Miniaturized Generators, Volume II

A special issue of Micromachines (ISSN 2072-666X). This special issue belongs to the section "A:Physics".

Deadline for manuscript submissions: closed (31 October 2021) | Viewed by 7790

Special Issue Editor


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Guest Editor
Department of Mechanical Engineering and Mechatronics, Ariel University, Ariel 40700, Israel
Interests: analog electronic design; ultra-low noise systems and sensors; magneto-electric sensors; magneto-optical sensors; system design using computer aided design software; modeling and emulation of the physical processes; precision motion control and positioning; power system analysis and design; RF and Terahertz system design; THz vision systems; VLSI; MEMS; micro-robots; active cooling systems using Peltier effect; thermoelectric power generation; control systems; energy harvesting
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Special Issue Information

Dear Colleagues,

Miniaturized, small-size, down-scalable, on-chip, etc. generators are a relatively new field of research, and such products are more exotic, rather than popular, at this stage. However, the demand for such generators is growing at a rapid pace today. On land, in the ocean, and in space, there are already plenty of high-tech appliances with low and ultra-low power consumption which require long-term autonomous power sources. Smart networks are currently under development and anticipated to become widespread in the near future, and they consist of thousands of sensors that interact with each other and must work off-grid. In this Special Issue, we would like to discuss the diversity and potential of the existing energy sources suitable for conversion into electricity on a low power scale and the transducers for such energy conversion. Of particular interest are mini-generators using renewable energy. This issue’s scope includes electrostatic, electromagnetic, piezoelectric, thermoelectric, micromechanical, fuel-cell, photoelectric, and other generators using acoustic vibrations, waste heat, radioisotope heat, chemical reactions, and solar or artificial light, etc., as a source of energy. Miniaturized generators, on-chip generators, MEMS, or potentially down-scalable to miniature-size generators are also of interest. Of no less interest are applications of miniaturized generators, such as battery replacements in wireless sensors, self-powered chips, applications for smart networks, etc. We invite researchers, scientists, inventors, and engineers to participate in this Special Issue. We are interested in research articles, comments, and reviews on the topics of physical potential, possible topologies, methods of analysis, mathematical modeling, and various ways of producing miniaturized generators.

Dr. Simon Lineykin
Guest Editor

Manuscript Submission Information

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Keywords

  • On-chip generators
  • Miniaturized generators
  • Low-power generators
  • MEMS-based generators
  • Battery replacements for wireless sensors

Published Papers (3 papers)

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Research

15 pages, 5100 KiB  
Article
Edge Cooling of a Fuel Cell during Aerial Missions by Ambient Air
by Lev Zakhvatkin, Alex Schechter, Eilam Buri and Idit Avrahami
Micromachines 2021, 12(11), 1432; https://doi.org/10.3390/mi12111432 - 21 Nov 2021
Cited by 5 | Viewed by 1909
Abstract
During aerial missions of fuel-cell (FC) powered drones, the option of FC edge cooling may improve FC performance and durability. Here we describe an edge cooling approach for fixed-wing FC-powered drones by removing FC heat using the ambient air during flight. A set [...] Read more.
During aerial missions of fuel-cell (FC) powered drones, the option of FC edge cooling may improve FC performance and durability. Here we describe an edge cooling approach for fixed-wing FC-powered drones by removing FC heat using the ambient air during flight. A set of experiments in a wind tunnel and numerical simulations were performed to examine the efficiency of FC edge cooling at various flight altitudes and cruise speeds. The experiments were used to validate the numerical model and prove the feasibility of the proposed method. The first simulation duplicated the geometry of the experimental setup and boundary conditions. The calculated temperatures of the stack were in good agreement with those of the experiments (within ±2 °C error). After validation, numerical models of a drone’s fuselage in ambient air with different radiator locations and at different flight speeds (10–30 m/s) and altitudes (up to 5 km) were examined. It was concluded that onboard FC edge cooling by ambient air may be applicable for velocities higher than 10 m/s. Despite the low pressure, density, and Cp of air at high altitudes, heat removal is significantly increased with altitude at all power and velocity conditions due to lower air temperature. Full article
(This article belongs to the Special Issue Miniaturized Generators, Volume II)
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16 pages, 6774 KiB  
Article
Analysis, Modeling, and Simulation of Thin-Film Cells-Based Photovoltaic Generator Combined with Multilayer Thermoelectric Generator
by Yasir Musa Dakwar, Simon Lineykin and Moshe Sitbon
Micromachines 2021, 12(11), 1342; https://doi.org/10.3390/mi12111342 - 31 Oct 2021
Cited by 1 | Viewed by 1776
Abstract
A new model for a multi-stage thermoelectric generator (TEG) is developed. An electrical and thermal model is built and simulated for different configurations of photovoltaic (PV) stand-alone hybrid systems, combining different stages of a TEG. The approach is evaluated with and without cooling [...] Read more.
A new model for a multi-stage thermoelectric generator (TEG) is developed. An electrical and thermal model is built and simulated for different configurations of photovoltaic (PV) stand-alone hybrid systems, combining different stages of a TEG. The approach is evaluated with and without cooling by coupling a cold plate to a multi-stage hybrid PVTEG system. The model can be adjusted by sizing and specifying the influence of stage number on the overall produced power. Amorphous silicon thin-film (a-Si) is less affected by rising temperature compared to other technology. Hence, it was chosen for evaluating the lower limit gain in a hybrid system under various ambient temperatures and irradiances. The dynamics of the PVTEG system are presented under different coolant water flow rates. Finally, comparative electrical efficiency in reference to PV stand-alone was found to be 99.2% for PVTEG without cooling, 113.5% for PVTEG, and 117.3% for multi-stage PVTEG, accordingly installing multi-stage PVTEG at Israel in a typical year with an average PV yield of 1750 kWh/kW/year generates an extra 24 kWh/year per module hence avoiding fossil energy and equivalent CO2 emissions. Full article
(This article belongs to the Special Issue Miniaturized Generators, Volume II)
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15 pages, 4810 KiB  
Article
The Effects of Cogging Torque Reduction in Axial Flux Machines
by Samuel Mengesha, Shailendra Rajput, Simon Lineykin and Moshe Averbukh
Micromachines 2021, 12(3), 323; https://doi.org/10.3390/mi12030323 - 19 Mar 2021
Cited by 3 | Viewed by 3534
Abstract
An axial flux permanent magnet single-rotor generator has good potential in various applications that require high efficiency, prolonged service life, as well as low mass and dimensions. However, the effect of cogging torque diminishes generator efficiency and flexibility of functionality. The effect of [...] Read more.
An axial flux permanent magnet single-rotor generator has good potential in various applications that require high efficiency, prolonged service life, as well as low mass and dimensions. However, the effect of cogging torque diminishes generator efficiency and flexibility of functionality. The effect of cogging torque arises because of a small air gap between the stator teeth and the rotor. In this article, we suggest that shifting the opposite teeth of the stator to the optimal angle can reduce the effect of cogging torque. A special axial flux permanent magnet generator is developed to choose the optimal disposition of the permanent magnet and stator teeth in the frame. The impact of the optimal angle on the cogging torque, output power, and generator efficiency is investigated. This analytical study with experimental testing proves that the optimal angle between opposite teeth can significantly decrease cogging torque and improve output power and efficiency. The results show that cogging torque decreases significantly (4–5 times) at an optimal angle of 7.5° as compared with that of other angles, although magnetic flux and output power decline slightly but efficiency increases. Full article
(This article belongs to the Special Issue Miniaturized Generators, Volume II)
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