scholarly journals Numerical Evaluation and Experimental Test on a New Giant Magnetostrictive Transducer with Low Heat Loss Design

Micromachines ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1397
Author(s):  
Zhuan Bai ◽  
Zonghe Zhang ◽  
Ju Wang ◽  
Xiaoqing Sun ◽  
Wei Hu
Keyword(s):  
Heat Loss ◽  
Temperature Rise ◽  
Magnetic Energy ◽  
Mechanical Energy ◽  
Electric Energy ◽  
Energy Utilization ◽  
Element Analysis ◽  
Excessive Heat ◽  
Excitation Coil ◽  
Magnetostrictive Transducer

Giant magnetostrictive transducer with micro and nano precision has a wide application prospect in the field of remote sensing. However, excessive heat loss of components could generate during the energy conversion and transfer from electric energy to magnetic energy, and magnetic energy to mechanical energy, thereby affecting its long-term service and also reducing energy utilization. In this paper, a new magnetostrictive transducer is proposed and its excitation coil, internal and external magnetic circuit are optimized from the perspective of reducing heat loss. With the help of theoretical and finite element analysis, the response law between key parameters and heat loss of key components are summarized, which provides a basis for reducing heat loss. Finally, according to the optimization scheme, the prototype is processed, and the temperature rise and dynamic output performance of the transducer are tested by constructing an experimental setup. The results show that the transducer has a low temperature rise and good frequency response characteristics, which can provide support for long-time precise actuation on-orbit.

A non-affine electro-viscoelastic microsphere model for dielectric elastomers: Application to VHB 4910 based actuators

2016 ◽  
Vol 28 (5) ◽  
pp. 627-639 ◽  
Author(s):  
Sara Thylander ◽  
Andreas Menzel ◽  
Matti Ristinmaa
Keyword(s):  
Constitutive Model ◽  
Viscoelastic Properties ◽  
Mechanical Energy ◽  
Electric Energy ◽  
Time Dependent ◽  
Dielectric Elastomers ◽  
Element Analysis ◽  
Time Dependent Behaviour ◽  
Macroscopic Continuum ◽  
Dependent Behaviour

Dielectric elastomers belong to a larger group of materials, the so-called electroactive polymers, which have the capability of transforming electric energy to mechanical energy through deformation. VHB 4910 is one of the most popular materials for applications of dielectric elastomers and therefore one of the most investigated. This paper includes a new micromechanically motivated constitutive model for dielectric elastomers that incorporates the nearly incompressible and viscous time-dependent behaviour often found in this type of material. A non-affine microsphere framework is used to transform the microscopic constitutive model to a macroscopic continuum counterpart. Furthermore the model is calibrated, through both homogeneous deformation examples and more complex finite element analysis, to VHB 4910. The model is able to capture both the purely elastic, the viscoelastic and the electro-viscoelastic properties of the elastomer and demonstrates the power and applicability of the electromechanically coupled microsphere framework.

scholarly journals Hydrodynamic constraints on the energy efficiency of droplet electricity generators

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Antoine Riaud ◽  
Cui Wang ◽  
Jia Zhou ◽  
Wanghuai Xu ◽  
Zuankai Wang
Keyword(s):  
Energy Efficiency ◽  
Kinetic Energy ◽  
Total Energy ◽  
Viscous Dissipation ◽  
Shear Force ◽  
Mechanical Energy ◽  
Electric Energy ◽  
The Past ◽  
Viscous Shear ◽  
Impingement Velocity

AbstractElectric energy generation from falling droplets has seen a hundred-fold rise in efficiency over the past few years. However, even these newest devices can only extract a small portion of the droplet energy. In this paper, we theoretically investigate the contributions of hydrodynamic and electric losses in limiting the efficiency of droplet electricity generators (DEG). We restrict our analysis to cases where the droplet contacts the electrode at maximum spread, which was observed to maximize the DEG efficiency. Herein, the electro-mechanical energy conversion occurs during the recoil that immediately follows droplet impact. We then identify three limits on existing droplet electric generators: (i) the impingement velocity is limited in order to maintain the droplet integrity; (ii) much of droplet mechanical energy is squandered in overcoming viscous shear force with the substrate; (iii) insufficient electrical charge of the substrate. Of all these effects, we found that up to 83% of the total energy available was lost by viscous dissipation during spreading. Minimizing this loss by using cascaded DEG devices to reduce the droplet kinetic energy may increase future devices efficiency beyond 10%.

Thermo-Mechanical Modeling and Analysis of Equal Channel Angular Pressing

2005 ◽  
Vol 23 ◽  
pp. 263-266 ◽  
Author(s):  
Qing Xiang Pei ◽  
B.H. Hu ◽  
C. Lu
Keyword(s):  
Equal Channel Angular Pressing ◽  
Temperature Rise ◽  
Flow Behavior ◽  
Material Model ◽  
Workpiece Material ◽  
Element Analysis ◽  
Modeling And Analysis ◽  
Die Geometry ◽  
Angular Pressing ◽  
Good Agreement

Thermo-mechanical finite element analysis was carried out to study the deformation behavior and temperature distribution during equal channel angular pressing (ECAP). The material model used is the Johnson-Cook constitution model that can consider the multiplication effect of strain, strain rate, and temperature on the flow stress. The effects of pressing speed, pressing temperature, workpiece material and die geometry on the temperature rise and flow behavior during ECAP process were investigated. The simulated temperature rise due to deformation heating was compared with published experimental results and a good agreement was obtained. Among the various die geometries studied, the two-turn die with 0° round corner generates the highest and most uniform plastic strain in the workpiece.

Crack Growth Prediction and Leakage Potential of Steam Generator Tubes Subjected to Flow Induced Vibrations

2014 ◽  
Author(s):  
Salim El Bouzidi ◽  
Marwan Hassan ◽  
Jovica Riznic
Keyword(s):  
Crack Growth ◽  
Steam Generator ◽  
Power Plants ◽  
Mechanical Energy ◽  
Steam Generators ◽  
Two Phase ◽  
Element Analysis ◽  
Wide Range ◽  
Flow Induced Vibrations ◽  
Crack Growth Model

Nuclear steam generators are critical components of nuclear power plants. Flow-Induced Vibrations (FIV) are a major threat to the operation of nuclear steam generators. The two main manifestations of FIV in heat exchangers are turbulence and fluidelastic instability, which would add mechanical energy to the system resulting in great levels of vibrations. The consequences on the operation of steam generators are premature wear of the tubes, as well as development of cracks that may leak radioactive heavy water. This paper investigates the effect of tube support clearance on crack propagation. A crack growth model is used to simulate the growth of Surface Flaws and Through-Wall Cracks of various initial sizes due to a wide range of support clearances. Leakage rates are predicted using a two-phase flow leakage model. Non-linear finite element analysis is used to simulate a full U-bend subjected to fluidelastic and turbulence forces. Monte Carlo Simulations are then used to conduct a probabilistic assessment of steam generator life due to crack development.

Simulation and Analysis of Cryogenic Air Separation Process with LNG Cold Energy Utilization

2014 ◽  
Vol 881-883 ◽  
pp. 653-658 ◽  
Author(s):  
Yong Qiang Xiong ◽  
Ben Hua
Keyword(s):  
Energy Consumption ◽  
Liquid Nitrogen ◽  
Electric Energy ◽  
Separation Process ◽  
Air Separation ◽  
Energy Utilization ◽  
Utilization Efficiency ◽  
Pure Oxygen ◽  
Pure Nitrogen ◽  
Cold Energy

In this paper, a cryogenic air separation process with LNG cold energy utilization is proposed to produce liquid nitrogen and high pressure pure oxygen gas economically. To reduce the electric energy consumption of air separation products, liquid nitrogen have been produced by condensing the separated pure nitrogen gas with LNG cold energy utilization, and the recycled nitrogen is served to transfer cold energy from LNG stream to cool off air stream in the proposed cryogenic air separation process. The specifications of streams and the major equipments of the air separation process are simulated with Aspen Plus software and the main parameters analysis are performed. The results show that the energy consumption of the proposed air separation process with LNG cold energy utilization decreased about 58.2% compared with a conventional cryogenic air separation process. The compressed pressure of recycled nitrogen has a big impact on the cost of air separation products and utilization efficiency of LNG cold energy. The LNG cold energy could be fully utilized when the recycled nitrogen has been compressed to above 6.5MPa.

TINJAUAN SINGKAT OPTIMALISASI PEMANFAATAN ENERGI SURYA PADA SEKTOR RUMAH TANGGA

2021 ◽  
Vol 4 (2) ◽  
Author(s):  
Ligan Budi Pratomo ◽  
Nazaruddin Sinaga
Keyword(s):  
Renewable Energy ◽  
Solar Energy ◽  
Energy Use ◽  
Solar Power ◽  
Renewable Energy Sources ◽  
Electric Energy ◽  
Energy Utilization ◽  
Fossil Energy ◽  
Household Sector ◽  
The Government

Energy use always increases, especially fossil energy. Through the National Energy Policy, the government continues to strive to increase the role of new and renewable energy sources so as to reduce dependence on fossil energy. Solar power generation is a type of renewable energy generator that capable to convert solar energy to electric energy. The main components of solar power generatios are batteries, solar panels, charger controllers, and inverters.  Solar power generations technology itself is always being developed, such as automatic monitoring and sun tracking systems designed to improve system performance. One of the applications of solar power generations is in the household sector. In this sector consumes 49% of the national electricity energy in 2018. This type of generator is categorized as a roof solar power generations. Based on existing data, there were 1400  roof solar power generations users in September 2019. The development of solar energy utilization for the household sector is very appropriate because it can help achieve renewable energy about 23% in 2025 and 31% in 2050 in the national energy mix.

scholarly journals Room temperature giant magnetostriction in single-crystal nickel nanowires

2019 ◽  
Vol 11 (1) ◽  
Author(s):  
Anastasios Pateras ◽  
Ross Harder ◽  
Sohini Manna ◽  
Boris Kiefer ◽  
Richard L. Sandberg ◽  
...  
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Single Crystal ◽  
Room Temperature ◽  
Magnetic Energy ◽  
Mechanical Energy ◽  
Three Dimensional ◽  
Local Strain ◽  
Nickel Nanowires ◽  
Giant Magnetostriction

Abstract Magnetostriction is the emergence of a mechanical deformation induced by an external magnetic field. The conversion of magnetic energy into mechanical energy via magnetostriction at the nanoscale is the basis of many electromechanical systems such as sensors, transducers, actuators, and energy harvesters. However, cryogenic temperatures and large magnetic fields are often required to drive the magnetostriction in such systems, rendering this approach energetically inefficient and impractical for room-temperature device applications. Here, we report the experimental observation of giant magnetostriction in single-crystal nickel nanowires at room temperature. We determined the average values of the magnetostrictive constants of a Ni nanowire from the shifts of the measured diffraction patterns using the 002 and 111 Bragg reflections. At an applied magnetic field of 600 Oe, the magnetostrictive constants have values of λ100 = −0.161% and λ111 = −0.067%, two orders of magnitude larger than those in bulk nickel. Using Bragg coherent diffraction imaging (BCDI), we obtained the three-dimensional strain distribution inside the Ni nanowire, revealing nucleation of local strain fields at two different values of the external magnetic field. Our analysis indicates that the enhancement of the magnetostriction coefficients is mainly due to the increases in the shape, surface-induced, and stress-induced anisotropies, which facilitate magnetization along the nanowire axis and increase the total magnetoelastic energy of the system.

scholarly journals Comparison of Two Single Stage Low-Pressure Rotary Lobe Expander Geometries in Terms of Operation

Energies ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 4512
Author(s):  
Michalina Kurkus-Gruszecka ◽  
Piotr Krawczyk
Keyword(s):  
Cfd Simulation ◽  
Mechanical Energy ◽  
Electric Energy ◽  
Low Pressure ◽  
Single Stage ◽  
Small Scale ◽  
Operational Parameters ◽  
Data Simulation ◽  
Time Step ◽  
Geometry Model

In the article the computational fluid dynamics (CFD) simulation and calculated operational parameters of the single stage low-pressure rotary lobe expander compared with the values obtained from a different geometry simulation are presented. Low-pressure rotary lobe expanders are rotary engines that use a compressed gas to produce mechanical energy, which in turn can be converted into another form, i.e., electric energy. Currently, expanders are used in narrow areas, but have a large potential in the energy production from gases of low thermodynamic parameters. The first geometry model was designed on the basis of an industrial device and validated with the empirical data. Simulation of the second geometry was made based on a validated model in order to estimate the operational parameters of the device. The CFD model included the transient simulation of compressible fluid in the geometry changing over time and the rotors motion around two rotation axes. The numerical model was implemented in ANSYS CFX software. After obtaining simulation results in the form of parameters monitors for each time step, a number of calculations were performed using a written code analysing the CFD program output files. The article presents the calculation results and the geometries comparison in terms of work efficiency. The research indicated that the construction of the device on a small scale could cause a significant decrease in the aforementioned parameter, caused by medium leaks in the expander clearances.

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