scholarly journals Green Route for Fabrication of Water-Treatable Thermoelectric Generators

2022 ◽  
Vol 2022 ◽  
pp. 1-12
Author(s):  
Shinichi Hata ◽  
Misaki Shiraishi ◽  
Soichiro Yasuda ◽  
Gergely Juhasz ◽  
Yukou Du ◽  
...  

Since future energy harvesting technologies require stable supply and high-efficiency energy conversion, there is an increasing demand for high-performance organic thermoelectric generators (TEGs) based on waterproof thermoelectric materials. The poor stability of n-type organic semiconductors in air and water has proved a roadblock in the development of reliable thermoelectric power generators. We developed a simple green route for preparing n-type carbon nanotubes (CNTs) by doping with cationic surfactants and fabricated films of the doped CNTs using only aqueous media. The thermoelectric properties of the CNT films were investigated in detail. The nanotubes doped using a cationic surfactant (cetyltrimethylammonium chloride (CTAC)) retained an n-doped state for at least 28 days when exposed to water and air, indicating higher stability than that for contemporary CNT-based thermoelectric materials. The wrapping of the surfactant molecules around the CNTs is responsible for blocking oxygen and water from attacking the CNT walls, thus, extending the lifetime of the n-doped state of the CNTs. We also fabricated thermoelectric power conversion modules comprising CTAC-doped (n-type) and sodium dodecylbenzenesulfonate- (SDBS-) doped (p-type) CNTs and tested their stabilities in water. The modules retained 80±2.4% of their initial maximum output power (at a temperature difference of 75°C) after being submerged in water for 30 days, even without any sealing fills to prevent device degradation. The remarkable stability of our CNT-based modules can enable the development of reliable soft electronics for underwater applications.

2014 ◽  
Vol 23 (08) ◽  
pp. 1450113 ◽  
Author(s):  
MOHAMMAD MOGHADDAM TABRIZI ◽  
NASSER MASOUMI

In this work, a novel and efficient approach is proposed to optimize linearity and efficiency of a power amplifier used in mobile communication applications. A linear and high performance push amplifier is designed and analyzed to extract design equations for an optimum performance. The proposed push amplifier has two sections; an analog section and a switching section. The analog section provides the required linearity and the switching section guarantees the satisfaction of the total efficiency level. Double power supply scheme is used in push amplifiers to enhance its performance. Two separate power supplies are employed for linear and switching sections of push amplifiers which have different voltage levels. The implemented circuit is simulated using HSPICERF with TSMC models for active and passive elements. The proposed power amplifier (PA) provides a maximum output power of 25 dBm and power added efficiency (PAE) as high as 51% at 2.5 GHz operation frequency. At 1-dB compression point, this PA exhibits output power of 25 dBm with 48% PAE and 4.5% error vector magnitude (EVM) which is appropriate for 64QAM OFDM signals.


Author(s):  
Tong Xing ◽  
Qingfeng Song ◽  
Pengfei Qiu ◽  
Qihao Zhang ◽  
Ming Gu ◽  
...  

GeTe-based materials have a great potential to be used in thermoelectric generators for waste heat recovery due to their excellent thermoelectric performance, but their module research is greatly lagging behind...


Energies ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6548
Author(s):  
Peng Liao ◽  
Jiyang Fu ◽  
Wenyong Ma ◽  
Yuan Cai ◽  
Yuncheng He

According to the engineering phenomenon of the galloping of ice-coated transmission lines at certain wind speeds, this paper proposes a novel type of energy harvester based on the galloping of a flexible structure. It uses the tension generated by the galloping structure to cause periodic strain on the piezoelectric cantilever beam, which is highly efficient for converting wind energy into electricity. On this basis, a physical model of fluid–structure interaction is established, and the Reynolds-averaged Navier–Stokes equation and SST K -ω turbulent model based on ANSYS Fluent are used to carry out a two-dimensional steady computational fluid dynamics (CFD) numerical simulation. First, the CFD technology under different grid densities and time steps is verified. CFD numerical simulation technology is used to simulate the physical model of the energy harvester, and the effect of wind speed on the lateral displacement and aerodynamic force of the flexible structure is analyzed. In addition, this paper also carries out a parameterized study on the influence of the harvester’s behavior, through the wind tunnel test, focusing on the voltage and electric power output efficiency. The harvester has a maximum output power of 119.7 μW/mm3 at the optimal resistance value of 200 KΩ at a wind speed of 10 m/s. The research results provide certain guidance for the design of a high-efficiency harvester with a square aerodynamic shape and a flexible bluff body.


2020 ◽  
Vol 16 (2) ◽  
Author(s):  
Sayed Muhammod Baker ◽  
Rinku Basak

In this work, the effects on the performance characteristics of a In0.1558Ga0.8442N / Al0.0416Ga0.9584N 3QW separate confinement heterostrcture 450 nm true blue edgeemitting laser are presented by considering different injection current. At the temperature of 300 K, the threshold current of the laser is 11 mA. The peak material gain for the designed laser is obtained as 1106 cm-1 and further used for the analysis of the performance characteristics of the designed doubleheterostructure laser for the variation of injection current. The injection current can be applied to the device is at around 12 to 15 times of the threshold current. At the value of injection current 152 mA, the maximum output power of the laser is 256.4 mW, the maximum resonance frequency is 14.5 GHz and the corresponding modulation bandwidth is 25.3 GHz at the temperature of 300 K.


2013 ◽  
Vol 1490 ◽  
pp. 185-190 ◽  
Author(s):  
Tomoyuki Nakamura ◽  
Kazuya Hatakeyama ◽  
Masahiro Minowa ◽  
Youhiko Mito ◽  
Koya Arai ◽  
...  

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.


Author(s):  
Jiaxin Song ◽  
Hanshuo Wu ◽  
Jun Ye ◽  
Hanwei Zhang ◽  
Jiangming Xu ◽  
...  

In this paper, we experimentally investigated the extreme frequency shift in high-power Raman fiber laser (RFL). The RFL was developed by using a pair of fiber Bragg gratings with fixed and matched central wavelength (1120 nm) combined with a piece of 31-m-long polarization maintaining (PM) passive fiber adopted as Raman gain medium. The pump source was a homemade high-power, linearly polarized (LP) wavelength-tunable master oscillator power amplifier (MOPA) source with ${\sim}25~\text{nm}$ tunable working range (1055–1080 nm). High-power and high-efficiency RFL with extreme frequency shift between the pump and Stokes light was explored. It is found that frequency shift located within 10.6 THz and 15.2 THz can ensure efficient Raman lasing, where the conversion efficiency is more than 95% of the maximal value, 71.3%. In addition, a maximum output power of 147.1 W was obtained with an optical efficiency of 71.3%, which is the highest power ever reported in LP RFLs to the best of our knowledge.


Author(s):  
Leon M. Headings ◽  
Shawn Midlam-Mohler ◽  
Gregory N. Washington ◽  
Joseph P. Heremans

While the thermoelectric effects have been known for over 100 years, their traditionally low conversion efficiency for power generation has limited their use to highly specialized applications. With the rapid advancement of thermoelectric materials in recent years, their inherent reliability and power density is being augmented by improvements in efficiency. Recent increases in the figure of merit of materials suitable for operation around 500 °C make them candidates for waste heat recovery, as well as primary power using combustion heaters. The characteristic scalability of thermoelectric generators makes them best suited for low power applications where alternative generators become impractical. However, with the development of thermoelectric device technology in parallel with materials advancements, it may become viable to design thermoelectric generators for auxiliary power in automotive applications. The research presented here represents the initial stages of the development of a thermoelectric power unit (TEPU). While thermoelectric generator technology can be applied to any fuel, this research targets the use of diesel fuel which is readily available for both military and consumer applications and is more easily and safely transported than many alternatives. The use of diesel fuel for a TEPU is enabled by the use of an atomizer technology developed at The Ohio State University Center for Automotive Research. A baseline prototype incorporating this novel diesel fuel atomizer/combustor with conventional thermoelectric materials and heat exchange designs has been constructed and tested. Preliminary data highlights the viability of diesel fuel for thermoelectric power generation as well as the areas which demand further development. This prototype will serve as the baseline for evaluating future designs incorporating advanced materials and novel system designs.


2020 ◽  
Author(s):  
Ke Wang ◽  
Mingyao Gao ◽  
Shuhui Yu ◽  
Jian Ning ◽  
Zhenda Xie ◽  
...  

Abstract We demonstrate a compact, high-efficiency and widely tunable intracavity singly resonant optical parametric oscillator (IC-OPO) based on multichannel periodically-poled lithium niobate (PPLN). The IC-OPO is composed of 808 nm pump laser diode (LD), Nd:YVO4 laser and linear OPO. The continuous-wave (CW) mid-infrared (MIR) output laser is tunable from 2.25 μm to 4.79 μm. The maximum output power exceeds 1.08 W at 3.189 μm at 9.1 W LD pump power and the conversion efficiency is 11.88 %. We also build up a prototype with volume of Wmm3 and its total weight is less than 2 Kg. The measured power stability is 1.3 % Root Meat Square (RMS) for a 3 h duration under simulated high temperature conditions of 40 ℃. RMS is 2.6 % for a 4 h duration when simulated temperature is - 40 ℃.


2020 ◽  
Author(s):  
Yunsheng Wang ◽  
Heqi Gao ◽  
Jie Yang ◽  
Manman Fang ◽  
Dan Ding ◽  
...  

<p><b>The study of purely organic room-temperature phosphorescence (RTP) has drawn </b><b>increasing attention </b><b>because of its considerable theoretical research and practical application </b><b>value</b><b>. Currently, organic RTP materials with both high efficiency (<i>Ф</i><sub>P</sub> > 20%) and a long lifetime (<i>τ</i><sub>P</sub> > 10 s) in air are still </b><b>scarce due to</b><b> the lack of related design guidance. Here, we </b><b>report</b><b> a new strategy to increase the phosphorescence performance of organic materials by integrating the RTP host and RTP guest in one doping system to form </b><b>a </b><b>triplet exciplex. With these materials, the high-contrast </b><b>labelling</b><b> of tumours in living mice and encrypted patterns in thermal printing are both successfully realized for the first time</b><b> by</b><b> taking </b><b>advantage of both</b><b> the long afterglow time (up to 25 min in aqueous media) and high phosphorescence efficiency (43%).</b></p>


Electronics ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 715
Author(s):  
Luwei Qi ◽  
Jin Meng ◽  
Xiaoyu Liu ◽  
Chengyue Yang ◽  
Jingtao Zhou ◽  
...  

The present work proposes a 180–225 GHz broadband frequency doubler monolithic microwave integrated circuit (MMIC) based on a novel Schottky barrier diode (SBD) terminal structure denoted as a Schottky metal-brim (SMB). Compared with an MMIC adopting the conventional SBD terminal structure, preliminary measurements show that the maximum output power of the MMIC adopting the SMB structure increases from 0.216 mW at 206 GHz to 0.914 mW at 208 GHz. Analysis of the nonlinear current–voltage and capacitance–voltage characteristics of the two terminal structures based on an extended one-dimensional drift-diffusion model, indicates that the SMB structure provides significantly better conversion efficiency than the conventional SBD structure by eliminating the accumulation of charge and additional current paths near the Schottky electrode edge. It provides a feasible scheme for the optimization of MMIC applications requiring high power and high efficiency.


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