Sheet Insulation Research Articles

Research on insulation design of 10 kV medium-voltage cascaded energy storage system

Abstract The insulation design of a medium-voltage cascaded energy storage system is very important due to its direct access to the AC medium-voltage network. This paper focuses on improving the reliability and safety of the system operation, and realizes the insulation design of a 10 kV medium-voltage cascaded energy storage system through the selection of insulation materials and structural innovation. In the structure, high insulation sheet molding plastic was used to suspend the battery. The ultra-low conductivity coolant was used to enhance the insulation performance between battery modules. The stability and practicability of the insulation structure are demonstrated by effective test methods. The research shows that the medium voltage insulation design meets the insulation requirements of the 10 kV voltage class, and has high industrial practical value for the project of medium voltage cascaded energy storage system.

Used Polyethylene Bags to form Electric Insulation Sheet and Tape: An Innovative Frugal Approach

Used Polyethylene Bags to form Electric Insulation Sheet and Tape: An Innovative Frugal Approach

Reducing the energy consumption of buildings by implementing insulation scenarios and using renewable energies

The reduction of fossil energy sources, the harmful environmental effects caused by high energy consumption, and the increase in the share of energy consumption in the building sector have increased the need to pay attention to building energy consumption. This study offers an intricate examination of a residential locality in Florida, with a particular emphasis on the architectural design of a building, issues related to the local environment and several possibilities for enhancing energy efficiency. It examines the influence of the environment in the area on architectural design and investigates two different possibilities for improving energy efficiency. The first scenario focuses on assessing thermal insulation and shading, while the second scenario envisions utilizing photovoltaic cells to achieve a zero-energy building. The proposed initiatives seek to optimize energy efficiency, save expenses, and foster environmental sustainability in the region. In this research, the total energy consumption of a building with residential use in the climate of the case study was validated by DesignBuilder® simulation software, and the results obtained from the software. Then, using the standard of energy consumption of the building, various strategies for optimizing energy consumption have been simulated. Using energy simulation software, solutions for using external horizontal awnings and installing a thermal insulation sheet on the external wall of the building were investigated, which resulted in a reduction of 200 kWh of energy consumption compared to the normal state. Then, the building’s energy consumption intensity was calculated for each of the proposed solutions, and the building’s energy classification was determined with energy star and LEED standards.

Synthesis of bio-based toughening phosphorus-nitrogen flame retardant and study on high toughness EPS flame retardant insulation sheet

In this paper, a variety of biological phosphorus-nitrogen synergistic flame retardants were synthesized from the perspective of molecular design. At the same time, tannic acid (TA) modified graphene (GE) and multiwalled carbon nanotubes (MWCNTs) nanomaterials were prepared by combining nanocomposite technology. Then, the flame retardant was applied to expandable polystyrene (EPS) through a coating process to prepare toughened composites. And the effect of the synthesized high-efficiency phosphorus-nitrogen flame retardant on the flame retardancy efficiency and brittleness of EPS was studied. The flame retardant (PAU) was synthesized by complexing phytic acid (PA) and urea (U) in an aqueous medium, and then using polydopamine (PDA) as an adhesive. Next, on the basis of PAU, using GE and MWCNTs as tougheners, EPS-PAUCG composites were prepared by coating method. Research has found that in the UL-94 test, the flame-retardant EPS-PAUCG composites could reach V-0 level. In the CCT experiment, compared to pure EPS, the PHRR, THR, PSPR, and TSP of EPS-PAUCG2 decreased by 88.4 %, 72.3%, 74.9 %, and 80.9 %, respectively. Through mechanism analysis, it has been proven that PAUCG undergoes thermal decomposition to form a dense expandable protective carbon layer, preventing further degradation of the matrix. In addition, compared to EPS, the compressive strength of the EPS-PAUCG2 composites have increased by 22.5%. This was because the composites contained GE and MWCNTs with high molecular chain structure rigidity and specific surface area, which had a toughening effect of ductile particles.

Incorporating phase change materials in geothermal energy piles for thermal energy storage

Introduction
 Geothermal energy piles (GEPs) are foundation elements that are installed in the ground to support the weight of the building to a competent strata. Energy loops are installed into the piles to allow heat rejection or extraction via the circulation of fluid through the loops. In winter, low-grade heat is extracted from the ground (source) and transferred to the building (sink) to achieve space heating. Conversely, in summer, heat is removed from the building and rejected into the ground to achieve space cooling. The system relies on the temperature gradient between the ground and the ambient air temperature; where in winter, the ground temperature is higher than the air temperature, while in summer, the opposite is true. Thus, the system can sustainably and continuously supply the heating and/or cooling demand of a building once the temperature gradient between the ambient air and the ground is maintained. To improve the sustainability and performance of the system, the heat energy rejected into the ground can be stored and used at a later time when space heating is required [1]. Energy storage substances such as phase change materials (PCMs) can be incorporated into energy piles to store the heat that is rejected into the ground to improve the performance of the GEP system [2]. PCMs are materials that stores or releases heat energy during phase transition. Many researchers including [3,4] have reported using PCMs in buildings to improve thermal comfort and minimise the energy demand during heating and cooling periods, however, not much work has been done with regard to incorporating them into pile foundations to improve the performance of GEP systems.
 Thus, this study carried out a laboratory experiment to investigate the effect of the addition salt hydrate PCM on the energy performance of geothermal energy piles.
 Laboratory test and procedure
 In this study, lab-scaled models of energy piles were constructed, with and without PCM. The piles are characterised by a length and a diameter of 300 mm and 100 mm, respectively. In order to add PCM into the piles, the PCM was encased and sealed in a PVC tube with an inner and an outer diameter of 6mm and 8mm, respectively. The same size of PVC tube was used for the energy loops. The energy loop (U-shape), and the encased PCM incorporated tubes are attached together and placed in the mould prior to concreting, for the pile model with PCM (see Figure 1a). Whereas only the energy loop was installed in the control sample.
 In the test setup, a layer of sand (220mm thick) was placed and compacted in an insulated wooden box (520mm × 520mm × 520mm). Afterwards, the pile was then installed at the center of the box and then filled with sand, in layers and compacted. An insulation sheet was used to cover the top of the box to prevent heat loss and the ambient air temperature influencing the tests’ results. Water at a temperature of 32°C, was circulated through the pile continuously for a duration of 4 days (96 hours). Instrumentations were installed in the pile and soil to monitor and record the changes in temperature during the tests (see Figure 1b).
 Results and discussion
 Figure 1c shows the results comparing the average energy rejected, and stored, in the ground for the piles with and without PCM. The maximum heat energy stored at the beginning of the test was found to be about 460W and 360W for the control and PCM piles. However, at the end of the tests, the energy stored was 230W and 430W for the control and PCM pile, with an average energy stored as shown in Table 1. The addition of salt hydrate PCM absorbs the heat rejected into the pile, consequently improving its thermal performance by about 22% in comparison to the control pile. Similarly, the magnitude of temperature developed in the pile and surrounding soil were observed to be lower in the pile with PCM. This can ultimately reduce the induced stresses and strains induced in a pile due to heat energy extraction or rejection.
 
 Conclusion
 This paper investigated the feasibility of using salt hydrate PCM in energy piles for heat storage. It was found that the energy rejected in a pile with PCM increases by up to 22% compared to a non-PCM pile.

Coupld thermo-hydraulic modelling of heat storage in an embankment

Coupld thermo-hydraulic modelling of heat storage in an embankment

End‐winding wire‐insulation heat conduction model for precise thermal predictions of permanent magnet synchronous machines

AbstractAccurate thermal calculations of end‐winding temperature rises are the key issue in designing and developing cooling systems of permanent magnet synchronous machines (PMSMs). Due to the complex connections of the end‐windings, it is challenging to precisely predict the heat dissipation capacities through a traditional wire‐insulation equivalent model. Numerical simulations and lumped parameter thermal networks (LPTN) are used by the authors to develop thermal models that illustrate the end‐winding properties of a 2.1‐kW PMSM. As multi‐strand end wires are bent and bound together by ribbons, they have thermal interrelations which can hardly be considered in LPTN models. An equivalent coefficient enhancing the axial heat conduction capacities of end‐windings is proposed for LPTN calculations to model the aforementioned thermal interrelations with circumferential symmetric structures. To correctly model the mutual thermal coupling between various strands of end‐windings, the thermal conductivity of the equivalent insulation sheets between the multi‐strand end‐windings is determined for exact numerical calculations. The external insulation sheet thickness is calculated based on the equivalent thermal conductivity. After developing heat conduction models for LPTN and numerical simulations, LPTN and FEA are used to determine the PMSM's temperature rise characteristics. To verify the approaches, the computation findings are contrasted with experimental ones.

Optimizing Device Performance of Multi-Pass Flat-Plate Solar Air Heaters on Various Recycling Configurations

Various external-recycle configurations of multi-pass flat-plate solar air collectors were studied theoretically to examine the optimal thermal performance under the same working dimension and operation conditions. An absorber plate and insulation sheet were implemented horizontally and vertically, respectively, into an open rectangular conduit to conduct a recycling four-pass operation, which the device lengthens the air flow channel and increases the air mass flow rate within the collector, and thus, a more heat transfer efficiency is obtained. Four recycling types with different external-recycle patterns were introduced and expected to augment the heat transfer rate due to the turbulent convective intensity through four subchannels in the present study. Coupling energy balances into one-dimensional modeling equations were derived by making the energy-flow diagram within a finite element, which the longitudinal temperature distributions for each subchannel were obtained. The theoretical predictions show that the improved four-pass device is accomplished due to the multiple heating pathways over and under the absorber plate, from which the turbulence intensity augmentation results in the heat transfer rate as compared to that in the device without inserting the absorber plate and insulation sheet (say a downward-type single-pass solar air collector). The theoretical results also show that the external-recycle configuration (say Type C in the present study) acts as an optimal collector thermal efficiency and leading to a beneficial design in multi-pass solar air collectors for improving heat-transfer rate and increasing resident time under the same operation conditions. Theoretical predictions show a higher heat-transfer efficiency for the present recycling configurations up to a maximum 115% device enhancement in comparison to that of a single-pass device. Examination of implementing the absorber plate and insulation sheet on the heat-transfer efficiency enhancement as well as the hydraulic dissipated power increment were also delineated, and deliberated the suitable external-recycle configuration with respect to an economic consideration.

Evolution of the Shadow Effect with Film Thickness and Substrate Conductivity on a Hemispherical Workpiece during Magnetron Sputtering

When depositing films on a complex workpiece surface by magnetron sputtering, the shadow effect occurs and causes the columnar structure to tilt toward the substrate owing to the oblique incident angle of the plasma flux, affecting the microstructure and properties of the films. Improving the surface diffusion could alleviate the shadow effect, whereas changing the energy of the deposited particles could improve surface diffusion. Different substrate conductivities could affect the energy of the deposited particles when they reach the substrate. In this study, Si (semiconductor) and SiO2 (insulator) sheets are mounted on the inner surface of a hemispherical workpiece, and Ti films with different thicknesses (adjusted by the deposition time) are deposited on the inner surface of the hemispherical workpiece by direct current magnetron sputtering. The results show that there is a threshold thickness and incident angle before the films are affected by the shadow effect. The threshold could be affected by the film thickness, the incident angle, and the conductivity of the substrate. The threshold would decrease as the film thickness or incidence angle increased or the conductivity of the substrate decreased. When the film thickness or incident angle does not reach the threshold, the film would not be affected by the shadow effect. In addition, the film deposited later would tilt the vertical columnar structure of the film deposited earlier. Owing to the different conductivities, the shadow effect manifest earlier for Ti films deposited on the insulator SiO2 than for films deposited on the semiconductor Si when the film thickness is >500 nm.

Quantum-sized topological insulators/semimetals enable ultrahigh and broadband saturable absorption.

Two-dimensional topological insulators/semimetals have recently attracted much attention. However, quantum-sized topological insulators/semimetals with intrinsic characteristics have never been reported before. Herein, we report the high-yield production of topological insulator (i.e., Bi2Se3 and Sb2Te3) and semimetal (i.e., TiS2) quantum sheets (QSs) with monolayer structures and sub-4 nm lateral sizes. Both linear and nonlinear optical performances of the QSs are investigated. The QS dispersions present remarkable photoluminescence with excitation wavelength-, concentration-, and solvent-dependence. The solution-processed QSs-poly(methyl methacrylate) (PMMA) hybrid thin films demonstrate exceptional nonlinear saturation absorption (NSA). Particularly, Bi2Se3 QSs-PMMA enables record-high NSA performance with a broadband feature. Specifically, the (absolute) modulation depths up to 71.6 and 72.4% and saturation intensities down to 1.52 and 0.49 MW cm-2 are achieved at 532 and 800 nm, respectively. Such a phenomenal NSA performance would greatly facilitate their applications in mode-locked lasers and related fields.

RESEARCH OF PHYSICAL PROCESSES IN LAMINATED MAGNETIC CORES OF ELECTRIC MACHINES

The aim of this work is to use fast-moving processes to detect defects in the inter-sheet insulation of laminated magnetic core of electric machines. Violation of the sheet insulation causes increased eddy currents as a result of increased losses and integrated local overheating in the body of the magnetic core. The article develops a mathematical field model of induction distribution in a toroidal toothed magnetic core of an asynchronous motor series 4AA63V4U3 0.37 kW when superimposed on the back of the core of the power winding powered by a high frequency voltage source in the range. An experimental study of losses in the magnetic coret and the distribution of losses on eddy currents and remagnetization (hysteresis).
 When designing an electric machine, its operating characteristics, optimal operating modes, thermal condition and many other factors are calculated using the nominal values ​​of steel parameters, windings and all materials used in the machine. However, these materials do not always have the stated characteristics and quality. For example, during the manufacture and stamping of electrical steel sheets, it is exposed to a significant level of influence, which in some way affects its characteristics. In addition, even if we assume that during the production of all stages of manufacturing the material came flawlessly, the condition and as a result the parameters of materials and EM in general change during operation as a result of accidents or even simple aging and wear.
 Therefore, given these facts, it becomes clear that during planned or unplanned repairs it makes sense to check the condition of materials, insulation, as their condition depends on the allowable loads, temperature, etc. In particular, the state of the magnetic circuit largely determines the temperature around the conductors in the grooves and as a result determines how long the winding will actually last in contrast to the specified service life and rated power at which to use this EM.
 The concept of the state of the magnetic circuit can be divided into the state of electrical steel and the state of its insulation. The first component changes quite poorly during operation and is generally caused by the "aging" of steel if you do not take into account any serious damage as a result of accidents, but it can be damaged during manufacture. But the second component is significantly affected during operation and significantly determines the quality of the magnetic circuit as a whole.

Iron lamination and interlaminar insulation for high-frequency pulsed magnets.

In high-frequency pulsed magnets, such as kickers in particle accelerators, it is essential to reduce eddy currents that could be induced in the magnet core during excitation not to distort and attenuate the magnetic field pulse. A novel iron lamination scheme with additional interlaminar insulation is proposed for the magnet core of such pulsed magnets. A laminated steel sheet core is formed by alternately stacking thin steel and insulation sheets. For application to matched kicker magnets for accelerators, test magnets with the new and conventional iron lamination were designed, assembled, and extensively evaluated. The pulsed magnetic field waveforms of two test magnets with the new lamination successfully matched to below 0.1% over the entire pulse duration, which was significantly better than those with the conventional lamination. Among the applications of the developed high-frequency pulsed magnets, beam injection kickers for the coming next generation light sources and future colliders, where suppression of the transient stored-beam oscillation during beam injection is crucial, are considered to be promising.

Comparative implementation of graphene sheet insulation heat effect in dry-type transformers

Since the distribution transformers are widely used in industry, many variables, including materials, methods, and manufacturing processes directly affect its lifetime. The dry-type transformers are usually used in inner applications while heat dissipation directly influences the lifetime of a transformer, a significant improvement in this area, will result in further design like using the dry-type transformer in a closed box for outdoor applications. The reduction of the internal temperature of DTT also will conclude the reduction of its size. According to insulation properties of graphene sheet, the contribution of insulation of the winding and core is examined. Since the dry-type transformer uses standard oil-immersed paper insulation, the heat dissipation performance could be improved by addition of graphene sheet material. The results of this study showed that the graphene sheet provided a better heat transfer performance than the standard insulation, with decreases of 13–27% in the winding temperature and 24–37% in the core temperature.

Development of a New Silica Aerogel-Polypropylene Foam Composite as a Highly Flexible Thermal Insulation Material

A new flexible thermal insulation sheet, a composite of silica aerogel with polypropylene (PP) foam, has been developed. Even though a large volume ratio of silica aerogel (97%) was included, the composite showed high flexibility. Thermal conductivity of the composite was 0.016 W/(m⋅K) at 298 K, which is as low as silica aerogel monolith. Silica aerogel flaking, which has been a problem in practical applications, is very low in this composite due to skin layers of the polymer-foam composite. A supercritical drying process for rolled sheets of the material for large-scale production is also described. Simulations of extraction of 2-propanol from a silica alcogel revealed that rolled composite sheets with small spaces between the sheet composite are able to dry in a reasonable extraction time. These findings led to effective on production of this material on a pilot industrial scale.

A floating solar still inspired by continuous root water intake

Floating solar still is considered as a land-saving, easy-operating and environmental-friendly approach for freshwater production. However, the low yield and work instability in actual weather conditions limits its application. To overcome these disadvantages, a bionic floating solar still inspired by water intake of plant roots was presented in this paper. The channels for water supply were distributed in array and wrapped in a whole thermal insulation sheet. With the design of simulating roots, the present desalination system achieves low heat losses, water-absorbing uniformity and structural stability. Cellulose fabric and glass were separately selected as evaporation and condensation materials of the experimental prototype after preliminary test. The outdoor experiment was conducted in Xingtai, China, and the accumulated radiation in the test day was 21.96 MJ/m2. The maximum evaporation temperature and daily freshwater yield reached 59.2 °C and 1.5 kg/m2/d, respectively, which were the highest in comparison with existing floating solar stills. Next, the effect of rolling motion on humid air flow inside the still was investigated by CFD simulation. The results of this study will contribute to the further development of floating solar still, as well as the application of such small-scale desalination technologies.

Physical and mechanical properties of insulation from rubber leave

This research aims to study the insulation sheet of rubber leaves. By testing physical properties and mechanical property at the ratio of rubber leave : rubber latex were 20:80, 30:70, 40:60, 50:50, 60:40, 70:30 and 80:20. Use rubber latex as a binder to allow the material to be bonded. The insulating sheets produced are smooth 16×16×2 cm3. From the results showed that the moisture content of the sample were 6.722 - 14.747%. The tensile strength were 0.0002 – 0.0288 MPa. The fire spread rate were run of 0 - 6.640 mm/min and the ratio of 70:30 and 80:20 were no fire spread rate. Then finally, the heat conductivity coefficient were 0.0283 - 0.0442 W/m·K. Moreover, samples of ratio 80:20 have a better conductivity coefficient than commercial insulation and confirmed with the SEM-EDX analysis.

Measurements of Displacement Cross Section of Tungsten under 389-MeV Proton Irradiation and Thermal Damage Recovery

For validating the number of displacements per atom (dpa) for tungsten under high-energy proton irradiation, we measured displacement cross sections related to defect-induced electrical resistivity changes in a tungsten wire sample under irradiation with 389-MeV protons under 10 K. The Gifford–McMahon cryocooler was used to cool the sample using a conductive coolant via thermal conduction plates of oxygen-free high-conductivity copper and electrical insulation sheets of aluminum nitride ceramic. In this experiment, the displacement cross section was 1612 ± 371 b for tungsten at 389 MeV. A comparison of the experimental displacement cross sections of tungsten with the calculated results obtained using Norgett–Robinson–Torrens (NRT) dpa and athermal recombination-corrected (arc) dpa cross sections indicates that arc-dpa was in better agreement with the experimental data than NRT-dpa; this is similar to the displacement cross sections of copper. From the measurements of damage recovery of the accumulated defects in tungsten through isochronal annealing, which is related to the defect concentration of the sample, approximately 20% of the damage was recovered at 60 K. This trend was similar to those observed in other experimental results for reactor neutrons.

Micro Edge Gas Chamber (MEGC), a novel detector with the same performance as Micro Strip Gas Chamber (MSGC)

The proposed radiation gas detector has a similar structure as the Micro Strip Gas Chamber (MSGC), but with a different manufacturing process. In this detector, the edges of a stacked Cathode (Copper)/Insulator (Mylar)/Anode (Aluminum)/Insulator (Mylar) sheet sequence have the same performance as the MSGC, so it is called the Micro Edge Gas Chamber (MEGC). Since in the production process of MEGC, it is not necessary to deposit the metals on the substrate, the choice of materials is more flexible. In this way, different insulating materials with suitable conductivity and thickness can be used to improve rate capability and multiplication gain, respectively. In addition, without clean room and state-of-the-art technology, it is possible to fabricate MEGC with very primary instruments. For the gas mixture of (Ar: 70%, CO2:30%), for the alpha particles, the maximum amplification gain of fabricated MEGC is 355, and for the signal-to-noise ratio (SNR) of 15, the full detection efficiency of around 98% can be achieved. For the proposed MEGC, the maximum number of charges before electric discharge (primary charges generated in the drift region multiplied by the multiplication gain) is around 1.1 × 107, and for the best-designed MSGC is 4 × 107. Thus, the proposed detector, despite its simplicity, without any optimization, has a reasonable quality with respect to MSGC.

Changing from a Vertical Burr to a Horizontal Burr in the Vertical-Type High-Speed Twin-Roll Caster

Strip casting using a side dam plate produces a vertical burr at the strip edge. In the present study, changing this vertical burr into a horizontal burr using a burr changer is proposed. The burr changer was placed inside the side dam plate. The burr changer was made from mild steel and an insulator sheet and cut along the shape of the roll. The burr changer was placed so as to prevent exhaustion of semisolid metal between the side dam plate and the roll-side surface. When the position of the burr changer was appropriate, the vertical burr changed into a horizontal burr. The horizontal burr was flat. The width of the horizontal burr was affected by the lowest position of the burr changer and became narrower as the lowest position of the burr changer approached the roll gap position.

Solvent-Solvent Correlations across Graphene: The Effect of Image Charges.

Wetting experiments show pure graphene to be weakly hydrophilic, but its contact angle (CA) also reflects the character of the supporting material. Measurements and molecular dynamics simulations on suspended and supported graphene often reveal a CA reduction due to the presence of the supporting substrate. A similar reduction is consistently observed when graphene is wetted from both sides. The effect has been attributed to transparency to molecular interactions across the graphene sheet; however, the possibility of substrate-induced graphene polarization has also been considered. Computer simulations of CA on graphene have so far been determined by ignoring the material's conducting properties. We improve the graphene model by incorporating its conductivity according to the constant applied potential molecular dynamics. Using this method, we compare the wettabilities of suspended graphene and graphene supported by water by measuring the CA of cylindrical water drops on the sheets. The inclusion of graphene conductivity and concomitant polarization effects leads to a lower CA on suspended graphene, but the CA reduction is significantly bigger when the sheets are also wetted from the opposite side. The stronger adhesion is accompanied by a profound change in the correlations among water molecules across the sheet. While partial charges on water molecules interacting across an insulator sheet attract charges of the opposite sign, apparent attraction among like charges is manifested across the conducting graphene. The change is associated with graphene polarization, as the image charges inside the conductor attract equally signed partial charges of water molecules on both sides of the sheet. Additionally, using a nonpolar liquid (diiodomethane), we affirm a detectable wetting translucency when liquid-liquid forces are dominated by dispersive interactions. Our findings are important for predictive modeling toward a variety of applications including sensors, fuel cell membranes, water filtration, and graphene-based electrode materials in high-performance supercapacitors.