Revisit of Thermoelectric Efficiency and Figure-of-Merit

2014 ◽  
Vol 787 ◽  
pp. 195-197
Author(s):  
Chun Lei Wang ◽  
Yuan Hu Zhu ◽  
Wen Bin Su ◽  
Jian Liu ◽  
Ji Chao Li
Keyword(s):  
Power Generation ◽  
Power Factor ◽  
Power Output ◽  
Figure Of Merit ◽  
Maximum Output Power ◽  
Load Resistance ◽  
Maximum Output ◽  
Thermoelectric Efficiency ◽  
Physical Boundary ◽  
Thermoelectric Parameters

Thermoelectric efficiency power generation represented based on the transportation equations obtained under different physical boundary conditions in the present investigation. The figure-of-merit and power factor derived from optimizing thermoelectric efficiency and maximizing power output. It is interesting to note that the maximum output power reached when the load resistance was the thermoelectric adiabatic resistance, while the optimized thermoelectric efficiency responded the isothermal resistance. The possible approach to characterizing these thermoelectric parameters proposed in the present investigation.

Modeling and experimental investigation of magnetically coupling bending-torsion piezoelectric energy harvester based on vortex-induced vibration

2021 ◽  
pp. 1045389X2110482
Author(s):  
Wentao Sui ◽  
Huirong Zhang ◽  
Chongqiu Yang ◽  
Dan Zhang ◽  
Rujun Song ◽  
...  
Keyword(s):  
Output Power ◽  
Power Output ◽  
Torsion Angle ◽  
Piezoelectric Layer ◽  
Energy Harvester ◽  
Maximum Output Power ◽  
Load Resistance ◽  
Maximum Output ◽  
Vortex Induced Vibration ◽  
Piezoelectric Energy

This paper presents a magnetically coupling bending-torsion piezoelectric energy harvester based on vortex-induced vibration from low-speed wind. The theoretical model of the energy harvester was formulated and validated by wind tunnel experiments. Numerical and experimental results showed that the power output and bandwidth of the proposed harvester are improved about 180% and 230% respectively compared with the nonmagnetic coupling harvester. Furthermore, the effects of cylinder, piezoelectric layer, load resistance, and magnetic nonlinear parameters on the harvester were investigated based on the distributed parameter model. The results showed that the length of cylinder hardly affect output power, but the diameter of cylinder presented complicated influences. The width of piezoelectric beam was negatively correlated with the torsion angle. With increasing the length of piezoelectric layer, an optimal wind velocity and load resistance can be obtained for the maximum output power. With decreasing of the distance between two magnets, the resonant bandwidth, the optimal power output, and torsion angle can be enhanced, respectively. Besides, the magnetic potential energy increased owing to the magnetically coupling, which led to the improvement of onset speed for the energy harvester. This study provides a guideline on improving the performance of bending-torsion vibration piezoelectric energy harvester.

scholarly journals Analytical Modeling of a Doubly Clamped Flexible Piezoelectric Energy Harvester with Axial Excitation and Its Experimental Characterization

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3861
Author(s):  
Jie Mei ◽  
Qiong Fan ◽  
Lijie Li ◽  
Dingfang Chen ◽  
Lin Xu ◽  
...  
Keyword(s):  
Output Power ◽  
Power Output ◽  
Output Voltage ◽  
Energy Harvester ◽  
Load Resistance ◽  
Engineering Practice ◽  
Maximum Output ◽  
Widespread Application ◽  
Piezoelectric Energy ◽  
Axial Excitation

With the rapid development of wearable electronics, novel power solutions are required to adapt to flexible surfaces for widespread applications, thus flexible energy harvesters have been extensively studied for their flexibility and stretchability. However, poor power output and insufficient sensitivity to environmental changes limit its widespread application in engineering practice. A doubly clamped flexible piezoelectric energy harvester (FPEH) with axial excitation is therefore proposed for higher power output in a low-frequency vibration environment. Combining the Euler–Bernoulli beam theory and the D’Alembert principle, the differential dynamic equation of the doubly clamped energy harvester is derived, in which the excitation mode of axial load with pre-deformation is considered. A numerical solution of voltage amplitude and average power is obtained using the Rayleigh–Ritz method. Output power of 22.5 μW at 27.1 Hz, with the optimal load resistance being 1 MΩ, is determined by the frequency sweeping analysis. In order to power electronic devices, the converted alternating electric energy should be rectified into direct current energy. By connecting to the MDA2500 standard rectified electric bridge, a rectified DC output voltage across the 1 MΩ load resistor is characterized to be 2.39 V. For further validation of the mechanical-electrical dynamical model of the doubly clamped flexible piezoelectric energy harvester, its output performances, including both its frequency response and resistance load matching performances, are experimentally characterized. From the experimental results, the maximum output power is 1.38 μW, with a load resistance of 5.7 MΩ at 27 Hz, and the rectified DC output voltage reaches 1.84 V, which shows coincidence with simulation results and is proved to be sufficient for powering LED electronics.

Power generation performance of π-structure thermoelectric device using NaCo2O4 and Mg2Si elements

2013 ◽  
Vol 1490 ◽  
pp. 185-190 ◽  
Author(s):  
Tomoyuki Nakamura ◽  
Kazuya Hatakeyama ◽  
Masahiro Minowa ◽  
Youhiko Mito ◽  
Koya Arai ◽  
...  
Keyword(s):  
Power Generation ◽  
Thermoelectric Power ◽  
Thermoelectric Properties ◽  
Waste Heat ◽  
Maximum Output Power ◽  
Magnesium Silicide ◽  
Thermoelectric Device ◽  
Maximum Output ◽  
Thermoelectric Power Generation ◽  
P Type

ABSTRACTThermoelectric power generation has been attracting attention as a technology for waste heat utilization in which thermal energy is directly converted into electric energy. It is well known that layered cobalt oxide compounds such as NaCo2O4 and Ca3Co4O9 have high thermoelectric properties in p-type oxide semiconductors. However, in most cases, the thermoelectric properties in n-type oxide materials are not as high. Therefore, n-type magnesium silicide (Mg2Si) has been studied as an alternative due to its non-toxicity, environmental friendliness, lightweight property, and comparative abundance compared with other TE systems. In this study, we fabricated π-structure thermoelectric power generation devices using p-type NaCo2O4 elements and n-type Mg2Si elements. The p- and n-type sintering bodies were fabricated by spark plasma sintering (SPS). To reduce the resistance at the interface between elements and electrodes, we processed the surface of the elements before fabricating the devices. The end face of a Mg2Si element was covered with Ni by SPS and that of a NaCo2O4 element was coated with Ag by silver paste and soldering.The thermoelectric device consisted of 18 pairs of p-type and n-type legs connected with Ag electrodes. The cross-sectional and thickness dimensions of the p-type elements were 3.0 mm × 5.0 mm × 7.6 mm (t) and those of the n-type elements were 3.0 mm × 3.0 mm × 7.6 mm (t). The open circuit voltage was 1.9 V and the maximum output power was 1.4 W at a heat source temperature of 873 K and a cooling water temperature of 283 K in air.

Investigation of Fresnel Lens Effect on Solar Panel Power Generation

2021 ◽  
Vol 80 (1) ◽  
pp. 37-49
Author(s):  
Abdul Hadi Mohaimin ◽  
Md. Rakib Uddin ◽  
Hasnul Hashim
Keyword(s):  
Power Generation ◽  
Power Output ◽  
Load Resistance ◽  
Fresnel Lens ◽  
Solar Panel ◽  
Heat Absorption ◽  
Solar Power Generation ◽  
Voltage Output ◽  
Long Run ◽  
Power Outputs

Solar panel power output can still be improved through various means. The aim of this paper is to investigate the effect on solar panel power generation due to Fresnel lens distance to the solar panel. The use of Fresnel lens is to magnify the light intensity from the sun to achieve higher solar collectability of solar panel which may increase power output. The Fresnel lens is to be positioned on top of the solar panel to concentrate the sunlight on to the solar panel. Voltages are measured by an electronic microcontroller with a 10-second interval while power output are determined by the product of voltage and load resistance connected to the solar panel. Immediate results were an instantaneous rise in voltage output but gradually decreasing with increase heat absorption in the solar panel. In the long run, voltage and power outputs were obtained at 0, 5, 10, 20, 30 and 40 cm Fresnel lens distance to the solar panel where all results saw the reduction in voltage and power generation from the solar panel incorporated with Fresnel lens compared to one without due to high ambient temperature. Because of this, it is deemed unfeasible to use Fresnel lens for solar power generation in hot areas such as those with equatorial or tropical climate.

scholarly journals Experimental Study on Piezoelectric Energy Harvesting from Vortex-Induced Vibrations and Wake-Induced Vibrations

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Min Zhang ◽  
Junlei Wang
Keyword(s):  
Energy Harvesting ◽  
Output Voltage ◽  
Maximum Output Power ◽  
Load Resistance ◽  
Maximum Output ◽  
Piezoelectric Energy ◽  
Vortex Induced Vibrations ◽  
Flow Induced Vibrations ◽  
Generation Capacity ◽  
Output Characteristics

A rigid circular cylinder with two piezoelectric beams attached on has been tested through vortex-induced vibrations (VIV) and wake-induced vibrations (WIV) by installing a big cylinder fixed upstream, in order to study the influence of the different flow-induced vibrations (FIV) types. The VIV test shows that the output voltage increases with the increases of load resistance; an optimal load resistance exists for the maximum output power. The WIV test shows that the vibration of the small cylinder is controlled by the vortex frequency of the large one. There is an optimal gap of the cylinders that can obtain the maximum output voltage and power. For a same energy harvesting device, WIV has higher power generation capacity; then the piezoelectric output characteristics can be effectively improved.

Output Power Characteristics of Mg2Si and the Fabrication of a Mg2Si TE Module with a Unileg Structure

2009 ◽  
Vol 1166 ◽  
Author(s):  
Takashi Nemoto ◽  
Tsutomu Iida ◽  
Yohei Oguni ◽  
Junichi Sato ◽  
Atsunobu Matsumoto ◽  
...  
Keyword(s):  
Power Generation ◽  
Energy Conversion ◽  
Power Output ◽  
Figure Of Merit ◽  
Thermoelectric Module ◽  
Magnesium Silicide ◽  
Hazardous Substances ◽  
Thermoelectric Device ◽  
Single Element ◽  
Dimensionless Figure Of Merit

AbstractIn order to restrain global warming and to realize a sustainable global energy system, further enhancements in energy efficiency are required. One reliable technology for reducing greenhouse gas emissions and the consumption of fossil fuel is thermoelectric technology, which can directly convert heat into electricity and consequently increases the energy conversion efficiency of power generation by combustion. Magnesium silicide (Mg2Si) is a promising candidate for a thermal-to-electric energy-conversion material at operating temperatures ranging from 500 to 800 K. Mg2Si exhibits many promising characteristics, such as the abundance of its constituent elements in the earth’s crust and the non-toxicity of its processing by-products, resulting in freedom from concerns regarding prospective extended restrictions on hazardous substances. The efficiency of a thermoelectric device is characterized by the dimensionless figure of merit, ZT. It is well known that several kinds of dopants are effective in improving the thermoelectric performance of n-type Mg2Si. With Bi-doped n-type Mg2Si, we have achieved a maximum value of the dimensionless figure-of-merit ZT of ˜1.0 at ˜ 850 K. However, the correlation between the ZT values and the power generation characteristics, which is essential to understand in order to design a structure for a TE power generation module, has not been sufficiently investigated. In order to design a structure for a thermoelectric module using Mg2Si, we examined the correlation between the ZT values and the power-output of a single element using Mg2Si (ZT = 0.6) and Mg2Si doped with donor impurities such as Al and/or Bi (ZT = 0.65˜0.77). The measured single element was 2×2 mm2 in section and 10 mm long. Additionally, we developed and evaluated a new architecture based on a ‘unileg’ structure Mg2Si TE power generation module, which can improve the module lifetime and simplify its manufacture. As a starting material for the fabrication of the single element and the TE modules, pre-synthesized polycrystalline Mg2Si, fabricated by UNION MATERIAL was used. The material was sintered using a plasma-activated sintering (PAS) technique, and, at the same time, Ni electrodes were formed on the Mg2Si by employing of a monobloc PAS technique. The thermoelectric power-outputs were measured under a temperature difference, ΔT, ranging from 100-to-500 K by using UNION MATERIAL UMTE-1000M. The observed power-output for single element of Mg2Si (ZT = 0.6), 2 at % Bi-doped Mg2Si (ZT = 0.65) and 1at % Bi + 1at % Al-doped Mg2Si (ZT = 0.77) were 23.2 mW, 13.6 mW and 19.4 mW respectively at ΔT = 500 K (between 873 K and 373 K). For the new architecture based on the unileg structure thermoelectric module, the observed value for power-output-per-unit-area was 12 mW/mm2 at ΔT = 500 K.

Design of magnetic-resonant wireless power transfer links realized with two coils: comparison of solutions

2015 ◽  
Vol 7 (3-4) ◽  
pp. 349-359 ◽  
Author(s):  
Alessandra Costanzo ◽  
Marco Dionigi ◽  
Franco Mastri ◽  
Mauro Mongiardo ◽  
Johannes A. Russer ◽  
...  
Keyword(s):  
Maximum Output Power ◽  
Wireless Power Transfer ◽  
Load Resistance ◽  
Maximum Output ◽  
Power Transfer ◽  
Wireless Power ◽  
Coupled Inductors ◽  
Link Distance ◽  
Novel Approach ◽  
General Network

A novel approach for the rigorous design of magnetic resonant wireless power transfer links is introduced. We show how, starting from two coupled inductors and making use of general network theory, it is possible to derive analytic rules for designing the source and load terminations which provide the maximum power transfer efficiency or maximize the received power. We also show that, by adding suitable matching networks to two coupled inductors we can realize a wireless link acting as a 1:n transformer and having the all required tunable reactive elements on the primary side. The proposed topology greatly simplifies the design, since only an inductive coil and a fixed capacitance are required on the secondary side; in addition, when tuning is required due to coils misalignment or to link distance variation, it can be attained by acting on the transmitter side without the need for a feedback communication through the link. Moreover, when the load resistance is designed for maximum output power, its value is fixed and does not depend on the coupling. A numerical and experimental verification of the proposed approach is also presented.

scholarly journals Cu-Ni-Based Alloys from Nanopowders as Potent Thermoelectric Materials for High-Power Output Applications

Alloys ◽  
2022 ◽  
Vol 1 (1) ◽  
pp. 3-14
Author(s):  
Mario Wolf ◽  
Jan Flormann ◽  
Timon Steinhoff ◽  
Gregory Gerstein ◽  
Florian Nürnberger ◽  
...  
Keyword(s):  
Power Factor ◽  
High Power ◽  
Thermoelectric Materials ◽  
Power Output ◽  
Figure Of Merit ◽  
Low Cost ◽  
Electrical Power ◽  
Melting Process ◽  
High Power Factor ◽  
Pure Cu

A new approach for the development of thermoelectric materials, which focuses on a high-power factor instead of a large figure of merit zT, has drawn attention in recent years. In this context, the thermoelectric properties of Cu-Ni-based alloys with a very high electrical conductivity, a moderate Seebeck coefficient, and therefore a high power factor are presented as promising low-cost alternative materials for applications aiming to have a high electrical power output. The Cu-Ni-based alloys are prepared via an arc melting process of metallic nanopowders. The heavy elements tin and tungsten are chosen for alloying to further improve the power factor while simultaneously reducing the high thermal conductivity of the resulting metal alloy, which also has a positive effect on the zT value. Overall, the samples prepared with low amounts of Sn and W show an increase in the power factor and figure of merit zT compared to the pure Cu-Ni alloy. These results demonstrate the potential of these often overlooked metal alloys and the utilization of nanopowders for thermoelectric energy conversion.

Power Generation Efficiency with Extremely Large Z factor Thermoelectric Material

2011 ◽  
Vol 1325 ◽  
Author(s):  
Kazuaki Yazawa ◽  
Ali Shakouri
Keyword(s):  
Power Generation ◽  
Thermoelectric Power ◽  
Output Power ◽  
Thermoelectric Material ◽  
Maximum Output Power ◽  
Maximum Output ◽  
Generation System ◽  
Thermoelectric Power Generation ◽  
Power Generation System ◽  
The Impact

ABSTRACTA recently developed generic model of a thermoelectric power generation system suggests a promising future for cost effective and scalable power generation. The model is based on co-optimizing the thermoelectric module together with the heat sink. Using this model, efficiency at maximum output power is calculated. It is shown that this approaches the Curzon-Ahlborn limit at very large Z values which is consistent with thermodynamic systems with irreversible heat engines. However, this happens only when the thermal resistances of the thermoelectric device with hot and cold heat sinks exactly match. For asymmetrical thermal resistances, the efficiency at maximum output power is different. This is consistent with the very recent results for the thermodynamic engines. Finally, we study the impact of lowering the thermal conductivity of the thermoelectric material or increasing its power factor and how these affect the performance of the thermoelectric power generation system.

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