0.1, and pitch to wire diameter ratios p/e = 3.75-14.3, and three different angles (60?, 90?, and 120?) of the conical top. The goals are to find the optimal flue gas velocity for the given operating conditions, pipe, and wire coil dimensions, and to investigate the addition of the conical top on heat transfer enhancement. Several evaluation criteria are used to achieve the goals.

Clinical Practice Guidelines for the Use of Transcranial Direct Current Stimulation in Psychiatry.

Clinical Practice Guidelines for the Use of Transcranial Direct Current Stimulation in Psychiatry.