scholarly journals Theoretical demonstration of a capacitive rotor for generation of alternating current from mechanical motion

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ehud Haimov ◽  
Aidan Chapman ◽  
Fernando Bresme ◽  
Andrew S. Holmes ◽  
Tom Reddyhoff ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Power Output ◽  
Alternating Current ◽  
Organic Electrolyte ◽  
Small Scale ◽  
Mechanical Motion ◽  
Significant Power ◽  
Energy Harvesters ◽  
Sustainable Economy ◽  
Water Turbines

AbstractInnovative concepts and materials are enabling energy harvesters for slower motion, particularly for personal wearables or portable small-scale applications, hence contributing to a future sustainable economy. Here we propose a principle for a capacitive rotor device and analyze its operation. This device is based on a rotor containing many capacitors in parallel. The rotation of the rotor causes periodic capacitance changes and, when connected to a reservoir-of-charge capacitor, induces alternating current. The properties of this device depend on the lubricating liquid situated between the capacitor’s electrodes, be it a highly polar liquid, organic electrolyte, or ionic liquid – we consider all these scenarios. An advantage of the capacitive rotor is its scalability. Such a lightweight device, weighing tens of grams, can be implemented in a shoe sole, generating a significant power output of the order of Watts. Scaled up, such systems can be used in portable wind or water turbines.

Geometric and Material Optimization of Vortex-Induced Vibration Micro Energy Harvesters for Localized Wind Environments

2012 ◽  
Author(s):  
Jesse J. French ◽  
Colton T. Sheets
Keyword(s):  
Energy Harvesting ◽  
Power Output ◽  
Fluid Velocity ◽  
Frequency Variation ◽  
Vortex Induced Vibration ◽  
Energy Harvesters ◽  
Wind Speeds ◽  
Material Optimization ◽  
Piezoelectric Energy ◽  
Wind Velocities

Wind energy capture in today’s environment is often focused on producing large amounts of power through massive turbines operating at high wind speeds. The device presented by the authors performs on the extreme opposite scale of these large wind turbines. Utilizing vortex induced vibration combined with developed and demonstrated piezoelectric energy harvesting techniques, the device produces power consistent with peer technologies in the rapidly growing field of micro-energy harvesting. Vortex-induced vibrations in the Karman vortex street are the catalyst for energy production of the device. To optimize power output, resonant frequency of the harvester is matched to vortex shedding frequency at a given wind speed, producing a lock-on effect that results in the greatest amplitude of oscillation. The frequency of oscillation is varied by altering the effective spring constant of the device, thereby allowing for “tuning” of the device to specific wind environments. While localized wind conditions are never able to be predicted with absolute certainty, patterns can be established through thorough data collection. Sampling of local wind conditions led to the design and testing of harvesters operating within a range of wind velocities between approximately 4 mph and 25 mph. For the extremities of this range, devices were constructed with resonant frequencies of approximately 17 and 163 Hz. Frequency variation was achieved through altering the material composition and geometry of the energy harvester. Experimentation was performed on harvesters to determine power output at optimized fluid velocity, as well as above and below. Analysis was also conducted on shedding characteristics of the device over the tested range of wind velocities. Computational modeling of the device is performed and compared to experimentally produced data.

Development of Rotary Engine Based Micro-DG/CHP System

2016 ◽  
Author(s):  
Richard L. Hack ◽  
Max R. Venaas ◽  
Vince G. McDonell ◽  
Tod M. Kaneko
Keyword(s):  
Distributed Generation ◽  
Power Output ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Pollutant Emissions ◽  
Small Scale ◽  
Rotary Engine ◽  
Chp System ◽  
Performance Results

Small scale Distributed Generation with waste heat recovery (<50 kW power output, micro-DG/CHP) is an expanding market supporting the widespread deployment of on-site generation to much larger numbers of facilities. The benefits of increased overall thermal efficiency, reduced pollutant emissions, and grid/microgrid support provided by DG/CHP can be maximized with greater quantities of smaller systems that better match the electric and thermal on-site loads. The 3-year CEC funded program to develop a natural gas fueled automotive based rotary engine for micro-DG/CHP, capitalizing upon the unique attributes engine configuration will be presented including initial performance results and plans for the balance of the program.

scholarly journals Organic electrolyte solutions as versatile media for the dissolution and regeneration of cellulose

2017 ◽  
Vol 19 (20) ◽  
pp. 4754-4768 ◽  
Author(s):  
Matthew T. Clough
Keyword(s):  
Ionic Liquid ◽  
Room Temperature ◽  
Electrolyte Solutions ◽  
Room Temperature Ionic Liquid ◽  
Organic Electrolyte

Organic electrolyte solutions – mixtures of a (room-temperature) ionic liquid with a neutral, organic, polar co-solvent – are attracting increasing attention as solvents for the regeneration and derivatisation of cellulose.

scholarly journals A comparison of power output from linear and nonlinear kinetic energy harvesters using real vibration data

2013 ◽  
Vol 22 (7) ◽  
pp. 075022 ◽  
Author(s):  
Stephen P Beeby ◽  
Leran Wang ◽  
Dibin Zhu ◽  
Alex S Weddell ◽  
Geoff V Merrett ◽  
...  
Keyword(s):  
Kinetic Energy ◽  
Power Output ◽  
Energy Harvesters ◽  
Vibration Data ◽  
Linear And Nonlinear ◽  
Nonlinear Kinetic

scholarly journals Fluorinated Polyethylene Propylene Ferroelectrets with an Air-Filled Concentric Tunnel Structure: Preparation, Characterization, and Application in Energy Harvesting

Micromachines ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1072
Author(s):  
Xi Zuo ◽  
Li Chen ◽  
Wenjun Pan ◽  
Xingchen Ma ◽  
Tongqing Yang ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Resonance Frequency ◽  
Power Output ◽  
Energy Harvester ◽  
Vibrational Energy ◽  
Piezoelectric Response ◽  
Tunnel Structure ◽  
Energy Harvesters ◽  
The Earth ◽  
Seismic Mass

Fluorinated polyethylene propylene (FEP) bipolar ferroelectret films with a specifically designed concentric tunnel structure were prepared by means of rigid-template based thermoplastic molding and contact polarization. The properties of the fabricated films, including the piezoelectric response, mechanical property, and thermal stability, were characterized, and two kinds of energy harvesters based on such ferroelectret films, working in 33- and 31-modes respectively, were investigated. The results show that the FEP films exhibit significant longitudinal and radial piezoelectric activities, as well as superior thermal stability. A quasi-static piezoelectric d33 coefficient of up to 5300 pC/N was achieved for the FEP films, and a radial piezoelectric sensitivity of 40,000 pC/N was obtained in a circular film sample with a diameter of 30 mm. Such films were thermally stable at 120 °C after a reduction of 35%. Two types of vibrational energy harvesters working in 33-mode and 31-mode were subsequently designed. The results show that a power output of up to 1 mW was achieved in an energy harvester working in 33-mode at a resonance frequency of 210 Hz, referring to a seismic mass of 33.4 g and an acceleration of 1 g (g is the gravity of the earth). For a device working in 31-mode, a power output of 15 μW was obtained at a relatively low resonance frequency of 26 Hz and a light seismic mass of 1.9 g. Therefore, such concentric tunnel FEP ferroelectric films provide flexible options for designing vibrational energy harvesters working either in 33-mode or 31-mode to adapt to application environments.

scholarly journals Comparative Analysis of Small-Scale Organic Rankine Cycle Systems for Solar Energy Utilisation

Energies ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 829 ◽  
Author(s):  
Ruiqi Wang ◽  
Long Jiang ◽  
Zhiwei Ma ◽  
Abigail Gonzalez-Diaz ◽  
Yaodong Wang ◽  
...  
Keyword(s):  
Solar Energy ◽  
Power Output ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Hot Water ◽  
Superior Performance ◽  
Small Scale ◽  
Water Storage Tank ◽  
Solar Thermal Collector ◽  
Cycle Systems

Small-scale organic Rankine cycle (ORC) systems driven by solar energy are compared in this paper, which aims to explore the potential of power generation for domestic utilisation. A solar thermal collector was used as the heat source for a hot water storage tank. Thermal performance was then evaluated in terms of both the conventional ORC and an ORC using thermal driven pump (TDP). It is established that the solar ORC using TDP has a superior performance to the conventional ORC under most working conditions. Results demonstrate that power output of the ORC using TDP ranges from 72 W to 82 W with the increase of evaporating temperature, which shows an improvement of up to 3.3% at a 100 °C evaporating temperature when compared with the power output of the conventional ORC. Energy and exergy efficiencies of the ORC using TDP increase from 11.3% to 12.6% and from 45.8% to 51.3% when the evaporating temperature increases from 75 °C to 100 °C. The efficiency of the ORC using TDP is improved by up to 3.27%. Additionally, the exergy destruction using TDP can be reduced in the evaporator and condenser. The highest exergy efficiency in the evaporator is 96.9%, an improvement of 62% in comparison with that of the conventional ORC, i.e., 59.9%. Thus, the small-scale solar ORC system using TDP is more promising for household application.

Enhanced thermal energy harvesting performance of a cobalt redox couple in ionic liquid–solvent mixtures

2016 ◽  
Vol 18 (3) ◽  
pp. 1404-1410 ◽  
Author(s):  
Manoj A. Lazar ◽  
Danah Al-Masri ◽  
Douglas R. MacFarlane ◽  
Jennifer M. Pringle
Keyword(s):  
Ionic Liquid ◽  
Energy Harvesting ◽  
Thermal Energy ◽  
Power Output ◽  
Redox Couple ◽  
Solvent Mixtures ◽  
Thermal Energy Harvesting ◽  
Electrolyte Mixture

Significant improvements in thermocell power output have been achieved using a cobalt-based redox couple in an ionic liquid/molecular solvent electrolyte mixture.

Stochastic Dynamics of a Piezoelectric Energy Harvester Subjected to Lévy Flight Excitations

2017 ◽  
Author(s):  
Subramanian Ramakrishnan ◽  
Collin Lambrecht ◽  
Connor Edlund
Keyword(s):  
Power Output ◽  
Stochastic Dynamics ◽  
Duffing Oscillator ◽  
Average Power ◽  
Coupled System ◽  
Random Excitation ◽  
Small Scale ◽  
Vibration Energy Harvesting ◽  
Piezoelectric Energy ◽  
Average Power Output

Vibration energy harvesting seeks to exploit the energy of ambient random vibration for power generation, particularly in small scale devices. Piezoelectric transduction is often used as a conversion mechanism in harvesting and the random excitation is typically modeled as a Brownian stochastic process. However, non-Brownian excitations are of potential interest, particularly in the nonequilibrium regime of harvester dynamics. In this work, we investigate the averaged power output of a generic piezoelectric harvester driven by Brownian as well as (non-Brownian) Lévy stable excitations both in the linear and the Duffing regimes. First, a coupled system of stochastic differential equations that model the electromechanical system are presented. Numerical simulation results (based on the Euler-Maruyama scheme) that show the average power output from the system under Brownian and Lévy excitations are presented for the cases where the mechanical degree of freedom behaves as a linear as well as a Duffing oscillator. The results demonstrate that Lévy excitations result in higher expectation values of harvested power. In particular, increasing the noise intensity leads to significant increase in power output in the Levy case when compared with Brownian excitations.

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