scholarly journals Influence of attack angle on vortex-induced vibration and energy harvesting of two cylinders in side-by-side arrangement

2019 ◽  
Vol 11 (1) ◽  
pp. 168781401882259
Author(s):  
Li Zhang ◽  
Xinru Mao ◽  
Lin Ding
Keyword(s):  
Energy Harvesting ◽  
Energy Conversion ◽  
Energy Conversion Efficiency ◽  
Maximum Energy ◽  
Attack Angle ◽  
Navier Stokes ◽  
Vortex Induced Vibration ◽  
Hydrokinetic Energy ◽  
Wake Patterns ◽  
Vibration Responses

The vortex-induced vibration and energy harvesting of two cylinders in side-by-side arrangement with different attack angles are numerically investigated using two-dimensional unsteady Reynolds-Averaged Navier–Stokes simulations. The Reynolds number ranges from 1000 to 10,000, and the attack angle of free flow is varied from 0° to 90°. Results indicate that the vortex-induced vibration responses with attack angle range of 0°≤  α ≤ 30° are stronger than other attack angle cases. The parallel vortex streets are clearly observed with synchronized vortex shedding. Relatively large attack angle leads to a phase difference between the wake patterns of the two cylinders. Hydrokinetic energy can be obviously harvested when Re > 4000. Compared with the larger attack angle case, the two side-by-side cylinders with smaller attack angle have better performance on energy conversion. The maximum energy conversion efficiency of 21.7% is achieved. The optimum region for energy conversion is 5000 ≤  Re ≤ 7000 and 0°≤  α ≤ 30°.

scholarly journals The Effects of Reynolds Number on Energy Harvesting from FIV by a Square Cylinder

2020 ◽  
Vol 38 (5) ◽  
pp. 928-936
Author(s):  
Peng Han ◽  
Guang Pan ◽  
Qiaogao Huang ◽  
Yao SHI
Keyword(s):  
Reynolds Number ◽  
Energy Harvesting ◽  
Energy Conversion ◽  
Reynolds Numbers ◽  
Energy Conversion Efficiency ◽  
Published Data ◽  
Square Cylinder ◽  
A Value ◽  
Vibration Responses ◽  
Intense Vibration

Under the action of incoming flow, the square cylinder can generate more intense vibration responses than the circular cylinder, which is beneficial for energy harvesting. Numerical simulations for FIV of the square-cylinder energy conversion system are carried out. URANS equations are used in conjunction with the shear stress transport k-ω turbulence model to predict the flow, and the equations for vibrations are solved by the Newmark-β algorithm. The present numerical method is validated against the published data with good consistency. The Reduced velocity Ur is varied from 1-20, with corresponding Reynolds numbers of 24 000-160 000. The numerical results indicate that the Reynolds number significantly affects the frequency response, amplitude response, vortex shedding mode, and energy conversion efficiency. The highest efficiency point locates at Re=88 000, with a value of 7.156%. When Re>120 000, the system transits from vortex-induced vibration into galloping, and its vibration responses as well as energy harvesting characteristics change sharply. Fully developed galloping motion occurs when Re>144 000.

scholarly journals Dielectric elastomer generator with diaphragm configuration

2018 ◽  
Vol 192 ◽  
pp. 01032
Author(s):  
Zhen-Qiang Song ◽  
Sriyuttakrai Sathin ◽  
Wei Li ◽  
Kazuhiro Ohyama ◽  
ShiJie Zhu
Keyword(s):  
Energy Density ◽  
Energy Conversion ◽  
Conversion Efficiency ◽  
Energy Conversion Efficiency ◽  
Dielectric Elastomer ◽  
Maximum Energy ◽  
Constant Voltage ◽  
Low Viscosity ◽  
65 J ◽  
Low Efficiency

The dielectric elastomer generator (VHB 4905, 3M) with diaphragm configuration was investigated with the constant-voltage harvesting scheme in order to investigate its energy harvesting ability. The maximum energy density and energy conversion efficiency is measured to be 65 J/kg and 5.7%, respectively. The relatively low efficiency indicates that higher energy conversion efficiency is impeded by the viscosity of the acrylic elastomer, suggesting that higher conversion efficiency with new low-viscosity elastomer should be available.

Energy conversion efficiency of thermoelectric power generators with cylindrical legs

2021 ◽  
pp. 1-23
Author(s):  
Dandan Pang ◽  
Aibing Zhang ◽  
Zhenfei Wen ◽  
Baolin Wang ◽  
Ji Wang
Keyword(s):  
Theoretical Model ◽  
Impact Factor ◽  
Energy Conversion ◽  
Conversion Efficiency ◽  
Heat Sink ◽  
Energy Conversion Efficiency ◽  
Maximum Energy ◽  
Factor H ◽  
Heat Convection ◽  
Power Generators

Abstract Thermoelectric power generators (TEGs) have been attracted increasing attention recently due to their capability of converting waste heat into useful electric energy without hazardous emissions. This paper develops a theoretical model to analyze the thermoelectric performance of TEGs with cylindrical legs. The influence of heat convection loss between lateral surfaces of thermoelectric legs and ambient environment on the energy conversion efficiency is investigated. For the idealized model, closed-form solutions of optimal electric current, maximum power output and maximum energy conversion efficiency are obtained, a new dimensionless impact factor H is introduced to capture the heat convection effect. The impact factor H depends on the ratio of heat conductivity to heat convection coefficient and geometry size of thermoelectric legs, as well as the temperature ratio of heat sink to hot source. The performance can be evaluated by the figure of merit, impact factor H and temperature gradient across the hot source and heat sink for a well-designed TEG with cylindrical legs. For the case of considering contact resistance, it is found that there exists an optimal leg's height for maximum energy conversion efficiency due to the heat convection on lateral surfaces of thermoelectric leg. The proposed theoretical model in this paper will be very helpful in the designing of actual TEG devices.

scholarly journals Analysis and optimal design of a vibration isolation system combined with electromagnetic energy harvester

2019 ◽  
Vol 30 (16) ◽  
pp. 2382-2395
Author(s):  
Uchenna Diala ◽  
SM Mahdi Mofidian ◽  
Zi-Qiang Lang ◽  
Hamzeh Bardaweel
Keyword(s):  
Energy Harvesting ◽  
Energy Conversion ◽  
Conversion Efficiency ◽  
Vibration Isolation ◽  
Energy Conversion Efficiency ◽  
Isolation System ◽  
Magnetic Components ◽  
Energy Harvesting System ◽  
Response Function Method ◽  
Conversion Efficiencies

This work investigates a vibration isolation energy harvesting system and studies its design to achieve an optimal performance. The system uses a combination of elastic and magnetic components to facilitate its dual functionality. A prototype of the vibration isolation energy harvesting device is fabricated and examined experimentally. A mathematical model is developed using first principle and analyzed using the output frequency response function method. Results from model analysis show an excellent agreement with experiment. Since any vibration isolation energy harvesting system is required to perform two functions simultaneously, optimization of the system is carried out to maximize energy conversion efficiency without jeopardizing the system’s vibration isolation performance. To the knowledge of the authors, this work is the first effort to tackle the issue of simultaneous vibration isolation energy harvesting using an analytical approach. Explicit analytical relationships describing the vibration isolation energy harvesting system transmissibility and energy conversion efficiency are developed. Results exhibit a maximum attainable energy conversion efficiency in the order of 1%. Results suggest that for low acceleration levels, lower damping values are favorable and yield higher conversion efficiencies and improved vibration isolation characteristics. At higher acceleration, there is a trade-off where lower damping values worsen vibration isolation but yield higher conversion efficiencies.

scholarly journals Fabrication of Norbixin-Sensitized Solar Cell and The Effect of Light Intensity on Its Performance and Reusability

2021 ◽  
Vol 926 (1) ◽  
pp. 012091
Author(s):  
W Rahmalia ◽  
E Crespo ◽  
T Usman
Keyword(s):  
Solar Cell ◽  
Light Intensity ◽  
Energy Conversion ◽  
Conversion Efficiency ◽  
Performance Test ◽  
Energy Conversion Efficiency ◽  
Ester Group ◽  
Maximum Energy ◽  
Dye Sensitized ◽  
Uv Visible

Abstract Dye-sensitized solar cell (DSSC) is a third-generation solar cell that has been developed as one of the clean and renewable alternative energies. This study aims to fabricate norbixin-sensitized solar cell (NSSC). Norbixin was obtained from the saponification followed by acidification of bixin and characterized using UV-Visible and FTIR spectroscopy. The solar cell was assembled using anatase-TiO2 semiconductor, KI/I2/MPII in acetonitrile as the electrolyte, and a platinum paste-based cathode. The UV-Visible spectrophotometry analysis results showed three peaks of carotenoid characteristics at 434, 457, and 486 nm. The formation of norbixin was proved by the absence of a spectral peak for the C-O-C ester group of bixin at 1254 dan 1159 cm-1” The cells performance test showed that the maximum energy conversion efficiency of NSSC increased with increasing light intensity up to 0.08 W/cm2. Exposure to the light above this intensity causes a decrease in the maximum energy conversion efficiency due to the temperature factor. The data also showed that the cell assembled was reusable. It still showed relatively good performance until the third day of analysis.

Maximum Energy-Efficiency Compliant Mechanism Design for Piezoelectric Stack Actuators

Aerospace ◽  
2003 ◽  
Author(s):  
Mostafa M. Abdalla ◽  
Mary Frecker ◽  
Zafer Gu¨rdal ◽  
Terrence Johnson ◽  
Douglas K. Lindner
Keyword(s):  
Energy Efficiency ◽  
Energy Conversion ◽  
Conversion Efficiency ◽  
Compliant Mechanism ◽  
Mechanical Energy ◽  
Electric Energy ◽  
Energy Conversion Efficiency ◽  
Maximum Energy ◽  
System Level ◽  
Voltage Source

Combined optimization of a compliant mechanism and a piezoelectric stack actuator for maximum energy conversion efficiency is considered. The paper presents a system level analysis in which the actuator and the compliant mechanism are mathematically described as linear two-port systems. The combination of stack and compliant mechanism is used to drive a structure, modeled as a mass-spring system. The analysis assumes all components to be free from dissipation, and the piezoelectric stack is driven by an ideal voltage source. Energy conversion efficiency is defined as the ratio of the output mechanical energy to the input electric energy. Theoretical bounds on the system efficiency are obtained. It is shown that the stack actuator can be optimized separately and matched to the specified structure and an optimally designed complaint mechanism. The optimization problem for the compliant mechanism is formulated to maximize a weighted objective function of energy efficiency and stroke amplification. Optimization results are presented for ground structures modeled using frame elements.

scholarly journals Significant Influence of Annealing Temperature and Thickness of Electrode on Energy Conversion Efficiency of Dye Sensitized Solar Cell: Effect of Catalyst

2014 ◽  
Vol 39 ◽  
pp. 78-87 ◽  
Author(s):  
Jasim Uddin ◽  
Jahid M.M. Islam ◽  
Shauk M.M. Khan ◽  
Enamul Hoque ◽  
Mubarak A. Khan
Keyword(s):  
Solar Cell ◽  
Energy Conversion ◽  
Conversion Efficiency ◽  
Annealing Temperature ◽  
High Efficiency ◽  
Energy Conversion Efficiency ◽  
Maximum Energy ◽  
Dye Sensitized Solar Cell ◽  
Great Promise ◽  
Dye Sensitized

Dye sensitized solar cell (DSSC) shows great promise as an alternative to conventional p-n junction solar cells due to their low fabrication cost and reasonably high efficiency. DSSC was assembled by using natural dye extracted from red amaranth (Amaranthus Gangeticus) as a sensitizer and different catalysts for counter electrode were applied for maximum energy conversion efficiency. Annealing temperature and thickness of electrode were also investigated and optimized. Catalyst, annealing temperature and thickness were optimized by the determination of cell performance considering photoelectrochemical output and measuring current and voltage; then calculating efficiency and other electrical parameters. The experimental results indicated that samples having 40 µm electrode thickness and prepared at 450 °C annealing temperature showed the best performance

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