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Thermoelectrics

[Due to the increasing size of the archives, each topic page now contains only the prior 365 days of content. Access to older stories is now solely through the Monthly Archive pages or the site search function.]

MIT team finds chemical functionalization can lead to efficient graphene-based thermoelectric materials

April 14, 2015

Researchers at MIT are predicting that predict that suitable chemical functionalization of graphene can result in a large enhancement in the Seebeck coefficient for thermoelectric materials, leading to an increase in the room-temperature power factor of a factor of 2 compared to pristine graphene, despite degraded electrical conductivity.

Furthermore, the presence of patterns on graphene reduces the thermal conductivity, which when taken together leads to an increase in the figure of merit for functionalized graphene by up to 2 orders of magnitude over that of pristine graphene, reaching its maximum ZT ∼ 3 at room temperature according to their calculations, as reported in a paper in the ACS journal Nano Letters. These results suggest that appropriate chemical functionalization could lead to efficient graphene-based thermoelectric materials.

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S. Korean/US team develops new production method for inexpensive and more efficient thermoelectric materials

April 03, 2015

Researchers in South Korea at IBS Center for Integrated Nanostructure Physics along with Samsung Advanced Institute of Technology, the Department of Nano Applied Engineering at Kangwon National University, the Department of Energy Science at Sungkyunkwan University, and Materials Science department at CalTech have developed a new method for creating a novel and much more efficient thermoelectric bismuth antimony telluride (Bi0.5Sb1.5Te3) alloy.

In tests reported in a paper in the journal Science, the efficiency (zT) reached 2.01 at 320 K (46.85 ˚C) within the range of 1.86 ±0.15 at 320 K for 30 samples, nearly doubling the industry standard. When the melt spun alloy is used in a Peltier cooler, the results are also significant. The new material was able achieve a temperature change of 81 K at 300 K (26.85° C).

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SUTD team proposes low-temperature thermionic converter with graphene cathode; about 45% efficiency

March 09, 2015

Researchers at the Singapore University of Technology and Design (SUTD) are proposing that it is possible to design an efficient graphene-cathode-based thermionic energy converter (TIC)—a device for converting heat to electricity leveraging the phenomenon of thermionic emission, or the release of electrons from a hot body—operating at around 900 K (626 °C) or lower, as compared with a conventional metal-based cathode TIC operating at about 1500 K (1227 °C).

With a graphene-based cathode at 900 K and a metallic anode, the efficiency of the proposed TIC would be about 45%, they concluded in a paper on the work published in the journal Physical Review Applied. If realized, an efficient, low-temperature TIC could provide a supplementary or an alternative approach to thermoelectric devices for waste heat recovery using low grade waste heat—i.e, from engine exhaust or industrial processes.

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GMZ Energy successfully demonstrates 1 kW thermoelectric generator for Bradley Fighting Vehicle

December 03, 2014

GMZ Energy, a market leader in the development of high-temperature thermoelectric generation (TEG) solutions, has successfully demonstrated a 1,000W TEG designed for diesel engine exhaust heat recapture in a Bradley Fighting Vehicle. (Earlier post.) This announcement follows GMZ’s June 2014 demonstration of its 200W diesel TEG. The company integrated five of its 200W TEGs into a single 1,000 W diesel engine solution that directly converts exhaust waste heat into electrical energy to increase fuel efficiency and lower costs.

With this demonstration, GMZ has successfully reached the next milestone in the $1.5 million vehicle efficiency program sponsored by the US Army Tank Automotive Research, Development and Engineering Center (TARDEC) and administered by the U.S. Department of Energy (DOE).

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Vanderbilt/ORNL team discovers new form of crystalline order that could be attractive for thermoelectric applications

November 17, 2014

A team of researchers from Vanderbilt University and Oak Ridge National Laboratory (ORNL) has discovered an entirely new form of crystalline order that simultaneously exhibits both crystal and polycrystalline properties, which they describe as “interlaced crystals.”

The interlaced crystal arrangement has properties that could make it ideal for thermoelectric applications. The discovery of materials with improved thermoelectric efficiency could increase the efficiency of electrical power generation, improve automobile mileage and reduce the cost of air conditioning. Writing in the journal Nature Communications, the researchers reported finding this unusual arrangement of atoms while studying nanoparticles made from the semiconductor copper-indium sulfide (CIS), which is being actively studied for use in solar cells.

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GMZ Energy develops new thermoelectric material with lower raw material costs, higher power output; Hafnium-free p-type half-Heusler

October 21, 2014

Researchers at GMZ Energy, a provider of nano-structured thermoelectric generation (TEG) power solutions for mobile and stationary waste-heat recovery (earlier post), with their colleagues at the University of Houston and Bosch, have developed a new Hafnium-free p-type half-Heusler material which offers substantially lower raw material cost than conventional half-Heusler materials. The material also features enhanced performance and mechanical strength due to GMZ’s patented nanostructuring process.

As presented in a paper published in the RSC journal Energy & Environmental Science, the new material improves thermoelectric power output compared to a conventional Hafnium-based product. Further, by replacing the costly Hafnium element with GMZ’s proprietary formulation, the overall cost-per-watt of the TEG is lowered. Cost reduction is beneficial for vehicle and industrial waste heat recovery applications, the developers noted in their paper.

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GMZ Energy announces new, high-power thermoelectric module: TG16-1.0

October 01, 2014

TG16small
TG16. Click to enlarge.

GMZ Energy, a developer of high temperature thermoelectric generation (TEG) solutions, has introduced the TG16-1.0, a new thermoelectric module capable of producing twice the power of the company’s first product, the TG8-1.0. By doubling the power density, GMZ’s new module substantially increases performance while maintaining a minimal footprint.

GMZ has been using TG8 modules in developing vehicular thermoelectric generators for the Bradley Fighting Vehicle (1 kW TEG) as well as to design and to integrate a light-duty vehicle TEG into a Honda Accord as part of a DOE-funded project. (Earlier post.)

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GMZ-led project tracking to deliver vehicular thermoelectric generators for Bradley Fighting Vehicle, Honda Accord

August 11, 2014

200Wteg
The assembled 200W TEG tested in June delivered 270W of output. Click to enlarge.

GMZ Energy and its partners are on track to deliver a 1 kW thermoelectric generator (TEG) for the Bradley Fighting Vehicle as well as to design and to integrate a light-duty vehicle TEG into a Honda Accord as part of a DOE-funded project. Thermoelectric materials convert temperature differences into electric voltage; a TEG in a vehicle is designed to convert waste heat to power. GMZ Energy, a provider of advanced nano-structured thermoelectric generation technology, was co-founded by MIT’s Professor Gang Chen and collaborator Zhifeng Ren of the University of Houston.

The project is using Half-Heusler (HH) thermoelectric materials (earlier post) in designing the vehicular TEG systems. Although these materials (ferromagnetic intermetallic alloys with a strong crystal structure that allows great stability at high temperatures) have a ZT (dimensionless figure of merit) lower than some other TE materials such as Skutterudites, the mechanical strength and the reliability of HH compensates for this deficit, according to GMZ.

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