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The Department of Thermoelectric Functional Materials at
the DLR Institute of Materials Research is collaborating with part-
ners from the automotive manufacturing and supplier industries
to make thermoelectric generators available for standard use in
vehicles. Their aim is to create highly efficient thermoelectric
materials and generators for use at temperatures of up to 400
degrees Celsius. In Project TEG, funded by the German Federal
Ministry of Economics and Technology, DLR and its cooperating
partners, BMW and EMITEC Gesellschaft für Emissionstechnol-
ogie mbH, have managed to develop a cylindrical TEG for
integration into the exhaust gas heat exchangers of diesel
engines. At the 2012 International Thermoelectric Conference,
DLR’s poster contribution on this topic was awarded best applica-
tion from among 300 or so presentations.
The DLR researchers used lead telluride for the first
prototypes and demonstration models. This is a high-temper-
ature material with the best availability and technological
maturity to date. However, lead-free functional materials
must be found for this technology to be used widely. For this
reason, ongoing research work is increasingly focusing on
TEG module technology based on materials from the class of
skutterudites. The electrical and mechanical properties of
these functional materials are being researched and
Automobile manufacturers around the world are working on fuel-efficient vehicles. There are a number of ways
of achieving this – increased electrification of motor vehicles, fuel-efficient engines and use of waste heat from
combustion engines. Using thermoelectric generators (TEGs), heat that would otherwise be lost in the exhaust
system can be converted into electrical energy, creating a significantly improved energy balance for modern vehicles.
DLR is investigating.
Functional materials for vehicle thermoelectric technology
improve the energy balance
By Reinhard Sottong
Powerful powder
Thermoelectric generator module
used to convert excess heat into
electrical power
optimised at DLR. The researchers are aiming to increase the
material efficiency and make the modules suitable for long-
term use. They are directing their attention specifically
towards raw materials that can be produced with adequate
throughput and fed into the development and manufacturing
stages. This is something that has so far proven to be a prac-
tical hindrance for the industrial application of thermoelectric
systems. Manufacturing the materials in glass vials is certainly
a suitable method for laboratory research, but is too compli-
cated and expensive for mass production.
Using this technique, thermoelectric materials can only be
synthesised in quantities of significantly less than 100 grams per
batch. It is for this reason that the scientists at the Institute of
Materials Research are investigating other manufacturing routes
that will allow for greater material throughput. They see one
possible technique in atomising the molten thermoelectric material,
a process that is already used for many materials at industrial scales.
Now that lead telluride has been synthesised, doped and atomised
to produce powder in the test facility, the current challenge facing
the DLR team is to be able to carry out the atomisation of skutteru-
dite materials with the required quality. In subsequent stages, this
process will be optimised in terms of the quality of the materials to
provide the basis for industrial manufacturing of large quantities of
thermoelectric powder. Preparations are now underway, with the
support of DLR Technology Marketing, to transfer this technology.
In-depth discussions are being held with a European industrial
partner on scaling up the technology for a pilot production line.
The progress being made suggests that DLR researchers will be able
to make a significant contribution to the establishment of thermoe-
lectric systems. This would make vehicles more efficient by
exploiting their excess heat.
•
About the author:
Reinhard Sottong works in the Department of Thermoelectric
Functional Materials at the DLR Institute of Materials Research in
Cologne. Thermoelectric generators for motor vehicles are the
subject of the physicist’s dissertation.
Equipment for atomisation of materials, with which DLR researchers
are developing the processes for manufacturing thermoelectric
powders.
More information:
materials research
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