Thermoelectric power generator with intermediate loop

DOEpatents

Bell, Lon E; Crane, Douglas Todd

2013-05-21

A thermoelectric power generator is disclosed for use to generate electrical power from heat, typically waste heat. An intermediate heat transfer loop forms a part of the system to permit added control and adjustability in the system. This allows the thermoelectric power generator to more effectively and efficiently generate power in the face of dynamically varying temperatures and heat flux conditions, such as where the heat source is the exhaust of an automobile, or any other heat source with dynamic temperature and heat flux conditions.

Thermoelectric power generator with intermediate loop

DOEpatents

Bel,; Lon, E [Altadena, CA; Crane, Douglas Todd [Pasadena, CA

2009-10-27

A thermoelectric power generator is disclosed for use to generate electrical power from heat, typically waste heat. An intermediate heat transfer loop forms a part of the system to permit added control and adjustability in the system. This allows the thermoelectric power generator to more effectively and efficiently generate power in the face of dynamically varying temperatures and heat flux conditions, such as where the heat source is the exhaust of an automobile, or any other heat source with dynamic temperature and heat flux conditions.

Modeling assisted evaluation of direct electricity generation from waste heat of wastewater via a thermoelectric generator.

PubMed

Zou, Shiqiang; Kanimba, Eurydice; Diller, Thomas E; Tian, Zhiting; He, Zhen

2018-04-22

The thermal energy represents a significant portion of energy potential in municipal wastewater and may be recovered as electricity by a thermoelectric generator (TEG). Converting heat to all-purpose electricity by TEG has been demonstrated with large heat gradients, but its application in waste heat recovery from wastewater has not been well evaluated. Herein, a bench-scale Bi 2 Te 3 -based waste heat recovery system was employed to generate electricity from a low temperature gradient through a combination of experiments and mathematical modeling. With an external resistance of 7.8 Ω and a water (hot side) flow rate of 75 mL min -1 , a maximum normalized energy recovery of 4.5 × 10 -4  kWh m -3 was achieved under a 2.8 °C temperature gradient (ΔT). Model simulation indicated a boost in both power output and energy conversion efficiency from 0.76 mW and 0.13% at ΔT = 2.8 °C to 61.83 mW and 1.15% at ΔT = 25 °C. Based on the data of two-year water/air temperature obtained from the Christiansburg Wastewater Treatment Plant, an estimated energy generation of 1094 to 70,986 kWh could be expected annually with a saving of $163 to $6076. Those results have revealed a potential for TEG-centered direct electricity generation from low-grade heat towards enhanced resource recovery from wastewater and encouraged further exploration of this approach. Copyright © 2018. Published by Elsevier B.V.

Cost Scaling of a Real-World Exhaust Waste Heat Recovery Thermoelectric Generator: A Deeper Dive

NASA Astrophysics Data System (ADS)

Hendricks, Terry J.; Yee, Shannon; LeBlanc, Saniya

2016-03-01

Cost is equally important to power density or efficiency for the adoption of waste heat recovery thermoelectric generators (TEG) in many transportation and industrial energy recovery applications. In many cases, the system design that minimizes cost (e.g., the /W value) can be very different than the design that maximizes the system's efficiency or power density, and it is important to understand the relationship between those designs to optimize TEG performance-cost compromises. Expanding on recent cost analysis work and using more detailed system modeling, an enhanced cost scaling analysis of a waste heat recovery TEG with more detailed, coupled treatment of the heat exchangers has been performed. In this analysis, the effect of the heat lost to the environment and updated relationships between the hot-side and cold-side conductances that maximize power output are considered. This coupled thermal and thermoelectric (TE) treatment of the exhaust waste heat recovery TEG yields modified cost scaling and design optimization equations, which are now strongly dependent on the heat leakage fraction, exhaust mass flow rate, and heat exchanger effectiveness. This work shows that heat exchanger costs most often dominate the overall TE system costs, that it is extremely difficult to escape this regime, and in order to achieve TE system costs of 1/W it is necessary to achieve heat exchanger costs of 1/(W/K). Minimum TE system costs per watt generally coincide with maximum power points, but preferred TE design regimes are identified where there is little cost penalty for moving into regions of higher efficiency and slightly lower power outputs. These regimes are closely tied to previously identified low cost design regimes. This work shows that the optimum fill factor F opt minimizing system costs decreases as heat losses increase, and increases as exhaust mass flow rate and heat exchanger effectiveness increase. These findings have profound implications on the design and

A Simulation Study on a Thermoelectric Generator for Waste Heat Recovery from a Marine Engine

NASA Astrophysics Data System (ADS)

Ji, Dongxu; Tseng, King Jet; Wei, Zhongbao; Zheng, Yun; Romagnoli, Alessandro

2017-05-01

In this study, a marine engine has been evaluated for waste heat recovery (WHR) using thermoelectric generators (TEG). The feasibility of Mg2Sn0.75Ge0.25, Cu2Se, and Cu1.98Se as potential thermoelectric (TE) material were investigated. A straight fin heat exchanger is used to enhance the heat transfer between the hot exhaust gas and TE modules. To facility the analysis, a system level thermal resistance model is built and validated with experiments. After the model is validated, a small marine engine with rated power of 1.7-3 MW is taken as baseline model and it is found that around 2-4 KW electrical power can be extracted from exhaust gas by the TEG at varying design and operating parameters. The back pressure effect induced by the heat exchanger is also considered in this study. Finally, a parameter study is conducted regarding the impact of the TE module height on the output power. It is shown that the height of the TE leg could play a significant role in the module geometry design, and that the optimal height varies between 1 mm and 2 mm under different heat exchangers and exhaust gas flow rates.

Automotive Thermoelectric Waste Heat Recovery

NASA Astrophysics Data System (ADS)

Meisner, Gregory P.

2015-03-01

Considerable fuel energy, as much as 70%, is not converted to useful work by internal combustion engines but is instead rejected as waste heat, and more than half of the waste heat, nearly 40% of fuel energy, is contained in vehicle exhaust gas. This provides an opportunity to recover some of the wasted fuel energy and convert it from heat into useful work, subject to the laws of thermodynamics, and thereby improve vehicle energy efficiency. Thermoelectric (TE) materials have been extensively researched and TE devices are now being developed for operation at high temperatures corresponding to automotive exhaust gases for direct solid-state conversion of heat into electricity. This has stimulated substantial progress in the development of practical TE generator (TEG) systems for large-scale commercialization. A significant enabler of this progress has been the US Department of Energy's Vehicle Technologies Program through funding for low cost solutions for automotive TE waste heat recovery to improve fuel economy. Our current project at General Motors has culminated in the identification of the potential supply chain for all components and assembly of an automotive TEG. A significant focus has been to develop integrated and iterative modeling tools for a fully optimized TEG design that includes all components and subsystems (TE modules, heat exchangers, thermal interfaces, electrical interconnects, power conditioning, and vehicle integration for maximal use of TEG power). We have built and tested a new, low-cost Initial TEG prototype based on state-of-the-art production-scale skutterudite TE modules, novel heat exchanger designs, and practical solutions to the many technical challenges for optimum TEG performance. We will use the results for our Initial TEG prototype to refine our modeling and design tools for a Final automotive TEG system prototype. Our recent results will be presented. Thanks to: J.R. Salvador, E.R. Gundlach, D. Thompson, N.K. Bucknor, M

Optimization of the Heat Exchangers of a Thermoelectric Generation System

NASA Astrophysics Data System (ADS)

Martínez, A.; Vián, J. G.; Astrain, D.; Rodríguez, A.; Berrio, I.

2010-09-01

The thermal resistances of the heat exchangers have a strong influence on the electric power produced by a thermoelectric generator. In this work, the heat exchangers of a thermoelectric generator have been optimized in order to maximize the electric power generated. This thermoelectric generator harnesses heat from the exhaust gas of a domestic gas boiler. Statistical design of experiments was used to assess the influence of five factors on both the electric power generated and the pressure drop in the chimney: height of the generator, number of modules per meter of generator height, length of the fins of the hot-side heat exchanger (HSHE), length of the gap between fins of the HSHE, and base thickness of the HSHE. The electric power has been calculated using a computational model, whereas Fluent computational fluid dynamics (CFD) has been used to obtain the thermal resistances of the heat exchangers and the pressure drop. Finally, the thermoelectric generator has been optimized, taking into account the restrictions on the pressure drop.

Microturbine and Thermoelectric Generator Combined System: A Case Study.

PubMed

Miozzo, Alvise; Boldrini, Stefano; Ferrario, Alberto; Fabrizio, Monica

2017-03-01

Waste heat recovery is one of the suitable industrial applications of thermoelectrics. Thermoelectric generators (TEG) are used, commonly, only for low-mid size power generation systems. The low efficiency of thermoelectric modules generally does not encourage their combination with high power and temperature sources, such as gas turbines. Nevertheless, the particular features of thermoelectric technology (no moving parts, scalability, reliability, low maintenance costs) are attractive for many applications. In this work, the feasibility of the integration of a TE generator into a cogeneration system is evaluated. The cogeneration system consists of a microturbine and heat exchangers for the production of electrical and thermal energy. The aim is to improve electric power generation by using TE modules and the “free” thermal energy supplied by the cogeneration system, through the exhaust pipe of the microturbine. Three different solutions for waste heat recovery from the exhausts gas are evaluated, from the fluid dynamics and heat transfer point of view, to find out a suitable design strategy for a combined power generation system.

Passive flow heat exchanger simulation for power generation from solar pond using thermoelectric generators

NASA Astrophysics Data System (ADS)

Baharin, Nuraida'Aadilia; Arzami, Amir Afiq; Singh, Baljit; Remeli, Muhammad Fairuz; Tan, Lippong; Oberoi, Amandeep

2017-04-01

In this study, a thermoelectric generator heat exchanger system was designed and simulated for electricity generation from solar pond. A thermoelectric generator heat exchanger was studied by using Computational Fluid Dynamics to simulate flow and heat transfer. A thermoelectric generator heat exchanger designed for passive in-pond flow used in solar pond for electrical power generation. A simple analysis simulation was developed to obtain the amount of electricity generated at different conditions for hot temperatures of a solar pond at different flow rates. Results indicated that the system is capable of producing electricity. This study and design provides an alternative way to generate electricity from solar pond in tropical countries like Malaysia for possible renewable energy applications.

Thermoelectric generators incorporating phase-change materials for waste heat recovery from engine exhaust

DOEpatents

Meisner, Gregory P; Yang, Jihui

2014-02-11

Thermoelectric devices, intended for placement in the exhaust of a hydrocarbon fuelled combustion device and particularly suited for use in the exhaust gas stream of an internal combustion engine propelling a vehicle, are described. Exhaust gas passing through the device is in thermal communication with one side of a thermoelectric module while the other side of the thermoelectric module is in thermal communication with a lower temperature environment. The heat extracted from the exhaust gasses is converted to electrical energy by the thermoelectric module. The performance of the generator is enhanced by thermally coupling the hot and cold junctions of the thermoelectric modules to phase-change materials which transform at a temperature compatible with the preferred operating temperatures of the thermoelectric modules. In a second embodiment, a plurality of thermoelectric modules, each with a preferred operating temperature and each with a uniquely-matched phase-change material may be used to compensate for the progressive lowering of the exhaust gas temperature as it traverses the length of the exhaust pipe.

Fabrication of Thermoelectric Devices Using Additive-Subtractive Manufacturing Techniques: Application to Waste-Heat Energy Harvesting

NASA Astrophysics Data System (ADS)

Tewolde, Mahder

Thermoelectric generators (TEGs) are solid-state devices that convert heat directly into electricity. They are well suited for waste-heat energy harvesting applications as opposed to primary energy generation. Commercially available thermoelectric modules are flat, inflexible and have limited sizes available. State-of-art manufacturing of TEG devices relies on assembling prefabricated parts with soldering, epoxy bonding, and mechanical clamping. Furthermore, efforts to incorporate them onto curved surfaces such as exhaust pipes, pump housings, steam lines, mixing containers, reaction chambers, etc. require custom-built heat exchangers. This is costly and labor-intensive, in addition to presenting challenges in terms of space, thermal coupling, added weight and long-term reliability. Additive manufacturing technologies are beginning to address many of these issues by reducing part count in complex designs and the elimination of sub-assembly requirements. This work investigates the feasibility of utilizing such novel manufacturing routes for improving the manufacturing process of thermoelectric devices. Much of the research in thermoelectricity is primarily focused on improving thermoelectric material properties by developing of novel materials or finding ways to improve existing ones. Secondary to material development is improving the manufacturing process of TEGs to provide significant cost benefits. To improve the device fabrication process, this work explores additive manufacturing technologies to provide an integrated and scalable approach for TE device manufacturing directly onto engineering component surfaces. Additive manufacturing techniques like thermal spray and ink-dispenser printing are developed with the aim of improving the manufacturing process of TEGs. Subtractive manufacturing techniques like laser micromachining are also studied in detail. This includes the laser processing parameters for cutting the thermal spray materials efficiently by

Independent Power Generation in a Modern Electrical Substation Based on Thermoelectric Technology

NASA Astrophysics Data System (ADS)

Li, Z. M.; Zhao, Y. Q.; Liu, W.; Wei, B.; Qiu, M.; Lai, X. K.

2017-05-01

Because of many types of electrical equipment with high power in substations, the potentiality of energy conservation is quite large. From this viewpoint, thermoelectric materials may be chosen to produce electrical energy using the waste heat produced in substations. Hence, a thermoelectric generation system which can recycle the waste heat from electric transformers was proposed to improve the energy efficiency and reduce the burden of the oil cooling system. An experimental prototype was fabricated to perform the experiment and to verify the feasibility. The experimental results showed that the output power could achieve 16 W from waste heat of 900 W, and that the power conversion efficiency was approximately 1.8%. Therefore, power generation is feasible by using the waste heat from the transformers based on thermoelectric technology.

Development of a Small Thermoelectric Generators Prototype for Energy Harvesting from Low Temperature Waste Heat at Industrial Plant.

PubMed

Chiarotti, Ugo; Moroli, Valerio; Menchetti, Fernando; Piancaldini, Roberto; Bianco, Loris; Viotto, Alberto; Baracchini, Giulia; Gaspardo, Daniele; Nazzi, Fabio; Curti, Maurizio; Gabriele, Massimiliano

2017-03-01

A 39-W thermoelectric generator prototype has been realized and then installed in industrial plant for on-line trials. The prototype was developed as an energy harvesting demonstrator using low temperature cooling water waste heat as energy source. The objective of the research program is to measure the actual performances of this kind of device working with industrial water below 90 °C, as hot source, and fresh water at a temperature of about 15 °C, as cold sink. The article shows the first results of the research program. It was verified, under the tested operative conditions, that the produced electric power exceeds the energy required to pump the water from the hot source and cold sink to the thermoelectric generator unit if they are located at a distance not exceeding 50 m and the electric energy conversion efficiency is 0.33%. It was calculated that increasing the distance of the hot source and cold sink to the thermoelectric generator unit to 100 m the produced electric energy equals the energy required for water pumping, while reducing the distance of the hot source and cold sink to zero meters the developed unit produces an electric energy conversion efficiency of 0.61%.

Validation of a Waste Heat Recovery Model for a 1kW PEM Fuel Cell using Thermoelectric Generator

NASA Astrophysics Data System (ADS)

Saufi Sulaiman, M.; Mohamed, W. A. N. W.; Singh, B.; Fitrie Ghazali, M.

2017-08-01

Fuel cell is a device that generates electricity through electrochemical reaction between hydrogen and oxygen. A major by-product of the exothermic reaction is waste heat. The recovery of this waste heat has been subject to research on order to improve the overall energy utilization. However, nearly all of the studies concentrate on high temperature fuel cells using advanced thermodynamic cycles due to the high quality of waste heat. The method, characteristics and challenges in harvesting waste heat from a low temperature fuel cell using a direct energy conversion device is explored in this publication. A heat recovery system for an open cathode 1kW Proton Exchange Membrane fuel cell (PEM FC) was developed using a single unit of thermoelectric generator (TEG) attached to a heat pipe. Power output of the fuel cell was varied to obtain the performance of TEG at different stack temperatures. Natural and forced convections modes of cooling were applied to the TEG cold side. This is to simulate the conditions of a mini fuel cell vehicle at rest and in motion. The experimental results were analysed and a mathematical model based on the thermal circuit analogy was developed and compared. Forced convection mode resulted in higher temperature difference, output voltage and maximum power which are 3.3°C, 33.5 mV, and 113.96mW respectively. The heat recovery system for 1 kW Proton Exchange Membrane fuel cell (PEM FC) using single TEG was successfully established and improved the electrical production of fuel cell. Moreover, the experimental results obtained was in a good agreement with theoretical results.

Finite element analysis on the thermoelectric generator for the waste heat recovery of solar application

NASA Astrophysics Data System (ADS)

Zulkifli, Muhammad Nubli; Ilias, Izzudin; Abas, Amir; Muhamad, Wan Mansor Wan

2017-09-01

Thermoelectric generator (TEG) is the solid state device that converts the thermal gradient into electrical energy. TEG is widely used as the renewable energy source especially for the electronic equipment that operates with the small amount of electrical power. In the present analysis, the finite element analysis (FEA) using ANSYS is conducted on a model of the TEG attached with the aluminium, Al plate on the hot side of the TEG. This simple construction of TEG model was built in order to be used in the waste heat recovery of solar application. It was shown that the changes of the area and thickness of the Al plate increased the temperature gradient between hot and cold sides of TEG. This directly increase the voltage produced by the TEG based on the Seeback effect. The increase of the thermal gradient due to the increment of thickness and width of Al plate might be because of the increase of thermal resistance of Al plate. This finding provides a valuable data in design process to build a good TEG attached with Al plate for the waste heat recovery of solar application.

Direct waste heat recovery via thermoelectric materials - chosen issues of the thermodynamic description

NASA Astrophysics Data System (ADS)

Kolasiński, Piotr; Kolasińska, Ewa

2016-02-01

The effective waste heat recovery is one of the present-day challenges in the industry and power engineering. The energy systems dedicated for waste heat conversion into electricity are usually characterized by low efficiency and are complicated in the design. The possibility of waste heat recovery via thermoelectric materials may be an interesting alternative to the currently used technologies. In particular, due to their material characteristics, conducting polymers may be competitive when compared with the power machinery and equipment. These materials can be used in a wide range of the geometries e.g. the bulk products, thin films, pristine form or composites and the others. In this article, the authors present selected issues related to the mathematical and thermodynamic description of the heat transfer processes in the thermoelectric materials dedicated for the waste heat recovery. The link of these models with electrical properties of the material and a material solution based on a conducting polymer have also been presented in this paper.

Superconducting thermoelectric generator

DOEpatents

Metzger, J.D.; El-Genk, M.S.

1994-01-01

Thermoelectricity is produced by applying a temperature differential to dissimilar electrically conducting or semiconducting materials, thereby producing a voltage that is proportional to the temperature difference. Thermoelectric generators use this effect to directly convert heat into electricity; however, presently-known generators have low efficiencies due to the production of high currents which in turn cause large resistive heating losses. Some thermoelectric generators operate at efficiencies between 4% and 7% in the 800{degrees} to 1200{degrees}C range. According to its major aspects and bradly stated, the present invention is an apparatus and method for producing electricity from heat. In particular, the invention is a thermoelectric generator that juxtaposes a superconducting material and a semiconducting material - so that the superconducting and the semiconducting materials touch - to convert heat energy into electrical energy without resistive losses in the temperature range below the critical temperature of the superconducting material. Preferably, an array of superconducting material is encased in one of several possible configurations within a second material having a high thermal conductivity, preferably a semiconductor, to form a thermoelectric generator.

Weight Penalty Incurred in Thermoelectric Recovery of Automobile Exhaust Heat

NASA Astrophysics Data System (ADS)

Rowe, D. M.; Smith, J.; Thomas, G.; Min, G.

2011-05-01

Thermoelectric recovery of automobile waste exhaust heat has been identified as having potential for reducing fuel consumption and environmentally unfriendly emissions. Around 35% of combustion energy is discharged as heat through the exhaust system, at temperatures which depend upon the engine's operation and range from 800°C to 900°C at the outlet port to less than 50°C at the tail-pipe. Beneficial reduction in fuel consumption of 5% to 10% is widely quoted in the literature. However, comparison between claims is difficult due to nonuniformity of driving conditions. In this paper the available waste exhaust heat energy produced by a 1.5 L family car when undergoing the new European drive cycle was measured and the potential thermoelectric output estimated. The work required to power the vehicle through the drive cycle was also determined and used to evaluate key parameters. This enabled an estimate to be made of the engine efficiency and additional work required by the engine to meet the load of a thermoelectric generating system. It is concluded that incorporating a thermoelectric generator would attract a penalty of around 12 W/kg. Employing thermoelectric modules fabricated from low-density material such as magnesium silicide would considerably reduce the generator weight penalty.

Solar thermoelectric generator

DOEpatents

Toberer, Eric S.; Baranowski, Lauryn L.; Warren, Emily L.

2016-05-03

Solar thermoelectric generators (STEGs) are solid state heat engines that generate electricity from concentrated sunlight. A novel detailed balance model for STEGs is provided and applied to both state-of-the-art and idealized materials. STEGs can produce electricity by using sunlight to heat one side of a thermoelectric generator. While concentrated sunlight can be used to achieve extremely high temperatures (and thus improved generator efficiency), the solar absorber also emits a significant amount of black body radiation. This emitted light is the dominant loss mechanism in these generators. In this invention, we propose a solution to this problem that eliminates virtually all of the emitted black body radiation. This enables solar thermoelectric generators to operate at higher efficiency and achieve said efficient with lower levels of optical concentration. The solution is suitable for both single and dual axis solar thermoelectric generators.

A 3D TCAD simulation of a thermoelectric module configured for thermoelectric power generation, cooling and heating

NASA Astrophysics Data System (ADS)

Gould, C. A.; Shammas, N. Y. A.; Grainger, S.; Taylor, I.; Simpson, K.

2012-06-01

This paper documents the 3D modeling and simulation of a three couple thermoelectric module using the Synopsys Technology Computer Aided Design (TCAD) semiconductor simulation software. Simulation results are presented for thermoelectric power generation, cooling and heating, and successfully demonstrate the basic thermoelectric principles. The 3D TCAD simulation model of a three couple thermoelectric module can be used in the future to evaluate different thermoelectric materials, device structures, and improve the efficiency and performance of thermoelectric modules.

Experimental study of a sustainable hybrid system for thermoelectric generation and freshwater production

NASA Astrophysics Data System (ADS)

de Souza, Gabriel Fernandes; Tan, Lippong; Singh, Baljit; Ding, Lai Chet; Date, Abhijit

2017-04-01

The paper presents a sustainable hybrid system, which is capable of generating electricity and producing freshwater from seawater using low grade heat source. This proposed system uses low grade heat that can be supplied from solar radiation, industrial waste heat or any other waste heat sources where the temperature is less than 150°C. The concept behind this system uses the Seebeck effect for thermoelectricity generation via incorporating the low boiling point of seawater under sub-atmospheric ambient pressure. A lab-test prototype of the proposed system was built and experimentally tested in RMIT University. The prototype utilised four commercial available thermoelectric generators (Bi2Te3) and a vacuum vessel to achieve the simultaneous production of electricity and freshwater. The temperature profiles, thermoelectric powers and freshwater productions were determined at several levels of salinity to study the influence of different salt concentrations. The theoretical description of system design and experimental results were analysed and discussed in detailed. The experiment results showed that 0.75W of thermoelectricity and 404g of freshwater were produced using inputs of 150W of simulated waste heat and 500g of 3% saline water. The proposed hybrid concept has demonstrated the potential to become the future sustainable system for electricity and freshwater productions.

Performance evaluation of an automotive thermoelectric generator

NASA Astrophysics Data System (ADS)

Dubitsky, Andrei O.

Around 40% of the total fuel energy in typical internal combustion engines (ICEs) is rejected to the environment in the form of exhaust gas waste heat. Efficient recovery of this waste heat in automobiles can promise a fuel economy improvement of 5%. The thermal energy can be harvested through thermoelectric generators (TEGs) utilizing the Seebeck effect. In the present work, a versatile test bench has been designed and built in order to simulate conditions found on test vehicles. This allows experimental performance evaluation and model validation of automotive thermoelectric generators. An electrically heated exhaust gas circuit and a circulator based coolant loop enable integrated system testing of hot and cold side heat exchangers, thermoelectric modules (TEMs), and thermal interface materials at various scales. A transient thermal model of the coolant loop was created in order to design a system which can maintain constant coolant temperature under variable heat input. Additionally, as electrical heaters cannot match the transient response of an ICE, modelling was completed in order to design a relaxed exhaust flow and temperature history utilizing the system thermal lag. This profile reduced required heating power and gas flow rates by over 50%. The test bench was used to evaluate a DOE/GM initial prototype automotive TEG and validate analytical performance models. The maximum electrical power generation was found to be 54 W with a thermal conversion efficiency of 1.8%. It has been found that thermal interface management is critical for achieving maximum system performance, with novel designs being considered for further improvement.

Detailed Modeling and Irreversible Transfer Process Analysis of a Multi-Element Thermoelectric Generator System

NASA Astrophysics Data System (ADS)

Xiao, Heng; Gou, Xiaolong; Yang, Suwen

2011-05-01

Thermoelectric (TE) power generation technology, due to its several advantages, is becoming a noteworthy research direction. Many researchers conduct their performance analysis and optimization of TE devices and related applications based on the generalized thermoelectric energy balance equations. These generalized TE equations involve the internal irreversibility of Joule heating inside the thermoelectric device and heat leakage through the thermoelectric couple leg. However, it is assumed that the thermoelectric generator (TEG) is thermally isolated from the surroundings except for the heat flows at the cold and hot junctions. Since the thermoelectric generator is a multi-element device in practice, being composed of many fundamental TE couple legs, the effect of heat transfer between the TE couple leg and the ambient environment is not negligible. In this paper, based on basic theories of thermoelectric power generation and thermal science, detailed modeling of a thermoelectric generator taking account of the phenomenon of energy loss from the TE couple leg is reported. The revised generalized thermoelectric energy balance equations considering the effect of heat transfer between the TE couple leg and the ambient environment have been derived. Furthermore, characteristics of a multi-element thermoelectric generator with irreversibility have been investigated on the basis of the new derived TE equations. In the present investigation, second-law-based thermodynamic analysis (exergy analysis) has been applied to the irreversible heat transfer process in particular. It is found that the existence of the irreversible heat convection process causes a large loss of heat exergy in the TEG system, and using thermoelectric generators for low-grade waste heat recovery has promising potential. The results of irreversibility analysis, especially irreversible effects on generator system performance, based on the system model established in detail have guiding significance for

Thermoelectric power generator for variable thermal power source

DOEpatents

Bell, Lon E; Crane, Douglas Todd

2015-04-14

Traditional power generation systems using thermoelectric power generators are designed to operate most efficiently for a single operating condition. The present invention provides a power generation system in which the characteristics of the thermoelectrics, the flow of the thermal power, and the operational characteristics of the power generator are monitored and controlled such that higher operation efficiencies and/or higher output powers can be maintained with variably thermal power input. Such a system is particularly beneficial in variable thermal power source systems, such as recovering power from the waste heat generated in the exhaust of combustion engines.

Thermoelectric Waste Heat Recovery Program for Passenger Vehicles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jovovic, Vladimir

2015-12-31

Gentherm began work in October 2011 to develop a Thermoelectric Waste Energy Recovery System for passenger vehicle applications. Partners in this program were BMW and Tenneco. Tenneco, in the role of TIER 1 supplier, developed the system-level packaging of the thermoelectric power generator. As the OEM, BMW Group demonstrated the TEG system in their vehicle in the final program phase. Gentherm demonstrated the performance of the TEG in medium duty and heavy duty vehicles. Technology developed and demonstrated in this program showed potential to reduce fuel consumption in medium and heavy duty vehicles. In light duty vehicles it showed moremore » modest potential.« less

Thermoelectric energy converter for generation of electricity from low-grade heat

DOEpatents

Jayadev, T.S.; Benson, D.K.

1980-05-27

A thermoelectric energy conversion device which includes a plurality of thermoelectric elements is described. A hot liquid is supplied to one side of each element and a cold liquid is supplied to the other side of each element. The thermoelectric generator may be utilized to produce power from low-grade heat sources such as ocean thermal gradients, solar ponds, and low-grade geothermal resources. (WHK)

From Modules to a Generator: An Integrated Heat Exchanger Concept for Car Applications of a Thermoelectric Generator

NASA Astrophysics Data System (ADS)

Bosch, Henry

2016-03-01

A heat exchanger concept for a thermoelectric generator with integrated planar modules for passenger car applications is introduced. The module housings, made of deep drawn stainless steel sheet metal, are brazed onto the exhaust gas channel to achieve an optimal heat transfer on the hot side of the modules. The cooling side consists of winding fluid channels, which are mounted directly onto the cold side of the modules. Only a thin foil separates the cooling media from the modules for an almost direct heat contact on the cooling side. Thermoelectric generators with up to 20 modules made of PbTe and Bi2Te3, respectively, are manufactured and tested on a hot gas generator to investigate electrical power output and performance of the thermoelectric generator. The proof of concept of the light weight heat exchanger design made of sheet metal with integrated modules is positively accomplished.

Thermoelectric Power Generation System for Future Hybrid Vehicles Using Hot Exhaust Gas

NASA Astrophysics Data System (ADS)

Kim, Sun-Kook; Won, Byeong-Cheol; Rhi, Seok-Ho; Kim, Shi-Ho; Yoo, Jeong-Ho; Jang, Ju-Chan

2011-05-01

The present experimental and computational study investigates a new exhaust gas waste heat recovery system for hybrid vehicles, using a thermoelectric module (TEM) and heat pipes to produce electric power. It proposes a new thermoelectric generation (TEG) system, working with heat pipes to produce electricity from a limited hot surface area. The current TEG system is directly connected to the exhaust pipe, and the amount of electricity generated by the TEMs is directly proportional to their heated area. Current exhaust pipes fail to offer a sufficiently large hot surface area for the high-efficiency waste heat recovery required. To overcome this, a new TEG system has been designed to have an enlarged hot surface area by the addition of ten heat pipes, which act as highly efficient heat transfer devices and can transmit the heat to many TEMs. As designed, this new waste heat recovery system produces a maximum 350 W when the hot exhaust gas heats the evaporator surface of the heat pipe to 170°C; this promises great possibilities for application of this technology in future energy-efficient hybrid vehicles.

Microfabricated thermoelectric power-generation devices

NASA Technical Reports Server (NTRS)

Fleurial, Jean-Pierre (Inventor); Ryan, Margaret A. (Inventor); Borshchevsky, Alex (Inventor); Phillips, Wayne (Inventor); Kolawa, Elizabeth A. (Inventor); Snyder, G. Jeffrey (Inventor); Caillat, Thierry (Inventor); Kascich, Thorsten (Inventor); Mueller, Peter (Inventor)

2004-01-01

A device for generating power to run an electronic component. The device includes a heat-conducting substrate (composed, e.g., of diamond or another high thermal conductivity material) disposed in thermal contact with a high temperature region. During operation, heat flows from the high temperature region into the heat-conducting substrate, from which the heat flows into the electrical power generator. A thermoelectric material (e.g., a BiTe alloy-based film or other thermoelectric material) is placed in thermal contact with the heat-conducting substrate. A low temperature region is located on the side of the thermoelectric material opposite that of the high temperature region. The thermal gradient generates electrical power and drives an electrical component.

Microfabricated thermoelectric power-generation devices

NASA Technical Reports Server (NTRS)

Fleurial, Jean-Pierre (Inventor); Phillips, Wayne (Inventor); Borshchevsky, Alex (Inventor); Kolawa, Elizabeth A. (Inventor); Ryan, Margaret A. (Inventor); Caillat, Thierry (Inventor); Mueller, Peter (Inventor); Snyder, G. Jeffrey (Inventor); Kascich, Thorsten (Inventor)

2002-01-01

A device for generating power to run an electronic component. The device includes a heat-conducting substrate (composed, e.g., of diamond or another high thermal conductivity material) disposed in thermal contact with a high temperature region. During operation, heat flows from the high temperature region into the heat-conducting substrate, from which the heat flows into the electrical power generator. A thermoelectric material (e.g., a BiTe alloy-based film or other thermoelectric material) is placed in thermal contact with the heat-conducting substrate. A low temperature region is located on the side of the thermoelectric material opposite that of the high temperature region. The thermal gradient generates electrical power and drives an electrical component.

Optimal Design of an Automotive Exhaust Thermoelectric Generator

NASA Astrophysics Data System (ADS)

Fagehi, Hassan; Attar, Alaa; Lee, Hosung

2018-07-01

The consumption of energy continues to increase at an exponential rate, especially in terms of conventional automobiles. Approximately 40% of the applied fuel into a vehicle is lost as waste exhausted to the environment. The desire for improved fuel efficiency by recovering the exhaust waste heat in automobiles has become an important subject. A thermoelectric generator (TEG) has the potential to convert exhaust waste heat into electricity as long as it is improving fuel economy. The remarkable amount of research being conducted on TEGs indicates that this technology will have a bright future in terms of power generation. The current study discusses the optimal design of the automotive exhaust TEG. An experimental study has been conducted to verify the model that used the ideal (standard) equations along with effective material properties. The model is reasonably verified by experimental work, mainly due to the utilization of the effective material properties. Hence, the thermoelectric module that was used in the experiment was optimized by using a developed optimal design theory (dimensionless analysis technique).

Optimal Design of an Automotive Exhaust Thermoelectric Generator

NASA Astrophysics Data System (ADS)

Fagehi, Hassan; Attar, Alaa; Lee, Hosung

2018-04-01

The consumption of energy continues to increase at an exponential rate, especially in terms of conventional automobiles. Approximately 40% of the applied fuel into a vehicle is lost as waste exhausted to the environment. The desire for improved fuel efficiency by recovering the exhaust waste heat in automobiles has become an important subject. A thermoelectric generator (TEG) has the potential to convert exhaust waste heat into electricity as long as it is improving fuel economy. The remarkable amount of research being conducted on TEGs indicates that this technology will have a bright future in terms of power generation. The current study discusses the optimal design of the automotive exhaust TEG. An experimental study has been conducted to verify the model that used the ideal (standard) equations along with effective material properties. The model is reasonably verified by experimental work, mainly due to the utilization of the effective material properties. Hence, the thermoelectric module that was used in the experiment was optimized by using a developed optimal design theory (dimensionless analysis technique).

Thermoelectric Generation Of Current - Theoretical And Experimental Analysis

NASA Astrophysics Data System (ADS)

Ruciński, Adam; Rusowicz, Artur

2017-12-01

This paper provides some information about thermoelectric technology. Some new materials with improved figures of merit are presented. These materials in Peltier modules make it possible to generate electric current thanks to a temperature difference. The paper indicates possible applications of thermoelectric modules as interesting tools for using various waste heat sources. Some zero-dimensional equations describing the conditions of electric power generation are given. Also, operating parameters of Peltier modules, such as voltage and electric current, are analyzed. The paper shows chosen characteristics of power generation parameters. Then, an experimental stand for ongoing research and experimental measurements are described. The authors consider the resistance of a receiver placed in the electric circuit with thermoelectric elements. Finally, both the analysis of experimental results and conclusions drawn from theoretical findings are presented. Voltage generation of about 1.5 to 2.5 V for the temperature difference from 65 to 85 K was observed when a bismuth telluride thermoelectric couple (traditionally used in cooling technology) was used.

Optimization of Thermoelectric Components for Automobile Waste Heat Recovery Systems

NASA Astrophysics Data System (ADS)

Kumar, Sumeet; Heister, Stephen D.; Xu, Xianfan; Salvador, James R.

2015-10-01

For a typical spark ignition engine approximately 40% of available thermal energy is lost as hot exhaust gas. To improve fuel economy, researchers are currently evaluating technology which exploits exhaust stream thermal power by use of thermoelectric generators (TEGs) that operate on the basis of the Seebeck effect. A 5% improvement in fuel economy, achieved by use of TEG output power, is a stated objective for light-duty trucks and personal automobiles. System modeling of thermoelectric (TE) components requires solution of coupled thermal and electric fluxes through the n and p-type semiconductor legs, given appropriate thermal boundary conditions at the junctions. Such applications have large thermal gradients along the semiconductor legs, and material properties are highly dependent on spatially varying temperature profiles. In this work, one-dimensional heat flux and temperature variations across thermoelectric legs were solved by using an iterative numerical approach to optimize both TE module and TEG designs. Design traits were investigated by assuming use of skutterudite as a thermoelectric material with potential for automotive applications in which exhaust gas and heat exchanger temperatures typically vary from 100°C to over 600°C. Dependence of leg efficiency, thermal fluxes and electric power generation on leg geometry, fill fractions, electric current, thermal boundary conditions, etc., were studied in detail. Optimum leg geometries were computed for a variety of automotive exhaust conditions.

Performance study of thermo-electric generator

NASA Astrophysics Data System (ADS)

Rohit, G.; Manaswini, D.; Kotebavi, Vinod; R, Nagaraja S.

2017-07-01

Devices like automobiles, stoves, ovens, boilers, kilns and heaters dissipate large amount of waste heat. Since most of this waste heat goes unused, the efficiency of these devices is drastically reduced. A lot of research is being conducted on the recovery of the waste heat, among which Thermoelectric Generators (TEG) is one of the popular method. TEG is a semiconductor device that produces electric potential difference when a thermal gradient develops on it. This paper deals with the study of performance of a TEG module for different hot surface temperatures. Performance characteristics used here are voltage, current and power developed by the TEG. One side of the TEG was kept on a hot plate where uniform heat flux was supplied to that. And the other side was cooled by supplying cold water. The results show that the output power increases significantly with increase in the temperature of the hot surface.

CFD modeling of thermoelectric generators in automotive EGR-coolers

NASA Astrophysics Data System (ADS)

Högblom, Olle; Andersson, Ronnie

2012-06-01

A large amount of the waste heat in the exhaust gases from diesel engines is removed in the exhaust gas recirculation (EGR) cooler. Introducing a thermoelectric generator (TEG) in an EGR cooler requires a completely new design of the heat exchanger. To accomplish that a model of the TEG-EGR system is required. In this work, a transient 3D CFD model for simulation of gas flow, heat transfer and power generation has been developed. This model allows critical design parameters in the TEG-EGR to be identified and design requirements for the systems to be specified. Besides the prediction of Seebeck, Peltier, Thomson and Joule effects, the simulations also give detailed insight to the temperature gradients in the gas-phase and inside the thermoelectric (TE) elements. The model is a very valuable tool to identify bottlenecks, improve design, select optimal TE materials and operating conditions. The results show that the greatest heat transfer resistance is located in the gas phase and it is critical to reduce this in order to achieve a large temperature difference over the thermoelectric elements without compromising on the maximum allowable pressure drop in the system. Further results from an investigation of the thermoelectric performance during a vehicle test cycle is presented.

An experimental investigation of a thermoelectric power generation system with different cold-side heat dissipation

NASA Astrophysics Data System (ADS)

Li, Y. H.; Wu, Z. H.; Xie, H. Q.; Xing, J. J.; Mao, J. H.; Wang, Y. Y.; Li, Z.

2018-01-01

Thermoelectric generation technology has attracted increasing attention because of its promising applications. In this work, the heat transfer characteristics and the performance of a thermoelectric generator (TEG) with different cold-side heat dissipation intensity has been studied. By fixing the hot-side temperature of TEG, the effects of various external conditions including the flow rate and the inlet temperature of the cooling water flowing through the cold-sided heat sink have been investigated detailedly. It was showed that the output power and the efficiency of TEG increased with temperature different enlarged, whereas the efficiency of TEG reduced with flow rate increased. It is proposed that more heat taken by the cooling water is attributed to the efficiency decrease when the flow rate of the cooling water is increased. This study would provide fundamental understanding for the design of more refined thermoelectric generation systems.

Modeling and Simulations on the Intramural Thermoelectric Generator of Lower-Re-fluid

NASA Astrophysics Data System (ADS)

Zhang, Zheng; Zheng, Ding; Chen, Yushan

The thermoelectric conversion with lower Renault number (Re) fluid, such as waste heat from industry boiler, and engine's circled cooling water, which can be designed as intramural generator structure. In this research, a thermoelectric project analysis model and the description of an intensified system are presented, its generator with the aligned or staggered platoon structure has strengthened heat-transfer property, and the heat convection coefficient ratio has increased times than plain tube; For the fluid kinetic energy's loss is influenced by the whirlpool, the pressure difference is several hundred Pa level which changes along with geometric parameters of transform components; what's more, heat transfer area increase distinctly under the same generator volume, which has built the foundation for the enhancement output electric power.

Performance of a Half-Heusler Thermoelectric Generator for Automotive Application

DOE PAGES

Szybist, James; Davis, Steven; Thomas, John; ...

2018-04-03

Thermoelectric generators (TEGs) have been researched and developed for harvesting energy from otherwise wasted heat. For automotive applications this will most likely involve using internal combustion engine exhaust as the heat source, with the TEG positioned after the catalyst system. Applications to exhaust gas recirculation systems and compressed air coolers have also been suggested. A thermoelectric generator based on half-Heusler thermoelectric materials was developed, engineered, and fabricated, targeting a gasoline passenger sedan application. This generator was installed on a gasoline engine exhaust system in a dynamometer cell, and positioned immediately downstream of the closecoupled three-way catalyst. The generator was characterizedmore » using a matrix of steady-state conditions representing the important portions of the engine map. Detailed performance results are presented. Measurements indicate the generator can produces over 300 W of power with 900 °C exhaust at relatively high flow rates, but less than 50 W when the exhaust is 600 °C and at lower flow rates. The latter condition is typical of standard test cycles and most driving scenarios.« less

Performance of a Half-Heusler Thermoelectric Generator for Automotive Application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Szybist, James; Davis, Steven; Thomas, John

Thermoelectric generators (TEGs) have been researched and developed for harvesting energy from otherwise wasted heat. For automotive applications this will most likely involve using internal combustion engine exhaust as the heat source, with the TEG positioned after the catalyst system. Applications to exhaust gas recirculation systems and compressed air coolers have also been suggested. A thermoelectric generator based on half-Heusler thermoelectric materials was developed, engineered, and fabricated, targeting a gasoline passenger sedan application. This generator was installed on a gasoline engine exhaust system in a dynamometer cell, and positioned immediately downstream of the closecoupled three-way catalyst. The generator was characterizedmore » using a matrix of steady-state conditions representing the important portions of the engine map. Detailed performance results are presented. Measurements indicate the generator can produces over 300 W of power with 900 °C exhaust at relatively high flow rates, but less than 50 W when the exhaust is 600 °C and at lower flow rates. The latter condition is typical of standard test cycles and most driving scenarios.« less

Waste heat generation: A comprehensive review.

PubMed

Yeşiller, Nazli; Hanson, James L; Yee, Emma H

2015-08-01

A comprehensive review of heat generation in various types of wastes and of the thermal regime of waste containment facilities is provided in this paper. Municipal solid waste (MSW), MSW incineration ash, and mining wastes were included in the analysis. Spatial and temporal variations of waste temperatures, thermal gradients, thermal properties of wastes, average temperature differentials, and heat generation values are provided. Heat generation was influenced by climatic conditions, mean annual earth temperatures, waste temperatures at the time of placement, cover conditions, and inherent heat generation potential of the specific wastes. Time to onset of heat generation varied between months and years, whereas timelines for overall duration of heat generation varied between years and decades. For MSW, measured waste temperatures were as high as 60-90°C and as low as -6°C. MSW incinerator ash temperatures varied between 5 and 87°C. Mining waste temperatures were in the range of -25 to 65°C. In the wastes analyzed, upward heat flow toward the surface was more prominent than downward heat flow toward the subsurface. Thermal gradients generally were higher for MSW and incinerator ash and lower for mining waste. Based on thermal properties, MSW had insulative qualities (low thermal conductivity), while mining wastes typically were relatively conductive (high thermal conductivity) with ash having intermediate qualities. Heat generation values ranged from -8.6 to 83.1MJ/m(3) and from 0.6 to 72.6MJ/m(3) for MSW and mining waste, respectively and was 72.6MJ/m(3) for ash waste. Conductive thermal losses were determined to range from 13 to 1111MJ/m(3)yr. The data and analysis provided in this review paper can be used in the investigation of heat generation and thermal regime of a wide range of wastes and waste containment facilities located in different climatic regions. Copyright © 2015 Elsevier Ltd. All rights reserved.

Technical Feasibility Evaluation on The Use of A Peltier Thermoelectric Module to Recover Automobile Exhaust Heat

NASA Astrophysics Data System (ADS)

Sugiartha, N.; Sastra Negara, P.

2018-01-01

A thermoelectric module composes of integrated p-n semiconductors as hot and cold side junctions and uses Seebeck effect between them to function as a thermoelectric generator (TEG) to directly convert heat into electrical power. Exhaust heat from engines as otherwise wasted to the atmosphere is one of the heat sources freely available to drive the TEG. This paper evaluates technical feasibility on the use of a Peltier thermoelectric module for energy recovery application of such kind of waste heat. An experimental apparatus has been setup to simulate real conditions of automobile engine exhaust piping system. It includes a square section aluminium ducting, an aluminium fin heat sink and a TEC1 12706 thermoelectric module. A heater and a cooling fan are employed to simulate hot exhaust gas and ambient air flows, respectively. Electrical loading is controlled by resistors. Dependent variables measured during the test are cold and hot side temperatures, open and loaded circuit output voltages and electrical current. The test results revealed a promising application of the Peltier thermoelectric module for the engine exhaust heat recovery, though the loaded output power produced and loaded output voltage are still far lower than the commercially thermoelectric module originally purposed for the TEG application.

NREL Reveals Potential for Capturing Waste Heat via Nanotubes | News | NREL

Science.gov Websites

Reveals Potential for Capturing Waste Heat via Nanotubes News Release: NREL Reveals Potential for Capturing Waste Heat via Nanotubes April 4, 2016 A finely tuned carbon nanotube thin film has the potential to act as a thermoelectric power generator that captures and uses waste heat, according to

Thermoelectric generator for motor vehicle

DOEpatents

Bass, John C.

1997-04-29

A thermoelectric generator for producing electric power for a motor vehicle from the heat of the exhaust gasses produced by the engine of the motor vehicle. The exhaust gasses pass through a finned heat transfer support structure which has seat positions on its outside surface for the positioning of thermoelectric modules. A good contact cylinder provides a framework from which a spring force can be applied to the thermoelectric modules to hold them in good contact on their seats on the surface of the heat transfer support structure.

Motorcycle waste heat energy harvesting

NASA Astrophysics Data System (ADS)

Schlichting, Alexander D.; Anton, Steven R.; Inman, Daniel J.

2008-03-01

Environmental concerns coupled with the depletion of fuel sources has led to research on ethanol, fuel cells, and even generating electricity from vibrations. Much of the research in these areas is stalling due to expensive or environmentally contaminating processes, however recent breakthroughs in materials and production has created a surge in research on waste heat energy harvesting devices. The thermoelectric generators (TEGs) used in waste heat energy harvesting are governed by the Thermoelectric, or Seebeck, effect, generating electricity from a temperature gradient. Some research to date has featured platforms such as heavy duty diesel trucks, model airplanes, and automobiles, attempting to either eliminate heavy batteries or the alternator. A motorcycle is another platform that possesses some very promising characteristics for waste heat energy harvesting, mainly because the exhaust pipes are exposed to significant amounts of air flow. A 1995 Kawasaki Ninja 250R was used for these trials. The module used in these experiments, the Melcor HT3-12-30, produced an average of 0.4694 W from an average temperature gradient of 48.73 °C. The mathematical model created from the Thermoelectric effect equation and the mean Seebeck coefficient displayed by the module produced an average error from the experimental data of 1.75%. Although the module proved insufficient to practically eliminate the alternator on a standard motorcycle, the temperature data gathered as well as the examination of a simple, yet accurate, model represent significant steps in the process of creating a TEG capable of doing so.

Integration of dye-sensitized solar cells, thermoelectric modules and electrical storage loop system to constitute a novel photothermoelectric generator.

PubMed

Chang, Ho; Yu, Zhi-Rong

2012-08-01

This study self-develops a novel type of photothermoelectric power generation modules. Dye-sensitized solar cells (DSSCs) serve as the photoelectric conversion system and a copper (Cu) heat-transfer nanofilm coating on both sides of the thermoelectric generator (TEG) acts as a thermoelectric conversion system. Thus module assembly absorbs light and generates electricity by DSSCs, and also recycles waste heat and generates power by the TEG. In addition, a set of pulsating heat pipes (PHP) filled with Cu nanofluid is placed on the cooling side to increase cooling effects and enhance the power generation efficiency. Results show that when the heat source of thermoelectric modules reaches 90 degrees C, TEG power output is increased by 85.7%. Besides, after thermoelectric modules are heated by additional heat source at 80 degrees C, the electrical energy generated by them can let a NiMH cell (1.25 V) be sufficiently charged in about 30 minutes. When photothermoelectric modules is illumined by simulated light, the temperature difference of two sides of TEG can reach 7 degrees C and the thermoelectric conversion efficiency is 2.17%. Furthermore, the power output of the thermoelectric modules is 11.48 mW/cm2, enhancing 1.4 % compared to merely using DSSCs module.

Modeling of a Thermoelectric Generator for Thermal Energy Regeneration in Automobiles

NASA Astrophysics Data System (ADS)

Tatarinov, Dimitri; Koppers, M.; Bastian, G.; Schramm, D.

2013-07-01

In the field of passenger transportation a reduction of the consumption of fossil fuels has to be achieved by any measures. Advanced designs of internal combustion engine have the potential to reduce CO2 emissions, but still suffer from low efficiencies in the range from 33% to 44%. Recuperation of waste heat can be achieved with thermoelectric generators (TEGs) that convert heat directly into electric energy, thus offering a less complicated setup as compared with thermodynamic cycle processes. During a specific driving cycle of a car, the heat currents and temperature levels of the exhaust gas are dynamic quantities. To optimize a thermoelectric recuperation system fully, various parameters have to be tested, for example, the electric and thermal conductivities of the TEG and consequently the heat absorbed and rejected from the system, the generated electrical power, and the system efficiency. A Simulink model consisting of a package for dynamic calculation of energy management in a vehicle, coupled with a model of the thermoelectric generator system placed on the exhaust system, determines the drive-cycle-dependent efficiency of the heat recovery system, thus calculating the efficiency gain of the vehicle. The simulation also shows the temperature drop at the heat exchanger along the direction of the exhaust flow and hence the variation of the voltage drop of consecutively arranged TEG modules. The connection between the temperature distribution and the optimal electrical circuitry of the TEG modules constituting the entire thermoelectric recuperation system can then be examined. The simulation results are compared with data obtained from laboratory experiments. We discuss error bars and the accuracy of the simulation results for practical thermoelectric systems embedded in cars.

Advanced Soldier Thermoelectric Power System for Power Generation from Battlefield Heat Sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hendricks, Terry J.; Hogan, Tim; Case, Eldon D.

2010-09-01

The U.S. military uses large amounts of fuel during deployments and battlefield operations. This project sought to develop a lightweight, small form-factor, soldier-portable advanced thermoelectric (TE) system prototype to recover and convert waste heat from various deployed military equipment (i.e., diesel generators/engines, incinerators, vehicles, and potentially mobile kitchens), with the ultimate purpose of producing power for soldier battery charging, advanced capacitor charging, and other battlefield power applications. The technical approach employed microchannel technology, a unique “power panel” approach to heat exchange/TE system integration, and newly-characterized LAST (lead-antimony-silver-telluride) and LASTT (lead-antimony-silver-tin-telluride) TE materials segmented with bismuth telluride TE materials in designingmore » a segmented-element TE power module and system. This project researched never-before-addressed system integration challenges (thermal expansion, thermal diffusion, electrical interconnection, thermal and electrical interfaces) of designing thin “power panels” consisting of alternating layers of thin, microchannel heat exchangers (hot and cold) sandwiching thin, segmented-element TE power generators. The TE properties, structurally properties, and thermal fatigue behavior of LAST and LASTT materials were developed and characterized such that the first segmented-element TE modules using LAST / LASTT materials were fabricated and tested at hot-side temperatures = 400 °C and cold-side temperatures = 40 °C. LAST / LASTT materials were successfully segmented with bismuth telluride and electrically interconnected with diffusion barrier materials and copper strapping within the module electrical circuit. A TE system design was developed to produce 1.5-1.6 kW of electrical energy using these new TE modules from the exhaust waste heat of 60-kW Tactical Quiet Generators as demonstration vehicles.« less

Discussion on the solar concentrating thermoelectric generation using micro-channel heat pipe array

NASA Astrophysics Data System (ADS)

Li, Guiqiang; Feng, Wei; Jin, Yi; Chen, Xiao; Ji, Jie

2017-11-01

Heat pipe is a high efficient tool in solar energy applications. In this paper, a novel solar concentrating thermoelectric generation using micro-channel heat pipe array (STEG-MCHP) was presented. The flat-plate micro-channel heat pipe array not only has a higher heat transfer performance than the common heat pipe, but also can be placed on the surface of TEG closely, which can further reduce the thermal resistance between the heat pipe and the TEG. A preliminary comparison experiment was also conducted to indicate the advantages of the STEG-MCHP. The optimization based on the model verified by the experiment was demonstrated, and the concentration ratio and selective absorbing coating area were also discussed. In addition, the cost analysis was also performed to compare between the STEG-MCHP and the common solar concentrating TEGs in series. The outcome showed that the solar concentrating thermoelectric generation using micro-channel heat pipe array has the higher electrical efficiency and lower cost, which may provide a suitable way for solar TEG applications.

Development and optimization of a stove-powered thermoelectric generator

NASA Astrophysics Data System (ADS)

Mastbergen, Dan

Almost a third of the world's population still lacks access to electricity. Most of these people use biomass stoves for cooking which produce significant amounts of wasted thermal energy, but no electricity. Less than 1% of this energy in the form of electricity would be adequate for basic tasks such as lighting and communications. However, an affordable and reliable means of accomplishing this is currently nonexistent. The goal of this work is to develop a thermoelectric generator to convert a small amount of wasted heat into electricity. Although this concept has been around for decades, previous attempts have failed due to insufficient analysis of the system as a whole, leading to ineffective and costly designs. In this work, a complete design process is undertaken including concept generation, prototype testing, field testing, and redesign/optimization. Detailed component models are constructed and integrated to create a full system model. The model encompasses the stove operation, thermoelectric module, heat sinks, charging system and battery. A 3000 cycle endurance test was also conducted to evaluate the effects of operating temperature, module quality, and thermal interface quality on the generator's reliability, lifetime and cost effectiveness. The results from this testing are integrated into the system model to determine the lowest system cost in $/Watt over a five year period. Through this work the concept of a stove-based thermoelectric generator is shown to be technologically and economically feasible. In addition, a methodology is developed for optimizing the system for specific regional stove usage habits.

A Review on Electroactive Polymers for Waste Heat Recovery.

PubMed

Kolasińska, Ewa; Kolasiński, Piotr

2016-06-17

This paper reviews materials for thermoelectric waste heat recovery, and discusses selected industrial and distributed waste heat sources as well as recovery methods that are currently applied. Thermoelectric properties, especially electrical conductivity, thermopower, thermal conductivity and the thermoelectric figures of merit, are considered when evaluating thermoelectric materials for waste heat recovery. Alloys and oxides are briefly discussed as materials suitable for medium- and high-grade sources. Electroactive polymers are presented as a new group of materials for low-grade sources. Polyaniline is a particularly fitting polymer for these purposes. We also discuss types of modifiers and modification methods, and their influence on the thermoelectric performance of this class of polymers.

Silicon-Based Thermoelectrics: Harvesting Low Quality Heat Using Economically Printed Flexible Nanostructured Stacked Thermoelectric Junctions

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

2010-03-01

Broad Funding Opportunity Announcement Project: UIUC is experimenting with silicon-based materials to develop flexible thermoelectric devices—which convert heat into energy—that can be mass-produced at low cost. A thermoelectric device, which resembles a computer chip, creates electricity when a different temperature is applied to each of its sides. Existing commercial thermoelectric devices contain the element tellurium, which limits production levels because tellurium has become increasingly rare. UIUC is replacing this material with microscopic silicon wires that are considerably cheaper and could be equally effective. Improvements in thermoelectric device production could return enough wasted heat to add up to 23% to ourmore » current annual electricity production.« less

A Review on Electroactive Polymers for Waste Heat Recovery

PubMed Central

Kolasińska, Ewa; Kolasiński, Piotr

2016-01-01

This paper reviews materials for thermoelectric waste heat recovery, and discusses selected industrial and distributed waste heat sources as well as recovery methods that are currently applied. Thermoelectric properties, especially electrical conductivity, thermopower, thermal conductivity and the thermoelectric figures of merit, are considered when evaluating thermoelectric materials for waste heat recovery. Alloys and oxides are briefly discussed as materials suitable for medium- and high-grade sources. Electroactive polymers are presented as a new group of materials for low-grade sources. Polyaniline is a particularly fitting polymer for these purposes. We also discuss types of modifiers and modification methods, and their influence on the thermoelectric performance of this class of polymers. PMID:28773605

Studies on Effective Utilization of SOFC Exhaust Heat Using Thermoelectric Power Generation Technology

NASA Astrophysics Data System (ADS)

Terayama, Takeshi; Nagata, Susumu; Tanaka, Yohei; Momma, Akihiko; Kato, Tohru; Kunii, Masaru; Yamamoto, Atsushi

2013-07-01

Solid oxide fuel cells (SOFCs) are being researched around the world. In Japan, a compact SOFC system with rated alternative current (AC) power of 700 W has become available on the market, since the base load electricity demand for a standard home is said to be less than 700 W AC. To improve the generating efficiency of SOFC systems in the 700-W class, we focused on thermoelectric generation (TEG) technology, since there are a lot of temperature gradients in the system. Analysis based on simulations indicated the possibility of introducing thermoelectric generation at the air preheater, steam generator, and exhaust outlet. Among these options, incorporating a TEG heat exchanger comprising multiple CoSb3/SiGe-based TEG modules into the air preheater had potential to produce additional output of 37.5 W and an improvement in generating efficiency from 46% to 48.5%. Furthermore, by introducing thermoelectric generation at the other two locations, an increase in maximum output of more than 50 W and generating efficiency of 50% can be anticipated.

Thermoelectric generator

DOEpatents

Pryslak, N.E.

1974-02-26

A thermoelectric generator having a rigid coupling or stack'' between the heat source and the hot strap joining the thermoelements is described. The stack includes a member of an insulating material, such as ceramic, for electrically isolating the thermoelements from the heat source, and a pair of members of a ductile material, such as gold, one each on each side of the insulating member, to absorb thermal differential expansion stresses in the stack. (Official Gazette)

Prototype Combined Heater/Thermoelectric Power Generator for Remote Applications

NASA Astrophysics Data System (ADS)

Champier, D.; Favarel, C.; Bédécarrats, J. P.; Kousksou, T.; Rozis, J. F.

2013-07-01

This study presents a prototype thermoelectric generator (TEG) developed for remote applications in villages that are not connected to the electrical power grid. For ecological and economic reasons, there is growing interest in harvesting waste heat from biomass stoves to produce some electricity. Because regular maintenance is not required, TEGs are an attractive choice for small-scale power generation in inaccessible areas. The prototype developed in our laboratory is especially designed to be implemented in stoves that are also used for domestic hot water heating. The aim of this system is to provide a few watts to householders, so they have the ability to charge cellular phones and radios, and to get some light at night. A complete prototype TEG using commercial (bismuth telluride) thermoelectric modules has been built, including system integration with an electric DC/DC converter. The DC/DC converter has a maximum power point tracker (MPPT) driven by an MC9SO8 microcontroller, which optimizes the electrical energy stored in a valve-regulated lead-acid battery. Physical models were used to study the behavior of the thermoelectric system and to optimize the performance of the MPPT. Experiments using a hot gas generator to simulate the exhaust of the combustion chamber of a stove are used to evaluate the system. Additionally, potential uses of such generators are presented.

Effect of Topology Structure on the Output Performance of an Automobile Exhaust Thermoelectric Generator

NASA Astrophysics Data System (ADS)

Fang, W.; Quan, S. H.; Xie, C. J.; Ran, B.; Li, X. L.; Wang, L.; Jiao, Y. T.; Xu, T. W.

2017-05-01

The majority of the thermal energy released in an automotive internal combustion cycle is exhausted as waste heat through the tail pipe. This paper describes an automobile exhaust thermoelectric generator (AETEG), designed to recycle automobile waste heat. A model of the output characteristics of each thermoelectric device was established by testing their open circuit voltage and internal resistance, and combining the output characteristics. To better describe the relationship, the physical model was transformed into a topological model. The connection matrix was used to describe the relationship between any two thermoelectric devices in the topological structure. Different topological structures produced different power outputs; their output power was maximised by using an iterative algorithm to optimize the series-parallel electrical topology structure. The experimental results have shown that the output power of the optimal topology structure increases by 18.18% and 29.35% versus that of a pure in-series or parallel topology, respectively, and by 10.08% versus a manually defined structure (based on user experience). The thermoelectric conversion device increased energy efficiency by 40% when compared with a traditional car.

New Technology for Microfabrication and Testing of a Thermoelectric Device for Generating Mobile Electrical Power

NASA Technical Reports Server (NTRS)

Prasad, Narasimha S.; Taylor, Patrick J.; Trivedi, Sudhir B.; Kutcher, Susan

2012-01-01

Thermoelectric (TE) power generation is an increasingly important power generation technology. Major advantages include: no moving parts, low-weight, modularity, covertness/silence, high power density, low amortized cost, and long service life with minimum or no required maintenance. Despite low efficiency of power generation, there are many specialized needs for electrical power that TE technologies can uniquely and successfully address. Recent advances in thermoelectric materials technology have rekindled acute interest in thermoelectric power generation. We have developed single crystalline n- and p- type PbTe crystals and are also, developing PbTe bulk nanocomposites using PbTe nano powders and emerging filed assisted sintering technology (FAST). We will discuss the materials requirements for efficient thermoelectric power generation using waste heat at intermediate temperature range (6500 to 8500 K). We will present our recent results on production of n- and p- type PbTe crystals and their thermoelectric characterization. Relative characteristics and performance of PbTe bulk single crystals and nano composites for thermoelectric power generation will be discussed.

Utilizing Radioisotope Power System Waste Heat for Spacecraft Thermal Management

NASA Technical Reports Server (NTRS)

Pantano, David R.; Dottore, Frank; Tobery, E. Wayne; Geng, Steven M.; Schreiber, Jeffrey G.; Palko, Joseph L.

2005-01-01

An advantage of using a Radioisotope Power System (RPS) for deep space or planetary surface missions is the readily available waste heat, which can be used for a number of beneficial purposes including: maintaining electronic components within a controlled temperature range, warming propulsion tanks and mobility actuators, and maintaining liquid propellants above their freezing temperature. Previous missions using Radioisotope Thermoelectric Generators (RTGs) dissipated large quantities of waste heat due to the low efficiency of the thermoelectric conversion technology. The next generation RPSs, such as the 110-Watt Stirling Radioisotope Generator (SRG110) will have higher conversion efficiencies, thereby rejecting less waste heat at a lower temperature and may require alternate approaches to transferring waste heat to the spacecraft. RTGs, with efficiencies of 6 to 7 percent, reject their waste heat at the relatively high heat rejection temperature of 200 C. This is an advantage when rejecting heat to space; however, transferring heat to the internal spacecraft components requires a large and heavy radiator heat exchanger. At the same time, sensitive spacecraft instruments must be shielded from the thermal radiation of the RTG. The SRG110, with an efficiency around 22 percent and 50 C nominal housing surface temperature, can readily transfer the available waste heat directly via heat pipes, thermal straps, or fluid loops. The lower temperatures associated with the SRG110 avoid the chances of overheating other scientific components, eliminating the need for thermal shields. This provides the spacecraft designers more flexibility when locating the generator for a specific mission. A common misconception with high-efficiency systems is that there is not enough waste heat for spacecraft thermal management. This paper will dispel this misconception and investigate the use of a high-efficiency SRG110 for spacecraft thermal management and outline potential methods of

Computer modeling of thermoelectric generator performance

NASA Technical Reports Server (NTRS)

Chmielewski, A. B.; Shields, V.

1982-01-01

Features of the DEGRA 2 computer code for simulating the operations of a spacecraft thermoelectric generator are described. The code models the physical processes occurring during operation. Input variables include the thermoelectric couple geometry and composition, the thermoelectric materials' properties, interfaces and insulation in the thermopile, the heat source characteristics, mission trajectory, and generator electrical requirements. Time steps can be specified and sublimation of the leg and hot shoe is accounted for, as are shorts between legs. Calculations are performed for conduction, Peltier, Thomson, and Joule heating, the cold junction can be adjusted for solar radition, and the legs of the thermoelectric couple are segmented to enhance the approximation accuracy. A trial run covering 18 couple modules yielded data with 0.3% accuracy with regard to test data. The model has been successful with selenide materials, SiGe, and SiN4, with output of all critical operational variables.

Thermoelectric heat exchange element

DOEpatents

Callas, James J.; Taher, Mahmoud A.

2007-08-14

A thermoelectric heat exchange module includes a first substrate including a heat receptive side and a heat donative side and a series of undulatory pleats. The module may also include a thermoelectric material layer having a ZT value of 1.0 or more disposed on at least one of the heat receptive side and the heat donative side, and an electrical contact may be in electrical communication with the thermoelectric material layer.

Near-field three-terminal thermoelectric heat engine

NASA Astrophysics Data System (ADS)

Jiang, Jian-Hua; Imry, Yoseph

2018-03-01

We propose a near-field inelastic thermoelectric heat engine where quantum dots are used to effectively rectify the charge flow of photocarriers. The device converts near-field heat radiation into useful electrical power. Heat absorption and inelastic transport can be enhanced by introducing two continuous spectra separated by an energy gap. The thermoelectric transport properties of the heat engine are studied in the linear-response regime. Using a small band-gap semiconductor as the absorption material, we show that the device achieves very large thermopower and thermoelectric figure of merit, as well as considerable power factor. By analyzing thermal-photocarrier generation and conduction, we reveal that the Seebeck coefficient and the figure of merit have oscillatory dependence on the thickness of the vacuum gap. Meanwhile, the power factor, the charge, and thermal conductivity are significantly improved by near-field radiation. Conditions and guiding principles for powerful and efficient thermoelectric heat engines are discussed in details.

Specification for strontium-90 500-watt(e) radioisotopic thermoelectric generator

NASA Astrophysics Data System (ADS)

Hammel, T.; Himes, J.; Lieberman, A.; McGrew, J. W.; Owings, D.; Schumann, F.

1983-04-01

A conceptual design for a demonstration 500-watt(e) radioisotopic thermoelectric generator (RTG) was created. The design effort was divided into two tasks, viz., create a design specification for a capsule strenth member that utilizes a standard Strontium 90 fluoride filled WESF inner liner, and create a conceptual design for a 500-watt(e) RTG. The strength member specification was designed to survive an external pressure of 24,500 psi and meet the requirements of special form radioisotope heat sources. Therefore the capsule is if desired, licensed for domestic and international transport. The design for the RTG features a radioisotopic heat source, an array of nine capsules in a tungsten biological shield, four current technology series connected thermoelectric conversion modules, low conductivity thermal insulation, and a passive finned housing radiator for waste heat dissipation. The preliminary RTG specification formulated previous to contract award was met or exceeded.

New device architecture of a thermoelectric energy conversion for recovering low-quality heat

NASA Astrophysics Data System (ADS)

Kim, Hoon; Park, Sung-Geun; Jung, Buyoung; Hwang, Junphil; Kim, Woochul

2014-03-01

Low-quality heat is generally discarded for economic reasons; a low-cost energy conversion device considering price per watt, /W, is required to recover this waste heat. Thin-film based thermoelectric devices could be a superior alternative for this purpose, based on their low material consumption; however, power generated in conventional thermoelectric device architecture is negligible due to the small temperature drop across the thin film. To overcome this challenge, we propose new device architecture, and demonstrate approximately 60 Kelvin temperature differences using a thick polymer nanocomposite. The temperature differences were achieved by separating the thermal path from the electrical path; whereas in conventional device architecture, both electrical charges and thermal energy share same path. We also applied this device to harvest body heat and confirmed its usability as an energy conversion device for recovering low-quality heat.

Utilizing Radioisotope Power System Waste Heat for Spacecraft Thermal Management

NASA Technical Reports Server (NTRS)

Pantano, David R.; Dottore, Frank; Geng, Steven M.; Schrieber, Jeffrey G.; Tobery, E. Wayne; Palko, Joseph L.

2005-01-01

One of the advantages of using a Radioisotope Power System (RPS) for deep space or planetary surface missions is the readily available waste heat, which can be used to maintain electronic components within a controlled temperature range, to warm propulsion tanks and mobility actuators, and to gasify liquid propellants. Previous missions using Radioisotope Thermoelectric Generators (RTGs) dissipated a very large quantity of waste heat due to the relatively low efficiency of the thermoelectric conversion technology. The next generation RPSs, such as the 110-watt Stirling Radioisotope Generator (SRG110) will have much higher conversion efficiencies than their predecessors and therefore may require alternate approaches to transferring waste heat to the spacecraft. RTGs, with efficiencies of approx. 6 to 7% and 200 C housing surface temperatures, would need to use large and heavy radiator heat exchangers to transfer the waste heat to the internal spacecraft components. At the same time, sensitive spacecraft instruments must be shielded from the thermal radiation by using the heat exchangers or additional shields. The SRG110, with an efficiency around 22% and 50 C nominal housing surface temperature, can use the available waste heat more efficiently by more direct heat transfer methods such as heat pipes, thermal straps, or fluid loops. The lower temperatures allow the SRG110 much more flexibility to the spacecraft designers in configuring the generator without concern of overheating nearby scientific instruments, thereby eliminating the need for thermal shields. This paper will investigate using a high efficiency SRG110 for spacecraft thermal management and outline potential methods in several conceptual missions (Lunar Rover, Mars Rover, and Titan Lander) to illustrate the advantages with regard to ease of assembly, less complex interfaces, and overall mass savings.

Computational Analysis of a Thermoelectric Generator for Waste-Heat Harvesting in Wearable Systems

NASA Astrophysics Data System (ADS)

Kossyvakis, D. N.; Vassiliadis, S. G.; Vossou, C. G.; Mangiorou, E. E.; Potirakis, S. M.; Hristoforou, E. V.

2016-06-01

Over recent decades, a constantly growing interest in the field of portable electronic devices has been observed. Recent developments in the scientific areas of integrated circuits and sensing technologies have enabled realization and design of lightweight low-power wearable sensing systems that can be of great use, especially for continuous health monitoring and performance recording applications. However, to facilitate wide penetration of such systems into the market, the issue of ensuring their seamless and reliable power supply still remains a major concern. In this work, the performance of a thermoelectric generator, able to exploit the temperature difference established between the human body and the environment, has been examined computationally using ANSYS 14.0 finite-element modeling (FEM) software, as a means for providing the necessary power to various portable electronic systems. The performance variation imposed due to different thermoelement geometries has been estimated to identify the most appropriate solution for the considered application. Furthermore, different ambient temperature and heat exchange conditions between the cold side of the generator and the environment have been investigated. The computational analysis indicated that power output in the order of 1.8 mW can be obtained by a 100-cm2 system, if specific design criteria can be fulfilled.

Optimized Characterization of Thermoelectric Generators for Automotive Application

NASA Astrophysics Data System (ADS)

Tatarinov, Dimitri; Wallig, Daniel; Bastian, Georg

2012-06-01

New developments in the field of thermoelectric materials bring the prospect of consumer devices for recovery of some of the waste heat from internal combustion engines closer to reality. Efficiency improvements are expected due to the development of high-temperature thermoelectric generators (TEG). In contrast to already established radioisotope thermoelectric generators, the temperature difference in automotive systems is not constant, and this imposes a set of specific requirements on the TEG system components. In particular, the behavior of the TEGs and interface materials used to link the heat flow from the heat source through the TEG to the heat sink must be examined. Due to the usage patterns of automobiles, the TEG will be subject to cyclic thermal loads, which leads to module degradation. Additionally, the automotive TEG will be exposed to an inhomogeneous temperature distribution, leading to inhomogeneous mechanical loads and reduced system efficiency. Therefore, a characterization rig is required to allow determination of the electrical, thermal, and mechanical properties of such high-temperature TEG systems. This paper describes a measurement setup using controlled adjustment of cold-side and warm-side temperatures as well as controlled feed-in of electrical power for evaluation of TEGs for application in vehicles with combustion engines. The temperature profile in the setup can be varied to simulate any vehicle usage pattern, such as the European standard driving cycle, allowing the power yield of the TEGs to be evaluated for the chosen cycle. The spatially resolved temperature distribution of a TEG system can be examined by thermal imaging. Hotspots or cracks on thermocouples of the TEGs and the thermal resistance of thermal interface materials can also be examined using this technology. The construction of the setup is briefly explained, followed by detailed discussion of the experimental results.

Superconducting thermoelectric generator

DOEpatents

Metzger, J.D.; El-Genk, M.S.

1996-01-01

An apparatus and method for producing electricity from heat. The present invention is a thermoelectric generator that uses materials with substantially no electrical resistance, often called superconductors, to efficiently convert heat into electrical energy without resistive losses. Preferably, an array of superconducting elements is encased within a second material with a high thermal conductivity. The second material is preferably a semiconductor. Alternatively, the superconducting material can be doped on a base semiconducting material, or the superconducting material and the semiconducting material can exist as alternating, interleaved layers of waferlike materials. A temperature gradient imposed across the boundary of the two materials establishes an electrical potential related to the magnitude of the temperature gradient. The superconducting material carries the resulting electrical current at zero resistivity, thereby eliminating resistive losses. The elimination of resistive losses significantly increases the conversion efficiency of the thermoelectric device.

Superconducting thermoelectric generator

DOEpatents

Metzger, John D.; El-Genk, Mohamed S.

1998-01-01

An apparatus and method for producing electricity from heat. The present invention is a thermoelectric generator that uses materials with substantially no electrical resistance, often called superconductors, to efficiently convert heat into electrical energy without resistive losses. Preferably, an array of superconducting elements is encased within a second material with a high thermal conductivity. The second material is preferably a semiconductor. Alternatively, the superconducting material can be doped on a base semiconducting material, or the superconducting material and the semiconducting material can exist as alternating, interleaved layers of waferlike materials. A temperature gradient imposed across the boundary of the two materials establishes an electrical potential related to the magnitude of the temperature gradient. The superconducting material carries the resulting electrical current at zero resistivity, thereby eliminating resistive losses. The elimination of resistive losses significantly increases the conversion efficiency of the thermoelectric device.

Fiber optic signal amplifier using thermoelectric power generation

DOEpatents

Hart, M.M.

1993-01-01

A remote fiber optic signal amplifier for use as a repeater/amplifier, such as in transoceanic communication, powered by a Pu{sub 238} or Sr{sub 90} thermoelectric generator. The amplifier comprises a unit with connections on the receiving and sending sides of the communications system, and an erbium-doped fiber amplifier connecting each sending fiber to each receiving fiber. The thermoelectric generator, preferably a Pu{sub 238} or Sr{sub 90} thermoelectric generator delivers power to the amplifiers through a regulator. The heat exchange surfaces of the thermoelectric generator are made of material resistant to corrosion and biological growth and are directly exposed to the outside, such as the ocean water in transoceanic communications.

Fiber optic signal amplifier using thermoelectric power generation

DOEpatents

Hart, M.M.

1995-04-18

A remote fiber optic signal amplifier for use as a repeater/amplifier, such as in transoceanic communications, powered by a Pu{sub 238} or Sr{sub 90} thermoelectric generator. The amplifier comprises a unit with connections on the receiving and sending sides of the communications system, and an erbium-doped fiber amplifier connecting each sending fiber to each receiving fiber. The thermoelectric generator, preferably a Pu{sub 238} or Sr{sub 90} thermoelectric generator delivers power to the amplifiers through a regulator. The heat exchange surfaces of the thermoelectric generator are made of materials resistant to corrosion and biological growth and are directly exposed to the outside, such as the ocean water in transoceanic communications. 2 figs.

Fiber optic signal amplifier using thermoelectric power generation

DOEpatents

Hart, Mark M.

1995-01-01

A remote fiber optic signal amplifier for use as a repeater/amplifier, such as in transoceanic communications, powered by a Pu.sub.238 or Sr.sub.90 thermoelectric generator. The amplifier comprises a unit with connections on the receiving and sending sides of the communications system, and an erbium-doped fiber amplifier connecting each sending fiber to each receiving fiber. The thermoelectric generator, preferably a Pu.sub.238 or Sr.sub.90 thermoelectric generator delivers power to the amplifiers through a regulator. The heat exchange surfaces of the thermoelectric generator are made of materials resistant to corrosion and biological growth and are directly exposed to the outside, such as the ocean water in transoceanic communications.

Thermoelectric energy harvesting for a solid waste processing toilet

NASA Astrophysics Data System (ADS)

Stokes, C. David; Baldasaro, Nicholas G.; Bulman, Gary E.; Stoner, Brian R.

2014-06-01

Over 2.5 billion people do not have access to safe and effective sanitation. Without a sanitary sewer infrastructure, self-contained modular systems can provide solutions for these people in the developing world and remote areas. Our team is building a better toilet that processes human waste into burnable fuel and disinfects the liquid waste. The toilet employs energy harvesting to produce electricity and does not require external electrical power or consumable materials. RTI has partnered with Colorado State University, Duke University, and Roca Sanitario under a Bill and Melinda Gates Foundation Reinvent the Toilet Challenge (RTTC) grant to develop an advanced stand-alone, self-sufficient toilet to effectively process solid and liquid waste. The system operates through the following steps: 1) Solid-liquid separation, 2) Solid waste drying and sizing, 3) Solid waste combustion, and 4) Liquid waste disinfection. Thermoelectric energy harvesting is a key component to the system and provides the electric power for autonomous operation. A portion of the exhaust heat is captured through finned heat-sinks and converted to electricity by thermoelectric (TE) devices to provide power for the electrochemical treatment of the liquid waste, pumps, blowers, combustion ignition, and controls.

Laser-powered thermoelectric generators operating at cryogenic temperatures

NASA Astrophysics Data System (ADS)

Harutyunyan, S. R.; Vardanyan, V. H.; Kuzanyan, A. S.; Nikoghosyan, V. R.; Kunii, S.; Winzer, K.; Wood, K. S.; Gulian, A. M.

2005-11-01

A thermoelectric generator, operating in a cryostat at liquid helium temperatures, is described. Energy to the generator is supplied via an external laser beam. For this prototype device the associated heat load at permanent operation is comparable with the heat load associated with power delivery via metallic wires. Estimates indicate that still better performance can be enabled with existing thermoelectric materials, thereby far exceeding efficiency of traditional cryostat wiring. We used a prototype generator to produce electric power for measuring critical currents in Nb3Sn-films at 4K.

Collection of low-grade waste heat for enhanced energy harvesting

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dede, Ercan M., E-mail: eric.dede@tema.toyota.com; Schmalenberg, Paul; Wang, Chi-Ming

Enhanced energy harvesting through the collection of low-grade waste heat is experimentally demonstrated. A structural optimization technique is exploited in the design of a thermal-composite substrate to guide and gather the heat emanating from multiple sources to a predetermined location. A thermoelectric generator is then applied at the selected focusing region to convert the resulting low-grade waste heat to electrical power. The thermal characteristics of the device are experimentally verified by direct temperature measurements of the system and numerically validated via heat conduction simulations. Electrical performance under natural and forced convection is measured, and in both cases, the device withmore » optimized heat flow control plus energy harvesting demonstrates increased power generation when compared with a baseline waste heat recovery system. Electronics applications include energy scavenging for autonomously powered sensor networks or self-actuated devices.« less

Miniaturized planar Si-nanowire micro-thermoelectric generator using exuded thermal field for power generation.

PubMed

Zhan, Tianzhuo; Yamato, Ryo; Hashimoto, Shuichiro; Tomita, Motohiro; Oba, Shunsuke; Himeda, Yuya; Mesaki, Kohei; Takezawa, Hiroki; Yokogawa, Ryo; Xu, Yibin; Matsukawa, Takashi; Ogura, Atsushi; Kamakura, Yoshinari; Watanabe, Takanobu

2018-01-01

For harvesting energy from waste heat, the power generation densities and fabrication costs of thermoelectric generators (TEGs) are considered more important than their conversion efficiency because waste heat energy is essentially obtained free of charge. In this study, we propose a miniaturized planar Si-nanowire micro-thermoelectric generator (SiNW-μTEG) architecture, which could be simply fabricated using the complementary metal-oxide-semiconductor-compatible process. Compared with the conventional nanowire μTEGs, this SiNW-μTEG features the use of an exuded thermal field for power generation. Thus, there is no need to etch away the substrate to form suspended SiNWs, which leads to a low fabrication cost and well-protected SiNWs. We experimentally demonstrate that the power generation density of the SiNW-μTEGs was enhanced by four orders of magnitude when the SiNWs were shortened from 280 to 8 μm. Furthermore, we reduced the parasitic thermal resistance, which becomes significant in the shortened SiNW-μTEGs, by optimizing the fabrication process of AlN films as a thermally conductive layer. As a result, the power generation density of the SiNW-μTEGs was enhanced by an order of magnitude for reactive sputtering as compared to non-reactive sputtering process. A power density of 27.9 nW/cm 2 has been achieved. By measuring the thermal conductivities of the two AlN films, we found that the reduction in the parasitic thermal resistance was caused by an increase in the thermal conductivity of the AlN film and a decrease in the thermal boundary resistance.

Miniaturized planar Si-nanowire micro-thermoelectric generator using exuded thermal field for power generation

PubMed Central

Zhan, Tianzhuo; Yamato, Ryo; Hashimoto, Shuichiro; Tomita, Motohiro; Oba, Shunsuke; Himeda, Yuya; Mesaki, Kohei; Takezawa, Hiroki; Yokogawa, Ryo; Xu, Yibin; Matsukawa, Takashi; Ogura, Atsushi; Kamakura, Yoshinari; Watanabe, Takanobu

2018-01-01

Abstract For harvesting energy from waste heat, the power generation densities and fabrication costs of thermoelectric generators (TEGs) are considered more important than their conversion efficiency because waste heat energy is essentially obtained free of charge. In this study, we propose a miniaturized planar Si-nanowire micro-thermoelectric generator (SiNW-μTEG) architecture, which could be simply fabricated using the complementary metal–oxide–semiconductor–compatible process. Compared with the conventional nanowire μTEGs, this SiNW-μTEG features the use of an exuded thermal field for power generation. Thus, there is no need to etch away the substrate to form suspended SiNWs, which leads to a low fabrication cost and well-protected SiNWs. We experimentally demonstrate that the power generation density of the SiNW-μTEGs was enhanced by four orders of magnitude when the SiNWs were shortened from 280 to 8 μm. Furthermore, we reduced the parasitic thermal resistance, which becomes significant in the shortened SiNW-μTEGs, by optimizing the fabrication process of AlN films as a thermally conductive layer. As a result, the power generation density of the SiNW-μTEGs was enhanced by an order of magnitude for reactive sputtering as compared to non-reactive sputtering process. A power density of 27.9 nW/cm2 has been achieved. By measuring the thermal conductivities of the two AlN films, we found that the reduction in the parasitic thermal resistance was caused by an increase in the thermal conductivity of the AlN film and a decrease in the thermal boundary resistance. PMID:29868148

RTG Waste Heat System for the Cassini Propulsion Module

NASA Technical Reports Server (NTRS)

Mireles, V.; Stultz, J.

1994-01-01

This paper describes the thermal design for the propulsion module subsystem (PMS), and presents the results from the radioisotope thermoelectric generator (RTG) waste heat thermal test, and it summarizes the adjustment techniques and their relative effectiveness; it also shows the resulting predicted PMS flight temperatures relative to the requirements.

Superconducting thermoelectric generator

DOEpatents

Metzger, J.D.; El-Genk, M.S.

1998-05-05

An apparatus and method for producing electricity from heat is disclosed. The present invention is a thermoelectric generator that uses materials with substantially no electrical resistance, often called superconductors, to efficiently convert heat into electrical energy without resistive losses. Preferably, an array of superconducting elements is encased within a second material with a high thermal conductivity. The second material is preferably a semiconductor. Alternatively, the superconducting material can be doped on a base semiconducting material, or the superconducting material and the semiconducting material can exist as alternating, interleaved layers of waferlike materials. A temperature gradient imposed across the boundary of the two materials establishes an electrical potential related to the magnitude of the temperature gradient. The superconducting material carries the resulting electrical current at zero resistivity, thereby eliminating resistive losses. The elimination of resistive losses significantly increases the conversion efficiency of the thermoelectric device. 4 figs.

Multi-Mission Radioisotope Thermoelectric Generator Heat Exchangers for the Mars Science Laboratory Rover

NASA Technical Reports Server (NTRS)

Mastropietro, A. J.; Beatty, John S.; Kelly, Frank P.; Bhandari, Pradeep; Bame, David P.; Liu, Yuanming; Birux, Gajanana C.; Miller, Jennifer R.; Pauken, Michael T.; Illsley, Peter M.

2012-01-01

The addition of the Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) to the Mars Science Laboratory (MSL) Rover requires an advanced thermal control system that is able to both recover and reject the waste heat from the MMRTG as needed in order to maintain the onboard electronics at benign temperatures despite the extreme and widely varying environmental conditions experienced both on the way to Mars and on the Martian surface. Based on the previously successful Mars landed mission thermal control schemes, a mechanically pumped fluid loop (MPFL) architecture was selected as the most robust and efficient means for meeting the MSL thermal requirements. The MSL heat recovery and rejection system (HRS) is comprised of two Freon (CFC-11) MPFLs that interact closely with one another to provide comprehensive thermal management throughout all mission phases. The first loop, called the Rover HRS (RHRS), consists of a set of pumps, thermal control valves, and heat exchangers (HXs) that enables the transport of heat from the MMRTG to the rover electronics during cold conditions or from the electronics straight to the environment for immediate heat rejection during warm conditions. The second loop, called the Cruise HRS (CHRS), is thermally coupled to the RHRS during the cruise to Mars, and provides a means for dissipating the waste heat more directly from the MMRTG as well as from both the cruise stage and rover avionics by promoting circulation to the cruise stage radiators. A multifunctional structure was developed that is capable of both collecting waste heat from the MMRTG and rejecting the waste heat to the surrounding environment. It consists of a pair of honeycomb core sandwich panels with HRS tubes bonded to both sides. Two similar HX assemblies were designed to surround the MMRTG on the aft end of the rover. Heat acquisition is accomplished on the interior (MMRTG facing) surface of each HX while heat rejection is accomplished on the exterior surface of

Object-Oriented Modeling of an Energy Harvesting System Based on Thermoelectric Generators

NASA Astrophysics Data System (ADS)

Nesarajah, Marco; Frey, Georg

This paper deals with the modeling of an energy harvesting system based on thermoelectric generators (TEG), and the validation of the model by means of a test bench. TEGs are capable to improve the overall energy efficiency of energy systems, e.g. combustion engines or heating systems, by using the remaining waste heat to generate electrical power. Previously, a component-oriented model of the TEG itself was developed in Modelica® language. With this model any TEG can be described and simulated given the material properties and the physical dimension. Now, this model was extended by the surrounding components to a complete model of a thermoelectric energy harvesting system. In addition to the TEG, the model contains the cooling system, the heat source, and the power electronics. To validate the simulation model, a test bench was built and installed on an oil-fired household heating system. The paper reports results of the measurements and discusses the validity of the developed simulation models. Furthermore, the efficiency of the proposed energy harvesting system is derived and possible improvements based on design variations tested in the simulation model are proposed.

Thermoelectric Energy Conversion: Future Directions and Technology Development Needs

NASA Technical Reports Server (NTRS)

Fleurial, Jean-Pierre

2007-01-01

This viewgraph presentation reviews the process of thermoelectric energy conversion along with key technology needs and challenges. The topics include: 1) The Case for Thermoelectrics; 2) Advances in Thermoelectrics: Investment Needed; 3) Current U.S. Investment (FY07); 4) Increasing Thermoelectric Materials Conversion Efficiency Key Science Needs and Challenges; 5) Developing Advanced TE Components & Systems Key Technology Needs and Challenges; 6) Thermoelectrics; 7) 200W Class Lightweight Portable Thermoelectric Generator; 8) Hybrid Absorption Cooling/TE Power Cogeneration System; 9) Major Opportunities in Energy Industry; 10) Automobile Waste Heat Recovery; 11) Thermoelectrics at JPL; 12) Recent Advances at JPL in Thermoelectric Converter Component Technologies; 13) Thermoelectrics Background on Power Generation and Cooling Operational Modes; 14) Thermoelectric Power Generation; and 15) Thermoelectric Cooling.

Efficient p-n junction-based thermoelectric generator that can operate at extreme temperature conditions

NASA Astrophysics Data System (ADS)

Chavez, Ruben; Angst, Sebastian; Hall, Joseph; Maculewicz, Franziska; Stoetzel, Julia; Wiggers, Hartmut; Thanh Hung, Le; Van Nong, Ngo; Pryds, Nini; Span, Gerhard; Wolf, Dietrich E.; Schmechel, Roland; Schierning, Gabi

2018-01-01

In many industrial processes, a large proportion of energy is lost in the form of heat. Thermoelectric generators can convert this waste heat into electricity by means of the Seebeck effect. However, the use of thermoelectric generators in practical applications on an industrial scale is limited in part because electrical, thermal, and mechanical bonding contacts between the semiconductor materials and the metal electrodes in current designs are not capable of withstanding thermal-mechanical stress and alloying of the metal-semiconductor interface when exposed to the high temperatures occurring in many real-world applications. Here we demonstrate a concept for thermoelectric generators that can address this issue by replacing the metallization and electrode bonding on the hot side of the device by a p-n junction between the two semiconductor materials, making the device robust against temperature induced failure. In our proof-of-principle demonstration, a p-n junction device made from nanocrystalline silicon is at least comparable in its efficiency and power output to conventional devices of the same material and fabrication process, but with the advantage of sustaining high hot side temperatures and oxidative atmosphere.

Microscreen radiation shield for thermoelectric generator

DOEpatents

Hunt, Thomas K.; Novak, Robert F.; McBride, James R.

1990-01-01

The present invention provides a microscreen radiation shield which reduces radiative heat losses in thermoelectric generators such as sodium heat engines without reducing the efficiency of operation of such devices. The radiation shield is adapted to be interposed between a reaction zone and a means for condensing an alkali metal vapor in a thermoelectric generator for converting heat energy directly to electrical energy. The radiation shield acts to reflect infrared radiation emanating from the reaction zone back toward the reaction zone while permitting the passage of the alkali metal vapor to the condensing means. The radiation shield includes a woven wire mesh screen or a metal foil having a plurality of orifices formed therein. The orifices in the foil and the spacing between the wires in the mesh is such that radiant heat is reflected back toward the reaction zone in the interior of the generator, while the much smaller diameter alkali metal atoms such as sodium pass directly through the orifices or along the metal surfaces of the shield and through the orifices with little or no impedance.

Cost-efficiency trade-off and the design of thermoelectric power generators.

PubMed

Yazawa, Kazuaki; Shakouri, Ali

2011-09-01

The energy conversion efficiency of today's thermoelectric generators is significantly lower than that of conventional mechanical engines. Almost all of the existing research is focused on materials to improve the conversion efficiency. Here we propose a general framework to study the cost-efficiency trade-off for thermoelectric power generation. A key factor is the optimization of thermoelectric modules together with their heat source and heat sinks. Full electrical and thermal co-optimization yield a simple analytical expression for optimum design. Based on this model, power output per unit mass can be maximized. We show that the fractional area coverage of thermoelectric elements in a module could play a significant role in reducing the cost of power generation systems.

Solar Thermoelectricity via Advanced Latent Heat Storage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Olsen, Michele L.; Rea, J.; Glatzmaier, Greg C.

2016-05-31

We report on a new modular, dispatchable, and cost-effective solar electricity-generating technology. Solar ThermoElectricity via Advanced Latent heat Storage (STEALS) integrates several state-of-the-art technologies to provide electricity on demand. In the envisioned STEALS system, concentrated sunlight is converted to heat at a solar absorber. The heat is then delivered to either a thermoelectric (TE) module for direct electricity generation, or to charge a phase change material for thermal energy storage, enabling subsequent generation during off-sun hours, or both for simultaneous electricity production and energy storage. The key to making STEALS a dispatchable technology lies in the development of a 'thermalmore » valve,' which controls when heat is allowed to flow through the TE module, thus controlling when electricity is generated. The current project addresses each of the three major subcomponents, (i) the TE module, (ii) the thermal energy storage system, and (iii) the thermal valve. The project also includes system-level and techno- economic modeling of the envisioned integrated system and will culminate in the demonstration of a laboratory-scale STEALS prototype capable of generating 3kWe.« less

Solar thermoelectricity via advanced latent heat storage

NASA Astrophysics Data System (ADS)

Olsen, M. L.; Rea, J.; Glatzmaier, G. C.; Hardin, C.; Oshman, C.; Vaughn, J.; Roark, T.; Raade, J. W.; Bradshaw, R. W.; Sharp, J.; Avery, A. D.; Bobela, D.; Bonner, R.; Weigand, R.; Campo, D.; Parilla, P. A.; Siegel, N. P.; Toberer, E. S.; Ginley, D. S.

2016-05-01

We report on a new modular, dispatchable, and cost-effective solar electricity-generating technology. Solar ThermoElectricity via Advanced Latent heat Storage (STEALS) integrates several state-of-the-art technologies to provide electricity on demand. In the envisioned STEALS system, concentrated sunlight is converted to heat at a solar absorber. The heat is then delivered to either a thermoelectric (TE) module for direct electricity generation, or to charge a phase change material for thermal energy storage, enabling subsequent generation during off-sun hours, or both for simultaneous electricity production and energy storage. The key to making STEALS a dispatchable technology lies in the development of a "thermal valve," which controls when heat is allowed to flow through the TE module, thus controlling when electricity is generated. The current project addresses each of the three major subcomponents, (i) the TE module, (ii) the thermal energy storage system, and (iii) the thermal valve. The project also includes system-level and techno- economic modeling of the envisioned integrated system and will culminate in the demonstration of a laboratory-scale STEALS prototype capable of generating 3kWe.

Simulation, design and fabrication of a planar micro thermoelectric generator

NASA Astrophysics Data System (ADS)

Pelegrini, S.; Adami, A.; Collini, C.; Conci, P.; Lorenzelli, L.; Pasa, A. A.

2013-05-01

This study describes the design, simulation, and micro fabrication of a micro thermoelectric generator (μTEG) based on planar technology using constantan (CuNi) and copper (Cu) thermocouples deposited electrochemically (ECD) on silicon substrate. The present thin film technology can be manufactured into large area and also on flexible substrate with low cost of production and can be used to exploit waste heat from equipments or hot surfaces in general. In the current implementation, the silicon structure has been designed and optimized with analytical models and FE simulations in order to exploit the different thermal conductivity of silicon and air gaps to produce the maximum temperature difference on a planar surface. The results showed that a temperature difference of 10K across the structure creates a temperature difference of 5.3K on the thermocouples, thus providing an efficiency of thermal distribution up to 55%, depending on the heat convection at the surface. Efficiency of module has been experimentally tested under different working condition, showing the dependence of module output on the external heat exchange (natural and forced convection). Maximum generated potential at 6m/s airflow is 5.7V/m2 K and thermoelectric efficiency is 1.9μW K-2 m-2.

Design, fabrication, and testing of energy-harvesting thermoelectric generator

NASA Astrophysics Data System (ADS)

Jovanovic, Velimir; Ghamaty, Saeid

2006-03-01

An energy-harvesting thermoelectric generator (TEG) is being developed to provide power for wireless sensors used in health monitoring of Navy machinery. TEGs are solid-state devices that convert heat directly into electricity without any moving parts. In this application, the TEGs utilize the heat transfer between shipboard waste heat sources and the ambient air to generate electricity. In order to satisfy the required small design volume of less than one cubic inch, Hi-Z is using its innovative thin-film Quantum Well (QW) thermoelectric technology that will provide a factor of four increase in efficiency and a large reduction in the device volume over the currently used bulk Bi IITe 3 based thermoelectics. QWs are nanostructured multi-layer films. These wireless sensors can be used to detect cracks, corrosion, impact damage, and temperature and vibration excursions as part of the Condition Based Maintenance (CBM) of the Navy ship machinery. The CBM of the ship machinery can be significantly improved by automating the process with the use of self-powered wireless sensors. These power-harvesting TEGs can be used to replace batteries as electrical power sources and to eliminate power cables and data lines. The first QW TEG module was fabricated and initial tests were successful. It is planned to conduct performance tests the entire prototype QW TEG device (consisting of the TEG module, housing, thermal insulation and the heat sink) in a simulated thermal environment of a Navy ship.

Recent advances in 2D thermoelectric materials

NASA Astrophysics Data System (ADS)

Yu, Jiabing; Sun, Qiang; Jena, Puru

2016-12-01

The waste heat generated by car engines, power plants, home furnaces and other fossil fuel-burning machinery play an adverse role in the climate. Development of efficient, light-weight, cost-effective, and environmentally-benign thermoelectric materials can help in converting wasted heat into useable energy, thus helping the environment. In this brief review we discuss theoretical methods that can complement experimental search for efficient thermoelectric materials. Using Boltzmann transport theory with a constant relaxation time approximation and non-equilibrium Green's function approach we study thermoelectric parameters by focusing on two dimensional materials ranging from graphene and graphdiyne to phosphorene, transition metal dichalogenides and metal carbides. In some circumstances, the reduced dimension is found to increase the Seebeck coefficient and decrease the thermal conductivity, necessary for improving thermoelectric conversion performance. We also suggest some future studies in this topic.

Complex thermoelectric materials.

PubMed

Snyder, G Jeffrey; Toberer, Eric S

2008-02-01

Thermoelectric materials, which can generate electricity from waste heat or be used as solid-state Peltier coolers, could play an important role in a global sustainable energy solution. Such a development is contingent on identifying materials with higher thermoelectric efficiency than available at present, which is a challenge owing to the conflicting combination of material traits that are required. Nevertheless, because of modern synthesis and characterization techniques, particularly for nanoscale materials, a new era of complex thermoelectric materials is approaching. We review recent advances in the field, highlighting the strategies used to improve the thermopower and reduce the thermal conductivity.

Compatibility of Segments of Thermoelectric Generators

NASA Technical Reports Server (NTRS)

Snyder, G. Jeffrey; Ursell, Tristan

2009-01-01

electric current and heat-conduction power and leads to the concept of compatibility factor (s) for a given thermoelectric material, defined as the value of u that maximizes the reduced efficiency of the aforementioned model thermoelectric generator.

Fuel Economy Improvement by Utilizing Thermoelectric Generator in Heavy-Duty Vehicle

NASA Astrophysics Data System (ADS)

Deng, Y. D.; Hu, T.; Su, C. Q.; Yuan, X. H.

2017-05-01

Recent advances in thermoelectric technology have made exhaust-based thermoelectric generators (TEGs) promising for recovery of waste heat. Utilization of exhaust-based TEGs in heavy-duty vehicles was studied in this work. Given that the generated power is limited, the alternator is still indispensable. To improve the fuel economy, the generated electricity must be integrated into the automotive electrical system and consumed by electrical loads. Therefore, two feasible ways of integrating the generated electricity into the automotive electrical system are discussed: one in which the original alternator works only under certain conditions, i.e., the "thermostat" strategy, and another in which a smaller alternator is adopted and works together with the TEG, i.e., the "cooperative work" strategy. The overall performance and efficiency are obtained through simulation analysis. The simulation results show that both methods can improve the fuel economy, but the former provides better results. Moreover, if the electrical loads can be properly modified, the fuel economy is further improved. These simulation results lay a solid foundation for application of TEGs in vehicles in the future.

Thermoelectric generator having a resiliently mounted removable thermoelectric module

DOEpatents

Purdy, David L.; Shapiro, Zalman M.; Hursen, Thomas F.; Maurer, Gerould W.

1976-11-02

An electrical generator having an Isotopic Heat Capsule including radioactive fuel rod 21 as a primary heat source and Thermoelectric Modules 41 and 43 as converters. The Biological Shield for the Capsule is suspended from Spiders at each end each consisting of pretensioned rods 237 and 239 defining planes at right angles to each other. The Modules are mounted in cups 171 of transition members 173 of a heat rejection Fin Assembly whose fins 195 and 197 extend from both sides of the transition member 173 for effective cooling.

Integration of Research for an Exhaust Thermoelectric Generator and the Outer Flow Field of a Car

NASA Astrophysics Data System (ADS)

Jiang, T.; Su, C. Q.; Deng, Y. D.; Wang, Y. P.

2017-05-01

The exhaust thermoelectric generator (TEG) can generate electric power from a car engine's waste heat. It is important to maintain a sufficient temperature difference across the thermoelectric modules. The radiator is connected to the cooling units of the thermoelectric modules and used to take away the heat from the TEG system. This paper focuses on the research for the integration of a TEG radiator and the flow field of the car chassis, aiming to cool the radiator by the high speed flow around the chassis. What is more, the TEG radiator is designed as a spoiler to optimize the flow field around the car chassis and even reduce the aerodynamic drag. Concentrating on the flow pressure of the radiator and the aerodynamic drag force, a sedan model with eight different schemes of radiator configurations are studied by computational fluid dynamics simulation. Finally, the simulation results indicate that a reasonable radiator configuration can not only generate high flow pressure to improve the cooling performance, which provides a better support for the TEG system, but also acts as a spoiler to reduce the aerodynamic drag force.

Numerical Investigation for Strengthening Heat Transfer Mechanism of the Tube-Row Heat Exchanger in a Compact Thermoelectric Generator

NASA Astrophysics Data System (ADS)

Zhang, Zheng; Chen, Zijian; Liu, Hongwu; Yue, Hao; Chen, Dongbo; Qin, Delei

2018-04-01

According to the basic principle of heat transfer enhancement, a 1-kW compact thermoelectric generator (TEG) is proposed that is suitable for use at high temperatures and high flow speeds. The associated heat exchanger has a tube-row structure with a guide-plate to control the thermal current. The heat exchanger has a volume of 7 L, and the TEG has a mass of 8 kg (excluding the thermoelectric modules (TEMs)). In this paper, the heat transfer process of the tube-row exchanger is modeled and analyzed numerically; and the influences of its structure on the heat transfer and temperature status of the TEMs are investigated. The results show that use of the thin - wall pipes and increase of surface roughness inside the pipes are effective ways to improve the heat transfer efficiency, obtain the rated surface temperature, and make the TEG compact and lightweight. Furthermore, under the same conditions, the calculated results are compared with the data of a fin heat exchanger. The comparison results show that the volume and mass of the tube-row heat exchanger are 19% and 33% lower than those of the fin type unit, and that the pressure drop is reduced by 16%. In addition, the average temperature in the tube-row heat exchanger is increased by 15°C and the average temperature difference is increased by 19°C; the tube-row TEG has a more compact volume and better temperature characteristics.

Numerical Investigation for Strengthening Heat Transfer Mechanism of the Tube-Row Heat Exchanger in a Compact Thermoelectric Generator

NASA Astrophysics Data System (ADS)

Zhang, Zheng; Chen, Zijian; Liu, Hongwu; Yue, Hao; Chen, Dongbo; Qin, Delei

2018-06-01

According to the basic principle of heat transfer enhancement, a 1-kW compact thermoelectric generator (TEG) is proposed that is suitable for use at high temperatures and high flow speeds. The associated heat exchanger has a tube-row structure with a guide-plate to control the thermal current. The heat exchanger has a volume of 7 L, and the TEG has a mass of 8 kg (excluding the thermoelectric modules (TEMs)). In this paper, the heat transfer process of the tube-row exchanger is modeled and analyzed numerically; and the influences of its structure on the heat transfer and temperature status of the TEMs are investigated. The results show that use of the thin - wall pipes and increase of surface roughness inside the pipes are effective ways to improve the heat transfer efficiency, obtain the rated surface temperature, and make the TEG compact and lightweight. Furthermore, under the same conditions, the calculated results are compared with the data of a fin heat exchanger. The comparison results show that the volume and mass of the tube-row heat exchanger are 19% and 33% lower than those of the fin type unit, and that the pressure drop is reduced by 16%. In addition, the average temperature in the tube-row heat exchanger is increased by 15°C and the average temperature difference is increased by 19°C; the tube-row TEG has a more compact volume and better temperature characteristics.

Synthesis, Transport, and Thermoelectric Studies of Topological Dirac Semimetal Cd3As2 for Room Temperature Waste Heat Recovery and Energy Conversion

NASA Astrophysics Data System (ADS)

Hosseini, Tahereh A.

Rising rates of the energy consumption and growing concerns over the climate change worldwide have made energy efficiency an urgent problem to address. Nowadays, almost two-thirds of the energy produced by burning fossil fuels to generate electrical power is lost in the form of the heat. On this front, increasing electrical power generation through a waste heat recovery remains one of the highly promising venues of the energy research. Thermo-electric generators (TEGs) directly convert thermal energy into electrical and are the prime candidates for application in low-grade thermal energy/ waste heat recovery. The key commercial TE materials, e.g. PbTe and Bi2Te 3, have room temperature ZT of less than 1, whereas ZT exceeding 3 is required for a TEG to be economically viable. With the thermoelectric efficiency typically within a few percent range and a low efficiency-to-cost ratio of TEGs, there has been a resurgence in the search for new class of thermo-electric materials for developing high efficiency thermo-to-electric energy conversion systems, with phonon-glass electron-crystal materials holding the most promise. Herein, we focus on synthesis, characterization and investigation of electrical, thermo-electrical and thermal characteristics of crystalline Cd 3As2, a high performance 3D topological Dirac semimetal with Dirac fermions dispersing linearly in k3-space and possessing one of the largest electron mobilities known for crystalline materials, i.e. 104-105cm2V-1 s-1. Suppression of carrier backscattering, ultra-high charge carrier mobility, and inherently low thermal conductivity make this semimetal a key candidate for demonstrating high, device-favorable S and in turn ZT. In this work, a low-temperature vapor-based crystallization pathway was developed and optimized to produce free standing 2D cm-size crystals in Cd 3As2. Compared to the bulk crystals produced in previous studies, e.g. Piper-Polich, Bridgman, or flux method, Cd3As 2 samples were synthesized

A Novel Electro Conductive Graphene/Silicon-Dioxide Thermo-Electric Generator

NASA Astrophysics Data System (ADS)

Rahman, Ataur; Abdi, Yusuf

2017-03-01

Thermoelectric generators are all solid-state devices that convert heat energy into electrical energy. The total energy (fuel) supplied to the engine, approximately 30 to 40% is converted into useful mechanical work; whereas the remaining is expelled to the environment as heat through exhaust gases and cooling systems, resulting in serious green house gas (GHG) emission. By converting waste energy into electrical energy is the aim of this manuscript. The technologies reported on waste heat recovery from exhaust gas of internal combustion engines (ICE) are thermo electric generators (TEG) with finned type, Rankine cycle (RC) and Turbocharger. This paper has presented an electro-conductive graphene oxide/silicon-dioxide (GO-SiO2) composite sandwiched by phosphorus (P) and boron (B) doped silicon (Si) TEG to generate electricity from the IC engine exhaust heat. Air-cooling and liquid cooling techniques adopted conventional TEG module has been tested individually for the electricity generation from IC engine exhausts heat at engine speed of 1000-3000rpm. For the engine speed of 7000 rpm, the maximum voltage was recorded as 1.12V and 4.00V for the air-cooling and liquid cooling respectively. The GO-SiO2 simulated result shows that it’s electrical energy generation is about 80% more than conventional TEG for the exhaust temperature of 500°C. The GO-SiO2 composite TEG develops 524W to 1600W at engine speed 1000 to 5000 rpm, which could contribute to reduce the 10-12% of engine total fuel consumption and improve emission level by 20%.

Efficiency Study of a Commercial Thermoelectric Power Generator (TEG) Under Thermal Cycling

NASA Astrophysics Data System (ADS)

Hatzikraniotis, E.; Zorbas, K. T.; Samaras, I.; Kyratsi, Th.; Paraskevopoulos, K. M.

2010-09-01

Thermoelectric generators (TEGs) make use of the Seebeck effect in semiconductors for the direct conversion of heat to electrical energy. The possible use of a device consisting of numerous TEG modules for waste heat recovery from an internal combustion (IC) engine could considerably help worldwide efforts towards energy saving. However, commercially available TEGs operate at temperatures much lower than the actual operating temperature range in the exhaust pipe of an automobile, which could cause structural failure of the thermoelectric elements. Furthermore, continuous thermal cycling could lead to reduced efficiency and lifetime of the TEG. In this work we investigate the long-term performance and stability of a commercially available TEG under temperature and power cycling. The module was subjected to sequential hot-side heating (at 200°C) and cooling for long times (3000 h) in order to measure changes in the TEG’s performance. A reduction in Seebeck coefficient and an increase in resistivity were observed. Alternating-current (AC) impedance measurements and scanning electron microscope (SEM) observations were performed on the module, and results are presented and discussed.

Thin Thermoelectric Generator System for Body Energy Harvesting

NASA Astrophysics Data System (ADS)

Settaluri, Krishna T.; Lo, Hsinyi; Ram, Rajeev J.

2012-06-01

Wearable thermoelectric generators (TEGs) harvest thermal energy generated by the body to generate useful electricity. The performance of these systems is limited by (1) the small working temperature differential between the body and ambient, (2) the desire to use natural air convection cooling on the cold side of the generator, and (3) the requirement for thin, lightweight systems that are comfortable for long-term use. Our work has focused on the design of the heat transfer system as part of the overall thermoelectric (TE) system. In particular, the small heat transfer coefficient for natural air convection results in a module thermal impedance that is smaller than that of the heat sink. In this heat-sink-limited regime, the thermal resistance of the generator should be optimized to match that of the heat sink to achieve the best performance. In addition, we have designed flat (1 mm thickness) copper heat spreaders to realize performance surpassing splayed pin heat sinks. Two-dimensional (2-D) heat spreading exploits the large surface area available in a wristband and allows patterned copper to efficiently cool the TE. A direct current (DC)/DC converter is integrated on the wristband. The system generates up to 28.5 μW/cm2 before the converter and 8.6 μW/cm2 after the converter, with 30% efficiency. It generates output of 4.15 V with overall thickness under 5 mm.

Thermoelectric-Driven Autonomous Sensors for a Biomass Power Plant

NASA Astrophysics Data System (ADS)

Rodríguez, A.; Astrain, D.; Martínez, A.; Gubía, E.; Sorbet, F. J.

2013-07-01

This work presents the design and development of a thermoelectric generator intended to harness waste heat in a biomass power plant, and generate electric power to operate sensors and the required electronics for wireless communication. The first objective of the work is to design the optimum thermoelectric generator to harness heat from a hot surface, and generate electric power to operate a flowmeter and a wireless transmitter. The process is conducted by using a computational model, presented in previous papers, to determine the final design that meets the requirements of electric power consumption and number of transmissions per minute. Finally, the thermoelectric generator is simulated to evaluate its performance. The final device transmits information every 5 s. Moreover, it is completely autonomous and can be easily installed, since no electric wires are required.

Numerical Investigation on the Performance of an Automotive Thermoelectric Generator with Exhaust-Module-Coolant Direct Contact

NASA Astrophysics Data System (ADS)

Wang, Yiping; Tang, Yulin; Deng, Yadong; Su, Chuqi

2017-12-01

Energy conservation and environmental protection have typically been a concern of research. Researchers have confirmed that in automotive engines, just 12-25% of the fuel energy converts into effective work and 30-40% gets wasted in the form of exhaust. Saidur et al. (Energy Policy 37:3650, 2009) and Hasanuzzaman et al. (Energy 36:233, 2011). It will be significant to enhance fuel availability and decrease environmental pollution if the waste heat in the exhaust could be recovered. Thermoelectric generators (TEGs), which can translate heat into electricity, have become a topic of interest for vehicle exhaust waste heat recovery. In conventional automotive TEGs, the thermoelectric modules (TEMs) are arranged between the exhaust tank and the coolant tank. The TEMs do not contact the hot exhaust and coolant, which leads to low heat transfer efficiency. Moreover, to provide enough packing force to keep good contact with the exhaust tank and the coolant tank, the framework required is so robust that the TEGs become too heavy. Therefore, in current study, an automotive TEG was designed which included one exhaust channel, one coolant channel and several TEMs. In the TEG, the TEMs which contacted the exhaust and coolant directly were inserted into the walls of each coolant channel. To evaluate the performance of the automotive TEG, the flow field and temperature field were computed by computational fluid dynamics (CFD). Based on the temperature distribution obtained by CFD and the performance parameters of the modules, the total power generation was obtained by some proved empirical formulas. Compared with conventional automotive TEGs, the power generation per unit volume exhaust was boosted.

Numerical Investigation on the Performance of an Automotive Thermoelectric Generator with Exhaust-Module-Coolant Direct Contact

NASA Astrophysics Data System (ADS)

Wang, Yiping; Tang, Yulin; Deng, Yadong; Su, Chuqi

2018-06-01

Energy conservation and environmental protection have typically been a concern of research. Researchers have confirmed that in automotive engines, just 12-25% of the fuel energy converts into effective work and 30-40% gets wasted in the form of exhaust. Saidur et al. (Energy Policy 37:3650, 2009) and Hasanuzzaman et al. (Energy 36:233, 2011). It will be significant to enhance fuel availability and decrease environmental pollution if the waste heat in the exhaust could be recovered. Thermoelectric generators (TEGs), which can translate heat into electricity, have become a topic of interest for vehicle exhaust waste heat recovery. In conventional automotive TEGs, the thermoelectric modules (TEMs) are arranged between the exhaust tank and the coolant tank. The TEMs do not contact the hot exhaust and coolant, which leads to low heat transfer efficiency. Moreover, to provide enough packing force to keep good contact with the exhaust tank and the coolant tank, the framework required is so robust that the TEGs become too heavy. Therefore, in current study, an automotive TEG was designed which included one exhaust channel, one coolant channel and several TEMs. In the TEG, the TEMs which contacted the exhaust and coolant directly were inserted into the walls of each coolant channel. To evaluate the performance of the automotive TEG, the flow field and temperature field were computed by computational fluid dynamics (CFD). Based on the temperature distribution obtained by CFD and the performance parameters of the modules, the total power generation was obtained by some proved empirical formulas. Compared with conventional automotive TEGs, the power generation per unit volume exhaust was boosted.

Three-Dimensional Finite-Element Simulation for a Thermoelectric Generator Module

NASA Astrophysics Data System (ADS)

Hu, Xiaokai; Takazawa, Hiroyuki; Nagase, Kazuo; Ohta, Michihiro; Yamamoto, Atsushi

2015-10-01

A three-dimensional closed-circuit numerical model of a thermoelectric generator (TEG) module has been constructed with COMSOL® Multiphysics to verify a module test system. The Seebeck, Peltier, and Thomson effects and Joule heating are included in the thermoelectric conversion model. The TEG model is employed to simulate the operation of a 16-leg TEG module based on bismuth telluride with temperature-dependent material properties. The module is mounted on a test platform, and simulated by combining the heat conduction process and thermoelectric conversion process. Simulation results are obtained for the terminal voltage, output power, heat flow, and efficiency as functions of the electric current; the results are compared with measurement data. The Joule and Thomson heats in all the thermoelectric legs, as functions of the electric current, are calculated by finite-element volume integration over the entire legs. The Peltier heat being pumped at the hot side and released at the cold side of the module are also presented in relation to the electric current. The energy balance relations between heat and electricity are verified to support the simulation.

Modeling of various heat adapter plate 4 and 6 array for optimization of thermoelectric generator element using modified diffusion equation

NASA Astrophysics Data System (ADS)

Defrianto; Tambunan, W.; Lazuardi

2017-07-01

The use of waste heat from exhaust gas and converting it to electricity is now an alternative to harvest a cheap and clean energy. Thermoelectric generator (TEG) has the ability to directly recover such waste heat and generate electricity. The aim of this study is to simulate the heat transfer on the aluminum adapter plate for homogeneity temperature distribution coupled with hot side of TEG type 40-40-10/100 from Firma Eureka and adjust their high temperatures to the TEG operating temperature to avoid the element damage. Modelling was carried out using MATLAB modified diffusion equation with Dirichlet boundary conditions at defined temperature which has been set at the ends of the heat source at 463K and 373K ± 10% on the hot side of the TEG element. The use of nylon insulated material is modeled after Neumann boundary condition in which the temperature gradient is ∂T/∂n = 0 out of boundary. Realization of the modelling is done by designing a heat conductive plate using software ACAD 2015 and converted into a binary file format of Mathlab to form a finite element mesh with geometry variations of solid model. The solid cubic model of aluminum adapter plate has a dimension of 40mm length, 40mm width and also 20mm, 30mm and 40mm thickness arranged in two arrays of 2×2 and 2×3 of TEG elements. Results showed a temperature decrease about 40.95% and 50.02% respectively from the initial source and appropriate with TEG temperature tolerance.

Bifunctional thermoelectric tube made of tilted multilayer material as an alternative to standard heat exchangers.

PubMed

Takahashi, Kouhei; Kanno, Tsutomu; Sakai, Akihiro; Tamaki, Hiromasa; Kusada, Hideo; Yamada, Yuka

2013-01-01

Enormously large amount of heat produced by human activities is now mostly wasted into the environment without use. To realize a sustainable society, it is important to develop practical solutions for waste heat recovery. Here, we demonstrate that a tubular thermoelectric device made of tilted multilayer of Bi(0.5)Sb(1.5)Te3/Ni provides a promising solution. The Bi(0.5)Sb(1.5)Te3/Ni tube allows tightly sealed fluid flow inside itself, and operates in analogy with the standard shell and tube heat exchanger. We show that it achieves perfect balance between efficient heat exchange and high-power generation with a heat transfer coefficient of 4.0 kW/m(2)K and a volume power density of 10 kW/m(3) using low-grade heat sources below 100°C. The Bi(0.5)Sb(1.5)Te3/Ni tube thus serves as a power generator and a heat exchanger within a single unit, which is advantageous for developing new cogeneration systems in factories, vessels, and automobiles where cooling of excess heat is routinely carried out.

Bifunctional thermoelectric tube made of tilted multilayer material as an alternative to standard heat exchangers

PubMed Central

Takahashi, Kouhei; Kanno, Tsutomu; Sakai, Akihiro; Tamaki, Hiromasa; Kusada, Hideo; Yamada, Yuka

2013-01-01

Enormously large amount of heat produced by human activities is now mostly wasted into the environment without use. To realize a sustainable society, it is important to develop practical solutions for waste heat recovery. Here, we demonstrate that a tubular thermoelectric device made of tilted multilayer of Bi0.5Sb1.5Te3/Ni provides a promising solution. The Bi0.5Sb1.5Te3/Ni tube allows tightly sealed fluid flow inside itself, and operates in analogy with the standard shell and tube heat exchanger. We show that it achieves perfect balance between efficient heat exchange and high-power generation with a heat transfer coefficient of 4.0 kW/m2K and a volume power density of 10 kW/m3 using low-grade heat sources below 100°C. The Bi0.5Sb1.5Te3/Ni tube thus serves as a power generator and a heat exchanger within a single unit, which is advantageous for developing new cogeneration systems in factories, vessels, and automobiles where cooling of excess heat is routinely carried out. PMID:23511347

3D printing of shape-conformable thermoelectric materials using all-inorganic Bi2Te3-based inks

NASA Astrophysics Data System (ADS)

Kim, Fredrick; Kwon, Beomjin; Eom, Youngho; Lee, Ji Eun; Park, Sangmin; Jo, Seungki; Park, Sung Hoon; Kim, Bong-Seo; Im, Hye Jin; Lee, Min Ho; Min, Tae Sik; Kim, Kyung Tae; Chae, Han Gi; King, William P.; Son, Jae Sung

2018-04-01

Thermoelectric energy conversion offers a unique solution for generating electricity from waste heat. However, despite recent improvements in the efficiency of thermoelectric materials, the widespread application of thermoelectric generators has been hampered by challenges in fabricating thermoelectric materials with appropriate dimensions to perfectly fit heat sources. Herein, we report an extrusion-based three-dimensional printing method to produce thermoelectric materials with geometries suitable for heat sources. All-inorganic viscoelastic inks were synthesized using Sb2Te3 chalcogenidometallate ions as inorganic binders for Bi2Te3-based particles. Three-dimensional printed materials with various geometries showed homogenous thermoelectric properties, and their dimensionless figure-of-merit values of 0.9 (p-type) and 0.6 (n-type) were comparable to the bulk values. Conformal cylindrical thermoelectric generators made of 3D-printed half rings mounted on an alumina pipe were studied both experimentally and computationally. Simulations show that the power output of the conformal, shape-optimized generator is higher than that of conventional planar generators.

Utilization of Aluminum Waste with Hydrogen and Heat Generation

NASA Astrophysics Data System (ADS)

Buryakovskaya, O. A.; Meshkov, E. A.; Vlaskin, M. S.; Shkolnokov, E. I.; Zhuk, A. Z.

2017-10-01

A concept of energy generation via hydrogen and heat production from aluminum containing wastes is proposed. The hydrogen obtained by oxidation reaction between aluminum waste and aqueous solutions can be supplied to fuel cells and/or infrared heaters for electricity or heat generation in the region of waste recycling. The heat released during the reaction also can be effectively used. The proposed method of aluminum waste recycling may represent a promising and cost-effective solution in cases when waste transportation to recycling plants involves significant financial losses (e.g. remote areas). Experiments with mechanically dispersed aluminum cans demonstrated that the reaction rate in alkaline solution is high enough for practical use of the oxidation process. In theexperiments aluminum oxidation proceeds without any additional aluminum activation.

Applications of thermoelectric modules on heat flow detection.

PubMed

Leephakpreeda, Thananchai

2012-03-01

This paper presents quantitative analysis and practical scenarios of implementation of the thermoelectric module for heat flow detection. Mathematical models of the thermoelectric effects are derived to describe the heat flow from/to the detected media. It is observed that the amount of the heat flow through the thermoelectric module proportionally induces the conduction heat owing to the temperature difference between the hot side and the cold side of the thermoelectric module. In turn, the Seebeck effect takes place in the thermoelectric module where the temperature difference is converted to the electric voltage. Hence, the heat flow from/to the detected media can be observed from both the amount and the polarity of the voltage across the thermoelectric module. Two experiments are demonstrated for viability of the proposed technique by the measurements of the heat flux through the building wall and thermal radiation from the outdoor environment during daytime. Copyright © 2011 ISA. Published by Elsevier Ltd. All rights reserved.

Performance of a Thermoelectric Device with Integrated Heat Exchangers

NASA Astrophysics Data System (ADS)

Barry, Matthew M.; Agbim, Kenechi A.; Chyu, Minking K.

2015-06-01

Thermoelectric devices (TEDs) convert heat directly into electrical energy, making them well suited for waste heat recovery applications. An integrated thermoelectric device (iTED) is a restructured TED that allows more heat to enter the p-n junctions, thus producing a greater power output . An iTED has heat exchangers incorporated into the hot-side interconnectors with flow channels directing the working fluid through the heat exchangers. The iTED was constructed of p- and n-type bismuth-telluride semiconductors and copper interconnectors and rectangular heat exchangers. The performance of the iTED in terms of , produced voltage and current , heat input and conversion efficiency for various flow rates (), inlet temperatures (C) ) and load resistances () with a constant cold-side temperature ( = 0C) was conducted experimentally. An increase in had a greater effect on the performance than did an increase in . A 3-fold increase in resulted in a 3.2-, 3.1-, 9.7-, 3.5- and 2.8-fold increase in and respectively. For a constant of 50C, a 3-fold increase in from 3300 to 9920 resulted in 1.6-, 1.6-, 2.6-, 1.5- and 1.9-fold increases in , , , and respectively.

Modeling a Thermoelectric HVAC System for Automobiles

NASA Astrophysics Data System (ADS)

Junior, C. S.; Strupp, N. C.; Lemke, N. C.; Koehler, J.

2009-07-01

In automobiles thermal energy is used at various energy scales. With regard to reduction of CO2 emissions, efficient generation of hot and cold temperatures and wise use of waste heat are of paramount importance for car manufacturers worldwide. Thermoelectrics could be a vital component in automobiles of the future. To evaluate the applicability of thermoelectric modules in automobiles, a Modelica model of a thermoelectric liquid-gas heat exchanger was developed for transient simulations. The model uses component models from the object-oriented Modelica library TIL. It was validated based on experimental data of a prototype heat exchanger and used to simulate transient and steady-state behavior. The use of the model within the energy management of an automobile is successfully shown for the air-conditioning system of a car.

Research on a power management system for thermoelectric generators to drive wireless sensors on a spindle unit.

PubMed

Li, Sheng; Yao, Xinhua; Fu, Jianzhong

2014-07-16

Thermoelectric energy harvesting is emerging as a promising alternative energy source to drive wireless sensors in mechanical systems. Typically, the waste heat from spindle units in machine tools creates potential for thermoelectric generation. However, the problem of low and fluctuant ambient temperature differences in spindle units limits the application of thermoelectric generation to drive a wireless sensor. This study is devoted to presenting a transformer-based power management system and its associated control strategy to make the wireless sensor work stably at different speeds of the spindle. The charging/discharging time of capacitors is optimized through this energy-harvesting strategy. A rotating spindle platform is set up to test the performance of the power management system at different speeds. The experimental results show that a longer sampling cycle time will increase the stability of the wireless sensor. The experiments also prove that utilizing the optimal time can make the power management system work more effectively compared with other systems using the same sample cycle.

Research on a Power Management System for Thermoelectric Generators to Drive Wireless Sensors on a Spindle Unit

PubMed Central

Li, Sheng; Yao, Xinhua; Fu, Jianzhong

2014-01-01

Thermoelectric energy harvesting is emerging as a promising alternative energy source to drive wireless sensors in mechanical systems. Typically, the waste heat from spindle units in machine tools creates potential for thermoelectric generation. However, the problem of low and fluctuant ambient temperature differences in spindle units limits the application of thermoelectric generation to drive a wireless sensor. This study is devoted to presenting a transformer-based power management system and its associated control strategy to make the wireless sensor work stably at different speeds of the spindle. The charging/discharging time of capacitors is optimized through this energy-harvesting strategy. A rotating spindle platform is set up to test the performance of the power management system at different speeds. The experimental results show that a longer sampling cycle time will increase the stability of the wireless sensor. The experiments also prove that utilizing the optimal time can make the power management system work more effectively compared with other systems using the same sample cycle. PMID:25033189

High Temperature Thermoelectric Materials for Waste Heat Regeneration

DTIC Science & Technology

2013-01-01

ADDRESS. 1. REPORT DATE (DD-MM-YYYY) January 2013 2. REPORT TYPE Final 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE High Temperature...National Aeronautics and Space Administration’s (NASA) deep space explorations, which use radioisotope thermoelectric generators (RTGs) to produce...their octahedral voids (shown in figure 10a) with large rare- earth atoms to reduce their lattice conductivity (20). Ions can also be inserted to

Experimental Study and Optimization of Thermoelectricity-Driven Autonomous Sensors for the Chimney of a Biomass Power Plant

NASA Astrophysics Data System (ADS)

Rodríguez, A.; Astrain, D.; Martínez, A.; Aranguren, P.

2014-06-01

In the work discussed in this paper a thermoelectric generator was developed to harness waste heat from the exhaust gas of a boiler in a biomass power plant and thus generate electric power to operate a flowmeter installed in the chimney, to make it autonomous. The main objective was to conduct an experimental study to optimize a previous design obtained after computational work based on a simulation model for thermoelectric generators. First, several places inside and outside the chimney were considered as sites for the thermoelectricity-driven autonomous sensor. Second, the thermoelectric generator was built and tested to assess the effect of the cold-side heat exchanger on the electric power, power consumption by the flowmeter, and transmission frequency. These tests provided the best configuration for the heat exchanger, which met the transmission requirements for different working conditions. The final design is able to transmit every second and requires neither batteries nor electric wires. It is a promising application in the field of thermoelectric generation.

On the Use of Thermoelectric (TE) Applications Based on Commercial Modules: The Case of TE Generator and TE Cooler

NASA Astrophysics Data System (ADS)

Zorbas, K.; Hatzikraniotis, E.; Paraskevopoulos, K. M.; Kyratsi, Th.

2010-01-01

In recent years, thermoelectricity sees rapidly increasing usages in applications like portable refrigerators, beverage coolers, electronic component coolers etc. when used as Thermoelectric Cooler (TEC), and Thermoelectric Generators (TEG) which make use of the Seebeck effect in semiconductors for the direct conversion of heat into electrical energy and is of particular interest for systems of highest reliability or for waste heat recovery. In this work, we examine the performance of commercially available TEC and TEG. A prototype TEC-refrigerator has been designed, modeled and constructed for in-car applications. Additionally, a TEG was made, in order to measure the gained power and efficiency. Furthermore, a TEG module was tested on a small size car (Toyota Starlet, 1300 cc), in order to measure the gained power and efficiency for various engine loads. With the use of a modeling approach, we evaluated the thermal contact resistances and their influence on the final device efficiency.

Increasing the Efficiency of a Thermoelectric Generator Using an Evaporative Cooling System

NASA Astrophysics Data System (ADS)

Boonyasri, M.; Jamradloedluk, J.; Lertsatitthanakorn, C.; Therdyothin, A.; Soponronnarit, S.

2017-05-01

A system for reducing heat from the cold side of a thermoelectric (TE) power generator, based on the principle of evaporative cooling, is presented. An evaporative cooling system could increase the conversion efficiency of a TE generator. To this end, two sets of TE generators were constructed. Both TE generators were composed of five TE power modules. The cold and hot sides of the TE modules were fixed to rectangular fin heat sinks. The hot side heat sinks were inserted in a hot gas duct. The cold side of one set was cooled by the cooling air from a counter flow evaporative cooling system, whereas the other set was cooled by the parallel flow evaporative cooling system. The counter flow pattern had better performance than the parallel flow pattern. A comparison between the TE generator with and without an evaporative cooling system was made. Experimental results show that the power output increased by using the evaporative cooling system. This can significantly increase the TE conversion efficiency. The evaporative cooling system increased the power output of the TE generator from 22.9 W of ambient air flowing through the heat sinks to 28.6 W at the hot gas temperature of 350°C (an increase of about 24.8%). The present study shows the promising potential of using TE generators with evaporative cooling for waste heat recovery.

Radioisotope Thermoelectric Generators Emplaced in the Deep Ocean, Recover or Dispose in Situ

DTIC Science & Technology

1986-03-01

00 0 M! Technical Report 1106 Cll ) March 1986 Radioisotope Thermoelectric 00 Generators Emplaced in the Deep Ocean Recover or Dispose In Situ? 00...PROGRAM ELEMENT NO PROJECT NO8 TASK NO WORK UN IT NO NAV’COMPT 141 N� A8 WR00026 I I TITLE i,cmvd. Secunty CIaxssIoe,o’,) Radioisotope Thermoelectric ...disposal alternatives. . RTG DESCRIPTIONS Each RTG consists of a strontium-90 titanate heat source, thermoelectric generator, thermal insulation

Long term thermoelectric module testing system.

PubMed

D'Angelo, Jonathan; Hogan, Timothy

2009-10-01

Thermoelectric generators can be used for converting waste heat into electric power. Significant interest in developing new materials in recent years has led to the discovery of several promising thermoelectrics, however, there can be considerable challenges in developing the materials into working devices. Testing and feedback is needed at each step to gain valuable information for identification of difficulties, quality of the materials and modules, repeatability in fabrication, and longevity of the devices. This paper describes a long-term module testing system for monitoring the output power of a module over extended testing times. To evaluate the system, we have tested commercially available thermoelectric modules over a one month time period.

Development of High Power Density Micro-Thermoelectric Generators

NASA Astrophysics Data System (ADS)

Zhang, Wenhua

Thermoelectric generators (TEGs) are promising for the waste heat recovery in virtue of the ability to directly convert heat to electricity. Despite of their relatively low energy conversion efficiency, TEGs have many advantages including high reliability, long lifetime, and environmental friendliness. Especially, compared to conventional heat engines, TEGs are compact, scalable, and can be easily driven by small temperature differences. Potential applications of TEGs include thermal sensing, thermal management, and thermal energy harvesting to power wireless sensors and microelectronic devices such as wearable medical sensors and wristwatches. This dissertation presents my work on development of high power density non-flexible and flexible micro-TEGs for thermal energy harvesting in the ambient environment. Micro- TEGs are developed by a bottom-up approach combing electroplating and microfabrication processes. Pulsed electroplating is mainly adopted to deposit thermoelectric materials in the device fabrication. First, I collaborated with Dr. Zhou in our lab and systematically studied the effect of deposition parameters on composition, microstructure, and thermoelectric properties of the electroplated Bi2Te3 and Sb2 Te3 thin films. We demonstrated that thermoelectric properties of both Bi2Te3 and Sb2Te3 films can be enhanced by tuning the pulse off-to-on ratio. After the fundamental study on the deposition conditions, morphology, and thermoelectric properties of the electroplated materials, we fabricated a high power density cross-plane micro-TEG on the SiO2/Si substrate by integrating the pulsed electroplating with microfabrication processes. The TEG consists of a total of 127 pairs of n-type Bi2Te3 and ptype Sb2Te3 thermoelectric pillars embedded in a SU-8 matrix to enhance the overall mechanical strength of the device. Both bottom and top electrical connections are formed by electroplating, which is advantageous because of facile and low cost fabrication and low

Component for thermoelectric generator

DOEpatents

Purdy, David L.

1977-01-01

In a thermoelectric generator, a component comprises a ceramic insulator, having over limited areas thereof, each area corresponding to a terminal end of thermoelectric wires, a coating of a first metal which adheres to the insulator, and an electrical thermoelectric junction including a second metal which wets said first metal and adheres to said terminal ends but does not wet said insulator, and a cloth composed of electrically insulating threads interlaced with thermoelectric wires.

The Next Generation Thermoelectric Materials

NASA Astrophysics Data System (ADS)

Tritt, Terry M.

1999-11-01

Recently there been renewed interest in materials for thermoelectric refrigeration and power generation applications.^1, 2 Many new materials and new classes of materials are being investigated for potential thermoelectric applications. An introduction to thermoelectric refrigeration and power generation, the advantages and disadvantages and potential applications will be discussed. An overview of some of the current thermoelectric materials under investigation and the criteria for selection of new materials will be given. To be promising as a thermoelectric material, a material must have a high Seebeck coefficient, α, high electrical conductivity, σ, and a low thermal conductivity, λ. These parameters go into the material's dimensionless figure of merit ZT = α ^2σT/λ. Our research at Clemson is focused on a number of new materials, quasicrystals and pentatelluride materials, which show promise for thermoelectrics and these systems will be briefly discussed. Demonstrations of thermoelectric devices will be shown and discussed. 1.) Thermoelectric Materials: New Directions and Approaches, MRS Volumes 478 and 545, edited by Terry M. Tritt et. al. 2.) G. Mahan, B. Sales and J. Sharp, Physics Today, March 50, 42, 1997

Simulation Analysis of Tilted Polyhedron-Shaped Thermoelectric Elements

NASA Astrophysics Data System (ADS)

Meng, Xiangning; Suzuki, Ryosuke O.

2015-06-01

The generation of thermoelectricity is considered a promising approach to harness the waste heat generated in industries, automobiles, gas fields, and other man-made processes. The waste heat can be converted to electricity via a thermoelectric (TE) generator. In this light, the generator performance depends on the geometric configuration of its constituent elements as well as their material properties. Our previous work reported TE behaviors for modules consisting of parallelogram-shaped elements, because elements with tilted laminate structures provide increased mechanical stability and efficient heat-transferring ability from the hot surface to the cold surface. Here, we study TE elements in the shape of a polyhedron that is obtained by mechanically truncating the edges of a parallelogram element in order to further enhance the generator performance and reduce TE material usage. The TE performance of the modules consisting of these polyhedron elements is numerically simulated by using the finite-volume method. The output power, voltage, and current of the polyhedral TE module are greater than those of the parallelogram-element module. The polyhedron shape positively affects heat transfer and the flow of electric charges in the light of increasing the efficiency of conversion from heat to electricity. By varying the shape of the truncated portions, we determine the optimal shape that enables homogeneous heat flux distribution and slow diffusion of thermal energy to obtain the better efficiency of conversion of heat into electricity. We believe that the findings of our study can significantly contribute to the design policy in TE generation.

Microscreen radiation shield for thermoelectric generator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hunt, T.K.; Novak, R.F.; McBride, J.R.

1990-08-14

This patent describes a radiation shield adapted to be interposed between a reaction zone and a means for condensing an alkali metal vapor in a thermoelectric generator for converting heat energy directly to electrical energy. The radiation shield comprises woven wire mesh screen, the spacing between the wires forming the mesh screen being such that the radiation shield reflects thermal radiation while permitting the passage of alkali metal vapor therethrough.

High Performance Oxides-Based Thermoelectric Materials

NASA Astrophysics Data System (ADS)

Ren, Guangkun; Lan, Jinle; Zeng, Chengcheng; Liu, Yaochun; Zhan, Bin; Butt, Sajid; Lin, Yuan-Hua; Nan, Ce-Wen

2015-01-01

Thermoelectric materials have attracted much attention due to their applications in waste-heat recovery, power generation, and solid state cooling. In comparison with thermoelectric alloys, oxide semiconductors, which are thermally and chemically stable in air at high temperature, are regarded as the candidates for high-temperature thermoelectric applications. However, their figure-of-merit ZT value has remained low, around 0.1-0.4 for more than 20 years. The poor performance in oxides is ascribed to the low electrical conductivity and high thermal conductivity. Since the electrical transport properties in these thermoelectric oxides are strongly correlated, it is difficult to improve both the thermoelectric power and electrical conductivity simultaneously by conventional methods. This review summarizes recent progresses on high-performance oxide-based thermoelectric bulk-materials including n-type ZnO, SrTiO3, and In2O3, and p-type Ca3Co4O9, BiCuSeO, and NiO, enhanced by heavy-element doping, band engineering and nanostructuring.

Mg2BIV: Narrow Bandgap Thermoelectric Semiconductors

NASA Astrophysics Data System (ADS)

Kim, Il-Ho

2018-05-01

Thermoelectric materials can convert thermal energy directly into electric energy and vice versa. The electricity generation from waste heat via thermoelectric devices can be considered as a new energy source. For instance, automotive exhaust gas and all industrial processes generate an enormous amount of waste heat that can be converted to electricity by using thermoelectric devices. Magnesium compound Mg2BIV (BIV = Si, Ge or Sn) has a favorable combination of physical and chemical properties and can be a good base for the development of new efficient thermoelectrics. Because they possess similar properties to those of group BIV elemental semiconductors, they have been recognized as good candidates for thermoelectric applications. Mg2Si, Mg2Ge and Mg2Sn with an antifluorite structure are narrow bandgap semiconductors with indirect band gaps of 0.77 eV, 0.74 eV, and 0.35 eV, respectively. Mg2BIV has been recognized as a promising material for thermoelectric energy conversion at temperatures ranging from 500 K to 800 K. Compared to other thermoelectric materials operating in the similar temperature range, such as PbTe and filled skutterudites, the important aspects of Mg2BIV are non-toxic and earth-abundant elements. Based on classical thermoelectric theory, the material factor β ( m* / m e)3/2μκ L -1 can be utilized as the criterion for thermoelectric material selection, where m* is the density-of-states effective mass, me is the mass of an electron, μ is the carrier mobility, and κL is the lattice thermal conductivity. The β for magnesium silicides is 14, which is very high compared to 0.8 for iron silicides, 1.4 for manganese silicides, and 2.6 for silicon-germanium alloys. In this paper, basic phenomena of thermoelectricity and transport parameters for thermoelectric materials were briefly introduced, and thermoelectric properties of Mg2BIV synthesized by using a solid-state reaction were reviewed. In addition, various Mg2BIV compounds were discussed

Micro-Thermoelectric Generation Modules Fabricated with Low-Cost Mechanical Machining Processes

NASA Astrophysics Data System (ADS)

Liu, Dawei; Jin, A. J.; Peng, Wenbo; Li, Qiming; Gao, Hu; Zhu, Lianjun; Li, Fu; Zhu, Zhixiang

2017-05-01

Micro/small-scale thermoelectric generation modules are able to produce continuous, noise-free and reliable electricity power using low temperature differences that widely exist in nature or industry. These advantages bring them great application prospects in the fields of remote monitoring, microelectronics/micro-electromechanical systems (MEMS), medical apparatus and smart management system, which often require a power source free of maintenance and vibration. In this work, a prototypical thermoelectric module (12 mm × 12 mm × 0.8 mm) with 15 pairs of micro-scale thermoelectric legs (0.2 mm in width and 0.6 mm in height for each leg) is fabricated using a low-cost mechanical machining process. In this process, cutting and polishing are the main methods for the preparation of thermoelectric pairs from commercial polycrystalline materials and for the fabrication of electrode patterns. The as-fabricated module is tested for its power generation properties with the hot side heated by an electrical heater and the cold side by cold air. With the heater temperature of 375 K, the thermoelectric potential is about 9.1 mV, the short circuit current is about 14.5 mA, and the maximum output power is about 32.8 μW. The finite element method is applied to analyze the heat transfer of the module during our test. The temperature difference and heat flux are simulated, according to which the output powers at different temperatures are calculated, and the result is relatively consistent compared to the test results.

Heat reflecting tape for thermoelectric converter

DOEpatents

Purdy, David L.

1977-01-01

Threads are interlaced with thermoelectric wires to provide a woven cloth in tape form, there being an intermediate layer of heat radiation reflecting material (e.g., aluminum foil) insulated electrically from said wires, which are of opposite thermoelectric polarity and connected as a plurality of thermocouples.

Potential ability of zeolite to generate high-temperature vapor using waste heat

NASA Astrophysics Data System (ADS)

Fukai, Jun; Wijayanta, Agung Tri

2018-02-01

In various material product industries, a large amount of high temperature steam as heat sources are produced from fossil fuel, then thermal energy retained by condensed water at lower than 100°C are wasted. Thermal energies retained by exhaust gases at lower than 200°C are also wasted. Effective utilization of waste heat is believed to be one of important issues to solve global problems of energy and environment. Zeolite/water adsorption systems are introduced to recover such low-temperature waste heats in this study. Firstly, an adsorption steam recovery system was developed to generate high temperature steam from unused hot waste heat. The system used a new principle that adsorption heat of zeolite/water contact was efficiently extracted. A bench-scaled system was constructed, demonstrating contentious generation of saturated steam nearly 150°C from hot water at 80°C. Energy conservation is expected by returning the generated steam to steam lines in the product processes. Secondly, it was demonstrated that superheated steam/vapor at higher than 200°C could be generated from those at nearly 120°C using a laboratory-scaled setup. The maximum temperature and the time variation of output temperature were successfully estimated using macroscopic heat balances. Lastly, the maximum temperatures were estimated whose saturate air at the relative humidity 20-80% were heated by the present system. Theoretically, air at higher than 200°C was generated from saturate air at higher than 70°C. Consequently, zeolite/water adsorption systems have potential ability to regenerate thermal energy of waste water and exhaust gases.

Developing instrumentation to characterize thermoelectric generator modules.

PubMed

Liu, Dawei; Li, Qiming; Peng, Wenbo; Zhu, Lianjun; Gao, Hu; Meng, Qingsen; Jin, A J

2015-03-01

Based on the law of physics, known as "Seebeck effect," a thermoelectric generator (TEG) produces electricity when the temperature differential is applied across the TEG. This article reports a precision method in characterizing TEG modules. A precision instrument is constructed to study thermoelectric conversion in terms of output power and efficiency of TEG modules. The maximum allowable TEG module size is 150 mm, and the preferred size is from 30 mm to 60 mm. During measurements, the highest hot side temperature is 500 °C and the cold side temperature can be adjusted from room temperature to 100 °C. A mechanical structure is developed to control the pressure and parallelism of the clamping force of the TEG on both its hot and cold sides. A heat flux measurement module is installed at its cold side, and the heat flux through TEGs can be measured in position. Finally, the energy conversion efficiency of TEGs is calculated from experimental data of both an output power and a heat flux.

Printable thermoelectric devices and conductive patterns for medical applications

NASA Astrophysics Data System (ADS)

Lee, Jungmin; Kim, Hyunjung; Chen, Linfeng; Choi, Sang H.; Varadan, Vijay K.

2012-10-01

Remote point-of-care is expected to revolutionize the modern medical practice, and many efforts have been made for the development of wireless health monitoring systems for continuously detecting the physiological signals of patients. To make the remote point-of-care generally accepted and widely used, it is necessary to develop cost-effective and durable wireless health monitoring systems. Printing technique will be helpful for the fabrication of high-quality and low-cost medical devices and systems because it allows high-resolution and high-speed fabrication, low material consumption and nano-sized patterning on both flexible and rigid substrates. Furthermore, application of thermoelectric generators can replace conventional batteries as the power sources for wireless health monitoring systems because thermoelectric generators can convert the wasted heat or the heat from nature into electricity which is required for the operation of the wireless health monitoring systems. In this research, we propose the concept of printable thermoelectric devices and conductive patterns for the realization of more portable and cost-effective medical devices. To print thermoelectric generators and conductive patterns on substrates, printing inks with special characteristics should be developed. For the development of thermoelectric inks, nano-structured thermoelectric materials are synthesized and characterized; and for the development of conductive inks, two kinds of surface treated carbon nanotubes are used as active materials.

Spin-dependent heat and thermoelectric currents in a Rashba ring coupled to a photon cavity

NASA Astrophysics Data System (ADS)

Abdullah, Nzar Rauf; Tang, Chi-Shung; Manolescu, Andrei; Gudmundsson, Vidar

2018-01-01

Spin-dependent heat and thermoelectric currents in a quantum ring with Rashba spin-orbit interaction placed in a photon cavity are theoretically calculated. The quantum ring is coupled to two external leads with different temperatures. In a resonant regime, with the ring structure in resonance with the photon field, the heat and the thermoelectric currents can be controlled by the Rashba spin-orbit interaction. The heat current is suppressed in the presence of the photon field due to contribution of the two-electron and photon replica states to the transport while the thermoelectric current is not sensitive to changes in parameters of the photon field. Our study opens a possibility to use the proposed interferometric device as a tunable heat current generator in the cavity photon field.

A novel design for a wearable thermoelectric generator based on 3D fabric structure

NASA Astrophysics Data System (ADS)

Wu, Qian; Hu, Jinlian

2017-04-01

A flexible and wearable thermoelectric generator (TEG) could enable the conversion of human body heat into electrical power, which would help to realize a self-powered wearable electronic system. To overcome the difficulty of wearing existing flexible film TEGs, a novel 3D fabric TEG structure is designed in this study. By using a 3D fabric as the substrate and yarns coated with thermoelectric materials as legs, a wearable and flexible TEG can be realized. The designed generator has a sandwich structure, similar to the classical inorganic generator, which allows the generation of a temperature difference in the fabric thickness direction, thus making it wearable and showing promising application in body heat conversion. To verify the effectiveness of the designed generator structure, a prototype was fabricated, using a locknit spacer fabric as the substrate and yarns coated with waterborne polyurethane/carbon nanotube thermoelectric composites as legs. The results suggest that the fabricated spacer fabric TEG prototype could work successfully, although the performance of this prototype is of a low level. To further improve the efficiency of the 3D fabric generator and apply it in wearable electronics in the future, highly efficient inorganic thermoelectric materials can be applied, and modifications on the conductive connections can be made.

Thermodynamics of the mesoscopic thermoelectric heat engine beyond the linear-response regime.

PubMed

Yamamoto, Kaoru; Hatano, Naomichi

2015-10-01

Mesoscopic thermoelectric heat engine is much anticipated as a device that allows us to utilize with high efficiency wasted heat inaccessible by conventional heat engines. However, the derivation of the heat current in this engine seems to be either not general or described too briefly, even inappropriately in some cases. In this paper, we give a clear-cut derivation of the heat current of the engine with suitable assumptions beyond the linear-response regime. It resolves the confusion in the definition of the heat current in the linear-response regime. After verifying that we can construct the same formalism as that of the cyclic engine, we find the following two interesting results within the Landauer-Büttiker formalism: the efficiency of the mesoscopic thermoelectric engine reaches the Carnot efficiency if and only if the transmission probability is finite at a specific energy and zero otherwise; the unitarity of the transmission probability guarantees the second law of thermodynamics, invalidating Benenti et al.'s argument in the linear-response regime that one could obtain a finite power with the Carnot efficiency under a broken time-reversal symmetry [Phys. Rev. Lett. 106, 230602 (2011)]. These results demonstrate how quantum mechanics constrains thermodynamics.

Electric energy production by particle thermionic-thermoelectric power generators

NASA Technical Reports Server (NTRS)

Oettinger, P. E.

1980-01-01

Thermionic-thermoelectric power generators, composed of a thin layer of porous, low work function material separating a heated emitter electrode and a cooler collector electrode, have extremely large Seebeck coefficients of over 2 mV/K and can provide significant output power. Preliminary experiments with 20-micron thick (Ba Sr Ca)O coatings, limited by evaporative loss to temperatures below 1400 K, have yielded short circuit current densities of 500 mA/sq cm and power densities of 60 mW/ sq cm. Substantially more output is expected with cesium-coated refractory oxide particle coatings operating at higher temperatures. Practical generators will have thermal-to-electrical efficiencies of 10 to 20%. Further increases can be gained by cascading these high-temperature devices with lower temperature conventional thermoelectric generators.

Electrical performance analysis and economic evaluation of combined biomass cook stove thermoelectric (BITE) generator.

PubMed

Lertsatitthanakorn, C

2007-05-01

The use of biomass cook stoves is widespread in the domestic sector of developing countries, but the stoves are not efficient. To advance the versatility of the cook stove, we investigated the feasibility of adding a commercial thermoelectric (TE) module made of bismuth-telluride based materials to the stove's side wall, thereby creating a thermoelectric generator system that utilizes a proportion of the stove's waste heat. The system, a biomass cook stove thermoelectric generator (BITE), consists of a commercial TE module (Taihuaxing model TEP1-1264-3.4), a metal sheet wall which acts as one side of the stove's structure and serves as the hot side of the TE module, and a rectangular fin heat sink at the cold side of the TE module. An experimental set-up was built to evaluate the conversion efficiency at various temperature ranges. The experimental set-up revealed that the electrical power output and the conversion efficiency depended on the temperature difference between the cold and hot sides of the TE module. At a temperature difference of approximately 150 degrees C, the unit achieved a power output of 2.4W. The conversion efficiency of 3.2% was enough to drive a low power incandescent light bulb or a small portable radio. A theoretical model approximated the power output at low temperature ranges. An economic analysis indicated that the payback period tends to be very short when compared with the cost of the same power supplied by batteries. Therefore, the generator design formulated here could be used in the domestic sector. The system is not intended to compete with primary power sources but serves adequately as an emergency or backup source of power.

On the Placement of Thermoelectric Generators in Automobiles

NASA Astrophysics Data System (ADS)

Korzhuev, M. A.; Katin, I. V.

2010-09-01

The placement of thermoelectric generators (TEGs) in vehicles is analyzed, taking into account the interaction of the TEG with the internal combustion engine (ICE). Alternative locations of the TEG directly in the ICE, on the exhaust pipe, and on the cooling system are considered. In all three cases there is a conflict between the two thermal machines, which reduces the total efficiency of the thermodynamic (ICE + TEG) system. It is shown that the cause of the conflict is the low efficiency of the TEG ( η TEG < 0.05) compared with that of the ICE ( η TEG < 0.4); this conflict increases with the net power W e and decreases with increasing η TEG. For this reason, attainable values of W e, as well as waste heat recovery in cars by the TEG, are significantly limited. Also, some problems of finding materials for automotive TEGs and ways to suppress the parasitic Thomson effect in TEG legs are discussed.

Reduced energy consumption by massive thermoelectric waste heat recovery in light duty trucks

NASA Astrophysics Data System (ADS)

Magnetto, D.; Vidiella, G.

2012-06-01

The main objective of the EC funded HEATRECAR project is to reduce the energy consumption and curb CO2 emissions of vehicles by massively harvesting electrical energy from the exhaust system and re-use this energy to supply electrical components within the vehicle or to feed the power train of hybrid electrical vehicles. HEATRECAR is targeting light duty trucks and focuses on the development and the optimization of a Thermo Electric Generator (TEG) including heat exchanger, thermoelectric modules and DC/DC converter. The main objective of the project is to design, optimize and produce a prototype system to be tested on a 2.3l diesel truck. The base case is a Thermo Electric Generator (TEG) producing 1 KWel at 130 km/h. We present the system design and estimated output power from benchmark Bi2Te3 modules. We discuss key drivers for the optimization of the thermal-to-electric efficiency, such as materials, thermo-mechanical aspects and integration.

Ab Initio Assessment of the Thermoelectric Performance of Ruthenium-Doped Gadolinium Orthotantalate

NASA Technical Reports Server (NTRS)

Goldsby, Jon

2016-01-01

Solid state energy harvesting using waste heat available in gas turbine engine, offers potential for power generation to meet growing power needs of aircraft. Thermoelectric material advances offer new opportunities. Weight-optimized integrated turbine engine structure incorporating energy conversion devices.

Performance Analysis and Optimization of Concentrating Solar Thermoelectric Generator

NASA Astrophysics Data System (ADS)

Lamba, Ravita; Manikandan, S.; Kaushik, S. C.

2018-06-01

A thermodynamic model for a concentrating solar thermoelectric generator considering the Thomson effect combined with Fourier heat conduction, Peltier, and Joule heating has been developed and optimized in MATLAB environment. The temperatures at the hot and cold junctions of the thermoelectric generator were evaluated by solving the energy balance equations at both junctions. The effects of the solar concentration ratio, input electrical current, number of thermocouples, and electrical load resistance ratio on the power output and energy and exergy efficiencies of the system were studied. Optimization studies were carried out for the STEG system, and the optimum number of thermocouples, concentration ratio, and resistance ratio determined. The results showed that the optimum values of these parameters are different for conditions of maximum power output and maximum energy and exergy efficiency. The optimum values of the concentration ratio and load resistance ratio for maximum energy efficiency of 5.85% and maximum exergy efficiency of 6.29% were found to be 180 and 1.3, respectively, with corresponding power output of 4.213 W. Furthermore, at higher concentration ratio (C = 600), the optimum number of thermocouples was found to be 101 for maximum power output of 13.75 W, maximum energy efficiency of 5.73%, and maximum exergy efficiency of 6.16%. Moreover, the optimum number of thermocouple was the same for conditions of maximum power output and energy and exergy efficiency. The results of this study may provide insight for design of actual concentrated solar thermoelectric generator systems.

Solar thermoelectric generators

NASA Technical Reports Server (NTRS)

1977-01-01

The methods, the findings and the conclusions of a study for the design of a Solar Thermoelectric Generator (STG) intended for use as a power source for a spacecraft orbiting the planet Mercury are discussed. Several state-of-the-art thermoelectric technologies in the intended application were considered. The design of various STG configurations based on the thermoelectric technology selected from among the various technologies was examined in detail and a recommended STG design was derived. The performance characteristics of the selected STG technology and associated design were studied in detail as a function of the orbital characteristics of the STG in Mercury and throughout the orbit of Mercury around the sun.

The Influence of the Inner Topology of Cooling Units on the Performance of Automotive Exhaust-Based Thermoelectric Generators

NASA Astrophysics Data System (ADS)

Zhu, D. C.; Su, C. Q.; Deng, Y. D.; Wang, Y. P.; Liu, X.

2017-11-01

Automotive exhaust-based thermoelectric generators are currently a hot topic in energy recovery. The waste heat of automotive exhaust gas can be converted into electricity by means of thermoelectric modules. Generally, inserting fins into the cooling unit contributes to enhancing the heat transfer for a higher power output. However, the introduction of fins will result in a pressure drop in the cooling system. In current research, in order to enhance the heat transfer and avoid a large pressure drop, a cooling unit with cylindrical grooves on the interior surface was proposed. To evaluate the performance of the cylindrical grooves, different inner topologies, including a smooth interior surface,a smooth interior surface with inserted fins and an interior surface with cylindrical grooves, were compared. The results revealed that compared with the smooth interior surface, the smooth interior surface with inserted fins and the interior surface with cylindrical grooves both enhanced the heat transfer, but the interior surface with cylindrical grooves obtained a lower pressure drop. To improve the performance of the cylindrical grooves, different groove-depth ratios were tried, and the results showed that a groove-depth ratio of 0.081 could provide the best overall performance.

The Influence of the Inner Topology of Cooling Units on the Performance of Automotive Exhaust-Based Thermoelectric Generators

NASA Astrophysics Data System (ADS)

Zhu, D. C.; Su, C. Q.; Deng, Y. D.; Wang, Y. P.; Liu, X.

2018-06-01

Automotive exhaust-based thermoelectric generators are currently a hot topic in energy recovery. The waste heat of automotive exhaust gas can be converted into electricity by means of thermoelectric modules. Generally, inserting fins into the cooling unit contributes to enhancing the heat transfer for a higher power output. However, the introduction of fins will result in a pressure drop in the cooling system. In current research, in order to enhance the heat transfer and avoid a large pressure drop, a cooling unit with cylindrical grooves on the interior surface was proposed. To evaluate the performance of the cylindrical grooves, different inner topologies, including a smooth interior surface,a smooth interior surface with inserted fins and an interior surface with cylindrical grooves, were compared. The results revealed that compared with the smooth interior surface, the smooth interior surface with inserted fins and the interior surface with cylindrical grooves both enhanced the heat transfer, but the interior surface with cylindrical grooves obtained a lower pressure drop. To improve the performance of the cylindrical grooves, different groove-depth ratios were tried, and the results showed that a groove-depth ratio of 0.081 could provide the best overall performance.

Thermal power generation during heat cycle near room temperature

NASA Astrophysics Data System (ADS)

Shibata, Takayuki; Fukuzumi, Yuya; Kobayashi, Wataru; Moritomo, Yutaka

2018-01-01

We demonstrate that a sodium-ion secondary battery (SIB)-type thermocell consisting of two types of Prussian blue analogue (PBA) with different electrochemical thermoelectric coefficients (S EC ≡ ∂V/∂T V and T are the redox potential and temperature, respectively) produces electrical energy during heat cycles. The device produces an electrical energy of 2.3 meV/PBA per heat cycle between 295 K (= T L) and 323 K (= T H). The ideal thermal efficiency (η = 1.0%), which is evaluated using the heat capacity (C = 4.16 meV/K) of ideal Na2Co[Fe(CN)6], reaches 11% of the Carnot efficiency (ηth = 8.7%). Our SIB-type thermocell is a promising thermoelectric device that harvests waste heat near room temperature.

Lead telluride as a thermoelectric material for thermoelectric power generation

NASA Astrophysics Data System (ADS)

Dughaish, Z. H.

2002-09-01

The specialized applications of thermoelectric generators are very successful and have motivated a search for materials with an improved figure of merit Z, and also for materials which operate at elevated temperatures. Lead telluride, PbTe, is an intermediate thermoelectric power generator. Its maximum operating temperature is 900 K. PbTe has a high melting point, good chemical stability, low vapor pressure and good chemical strength in addition to high figure of merit Z. Recently, research in thermoelectricity aims to obtain new improved materials for autonomous sources of electrical power in specialized medical, terrestial and space applications and to obtain an unconventional energy source after the oil crises of 1974. Although the efficiency of thermoelectric generators is rather low, typically ∼5%, the other advantages, such as compactness, silent, reliability, long life, and long period of operation without attention, led to a wide range of applications. PbTe thermoelectric generators have been widely used by the US army, in space crafts to provide onboard power, and in pacemakers batteries. The general physical properties of lead telluride and factors affecting the figure of merit have been reviewed. Various possibilities of improving the figure of merit of the material have been given, including effect of grain size on reducing the lattice thermal conductivity λL. Comparison of some transport properties of lead telluride with other thermoelectric materials and procedures of preparing compacts with transport properties very close to the single crystal values from PbTe powder by cold and hot-pressing techniques are discussed.

Development of Thermoelectric Power Generation and Peltier Cooling Properties of Materials for Thermoelectric Cryocooling Devices

DTIC Science & Technology

2015-05-12

method. AAMU would like to continue, given future research funding, with our new design for the thermoelectric and photovoltaic systems and hybrid...nanofabrication to develop nanostructured thermoelectric (TE) materials for application in high-efficiency thermoelectric power generators and solid...Distribution Unlimited Final Report: Development of Thermoelectric Power Generation and Peltier Cooling Properties of Materials for Thermoelectric

n-type thermoelectric material Mg2Sn0.75Ge0.25 for high power generation

PubMed Central

Liu, Weishu; Kim, Hee Seok; Chen, Shuo; Jie, Qing; Lv, Bing; Yao, Mengliang; Ren, Zhensong; Opeil, Cyril P.; Wilson, Stephen; Chu, Ching-Wu; Ren, Zhifeng

2015-01-01

Thermoelectric power generation is one of the most promising techniques to use the huge amount of waste heat and solar energy. Traditionally, high thermoelectric figure-of-merit, ZT, has been the only parameter pursued for high conversion efficiency. Here, we emphasize that a high power factor (PF) is equivalently important for high power generation, in addition to high efficiency. A new n-type Mg2Sn-based material, Mg2Sn0.75Ge0.25, is a good example to meet the dual requirements in efficiency and output power. It was found that Mg2Sn0.75Ge0.25 has an average ZT of 0.9 and PF of 52 μW⋅cm−1⋅K−2 over the temperature range of 25–450 °C, a peak ZT of 1.4 at 450 °C, and peak PF of 55 μW⋅cm−1⋅K−2 at 350 °C. By using the energy balance of one-dimensional heat flow equation, leg efficiency and output power were calculated with Th = 400 °C and Tc = 50 °C to be of 10.5% and 6.6 W⋅cm−2 under a temperature gradient of 150 °C⋅mm−1, respectively. PMID:25733845

Testing and Optimizing a Stove-Powered Thermoelectric Generator with Fan Cooling.

PubMed

Zheng, Youqu; Hu, Jiangen; Li, Guoneng; Zhu, Lingyun; Guo, Wenwen

2018-06-07

In order to provide heat and electricity under emergency conditions in off-grid areas, a stove-powered thermoelectric generator (STEG) was designed and optimized. No battery was incorporated, ensuring it would work anytime, anywhere, as long as combustible materials were provided. The startup performance, power load feature and thermoelectric (TE) efficiency were investigated in detail. Furthermore, the heat-conducting plate thickness, cooling fan selection, heat sink dimension and TE module configuration were optimized. The heat flow method was employed to determine the TE efficiency, which was compared to the predicted data. Results showed that the STEG can supply clean-and-warm air (625 W) and electricity (8.25 W at 5 V) continuously at a temperature difference of 148 °C, and the corresponding TE efficiency was measured to be 2.31%. Optimization showed that the choice of heat-conducting plate thickness, heat sink dimensions and cooling fan were inter-dependent, and the TE module configuration affected both the startup process and the power output.

Improvement in thermoelectric power factor of mechanically alloyed p-type SiGe by incorporation of TiB{sub 2}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahmad, Sajid, E-mail: sajidahmadiitkgp@gmail.com; Dubey, K.; Bhattacharya, Shovit

2016-05-23

Nearly 60% of the world’s useful energy is wasted as heat and recovering a fraction of this waste heat by converting it as useful electrical power is an important area of research{sup [1]}. Thermoelectric power generators (TEG) are solid state devices which converts heat into electricity. TEG consists of n and p-type thermoelements connected electrically in series and thermally in parallel{sup [2]}. Silicon germanium (SiGe) alloy is one of the conventional high temperature thermoelectric materials and is being used in radio-isotopes based thermoelectric power generators for deep space exploration programs.Temperature (T) dependence of thermoelectric (TE) properties of p-type SiGe andmore » p-type SiGe-x wt.%TiB{sub 2} (x=6,8,10%) nanocomposite materials has been studied with in the temperature range of 300 K to 1100 K. It is observed that there is an improvement in the power factor (α{sup 2}/ρ) of SiGe alloy on addition of TiB{sub 2} upto 8 wt.% that is mainly due to increase in the Seebeck coefficient (α) and electrical conductivity (σ) of the alloy.« less

Thermodynamics of the mesoscopic thermoelectric heat engine beyond the linear-response regime

NASA Astrophysics Data System (ADS)

Yamamoto, Kaoru; Hatano, Naomichi

2015-10-01

Mesoscopic thermoelectric heat engine is much anticipated as a device that allows us to utilize with high efficiency wasted heat inaccessible by conventional heat engines. However, the derivation of the heat current in this engine seems to be either not general or described too briefly, even inappropriately in some cases. In this paper, we give a clear-cut derivation of the heat current of the engine with suitable assumptions beyond the linear-response regime. It resolves the confusion in the definition of the heat current in the linear-response regime. After verifying that we can construct the same formalism as that of the cyclic engine, we find the following two interesting results within the Landauer-Büttiker formalism: the efficiency of the mesoscopic thermoelectric engine reaches the Carnot efficiency if and only if the transmission probability is finite at a specific energy and zero otherwise; the unitarity of the transmission probability guarantees the second law of thermodynamics, invalidating Benenti et al.'s argument in the linear-response regime that one could obtain a finite power with the Carnot efficiency under a broken time-reversal symmetry [Phys. Rev. Lett. 106, 230602 (2011), 10.1103/PhysRevLett.106.230602]. These results demonstrate how quantum mechanics constrains thermodynamics.

Analysis of the Effect of Module Thickness Reduction on Thermoelectric Generator Output

NASA Astrophysics Data System (ADS)

Brito, F. P.; Figueiredo, L.; Rocha, L. A.; Cruz, A. P.; Goncalves, L. M.; Martins, J.; Hall, M. J.

2016-03-01

Conventional thermoelectric generators (TEGs) used in applications such as exhaust heat recovery are typically limited in terms of power density due to their low efficiency. Additionally, they are generally costly due to the bulk use of rare-earth elements such as tellurium. If less material could be used for the same output, then the power density and the overall cost per kilowatt (kW) of electricity produced could drop significantly, making TEGs a more attractive solution for energy harvesting of waste heat. The present work assesses the effect of reducing the amount of thermoelectric (TE) material used (namely by reducing the module thickness) on the electrical output of conventional bismuth telluride TEGs. Commercial simulation packages (ANSYS CFX and thermal-electric) and bespoke models were used to simulate the TEGs at various degrees of detail. Effects such as variation of the thermal and electrical contact resistance and the component thickness and the effect of using an element supporting matrix (e.g., eggcrate) instead of having air conduction in void areas have been assessed. It was found that indeed it is possible to reduce the use of bulk TE material while retaining power output levels equivalent to thicker modules. However, effects such as thermal contact resistance were found to become increasingly important as the active TE material thickness was decreased.

Modeling of Thermoelectric Generator Power Characteristics for Motorcycle-Type Engines

NASA Astrophysics Data System (ADS)

Osipkov, Alexey; Poshekhonov, Roman; Arutyunyan, Georgy; Basov, Andrey; Safonov, Roman

2017-10-01

Thermoelectric generation in vehicles such as motorcycles, all-terrain vehicles, and snowmobiles opens the possibility of additional electrical energy generation by means of exhaust heat utilization. This is beneficial because replacing the mechanical generator used in such vehicles with a more powerful one in cases of electrical power deficiency is impossible. This paper proposes a calculation model for the thermoelectric generator (TEG) operational characteristics of the low-capacity internal combustion engines used in these vehicles. Two TEG structures are considered: (1) TEG with air cooling and (2) TEG with water cooling. Modeling consists of two calculation stages. In the first stage, the heat exchange coefficients of the hot and cold exchangers are determined using computational fluid dynamics. In the second stage, the TEG operational characteristics are modeled based on the nonlinear equations of the heat transfer and power balance. On the basis of the modeling results, the dependence of the TEG's major operating characteristics (such as the electrical power generated by the TEG and its efficiency and mass) on operating conditions or design parameters is determined. For example, the electrical power generated by a TEG for a Yamaha WR450F motorcycle engine with a volume of 0.449 × 10-3 m3 was calculated to be as much as 100 W. Use of the TEG arrangements proposed is justified by the additional electrical power generation for small capacity vehicles, without the need for internal combustion engine redesign.

Integrating Phase-Change Materials into Automotive Thermoelectric Generators

NASA Astrophysics Data System (ADS)

Klein Altstedde, Mirko; Rinderknecht, Frank; Friedrich, Horst

2014-06-01

Because the heat emitted by conventional combustion-engine vehicles during operation has highly transient properties, automotive thermoelectric generators (TEG) are intended for a particular operating state (design point). This, however, leads to two problems. First, whenever the combustion engine runs at low load, the maximum operating temperature cannot be properly utilised; second, a combustion engine at high load requires partial diversion of exhaust gas away from the TEG to protect the thermoelectric modules. An attractive means of stabilising dynamic exhaust behaviour (thereby keeping the TEG operating status at the design point for as long as possible) is use of latent heat storage, also known as phase-change materials (PCM). By positioning PCM between module and exhaust heat conduit, and choosing a material with a phase-change temperature matching the module's optimum operating temperature, it can be used as heat storage. This paper presents results obtained during examination of the effect of integration of latent heat storage on the potential of automotive TEG to convert exhaust heat. The research resulted in the development of a concept based on the initial integration idea, followed by proof of concept by use of a specially created prototype. In addition, the potential amount of energy obtained by use of a PCM-equipped TEG was calculated. The simulations indicated a significant increase in electrical energy was obtained in the selected test cycle.

Carbon-Nanotube-Based Thermoelectric Materials and Devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blackburn, Jeffrey L.; Ferguson, Andrew J.; Cho, Chungyeon

Conversion of waste heat to voltage has the potential to significantly reduce the carbon footprint of a number of critical energy sectors, such as the transportation and electricity-generation sectors, and manufacturing processes. Thermal energy is also an abundant low-flux source that can be harnessed to power portable/wearable electronic devices and critical components in remote off-grid locations. As such, a number of different inorganic and organic materials are being explored for their potential in thermoelectric-energy-harvesting devices. Carbon-based thermoelectric materials are particularly attractive due to their use of nontoxic, abundant source-materials, their amenability to high-throughput solution-phase fabrication routes, and the high specificmore » energy (i.e., W g-1) enabled by their low mass. Single-walled carbon nanotubes (SWCNTs) represent a unique 1D carbon allotrope with structural, electrical, and thermal properties that enable efficient thermoelectric-energy conversion. Here, the progress made toward understanding the fundamental thermoelectric properties of SWCNTs, nanotube-based composites, and thermoelectric devices prepared from these materials is reviewed in detail. This progress illuminates the tremendous potential that carbon-nanotube-based materials and composites have for producing high-performance next-generation devices for thermoelectric-energy harvesting.« less

Carbon-Nanotube-Based Thermoelectric Materials and Devices

DOE PAGES

Blackburn, Jeffrey L.; Ferguson, Andrew J.; Cho, Chungyeon; ...

2018-01-22

Conversion of waste heat to voltage has the potential to significantly reduce the carbon footprint of a number of critical energy sectors, such as the transportation and electricity-generation sectors, and manufacturing processes. Thermal energy is also an abundant low-flux source that can be harnessed to power portable/wearable electronic devices and critical components in remote off-grid locations. As such, a number of different inorganic and organic materials are being explored for their potential in thermoelectric-energy-harvesting devices. Carbon-based thermoelectric materials are particularly attractive due to their use of nontoxic, abundant source-materials, their amenability to high-throughput solution-phase fabrication routes, and the high specificmore » energy (i.e., W g-1) enabled by their low mass. Single-walled carbon nanotubes (SWCNTs) represent a unique 1D carbon allotrope with structural, electrical, and thermal properties that enable efficient thermoelectric-energy conversion. Here, the progress made toward understanding the fundamental thermoelectric properties of SWCNTs, nanotube-based composites, and thermoelectric devices prepared from these materials is reviewed in detail. This progress illuminates the tremendous potential that carbon-nanotube-based materials and composites have for producing high-performance next-generation devices for thermoelectric-energy harvesting.« less

Carbon-Nanotube-Based Thermoelectric Materials and Devices.

PubMed

Blackburn, Jeffrey L; Ferguson, Andrew J; Cho, Chungyeon; Grunlan, Jaime C

2018-03-01

Conversion of waste heat to voltage has the potential to significantly reduce the carbon footprint of a number of critical energy sectors, such as the transportation and electricity-generation sectors, and manufacturing processes. Thermal energy is also an abundant low-flux source that can be harnessed to power portable/wearable electronic devices and critical components in remote off-grid locations. As such, a number of different inorganic and organic materials are being explored for their potential in thermoelectric-energy-harvesting devices. Carbon-based thermoelectric materials are particularly attractive due to their use of nontoxic, abundant source-materials, their amenability to high-throughput solution-phase fabrication routes, and the high specific energy (i.e., W g -1 ) enabled by their low mass. Single-walled carbon nanotubes (SWCNTs) represent a unique 1D carbon allotrope with structural, electrical, and thermal properties that enable efficient thermoelectric-energy conversion. Here, the progress made toward understanding the fundamental thermoelectric properties of SWCNTs, nanotube-based composites, and thermoelectric devices prepared from these materials is reviewed in detail. This progress illuminates the tremendous potential that carbon-nanotube-based materials and composites have for producing high-performance next-generation devices for thermoelectric-energy harvesting. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nano-materials enabled thermoelectricity from window glasses.

PubMed

Inayat, Salman B; Rader, Kelly R; Hussain, Muhammad M

2012-01-01

With a projection of nearly doubling up the world population by 2050, we need wide variety of renewable and clean energy sources to meet the increased energy demand. Solar energy is considered as the leading promising alternate energy source with the pertinent challenge of off sunshine period and uneven worldwide distribution of usable sun light. Although thermoelectricity is considered as a reasonable renewable energy from wasted heat, its mass scale usage is yet to be developed. Here we show, large scale integration of nano-manufactured pellets of thermoelectric nano-materials, embedded into window glasses to generate thermoelectricity using the temperature difference between hot outside and cool inside. For the first time, this work offers an opportunity to potentially generate 304 watts of usable power from 9 m(2) window at a 20°C temperature gradient. If a natural temperature gradient exists, this can serve as a sustainable energy source for green building technology.

The relationship between the thermoelectric generator efficiency and the device engineering figure of merit Zd,eng. The maximum efficiency 𝜼max

NASA Astrophysics Data System (ADS)

Hapenciuc, C. L.; Borca-Tasciuc, T.; Mihailescu, I. N.

2017-04-01

Thermoelectric materials are used today in thermoelectric devices for heat to electricity(thermoelectric generators-TEG) or electricity to heat(heat pumps) conversion in a large range of applications. In the case of TEGs the final measure of their performance is given by a quantity named the maximum efficiency which shows how much from the heat input is converted into electrical power. Therefore it is of great interest to know correctly how much is the efficiency of a device to can make commercial assessments. The concept of engineering figure of merit, Zeng, and engineering power factor, Peng, were already introduced in the field to quantify the efficiency of a single material under temperature dependent thermoelectric properties, with the mention that the formulas derivation was limited to one leg of the thermoelectric generator. In this paper we propose to extend the concept of engineering figure of merit to a thermoelectric generator by introducing a more general concept of device engineering thermoelectric figure of merit, Zd,eng, which depends on the both TEG materials properties and which shall be the right quantity to be used when we are interested in the evaluation of the efficiency. Also, this work takes into account the electrical contact resistance between the electrodes and thermoelement legs in an attempt to quantify its influence upon the performance of a TEG. Finally, a new formula is proposed for the maximum efficiency of a TEG.

Irreversibilities and efficiency at maximum power of heat engines: the illustrative case of a thermoelectric generator.

PubMed

Apertet, Y; Ouerdane, H; Goupil, C; Lecoeur, Ph

2012-03-01

Energy conversion efficiency at maximum output power, which embodies the essential characteristics of heat engines, is the main focus of the present work. The so-called Curzon and Ahlborn efficiency η(CA) is commonly believed to be an absolute reference for real heat engines; however, a different but general expression for the case of stochastic heat engines, η(SS), was recently found and then extended to low-dissipation engines. The discrepancy between η(CA) and η(SS) is here analyzed considering different irreversibility sources of heat engines, of both internal and external types. To this end, we choose a thermoelectric generator operating in the strong-coupling regime as a physical system to qualitatively and quantitatively study the impact of the nature of irreversibility on the efficiency at maximum output power. In the limit of pure external dissipation, we obtain η(CA), while η(SS) corresponds to the case of pure internal dissipation. A continuous transition between from one extreme to the other, which may be operated by tuning the different sources of irreversibility, also is evidenced.

Progress towards an Optimization Methodology for Combustion-Driven Portable Thermoelectric Power Generation Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krishnan, Shankar; Karri, Naveen K.; Gogna, Pawan K.

2012-03-13

Enormous military and commercial interests exist in developing quiet, lightweight, and compact thermoelectric (TE) power generation systems. This paper investigates design integration and analysis of an advanced TE power generation system implementing JP-8 fueled combustion and thermal recuperation. Design and development of a portable TE power system using a JP-8 combustor as a high temperature heat source and optimal process flows depend on efficient heat generation, transfer, and recovery within the system are explored. Design optimization of the system required considering the combustion system efficiency and TE conversion efficiency simultaneously. The combustor performance and TE sub-system performance were coupled directlymore » through exhaust temperatures, fuel and air mass flow rates, heat exchanger performance, subsequent hot-side temperatures, and cold-side cooling techniques and temperatures. Systematic investigation of this system relied on accurate thermodynamic modeling of complex, high-temperature combustion processes concomitantly with detailed thermoelectric converter thermal/mechanical modeling. To this end, this work reports on design integration of systemlevel process flow simulations using commercial software CHEMCADTM with in-house thermoelectric converter and module optimization, and heat exchanger analyses using COMSOLTM software. High-performance, high-temperature TE materials and segmented TE element designs are incorporated in coupled design analyses to achieve predicted TE subsystem level conversion efficiencies exceeding 10%. These TE advances are integrated with a high performance microtechnology combustion reactor based on recent advances at the Pacific Northwest National Laboratory (PNNL). Predictions from this coupled simulation established a basis for optimal selection of fuel and air flow rates, thermoelectric module design and operating conditions, and microtechnology heat-exchanger design criteria. This paper will discuss

An electronic cryoprobe for cryosurgery using heat pipes and thermoelectric coolers: a preliminary report.

PubMed

Hamilton, A; Hu, J

1993-01-01

A hand-held fully electrically powered and programmable cryoprobe for general-purpose cryosurgery and cryotherapy has been developed. By combining the technologies of thermoelectric cooling and heat pipes, the temperature at the tip of the probe can easily reach -50 to -60 degrees C. It can hold below -40 degrees C when it cools a load of 10 W at the tip. Previous efforts developing cryoprobes made of thermoelectric modules have been hindered by the inherent characteristics of commercially available thermoelectric coolers: low efficiency, size and inflexible shape and very sensitive to heat intensity and thermal insulation. Matching thermoelectrics with heat pipes uses the advantages of both technologies. In the cryoprobe the heat pipe is used to focus and transport the cooling power of multi-thermoelectric modules. The heat flux for the thermoelectric modules is reduced and their efficiencies are increased. The transport of heat by a heat pipe also allows flexible access to treated spots of patients.

Thermoelectric Exhaust Heat Recovery with Heat Pipe-Based Thermal Control

NASA Astrophysics Data System (ADS)

Brito, F. P.; Martins, Jorge; Hançer, Esra; Antunes, Nuno; Gonçalves, L. M.

2015-06-01

Heat pipe (HP)-based heat exchangers can be used for very low resistance heat transfer between a hot and a cold source. Their operating temperature depends solely on the boiling point of their working fluid, so it is possible to control the heat transfer temperature if the pressure of the HP can be adjusted. This is the case of the variable conductance HPs (VCHP). This solution makes VCHPs ideal for the passive control of thermoelectric generator (TEG) temperature levels. The present work assesses, both theoretically and experimentally, the merit of the aforementioned approach. A thermal and electrical model of a TEG with VCHP assist is proposed. Experimental results obtained with a proof of concept prototype attached to a small single-cylinder engine are presented and used to validate the model. It was found that the HP heat exchanger indeed enables the TEG to operate at a constant, optimal temperature in a passive and safe way, and with a minimal overall thermal resistance, under part load, it effectively reduces the active module area without deprecating the temperature level of the active modules.

Micro/Nano Fabricated Solid-State Thermoelectric Generator Devices for Integrated High Voltage Power Sources

NASA Astrophysics Data System (ADS)

Fleurial, J.-P.; Ryan, M. A.; Snyder, G. J.; Huang, C.-K.; Whitacre, J. F.; Patel, J.; Lim, J.; Borshchevsky, A.

2002-01-01

Deep space missions have a strong need for compact, high power density, reliable and long life electrical power generation and storage under extreme temperature conditions. Except for electrochemical batteries and solar cells, there are currently no available miniaturized power sources. Conventional power generators devices become inefficient in extreme environments (such as encountered in Mars, Venus or outer planet missions) and rechargeable energy storage devices can only be operated in a narrow temperature range thereby limiting mission duration. The planned development of much smaller spacecrafts incorporating a variety of micro/nanodevices and miniature vehicles will require novel, reliable power technologies. It is also expected that such micro power sources could have a wide range of terrestrial applications, in particular when the limited lifetime and environmental limitations of batteries are key factors. Advanced solid-state thermoelectric combined with radioisotope or waste heat sources and low profile energy storage devices are ideally suited for these applications. The Jet Propulsion Laboratory has been actively pursuing the development of thermoelectric micro/nanodevices that can be fabricated using a combination of electrochemical deposition and integrated circuit processing techniques. Some of the technical challenges associated with these micro/nanodevice concepts, their expected level of performance and experimental fabrication and testing results to date are presented and discussed.

Feasibility survey of thermoelectric conversion technology using semiconductors

NASA Astrophysics Data System (ADS)

1993-03-01

The paper takes notice to thermoelectric conversion technology using semiconductors and investigates it in a wide range from high temperature to low temperature to study its feasibility. It is found that in Bi-Te alloy elements applicable to a temperature range of around 200(degree)C, some are over 3.5(times)10(sup -3)K(sup -1) in performance index, and performance of the element can be practically improved in the near future. The thermoelectric power generation system using waste heat from the fuel cell power plant, which is 5-6% in conversion efficiency, can generate output more than 100kW and is expected to improve by approximately 1% in plant overall efficiency. The construction cost, however, is around 1.6-1.9 million yen/kW. The thermoelectric power generation plant which is modeled on No.2 generator of Hatchobaru geothermal power plant can generate electric output of 10-12.5MW, which is smaller than that of the conventional geothermal power generation. The construction cost is around 3.2-4.1 million yen/kW. Even if advantage of the system in running cost is considered, attractive systematization seems to be difficult.

Tailored semiconducting carbon nanotube networks with enhanced thermoelectric properties

DOE PAGES

Avery, Azure D.; Zhou, Ben H.; Lee, Jounghee; ...

2016-04-04

Thermoelectric power generation, allowing recovery of part of the energy wasted as heat, is emerging as an important component of renewable energy and energy efficiency portfolios. Although inorganic semiconductors have traditionally been employed in thermoelectric applications, organic semiconductors garner increasing attention as versatile thermoelectric materials. Here we present a combined theoretical and experimental study suggesting that semiconducting single-walled carbon nanotubes with carefully controlled chirality distribution and carrier density are capable of large thermoelectric power factors, higher than 340 μW m -1 K -2, comparable to the best-performing conducting polymers and larger than previously observed for carbon nanotube films. Furthermore, wemore » demonstrate that phonons are the dominant source of thermal conductivity in the networks, and that our carrier doping process significantly reduces the thermal conductivity relative to undoped networks. As a result, these findings provide the scientific underpinning for improved functional organic thermoelectric composites with carbon nanotube inclusions.« less

Tailored semiconducting carbon nanotube networks with enhanced thermoelectric properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Avery, Azure D.; Zhou, Ben H.; Lee, Jounghee

Thermoelectric power generation, allowing recovery of part of the energy wasted as heat, is emerging as an important component of renewable energy and energy efficiency portfolios. Although inorganic semiconductors have traditionally been employed in thermoelectric applications, organic semiconductors garner increasing attention as versatile thermoelectric materials. Here we present a combined theoretical and experimental study suggesting that semiconducting single-walled carbon nanotubes with carefully controlled chirality distribution and carrier density are capable of large thermoelectric power factors, higher than 340 μW m -1 K -2, comparable to the best-performing conducting polymers and larger than previously observed for carbon nanotube films. Furthermore, wemore » demonstrate that phonons are the dominant source of thermal conductivity in the networks, and that our carrier doping process significantly reduces the thermal conductivity relative to undoped networks. As a result, these findings provide the scientific underpinning for improved functional organic thermoelectric composites with carbon nanotube inclusions.« less

Thermoelectric generator based on composites obtained by sintering of detonation nanodiamonds

NASA Astrophysics Data System (ADS)

Eidelman, E. D.; Meilakhs, A. P.; Semak, B. V.; Shakhov, F. M.

2017-11-01

A model of a thermoelectric generator is proposed, in which composite materials obtained by sintering diamond nanoparticles are used as the main component. To increase the useful conversion of heat into electric current, it is proposed to use the effect of electron drag by ballistic phonons. To reduce the ineffective heat spread, it is proposed to use the effect of thermal resistance of the boundaries between the graphite-like and diamond-like phases of the composite. An experimental confirmation of the existence of an optimal volume ratio between graphite-like and diamond-like phases of the composite is predicted and obtained. The highest achieved value of thermoelectric coefficient in the actual structure is 80 µV K-1 (which means 20 times increase compared to that of composites not of the optimal structure), with a thermal conductivity of 50 W m-1 K-1. These results were obtained with constant electrical conductivity. The combined influence of these two effects in case of the ideal composite structure should result in an increase of the thermoelectric efficiency parameter by three orders of magnitude.

Cooling device featuring thermoelectric and diamond materials for temperature control of heat-dissipating devices

NASA Technical Reports Server (NTRS)

Vandersande, Ian W. (Inventor); Ewell, Richard (Inventor); Fleurial, Jean-Pierre (Inventor); Lyon, Hylan B. (Inventor)

1998-01-01

A cooling device for lowering the temperature of a heat-dissipating device. The cooling device includes a heat-conducting substrate (composed, e.g., of diamond or another high thermal conductivity material) disposed in thermal contact with the heat-dissipating device. During operation, heat flows from the heat-dissipating device into the heat-conducting substrate, where it is spread out over a relatively large area. A thermoelectric cooling material (e.g., a Bi.sub.2 Te.sub.3 -based film or other thermoelectric material) is placed in thermal contact with the heat-conducting substrate. Application of electrical power to the thermoelectric material drives the thermoelectric material to pump heat into a second heat-conducting substrate which, in turn, is attached to a heat sink.

Thermoelectric Energy Harvesting Using Phase Change Materials (PCMs) in High Temperature Environments in Aircraft

NASA Astrophysics Data System (ADS)

Elefsiniotis, A.; Becker, Th.; Schmid, U.

2014-06-01

Wireless, energy-autonomous structural health-monitoring systems in aircraft have the potential of reducing total maintenance costs. Thermoelectric energy harvesting, which seems the best choice for creating truly autonomous health monitoring sensors, is the principle behind converting waste heat to useful electrical energy through the use of thermoelectric generators. To enhance the temperature difference across the two sides of a thermoelectric generator, i.e. increasing heat flux and energy production, a phase change material acting as thermal mass is attached on one side of the thermoelectric generators while the other side is placed on the aircraft structure. The application area under investigation for this paper is the pylon aft fairing, located near the engine of an aircraft, with temperatures reaching on the inside up to 350 °C. Given these harsh operational conditions, the performance of a device, containing erythritol as a phase change material, is evaluated. The harvested energy reaching values up to 81.4 J can be regulated by a power management module capable of storing the excess energy and recovering it from the medium powering a sensor node and a wireless transceiver.

Method of operating a thermoelectric generator

DOEpatents

Reynolds, Michael G; Cowgill, Joshua D

2013-11-05

A method for operating a thermoelectric generator supplying a variable-load component includes commanding the variable-load component to operate at a first output and determining a first load current and a first load voltage to the variable-load component while operating at the commanded first output. The method also includes commanding the variable-load component to operate at a second output and determining a second load current and a second load voltage to the variable-load component while operating at the commanded second output. The method includes calculating a maximum power output of the thermoelectric generator from the determined first load current and voltage and the determined second load current and voltage, and commanding the variable-load component to operate at a third output. The commanded third output is configured to draw the calculated maximum power output from the thermoelectric generator.

Thermoelectric Generators Based on Ionic Liquids

NASA Astrophysics Data System (ADS)

Laux, Edith; Uhl, Stefanie; Jeandupeux, Laure; López, Pilar Pérez; Sanglard, Pauline; Vanoli, Ennio; Marti, Roger; Keppner, Herbert

2018-06-01

Looking at energy harvesting using body or waste heat for portable electronic or on-board devices, Ionic liquids are interesting candidates as thermoactive materials in thermoelectric generators (TEGs) because of their outstanding properties. Two different kinds of ionic liquid, with alkylammonium and choline as cations, were studied, whereby different anions and redox couples were combined. This study focussed on the intention to find non-hazardous and environmentally friendly ionic liquids for TEGs to be selected among the thousands that can potentially be used. Seebeck coefficients (SEs) as high as - 15 mV/K were measured, in a particular case for an electrode temperature difference of 20 K. The bottleneck of our TEG device is still the abundance of negative SE liquids matching the internal resistance with the existing positive SE-liquids at series connections. In this paper, we show further progress in finding increased negative SE liquids. For current extraction from the TEG, the ionic liquid must be blended with a redox couple, allowing carrier exchange in a cyclic process under a voltage which is incuced by the asymmetry of the generator in terms of hot and cold electrodes. In our study, two types of redox pairs were tested. It was observed that a high SE of an ionic liquid/redox blend is not a sufficient condition for high power output. It appears that more complex effects between the ionic liquid and the electrode determine the magnitude of the final current/power output. The physico-chemical understanding of such a TEG cell is not yet available.

Thermoelectric Generators Based on Ionic Liquids

NASA Astrophysics Data System (ADS)

Laux, Edith; Uhl, Stefanie; Jeandupeux, Laure; López, Pilar Pérez; Sanglard, Pauline; Vanoli, Ennio; Marti, Roger; Keppner, Herbert

2018-03-01

Looking at energy harvesting using body or waste heat for portable electronic or on-board devices, Ionic liquids are interesting candidates as thermoactive materials in thermoelectric generators (TEGs) because of their outstanding properties. Two different kinds of ionic liquid, with alkylammonium and choline as cations, were studied, whereby different anions and redox couples were combined. This study focussed on the intention to find non-hazardous and environmentally friendly ionic liquids for TEGs to be selected among the thousands that can potentially be used. Seebeck coefficients (SEs) as high as - 15 mV/K were measured, in a particular case for an electrode temperature difference of 20 K. The bottleneck of our TEG device is still the abundance of negative SE liquids matching the internal resistance with the existing positive SE-liquids at series connections. In this paper, we show further progress in finding increased negative SE liquids. For current extraction from the TEG, the ionic liquid must be blended with a redox couple, allowing carrier exchange in a cyclic process under a voltage which is incuced by the asymmetry of the generator in terms of hot and cold electrodes. In our study, two types of redox pairs were tested. It was observed that a high SE of an ionic liquid/redox blend is not a sufficient condition for high power output. It appears that more complex effects between the ionic liquid and the electrode determine the magnitude of the final current/power output. The physico-chemical understanding of such a TEG cell is not yet available.

High efficiency thermoelectric power generation using Zintl-type materials

NASA Technical Reports Server (NTRS)

Brown, Shawna (Inventor); Snyder, G. Jeffrey (Inventor); Gascoin, Franck (Inventor); Kauzlarich, Susan (Inventor)

2010-01-01

The invention disclosed herein relates to thermoelectrically-active p-type Zintl phase materials as well as devices utilizing such compounds. Such thermoelectric materials and devices may be used to convert thermal energy into electrical energy, or use electrical energy to produce heat or refrigeration. Embodiments of the invention relate to p-type thermoelectric materials related to the compound Yb.sub.14MnSb.sub.11.

Feasibility of large-scale power plants based on thermoelectric effects

NASA Astrophysics Data System (ADS)

Liu, Liping

2014-12-01

Heat resources of small temperature difference are easily accessible, free and enormous on the Earth. Thermoelectric effects provide the technology for converting these heat resources directly into electricity. We present designs for electricity generators based on thermoelectric effects that utilize heat resources of small temperature difference, e.g., ocean water at different depths and geothermal resources, and conclude that large-scale power plants based on thermoelectric effects are feasible and economically competitive. The key observation is that the power factor of thermoelectric materials, unlike the figure of merit, can be improved by orders of magnitude upon laminating good conductors and good thermoelectric materials. The predicted large-scale power generators based on thermoelectric effects, if validated, will have the advantages of the scalability, renewability, and free supply of heat resources of small temperature difference on the Earth.

Optimization of Heat Exchangers with Dimpled Surfaces to Improve the Performance in Thermoelectric Generators Using a Kriging Model

NASA Astrophysics Data System (ADS)

Li, Shuai; Wang, Yiping; Wang, Tao; Yang, Xue; Deng, Yadong; Su, Chuqi

2017-05-01

Thermoelectric generators (TEGs) have become a topic of interest for vehicle exhaust energy recovery. Electrical power generation is deeply influenced by temperature differences, temperature uniformity and topological structures of TEGs. When the dimpled surfaces are adopted in heat exchangers, the heat transfer rates can be augmented with a minimal pressure drop. However, the temperature distribution shows a large gradient along the flow direction which has adverse effects on the power generation. In the current study, the heat exchanger performance was studied in a computational fluid dynamics (CFD) model. The dimple depth, dimple print diameter, and channel height were chosen as design variables. The objective function was defined as a combination of average temperature, temperature uniformity and pressure loss. The optimal Latin hypercube method was used to determine the experiment points as a method of design of the experiment in order to analyze the sensitivity of the design variables. A Kriging surrogate model was built and verified according to the database resulting from the CFD simulation. A multi-island genetic algorithm was used to optimize the structure in the heat exchanger based on the surrogate model. The results showed that the average temperature of the heat exchanger was most sensitive to the dimple depth. The pressure loss and temperature uniformity were most sensitive to the parameter of channel rear height, h 2. With an optimal design of channel structure, the temperature uniformity can be greatly improved compared with the initial exchanger, and the additional pressure loss also increased.

Heat-Powered Pump for Liquid Metals

NASA Technical Reports Server (NTRS)

Campana, R. J.

1986-01-01

Proposed thermoelectromagnetic pump for liquid metal powered by waste heat; needs no battery, generator, or other external energy source. Pump turns part of heat in liquid metal into pumping energy. In combination with primary pump or on its own, thermoelectric pump circulates coolant between reactor and radiator. As long as there is decay heat to be removed, unit performs function.

Too Much of a Good Thing ? Radioisotope Power Conversion Technology and `Waste' Heat in the Titan Environment

NASA Astrophysics Data System (ADS)

Lorenz, Ralph

Unlike most solar system surface environments, Titan has an atmosphere that is both cold and dense. This means heat transfer to and from a vehicle is determined by convection, rather than by radiation which dominates on Earth and Mars. With surface temperatures near 94K, batteries and systems require heating to operate. Solar power is impractical, so a spacecraft intended to operate for longer than a few hours on Titan must have a radioisotope power source (RPS). Such sources convert heat from Plutonium decay into electricity, with an efficiency that varies from about 5% for thermoelectric systems to 20% for engine cycles such as Stirling. For vehicles with 100-200W electrical power, the 500-4000 W ‘waste’ heat in the Titan environment can be valuable in that it can be exploited to maintain thermal conditions inside the vehicle. The generally benign Titan environment, and the outstanding scientific and popular interest in its exploration, has attracted a number of mission concepts including a lander for Titan’s equatorial dunefields, light gas and hot air (‘Montgolfière’) balloons, airplanes, and capsules that float on its polar seas (e.g. the proposed Titan Mare Explorer.) However, the choice of conversion technology is key to the success of these different platforms. Waste heat can perturb meteorological measurements in several ways. First by creating a warm air plume (an effect observed on Viking and Curiosity.) Second, rain or seaspray falling onto hot radiator surfaces can evaporate causing a local enhancement of methane humidity. Third, sufficiently strong heating could perturb local winds. Similar effects, and the potential generation of effervescence or even fog, may result for capsules floating in liquid hydrocarbons. For landers and drifting buoys, these perturbations may significantly degrade environmental measurements, or at least demand tall meteorology masts, for the higher waste heat output of thermoelectric systems, and a Stirling system

Energy Optimization for a Weak Hybrid Power System of an Automobile Exhaust Thermoelectric Generator

NASA Astrophysics Data System (ADS)

Fang, Wei; Quan, Shuhai; Xie, Changjun; Tang, Xinfeng; Ran, Bin; Jiao, Yatian

2017-11-01

An integrated starter generator (ISG)-type hybrid electric vehicle (HEV) scheme is proposed based on the automobile exhaust thermoelectric generator (AETEG). An eddy current dynamometer is used to simulate the vehicle's dynamic cycle. A weak ISG hybrid bench test system is constructed to test the 48 V output from the power supply system, which is based on engine exhaust-based heat power generation. The thermoelectric power generation-based system must ultimately be tested when integrated into the ISG weak hybrid mixed power system. The test process is divided into two steps: comprehensive simulation and vehicle-based testing. The system's dynamic process is simulated for both conventional and thermoelectric powers, and the dynamic running process comprises four stages: starting, acceleration, cruising and braking. The quantity of fuel available and battery pack energy, which are used as target vehicle energy functions for comparison with conventional systems, are simplified into a single energy target function, and the battery pack's output current is used as the control variable in the thermoelectric hybrid energy optimization model. The system's optimal battery pack output current function is resolved when its dynamic operating process is considered as part of the hybrid thermoelectric power generation system. In the experiments, the system bench is tested using conventional power and hybrid thermoelectric power for the four dynamic operation stages. The optimal battery pack curve is calculated by functional analysis. In the vehicle, a power control unit is used to control the battery pack's output current and minimize energy consumption. Data analysis shows that the fuel economy of the hybrid power system under European Driving Cycle conditions is improved by 14.7% when compared with conventional systems.

Performance Analysis of a Thermoelectric Solar Collector Integrated with a Heat Pump

NASA Astrophysics Data System (ADS)

Lertsatitthanakorn, C.; Jamradloedluk, J.; Rungsiyopas, M.; Therdyothin, A.; Soponronnarit, S.

2013-07-01

A novel heat pump system is proposed. A thermoelectric solar collector was coupled to a solar-assisted heat pump (TESC-HP) to work as an evaporator. The cooling effect of the system's refrigerant allowed the cold side of the system's thermoelectric modules to work at lower temperature, improving the conversion efficiency. The TESC-HP system mainly consisted of transparent glass, an air gap, an absorber plate that acted as a direct expansion-type collector/evaporator, an R-134a piston-type hermetic compressor, a water-cooled plate-type condenser, thermoelectric modules, and a water storage tank. Test results indicated that the TESC-HP has better coefficient of performance (COP) and conversion efficiency than the separate units. For the meteorological conditions in Mahasarakham, the COP of the TESC-HP system can reach 5.48 when the average temperature of 100 L of water is increased from 28°C to 40°C in 60 min with average ambient temperature of 32.5°C and average solar intensity of 815 W/m2, whereas the conversion efficiency of the TE power generator was around 2.03%.

Multi-Scale Microstructural Thermoelectric Materials: Transport Behavior, Non-Equilibrium Preparation, and Applications.

PubMed

Su, Xianli; Wei, Ping; Li, Han; Liu, Wei; Yan, Yonggao; Li, Peng; Su, Chuqi; Xie, Changjun; Zhao, Wenyu; Zhai, Pengcheng; Zhang, Qingjie; Tang, Xinfeng; Uher, Ctirad

2017-05-01

Considering only about one third of the world's energy consumption is effectively utilized for functional uses, and the remaining is dissipated as waste heat, thermoelectric (TE) materials, which offer a direct and clean thermal-to-electric conversion pathway, have generated a tremendous worldwide interest. The last two decades have witnessed a remarkable development in TE materials. This Review summarizes the efforts devoted to the study of non-equilibrium synthesis of TE materials with multi-scale structures, their transport behavior, and areas of applications. Studies that work towards the ultimate goal of developing highly efficient TE materials possessing multi-scale architectures are highlighted, encompassing the optimization of TE performance via engineering the structures with different dimensional aspects spanning from the atomic and molecular scales, to nanometer sizes, and to the mesoscale. In consideration of the practical applications of high-performance TE materials, the non-equilibrium approaches offer a fast and controllable fabrication of multi-scale microstructures, and their scale up to industrial-size manufacturing is emphasized here. Finally, the design of two integrated power generating TE systems are described-a solar thermoelectric-photovoltaic hybrid system and a vehicle waste heat harvesting system-that represent perhaps the most important applications of thermoelectricity in the energy conversion area. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Wearable and flexible thermoelectric generator with enhanced package

NASA Astrophysics Data System (ADS)

Francioso, L.; De Pascali, C.; Taurino, A.; Siciliano, P.; De Risi, A.

2013-05-01

Present work shows recent progresses in thin film-based flexible and wearable thermoelectric generator (TEG), finalized to support energy scavenging and local storage for low consumption electronics in Ambient Assisted Living (AAL) applications and buildings integration. The proposed TEG is able to recover energy from heat dispersed into the environment converting a thermal gradient to an effective electrical energy available to power ultra-low consumption devices. A low cost fabrication process based on planar thin-film technology was optimized to scale down the TEG dimensions to micrometer range. The prototype integrates 2778 thermocouples of sputtered Sb2Te3 and Bi2Te3 thin films (1 μm thick) on an area of 25 cm2. The electrical properties of thermoelectric materials were investigated by Van der Pauw measurements. Transfer Length Method (TLM) analysis was performed on three different multi-layer contact schemes in order to select the best solution to use for the definition of the contact pads realized on each section of the thermoelectric array configuration to allow electrical testing of single production areas. Kapton polyimide film was used as flexible substrate in order to add comfortable lightweight and better wearability to the device. The realized TEG is able to autonomously recover the thermal gradient useful to thermoelectric generation thanks to an appropriate package designed and optimized by a thermal analysis based on finite element method (FEM). The proposed package solution consists in coupling the module realized onto Kapton foil to a PDMS layer opportunely molded to thermally insulate TEG cold junctions and enhance the thermal gradient useful for the energy scavenging. Simulations results were compared to experimental tests performed by a thermal infrared camera, in order to evaluate the real performance of the designed package. First tests conducted on the realized TEG indicate that the prototype is able to recover about 5°C between hot and

Fabrication and Characterization of CMOS-MEMS Thermoelectric Micro Generators

PubMed Central

Kao, Pin-Hsu; Shih, Po-Jen; Dai, Ching-Liang; Liu, Mao-Chen

2010-01-01

This work presents a thermoelectric micro generator fabricated by the commercial 0.35 μm complementary metal oxide semiconductor (CMOS) process and the post-CMOS process. The micro generator is composed of 24 thermocouples in series. Each thermocouple is constructed by p-type and n-type polysilicon strips. The output power of the generator depends on the temperature difference between the hot and cold parts in the thermocouples. In order to prevent heat-receiving in the cold part in the thermocouples, the cold part is covered with a silicon dioxide layer with low thermal conductivity to insulate the heat source. The hot part of the thermocouples is suspended and connected to an aluminum plate, to increases the heat-receiving area in the hot part. The generator requires a post-CMOS process to release the suspended structures. The post-CMOS process uses an anisotropic dry etching to remove the oxide sacrificial layer and an isotropic dry etching to etch the silicon substrate. Experimental results show that the micro generator has an output voltage of 67 μV at the temperature difference of 1 K. PMID:22205869

Size effect in thermoelectric materials

NASA Astrophysics Data System (ADS)

Mao, Jun; Liu, Zihang; Ren, Zhifeng

2016-12-01

Thermoelectric applications have attracted increasing interest recently due to its capability of converting waste heat into electricity without hazardous emissions. Materials with enhanced thermoelectric performance have been reported in recent two decades. The revival of research for thermoelectric materials began in early 1990s when the size effect is considered. Low-dimensional materials with exceptionally high thermoelectric figure of merit (ZT) have been presented, which broke the limit of ZT around unity. The idea of size effect in thermoelectric materials even inspired the later nanostructuring and band engineering strategies, which effectively enhanced the thermoelectric performance of bulk materials. In this overview, the size effect in low-dimensional thermoelectric materials is reviewed. We first discuss the quantum confinement effect on carriers, including the enhancement of electronic density of states, semimetal to semiconductor transition and carrier pocket engineering. Then, the effect of assumptions on theoretical calculations is presented. Finally, the effect of phonon confinement and interface scattering on lattice thermal conductivity is discussed.

Analysis of a Temperature-Controlled Exhaust Thermoelectric Generator During a Driving Cycle

NASA Astrophysics Data System (ADS)

Brito, F. P.; Alves, A.; Pires, J. M.; Martins, L. B.; Martins, J.; Oliveira, J.; Teixeira, J.; Goncalves, L. M.; Hall, M. J.

2016-03-01

Thermoelectric generators can be used in automotive exhaust energy recovery. As car engines operate under wide variable loads, it is a challenge to design a system for operating efficiently under these variable conditions. This means being able to avoid excessive thermal dilution under low engine loads and being able to operate under high load, high temperature events without the need to deflect the exhaust gases with bypass systems. The authors have previously proposed a thermoelectric generator (TEG) concept with temperature control based on the operating principle of the variable conductance heat pipe/thermosiphon. This strategy allows the TEG modules’ hot face to work under constant, optimized temperature. The variable engine load will only affect the number of modules exposed to the heat source, not the heat transfer temperature. This prevents module overheating under high engine loads and avoids thermal dilution under low engine loads. The present work assesses the merit of the aforementioned approach by analysing the generator output during driving cycles simulated with an energy model of a light vehicle. For the baseline evaporator and condenser configuration, the driving cycle averaged electrical power outputs were approximately 320 W and 550 W for the type-approval Worldwide harmonized light vehicles test procedure Class 3 driving cycle and for a real-world highway driving cycle, respectively.

Roll type conducting polymer legs for rigid-flexible thermoelectric generator

NASA Astrophysics Data System (ADS)

Park, Teahoon; Lim, Hanwhuy; Hwang, Jong Un; Na, Jongbeom; Lee, Hyunki; Kim, Eunkyoung

2017-07-01

A roll-type conducting polymer film was explored as a flexible organic p-type thermoelectric leg using poly(3,4-ethylenedioxythiophene) (PEDOT) doped with tosylate. The PEDOT films were prepared through solution casting polymerization and rolled up for a roll-type leg. Due to the high flexibility, the roll-type PEDOT leg enabled easy contact to both top and bottom electrodes. Simulation on the dynamic heat transfer and convective cooling for a vertically roosted rod- and roll-type PEDOT leg showed that the temperature difference (ΔT) between the hot and cold sides of the leg was much higher in the roll than that of the rod. The PEDOT legs were integrated with n-type Bi2Te3 blocks, to give a 36-couple rigid-flexible thermoelectric generator (RF-TEG). The maximum output voltage from the 36-couple RF-TEG under a ΔT of 7.9 K was determined as 36.7 mV along with a high output power of 115 nW. A wearable RF-TEG was prepared upon the combination of the 36-couple RF-TEG with an arm warmer, to afford an output voltage of 10.6 mV, which was generated constantly and steadily from human wrist heat.

Integration of Thermoelectric Generators and Wood Stove to Produce Heat, Hot Water, and Electrical Power

NASA Astrophysics Data System (ADS)

Goudarzi, A. M.; Mazandarani, P.; Panahi, R.; Behsaz, H.; Rezania, A.; Rosendahl, L. A.

2013-07-01

Traditional fire stoves are characterized by low efficiency. In this experimental study, the combustion chamber of the stove is augmented by two devices. An electric fan can increase the air-to-fuel ratio in order to increase the system's efficiency and decrease air pollution by providing complete combustion of wood. In addition, thermoelectric generators (TEGs) produce power that can be used to satisfy all basic needs. In this study, a water-based cooling system is designed to increase the efficiency of the TEGs and also produce hot water for residential use. Through a range of tests, an average of 7.9 W was achieved by a commercial TEG with substrate area of 56 mm × 56 mm, which can produce 14.7 W output power at the maximum matched load. The total power generated by the stove is 166 W. Also, in this study a reasonable ratio of fuel to time is described for residential use. The presented prototype is designed to fulfill the basic needs of domestic electricity, hot water, and essential heat for warming the room and cooking.

Flow Distribution Control Characteristics in Marine Gas Turbine Waste- Heat Recovery Systems. Phase 2. Flow Distribution Control in Waste-Heat Steam Generators

DTIC Science & Technology

1982-07-01

waste-heat steam generators. The applicable steam generator design concepts and general design consideration were reviewed and critical problems...a once-through forced-circulation steam generator design should be selected because of stability, reliability, compact- ness and lightweight...consists of three sections and one appendix. In Section I, the applicable steam generator design conccpts and general design * considerations are reviewed

Oligoyne Molecular Junctions for Efficient Room Temperature Thermoelectric Power Generation.

PubMed

Sadeghi, Hatef; Sangtarash, Sara; Lambert, Colin J

2015-11-11

Understanding phonon transport at a molecular scale is fundamental to the development of high-performance thermoelectric materials for the conversion of waste heat into electricity. We have studied phonon and electron transport in alkane and oligoyne chains of various lengths and find that, due to the more rigid nature of the latter, the phonon thermal conductances of oligoynes are counterintuitively lower than that of the corresponding alkanes. The thermal conductance of oligoynes decreases monotonically with increasing length, whereas the thermal conductance of alkanes initially increases with length and then decreases. This difference in behavior arises from phonon filtering by the gold electrodes and disappears when higher-Debye-frequency electrodes are used. Consequently a molecule that better transmits higher-frequency phonon modes, combined with a low-Debye-frequency electrode that filters high-energy phonons is a viable strategy for suppressing phonon transmission through the molecular junctions. The low thermal conductance of oligoynes, combined with their higher thermopower and higher electrical conductance lead to a maximum thermoelectric figure of merit of ZT = 1.4, which is several orders of magnitude higher than that of alkanes.

On the thermodynamics of waste heat recovery from internal combustion engine exhaust gas

NASA Astrophysics Data System (ADS)

Meisner, G. P.

2013-03-01

The ideal internal combustion (IC) engine (Otto Cycle) efficiency ηIC = 1-(1/r)(γ - 1) is only a function of engine compression ratio r =Vmax/Vmin and exhaust gas specific heat ratio γ = cP/cV. Typically r = 8, γ = 1.4, and ηIC = 56%. Unlike the Carnot Cycle where ηCarnot = 1-(TC/TH) for a heat engine operating between hot and cold heat reservoirs at TH and TC, respectively, ηIC is not a function of the exhaust gas temperature. Instead, the exhaust gas temperature depends only on the intake gas temperature (ambient), r, γ, cV, and the combustion energy. The ejected exhaust gas heat is thermally decoupled from the IC engine and conveyed via the exhaust system (manifold, pipe, muffler, etc.) to ambient, and the exhaust system is simply a heat engine that does no useful work. The maximum fraction of fuel energy that can be extracted from the exhaust gas stream as useful work is (1-ηIC) × ηCarnot = 32% for TH = 850 K (exhaust) and TC = 370 K (coolant). This waste heat can be recovered using a heat engine such as a thermoelectric generator (TEG) with ηTEG> 0 in the exhaust system. A combined IC engine and TEG system can generate net useful work from the exhaust gas waste heat with efficiency ηWH = (1-ηIC) × ηCarnot ×ηTEG , and this will increase the overall fuel efficiency of the total system. Recent improvements in TEGs yield ηTEG values approaching 15% giving a potential total waste heat conversion efficiency of ηWH = 4.6%, which translates into a fuel economy improvement approaching 5%. This work is supported by the US DOE under DE-EE0005432.

Modular Isotopic Thermoelectric Generator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schock, Alfred

1981-01-01

Advanced RTG concepts utilizing improved thermoelectric materials and converter concepts are under study at Fairchild for DOE. The design described here is based on DOE's newly developed radioisotope heat source, and on an improved silicon-germanium material and multicouple converter module under development at Syncal. Fairchild's assignment was to combine the above into an attractive power system for use in space, and to assess the specific power and other attributes of that design.

Evaluation of Thermoelectric Performance and Durability of Functionalized Skutterudite Legs

NASA Astrophysics Data System (ADS)

Skomedal, Gunstein; Kristiansen, Nils R.; Sottong, Reinhard; Middleton, Hugh

2017-04-01

Thermoelectric generators are a promising technology for waste heat recovery. As new materials and devices enter a market penetration stage, it is of interest to employ fast and efficient measurement methods to evaluate the long-term stability of thermoelectric materials in combination with metallization and coating (functionalized thermoelectric legs). We have investigated a method for measuring several thermoelectric legs simultaneously. The legs are put under a common temperature gradient, and the electrical characteristics of each leg are measured individually during thermal cycling. Using this method, one can test different types of metallization and coating applied to skutterudite thermoelectric legs and look at the relative changes over time. Postcharacterization of these initial tests with skutterudite legs using a potential Seebeck microprobe and an electron microscope showed that oxidation and interlayer diffusion are the main reasons for the gradual increase in internal resistance and the decrease in open-circuit voltage. Although we only tested skutterudite material in this work, the method is fully capable of testing all kinds of material, metallization, and coating. It is thus a promising method for studying the relationship between failure modes and mechanisms of functionalized thermoelectric legs.

Promising Thermoelectric Bulk Materials with 2D Structures.

PubMed

Zhou, Yiming; Zhao, Li-Dong

2017-12-01

Given that more than two thirds of all energy is lost, mostly as waste heat, in utilization processes worldwide, thermoelectric materials, which can directly convert waste heat to electricity, provide an alternative option for optimizing energy utilization processes. After the prediction that superlattices may show high thermoelectric performance, various methods based on quantum effects and superlattice theory have been adopted to analyze bulk materials, leading to the rapid development of thermoelectric materials. Bulk materials with two-dimensional (2D) structures show outstanding properties, and their high performance originates from both their low thermal conductivity and high Seebeck coefficient due to their strong anisotropic features. Here, the advantages of superlattices for enhancing the thermoelectric performance, the transport mechanism in bulk materials with 2D structures, and optimization methods are discussed. The phenomenological transport mechanism in these materials indicates that thermal conductivities are reduced in 2D materials with intrinsically short mean free paths. Recent progress in the transport mechanisms of Bi 2 Te 3 -, SnSe-, and BiCuSeO-based systems is summarized. Finally, possible research directions to enhance the thermoelectric performance of bulk materials with 2D structures are briefly considered. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Structural testing of the Los Alamos National Laboratory Heat Source/Radioisotopic Thermoelectric Generator shipping container

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bronowski, D.R.; Madsen, M.M.

The Heat Source/Radioisotopic Thermoelectric Generator shipping container is a Type B packaging design currently under development by Los Alamos National Laboratory. Type B packaging for transporting radioactive material is required to maintain containment and shielding after being exposed to the normal and hypothetical accident environments defined in Title 10 Code of Federal Regulations Part 71. A combination of testing and analysis is used to verify the adequacy of this package design. This report documents the test program portion of the design verification, using several prototype packages. Four types of testing were performed: 30-foot hypothetical accident condition drop tests in threemore » orientations, 40-inch hypothetical accident condition puncture tests in five orientations, a 21 psi external overpressure test, and a normal conditions of transport test consisting of a water spray and a 4 foot drop test. 18 refs., 104 figs., 13 tabs.« less

A Review on the Fabrication of Polymer-Based Thermoelectric Materials and Fabrication Methods

PubMed Central

Kamarudin, Muhammad Akmal; Sahamir, Shahrir Razey; Datta, Robi Shankar; Long, Bui Duc; Mohd Sabri, Mohd Faizul; Mohd Said, Suhana

2013-01-01

Thermoelectricity, by converting heat energy directly into useable electricity, offers a promising technology to convert heat from solar energy and to recover waste heat from industrial sectors and automobile exhausts. In recent years, most of the efforts have been done on improving the thermoelectric efficiency using different approaches, that is, nanostructuring, doping, molecular rattling, and nanocomposite formation. The applications of thermoelectric polymers at low temperatures, especially conducting polymers, have shown various advantages such as easy and low cost of fabrication, light weight, and flexibility. In this review, we will focus on exploring new types of polymers and the effects of different structures, concentrations, and molecular weight on thermoelectric properties. Various strategies to improve the performance of thermoelectric materials will be discussed. In addition, a discussion on the fabrication of thermoelectric devices, especially suited to polymers, will also be given. Finally, we provide the challenge and the future of thermoelectric polymers, especially thermoelectric hybrid model. PMID:24324378

Thermoelectric Devices Cool, Power Electronics

NASA Technical Reports Server (NTRS)

2009-01-01

Nextreme Thermal Solutions Inc., based in Research Triangle Park, North Carolina, licensed thermoelectric technology from NASA s Jet Propulsion Laboratory. This has allowed the company to develop cutting edge, thin-film thermoelectric coolers that effective remove heat generated by increasingly powerful and tightly packed microchip components. These solid-state coolers are ideal solutions for applications like microprocessors, laser diodes, LEDs, and even potentially for cooling the human body. Nextreme s NASA technology has also enabled the invention of thermoelectric generators capable of powering technologies like medical implants and wireless sensor networks.

Anisotropic Thermoelectric Devices Made from Single-Crystal Semimetal Microwires in Glass Coating

NASA Astrophysics Data System (ADS)

Konopko, L. A.; Nikolaeva, A. A.; Kobylianskaya, A. K.; Huber, T. E.

2018-06-01

Thermoelectric heat conversion based on the Seebeck and Peltier effects generated at the junction between two materials of type- n and type- p is well known. Here, we present a demonstration of an unconventional thermoelectric energy conversion that is based on a single element made of an anisotropic material. In such materials, a heat flow generates a transverse thermoelectric electric field lying across the heat flow. Potentially, in applications involving miniature devices, the anisotropic thermoelectric (AT) effect has the advantage over traditional thermoelectrics that it simplifies the thermoelectric generator architecture. This is because the generator can be made of a single thermoelectric material without the complexity of a series of contacts forming a pile. A feature of anisotropic thermoelectrics is that the thermoelectric voltage is proportional to the element length and inversely proportional to the effective thickness. The AT effect has been demonstrated with artificial anisotropic thin film consisting of layers of alternating thermoelectric type, but there has been no demonstration of this effect in a long single-crystal. Electronic transport measurements have shown that the semimetal bismuth is highly anisotropic. We have prepared an experimental sample consisting of a 10-m-long glass-insulated single-crystal tin-doped bismuth microwire ( d = 4 μm). Crucial for this experiment is the ability to grow the microwire as a single-crystal using a technique of recrystallization with laser heating and under a strong electric field. The sample was wound as a spiral, bonded to a copper disk, and used in various experiments. The sensitivity of the sample to heat flow is as high as 10-2 V/W with a time constant τ of about 0.5 s.

Anisotropic Thermoelectric Devices Made from Single-Crystal Semimetal Microwires in Glass Coating

NASA Astrophysics Data System (ADS)

Konopko, L. A.; Nikolaeva, A. A.; Kobylianskaya, A. K.; Huber, T. E.

2018-04-01

Thermoelectric heat conversion based on the Seebeck and Peltier effects generated at the junction between two materials of type-n and type-p is well known. Here, we present a demonstration of an unconventional thermoelectric energy conversion that is based on a single element made of an anisotropic material. In such materials, a heat flow generates a transverse thermoelectric electric field lying across the heat flow. Potentially, in applications involving miniature devices, the anisotropic thermoelectric (AT) effect has the advantage over traditional thermoelectrics that it simplifies the thermoelectric generator architecture. This is because the generator can be made of a single thermoelectric material without the complexity of a series of contacts forming a pile. A feature of anisotropic thermoelectrics is that the thermoelectric voltage is proportional to the element length and inversely proportional to the effective thickness. The AT effect has been demonstrated with artificial anisotropic thin film consisting of layers of alternating thermoelectric type, but there has been no demonstration of this effect in a long single-crystal. Electronic transport measurements have shown that the semimetal bismuth is highly anisotropic. We have prepared an experimental sample consisting of a 10-m-long glass-insulated single-crystal tin-doped bismuth microwire (d = 4 μm). Crucial for this experiment is the ability to grow the microwire as a single-crystal using a technique of recrystallization with laser heating and under a strong electric field. The sample was wound as a spiral, bonded to a copper disk, and used in various experiments. The sensitivity of the sample to heat flow is as high as 10-2 V/W with a time constant τ of about 0.5 s.

Solution-Processed Cu2Se Nanocrystal Films with Bulk-Like Thermoelectric Performance.

PubMed

Forster, Jason D; Lynch, Jared J; Coates, Nelson E; Liu, Jun; Jang, Hyejin; Zaia, Edmond; Gordon, Madeleine P; Szybowski, Maxime; Sahu, Ayaskanta; Cahill, David G; Urban, Jeffrey J

2017-06-05

Thermoelectric power generation can play a key role in a sustainable energy future by converting waste heat from power plants and other industrial processes into usable electrical power. Current thermoelectric devices, however, require energy intensive manufacturing processes such as alloying and spark plasma sintering. Here, we describe the fabrication of a p-type thermoelectric material, copper selenide (Cu 2 Se), utilizing solution-processing and thermal annealing to produce a thin film that achieves a figure of merit, ZT, which is as high as its traditionally processed counterpart, a value of 0.14 at room temperature. This is the first report of a fully solution-processed nanomaterial achieving performance equivalent to its bulk form and represents a general strategy to reduce the energy required to manufacture advanced energy conversion and harvesting materials.

Anisotropic thermoelectric behavior in armchair and zigzag mono- and fewlayer MoS2 in thermoelectric generator applications

PubMed Central

Arab, Abbas; Li, Qiliang

2015-01-01

In this work, we have studied thermoelectric properties of monolayer and fewlayer MoS2 in both armchair and zigzag orientations. Density functional theory (DFT) using non-equilibrium Green’s function (NEGF) method has been implemented to calculate the transmission spectra of mono- and fewlayer MoS2 in armchair and zigzag directions. Phonon transmission spectra are calculated based on parameterization of Stillinger-Weber potential. Thermoelectric figure of merit, ZT, is calculated using these electronic and phonon transmission spectra. In general, a thermoelectric generator is composed of thermocouples made of both n-type and p-type legs. Based on our calculations, monolayer MoS2 in armchair orientation is found to have the highest ZT value for both p-type and n-type legs compared to all other armchair and zigzag structures. We have proposed a thermoelectric generator based on monolayer MoS2 in armchair orientation. Moreover, we have studied the effect of various dopant species on thermoelectric current of our proposed generator. Further, we have compared output current of our proposed generator with those of Silicon thin films. Results indicate that thermoelectric current of MoS2 armchair monolayer is several orders of magnitude higher than that of Silicon thin films. PMID:26333948

Anisotropic thermoelectric behavior in armchair and zigzag mono- and fewlayer MoS2 in thermoelectric generator applications.

PubMed

Arab, Abbas; Li, Qiliang

2015-09-03

In this work, we have studied thermoelectric properties of monolayer and fewlayer MoS2 in both armchair and zigzag orientations. Density functional theory (DFT) using non-equilibrium Green's function (NEGF) method has been implemented to calculate the transmission spectra of mono- and fewlayer MoS2 in armchair and zigzag directions. Phonon transmission spectra are calculated based on parameterization of Stillinger-Weber potential. Thermoelectric figure of merit, ZT, is calculated using these electronic and phonon transmission spectra. In general, a thermoelectric generator is composed of thermocouples made of both n-type and p-type legs. Based on our calculations, monolayer MoS2 in armchair orientation is found to have the highest ZT value for both p-type and n-type legs compared to all other armchair and zigzag structures. We have proposed a thermoelectric generator based on monolayer MoS2 in armchair orientation. Moreover, we have studied the effect of various dopant species on thermoelectric current of our proposed generator. Further, we have compared output current of our proposed generator with those of Silicon thin films. Results indicate that thermoelectric current of MoS2 armchair monolayer is several orders of magnitude higher than that of Silicon thin films.

Heat radiation approach for harnessing heat of the cook stove to generate electricity for lighting system and charging of mobile phone

NASA Astrophysics Data System (ADS)

Muñoz, Rodrigo C., Jr.; Manansala, Chad Deo G.

2018-01-01

This study is based on the potential of thermoelectric coupling such as the thermoelectric cooler module. A thermoelectric cooler converts the heat coming from the cook stove into electricity and store in a battery. A dc-dc boost converter will be used to produce enough voltage to light a minimum house dwelling or charge phone battery. This device will be helpful to those that faces a problem on electricity especially in the isolated areas. The study aims (1) to harness heat from the cook stove up to 110 °C (2) To automatically cool-off the system to protect the thermoelectric cooler from damage due to excessive heat using an electronic solenoid; (3) To store energy harnessed in the battery; (4) To amplify the output voltages of the battery using DC to DC boost converter for lighting system and charging of mobile phone battery. From various tests conducted, it can fully charge a mobile phone in 3 hours observing the unit’s battery voltage drop from 4.06V to 3.98V. In the testing it used different orientation of steel rod by conduction to transfer heat and by radiation through tubular steel with its different dimensions. Most recent testing proved that the 2x2x9 tubular steel by radiation had the best result. The temperature reached more than a hundred degree Celsius that met the objective. The test resulted of boosting the voltage of the battery output from 3.7V to 4.96V on the average. The boosted voltage decrease as the system’s cool-off mechanism operated when the temperature reached above 110 degree Celsius decreasing output voltage to 0.8V resulting the boosted voltage to drop to zero. Therefore, the proponents concluded that heat waste can be converted to electrical energy by harnessing heat through radiation, with the help of TEC that generates voltage for lighting and can be boosted to be used for mobile charging. Furthermore, the study proved that the excess heat can damaged the TEC which was prevented by using of cooling-off mechanism, making it more

High-performance flat-panel solar thermoelectric generators with high thermal concentration.

PubMed

Kraemer, Daniel; Poudel, Bed; Feng, Hsien-Ping; Caylor, J Christopher; Yu, Bo; Yan, Xiao; Ma, Yi; Wang, Xiaowei; Wang, Dezhi; Muto, Andrew; McEnaney, Kenneth; Chiesa, Matteo; Ren, Zhifeng; Chen, Gang

2011-05-01

The conversion of sunlight into electricity has been dominated by photovoltaic and solar thermal power generation. Photovoltaic cells are deployed widely, mostly as flat panels, whereas solar thermal electricity generation relying on optical concentrators and mechanical heat engines is only seen in large-scale power plants. Here we demonstrate a promising flat-panel solar thermal to electric power conversion technology based on the Seebeck effect and high thermal concentration, thus enabling wider applications. The developed solar thermoelectric generators (STEGs) achieved a peak efficiency of 4.6% under AM1.5G (1 kW m(-2)) conditions. The efficiency is 7-8 times higher than the previously reported best value for a flat-panel STEG, and is enabled by the use of high-performance nanostructured thermoelectric materials and spectrally-selective solar absorbers in an innovative design that exploits high thermal concentration in an evacuated environment. Our work opens up a promising new approach which has the potential to achieve cost-effective conversion of solar energy into electricity. © 2011 Macmillan Publishers Limited. All rights reserved

High-performance flat-panel solar thermoelectric generators with high thermal concentration

NASA Astrophysics Data System (ADS)

Kraemer, Daniel; Poudel, Bed; Feng, Hsien-Ping; Caylor, J. Christopher; Yu, Bo; Yan, Xiao; Ma, Yi; Wang, Xiaowei; Wang, Dezhi; Muto, Andrew; McEnaney, Kenneth; Chiesa, Matteo; Ren, Zhifeng; Chen, Gang

2011-07-01

The conversion of sunlight into electricity has been dominated by photovoltaic and solar thermal power generation. Photovoltaic cells are deployed widely, mostly as flat panels, whereas solar thermal electricity generation relying on optical concentrators and mechanical heat engines is only seen in large-scale power plants. Here we demonstrate a promising flat-panel solar thermal to electric power conversion technology based on the Seebeck effect and high thermal concentration, thus enabling wider applications. The developed solar thermoelectric generators (STEGs) achieved a peak efficiency of 4.6% under AM1.5G (1 kW m-2) conditions. The efficiency is 7-8 times higher than the previously reported best value for a flat-panel STEG, and is enabled by the use of high-performance nanostructured thermoelectric materials and spectrally-selective solar absorbers in an innovative design that exploits high thermal concentration in an evacuated environment. Our work opens up a promising new approach which has the potential to achieve cost-effective conversion of solar energy into electricity.

Bulk dimensional nanocomposites for thermoelectric applications

DOEpatents

Nolas, George S

2014-06-24

Thermoelectric elements may be used for heat sensors, heat pumps, and thermoelectric generators. A quantum-dot or nano-scale grain size polycrystalline material the effects of size-quantization are present inside the nanocrystals. A thermoelectric element composed of densified Groups IV-VI material, such as calcogenide-based materials are doped with metal or chalcogenide to form interference barriers form along grains. The dopant used is either silver or sodium. These chalcogenide materials form nanoparticles of highly crystal grains, and may specifically be between 1- and 100 nm. The compound is densified by spark plasma sintering.

Fabrication of Advanced Thermoelectric Materials by Hierarchical Nanovoid Generation

NASA Technical Reports Server (NTRS)

Park, Yeonjoon (Inventor); Elliott, James R. (Inventor); Stoakley, Diane M. (Inventor); Chu, Sang-Hyon (Inventor); King, Glen C. (Inventor); Kim, Jae-Woo (Inventor); Choi, Sang Hyouk (Inventor); Lillehei, Peter T. (Inventor)

2011-01-01

A novel method to prepare an advanced thermoelectric material has hierarchical structures embedded with nanometer-sized voids which are key to enhancement of the thermoelectric performance. Solution-based thin film deposition technique enables preparation of stable film of thermoelectric material and void generator (voigen). A subsequent thermal process creates hierarchical nanovoid structure inside the thermoelectric material. Potential application areas of this advanced thermoelectric material with nanovoid structure are commercial applications (electronics cooling), medical and scientific applications (biological analysis device, medical imaging systems), telecommunications, and defense and military applications (night vision equipments).

Convergence of electronic bands for high performance bulk thermoelectrics.

PubMed

Pei, Yanzhong; Shi, Xiaoya; LaLonde, Aaron; Wang, Heng; Chen, Lidong; Snyder, G Jeffrey

2011-05-05

Thermoelectric generators, which directly convert heat into electricity, have long been relegated to use in space-based or other niche applications, but are now being actively considered for a variety of practical waste heat recovery systems-such as the conversion of car exhaust heat into electricity. Although these devices can be very reliable and compact, the thermoelectric materials themselves are relatively inefficient: to facilitate widespread application, it will be desirable to identify or develop materials that have an intensive thermoelectric materials figure of merit, zT, above 1.5 (ref. 1). Many different concepts have been used in the search for new materials with high thermoelectric efficiency, such as the use of nanostructuring to reduce phonon thermal conductivity, which has led to the investigation of a variety of complex material systems. In this vein, it is well known that a high valley degeneracy (typically ≤6 for known thermoelectrics) in the electronic bands is conducive to high zT, and this in turn has stimulated attempts to engineer such degeneracy by adopting low-dimensional nanostructures. Here we demonstrate that it is possible to direct the convergence of many valleys in a bulk material by tuning the doping and composition. By this route, we achieve a convergence of at least 12 valleys in doped PbTe(1-x)Se(x) alloys, leading to an extraordinary zT value of 1.8 at about 850 kelvin. Band engineering to converge the valence (or conduction) bands to achieve high valley degeneracy should be a general strategy in the search for and improvement of bulk thermoelectric materials, because it simultaneously leads to a high Seebeck coefficient and high electrical conductivity. ©2011 Macmillan Publishers Limited. All rights reserved

Optimization of power generating thermoelectric modules utilizing LNG cold energy

NASA Astrophysics Data System (ADS)

Jeong, Eun Soo

2017-12-01

A theoretical investigation to optimize thermoelectric modules, which convert LNG cold energy into electrical power, is performed using a novel one-dimensional analytic model. In the model the optimum thermoelement length and external load resistance, which maximize the energy conversion ratio, are determined by the heat supplied to the cold heat reservoir, the hot and cold side temperatures, the thermal and electrical contact resistances and the properties of thermoelectric materials. The effects of the thermal and electrical contact resistances and the heat supplied to the cold heat reservoir on the maximum energy conversion ratio, the optimum thermoelement length and the optimum external load resistance are shown.

Car companies look to generate power from waste heat

NASA Astrophysics Data System (ADS)

Schirber, Michael

2008-04-01

You might think that the steam engine is an outdated technology that had its heyday centuries ago, but in fact steam is once again a hot topic with vehicle manufacturers. Indeed, the next generation of hybrid cars and trucks may incorporate some form of steam power. Honda, for example, has just released details of a new prototype hybrid car that recharges its battery using a steam engine that exploits waste heat from the exhaust pipe.

Realizing high figure of merit in heavy-band p-type half-Heusler thermoelectric materials.

PubMed

Fu, Chenguang; Bai, Shengqiang; Liu, Yintu; Tang, Yunshan; Chen, Lidong; Zhao, Xinbing; Zhu, Tiejun

2015-09-02

Solid-state thermoelectric technology offers a promising solution for converting waste heat to useful electrical power. Both high operating temperature and high figure of merit zT are desirable for high-efficiency thermoelectric power generation. Here we report a high zT of ∼1.5 at 1,200 K for the p-type FeNbSb heavy-band half-Heusler alloys. High content of heavier Hf dopant simultaneously optimizes the electrical power factor and suppresses thermal conductivity. Both the enhanced point-defect and electron-phonon scatterings contribute to a significant reduction in the lattice thermal conductivity. An eight couple prototype thermoelectric module exhibits a high conversion efficiency of 6.2% and a high power density of 2.2 W cm(-2) at a temperature difference of 655 K. These findings highlight the optimization strategy for heavy-band thermoelectric materials and demonstrate a realistic prospect of high-temperature thermoelectric modules based on half-Heusler alloys with low cost, excellent mechanical robustness and stability.

Ionic Liquids for Utilization of Waste Heat from Distributed Power Generation Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Joan F. Brennecke; Mihir Sen; Edward J. Maginn

2009-01-11

The objective of this research project was the development of ionic liquids to capture and utilize waste heat from distributed power generation systems. Ionic Liquids (ILs) are organic salts that are liquid at room temperature and they have the potential to make fundamental and far-reaching changes in the way we use energy. In particular, the focus of this project was fundamental research on the potential use of IL/CO2 mixtures in absorption-refrigeration systems. Such systems can provide cooling by utilizing waste heat from various sources, including distributed power generation. The basic objectives of the research were to design and synthesize ILsmore » appropriate for the task, to measure and model thermophysical properties and phase behavior of ILs and IL/CO2 mixtures, and to model the performance of IL/CO2 absorption-refrigeration systems.« less

About the feasibilities of controlling the properties of thermoelectric energy converters using optical radiation

NASA Astrophysics Data System (ADS)

Kshevetsky, Oleg S.

2018-01-01

We represent evaluating analysis of the feasibilities for controlling the properties of thermoelectric energy converters using EM radiation in the regimes of cooling, heating, electromotive force generation, or electric current generation. Thus we investigate the influence of optical radiation both on electric conductivity and thermo-electromotive force coefficient of thermoelectric materials. We also discuss promising applications for controlling the properties of thermoelectric energy converters using EM radiation. We represent the results of experimental study of positionsensitive energy converters in the regimes of electromotive force generation and the electric current generation (in part, photo-thermoelectric position-sensitive temperature detectors), position-sensitive photo-thermoelectric energy converters in the regimes of cooling, heating, parallel photoelectric and thermoelectric conversion of sun-light optical radiation into electric power.

Opto-thermoelectric nanotweezers

NASA Astrophysics Data System (ADS)

Lin, Linhan; Wang, Mingsong; Peng, Xiaolei; Lissek, Emanuel N.; Mao, Zhangming; Scarabelli, Leonardo; Adkins, Emily; Coskun, Sahin; Unalan, Husnu Emrah; Korgel, Brian A.; Liz-Marzán, Luis M.; Florin, Ernst-Ludwig; Zheng, Yuebing

2018-04-01

Optical manipulation of plasmonic nanoparticles provides opportunities for fundamental and technical innovation in nanophotonics. Optical heating arising from the photon-to-phonon conversion is considered as an intrinsic loss in metal nanoparticles, which limits their applications. We show here that this drawback can be turned into an advantage, by developing an extremely low-power optical tweezing technique, termed opto-thermoelectric nanotweezers. By optically heating a thermoplasmonic substrate, a light-directed thermoelectric field can be generated due to spatial separation of dissolved ions within the heating laser spot, which allows us to manipulate metal nanoparticles of a wide range of materials, sizes and shapes with single-particle resolution. In combination with dark-field optical imaging, nanoparticles can be selectively trapped and their spectroscopic response can be resolved in situ. With its simple optics, versatile low-power operation, applicability to diverse nanoparticles and tunable working wavelength, opto-thermoelectric nanotweezers will become a powerful tool in colloid science and nanotechnology.

Design and construction of Thermoelectric Footwear Heating System for illness feet.

PubMed

Işik, Hakan

2005-12-01

In this study, a Thermoelectric Footwear Heating System is developed to use in cold weather conditions. The temperature is controlled by an analog electronic control system. Thermoelectric module is used to heat the bottom of the foot. A negative temperature coefficient (NTC) temperature sensor is used to sense the temperature and the temperature is controlled by an electronic circuit proportionally. A 3.5 V, 5000 mAh rechargeable battery is used as the power source. The temperature range of the system is between +15 degrees C and +50 degrees C. Developed footwear heating system is tested against various temperature conditions, and offer better results in the case of heating the illness feet.

Optimal Design of a Thermoelectric Cooling/Heating System for Car Seat Climate Control (CSCC)

NASA Astrophysics Data System (ADS)

Elarusi, Abdulmunaem; Attar, Alaa; Lee, Hosung

2017-04-01

In the present work, the optimum design of thermoelectric car seat climate control (CSCC) is studied analytically in an attempt to achieve high system efficiency. Optimal design of a thermoelectric device (element length, cross-section area and number of thermocouples) is carried out using our newly developed optimization method based on the ideal thermoelectric equations and dimensional analysis to improve the performance of the thermoelectric device in terms of the heating/cooling power and the coefficient of performance (COP). Then, a new innovative system design is introduced which also includes the optimum input current for the initial (transient) startup warming and cooling before the car heating ventilation and air conditioner (HVAC) is active in the cabin. The air-to-air heat exchanger's configuration was taken into account to investigate the optimal design of the CSCC.

Nanostructured Bulk Thermoelectric Generator for Efficient Power Harvesting for Self-powered Sensor Networks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Yanliang; Butt, Darryl; Agarwal, Vivek

2015-07-01

The objective of this Nuclear Energy Enabling Technology research project is to develop high-efficiency and reliable thermoelectric generators for self-powered wireless sensors nodes utilizing thermal energy from nuclear plant or fuel cycle. The power harvesting technology has crosscutting significance to address critical technology gaps in monitoring nuclear plants and fuel cycle. The outcomes of the project will lead to significant advancement in sensors and instrumentation technology, reducing cost, improving monitoring reliability and therefore enhancing safety. The self-powered wireless sensor networks could support the long-term safe and economical operation of all the reactor designs and fuel cycle concepts, as well asmore » spent fuel storage and many other nuclear science and engineering applications. The research is based on recent breakthroughs in high-performance nanostructured bulk (nanobulk) thermoelectric materials that enable high-efficiency direct heat-to-electricity conversion over a wide temperature range. The nanobulk thermoelectric materials that the research team at Boise State University and University of Houston has developed yield up to a 50% increase in the thermoelectric figure of merit, ZT, compared with state-of-the-art bulk counterparts. This report focuses on the selection of optimal thermoelectric materials for this project. The team has performed extensive study on two thermoelectric materials systems, i.e. the half-Heusler materials, and the Bismuth-Telluride materials. The report contains our recent research results on the fabrication, characterization and thermoelectric property measurements of these two materials.« less

Facile Preparation of Highly Conductive Metal Oxides by Self-Combustion for Solution-Processed Thermoelectric Generators.

PubMed

Kang, Young Hun; Jang, Kwang-Suk; Lee, Changjin; Cho, Song Yun

2016-03-02

Highly conductive indium zinc oxide (IZO) thin films were successfully fabricated via a self-combustion reaction for application in solution-processed thermoelectric devices. Self-combustion efficiently facilitates the conversion of soluble precursors into metal oxides by lowering the required annealing temperature of oxide films, which leads to considerable enhancement of the electrical conductivity of IZO thin films. Such enhanced electrical conductivity induced by exothermic heat from a combustion reaction consequently yields high performance IZO thermoelectric films. In addition, the effect of the composition ratio of In to Zn precursors on the electrical and thermoelectric properties of the IZO thin films was investigated. IZO thin films with a composition ratio of In:Zn = 6:2 at the low annealing temperature of 350 °C showed an enhanced electrical conductivity, Seebeck coefficient, and power factor of 327 S cm(-1), 50.6 μV K(-1), and 83.8 μW m(-1) K(-2), respectively. Moreover, the IZO thin film prepared at an even lower temperature of 300 °C retained a large power factor of 78.7 μW m(-1) K(-2) with an electrical conductivity of 168 S cm(-1). Using the combustive IZO precursor, a thermoelectric generator consisting of 15 legs was fabricated by a printing process. The thermoelectric array generated a thermoelectric voltage of 4.95 mV at a low temperature difference (5 °C). We suggest that the highly conductive IZO thin films by self-combustion may be utilized for fabricating n-type flexible printed thermoelectric devices.

Solution-Processed Cu 2Se Nanocrystal Films with Bulk-Like Thermoelectric Performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Forster, Jason D.; Lynch, Jared J.; Coates, Nelson E.

Thermoelectric power generation can play a key role in a sustainable energy future by converting waste heat from power plants and other industrial processes into usable electrical power. Current thermoelectric devices, however, require energy intensive manufacturing processes such as alloying and spark plasma sintering. Here, we describe the fabrication of a p-type thermoelectric material, copper selenide (Cu 2 Se), utilizing solution-processing and thermal annealing to produce a thin film that achieves a figure of merit, ZT, which is as high as its traditionally processed counterpart, a value of 0.14 at room temperature. This is the first report of amore » fully solution-processed nanomaterial achieving performance equivalent to its bulk form and represents a general strategy to reduce the energy required to manufacture advanced energy conversion and harvesting materials.« less

Solution-Processed Cu 2Se Nanocrystal Films with Bulk-Like Thermoelectric Performance

DOE PAGES

Forster, Jason D.; Lynch, Jared J.; Coates, Nelson E.; ...

2017-06-05

Thermoelectric power generation can play a key role in a sustainable energy future by converting waste heat from power plants and other industrial processes into usable electrical power. Current thermoelectric devices, however, require energy intensive manufacturing processes such as alloying and spark plasma sintering. Here, we describe the fabrication of a p-type thermoelectric material, copper selenide (Cu 2 Se), utilizing solution-processing and thermal annealing to produce a thin film that achieves a figure of merit, ZT, which is as high as its traditionally processed counterpart, a value of 0.14 at room temperature. This is the first report of amore » fully solution-processed nanomaterial achieving performance equivalent to its bulk form and represents a general strategy to reduce the energy required to manufacture advanced energy conversion and harvesting materials.« less

Quantity, Quality, and Availability of Waste Heat from United States Thermal Power Generation.

PubMed

Gingerich, Daniel B; Mauter, Meagan S

2015-07-21

Secondary application of unconverted heat produced during electric power generation has the potential to improve the life-cycle fuel efficiency of the electric power industry and the sectors it serves. This work quantifies the residual heat (also known as waste heat) generated by U.S. thermal power plants and assesses the intermittency and transport issues that must be considered when planning to utilize this heat. Combining Energy Information Administration plant-level data with literature-reported process efficiency data, we develop estimates of the unconverted heat flux from individual U.S. thermal power plants in 2012. Together these power plants discharged an estimated 18.9 billion GJ(th) of residual heat in 2012, 4% of which was discharged at temperatures greater than 90 °C. We also characterize the temperature, spatial distribution, and temporal availability of this residual heat at the plant level and model the implications for the technical and economic feasibility of its end use. Increased implementation of flue gas desulfurization technologies at coal-fired facilities and the higher quality heat generated in the exhaust of natural gas fuel cycles are expected to increase the availability of residual heat generated by 10.6% in 2040.

Analysis and Experimental Investigation of Optimum Design of Thermoelectric Cooling/Heating System for Car Seat Climate Control (CSCC)

NASA Astrophysics Data System (ADS)

Elarusi, Abdulmunaem; Attar, Alaa; Lee, HoSung

2018-02-01

The optimum design of a thermoelectric system for application in car seat climate control has been modeled and its performance evaluated experimentally. The optimum design of the thermoelectric device combining two heat exchangers was obtained by using a newly developed optimization method based on the dimensional technique. Based on the analytical optimum design results, commercial thermoelectric cooler and heat sinks were selected to design and construct the climate control heat pump. This work focuses on testing the system performance in both cooling and heating modes to ensure accurate analytical modeling. Although the analytical performance was calculated using the simple ideal thermoelectric equations with effective thermoelectric material properties, it showed very good agreement with experiment for most operating conditions.

Waste heat utilization in industrial processes

NASA Technical Reports Server (NTRS)

Weichsel, M.; Heitmann, W.

1978-01-01

A survey is given of new developments in heat exchangers and heat pumps. With respect to practical applications, internal criteria for plant operation are discussed. Possibilities of government support are pointed out. Waste heat steam generators and waste heat aggregates for hot water generation or in some cases for steam superheating are used. The possibilities of utilization can be classified according to the economic improvements and according to their process applications, for example, gascooling. Examples are presented for a large variety of applications.

Thermoelectric generator and method for the fabrication thereof

DOEpatents

Benson, David K.; Tracy, C. Edwin

1987-01-01

A thermoelectric generator using semiconductor elements for responding to a temperature gradient to produce electrical energy with all of the semiconductor elements being of the same type is disclosed. A continuous process for forming substrates on which the semiconductor elements and superstrates are deposited and a process for forming the semiconductor elements on the substrates are also disclosed. The substrates with the semiconductor elements thereon are combined with superstrates to form modules for use thermoelectric generators.

Thermoelectric generator and method for the fabrication thereof

DOEpatents

Benson, D.K.; Tracy, C.E.

1984-08-01

A thermoelectric generator using semiconductor elements for responding to a temperature gradient to produce electrical energy with all of the semiconductor elements being of the same type is disclosed. A continuous process for forming substrates on which the semiconductor elements and superstrates are deposited and a process for forming the semiconductor elements on the substrates are also disclosed. The substrates with the semiconductor elements thereon are combined with superstrates to form modules for use as thermoelectric generators.

Methods of synthesizing thermoelectric materials

DOEpatents

Ren, Zhifeng; Chen, Shuo; Liu, Wei-Shu; Wang, Hengzhi; Wang, Hui; Yu, Bo; Chen, Gang

2016-04-05

Methods for synthesis of thermoelectric materials are disclosed. In some embodiments, a method of fabricating a thermoelectric material includes generating a plurality of nanoparticles from a starting material comprising one or more chalcogens and one or more transition metals; and consolidating the nanoparticles under elevated pressure and temperature, wherein the nanoparticles are heated and cooled at a controlled rate.

Performance Model and Sensitivity Analysis for a Solar Thermoelectric Generator

NASA Astrophysics Data System (ADS)

Rehman, Naveed Ur; Siddiqui, Mubashir Ali

2017-03-01

In this paper, a regression model for evaluating the performance of solar concentrated thermoelectric generators (SCTEGs) is established and the significance of contributing parameters is discussed in detail. The model is based on several natural, design and operational parameters of the system, including the thermoelectric generator (TEG) module and its intrinsic material properties, the connected electrical load, concentrator attributes, heat transfer coefficients, solar flux, and ambient temperature. The model is developed by fitting a response curve, using the least-squares method, to the results. The sample points for the model were obtained by simulating a thermodynamic model, also developed in this paper, over a range of values of input variables. These samples were generated employing the Latin hypercube sampling (LHS) technique using a realistic distribution of parameters. The coefficient of determination was found to be 99.2%. The proposed model is validated by comparing the predicted results with those in the published literature. In addition, based on the elasticity for parameters in the model, sensitivity analysis was performed and the effects of parameters on the performance of SCTEGs are discussed in detail. This research will contribute to the design and performance evaluation of any SCTEG system for a variety of applications.

Machine-Thermal Coupling Stresses Analysis of the Fin-Type Structural Thermoelectric Generator

NASA Astrophysics Data System (ADS)

Zhang, Zheng; Yue, Hao; Chen, Dongbo; Qin, Delei; Chen, Zijian

2017-05-01

The design structure and heat-transfer mechanism of a thermoelectric generator (TEG) determine its body temperature state. Thermal stress and thermal deformation generated by the temperature variation directly affect the stress state of thermoelectric modules (TEMs). Therefore, the rated temperature and pressing force of TEMs are important parameters in TEG design. Here, the relationships between structural of a fin-type TEG (FTEG) and these parameters are studied by modeling and "machine-thermal" coupling simulation. An indirect calculation method is adopted in the coupling simulation. First, numerical heat transfer calculations of a three-dimensional FTEG model are conducted according to an orthogonal simulation table. The influences of structural parameters for heat transfer in the channel and outer fin temperature distribution are analyzed. The optimal structural parameters are obtained and used to simulate temperature field of the outer fins. Second, taking the thermal calculation results as the initial condition, the thermal-solid coupling calculation is adopted. The thermal stresses of outer fin, mechanical force of spring-angle pressing mechanism, and clamping force on a TEM are analyzed. The simulation results show that the heat transfer area of the inner fin and the physical parameters of the metal materials are the keys to determining the FTEG temperature field. The pressing mechanism's mechanical force can be reduced by reducing the outer fin angle. In addition, a corrugated cooling water pipe, which has cooling and spring functionality, is conducive to establishing an adaptable clamping force to avoid the TEMs being crushed by the thermal stresses in the body.

Synthesis and Characterization of Thermoelectric Oxides at Macro- and Nano-scales

NASA Astrophysics Data System (ADS)

Ma, Feiyue

Thermoelectric materials can directly convert a temperature difference into electrical voltage and vice versa. Due to this unique property, thermoelectric materials are widely used in industry and scientific laboratories for temperature sensing and thermal management applications. Waste heat harvesting, another potential application of thermoelectric materials, has long been limited by the low conversion efficiency of the materials. Potential high temperature applications, such as power plant waste heat harvesting and combustion engine exhaust heat recovery, make thermoelectric oxides a very promising class of thermoelectric materials. In this thesis, the synthesis and characterization of thermoelectric oxide materials are explored. In the first part of this thesis, the measurement methodologies and instrumentation processes employed to investigate different thermoelectric properties, such as the Seebeck coefficient and carrier concentration at the bulk scale and the thermal conductivity at the nanoscale, are detailed. Existing scientific and engineering challenges associated with these measurements are also reviewed. To overcome such problems, original parts and methodologies have been designed. Three fully functional systems were ultimately developed for the characterization of macroscale thermoelectric properties as well as localized thermal conductivity. In the second part of the thesis, the synthesis of NaxCo 2O4, a thermoelectric oxide material, is discussed. Modification of both composition and structure were carried out so as to optimize the thermoelectric performance of NaxCo2O4. Nanostructuring methods, such as ball milling, electrospinning, auto-combustion synthesis, and core-shell structure fabrication, have been developed to refine the grain size of NaxCo2O4 in order to reduce its thermal conductivity. However, the structure of the nanostructured materials is very unstable at high temperature and limited improvement on thermoelectric performance is

Transient thermoelectric supercooling: Isosceles current pulses from a response surface perspective and the performance effects of pulse cooling a heat generating mass

NASA Astrophysics Data System (ADS)

Piggott, Alfred J., III

With increased public interest in protecting the environment, scientists and engineers aim to improve energy conversion efficiency. Thermoelectrics offer many advantages as thermal management technology. When compared to vapor compression refrigeration, above approximately 200 to 600 watts, cost in dollars per watt as well as COP are not advantageous for thermoelectrics. The goal of this work was to determine if optimized pulse supercooling operation could improve cooling capacity or efficiency of a thermoelectric device. The basis of this research is a thermal-electrical analogy based modeling study using SPICE. Two models were developed. The first model, a standalone thermocouple with no attached mass to be cooled. The second, a system that includes a module attached to a heat generating mass. With the thermocouple study, a new approach of generating response surfaces with characteristic parameters was applied. The current pulse height and pulse on-time was identified for maximizing Net Transient Advantage, a newly defined metric. The corresponding pulse height and pulse on-time was utilized for the system model. Along with the traditional steady state starting current of Imax, Iopt was employed. The pulse shape was an isosceles triangle. For the system model, metrics new to pulse cooling were Qc, power consumption and COP. The effects of optimized current pulses were studied by changing system variables. Further studies explored time spacing between pulses and temperature distribution in the thermoelement. It was found net Q c over an entire pulse event can be improved over Imax steady operation but not over steady I opt operation. Qc can be improved over Iopt operation but only during the early part of the pulse event. COP is reduced in transient pulse operation due to the different time constants of Qc and Pin. In some cases lower performance interface materials allow more Qc and better COP during transient operation than higher performance interface materials

Fabrication of thin-film thermoelectric generators with ball lenses for conversion of near-infrared solar light

NASA Astrophysics Data System (ADS)

Ito, Yoshitaka; Mizoshiri, Mizue; Mikami, Masashi; Kondo, Tasuku; Sakurai, Junpei; Hata, Seiichi

2017-06-01

We designed and fabricated thin-film thermoelectric generators (TEGs) with ball lenses, which separated visible light and near-infrared (NIR) solar light using a chromatic aberration. The transmitted visible light was used as daylight and the NIR light was used for thermoelectric generation. Solar light was estimated to be separated into the visible light and NIR light by a ray tracing method. 92.7% of the visible light was used as daylight and 9.9% of the NIR light was used for thermoelectric generation. Then, the temperature difference of the pn junctions of the TEG surface was 0.71 K, determined by heat conduction analysis using a finite element method. The thin-film TEGs were fabricated using lithography and deposition processes. When the solar light (A.M. 1.5) was irradiated to the TEGs, the open-circuit voltage and maximum power were 4.5 V/m2 and 51 µW/m2, respectively. These TEGs are expected to be used as an energy supply for Internet of Things sensors.

Study of a thermoelectric system equipped with a maximum power point tracker for stand-alone electric generation.

NASA Astrophysics Data System (ADS)

Favarel, C.; Champier, D.; Bédécarrats, J. P.; Kousksou, T.; Strub, F.

2012-06-01

According to the International Energy Agency, 1.4 billion people are without electricity in the poorest countries and 2.5 billion people rely on biomass to meet their energy needs for cooking in developing countries. The use of cooking stoves equipped with small thermoelectric generator to provide electricity for basic needs (LED, cell phone and radio charging device) is probably a solution for houses far from the power grid. The cost of connecting every house with a landline is a lot higher than dropping thermoelectric generator in each house. Thermoelectric generators have very low efficiency but for isolated houses, they might become really competitive. Our laboratory works in collaboration with plane`te-bois (a non governmental organization) which has developed energy-efficient multifunction (cooking and hot water) stoves based on traditional stoves designs. A prototype of a thermoelectric generator (Bismuth Telluride) has been designed to convert a small part of the energy heating the sanitary water into electricity. This generator can produce up to 10 watts on an adapted load. Storing this energy in a battery is necessary as the cooking stove only works a few hours each day. As the working point of the stove varies a lot during the use it is also necessary to regulate the electrical power. An electric DC DC converter has been developed with a maximum power point tracker (MPPT) in order to have a good efficiency of the electronic part of the thermoelectric generator. The theoretical efficiency of the MMPT converter is discussed. First results obtained with a hot gas generator simulating the exhaust of the combustion chamber of a cooking stove are presented in the paper.

Highly Efficient Segmented p-type Thermoelectric Leg

NASA Astrophysics Data System (ADS)

Sadia, Yatir; Ben-Yehuda, Ohad; Gelbstein, Yaniv

In the past years, energy demands in the entire world have been constantly increasing. This fact, coupled with the requirement for decreasing the world's dependence on fossil fuels, has given rise to the need for alternative energy sources. While no single alternative energy source can solely replace the traditional fossil fuels, the combination of several alternative power sources can greatly decrease their usage. Thermoelectricity is one way to produce such energy via the harvesting of waste heat into electricity. One common example is the automobile industry which in the past few years had been looking into the option of harvesting the waste heat created by the engine, around the exhaust pipe and in the catalytic converter. Thermoelectricity is ideal for such application since it can convert the energy directly into electric current without any moving parts, thereby extending the life cycle of the operation.

Effects of Heat Generation on Nuclear Waste Disposal in Salt

NASA Astrophysics Data System (ADS)

Clayton, D. J.

2008-12-01

Disposal of nuclear waste in salt is an established technology, as evidenced by the successful operations of the Waste Isolation Pilot Plant (WIPP) since 1999. The WIPP is located in bedded salt in southeastern New Mexico and is a deep underground facility for transuranic (TRU) nuclear waste disposal. There are many advantages for placing radioactive wastes in a geologic bedded-salt environment. One desirable mechanical characteristic of salt is that it flows plastically with time ("creeps"). The rate of salt creep is a strong function of temperature and stress differences. Higher temperatures and deviatoric stresses increase the creep rate. As the salt creeps, induced fractures may be closed and eventually healed, which then effectively seals the waste in place. With a backfill of crushed salt emplaced around the waste, the salt creep can cause the crushed salt to reconsolidate and heal to a state similar to intact salt, serving as an efficient seal. Experiments in the WIPP were conducted to investigate the effects of heat generation on the important phenomena and processes in and around the repository (Munson et al. 1987; 1990; 1992a; 1992b). Brine migration towards the heaters was induced from the thermal gradient, while salt creep rates showed an exponential dependence on temperature. The project "Backfill and Material Behavior in Underground Salt Repositories, Phase II" (BAMBUS II) studied the crushed salt backfill and material behavior with heat generation at the Asse mine located near Remlingen, Germany (Bechthold et al. 2004). Increased salt creep rates and significant reconsolidation of the crushed salt were observed at the termination of the experiment. Using the data provided from both projects, exploratory modeling of the thermal-mechanical response of salt has been conducted with varying thermal loading and waste spacing. Increased thermal loading and decreased waste spacing drive the system to higher temperatures, while both factors are desired to

Thermoelectric Device Fabrication Using Thermal Spray and Laser Micromachining

NASA Astrophysics Data System (ADS)

Tewolde, Mahder; Fu, Gaosheng; Hwang, David J.; Zuo, Lei; Sampath, Sanjay; Longtin, Jon P.

2016-02-01

Thermoelectric generators (TEGs) are solid-state devices that convert heat directly into electricity. They are used in many engineering applications such as vehicle and industrial waste-heat recovery systems to provide electrical power, improve operating efficiency and reduce costs. State-of-art TEG manufacturing is based on prefabricated materials and a labor-intensive process involving soldering, epoxy bonding, and mechanical clamping for assembly. This reduces their durability and raises costs. Additive manufacturing technologies, such as thermal spray, present opportunities to overcome these challenges. In this work, TEGs have been fabricated for the first time using thermal spray technology and laser micromachining. The TEGs are fabricated directly onto engineering component surfaces. First, current fabrication techniques of TEGs are presented. Next, the steps required to fabricate a thermal spray-based TEG module, including the formation of the metallic interconnect layers and the thermoelectric legs are presented. A technique for bridging the air gap between two adjacent thermoelectric elements for the top layer using a sacrificial filler material is also demonstrated. A flat 50.8 mm × 50.8 mm TEG module is fabricated using this method and its performance is experimentally characterized and found to be in agreement with expected values of open-circuit voltage based on the materials used.

Measurement and simulation of thermoelectric efficiency for single leg

NASA Astrophysics Data System (ADS)

Hu, Xiaokai; Yamamoto, Atsushi; Ohta, Michihiro; Nishiate, Hirotaka

2015-04-01

Thermoelectric efficiency measurements were carried out on n-type bismuth telluride legs with the hot-side temperature at 100 and 150 °C. The electric power and heat flow were measured individually. Water coolant was utilized to maintain the cold-side temperature and to measure heat flow out of the cold side. Leg length and vacuum pressure were studied in terms of temperature difference across the leg, open-circuit voltage, internal resistance, and heat flow. Finite-element simulation on thermoelectric generation was performed in COMSOL Multiphysics, by inputting two-side temperatures and thermoelectric material properties. The open-circuit voltage and resistance were in good agreement between the measurement and simulation. Much larger heat flows were found in measurements, since they were comprised of conductive, convective, and radiative contributions. Parasitic heat flow was measured in the absence of bismuth telluride leg, and the conductive heat flow was then available. Finally, the maximum thermoelectric efficiency was derived in accordance with the electric power and the conductive heat flow.

Analysis of Advanced Thermoelectric Materials and Their Functional Limits

NASA Technical Reports Server (NTRS)

Kim, Hyun Jung

2015-01-01

The world's demand for energy is increasing dramatically, but the best energy conversion systems operate at approximately 30% efficiency. One way to decrease energy loss is in the recovery of waste heat using thermoelectric (TE) generators. A TE generator is device that generates electricity by exploiting heat flow across a thermal gradient. The efficiency of a TE material for power generation and cooling is determined by the dimensionless Figure of Merit (ZT): ZT = S(exp. 2)sigmaT/?: where S is the Seebeck coefficient, sigma is the electrical conductivity, T is the absolute temperature, and ? is the thermal conductivity. The parameters are not physically independent, but intrinsically coupled since they are a function of the transport properties of electrons. Traditional research on TE materials has focused on synthesizing bulk semiconductor-type materials that have low thermal conductivity and high electrical conductivity affording ZT values of 1. The optimization of the s/? ratio is difficult to achieve using current material formats, as these material constants are complementary. Recent areas of research are focusing on using nanostructural artifacts that introduce specific dislocations and boundary conditions that scatter the phonons. This disrupts the physical link between thermal (phonon) and electrical (electron) transport. The result is that ? is decreased without decreasing s. These material formats give ZT values of up to 2 which represent approximately 18% energy gain from waste heat recovery. The next challenge in developing the next generation of TE materials with superior performance is to tailor the interconnected thermoelectric physical parameters of the material system. In order to approach this problem, the fundamental physics of each parameter S, sigma, and ? need to be physically understood in their context of electron/phonon interaction for the construction of new high ZT thermoelectric devices. Is it possible to overcome the physical limit

Realizing high figure of merit in heavy-band p-type half-Heusler thermoelectric materials

PubMed Central

Fu, Chenguang; Bai, Shengqiang; Liu, Yintu; Tang, Yunshan; Chen, Lidong; Zhao, Xinbing; Zhu, Tiejun

2015-01-01

Solid-state thermoelectric technology offers a promising solution for converting waste heat to useful electrical power. Both high operating temperature and high figure of merit zT are desirable for high-efficiency thermoelectric power generation. Here we report a high zT of ∼1.5 at 1,200 K for the p-type FeNbSb heavy-band half-Heusler alloys. High content of heavier Hf dopant simultaneously optimizes the electrical power factor and suppresses thermal conductivity. Both the enhanced point-defect and electron–phonon scatterings contribute to a significant reduction in the lattice thermal conductivity. An eight couple prototype thermoelectric module exhibits a high conversion efficiency of 6.2% and a high power density of 2.2 W cm−2 at a temperature difference of 655 K. These findings highlight the optimization strategy for heavy-band thermoelectric materials and demonstrate a realistic prospect of high-temperature thermoelectric modules based on half-Heusler alloys with low cost, excellent mechanical robustness and stability. PMID:26330371

Temporal Evolution of Water Use for Thermoelectric Generation

NASA Astrophysics Data System (ADS)

Reedy, R. C.; Scanlon, B. R.

2013-12-01

The long lifespan of power plants (30 - 50 yr) results in the current power plant fleet representing a legacy of past variations in fuel availability and costs, water availability and water rights, and advances in technologies, such as combined cycle plants, which impact trends in water consumption. The objective of this study was to reconstruct past water consumption and withdrawal of thermoelectric generation based on data on controls, including fuel types, generator technologies, and cooling systems, using Texas as a case study and comparing with the US. Fuel sources in Texas varied over time, from predominantly natural gas in the 1960s and early 1970s to coal and nuclear sources following the 1973 oil embargo and more recently to large increases in natural gas generation (85% increase 1998 - 2004) in response to hydraulic fracturing and low natural gas prices. The dominant generator technology in Texas was steam turbines until the early 1990s; however, combined cycle plants markedly increased in the late 1990s (400% increase 1998 - 2004). Proliferation of cooling ponds in Texas, mostly in the 1970s and 1980s (340% increase) reflects availability of large quantities of unappropriated surface water and increases in water rights permitting during this time and lower cost and higher cooling efficiency of ponds relative to wet cooling towers. Water consumption for thermoelectricity in Texas in 2010 totaled ~0.53 km3 (0.43 million acre feet, maf), accounting for ~4% of total state water consumption. High water withdrawals (32.3 km3, 26.2 maf) mostly reflect circulation between cooling ponds and power plants. About a third of the water withdrawals is not required for cooling and reflects circulation by idling plants being used as peaking plants. Controls on water consumption include (1) generator technology/thermal efficiency and (2) cooling system resulting in statewide consumption for natural gas combined cycle generators with mostly cooling towers being 60% lower

Fully Electrical Modeling of Thermoelectric Generators with Contact Thermal Resistance Under Different Operating Conditions

NASA Astrophysics Data System (ADS)

Siouane, Saima; Jovanović, Slaviša; Poure, Philippe

2017-01-01

The Seebeck effect is used in thermoelectric generators (TEGs) to supply electronic circuits by converting the waste thermal into electrical energy. This generated electrical power is directly proportional to the temperature difference between the TEG module's hot and cold sides. Depending on the applications, TEGs can be used either under constant temperature gradient between heat reservoirs or constant heat flow conditions. Moreover, the generated electrical power of a TEG depends not only on these operating conditions, but also on the contact thermal resistance. The influence of the contact thermal resistance on the generated electrical power have already been extensively reported in the literature. However, as reported in Park et al. (Energy Convers Manag 86:233, 2014) and Montecucco and Knox (IEEE Trans Power Electron 30:828, 2015), while designing TEG-powered circuit and systems, a TEG module is mostly modeled with a Thévenin equivalent circuit whose resistance is constant and voltage proportional to the temperature gradient applied to the TEG's terminals. This widely used simplified electrical TEG model is inaccurate and not suitable under constant heat flow conditions or when the contact thermal resistance is considered. Moreover, it does not provide realistic behaviour corresponding to the physical phenomena taking place in a TEG. Therefore, from the circuit designer's point of view, faithful and fully electrical TEG models under different operating conditions are needed. Such models are mainly necessary to design and evaluate the power conditioning electronic stages and the maximum power point tracking algorithms of a TEG power supply. In this study, these fully electrical models with the contact thermal resistance taken into account are presented and the analytical expressions of the Thévenin equivalent circuit parameters are provided.

Mapping the impacts of thermoelectric power generation: a global, spatially explicit database

NASA Astrophysics Data System (ADS)

Raptis, Catherine; Pfister, Stephan

2017-04-01

Thermoelectric power generation is associated with environmental pressures resulting from emissions to air and water, as well as water consumption. The need to achieve global coverage in related studies has become pressing in view of climate change. At the same time, the ability to quantify impacts from power production on a high resolution remains pertinent, given their highly regionalized nature, particularly when it comes to water-related impacts. Efforts towards global coverage have increased in recent years, but most work on the impacts of global electricity production presents a coarse geographical differentiation. Over the past few years we have begun a concerted effort to create and make available a global georeferenced inventory of thermoelectric power plant operational characteristics and emissions, by modelling the relevant processes on the highest possible level: that of a generating unit. Our work extends and enhances a commercially available global power plant database, and so far includes: - Georeferencing the generating units and populating the gaps in their steam properties. - Identifying the cooling system for 92% of the global installed thermoelectric power capacity. - Using the completed steam property data, along with local environmental temperature data, to systematically solve the Rankine cycle for each generating unit, involving: i) distinguishing between simple, reheat, and cogenerative cycles, and accounting for particularities in nuclear power cycles; ii) accounting for the effect of different cooling systems (once-through, recirculating (wet tower), dry cooling) on the thermodynamic cycle. One of the direct outcomes of solving the Rankine cycle is the cycle efficiency, an indispensable parameter in any study related to power production, including the quantification of air emissions and water consumption. Another direct output, for those units employing once-through cooling, is the rate of heat rejection to water, which can lead to

Thermionic Energy Conversion (TEC) topping thermoelectrics

NASA Technical Reports Server (NTRS)

Morris, J. F.

1981-01-01

Performance expectations for thermionic and thermoelectric energy conversion systems are reviewed. It is noted that internal radiation effects diminish thermoelectric figures of merit significantly at 1000 K and substantially at 2000 K; the effective thermal conductivity contribution of intrathermoelectric radiative dissipation increases with the third power of temperature. It is argued that a consideration of thermoelectric power generation with high temperature heat sources should include utilization of thermionic energy conversion (TEC) topping thermoelectrics. However TEC alone or TEC topping more efficient conversion systems like steam or gas turbines, combined cycles, or Stirling engines would be more desirable generally.

High Temperature Integrated Thermoelectric Ststem and Materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mike S. H. Chu

2011-06-06

The final goal of this project is to produce, by the end of Phase II, an all ceramic high temperature thermoelectric module. Such a module design integrates oxide ceramic n-type, oxide ceramic p-type materials as thermoelectric legs and oxide ceramic conductive material as metalizing connection between n-type and p-type legs. The benefits of this all ceramic module are that it can function at higher temperatures (> 700 C), it is mechanically and functionally more reliable and it can be scaled up to production at lower cost. With this all ceramic module, millions of dollars in savings or in new opportunitiesmore » recovering waste heat from high temperature processes could be made available. A very attractive application will be to convert exhaust heat from a vehicle to reusable electric energy by a thermoelectric generator (TEG). Phase I activities were focused on evaluating potential n-type and p-type oxide compositions as the thermoelectric legs. More than 40 oxide ceramic powder compositions were made and studied in the laboratory. The compositions were divided into 6 groups representing different material systems. Basic ceramic properties and thermoelectric properties of discs sintered from these powders were measured. Powders with different particles sizes were made to evaluate the effects of particle size reduction on thermoelectric properties. Several powders were submitted to a leading thermoelectric company for complete thermoelectric evaluation. Initial evaluation showed that when samples were sintered by conventional method, they had reasonable values of Seebeck coefficient but very low values of electrical conductivity. Therefore, their power factors (PF) and figure of merits (ZT) were too low to be useful for high temperature thermoelectric applications. An unconventional sintering method, Spark Plasma Sintering (SPS) was determined to produce better thermoelectric properties. Particle size reduction of powders also was found to have some positive

Determination of Thermoelectric Module Efficiency A Survey

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Hsin; McCarty, Robin; Salvador, James R.

2014-01-01

The development of thermoelectrics (TE) for energy conversion is in the transition phase from laboratory research to device development. There is an increasing demand to accurately determine the module efficiency, especially for the power generation mode. For many thermoelectrics, the figure of merit, ZT, of the material sometimes cannot be fully realized at the device level. Reliable efficiency testing of thermoelectric modules is important to assess the device ZT and provide the end-users with realistic values on how much power can be generated under specific conditions. We conducted a general survey of efficiency testing devices and their performance. The resultsmore » indicated the lack of industry standards and test procedures. This study included a commercial test system and several laboratory systems. Most systems are based on the heat flow meter method and some are based on the Harman method. They are usually reproducible in evaluating thermoelectric modules. However, cross-checking among different systems often showed large errors that are likely caused by unaccounted heat loss and thermal resistance. Efficiency testing is an important area for the thermoelectric community to focus on. A follow-up international standardization effort is planned.« less

Titanium nitride electrodes for thermoelectric generators

DOEpatents

Novak, Robert F.; Schmatz, Duane J.; Hunt, Thomas K.

1987-12-22

The invention is directed to a composite article suitable for use in thermoelectric generators. The article comprises a thin film of titanium nitride as an electrode deposited onto solid electrolyte. The invention is also directed to the method of making same.

Maximum Potential of the Car Cabin Temperature in the Outdoor Parking Conditions as a Source of Energy in Thermoelectric Generator

NASA Astrophysics Data System (ADS)

Sunawar, A.; Garniwa, I.

2017-03-01

Cars using the principle of converting heat energy into mechanical energy, but a lot of wasted heat energy not entirely transformed into mechanical energy, studies have been conducted that converts the heat energy into electrical energy using the principle thermoelectrically. However, there are many other energies that can be harnessed from the car, such as when the car is parked in the sun or driving in the heat of the sun, the temperature in the cabin can reach 80 degrees Celsius. The heat can be harmful to humans and the children immediately into the vehicle, as well as for the goods stored in the cabin if it contains toxins can evaporate because of the heat and dangerous. The danger can be prevented by reducing the heat in the cabin and transform into other forms of energy such as electricity. By providing a temperature difference of 40 degrees on the cold side of the module can be acquired electricity thermoelectrically up to 0.17W for one of its module, if it is made a module block the energy produced is enough to lower the temperature and charge batteries for further cooling. This study will use experiment method to get the maximum drop in temperature in the car cabin

Modeling transient heat transfer in nuclear waste repositories.

PubMed

Yang, Shaw-Yang; Yeh, Hund-Der

2009-09-30

The heat of high-level nuclear waste may be generated and released from a canister at final disposal sites. The waste heat may affect the engineering properties of waste canisters, buffers, and backfill material in the emplacement tunnel and the host rock. This study addresses the problem of the heat generated from the waste canister and analyzes the heat distribution between the buffer and the host rock, which is considered as a radial two-layer heat flux problem. A conceptual model is first constructed for the heat conduction in a nuclear waste repository and then mathematical equations are formulated for modeling heat flow distribution at repository sites. The Laplace transforms are employed to develop a solution for the temperature distributions in the buffer and the host rock in the Laplace domain, which is numerically inverted to the time-domain solution using the modified Crump method. The transient temperature distributions for both the single- and multi-borehole cases are simulated in the hypothetical geological repositories of nuclear waste. The results show that the temperature distributions in the thermal field are significantly affected by the decay heat of the waste canister, the thermal properties of the buffer and the host rock, the disposal spacing, and the thickness of the host rock at a nuclear waste repository.

Optimization of thermoelectric cooling regimes for heat-loaded elements taking into account the thermal resistance of the heat-spreading system

NASA Astrophysics Data System (ADS)

Vasil'ev, E. N.

2017-09-01

A mathematical model has been proposed for analyzing and optimizing thermoelectric cooling regimes for heat-loaded elements of engineering and electronic devices. The model based on analytic relations employs the working characteristics of thermoelectric modules as the initial data and makes it possible to determine the temperature regime and the optimal values of the feed current for the modules taking into account the thermal resistance of the heat-spreading system.

In-line thermoelectric module

DOEpatents

Pento, Robert; Marks, James E.; Staffanson, Clifford D.

2000-01-01

A thermoelectric module with a plurality of electricity generating units each having a first end and a second end, the units being arranged first end to second end along an in-line axis. Each unit includes first and second elements each made of a thermoelectric material, an electrically conductive hot member arranged to heat one side of the first element, and an electrically conductive cold member arranged to cool another side of the first element and to cool one side of the second element. The hot member, the first element, the cold member and the second element are supported in a fixture, are electrically connected respectively to provide an electricity generating unit, and are arranged respectively in positions along the in-line axis. The individual components of each generating unit and the respective generating units are clamped in their in-line positions by a loading bolt at one end of the fixture and a stop wall at the other end of the fixture. The hot members may have a T-shape and the cold members an hourglass shape to facilitate heat transfer. The direction of heat transfer through the hot members may be perpendicular to the direction of heat transfer through the cold members, and both of these heat transfer directions may be perpendicular to the direction of current flow through the module.

Design, crystal growth, and physical properties of low-temperature thermoelectric materials

NASA Astrophysics Data System (ADS)

Fuccillo, Michael K.

Thermoelectric materials serve as the foundation for two important modern technologies, namely 1) solid-state cooling, which enables small-area refrigeration without vibrations or moving parts, and 2) thermoelectric power generation, which has important implications for waste heat recovery and improved sources of alternative energy. Although the overall field of thermoelectrics research has been active for decades, and several consumer and industrial products have already been commercialized, the design and synthesis of new thermoelectrics that outperform long-standing state of the art materials has proven extremely challenging. This is particularly true for low-temperature refrigeration applications, which is the focus of this work; however, scientific advances in this area generally support power generation as well. In order to achieve more efficient materials for virtually all thermoelectric applications, improved materials design principles must be developed and synthetic procedures must be better understood. We aim to contribute to these goals by studying two classes of materials, namely 1) the tetradymites Bi2TeSe 2 and Bi2Te2Se, which are close relatives of state of the art thermoelectric cooling materials, and 2) Kondo insulating (-like) FeSb2 and FeSi, which possess anomalously enhanced low-temperature thermoelectric properties that arise from exotic electronic and magnetic properties. The organization of this dissertation is as follows: Chapter 1 is a brief perspective on solid-state chemistry. Chapter 2 presents experimental methods for synthesizing and characterizing thermoelectric materials. In Chapter 3, two original research projects are discussed: first, work on the tetradymite Bi2TeSe2 doped with Sb to achieve an n- to p-type transition, and second, the tetradymite Bi2Te2Se with chemical defects through two different methods. Chapter 4 gives the magnetic and transport properties of FeSb 2--RuSb2 alloys, a family of compounds exemplifying what we

Recent progress in oxide thermoelectric materials: p-type Ca3Co4O9 and n-type SrTiO3(-).

PubMed

Ohta, Hiromichi; Sugiura, Kenji; Koumoto, Kunihito

2008-10-06

Thermoelectric energy conversion technology to convert waste heat into electricity has received much attention. In addition, metal oxides have recently been considered as thermoelectric power generation materials that can operate at high temperatures on the basis of their potential advantages over heavy metallic alloys in chemical and thermal robustness. We have fabricated high-quality epitaxial films composed of oxide thermoelectric materials that are suitable for clarifying the intrinsic "real" properties. This review focuses on the thermoelectric properties of two representative oxide epitaxial films, p-type Ca 3Co 4O 9 and n-type SrTiO 3, which exhibit the best thermoelectric figures of merit, ZT (= S (2)sigma Tkappa (-1), S = Seebeck coefficient, sigma = electrical conductivity, kappa = thermal conductivity, and T = absolute temperature) among oxide thermoelectric materials reported to date. In addition, we introduce the recently discovered giant S of two-dimensional electrons confined within a unit cell layer thickness ( approximately 0.4 nm) of SrTiO 3.

Method of controlling temperature of a thermoelectric generator in an exhaust system

DOEpatents

Prior, Gregory P; Reynolds, Michael G; Cowgill, Joshua D

2013-05-21

A method of controlling the temperature of a thermoelectric generator (TEG) in an exhaust system of an engine is provided. The method includes determining the temperature of the heated side of the TEG, determining exhaust gas flow rate through the TEG, and determining the exhaust gas temperature through the TEG. A rate of change in temperature of the heated side of the TEG is predicted based on the determined temperature, the determined exhaust gas flow rate, and the determined exhaust gas temperature through the TEG. Using the predicted rate of change of temperature of the heated side, exhaust gas flow rate through the TEG is calculated that will result in a maximum temperature of the heated side of the TEG less than a predetermined critical temperature given the predicted rate of change in temperature of the heated side of the TEG. A corresponding apparatus is provided.

Molybdenum oxide electrodes for thermoelectric generators

DOEpatents

Schmatz, Duane J.

1989-01-01

The invention is directed to a composite article suitable for use in thermoelectric generators. The article comprises a thin film comprising molybdenum oxide as an electrode deposited by physical deposition techniques onto solid electrolyte. The invention is also directed to the method of making same.

Development of a preprototype thermoelectric integrated membrane evaporation subsystem for water recovery

NASA Technical Reports Server (NTRS)

Winkler, H. E.; Roebelen, G. J., Jr.

1980-01-01

A three-man urine water recovery preprototype subsystem using a new concept to provide efficient potable water recovery from waste fluids on extended duration space flights has been designed, fabricated, and tested. Low power, compactness, and gravity insensitive operation are featured in this vacuum distillation subsystem that combines a hollow fiber polysulfone membrane evaporator with a thermoelectric heat pump. Application and integration of these key elements have solved problems inherent in previous reclamation subsystem designs. The hollow fiber elements provide positive liquid/gas phase control with no moving parts other than a waste liquid recirculation pump and a product water withdrawal pump. Tubular membranes provide structural integrity, improving on previous flat sheet membrane designs. A thermoelectric heat pump provides latent energy recovery.

Using Thermoelectric Coolers to Enhance Loop Heat Pipe Performance

NASA Technical Reports Server (NTRS)

Ku, Jentung; Butler, Dan; Ottenstein, Laura; Birur, Gajanana

2005-01-01

Contents include the following: Loop Heat Pipe (LHP) operating temperature. LHP start-up issues. How Thermoelectric Cooler (TECs) can enhance LHP performance: start-up; operating temperature control. Experimental studies: LHP with one evaporator and one condenser; LHP with two evaporators and two condensers. Conclusion.

Numerical modeling of the thermoelectric cooler with a complementary equation for heat circulation in air gaps

NASA Astrophysics Data System (ADS)

Fang, En; Wu, Xiaojie; Yu, Yuesen; Xiu, Junrui

2017-03-01

In this paper, a numerical model is developed by combining thermodynamics with heat transfer theory. Taking inner and external multi-irreversibility into account, it is with a complementary equation for heat circulation in air gaps of a steady cooling system with commercial thermoelectric modules operating in refrigeration mode. With two modes concerned, the equation presents the heat flowing through air gaps which forms heat circulations between both sides of thermoelectric coolers (TECs). In numerical modelling, a TEC is separated as two temperature controlled constant heat flux reservoirs in a thermal resistance network. In order to obtain the parameter values, an experimental apparatus with a commercial thermoelectric cooler was built to characterize the performance of a TEC with heat source and sink assembly. At constant power dissipation, steady temperatures of heat source and both sides of the thermoelectric cooler were compared with those in a standard numerical model. The method displayed that the relationship between Φf and the ratio Φ_{c}'/Φ_{c} was linear as expected. Then, for verifying the accuracy of proposed numerical model, the data in another system were recorded. It is evident that the experimental results are in good agreement with simulation(proposed model) data at different heat transfer rates. The error is small and mainly results from the instabilities of thermal resistances with temperature change and heat flux, heat loss of the device vertical surfaces and measurements.

Validation, Optimization and Simulation of a Solar Thermoelectric Generator Model

NASA Astrophysics Data System (ADS)

Madkhali, Hadi Ali; Hamil, Ali; Lee, HoSung

2017-12-01

This study explores thermoelectrics as a viable option for small-scale solar thermal applications. Thermoelectric technology is based on the Seebeck effect, which states that a voltage is induced when a temperature gradient is applied to the junctions of two differing materials. This research proposes to analyze, validate, simulate, and optimize a prototype solar thermoelectric generator (STEG) model in order to increase efficiency. The intent is to further develop STEGs as a viable and productive energy source that limits pollution and reduces the cost of energy production. An empirical study (Kraemer et al. in Nat Mater 10:532, 2011) on the solar thermoelectric generator reported a high efficiency performance of 4.6%. The system had a vacuum glass enclosure, a flat panel (absorber), thermoelectric generator and water circulation for the cold side. The theoretical and numerical approach of this current study validated the experimental results from Kraemer's study to a high degree. The numerical simulation process utilizes a two-stage approach in ANSYS software for Fluent and Thermal-Electric Systems. The solar load model technique uses solar radiation under AM 1.5G conditions in Fluent. This analytical model applies Dr. Ho Sung Lee's theory of optimal design to improve the performance of the STEG system by using dimensionless parameters. Applying this theory, using two cover glasses and radiation shields, the STEG model can achieve a highest efficiency of 7%.

Highly Efficient Multilayer Thermoelectric Devices

NASA Technical Reports Server (NTRS)

Boufelfel, Ali

2006-01-01

Multilayer thermoelectric devices now at the prototype stage of development exhibit a combination of desirable characteristics, including high figures of merit and high performance/cost ratios. These devices are capable of producing temperature differences of the order of 50 K in operation at or near room temperature. A solvent-free batch process for mass production of these state-of-the-art thermoelectric devices has also been developed. Like prior thermoelectric devices, the present ones have commercial potential mainly by virtue of their utility as means of controlled cooling (and/or, in some cases, heating) of sensors, integrated circuits, and temperature-critical components of scientific instruments. The advantages of thermoelectric devices for such uses include no need for circulating working fluids through or within the devices, generation of little if any noise, and high reliability. The disadvantages of prior thermoelectric devices include high power consumption and relatively low coefficients of performance. The present development program was undertaken in the hope of reducing the magnitudes of the aforementioned disadvantages and, especially, obtaining higher figures of merit for operation at and near room temperature. Accomplishments of the program thus far include development of an algorithm to estimate the heat extracted by, and the maximum temperature drop produced by, a thermoelectric device; solution of the problem of exchange of heat between a thermoelectric cooler and a water-cooled copper block; retrofitting of a vacuum chamber for depositing materials by sputtering; design of masks; and fabrication of multilayer thermoelectric devices of two different designs, denoted I and II. For both the I and II designs, the thicknesses of layers are of the order of nanometers. In devices of design I, nonconsecutive semiconductor layers are electrically connected in series. Devices of design II contain superlattices comprising alternating electron

Designing high-performance layered thermoelectric materials through orbital engineering

PubMed Central

Zhang, Jiawei; Song, Lirong; Madsen, Georg K. H.; Fischer, Karl F. F.; Zhang, Wenqing; Shi, Xun; Iversen, Bo B.

2016-01-01

Thermoelectric technology, which possesses potential application in recycling industrial waste heat as energy, calls for novel high-performance materials. The systematic exploration of novel thermoelectric materials with excellent electronic transport properties is severely hindered by limited insight into the underlying bonding orbitals of atomic structures. Here we propose a simple yet successful strategy to discover and design high-performance layered thermoelectric materials through minimizing the crystal field splitting energy of orbitals to realize high orbital degeneracy. The approach naturally leads to design maps for optimizing the thermoelectric power factor through forming solid solutions and biaxial strain. Using this approach, we predict a series of potential thermoelectric candidates from layered CaAl2Si2-type Zintl compounds. Several of them contain nontoxic, low-cost and earth-abundant elements. Moreover, the approach can be extended to several other non-cubic materials, thereby substantially accelerating the screening and design of new thermoelectric materials. PMID:26948043

A study of hear sink performance in air and soil for use in a thermoelectric energy harvesting device

NASA Technical Reports Server (NTRS)

Snyder, J.; Lawrence, E. E.

2002-01-01

A suggested application of a thermoelectric generator is to exploit the natural temperature difference between the air and the soil to generate small amounts of electrical energy. Since the conversion efficiency of even the best thermoelectric generators available is very low, the performance of the heat sinks providing the heat flow is critical. By providing a constant heat input to various heat sinks, field tests of their thermal conductances in soil and in air were performed. Aprototype device without a thermoelectric generator was constructed, buried, and monitored to experimentally measure the heat flow achievable in such a system. Theoretical considerations for design and selection of improved heat sinks are also presented. In particular, the method of shape factoranalysis is used to give rough estimates and upper bounds for the thermal conductance of a passive heat sink buried in soil.

All dispenser printed flexible 3D structured thermoelectric generators

NASA Astrophysics Data System (ADS)

Cao, Z.; Shi, J. J.; Torah, R. N.; Tudor, M. J.; Beeby, S. P.

2015-12-01

This work presents a vertically fabricated 3D thermoelectric generator (TEG) by dispenser printing on flexible polyimide substrate. This direct-write technology only involves printing of electrodes, thermoelectric active materials and structure material, which needs no masks to transfer the patterns onto the substrate. The dimension for single thermoelectric element is 2 mm × 2 mm × 0.5 mm while the distance between adjacent cubes is 1.2 mm. The polymer structure layer was used to support the electrodes which are printed to connect the top ends of the thermoelectric material and ensure the flexibility as well. The advantages and the limitations of the dispenser printed 3D TEGs will also be evaluated in this paper. The proposed method is potential to be a low-cost and scalable fabrication solution for TEGs.

Estimation of Thermoelectric Generator Performance by Finite Element Modeling

NASA Astrophysics Data System (ADS)

Ziolkowski, P.; Poinas, P.; Leszczynski, J.; Karpinski, G.; Müller, E.

2010-09-01

Prediction of thermoelectric performance parameters by numerical methods is an inherent part of thermoelectric generator (TEG) development and allows for time- and cost-saving assessment of material combinations and variations of crucial design parameters (e.g., shape, pellet length, and thermal coupling). Considering the complexity of a TEG system and its numerous affecting factors, the clarity and the flexibility of a mathematical treatment comes to the fore. Comfortable tools are provided by commercial finite element modeling (FEM) software offering powerful geometry interfaces, mesh generators, solvers, and postprocessing options. We describe the level of development and the simulation results of a three dimensional (3D) TEG FEM. Using ANSYS 11.0, we implemented and simulated a TEG module geometry under various conditions. Comparative analytical one dimensional (1D) results and a direct comparison with inhouse-developed TEG simulation software show the consistency of results. Several pellet aspect ratios and contact property configurations (thermal/electrical interface resistance) were evaluated for their impact on the TEG performance as well as parasitic effects such as convection, radiation, and conductive heat bypass. The scenarios considered revealed the highest efficiency decay for convectionally loaded setups (up to 4.8%pts), followed by the impacts of contact resistances (up to 4.8%pts), by radiation (up to 0.56%pts), and by thermal conduction of a solid filling material within the voids of the module construction (up to 0.14%pts).

Alternatives Generation and Analysis for Heat Removal from High Level Waste Tanks

DOE Office of Scientific and Technical Information (OSTI.GOV)

WILLIS, W.L.

This document addresses the preferred combination of design and operational configurations to provide heat removal from high-level waste tanks during Phase 1 waste feed delivery to prevent the waste temperature from exceeding tank safety requirement limits. An interim decision for the preferred method to remove the heat from the high-level waste tanks during waste feed delivery operations is presented herein.

Atomically thick bismuth selenide freestanding single layers achieving enhanced thermoelectric energy harvesting.

PubMed

Sun, Yongfu; Cheng, Hao; Gao, Shan; Liu, Qinghua; Sun, Zhihu; Xiao, Chong; Wu, Changzheng; Wei, Shiqiang; Xie, Yi

2012-12-19

Thermoelectric materials can realize significant energy savings by generating electricity from untapped waste heat. However, the coupling of the thermoelectric parameters unfortunately limits their efficiency and practical applications. Here, a single-layer-based (SLB) composite fabricated from atomically thick single layers was proposed to optimize the thermoelectric parameters fully. Freestanding five-atom-thick Bi(2)Se(3) single layers were first synthesized via a scalable interaction/exfoliation strategy. As revealed by X-ray absorption fine structure spectroscopy and first-principles calculations, surface distortion gives them excellent structural stability and a much increased density of states, resulting in a 2-fold higher electrical conductivity relative to the bulk material. Also, the surface disorder and numerous interfaces in the Bi(2)Se(3) SLB composite allow for effective phonon scattering and decreased thermal conductivity, while the 2D electron gas and energy filtering effect increase the Seebeck coefficient, resulting in an 8-fold higher figure of merit (ZT) relative to the bulk material. This work develops a facile strategy for synthesizing atomically thick single layers and demonstrates their superior ability to optimize the thermoelectric energy harvesting.

Analysis of Thermal Power Generation Capacity for a Skutterudite-Based Thermoelectric Functional Structure

NASA Astrophysics Data System (ADS)

Sun, Yajing; Chen, Gang; Bai, Guanghui; Yang, Xuqiu; Li, Peng; Zhai, Pengcheng

2017-05-01

Due to military or other requirements for hypersonic aircraft, the energy supply devices with the advantages of small size and light weight are urgently needed. Compared with the traditional energy supply method, the skutterudite-based thermoelectric (TE) functional structure is expected to generate electrical energy with a smaller structural space in the hypersonic aircraft. This paper mainly focuses on the responded thermal and electrical characteristics of the skutterudite-based TE functional structure (TEFS) under strong heat flux loads. We conduct TE simulations on the transient model of the TEFS with consideration of the heat flux loads and thermal radiation in the hot end and the cooling effect of the phase change material (PCM) in the cold end. We investigate several influential factors on the power generation capacity, such as the phase transition temperature of the PCM, the heat flux loads, the thickness of the TE materials and the thermal conductivity of the frame materials. The results show that better power generation capacity can be achieved with thicker TE materials, lower phase transition temperature and suitable thermal conductivity of the frame materials.

Rigorous theory of graded thermoelectric converters including finite heat transfer coefficients

NASA Astrophysics Data System (ADS)

Gerstenmaier, York Christian; Wachutka, Gerhard

2017-11-01

Maximization of thermoelectric (TE) converter performance with an inhomogeneous material and electric current distribution has been investigated in previous literature neglecting thermal contact resistances to the heat reservoirs. The heat transfer coefficients (HTCs), defined as inverse thermal contact resistances per unit area, are thus infinite, whereas in reality, always parasitic thermal resistances, i.e., finite HTCs, are present. Maximization of the generated electric power and of cooling power in the refrigerator mode with respect to Seebeck coefficients and heat conductivity for a given profile of the material's TE figure of merit Z are mathematically ill-posed problems in the presence of infinite HTCs. As will be shown in this work, a fully self consistent solution is possible for finite HTCs, and in many respects, the results are fundamentally different. A previous theory for 3D devices will be extended to include finite HTCs and is applied to 1D devices. For the heat conductivity profile, an infinite number of solutions exist leading to the same device performance. Cooling power maximization for finite HTCs in 1D will lead to a strongly enhanced corresponding efficiency (coefficient of performance), whereas results with infinite HTCs lead to a non-monotonous temperature profile and coefficient of performance tending to zero for the prescribed heat conductivities. For maximized generated electric power, the corresponding generator efficiency is nearly a constant independent from the finite HTC values. The maximized efficiencies in the generator and cooling mode are equal to the efficiencies for the infinite HTC, provided that the corresponding powers approach zero. These and more findings are condensed in 4 theorems in the conclusions.

Hybrid photovoltaic and thermoelectric module for high concentration solar system

NASA Astrophysics Data System (ADS)

Tamaki, Ryo; Toyoda, Takeshi; Tamura, Yoichi; Matoba, Akinari; Minamikawa, Toshiharu; Tokuda, Masayuki; Masui, Megumi; Okada, Yoshitaka

2017-09-01

A photovoltaic (PV) and thermoelectric (TE) hybrid module was developed for application to high concentration solar systems. The waste heat from the solar cells under concentrated light illumination was utilized to generate additional electricity by assembling TE devices below the multi-junction solar cells (MJSCs). Considering the high operating temperature of the PV and TE hybrid module compared with conventional concentrator PV modules, the TE device could compensate a part of the MJSC efficiency degradation at high temperature. The performance investigation clarified the feasibility of the hybrid PV and TE module under highly concentrated sunlight illumination.

Thermoelectric Polymers and their Elastic Aerogels.

PubMed

Khan, Zia Ullah; Edberg, Jesper; Hamedi, Mahiar Max; Gabrielsson, Roger; Granberg, Hjalmar; Wågberg, Lars; Engquist, Isak; Berggren, Magnus; Crispin, Xavier

2016-06-01

Electronically conducting polymers constitute an emerging class of materials for novel electronics, such as printed electronics and flexible electronics. Their properties have been further diversified to introduce elasticity, which has opened new possibility for "stretchable" electronics. Recent discoveries demonstrate that conducting polymers have thermoelectric properties with a low thermal conductivity, as well as tunable Seebeck coefficients - which is achieved by modulating their electrical conductivity via simple redox reactions. Using these thermoelectric properties, all-organic flexible thermoelectric devices, such as temperature sensors, heat flux sensors, and thermoelectric generators, are being developed. In this article we discuss the combination of the two emerging fields: stretchable electronics and polymer thermoelectrics. The combination of elastic and thermoelectric properties seems to be unique for conducting polymers, and difficult to achieve with inorganic thermoelectric materials. We introduce the basic concepts, and state of the art knowledge, about the thermoelectric properties of conducting polymers, and illustrate the use of elastic thermoelectric conducting polymer aerogels that could be employed as temperature and pressure sensors in an electronic-skin. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Lyophilization for Water Recovery From Solid Waste

NASA Technical Reports Server (NTRS)

Flynn, Michael; Litwiller, Eric; Reinhard, Martin

2003-01-01

This abstract describes the development of a solid waste treatment system designed for a near term human exploration mission. The technology being developed is an energy- efficient lyophilization technique that recovers water from spacecraft solid waste. In the lyophilization process water in an aqueous waste is frozen and then sublimed, resulting in the separation of the waste into a dried solid material and liquid water. This technology is ideally suited to applications where water recovery rates approaching 100% are desirable but production of CO, is not. Water contained within solid wastes accounts for approximately 3% of the total water balance. If 100% closure of the water loop is desired the water contained within this waste would need to be recovered. To facilitate operation in microgravity thermoelectric heat pumps have be used in place of traditional fluid cycle heat pumps. A mathematical model of a thermoelectric lyophilizer has been developed and used to generate energy use and processing rate parameters. The results of laboratory investigations and discussions with ALS program management have been used to iteratively arrive at a prototype design. This design address operational limitations which were identified in the laboratory studies and handling and health concerns raised by ALS program management. The current prototype design is capable of integration into the ISS Waste Collection System.

High-performance shape-engineerable thermoelectric painting

PubMed Central

Park, Sung Hoon; Jo, Seungki; Kwon, Beomjin; Kim, Fredrick; Ban, Hyeong Woo; Lee, Ji Eun; Gu, Da Hwi; Lee, Se Hwa; Hwang, Younghun; Kim, Jin-Sang; Hyun, Dow-Bin; Lee, Sukbin; Choi, Kyoung Jin; Jo, Wook; Son, Jae Sung

2016-01-01

Output power of thermoelectric generators depends on device engineering minimizing heat loss as well as inherent material properties. However, the device engineering has been largely neglected due to the limited flat or angular shape of devices. Considering that the surface of most heat sources where these planar devices are attached is curved, a considerable amount of heat loss is inevitable. To address this issue, here, we present the shape-engineerable thermoelectric painting, geometrically compatible to surfaces of any shape. We prepared Bi2Te3-based inorganic paints using the molecular Sb2Te3 chalcogenidometalate as a sintering aid for thermoelectric particles, with ZT values of 0.67 for n-type and 1.21 for p-type painted materials that compete the bulk values. Devices directly brush-painted onto curved surfaces produced the high output power of 4.0 mW cm−2. This approach paves the way to designing materials and devices that can be easily transferred to other applications. PMID:27834369

Thermoelectricity for future sustainable energy technologies

NASA Astrophysics Data System (ADS)

Weidenkaff, Anke

2017-07-01

Thermoelectricity is a general term for a number of effects describing the direct interconversion of heat and electricity. Thermoelectric devices are therefore promising, environmental-friendly alternatives to conventional power generators or cooling units. Since the mid-90s, research on thermoelectric properties and their applications has steadily increased. In the course of years, the development of high-temperature resistant TE materials and devices has emerged as one of the main areas of interest focusing both on basic research and practical applications. A wide range of innovative and cost-efficient material classes has been studied and their properties improved. This has also led to advances in synthesis and metrology. The paper starts out with thermoelectric history, basic effects underlying thermoelectric conversion and selected examples of application. The main part focuses on thermoelectric materials including an outline of the design rules, a review on the most common materials and the feasibility of improved future high-temperature thermoelectric converters.

Opto-thermoelectric nanotweezers.

PubMed

Lin, Linhan; Wang, Mingsong; Peng, Xiaolei; Lissek, Emanuel N; Mao, Zhangming; Scarabelli, Leonardo; Adkins, Emily; Coskun, Sahin; Unalan, Husnu Emrah; Korgel, Brian A; Liz-Marzán, Luis M; Florin, Ernst-Ludwig; Zheng, Yuebing

2018-04-01

Optical manipulation of plasmonic nanoparticles provides opportunities for fundamental and technical innovation in nanophotonics. Optical heating arising from the photon-to-phonon conversion is considered as an intrinsic loss in metal nanoparticles, which limits their applications. We show here that this drawback can be turned into an advantage, by developing an extremely low-power optical tweezing technique, termed opto-thermoelectric nanotweezers (OTENT). Through optically heating a thermoplasmonic substrate, alight-directed thermoelectric field can be generated due to spatial separation of dissolved ions within the heating laser spot, which allows us to manipulate metal nanoparticles of a wide range of materials, sizes and shapes with single-particle resolution. In combination with dark-field optical imaging, nanoparticles can be selectively trapped and their spectroscopic response can be resolved in-situ . With its simple optics, versatile low-power operation, applicability to diverse nanoparticles, and tuneable working wavelength, OTENT will become a powerful tool in colloid science and nanotechnology.

Si Thermoelectric Power Generator with an Unconventional Structure

NASA Astrophysics Data System (ADS)

Sakamoto, Tatsuya; Iida, Tsutomu; Ohno, Yota; Ishikawa, Masashi; Kogo, Yasuo; Hirayama, Naomi; Arai, Koya; Nakamura, Takashi; Nishio, Keishi; Takanashi, Yoshifumi

2014-06-01

We examine the mechanical stability of an unconventional Mg2Si thermoelectric generator (TEG) structure. In this structure, the angle θ between the thermoelectric (TE) chips and the heat sink is less than 90°. We examined the tolerance to an external force of various Mg2Si TEG structures using a finite-element method (FEM) with the ANSYS code. The output power of the TEGs was also measured. First, for the FEM analysis, the mechanical properties of sintered Mg2Si TE chips, such as the bending strength and Young's modulus, were measured. Then, two-dimensional (2D) TEG models with various values of θ (90°, 75°, 60°, 45°, 30°, 15°, and 0°) were constructed in ANSYS. The x and y axes were defined as being in the horizontal and vertical directions of the substrate, respectively. In the analysis, the maximum tensile stress in the chip when a constant load was applied to the TEG model in the x direction was determined. Based on the analytical results, an appropriate structure was selected and a module fabricated. For the TEG fabrication, eight TE chips, each with dimensions of 3 mm × 3 mm × 10 mm and consisting of Sb-doped n-Mg2Si prepared by a plasma-activated sintering process, were assembled such that two chips were connected in parallel, and four pairs of these were connected in series on a footprint of 46 mm × 12 mm. The measured power generation characteristics and temperature distribution with temperature differences between 873 K and 373 K are discussed.

Magnesium and Manganese Silicides For Efficient And Low Cost Thermo-Electric Power Generation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Trivedi, Sudhir B.; Kutcher, Susan W.; Rosemeier, Cory A.

2013-12-02

Thermoelectric Power Generation (TEPG) is the most efficient and commercially deployable power generation technology for harvesting wasted heat from such things as automobile exhausts, industrial furnaces, and incinerators, and converting it into usable electrical power. We investigated the materials magnesium silicide (Mg2Si) and manganese silicide (MnSi) for TEG. MgSi2 and MnSi are environmentally friendly, have constituent elements that are abundant in the earth's crust, non-toxic, lighter and cheaper. In Phase I, we successfully produced Mg2Si and MnSi material with good TE properties. We developed a novel technique to synthesize Mg2Si with good crystalline quality, which is normally very difficult duemore » to high Mg vapor pressure and its corrosive nature. We produced n-type Mg2Si and p-type MnSi nanocomposite pellets using FAST. Measurements of resistivity and voltage under a temperature gradient indicated a Seebeck coefficient of roughly 120 V/K on average per leg, which is quite respectable. Results indicated however, that issues related to bonding resulted in high resistivity contacts. Determining a bonding process and bonding material that can provide ohmic contact from room temperature to the operating temperature is an essential part of successful device fabrication. Work continues in the development of a process for reproducibly obtaining low resistance electrical contacts.« less

Recent Development of Thermoelectric Polymers and Composites.

PubMed

Yao, Hongyan; Fan, Zeng; Cheng, Hanlin; Guan, Xin; Wang, Chen; Sun, Kuan; Ouyang, Jianyong

2018-03-01

Thermoelectric materials can be used as the active materials in thermoelectric generators and as Peltier coolers for direct energy conversion between heat and electricity. Apart from inorganic thermoelectric materials, thermoelectric polymers have been receiving great attention due to their unique advantages including low cost, high mechanical flexibility, light weight, low or no toxicity, and intrinsically low thermal conductivity. The power factor of thermoelectric polymers has been continuously rising, and the highest ZT value is more than 0.25 at room temperature. The power factor can be further improved by forming composites with nanomaterials. This article provides a review of recent developments on thermoelectric polymers and polymer composites. It focuses on the relationship between thermoelectric properties and the materials structure, including chemical structure, microstructure, dopants, and doping levels. Their thermoelectric properties can be further improved to be comparable to inorganic counterparts in the near future. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Universal thermoelectric unit

NASA Astrophysics Data System (ADS)

Fedorov, M. I.; Engalychev, A. E.; Zaitsev, V. K.; Kaliazin, A. E.; Solomkin, F. Yu.

1994-08-01

The problems of energy supply of low power electric devices very often can be solved with thermoelectric generator even with low coefficient of performance, when other electric energy sources are not convenient. The problems of thermoelectric and construction choice for such generators are discussed in the paper. A series of domestic thermoelectric generators was designed by the authors. The work is based on designing an universal thermoelectric unit—a battery which consist of ten thermoelements. The coefficient of performance of the unit is about 4%. Any thermoelectric generator can be made as a combination of these units. Principal opportunity of production such thermoelectric generators on industrial scale was proved.

Electronic structure of some complex thermoelectrics - role of dimensional confinement and nanostructuring

NASA Astrophysics Data System (ADS)

Mahanti, Subhendra D.; Hoang, Khang

2016-12-01

Thermoelectric materials are of great current interest for a number of energy-related applications such as waste heat recovery, terrestrial cooling, and thermoelectric power generation. There have been several significant recent advances in improving the thermoelectric figure of merit ZT; in some instances, ZT > 2 at high temperatures. Concepts like electron-crystal phonon-glass, dimensional confinement, nanostructuring, energy filtering, and intrinsic lattice anharmonicity have not only acted as guiding principles in synthesizing new materials but also for electronic structure engineering using theoretical calculations. In this review paper, we discuss these concepts and present a few examples of theoretical studies of electronic structure and transport properties illustrating how some of these ideas work. The four types of systems we discuss are quaternary chalcogenides LAST-m, nanoscale mixtures of half-Heusler and Heusler compounds, ternary chalcogenide compounds of type ABX2 where the electronic structure near the band gap depends sensitively on the ordering of A and B atoms, and naturally occurring bulk superlattices formed out of alternating ionic and semiconducting bilayers as in SrFAgTe.

Controls on water use for thermoelectric generation: case study Texas, US.

PubMed

Scanlon, Bridget R; Reedy, Robert C; Duncan, Ian; Mullican, William F; Young, Michael

2013-10-01

Large-scale U.S. dependence on thermoelectric (steam electric) generation requiring water for cooling underscores the need to understand controls on this water use. The study objective was to quantify water consumption and withdrawal for thermoelectric generation, identifying controls, using Texas as a case study. Water consumption for thermoelectricity in Texas in 2010 totaled ∼0.43 million acre feet (maf; 0.53 km(3)), accounting for ∼4% of total state water consumption. High water withdrawals (26.2 maf, 32.3 km(3)) mostly reflect circulation between ponds and power plants, with only two-thirds of this water required for cooling. Controls on water consumption include (1) generator technology/thermal efficiency and (2) cooling system, resulting in statewide consumption intensity for natural gas combined cycle generators with mostly cooling towers (0.19 gal/kWh) being 63% lower than that of traditional coal, nuclear, or natural gas steam turbine generators with mostly cooling ponds (0.52 gal/kWh). The primary control on water withdrawals is cooling system, with ∼2 orders of magnitude lower withdrawals for cooling towers relative to once-through ponds statewide. Increases in natural gas combined cycle plants with cooling towers in response to high production of low-cost natural gas has greatly reduced water demand for thermoelectric cooling since 2000.

Fabrication and Characterization of Bi2Te3-Based Chip-Scale Thermoelectric Energy Harvesting Devices

NASA Astrophysics Data System (ADS)

Cornett, Jane; Chen, Baoxing; Haidar, Samer; Berney, Helen; McGuinness, Pat; Lane, Bill; Gao, Yuan; He, Yifan; Sun, Nian; Dunham, Marc; Asheghi, Mehdi; Goodson, Ken; Yuan, Yi; Najafi, Khalil

2017-05-01

Thermoelectric energy harvesters convert otherwise wasted heat into electrical energy. As a result, they have the potential to play a critical role in the autonomous wireless sensor network signal chain. In this paper, we present work carried out on the development of Bi2Te3-based thermoelectric chip-scale energy harvesting devices. Process flow, device demonstration and characterization are highlighted.

A Solution Processable High-Performance Thermoelectric Copper Selenide Thin Film.

PubMed

Lin, Zhaoyang; Hollar, Courtney; Kang, Joon Sang; Yin, Anxiang; Wang, Yiliu; Shiu, Hui-Ying; Huang, Yu; Hu, Yongjie; Zhang, Yanliang; Duan, Xiangfeng

2017-06-01

A solid-state thermoelectric device is attractive for diverse technological areas such as cooling, power generation and waste heat recovery with unique advantages of quiet operation, zero hazardous emissions, and long lifetime. With the rapid growth of flexible electronics and miniature sensors, the low-cost flexible thermoelectric energy harvester is highly desired as a potential power supply. Herein, a flexible thermoelectric copper selenide (Cu 2 Se) thin film, consisting of earth-abundant elements, is reported. The thin film is fabricated by a low-cost and scalable spin coating process using ink solution with a truly soluble precursor. The Cu 2 Se thin film exhibits a power factor of 0.62 mW/(m K 2 ) at 684 K on rigid Al 2 O 3 substrate and 0.46 mW/(m K 2 ) at 664 K on flexible polyimide substrate, which is much higher than the values obtained from other solution processed Cu 2 Se thin films (<0.1 mW/(m K 2 )) and among the highest values reported in all flexible thermoelectric films to date (≈0.5 mW/(m K 2 )). Additionally, the fabricated thin film shows great promise to be integrated with the flexible electronic devices, with negligible performance change after 1000 bending cycles. Together, the study demonstrates a low-cost and scalable pathway to high-performance flexible thin film thermoelectric devices from relatively earth-abundant elements. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Potentialities of silicon nanowire forests for thermoelectric generation

NASA Astrophysics Data System (ADS)

Dimaggio, Elisabetta; Pennelli, Giovanni

2018-04-01

Silicon is a material with very good thermoelectric properties, with regard to Seebeck coefficient and electrical conductivity. Low thermal conductivities, and hence high thermal to electrical conversion efficiencies, can be achieved in nanostructures, which are smaller than the phonon mean free path but large enough to preserve the electrical conductivity. We demonstrate that it is possible to fabricate a leg of a thermoelectric generator based on large collections of long nanowires, placed perpendicularly to the two faces of a silicon wafer. The process exploits the metal assisted etching technique which is simple, low cost, and can be easily applied to large surfaces. Copper can be deposited by electrodeposition on both faces, so that contacts can be provided, on top of the nanowires. Thermal conductivity of silicon nanowire forests with more than 107 nanowires mm-2 have been measured; the result is comparable with that achieved by several groups on devices based on few nanowires. On the basis of the measured parameters, numerical calculations of the efficiency of silicon-based thermoelectric generators are reported, and the potentialities of these devices for thermal to electrical energy conversion are shown. Criteria to improve the conversion efficiency are suggested and described.

Fabrication of Bi–Sb–Te Thermoelectric by Cold-Pressed Sintering for Motorcycle Exhaust.

PubMed

Kao, Mu-Jung; Chen, Ming-Jing

2017-04-01

This study was conducted on the Bi–Sb–Te thermoelectric material which is cold-pressed Sintering under 750 Mpa to make square thermoelectric pairs with size 8.2 mm × 8.2 mm and thicknesses 0.8 mm and 1.5 mm. The zone melting method was used to acquire P-type thermoelectric material Bi0.4Sb1.6Te3 and N-type thermoelectric material Bi2Te2.5Se0.5. At temperature 383 K, the measured Seebeck coefficient of Bi0.4Sb1.6Te3 is 222 μV/K, and its thermoelectric figure of merit ZT is 1.35. At temperature 400 K, the measured Seebeck coefficient of Bi2Te2.5Se0.5 is 210 μV/K, and its thermoelectric figure of merit ZT is 1.13. Using Solder paste Sn42Bi58 and copper electrode plate are in series connection with 16 pieces of P/N thermoelectric material to form thermoelectric modules. The thermoelectric module is actually pasted on the motorcycle waste heat source to be evaluated the performance, making the cold-end temperature dissipation heat can enhance the temperature difference between it so as to increase the output power. Increasing the leg thickness of thermoelectric module and making the about 35 °C temperature-difference of those can obviously enhance the performance of in terms of its voltage, its thermoelectric figure of merit ZT and output power of the thermoelectric modules.

Revisiting Feynman's ratchet with thermoelectric transport theory.

PubMed

Apertet, Y; Ouerdane, H; Goupil, C; Lecoeur, Ph

2014-07-01

We show how the formalism used for thermoelectric transport may be adapted to Smoluchowski's seminal thought experiment, also known as Feynman's ratchet and pawl system. Our analysis rests on the notion of useful flux, which for a thermoelectric system is the electrical current and for Feynman's ratchet is the effective jump frequency. Our approach yields original insight into the derivation and analysis of the system's properties. In particular we define an entropy per tooth in analogy with the entropy per carrier or Seebeck coefficient, and we derive the analog to Kelvin's second relation for Feynman's ratchet. Owing to the formal similarity between the heat fluxes balance equations for a thermoelectric generator (TEG) and those for Feynman's ratchet, we introduce a distribution parameter γ that quantifies the amount of heat that flows through the cold and hot sides of both heat engines. While it is well established that γ = 1/2 for a TEG, it is equal to 1 for Feynman's ratchet. This implies that no heat may be rejected in the cold reservoir for the latter case. Further, the analysis of the efficiency at maximum power shows that the so-called Feynman efficiency corresponds to that of an exoreversible engine, with γ = 1. Then, turning to the nonlinear regime, we generalize the approach based on the convection picture and introduce two different types of resistance to distinguish the dynamical behavior of the considered system from its ability to dissipate energy. We finally put forth the strong similarity between the original Feynman ratchet and a mesoscopic thermoelectric generator with a single conducting channel.

Development of thermocouple generators for small-caliber munitions fuze. Phase I. Final report, 1 Feb--3 Sep 1974. [Aerodynamically heated thermoelectric converters to power rf proximity fuses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eggers, P.E.

1975-03-01

An analytical study has been performed to assess the feasibility of using aerodynamically heated thermoelectric convertors to power RF proximity fuzes. The collective results of this study indicate that such a thermoelectric power supply is feasible for use with 20 mm projectiles and is compatible with the existing RF fuze circuit and safe arming distance requirements. A disc module concept has evolved from this study involving thin-film bismuth telluride as the basic thermoelectric element. Preliminary experimental studies were completed in order to identify principal parameters for the bismuth telluride.

Designing, building, and testing a solar thermoelectric generation, STEG, for energy delivery to remote residential areas in developing regions

NASA Astrophysics Data System (ADS)

Moumouni, Yacouba

New alternatives and inventive renewable energy techniques which encompass both generation and power management solutions are fundamental for meeting remote residential energy supply and demand today, especially if the grid is quasi-inexistent. Solar thermoelectric generators can be a cost-effective alternative to photovoltaics for a remote residential household power supply. A complete solar thermoelectric energy harvesting system is presented for energy delivery to remote residential areas in developing regions. To this end, the entire system was built, modeled, and then validated with LTspice simulator software via thermal-to-electrical analogy schemes. Valuable data in conjunction with two novel LTspice circuits were obtained, showing the achievability of analyzing transient heat transfer with the Spice simulator. Hence, the proposed study begins with a comprehensive method of extracting thermal parameters that appear in thermoelectric modules. A step-by-step procedure was developed and followed to succinctly extract parameters, such as the Seebeck coefficient, electrical conductivity, thermal resistance, and thermal conductivity needed to model the system. Data extracted from datasheet, material properties, and geometries were successfully utilized to compute the thermal capacities and resistances necessary to perform the analogy. In addition, temperature variations of the intrinsic internal parameters were accounted for in this process for accuracy purposes. The steps that it takes to simulate any thermo-electrical system with the LTspice simulator are thoroughly explained in this work. As a consequence, an improved Spice model for a thermoelectric generator is proposed. Experimental results were compiled in the form of a lookup table and then fed into the Spice simulator using the piecewise linear (PWL) command in order to validate the model. Experimental results show that a temperature differential of 13.43°C was achievable whereas the simulation indicates

Molybdenum-platinum-oxide electrodes for thermoelectric generators

DOEpatents

Schmatz, Duane J.

1990-01-01

The invention is directed to a composite article suitable for use in thermoelectric generators. The article comprises a solid electrolyte carrying a thin film comprising molybdenum-platinum-oxide as an electrode deposited by physical deposition techniques. The invention is also directed to the method of making same.

Recent progress in thermoelectric nanocomposites based on solution-synthesized nanoheterostructures

DOE PAGES

Zheng, Wei; Xu, Biao; Zhou, Lin; ...

2017-03-27

Thermoelectric materials, which can convert waste heat into electricity, have received increasing interest in these years. This paper describes the recent progress in thermoelectric nanocomposite based on solution-synthesized nanoheterostructures. We start our discussion with the strategies of improving power factor of a given material by using nanoheterostructures. Then we discuss the methods of decreasing thermal conductivity. Finally, we highlight one way to decouple power factor and thermal conductivity, namely, incorporating phase-transition materials into a nanowire heterostructure. We have explored the lead telluride-copper telluride thermoelectric nanowire heterostructure in our group. Future possible ways to improve figure of merit are discussed atmore » the end of this paper.« less

Recent progress in thermoelectric nanocomposites based on solution-synthesized nanoheterostructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zheng, Wei; Xu, Biao; Zhou, Lin

Thermoelectric materials, which can convert waste heat into electricity, have received increasing interest in these years. This paper describes the recent progress in thermoelectric nanocomposite based on solution-synthesized nanoheterostructures. We start our discussion with the strategies of improving power factor of a given material by using nanoheterostructures. Then we discuss the methods of decreasing thermal conductivity. Finally, we highlight one way to decouple power factor and thermal conductivity, namely, incorporating phase-transition materials into a nanowire heterostructure. We have explored the lead telluride-copper telluride thermoelectric nanowire heterostructure in our group. Future possible ways to improve figure of merit are discussed atmore » the end of this paper.« less

Thermoelectric plastics: from design to synthesis, processing and structure–property relationships

PubMed Central

Kroon, Renee; Mengistie, Desalegn Alemu; Kiefer, David; Hynynen, Jonna; Ryan, Jason D.; Yu, Liyang

2016-01-01

Thermoelectric plastics are a class of polymer-based materials that combine the ability to directly convert heat to electricity, and vice versa, with ease of processing. Potential applications include waste heat recovery, spot cooling and miniature power sources for autonomous electronics. Recent progress has led to surging interest in organic thermoelectrics. This tutorial review discusses the current trends in the field with regard to the four main building blocks of thermoelectric plastics: (1) organic semiconductors and in particular conjugated polymers, (2) dopants and counterions, (3) insulating polymers, and (4) conductive fillers. The design and synthesis of conjugated polymers that promise to show good thermoelectric properties are explored, followed by an overview of relevant structure–property relationships. Doping of conjugated polymers is discussed and its interplay with processing as well as structure formation is elucidated. The use of insulating polymers as binders or matrices is proposed, which permit the adjustment of the rheological and mechanical properties of a thermoelectric plastic. Then, nanocomposites of conductive fillers such as carbon nanotubes, graphene and inorganic nanowires in a polymer matrix are introduced. A case study examines poly(3,4-ethylenedioxythiophene) (PEDOT) based materials, which up to now have shown the most promising thermoelectric performance. Finally, a discussion of the advantages provided by bulk architectures e.g. for wearable applications highlights the unique advantages that thermoelectric plastics promise to offer. PMID:27385496

System and method to improve the power output and longetivity of a radioisotope thermoelectric generator

DOEpatents

Mowery, Jr., Alfred L.

1993-01-01

By using the helium generated by the alpha emissions of a thermoelectric generator during space travel for cooling, the thermal degradation of the thermoelectric generator can be slowed. Slowing degradation allows missions to be longer with little additional expense or payload.

Electronic cooling using thermoelectric devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zebarjadi, M., E-mail: m.zebarjadi@rutgers.edu; Institute of Advanced Materials, Devices, and Nanotechnology, Rutgers University, Piscataway, New Jersey 08854

2015-05-18

Thermoelectric coolers or Peltier coolers are used to pump heat in the opposite direction of the natural heat flux. These coolers have also been proposed for electronic cooling, wherein the aim is to pump heat in the natural heat flux direction and from hot spots to the colder ambient temperature. In this manuscript, we show that for such applications, one needs to use thermoelectric materials with large thermal conductivity and large power factor, instead of the traditionally used high ZT thermoelectric materials. We further show that with the known thermoelectric materials, the active cooling cannot compete with passive cooling, andmore » one needs to explore a new set of materials to provide a cooling solution better than a regular copper heat sink. We propose a set of materials and directions for exploring possible materials candidates suitable for electronic cooling. Finally, to achieve maximum cooling, we propose to use thermoelectric elements as fins attached to copper blocks.« less

Thermoelectric Products

NASA Technical Reports Server (NTRS)

1988-01-01

Instead of bulky coils and compressors used in conventional refrigeration systems, UST design engineers drew on thermo-electric technology. UST's precision temperature chambers (PTC's) feature small thermoelectric modules that measure not much more than 1 square inch and operate on unique phenomenon of heat exchange. When electric current flows through specialized metallic crystals, heat is produced; when current direction is reversed cooling is produced.

Design, manufacturing and testing of a portable vaccine carrier box employing thermoelectric module and heat pipe.

PubMed

Putra, N

2009-01-01

Vaccination is a highly effective method and a cheap tool for preventing certain infectious diseases. Routine immunization programs protect most of the world's children from diseases that claim millions of lives each year. There are many practical problems impeding vaccine delivery, especially to maintain the cold chain system, which is the means for storing and transporting vaccines in a potent state from the manufacturer to the person being immunized at a temperature of 2-8 degrees C. The development of the solid state thermoelectric cooling system has permitted newly developed packages that are capable of meeting many requirements and applications where environmental concern, size, weight, performance and noise are an issue. This paper describes the development of a vaccine carrier box. A combination of a thermoelectric module and a heat pipe is used for the cooling system. The position of the heat pipe as a heat sink on the hot side of the thermoelectric module will enhance the thermoelectric performance. The minimum temperature in the cabin of the vaccine carrier box reached -10 degrees C, which indicates that the design of the vaccine carrier box can maintain the vaccine at desired temperatures.

Thermoelectric properties of an interacting quantum dot based heat engine

NASA Astrophysics Data System (ADS)

Erdman, Paolo Andrea; Mazza, Francesco; Bosisio, Riccardo; Benenti, Giuliano; Fazio, Rosario; Taddei, Fabio

2017-06-01

We study the thermoelectric properties and heat-to-work conversion performance of an interacting, multilevel quantum dot (QD) weakly coupled to electronic reservoirs. We focus on the sequential tunneling regime. The dynamics of the charge in the QD is studied by means of master equations for the probabilities of occupation. From here we compute the charge and heat currents in the linear response regime. Assuming a generic multiterminal setup, and for low temperatures (quantum limit), we obtain analytical expressions for the transport coefficients which account for the interplay between interactions (charging energy) and level quantization. In the case of systems with two and three terminals we derive formulas for the power factor Q and the figure of merit Z T for a QD-based heat engine, identifying optimal working conditions which maximize output power and efficiency of heat-to-work conversion. Beyond the linear response we concentrate on the two-terminal setup. We first study the thermoelectric nonlinear coefficients assessing the consequences of large temperature and voltage biases, focusing on the breakdown of the Onsager reciprocal relation between thermopower and Peltier coefficient. We then investigate the conditions which optimize the performance of a heat engine, finding that in the quantum limit output power and efficiency at maximum power can almost be simultaneously maximized by choosing appropriate values of electrochemical potential and bias voltage. At last we study how energy level degeneracy can increase the output power.

Development of n-type cobaltocene-encapsulated carbon nanotubes with remarkable thermoelectric property

PubMed Central

Fukumaru, Takahiro; Fujigaya, Tsuyohiko; Nakashima, Naotoshi

2015-01-01

Direct conversion from heat to electricity is one of the important technologies for a sustainable society since large quantities of energy are wasted as heat. We report the development of a single-walled carbon nanotube (SWNT)-based high conversion efficiency, air-stable and flexible thermoelectric material. We prepared cobaltocene-encapsulated SWNTs (denoted CoCp2@SWNTs) and revealed that the material showed a negative-type (n-type) semiconducting behaviour (Seebeck coefficient: −41.8 μV K−1 at 320 K). The CoCp2@SWNT film was found to show a high electrical conductivity (43,200 S m−1 at 320 K) and large power factor (75.4 μW m−1 K−2) and the performance was remarkably stable under atmospheric conditions over a wide range of temperatures. The thermoelectric figure of merit (ZT) value of the CoCp2@SWNT film (0.157 at 320 K) was highest among the reported n-type organic thermoelectric materials due to the large power factor and low thermal conductivity (0.15 W m−1 K−1). These characteristics of the n-type CoCp2@SWNTs allowed us to fabricate a p-n type thermoelectric device by combination with an empty SWNT-based p-type film. The fabricated device exhibited a highly efficient power generation close to the calculated values even without any air-protective coating due to the high stability of the SWNT-based materials under atmospheric conditions. PMID:25608478

Silicon nanowire arrays as thermoelectric material for a power microgenerator

NASA Astrophysics Data System (ADS)

Dávila, D.; Tarancón, A.; Fernández-Regúlez, M.; Calaza, C.; Salleras, M.; San Paulo, A.; Fonseca, L.

2011-10-01

A novel design of a silicon-based thermoelectric power microgenerator is presented in this work. Arrays of silicon nanowires, working as thermoelectric material, have been integrated in planar uni-leg thermocouple microstructures to convert waste heat into electrical energy. Homogeneous, uniformly dense, well-oriented and size-controlled arrays of silicon nanowires have been grown by chemical vapor deposition using the vapor-liquid-solid mechanism. Compatibility issues between the nanowire growth method and microfabrication techniques, such as electrical contact patterning, are discussed. Electrical measurements of the nanowire array electrical conductivity and the Seebeck voltage induced by a controlled thermal gradient or under harvesting operation mode have been carried out to demonstrate the feasibility of the microdevice. A resistance of 240 Ω at room temperature was measured for an array of silicon nanowires 10 µm -long, generating a Seebeck voltage of 80 mV under an imposed thermal gradient of 450 °C, whereas only 4.5 mV were generated under a harvesting operation mode. From the results presented, a Seebeck coefficient of about 150-190 µV K-1 was estimated, which corresponds to typical values for bulk silicon.

Sources and potential application of waste heat utilization at a gas processing facility

NASA Astrophysics Data System (ADS)

Alshehhi, Alyas Ali

Waste heat recovery (WHR) has the potential to significantly improve the efficiency of oil and gas plants, chemical and other processing facilities, and reduce their environmental impact. In this Thesis a comprehensive energy audit at Abu Dhabi Gas Industries Ltd. (GASCO) ASAB gas processing facilities is undertaken to identify sources of waste heat and evaluate their potential for on-site recovery. Two plants are considered, namely ASAB0 and ASAB1. Waste heat evaluation criteria include waste heat grade (i.e., temperature), rate, accessibility (i.e., proximity) to potential on-site waste heat recovery applications, and potential impact of recovery on installation performance and safety. The operating parameters of key waste heat source producing equipment are compiled, as well as characteristics of the waste heat streams. In addition, potential waste heat recovery applications and strategies are proposed, focusing on utilities, i.e., enhancement of process cooling/heating, electrical/mechanical power generation, and steam production. The sources of waste heat identified at ASAB facilities consist of gas turbine and gas generator exhaust gases, flared gases, excess propane cooling capacity, excess process steam, process gas air-cooler heat dissipation, furnace exhaust gases and steam turbine outlet steam. Of the above waste heat sources, exhaust gases from five gas turbines and one gas generator at ASAB0 plant, as well as from four gas turbines at ASAB1 plant, were found to meet the rate (i.e., > 1 MW), grade (i.e., > 180°C), accessibility (i.e., < 50 m from potential on-site WHR applications) and minimal impact criteria on the performance and safety of existing installations, for potential waste heat recovery. The total amount of waste heat meeting these criteria were estimated at 256 MW and 289 MW at ASAB0 and ASAB1 plants, respectively, both of which are substantial. Of the 289 MW waste generated at ASAB1, approximately 173 MW are recovered by waste heat

Calibration of High Temperature Thermal Conductivity System: New Algorithm to Measure Heat Capacity Using Flash Thermal Diffusivity in Thermoelectric Materials

NASA Technical Reports Server (NTRS)

Deb, Rahul; Snyder, Jeff G.

2005-01-01

A viewgraph presentation describing thermoelectric materials, an algorithm for heat capacity measurements and the process of flash thermal diffusivity. The contents include: 1) What are Thermoelectrics?; 2) Thermoelectric Applications; 3) Improving Thermoelectrics; 4) Research Goal; 5) Flash Thermal Diffusivity; 6) Background Effects; 7) Stainless Steel Comparison; 8) Pulse Max Integral; and 9) Graphite Comparison Algorithm.

A Low-Cost Production Method of FeSi2 Power Generation Thermoelectric Modules

NASA Astrophysics Data System (ADS)

Inoue, Hiroyuki; Kobayashi, Takahide; Kato, Masahiko; Yoneda, Seiji

2016-03-01

A method is proposed to reduce the production cost of power generation thermoelectric modules. FeSi2 is employed as the thermoelectric material because of its low cost, low environmental load, and oxidation resistance. The raw materials were prepared in the composition of Fe0.96Si2.1Co0.04 for n-type and Fe0.92Si2.1Mn0.08 for p-type, which were added with 0.5 wt.% Cu as the starting materials. They were sintered without pressure at 1446 K to be formed into elements. The Seebeck coefficient and resistivity at room temperature were determined to be -182 μV/K and 0.13 mΩm for n-type, and 338 μV/K and 1.13 mΩm for p-type, respectively. The brazing conditions of the direct joining between the element and the solder were examined. Pastes of BNi-6, BNi-7 or TB-608T were tried as the solder. TB-608T was useable for metallizing of insulation substrates and joining of thermoelectric elements in order to manufacture thermoelectric modules. The joining strength was determined to be 50 MPa between the alumina plate and the elements. No mechanical failure was observed in the modules after repetition of 10 or more exposures to a heat source of 670 K. No change was found in the internal resistance. The present production method will provide modules with high durability and low production cost, which will enable high-power multi-stage cascade modules at a reasonable cost.

Mixed, charge and heat noises in thermoelectric nanosystems

NASA Astrophysics Data System (ADS)

Crépieux, Adeline; Michelini, Fabienne

2015-01-01

Mixed, charge and heat current fluctuations as well as thermoelectric differential conductances are considered for non-interacting nanosystems connected to reservoirs. Using the Landauer-Büttiker formalism, we derive general expressions for these quantities and consider their possible relationships in the entire ranges of temperature, voltage and coupling to the environment or reservoirs. We introduce a dimensionless quantity given by the ratio between the product of mixed noises and the product of charge and heat noises, distinguishing between the auto-ratio defined in the same reservoir and the cross-ratio between distinct reservoirs. From the linear response regime to the high-voltage regime, we further specify the analytical expressions of differential conductances, noises and ratios of noises, and examine their behavior in two concrete nanosystems: a quantum point contact in an ohmic environment and a single energy level quantum dot connected to reservoirs. In the linear response regime, we find that these ratios are equal to each other and are simply related to the figure of merit. They can be expressed in terms of differential conductances with the help of the fluctuation-dissipation theorem. In the non-linear regime, these ratios radically distinguish between themselves as the auto-ratio remains bounded by one, while the cross-ratio exhibits rich and complex behaviors. In the quantum dot nanosystem, we moreover demonstrate that the thermoelectric efficiency can be expressed as a ratio of noises in the non-linear Schottky regime. In the intermediate voltage regime, the cross-ratio changes sign and diverges, which evidences a change of sign in the heat cross-noise.

Mixed, charge and heat noises in thermoelectric nanosystems.

PubMed

Crépieux, Adeline; Michelini, Fabienne

2015-01-14

Mixed, charge and heat current fluctuations as well as thermoelectric differential conductances are considered for non-interacting nanosystems connected to reservoirs. Using the Landauer-Büttiker formalism, we derive general expressions for these quantities and consider their possible relationships in the entire ranges of temperature, voltage and coupling to the environment or reservoirs. We introduce a dimensionless quantity given by the ratio between the product of mixed noises and the product of charge and heat noises, distinguishing between the auto-ratio defined in the same reservoir and the cross-ratio between distinct reservoirs. From the linear response regime to the high-voltage regime, we further specify the analytical expressions of differential conductances, noises and ratios of noises, and examine their behavior in two concrete nanosystems: a quantum point contact in an ohmic environment and a single energy level quantum dot connected to reservoirs. In the linear response regime, we find that these ratios are equal to each other and are simply related to the figure of merit. They can be expressed in terms of differential conductances with the help of the fluctuation-dissipation theorem. In the non-linear regime, these ratios radically distinguish between themselves as the auto-ratio remains bounded by one, while the cross-ratio exhibits rich and complex behaviors. In the quantum dot nanosystem, we moreover demonstrate that the thermoelectric efficiency can be expressed as a ratio of noises in the non-linear Schottky regime. In the intermediate voltage regime, the cross-ratio changes sign and diverges, which evidences a change of sign in the heat cross-noise.

Accumulation and subsequent utilization of waste heat

NASA Astrophysics Data System (ADS)

Koloničný, Jan; Richter, Aleš; Pavloková, Petra

2016-06-01

This article aims to introduce a special way of heat accumulation and primary operating characteristics. It is the unique way in which the waste heat from flue gas of biogas cogeneration station is stored in the system of storage tanks, into the heat transfer oil. Heat is subsequently transformed into water, from which is generated the low-pressure steam. Steam, at the time of peak electricity needs, spins the special designed turbine generator and produces electrical energy.

Controls on Water Use for Thermoelectric Generation: Case Study Texas, U.S.

PubMed Central

2013-01-01

Large-scale U.S. dependence on thermoelectric (steam electric) generation requiring water for cooling underscores the need to understand controls on this water use. The study objective was to quantify water consumption and withdrawal for thermoelectric generation, identifying controls, using Texas as a case study. Water consumption for thermoelectricity in Texas in 2010 totaled ∼0.43 million acre feet (maf; 0.53 km3), accounting for ∼4% of total state water consumption. High water withdrawals (26.2 maf, 32.3 km3) mostly reflect circulation between ponds and power plants, with only two-thirds of this water required for cooling. Controls on water consumption include (1) generator technology/thermal efficiency and (2) cooling system, resulting in statewide consumption intensity for natural gas combined cycle generators with mostly cooling towers (0.19 gal/kWh) being 63% lower than that of traditional coal, nuclear, or natural gas steam turbine generators with mostly cooling ponds (0.52 gal/kWh). The primary control on water withdrawals is cooling system, with ∼2 orders of magnitude lower withdrawals for cooling towers relative to once-through ponds statewide. Increases in natural gas combined cycle plants with cooling towers in response to high production of low-cost natural gas has greatly reduced water demand for thermoelectric cooling since 2000. PMID:23937226

Test and evaluation of the Navy half-watt RTG. [Radioisotope Thermoelectric Generator

NASA Technical Reports Server (NTRS)

Rosell, F. E., Jr.; Lane, S. D.; Eggers, P. E.; Gawthrop, W. E.; Rouklove, P. G.; Truscello, V. C.

1976-01-01

The radioisotope thermoelectric generator (RTG) considered is to provide a continuous minimum power output of 0.5 watt at 6.0 to 8.5 volts for a minimum period of 15 years. The mechanical-electrical evaluation phase discussed involved the conduction of shock and vibration tests. The thermochemical-physical evaluation phase consisted of an analysis of the materials and the development of a thermal model. The thermoelectric evaluation phase included the accelerated testing of the thermoelectric modules.

Metallic Junction Thermoelectric Device Simulations

NASA Technical Reports Server (NTRS)

Duzik, Adam J.; Choi, Sang H.

2017-01-01

Thermoelectric junctions made of semiconductors have existed in radioisotope thermoelectric generators (RTG) for deep space missions, but are currently being adapted for terrestrial energy harvesting. Unfortunately, these devices are inefficient, operating at only 7% efficiency. This low efficiency has driven efforts to make high-figure-of-merit thermoelectric devices, which require a high electrical conductivity but a low thermal conductivity, a combination that is difficult to achieve. Lowered thermal conductivity has increased efficiency, but at the cost of power output. An alternative setup is to use metallic junctions rather than semiconductors as thermoelectric devices. Metals have orders of magnitude more electrons and electronic conductivities higher than semiconductors, but thermal conductivity is higher as well. To evaluate the viability of metallic junction thermoelectrics, a two dimensional heat transfer MATLAB simulation was constructed to calculate efficiency and power output. High Seebeck coefficient alloys, Chromel (90%Ni-10%Cr) and Constantan (55%Cu-45%Ni), produced efficiencies of around 20-30%. Parameters such as the number of layers of junctions, lateral junction density, and junction sizes for both series- and parallel-connected junctions were explored.

Effect of Cooling Units on the Performance of an Automotive Exhaust-Based Thermoelectric Generator

NASA Astrophysics Data System (ADS)

Su, C. Q.; Zhu, D. C.; Deng, Y. D.; Wang, Y. P.; Liu, X.

2017-05-01

Currently, automotive exhaust-based thermoelectric generators (AETEGs) are a hot topic in energy recovery. In order to investigate the influence of coolant flow rate, coolant flow direction and cooling unit arrangement in the AETEG, a thermoelectric generator (TEG) model and a related test bench are constructed. Water cooling is adopted in this study. Due to the non-uniformity of the surface temperature of the heat source, the coolant flow direction would affect the output performance of the TEG. Changing the volumetric flow rate of coolant can increase the output power of multi-modules connected in series or/and parallel as it can improve the temperature uniformity of the cooling unit. Since the temperature uniformity of the cooling unit has a strong influence on the output power, two cooling units are connected in series or parallel to research the effect of cooling unit arrangements on the maximum output power of the TEG. Experimental and theoretical analyses reveal that the net output power is generally higher with cooling units connected in parallel than cooling units connected in series in the cooling system with two cooling units.

Mechanical Signature of Heat Generated in a Current-Driven Ferromagnetic Resonance System

NASA Astrophysics Data System (ADS)

Cho, Sung Un; Jo, Myunglae; Park, Seondo; Lee, Jae-Hyun; Yang, Chanuk; Kang, Seokwon; Park, Yun Daniel

2017-07-01

In a current-driven ferromagnetic resonance (FMR) system, heat generated by time-dependent magnetoresistance effects, caused by magnetization precession, cannot be overlooked. Here, we describe the generated heat by magnetization motion under electric current in a freestanding nanoelectromechanical resonator fashioned from a permalloy (Py )/Pt bilayer. By piezoresistive transduction of Pt, the mechanical mode is electrically detected at room temperature and the internal heat in Py excluding thermoelectric effects is quantified as a shift of the mechanical resonance. We find that the measured spectral shifts correspond to the FMR, which is further verified from the spin-torque FMR measurement. Furthermore, the angular dependence of the mechanical reaction on an applied magnetic field reveals that the full accounting of FMR heat dissipation requires the time-dependent magnetoresistance effect.

Power Generator with Thermo-Differential Modules

NASA Technical Reports Server (NTRS)

Saiz, John R.; Nguyen, James

2010-01-01

A thermoelectric power generator consists of an oven box and a solar cooker/solar reflector unit. The solar reflector concentrates sunlight into heat and transfers the heat into the oven box via a heat pipe. The oven box unit is surrounded by five thermoelectric modules and is located at the bottom end of the solar reflector. When the heat is pumped into one side of the thermoelectric module and ejected from the opposite side at ambient temperatures, an electrical current is produced. Typical temperature accumulation in the solar reflector is approximately 200 C (392 F). The heat pipe then transfers heat into the oven box with a loss of about 40 percent. At the ambient temperature of about 20 C (68 F), the temperature differential is about 100 C (180 F) apart. Each thermoelectric module, generates about 6 watts of power. One oven box with five thermoelectric modules produces about 30 watts. The system provides power for unattended instruments in remote areas, such as space colonies and space vehicles, and in polar and other remote regions on Earth.

Model for Increasing the Power Obtained from a Thermoelectric Generator Module

NASA Astrophysics Data System (ADS)

Huang, Gia-Yeh; Hsu, Cheng-Ting; Yao, Da-Jeng

2014-06-01

We have developed a model for finding the most efficient way of increasing the power obtained from a thermoelectric generator (TEG) module with a variety of operating conditions and limitations. The model is based on both thermoelectric principles and thermal resistance circuits, because a TEG converts heat into electricity consistent with these two theories. It is essential to take into account thermal contact resistance when estimating power generation. Thermal contact resistance causes overestimation of the measured temperature difference between the hot and cold sides of a TEG in calculation of the theoretical power generated, i.e. the theoretical power is larger than the experimental power. The ratio of the experimental open-loop voltage to the measured temperature difference, the effective Seebeck coefficient, can be used to estimate the thermal contact resistance in the model. The ratio of the effective Seebeck coefficient to the theoretical Seebeck coefficient, the Seebeck coefficient ratio, represents the contact conditions. From this ratio, a relationship between performance and different variables can be developed. The measured power generated by a TEG module (TMH400302055; Wise Life Technology, Taiwan) is consistent with the result obtained by use of the model; the relative deviation is 10%. Use of this model to evaluate the most efficient means of increasing the generated power reveals that the TEG module generates 0.14 W when the temperature difference is 25°C and the Seebeck coefficient ratio is 0.4. Several methods can be used triple the amount of power generated. For example, increasing the temperature difference to 43°C generates 0.41 W power; improving the Seebeck coefficient ratio to 0.65 increases the power to 0.39 W; simultaneously increasing the temperature difference to 34°C and improving the Seebeck coefficient ratio to 0.5 increases the power to 0.41 W. Choice of the appropriate method depends on the limitations of system, the cost, and

Compact thermoelectric converter systems technology

NASA Technical Reports Server (NTRS)

1973-01-01

A schematic of the developed tubular thermoelectric module is shown. It consists of alternate washers of n- and p-type lead telluride, separated by thin natural mica washers. Electrical continuity within the circuit is accomplished by cylindrical conductor rings located at the I.D. and O.D. of the lead telluride washers. The conductor rings are also separated by the same mica which separate the lead telluride washers. The result is a radially serpentine current path along the length of the module. The circuit is isolated from the structural claddings by thin sleeves of boron nitride. Circuit containment and heat transfer surfaces are provided by the inner and outer cladding, heat being transferred from a heat source at the inner clad, conducted radially outward through the lead telluride to the outer clad where the waste heat is removed by a heat rejection system.

High-efficiency photovoltaic technology including thermoelectric generation

NASA Astrophysics Data System (ADS)

Fisac, Miguel; Villasevil, Francesc X.; López, Antonio M.

2014-04-01

Nowadays, photovoltaic solar energy is a clean and reliable source for producing electric power. Most photovoltaic systems have been designed and built up for use in applications with low power requirements. The efficiency of solar cells is quite low, obtaining best results in monocrystalline silicon structures, with an efficiency of about 18%. When temperature rises, photovoltaic cell efficiency decreases, given that the short-circuit current is slightly increased, and the open-circuit voltage, fill factor and power output are reduced. To ensure that this does not affect performance, this paper describes how to interconnect photovoltaic and thermoelectric technology into a single structure. The temperature gradient in the solar panel is used to supply thermoelectric cells, which generate electricity, achieving a positive contribution to the total balance of the complete system.

Clean Power Generation from the Intractable Natural Coalfield Fires: Turn Harm into Benefit.

PubMed

Shi, Bobo; Su, Hetao; Li, Jinshi; Qi, Haining; Zhou, Fubao; Torero, José L; Chen, Zhongwei

2017-07-13

The coal fires, a global catastrophe for hundreds of years, have been proved extremely difficult to control, and hit almost every coal-bearing area globally. Meanwhile, underground coal fires contain tremendous reservoir of geothermal energy. Approximately one billion tons of coal burns underground annually in the world, which could generate ~1000 GW per annum. A game-changing approach, environmentally sound thermal energy extraction from the intractable natural coalfield fires, is being developed by utilizing the waste energy and reducing the temperature of coalfield fires at the same time. Based on the Seebeck effect of thermoelectric materials, the temperature difference between the heat medium and cooling medium was employed to directly convert thermal energy into clean electrical energy. By the time of December 2016, the power generation from a single borehole at Daquan Lake fire district in Xinjiang has been exceeded 174.6 W. The field trial demonstrates that it is possible to exploit and utilize the waste heat resources in the treated coal fire areas. It promises a significant impact on the structure of global energy generation and can also promote progress in thermoelectric conversion materials, geothermal exploration, underground coal fires control and other energy related areas.

Scalable Nernst thermoelectric power using a coiled galfenol wire

NASA Astrophysics Data System (ADS)

Yang, Zihao; Codecido, Emilio A.; Marquez, Jason; Zheng, Yuanhua; Heremans, Joseph P.; Myers, Roberto C.

2017-09-01

The Nernst thermopower usually is considered far too weak in most metals for waste heat recovery. However, its transverse orientation gives it an advantage over the Seebeck effect on non-flat surfaces. Here, we experimentally demonstrate the scalable generation of a Nernst voltage in an air-cooled metal wire coiled around a hot cylinder. In this geometry, a radial temperature gradient generates an azimuthal electric field in the coil. A Galfenol (Fe0.85Ga0.15) wire is wrapped around a cartridge heater, and the voltage drop across the wire is measured as a function of axial magnetic field. As expected, the Nernst voltage scales linearly with the length of the wire. Based on heat conduction and fluid dynamic equations, finite-element method is used to calculate the temperature gradient across the Galfenol wire and determine the Nernst coefficient. A giant Nernst coefficient of -2.6 μV/KT at room temperature is estimated, in agreement with measurements on bulk Galfenol. We expect that the giant Nernst effect in Galfenol arises from its magnetostriction, presumably through enhanced magnon-phonon coupling. Our results demonstrate the feasibility of a transverse thermoelectric generator capable of scalable output power from non-flat heat sources.

Apparatus for the measurement of electrical resistivity, Seebeck coefficient, and thermal conductivity of thermoelectric materials between 300 K and 12 K

NASA Astrophysics Data System (ADS)

Martin, Joshua; Nolas, George S.

2016-01-01

We have developed a custom apparatus for the consecutive measurement of the electrical resistivity, the Seebeck coefficient, and the thermal conductivity of materials between 300 K and 12 K. These three transport properties provide for a basic understanding of the thermal and electrical properties of materials. They are of fundamental importance in identifying and optimizing new materials for thermoelectric applications. Thermoelectric applications include waste heat recovery for automobile engines and industrial power generators, solid-state refrigeration, and remote power generation for sensors and space probes. The electrical resistivity is measured using a four-probe bipolar technique, the Seebeck coefficient is measured using the quasi-steady-state condition of the differential method in a 2-probe arrangement, and the thermal conductivity is measured using a longitudinal, multiple gradient steady-state technique. We describe the instrumentation and the measurement uncertainty associated with each transport property, each of which is presented with representative measurement comparisons using round robin samples and/or certified reference materials. Transport properties data from this apparatus have supported the identification, development, and phenomenological understanding of novel thermoelectric materials.

Oxide Thermoelectric Materials: A Structure-Property Relationship

NASA Astrophysics Data System (ADS)

Nag, Abanti; Shubha, V.

2014-04-01

Recent demand for thermoelectric materials for power harvesting from automobile and industrial waste heat requires oxide materials because of their potential advantages over intermetallic alloys in terms of chemical and thermal stability at high temperatures. Achievement of thermoelectric figure of merit equivalent to unity ( ZT ≈ 1) for transition-metal oxides necessitates a second look at the fundamental theory on the basis of the structure-property relationship giving rise to electron correlation accompanied by spin fluctuation. Promising transition-metal oxides based on wide-bandgap semiconductors, perovskite and layered oxides have been studied as potential candidate n- and p-type materials. This paper reviews the correlation between the crystal structure and thermoelectric properties of transition-metal oxides. The crystal-site-dependent electronic configuration and spin degeneracy to control the thermopower and electron-phonon interaction leading to polaron hopping to control electrical conductivity is discussed. Crystal structure tailoring leading to phonon scattering at interfaces and nanograin domains to achieve low thermal conductivity is also highlighted.

Thermoelectric efficiency of (1 - x)(GeTe) x(Bi2Se0.2Te2.8) and implementation into highly performing thermoelectric power generators.

PubMed

Koenig, J; Winkler, M; Dankwort, T; Hansen, A-L; Pernau, H-F; Duppel, V; Jaegle, M; Bartholomé, K; Kienle, L; Bensch, W

2015-02-14

Here we report for the first time on a complete simulation assisted "material to module" development of a high performance thermoelectric generator (TEG) based on the combination of a phase change material and established thermoelectrics yielding the compositions (1 - x)(GeTe) x(Bi(2)Se(0.2)Te(2.8)). For the generator design our approach for benchmarking thermoelectric materials is demonstrated which is not restricted to the determination of the intrinsically imprecise ZT value but includes the implementation of the material into a TEG. This approach is enabling a much more reliable benchmarking of thermoelectric materials for TEG application. Furthermore we analyzed the microstructure and performance close to in-operandi conditions for two different compositions in order to demonstrate the sensitivity of the material against processing and thermal cycling. For x = 0.038 the microstructure of the as-prepared material remains unchanged, consequently, excellent and stable thermoelectric performance as prerequisites for TEG production was obtained. For x = 0.063 we observed strain phenomena for the pristine state which are released by the formation of planar defects after thermal cycling. Consequently the thermoelectric performance degrades significantly. These findings highlight a complication for deriving the correlation of microstructure and properties of thermoelectric materials in general.

Insight into mechanical properties and thermoelectric efficiency of Zr2CoZ (Z  =  Si, Ge) Heusler alloys

NASA Astrophysics Data System (ADS)

Yousuf, Saleem; Gupta, Dinesh C.

2017-11-01

We investigated the electronic, mechanical and thermoelectric properties of Zr2CoZ (Z  =  Si, Ge) Heusler alloys using the first-principles calculation. From the analysis of various elastic constants, the shear and Young’s moduli, Poisson’s ratio, the ductile nature of the alloys is predicted. Thermoelectric coefficients viz., Seebeck, electrical conductivity and figure of merit show Zr2CoZ alloys as n-type thermoelectric materials showing linearly increasing Seebeck coefficient with temperature. The value of total absolute Seebeck coefficients at 1200 K of Zr2CoSi and Zr2CoGe are 60 µV K-1 and 40 µV K-1 respectively mainly because of the existence of almost flat conduction bands along L to Г directions of high symmetry Brillouin zone. Further, the chemical potential variation of power factor confirms the n-type doping fruitful to increase their TE performance. The figure of merit achieves an upper-limit of 0.95 at 850 K and can favour their use for waste heat recovery at higher temperatures and thermoelectric spin generators.

Crystal Lattice Controlled SiGe Thermoelectric Materials with High Figure of Merit

NASA Technical Reports Server (NTRS)

Kim, Hyun-Jung; Park, Yeonjoon; King, Glen C.; Lee, Kunik; Choi, Sang H.

2010-01-01

Direct energy conversion between thermal and electrical energy, based on thermoelectric (TE) effect, has the potential to recover waste heat and convert it to provide clean electric power. The energy conversion efficiency is related to the thermoelectric figure of merit ZT expressed as ZT=S(exp 2)(sigma)T/Kappa, T is temperature, S is the Seebeck coefficient, sigma is conductance and Kappa is thermal conductivity. For a lower thermal conductivity Kappa and high power factor (S(exp 2)(sigma)), our current strategy is the development of rhombohedrally strained single crystalline SiGe materials that are highly [111]-oriented twinned. The development of a SiGe "twin lattice structure (TLS)" plays a key role in phonon scattering. The TLS increases the electrical conductivity and decreases thermal conductivity due to phonon scattering at stacking faults generated from the 60 X rotated primary twin structure. To develop high performance materials, the substrate temperature, chamber working pressure, and DC sputtering power are controlled for the aligned growth production of SiGe layer and TLS on a c-plane sapphire. Additionally, a new elevated temperature thermoelectric characterization system, that measures the thermal diffusivity and Seebeck effect nondestructively, was developed. The material properties were characterized at various temperatures and optimized process conditions were experimentally determined. The present paper encompasses the technical discussions toward the development of thermoelectric materials and the measurement techniques.

Thermoelectric integrated membrane evaporation water recovery technology

NASA Technical Reports Server (NTRS)

Roebelen, G. J., Jr.; Winkler, H. E.; Dehner, G. F.

1982-01-01

The recently developed Thermoelectric Integrated Membrane Evaporation Subsystem (TIMES) offers a highly competitive approach to water recovery from waste fluids for future on-orbit stations such as the Space Operations Center. Low power, compactness and gravity insensitive operation are featured in this vacuum distillation subsystem that combines a hollow fiber membrane evaporator with a thermoelectric heat pump. The hollow fiber elements provide positive liquid/gas phase control with no moving parts other than pumps and an accumulator, thus solving problems inherent in other reclamation subsystem designs. In an extensive test program, over 850 hours of operation were accumulated during which time high quality product water was recovered from both urine and wash water at an average steady state production rate of 2.2 pounds per hour.

An approach to design a 90Sr radioisotope thermoelectric generator using analytical and Monte Carlo methods with ANSYS, COMSOL, and MCNP.

PubMed

Khajepour, Abolhasan; Rahmani, Faezeh

2017-01-01

In this study, a 90 Sr radioisotope thermoelectric generator (RTG) with power of milliWatt was designed to operate in the determined temperature (300-312K). For this purpose, the combination of analytical and Monte Carlo methods with ANSYS and COMSOL software as well as the MCNP code was used. This designed RTG contains 90 Sr as a radioisotope heat source (RHS) and 127 coupled thermoelectric modules (TEMs) based on bismuth telluride. Kapton (2.45mm in thickness) and Cryotherm sheets (0.78mm in thickness) were selected as the thermal insulators of the RHS, as well as a stainless steel container was used as a generator chamber. The initial design of the RHS geometry was performed according to the amount of radioactive material (strontium titanate) as well as the heat transfer calculations and mechanical strength considerations. According to the Monte Carlo simulation performed by the MCNP code, approximately 0.35 kCi of 90 Sr is sufficient to generate heat power in the RHS. To determine the optimal design of the RTG, the distribution of temperature as well as the dissipated heat and input power to the module were calculated in different parts of the generator using the ANSYS software. Output voltage according to temperature distribution on TEM was calculated using COMSOL. Optimization of the dimension of the RHS and heat insulator was performed to adapt the average temperature of the hot plate of TEM to the determined hot temperature value. This designed RTG generates 8mW in power with an efficiency of 1%. This proposed approach of combination method can be used for the precise design of various types of RTGs. Copyright © 2016 Elsevier Ltd. All rights reserved.

Thermoelectric Generation Using Counter-Flows of Ideal Fluids

NASA Astrophysics Data System (ADS)

Meng, Xiangning; Lu, Baiyi; Zhu, Miaoyong; Suzuki, Ryosuke O.

2017-08-01

Thermoelectric (TE) performance of a three-dimensional (3-D) TE module is examined by exposing it between a pair of counter-flows of ideal fluids. The ideal fluids are thermal sources of TE module flow in the opposite direction at the same flow rate and generate temperature differences on the hot and cold surfaces due to their different temperatures at the channel inlet. TE performance caused by different inlet temperatures of thermal fluids are numerically analyzed by using the finite-volume method on 3-D meshed physical models and then compared with those using a constant boundary temperature. The results show that voltage and current of the TE module increase gradually from a beginning moment to a steady flow and reach a stable value. The stable values increase with inlet temperature of the hot fluid when the inlet temperature of cold fluid is fixed. However, the time to get to the stable values is almost consistent for all the temperature differences. Moreover, the trend of TE performance using a fluid flow boundary is similar to that of using a constant boundary temperature. Furthermore, 3-D contours of fluid pressure, temperature, enthalpy, electromotive force, current density and heat flux are exhibited in order to clarify the influence of counter-flows of ideal fluids on TE generation. The current density and heat flux homogeneously distribute on an entire TE module, thus indicating that the counter-flows of thermal fluids have high potential to bring about fine performance for TE modules.

High Tc Superconducting Magnet Excited by a Semiconductor Thermoelectric Element

NASA Astrophysics Data System (ADS)

Kuriyama, T.; Ono, M.; Tabe, S.; Oguchi, A.; Okamura, T.

2006-04-01

A high Tc superconducting (HTS) magnet excited by a thermal electromotive force of a thermoelectric element is studied. This HTS magnet has the advantages of compactness, lightweight and continuous excitation in comparison with conventional HTS magnets, because this HTS magnet does not need a large external power source. In this system, a heat input into the cryogenic environment is necessary to excite the thermoelectric element for constant operation. This heat generation, however, causes a rise in temperature of an HTS coil and reduces the system performance. In this paper, a newly designed magnet system which adopted a two-stage GM cryocooler was investigated. It enabled us to control the temperature of a thermoelectric element and that of an HTS coil independently. The temperature of the HTS coil could be kept at 10-20 K at the second stage of the GM cryocooler, while the thermoelectric element could be excited at higher temperature in the range of 50-70 K at the first stage, where the performance of the thermoelectric element was higher. The experimental results on this HTS magnet are shown and the possibility of the thermoelectric element as a main power source of the HTS magnets is discussed.

Vulnerability of US thermoelectric power generation to climate change when incorporating state-level environmental regulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Lu; Hejazi, Mohamad; Li, Hongyi

This study explores the interactions between climate and thermoelectric generation in the U.S. by coupling an Earth System Model with a thermoelectric power generation model. We validated model simulations of power production for selected power plants (~44% of existing thermoelectric capacity) against reported values. In addition, we projected future usable capacity for existing power plants under two different climate change scenarios. Results indicate that climate change alone may reduce average thermoelectric generating capacity by 2%-3% by the 2060s. Reductions up to 12% are expected if environmental requirements are enforced without waivers for thermal variation. This study concludes that the impactmore » of climate change on the U.S. thermoelectric power system is less than previous estimates due to an inclusion of a spatially-disaggregated representation of environmental regulations and provisional variances that temporarily relieve power plants from permit requirements. This work highlights the significance of accounting for legal constructs in which the operation of power plants are managed, and underscores the effects of provisional variances in addition to environmental requirements.« less

Pumped Fluid Loop Heat Rejection and Recovery Systems for Thermal Control of the Mars Science Laboratory

NASA Technical Reports Server (NTRS)

Bhandari, Pradeep; Birur, Gajanana; Prina, Mauro; Ramirez, Brenda; Paris, Anthony; Novak, Keith; Pauken, Michael

2006-01-01

This viewgraph presentation reviews the heat rejection and heat recovery system for thermal control of the Mars Science Laboratory (MSL). The MSL mission will use mechanically pumped fluid loop based architecture for thermal control of the spacecraft and rover. The architecture is designed to harness waste heat from an Multi Mission Radioisotope Thermo-electric Generator (MMRTG) during Mars surface operations for thermal control during cold conditions and also reject heat during the cruise aspect of the mission. There are several test that are being conducted that will insure the safety of this concept. This architecture can be used during any future interplanetary missions utilizing radioisotope power systems for power generation.

Terbium Ion Doping in Ca3Co4O9: A Step towards High-Performance Thermoelectric Materials

PubMed Central

Saini, Shrikant; Yaddanapudi, Haritha Sree; Tian, Kun; Yin, Yinong; Magginetti, David; Tiwari, Ashutosh

2017-01-01

The potential of thermoelectric materials to generate electricity from the waste heat can play a key role in achieving a global sustainable energy future. In order to proceed in this direction, it is essential to have thermoelectric materials that are environmentally friendly and exhibit high figure of merit, ZT. Oxide thermoelectric materials are considered ideal for such applications. High thermoelectric performance has been reported in single crystals of Ca3Co4O9. However, for large scale applications single crystals are not suitable and it is essential to develop high-performance polycrystalline thermoelectric materials. In polycrystalline form, Ca3Co4O9 is known to exhibit much weaker thermoelectric response than in single crystal form. Here, we report the observation of enhanced thermoelectric response in polycrystalline Ca3Co4O9 on doping Tb ions in the material. Polycrystalline Ca3−xTbxCo4O9 (x = 0.0–0.7) samples were prepared by a solid-state reaction technique. Samples were thoroughly characterized using several state of the art techniques including XRD, TEM, SEM and XPS. Temperature dependent Seebeck coefficient, electrical resistivity and thermal conductivity measurements were performed. A record ZT of 0.74 at 800 K was observed for Tb doped Ca3Co4O9 which is the highest value observed till date in any polycrystalline sample of this system. PMID:28317853

Metallization for Yb14MnSb11-Based Thermoelectric Materials

NASA Technical Reports Server (NTRS)

Firdosy, Samad; Li, Billy Chun-Yip; Ravi, Vilupanur; Sakamoto, Jeffrey; Caillat, Thierry; Ewell, Richard C.; Brandon, Erik J.

2011-01-01

Thermoelectric materials provide a means for converting heat into electrical power using a fully solid-state device. Power-generating devices (which include individual couples as well as multicouple modules) require the use of ntype and p-type thermoelectric materials, typically comprising highly doped narrow band-gap semiconductors which are connected to a heat collector and electrodes. To achieve greater device efficiency and greater specific power will require using new thermoelectric materials, in more complex combinations. One such material is the p-type compound semiconductor Yb14MnSb11 (YMS), which has been demonstrated to have one of the highest ZT values at 1,000 C, the desired operational temperature of many space-based radioisotope thermoelectric generators (RTGs). Despite the favorable attributes of the bulk YMS material, it must ultimately be incorporated into a power-generating device using a suitable joining technology. Typically, processes such as diffusion bonding and/or brazing are used to join thermoelectric materials to the heat collector and electrodes, with the goal of providing a stable, ohmic contact with high thermal conductivity at the required operating temperature. Since YMS is an inorganic compound featuring chemical bonds with a mixture of covalent and ionic character, simple metallurgical diffusion bonding is difficult to implement. Furthermore, the Sb within YMS readily reacts with most metals to form antimonide compounds with a wide range of stoichiometries. Although choosing metals that react to form high-melting-point antimonides could be employed to form a stable reaction bond, it is difficult to limit the reactivity of Sb in YMS such that the electrode is not completely consumed at an operating temperature of 1,000 C. Previous attempts to form suitable metallization layers resulted in poor bonding, complete consumption of the metallization layer or fracture within the YMS thermoelement (or leg).

Recent progress in half-Heusler thermoelectric materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Lihong; Zhang, Qinyong; Yuan, Bo

2016-04-15

Highlights: • Summarize the recent progress and advances in HH thermoelectric materials. • Preparing nanocomposites could reduce thermal conductivity. • Introducing enhance phonon scattering could further reduce the thermal conductivity. • Forming ternary systems to reducing the cost effectively. • The new class of HHs presents another opportunity to further optimize the HH system. - Abstract: Half-Heusler (HH) thermoelectric (TE) materials have been attracting extensive research interest over the last two decades, owing to their thermal stability, mechanical strength, and moderate ZT. This material system are potential candidates for medium to high temperature applications, which is close to the temperaturemore » range of most industrial waste heat sources. In this mini-review article, we briefly summarize the recent progress and advances in HH thermoelectric materials. Some effectively available approaches, such as HH nanocomposites to reduce thermal conductivity, using larger atomic mass and size differences to enhance phonon scattering to further reduce the thermal conductivity, forming ternary systems following the cost effective approach. In addition, new thermoelectric HH members are also discussed in this article, which points out that many new HH compounds may be possible for TE applications.« less

Using high thermal stability flexible thin film thermoelectric generator at moderate temperature

NASA Astrophysics Data System (ADS)

Zheng, Zhuang-Hao; Luo, Jing-Ting; Chen, Tian-Bao; Zhang, Xiang-Hua; Liang, Guang-Xing; Fan, Ping

2018-04-01

Flexible thin film thermoelectric devices are extensively used in the microscale industry for powering wearable electronics. In this study, comprehensive optimization was conducted in materials and connection design for fabricating a high thermal stability flexible thin film thermoelectric generator. First, the thin films in the generator, including the electrodes, were prepared by magnetron sputtering deposition. The "NiCu-Cu-NiCu" multilayer electrode structure was applied to ensure the thermal stability of the device used at moderate temperature in an air atmosphere. A design with metal layer bonding and series accordant connection was then employed. The maximum efficiency of a single PN thermocouple generator is >11%, and the output power loss of the generator is <10% after integration.

A Thermoelectric Energy Harvesting System for Powering Wireless Sensors in Nuclear Power Plants

NASA Astrophysics Data System (ADS)

Chen, Jie; Klein, Jackson; Wu, Yongjia; Xing, Shaoxu; Flammang, Robert; Heibel, Michael; Zuo, Lei

2016-10-01

Safety is the most important issue in the development of nuclear energy. This paper reports experimental studies of a thermoelectric energy harvesting system designed for integration in a nuclear power plant capable of performing in radiation rich environments and producing enough power to run wireless sensors meant to increase plant safety. Furthermore, the system, which utilizes wasted heat present in coolant system piping, has the unique ability to provide power in both normal and accidental situations, to run the sensors without the need for external power. Two energy harvesting prototypes were designed utilizing a heat pipe for heat transfer. The first can supply a maximum power of 2.25 W using two Bi2Te3 thermoelectric modules of 2.79cm (1.1") × 2.79 cm (1.1”), in a source temperature near 250 °C. A second design was put forward to extend the application in higher-temperature primary loops, in which one PbTe-Bi2Te3 hybrid TEG module of 5.6cm (2.2") × 5.6 cm (2.2") can provide a power of 3.0 W when the hot side temperature reaches 340 °C. In addition to the energy harvester, wireless communication circuits were developed along with an integrated power management circuit for wireless data transmission. A high intensity gamma radiation experiment was conducted during which each component was irradiated. A total dose of 200 kGy±10% (20M rads) was applied to the first prototype in order to approximate the expected lifetime accumulation for one implemented thermoelectric generator. Results showed that thermoelectric modules used in the prototype had no reduction in voltage output throughout irradiation. Throughout the experiment the harvester system witnessed a small voltage drop in open circuit voltage attributed to a reduction in heat pipe performance from radiation exposure. We also acquired a baseline radiation survivability level for non-hardened, non-shielded electronics of 102 Gy.

The Effects of Doping and Processing on the Thermoelectric Properties of Platinum Diantimonide Based Materials for Cryogenic Peltier Cooling Applications

NASA Astrophysics Data System (ADS)

Waldrop, Spencer Laine

The study of thermoelectrics is nearly two centuries old. In that time a large number of applications have been discovered for these materials which are capable of transforming thermal energy into electricity or using electrical work to create a thermal gradient. Current use of thermoelectric materials is in very niche applications with contemporary focus being upon their capability to recover waste heat. A relatively undeveloped region for thermoelectric application is focused upon Peltier cooling at low temperatures. Materials based on bismuth telluride semiconductors have been the gold standard for close to room temperature applications for over sixty years. For applications below room temperature, semiconductors based on bismuth antimony reign supreme with few other possible materials. The cause of this diculty in developing new, higher performing materials is due to the interplay of the thermoelectric properties of these materials. The Seebeck coecient, which characterizes the phenomenon of the conversion of heat to electricity, the electrical conductivity, and the thermal conductivity are all interconnected properties of a material which must be optimized to generate a high performance thermoelectric material. While for above room temperature applications many advancements have been made in the creation of highly ecient thermoelectric materials, the below room temperature regime has been stymied by ill-suited properties, low operating temperatures, and a lack of research. The focus of this work has been to investigate and optimize the thermoelectric properties of platinum diantimonide, PtSb2, a nearly zero gap semiconductor. The electronic properties of PtSb2 are very favorable for cryogenic Peltier applications, as it exhibits good conductivity and large Seebeck coecient below 200 K. It is shown that both n- and p-type doping may be applied to this compound to further improve its electronic properties. Through both solid solution formation and processing

Performance Analysis of Thermoelectric Modules Consisting of Square Truncated Pyramid Elements Under Constant Heat Flux

NASA Astrophysics Data System (ADS)

Oki, Sae; Natsui, Shungo; Suzuki, Ryosuke O.

2018-01-01

System design of a thermoelectric (TE) power generation module is pursued in order to improve the TE performance. Square truncated pyramid shaped P-N pairs of TE elements are connected electronically in series in the open space between two flat insulator boards. The performance of the TE module consisting of 2-paired elements is numerically simulated using commercial software and original TE programs. Assuming that the heat radiating into the hot surface is regulated, i.e., the amount of heat from the hot surface to the cold one is steadily constant, as it happens for solar radiation heating, the performance is significantly improved by changing the shape and the alignment pattern of the elements. When the angle θ between the edge and the base is smaller than 72°, and when the cold surface is kept at a constant temperature, two patterns in particular, amongst the 17 studied, show the largest TE power and efficiency. In comparison to other geometries, the smarter square truncated pyramid shape can provide higher performance using a large cold bath and constant heat transfer by heat radiation.

Performance Analysis of Thermoelectric Modules Consisting of Square Truncated Pyramid Elements Under Constant Heat Flux

NASA Astrophysics Data System (ADS)

Oki, Sae; Natsui, Shungo; Suzuki, Ryosuke O.

2018-06-01

System design of a thermoelectric (TE) power generation module is pursued in order to improve the TE performance. Square truncated pyramid shaped P-N pairs of TE elements are connected electronically in series in the open space between two flat insulator boards. The performance of the TE module consisting of 2-paired elements is numerically simulated using commercial software and original TE programs. Assuming that the heat radiating into the hot surface is regulated, i.e., the amount of heat from the hot surface to the cold one is steadily constant, as it happens for solar radiation heating, the performance is significantly improved by changing the shape and the alignment pattern of the elements. When the angle θ between the edge and the base is smaller than 72°, and when the cold surface is kept at a constant temperature, two patterns in particular, amongst the 17 studied, show the largest TE power and efficiency. In comparison to other geometries, the smarter square truncated pyramid shape can provide higher performance using a large cold bath and constant heat transfer by heat radiation.

Anisotropic thermoelectric properties of layered compounds in SnX2 (X = S, Se): a promising thermoelectric material.

PubMed

Sun, Bao-Zhen; Ma, Zuju; He, Chao; Wu, Kechen

2015-11-28

Thermoelectrics interconvert heat to electricity and are of great interest in waste heat recovery, solid-state cooling and so on. Here we assessed the potential of SnS2 and SnSe2 as thermoelectric materials at the temperature gradient from 300 to 800 K. Reflecting the crystal structure, the transport coefficients are highly anisotropic between a and c directions, in particular for the electrical conductivity. The preferred direction for both materials is the a direction in TE application. Most strikingly, when 800 K is reached, SnS2 can show a peak power factor (PF) of 15.50 μW cm(-1) K(-2) along the a direction, while a relatively low value (11.72 μW cm(-1) K(-2)) is obtained in the same direction of SnSe2. These values are comparable to those observed in thermoelectrics such as SnSe and SnS. At 300 K, the minimum lattice thermal conductivity (κmin) along the a direction is estimated to be about 0.67 and 0.55 W m(-1) K(-1) for SnS2 and SnSe2, respectively, even lower than the measured lattice thermal conductivity of Bi2Te3 (1.28 W m(-1) K(-1) at 300 K). The reasonable PF and κmin suggest that both SnS2 and SnSe2 are potential thermoelectric materials. Indeed, the estimated peak ZT can approach 0.88 for SnSe2 and a higher value of 0.96 for SnS2 along the a direction at a carrier concentration of 1.94 × 10(19) (SnSe2) vs. 2.87 × 10(19) cm(-3) (SnS2). The best ZT values in SnX2 (X = S, Se) are comparable to that in Bi2Te3 (0.8), a typical thermoelectric material. We hope that this theoretical investigation will provide useful information for further experimental and theoretical studies on optimizing the thermoelectric properties of SnX2 materials.

NASA 50 amp hour nickel cadmium battery waste heat determination

NASA Technical Reports Server (NTRS)

Mueller, V. C.

1980-01-01

A process for determining the waste heat generated in a 50-ampere-hour, nickel cadmium battery as a function of the discharge rate is described and results are discussed. The technique involved is essentially calibration of the battery as a heat transfer rate calorimeter. The tests are run at three different levels of battery activity, one at 40-watts of waste heat generated, one at 60, and one at 100. Battery inefficiency ranges from 14 to 18 percent at discharge rates of 284 to 588 watts, respectively and top-of-cell temperatures of 20 C.

Thermoelectric Properties of Highly Conductive Poly(3,4-ethylenedioxythiophene) Polystyrene Sulfonate Printed Thin Films.

PubMed

Beretta, Davide; Barker, Alex J; Maqueira-Albo, Isis; Calloni, Alberto; Bussetti, Gianlorenzo; Dell'Erba, Giorgio; Luzio, Alessandro; Duò, Lamberto; Petrozza, Annamaria; Lanzani, Guglielmo; Caironi, Mario

2017-05-31

Organic conductors are being evaluated for potential use in waste heat recovery through lightweight and flexible thermoelectric generators manufactured using cost-effective printing processes. Assessment of the potentiality of organic materials in real devices still requires a deeper understanding of the physics behind their thermoelectric properties, which can pave the way toward further development of the field. This article reports a detailed thermoelectric study of a set of highly conducting inkjet-printed films of commercially available poly(3,4-ethylenedioxythiophene) polystyrene sulfonate formulations characterized by in-plane electrical conductivity, spanning the interval 10-500 S/cm. The power factor is maximized for the formulation showing an intermediate electrical conductivity. The Seebeck coefficient is studied in the framework of Mott's relation, assuming a (semi-)classical definition of the transport function. Ultraviolet photoelectron spectroscopy at the Fermi level clearly indicates that the shape of the density of states alone is not sufficient to explain the observed Seebeck coefficient, suggesting that carrier mobility is important in determining both the electrical conductivity and thermopower. Finally, the cross-plane thermal conductivity is reliably extracted thanks to a scaling approach that can be easily performed using typical pump-probe spectroscopy.

Compatibility of segmented thermoelectric generators

NASA Technical Reports Server (NTRS)

Snyder, J.; Ursell, T.

2002-01-01

It is well known that power generation efficiency improves when materials with appropriate properties are combined either in a cascaded or segmented fashion across a temperature gradient. Past methods for determining materials used in segmentation weremainly concerned with materials that have the highest figure of merit in the temperature range. However, the example of SiGe segmented with Bi2Te3 and/or various skutterudites shows a marked decline in device efficiency even though SiGe has the highest figure of merit in the temperature range. The origin of the incompatibility of SiGe with other thermoelectric materials leads to a general definition of compatibility and intrinsic efficiency. The compatibility factor derived as = (Jl+zr - 1) a is a function of only intrinsic material properties and temperature, which is represented by a ratio of current to conduction heat. For maximum efficiency the compatibility factor should not change with temperature both within a single material, and in the segmented leg as a whole. This leads to a measure of compatibility not only between segments, but also within a segment. General temperature trends show that materials are more self compatible at higher temperatures, and segmentation is more difficult across a larger -T. The compatibility factor can be used as a quantitative guide for deciding whether a material is better suited for segmentation orcascading. Analysis of compatibility factors and intrinsic efficiency for optimal segmentation are discussed, with intent to predict optimal material properties, temperature interfaces, and/or currentheat ratios.

Ultralow thermal conductivity and high thermoelectric figure of merit in SnSe crystals.

PubMed

Zhao, Li-Dong; Lo, Shih-Han; Zhang, Yongsheng; Sun, Hui; Tan, Gangjian; Uher, Ctirad; Wolverton, C; Dravid, Vinayak P; Kanatzidis, Mercouri G

2014-04-17

The thermoelectric effect enables direct and reversible conversion between thermal and electrical energy, and provides a viable route for power generation from waste heat. The efficiency of thermoelectric materials is dictated by the dimensionless figure of merit, ZT (where Z is the figure of merit and T is absolute temperature), which governs the Carnot efficiency for heat conversion. Enhancements above the generally high threshold value of 2.5 have important implications for commercial deployment, especially for compounds free of Pb and Te. Here we report an unprecedented ZT of 2.6 ± 0.3 at 923 K, realized in SnSe single crystals measured along the b axis of the room-temperature orthorhombic unit cell. This material also shows a high ZT of 2.3 ± 0.3 along the c axis but a significantly reduced ZT of 0.8 ± 0.2 along the a axis. We attribute the remarkably high ZT along the b axis to the intrinsically ultralow lattice thermal conductivity in SnSe. The layered structure of SnSe derives from a distorted rock-salt structure, and features anomalously high Grüneisen parameters, which reflect the anharmonic and anisotropic bonding. We attribute the exceptionally low lattice thermal conductivity (0.23 ± 0.03 W m(-1) K(-1) at 973 K) in SnSe to the anharmonicity. These findings highlight alternative strategies to nanostructuring for achieving high thermoelectric performance.