Nonlinear thermoelectric transport: A class of nanodevices for high efficiency and large power output

AbstractQuantum heat engines are subjected to quantum fluctuations related to their discrete energy spectra. Such fluctuations question the reliable operation of thermal machines in the quantum regime. Here, we realize an endoreversible quantum Otto cycle in the large quasi-spin states of Cesium impurities immersed in an ultracold Rubidium bath. Endoreversible machines are internally reversible and irreversible losses only occur via thermal contact. We employ quantum control to regulate the direction of heat transfer that occurs via inelastic spin-exchange collisions. We further use full-counting statistics of individual atoms to monitor quantized heat exchange between engine and bath at the level of single quanta, and additionally evaluate average and variance of the power output. We optimize the performance as well as the stability of the quantum heat engine, achieving high efficiency, large power output and small power output fluctuations.

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EFFICIENCY OF ENERGY CONVERSION DURING SINUSOIDAL MOVEMENT OF WHITE MUSCLE FIBRES FROM THE DOGFISH SCYLIORHINUS CANICULA

Journal of Experimental Biology ◽

10.1242/jeb.183.1.137 ◽

1993 ◽

Vol 183 (1) ◽

pp. 137-147 ◽

Cited By ~ 9

Author(s):

N. A. Curtin ◽

R. C. Woledge

Keyword(s):

Power Output ◽

High Efficiency ◽

Fibre Length ◽

Dry Mass ◽

Energy Output ◽

Maximum Efficiency ◽

Muscle Fibres ◽

Work Output ◽

Sinusoidal Movement ◽

Myotomal Muscle

Net work output and heat production of white myotomal muscle fibres from the dogfish were measured during complete cycles of sinusoidal movement at 12°C. The peak-to-peak movement was about 9 % of the muscle fibre length; three stimuli at 32 ms intervals were given in each mechanical cycle. The frequency of movement and the timing of the stimulation were varied for each preparation to find the optimal conditions for power output and those optimal for efficiency (the ratio of net work output to total energy output as heat+work). To achieve either maximum power or maximum efficiency, the tetanus must start while the muscle fibres are being stretched, before the beginning of the shortening part of the mechanical cycle. The highest power output, averaged over one cycle, was 0.23+/−0.014 W g-1 dry mass (+/−s.e.m., N=9, 46.9+/−2.8 mW g-1 wet mass) and was produced during movement at 3.5 Hz. The highest efficiency, 0.41+/−0.02 (+/−s.e.m., N=13), occurred during movements at 2.0-2.5 Hz. This value is higher than the efficiency previously measured during isovelocity shortening of these fibres. The implications of the high efficiency for crossbridge models of muscle contraction are discussed.

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Heat dissipation system based on electromagnetic driven rotational flow of liquid metal coolant

Journal of Thermal Science and Engineering Applications ◽

10.1115/1.4050680 ◽

2021 ◽

pp. 1-14

Author(s):

Lei Wang ◽

Xudong Zhang ◽

Dr. Jing Liu ◽

Yixin Zhou

Keyword(s):

Liquid Metal ◽

Thermal Resistance ◽

Heat Dissipation ◽

High Efficiency ◽

Cooling System ◽

Electric Heater ◽

Power Relationship ◽

Rotational Flow ◽

Large Power ◽

Dissipation System

Abstract Liquid metal owns the highest thermal conductivity among all the currently available fluid materials. This property enables it to be a powerful coolant for the thermal management of large power device or high flux chip. In this paper, a high-efficiency heat dissipation system based on the electromagnetic driven rotational flow of liquid metal was demonstrated. The velocity distribution of the liquid metal was theoretically analyzed and numerically simulated. The results showed that the velocity was distributed unevenly along longitudinal section and the maximum velocity appears near the anode. On the temperature distribution profile of the heat dissipation system, the temperature on the electric heater side was much higher than the other regions and the role of the rotated liquid metal was to homogenize the temperature of the system. In addition, the thermal resistance model of the experimental device was established, and several relationships such as thermal resistance-power curve were experimentally measured. The heating power could be determined from the temperature-power relationship graph once the maximum control temperature was given. The heat dissipation method introduced in the paper provides a novel way for fabricating compact chip cooling system.

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Thermoelectric Transport in Sb2Te3/Bi2Te3 Quantum Dot Nanocomposites

Volume 10: Heat and Mass Transport Processes, Parts A and B ◽

10.1115/imece2011-64923 ◽

2011 ◽

Author(s):

J. Zhou ◽

R. G. Yang

Keyword(s):

Quantum Dot ◽

Transport Properties ◽

High Efficiency ◽

Phonon Scattering ◽

Transport Model ◽

Binding Model ◽

Thermoelectric Transport ◽

Bottleneck Effect ◽

Phonon Bottleneck ◽

Thermoelectric Transport Properties

We investigate the thermoelectric transport properties of Sb2Te3/Bi2Te3 quantum dot nanocomposites with spherical Sb2Te3 quantum dots arrays embedded in Bi2Te3 matrix through a two-channel transport model. In this model, the transport of quantum-confined electrons through the hopping mechanism is studied by tight-binding model together with Kubo formula and Green’s function method. The formation of minibands due to the quantum confinement and the phonon-bottleneck effect on carrier-phonon scattering are considered. The transport of bulk-like electrons is studied by Boltzmann-transport-equation-based model. We consider the intrinsic carrier scatterings as well as the carrier-interface scattering of these bulk-like electrons. Thermoelectric transport properties are studied with different quantum dot sizes, inter-dot distances, doping concentrations, and temperatures. We find that electrical conductivity and Seebeck coefficient can be enhanced simultaneously in Sb2Te3/Bi2Te3 quantum dot nanocomposites because of the formation of minibands and the phonon-bottleneck effect on carrier-phonon scattering. Our results could shed some light on the design of high-efficiency thermoelectric materials.

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Feasibility of mini combined cycles for naval applications

MATEC Web of Conferences ◽

10.1051/matecconf/201824507008 ◽

2018 ◽

Vol 245 ◽

pp. 07008 ◽

Cited By ~ 5

Author(s):

Dario Barsi ◽

Carlo Costa ◽

Francesca Satta ◽

Pietro Zunino ◽

Vitaly Sergeev

Keyword(s):

Energy Production ◽

High Efficiency ◽

Combined Cycle ◽

Pollutant Emissions ◽

Large Power ◽

Combined Use ◽

Combined Cycles ◽

Definition Of ◽

The Individual ◽

Near Future

The objective of energy production with low environmental impact will have, in the near future, high potential of development also for naval applications. The containment of pollutant emissions can be achieved by the combined use of an innovative mini gas-steam combined cycle with thermal energy cogeneration to feed the ship thermal utilities, in place of the current Diesel engine application, and liquefied natural gas as fuel (LNG). The present work is focused on the definition of the architecture of the plant, by selecting optimal distribution of pressure and temperature and repartition of power between Gas Turbine (GT), Steam Turbine (ST) and thermal utilities, as well as on the choice and sizing of the individual components. The main purpose is the definition of a compact, high efficiency, system. The proposed basic mini-cycle ranges from 2 MW to 10 MW electric power. Thanks to the combined heat and power cogeneration plant adopted, for an overall electrical efficiency of about 30%, a total return (thermal + electricity) of about 75% can be achieved. An example of plant providing large power, in a partially modular arrangement is also proposed.

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Microturbine/Fuel-Cell Coupling for High-Efficiency Electrical-Power Generation

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.1398552 ◽

2000 ◽

Vol 124 (1) ◽

pp. 110-116 ◽

Cited By ~ 50

Author(s):

A. F. Massardo ◽

C. F. McDonald ◽

T. Korakianitis

Keyword(s):

Fuel Cell ◽

Power Output ◽

Large Scale ◽

High Efficiency ◽

Waste Heat ◽

Early Stage ◽

High Reliability ◽

Unit Cost ◽

Hybrid Plant ◽

Utilization Efficiency

Microturbines and fuel cells are currently attracting a lot of attention to meet future users needs in the distributed generation market. This paper addresses a preliminary analysis of a representative state-of-the-art 50-kW microturbine coupled with a high-temperature solid-oxide fuel cell (SOFC). The technologies of the two elements of such a hybrid-power plant are in a different state of readiness. The microturbine is in an early stage of pre-production and the SOFC is still in the development phase. It is premature to propose an optimum solution. Based on today’s technology the hybrid plant, using natural gas fuel, would have a power output of about 389 kW, and an efficiency of 60 percent. If the waste heat is used the overall fuel utilization efficiency would be about 80 percent. Major features, parameters, and performance of the microturbine and the SOFC are discussed. The compatibility of the two systems is addressed, and the areas of technical concern, and mismatching issues are identified and discussed. Fully understanding these, and identifying solutions, is the key to the future establishing of an optimum overall system. This approach is viewed as being in concert with evolving technological changes. In the case of the microturbine changes will be fairly minor as they enter production on a large scale within the next year or so, but are likely to be significant for the SOFC in the next few years, as extensive efforts are expended to reduce unit cost. It is reasonable to project that a high performance and cost-effective hybrid plant, with high reliability, will be ready for commercial service in the middle of the first decade of the 21st century. While several microturbines can be packaged to give an increased level of power, this can perhaps be more effectively accomplished by coupling just a single gas turbine module with a SOFC. The resultant larger power output unit opens up new market possibilities in both the industrial nations and developing countries.

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Variability in Power Output During Cycling in International Olympic-Distance Triathlon

International Journal of Sports Physiology and Performance ◽

10.1123/ijspp.2013-0303 ◽

2014 ◽

Vol 9 (4) ◽

pp. 732-734 ◽

Cited By ~ 5

Author(s):

Naroa Etxebarria ◽

Shaun D’Auria ◽

Judith M. Anson ◽

David B. Pyne ◽

Richard A. Ferguson

Keyword(s):

Body Mass ◽

Power Output ◽

Coefficient Of Variation ◽

Aerobic Power ◽

Maximal Aerobic Power ◽

Mean Power ◽

Large Power ◽

Elite Level ◽

The Mean ◽

Mean Power Output

Purpose:The patterns of power output in the ~1-h cycle section of Olympic-distance triathlon races are not well documented. Here the authors establish a typical cycling-race profile derived from several International Triathlon Union elite-level draftinglegal triathlon races.Methods:The authors collated 12 different race power profiles from elite male triathletes (N = 5, age 25 ± 5 y, body mass 65.5 ± 5.6 kg; mean ± SD) during 7 international races. Power output was recorded using SRM cranks and analyzed with proprietary software.Results:The mean power output was 252 ± 33 W, or 3.9 ± 0.5 W/kg in relative terms, with a coefficient of variation of 71% ± 13%. Normalized power (power output an athlete could sustain if intensity were maintained constant without any variability) for the entire cycle section was 291 ± 29 W, or 40 ± 13 W higher than the actual mean power output. There were 34 ± 14 peaks of power output above 600 W and ~18% time spent at >100% of maximal aerobic power.Conclusion:Cycling during Olympic-distance triathlon, characterized by frequent and large power variations including repeat supramaximal efforts, equates to a higher workload than cycling at constant power.

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Design and Analysis of a Hybrid Solar and Vibration Energy Harvester

Energy Harvesting and Systems ◽

10.1515/ehs-2019-0006 ◽

2019 ◽

Vol 0 (0) ◽

Author(s):

M Shafiqur Rahman ◽

Uttam K. Chakravarty

Keyword(s):

Solar Radiation ◽

Cantilever Beam ◽

Power Output ◽

Energy Harvester ◽

High Efficiency ◽

Photovoltaic System ◽

Small Scale ◽

Power Calculation ◽

Hybrid Energy ◽

Harvesting Technique

AbstractThe performance of the small-scale stand-alone energy harvesters can be improved by implementing a hybrid energy harvesting technique. This paper aims at presenting the design and characterization of a hybrid energy harvester that can simultaneously harvest energy from mechanical vibration and solar radiation by combining piezoelectric, electromagnetic, electrostatic, and photovoltaic mechanisms. The hybrid device consists of a small high-efficiency solar panel and a bimorph PZT cantilever beam having a cylindrical tip magnet and two sets of capacitors (comb electrodes) attached on two sides of an ASTM 6061 T-6 Aluminum substrate. All the transducing sections of the configuration are interconnected by a smart hybrid electric circuit having a common optimum load resistance, an energy storage, and a microcontroller to generate and store combined power output when subjected to transverse vibration and solar radiation. The initial bias-voltage input required for the electrostatic mechanism is either obtained from the photovoltaic system or taken from the storage through the microcontroller. Results for the maximum power output are obtained at the fundamental resonance frequency of the vibrating cantilever beam. As the hybrid design allows a combined power harvesting method, more power is generated with better conversion efficiency than those obtained by stand-alone mechanisms. In addition to the power calculation, the study includes a stress and fatigue analysis of the cantilever beam using the finite element method to investigate the stress-life criteria of the hybrid structure.

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Observation and Characterization of the Thermoelectric Power Generation

Environment and Natural Resources Research ◽

10.5539/enrr.v8n1p94 ◽

2017 ◽

Vol 8 (1) ◽

pp. 94

Author(s):

A. J. Jin ◽

Q. Li ◽

D. Liu ◽

C. An ◽

Y. Zhang

Keyword(s):

Power Generation ◽

Thermoelectric Power ◽

Alternative Energy ◽

Response Curve ◽

High Efficiency ◽

Total Output ◽

Large Power ◽

Thermoelectric Power Generation ◽

New Findings

Authors report methodical studies on some novel, alternative energy technologies, and produced results of a thermoelectric power generation (TEPG) system. For the sake of evaluating critical thermoelectric (TE) features, they have invented the state-of-the-art equipment that has important specification capability. The studies cover the efficiency and many aspects of TEPG features as follows. A thermoelectric module is measured in situ that includes TE efficiency, force response curve, current-voltage (I-V) and power-voltage (P-V) characterization, and power temperature (P-T) response curve. They have improved both the higher total output power and the more efficient TEPG efficiency than their comparison TE devices and systems in their studies. In addition, authors will present a series of design, construction, and characterization of a thermal electric generation system which aims to achieve a large power output and high efficiency for the energy harvesting application. Furthermore, their studies lead to important knowledge of TEPG systems in terms of multi-stack modules and of the optimization in TEPG applications. Finally, the prototypes are built for both the tabletop and other applications with new findings. Several sets of prototype TEPG are developed for experimental investigation and data analysis, followed by the summary and conclusions based on the data.

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