scholarly journals Ferrites and Nanocrystalline Alloys Applied to DC–DC Converters for Renewable Energies

2022 ◽  
Vol 12 (2) ◽  
pp. 709
Author(s):  
Dante Ruiz ◽  
Jorge Ortíz ◽  
Edgar Moreno ◽  
Claudio Fuerte ◽  
Vicente Venegas ◽  
...  
Keyword(s):  
Power Density ◽  
High Performance ◽  
Low Cost ◽  
Research Work ◽  
Design Procedure ◽  
Renewable Energies ◽  
Nanocrystalline Alloys ◽  
Core Material ◽  
The Core ◽  
Technical Specifications

The medium frequency transformer (MFT) with nanocrystalline alloys is quintessential in new DC–DC converters involved in various front-end applications. The center piece to achieve high-performance, efficient MFTs is the core. There are various options of core materials; however, no deep information is available about which material characteristics and design procedure combo are best to get high performance MFTs while operating at maximal power density. To provide new insights about interrelation between the selection of the core material with the compliance technical specifications, differently to other proposals, this research work aims to design and build, with the same methodology, two MFT prototypes at 20 kHz, with nanocrystalline and ferrite cores, to highlight power density, and overall performance and cost, as matching design criteria. As the experimental results show, a nanocrystalline core has the highest power density (36.91 kW/L), designed at 0.8 T to obtain low losses at 20 kHz, achieving an efficiency of 99.7%. The power density in the ferrite MFT is 56.4% lower than in the nanocrystalline MFT. However, regarding construction cost, the ferrite MFT is 46% lower, providing this a trend towards low-cost DC–DC converters. Finally, high power density in MFTs increases the power density of power DC–DC converters, which have relevant applications in fuel cell-supplied systems, renewable energies, electric vehicles, and solid-state transformers.

scholarly journals A Ni(OH)2 nanopetals network for high-performance supercapacitors synthesized by immersing Ni nanofoam in water

2019 ◽  
Vol 10 ◽  
pp. 281-293 ◽  
Author(s):  
Donghui Zheng ◽  
Man Li ◽  
Yongyan Li ◽  
Chunling Qin ◽  
Yichao Wang ◽  
...  
Keyword(s):  
Power Density ◽  
Current Density ◽  
High Performance ◽  
Low Cost ◽  
Electrode Reaction ◽  
Commercial Application ◽  
Ion Diffusion ◽  
Symmetric Supercapacitor ◽  
Red Led ◽  
A Current

Developing a facile and environmentally friendly approach to the synthesis of nanostructured Ni(OH)2 electrodes for high-performance supercapacitor applications is a great challenge. In this work, we report an extremely simple route to prepare a Ni(OH)2 nanopetals network by immersing Ni nanofoam in water. A binder-free composite electrode, consisting of Ni(OH)2 nanopetals network, Ni nanofoam interlayer and Ni-based metallic glass matrix (Ni(OH)2/Ni-NF/MG) with sandwich structure and good flexibility, was designed and finally achieved. Microstructure and morphology of the Ni(OH)2 nanopetals were characterized. It is found that the Ni(OH)2 nanopetals interweave with each other and grow vertically on the surface of Ni nanofoam to form an “ion reservoir”, which facilitates the ion diffusion in the electrode reaction. Electrochemical measurements show that the Ni(OH)2/Ni-NF/MG electrode, after immersion in water for seven days, reveals a high volumetric capacitance of 966.4 F/cm3 at a current density of 0.5 A/cm3. The electrode immersed for five days exhibits an excellent cycling stability (83.7% of the initial capacity after 3000 cycles at a current density of 1 A/cm3). Furthermore, symmetric supercapacitor (SC) devices were assembled using ribbons immersed for seven days and showed a maximum volumetric energy density of ca. 32.7 mWh/cm3 at a power density of 0.8 W/cm3, and of 13.7 mWh/cm3 when the power density was increased to 2 W/cm3. The fully charged SC devices could light up a red LED. The work provides a new idea for the synthesis of nanostructured Ni(OH)2 by a simple approach and ultra-low cost, which largely extends the prospect of commercial application in flexible or wearable devices.

Development of Technologies on Innovative-Simplified Nuclear Power Plant Using High-Efficiency Steam Injector: Part 14—Cooling Characteristics of the Particulate Core Material Debris Accumulated in Horizontal Narrow Gap

2006 ◽  
Author(s):  
Y. Hirao ◽  
G. Su ◽  
K. Sugiyama ◽  
T. Narabayashi ◽  
M. Mori ◽  
...  
Keyword(s):  
Heat Supply ◽  
Nuclear Power ◽  
High Efficiency ◽  
Hot Spot ◽  
Research Work ◽  
Lower Surface ◽  
Injection System ◽  
Core Material ◽  
Metal Debris ◽  
The Core

When LOCA occurs in proposed nuclear reactor systems, the coolability of the core would be kept by the SI core injection system and therefore the probability of the core meltdown is negligible small. In this research work, we make it clear that the coolability of the RPV bottom is secured even if a part of the core should melt and a substantial amount of debris should be deposited on the lower plenum. In this report, we examined experimentally the coolability of the RPV bottom that a Zircaloy-based loose debris layer is deposited on. We set up a heat supply section made by SUS304 on the loose debris layer and measured the heat flux released into the loose debris bed and the temperature at the lower surface of the heat supply section. In addition, we measured the temperature distribution at the bottom of the loose debris bed. It became clear in this study that the coolability depends on the amount of coolant supplied, and the hot spot would not occur when coolant is supplied. Even if a hotspot should occur in the oxidization of loose metal debris accompanied with rapid heat generation. It is found that when a small amount of coolant can be supplied, it disappears because of a high capillary force of oxidized loose debris. So it is confirmed that the soundness of RPV is basically maintained.

SUSTAINABLE ULTRA-HIGH-PERFORMANCE GLASS CONCRETE FOR INFRASTRUCTURES

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Arezki Tagnit-Hamou ◽  
Nancy A. Soliman
Keyword(s):  
High Performance ◽  
Glass Powder ◽  
Mechanical Performance ◽  
High Performance Concrete ◽  
Low Cost ◽  
Research Work ◽  
High Strength ◽  
Quartz Powder ◽  
Ultra High Performance Concrete ◽  
Powder Particles

This paper presents research work on the development of a green type of ultra-high-performance concrete using ground glass powders with different degrees of fineness (UHPGC). This article presents the development of an innovative, low-cost, and sustainable UHPGC through the use of glass powder to replace cement, and quartz powder particles. An UHPGC with a compressive strength (fc) of up to 220 MPa was prepared and its fresh, and mechanical properties were investigated. The test results indicate that the fresh UHPGC properties were improved when the cement and quartz powder were replaced with non-absorptive glass powder particles. The strength improvement can be attributed to the glass powder’s pozzolanicity and to its mechanical performance (very high strength and elastic modulus of glass). A case study of using this UHPGC is presented through the design and construction of a footbridge. Erection of footbridge at University of Sherbrooke Campus using UHPGC is also presented as a full-scale application.

Low-cost high-performance asymmetric supercapacitors based on Co2AlO4@MnO2 nanosheets and Fe3O4 nanoflakes

2016 ◽  
Vol 4 (6) ◽  
pp. 2096-2104 ◽  
Author(s):  
Fei Li ◽  
Hao Chen ◽  
Xiao Ying Liu ◽  
Shi Jin Zhu ◽  
Jia Qi Jia ◽  
...  
Keyword(s):  
Power Density ◽  
High Performance ◽  
Low Cost ◽  
High Energy ◽  
Wearable Electronics ◽  
Asymmetric Supercapacitors ◽  
Power Sources ◽  
Mno2 Nanosheets ◽  
Increasing Demand

The development of portable and wearable electronics has promoted the increasing demand for high-performance power sources with high energy/power density, low cost, lightweight, as well as ultrathin and flexible features.

scholarly journals COMPARISON BETWEEN HAAR AND DAUBECHIES WAVELET TRANSFORMIONS ON FPGA TECHNOLOGY

2014 ◽  
pp. 23-29
Author(s):  
Fatma H. Elfouly ◽  
Mohamed I. Mahmoud ◽  
Moawad I. M. Dessouky ◽  
Salah Deyab
Keyword(s):  
High Performance ◽  
Low Cost ◽  
Audio Signal ◽  
Design Procedure ◽  
Discrete Wavelet ◽  
Analysis Tool ◽  
Daubechies Wavelet ◽  
Daubechies Wavelets ◽  
Real Time Processing ◽  
Practical Applications

Recently, the Field Programmable Gate Array (FPGA) technology offers the potential of designing high performance systems at low cost. The discrete wavelet transform has gained the reputation of being a very effective signal analysis tool for many practical applications. However, due to its computation-intensive nature, current implementation of the transform falls short of meeting real-time processing requirements of most application. The objectives of this paper are implement the Haar and Daubechies wavelets using FPGA technology. In addition, the comparison between the Haar and Daubechies wavelets is investigated. The Bit Error Rat (BER) between the input audio signal and the reconstructed output signal for each wavelet is calculated. It is seen that the BER using Daubechies wavelet techniques is less than Haar wavelet. The design procedure has been explained and designed using the stat-of-art Electronic Design Automation (EDA) tools for system design on FPGA. Simulation, synthesis and implementation on the FPGA target technology has been carried out.

Design Procedure and Performance Analysis of a Microturbine Combustor Working on Biogas for Power Generation

2019 ◽  
Author(s):  
Bahamin Bazooyar ◽  
Hamidreza Gohari Darabkhani
Keyword(s):  
Performance Analysis ◽  
Fossil Fuels ◽  
Low Cost ◽  
Research Work ◽  
Design Procedure ◽  
Gaseous Emissions ◽  
Cfd Modelling ◽  
Gas Combustion ◽  
Natural Gas Combustion ◽  
And Performance

Abstract Design of the combustor is of high priority in microturbine generators (MTG) due to the small and compact configuration of these type of generators and high range of the shaft revolution (normally over 100k rpm). Design process of the MTG components including the micro combustor and turbomachinery also require accurate description of the combustion phenomena, heat transfer, emission level and performance analysis of the system. Design of combustors for renewable fuels such as biogas has several complications including overcoming the lower heating value of the biogas (normally 1/3 of the natural gas), combustion instabilities and corrosion effects of burning these types of fuels. The main benefit of burning a carbon neutral fuel (e.g., biogas), however will be in reducing the carbon emission by avoiding fossil fuels and achieving the environmental targets (e.g., Paris Agreement). The tubular combustors are in the centre of attention in design and operations of the microturbines due to their low cost and the level of emission. This research work presents the design procedure and CFD modelling of a tubular combustor for a biogas burnt microturbine engine assembly. The biogas is generated from anaerobic digestions of agriculture waste and include a 57% and 43% mixture of methane and CO2 respectively. All the combustor parts are designed with empirical and practical equations and dimensions are optimised by CFD simulations. Operation of the combustor is then analysed in terms of its gaseous emissions. Finally, the operation of the new combustor in a closed heat and power cycle was verified and compared with conventional combustor of the microturbine burning diesel fuel, and as a result all the benefits and considerations for the application of biogas in microturbine assembly are carefully remarked and discussed.

scholarly journals Effect of MF-Coated Epoxy Resin Microcapsules on Properties of Waterborne Wood Coating on Basswood

Coatings ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 785 ◽  
Author(s):  
Xiaoxing Yan ◽  
Yijuan Chang
Keyword(s):  
Epoxy Resin ◽  
Mass Fraction ◽  
High Performance ◽  
Impact Resistance ◽  
Color Difference ◽  
Core Material ◽  
Wall Material ◽  
The Core ◽  
Mass Fractions ◽  
The Stability

In this paper, melamine–formaldehyde (MF) was used as the wall material, and epoxy resin was used as the core material to prepare microcapsules. The optical properties, mechanical properties and ageing resistance of waterborne topcoat were investigated by adding different mass fractions of microcapsules into the waterborne topcoat. Through scanning electron microscopy and infrared spectroscopy analysis, the prepared microcapsules of core-wall ratio of 0.50 were more uniform. It was found that when the mass fraction of microcapsules is less than 10.0% and the core–wall ratio is 0.50, the original color difference of the coating can be maintained. With the increase in microcapsule mass fraction, the gloss of the topcoat film gradually decreases. The mass fraction of the microcapsule of 4.0% with the core–wall ratio of 0.50 can maintain the original gloss of 30.0 GU. The topcoat film with the MF-coated epoxy resin microcapsules of the core–wall ratio of 0.50 has high impact resistance, adhesion and hardness. The results showed that the gloss loss and color difference of the coating with the MF-coated epoxy microcapsules were the lowest when the mass fraction of microcapsules was 4.0%, indicating that microcapsules can improve the stability of coating. These results lay a technical foundation for the development and application of high-performance wood coatings.

Novel Honeycomb Glassfiber Mat as the Core of Vacuum Insulation Panel

2014 ◽  
Vol 900 ◽  
pp. 247-250
Author(s):  
Cheng Dong Li ◽  
Zhao Feng Chen
Keyword(s):  
Thermal Insulation ◽  
High Performance ◽  
Three Dimensional ◽  
High Strength ◽  
Glass Wool ◽  
Core Material ◽  
The Core ◽  
Vacuum Insulation ◽  
Novel Structure ◽  
Chopped Strand Mat

Vacuum insulation panels (VIPs) are regarded as one of the most promising high-performance thermal insulation solutions on the market today. In this paper, a novel structure, i.e., honeycomb glassfiber mat was proposed as the core material of VIP. The honeycomb glassfiber mat was composed of glass wool mat and glassfiber chopped strand mat. Among them, 70% centrifugal glass wool and 30% flame attenuated glass wool were mixed together to form the 0.5mm-thickness glass wool mat, while thirteen holes with diameter of 10mm were opened uniformly on the surface of glassfiber chopped strand mat. Glassfiber VIPs possessed honeycomb core material have superior thermal conductivity of 1.52mW/(m•K). In order to obtain better thermal insulation performance, ultrafine and stiff fibers with three-dimensional overlapping structure is preferable. Meanwhile, hollow fibers with bifurcated structure are the guarantee of high-strength core material.

scholarly journals Design and Optimization of an Efficient (96.1%) and Compact (2 kW/dm3) Bidirectional Isolated Single-Phase Dual Active Bridge Ac–Dc Converter

2016 ◽  
Author(s):  
Jordi Everts
Keyword(s):  
Power Density ◽  
High Performance ◽  
Single Phase ◽  
Design Procedure ◽  
Cost Effective ◽  
Development Trend ◽  
Single Stage ◽  
Design And Optimization ◽  
Dual Active Bridge ◽  
Conversion Stage

The growing attention for plug-in electric vehicles, and the associated high-performance demands, have initiated a development trend towards highly efficient and compact on-board battery chargers. These isolated ac-dc converters are most commonly realized using two conversion stages, combining a non-isolated power factor correction (PFC) rectifier with an isolated dc-dc converter. This, however, involves two loss stages and a relatively high component count, limiting the achievable efficiency and power density and resulting in high costs. In this paper a single-stage converter approach is analyzed to realize a single-phase ac-dc converter, combining all functionalities into one conversion stage and thus enabling a cost-effective efficiency and power density increase. The converter topology consists of a quasi-lossless synchronous rectifier followed by an isolated dual active bridge (DAB) dc-dc converter, putting a small filter capacitor in between. To show the performance potential of this bidirectional, isolated ac-dc converter, a comprehensive design procedure and multi-objective optimization with respect to efficiency and power density is presented, using detailed loss and volume models. The models and procedures are verified by a 3.7 kW hardware demonstrator, interfacing a 400 V dc-bus with the single-phase 230 V, 50 Hz utility grid. Measurement results indicate a state-of-the-art efficiency of 96.1% and power density of 2.2 kW/dm3, confirming the competitiveness of the investigated single-stage DAB ac-dc converter.

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