RIST Outline

Division of Thermoelectrics for Waste Heat Recovery

Director  Tsutomu Iida:Professor, Department of Materiatl Science and Technology, Faculty of Industrial Science and Technology 
Research Content R&D on waste heat recovery systems using solid-state thermoelectric energy conversion technique
Objetcitves To research and develop materials and power generation systems which is used for the waste heat recovery for the automotive and industrial application fields.

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-The Research Highlight, 2016-

The earth’s environment will undergo great changes within our own lifetime if we keep consuming fossil energy on such a massive scale as we are doing now. The earth’s environment could drastically change in our children’s era due to global warming.“ What about the generation of atomic power?” We worry that we are dumping atomic waste caused by our wastefulness on to our children or our grandchildren, or even that we are passing the problem on to their descendents some thousands of years in the future. Although an individual person possesses only limited power, we feel that the time has arrived when we must start moving towards a“ sustainable society for the future.”

Human beings are really just creatures who are supported by the ecological food chain, although we supposedly possess higher intelligence compared with the other creatures that inhabit the earth. Thus, we must start to think more seriously about the global environment….

Improvements in energy and environmental problems cannot progress at a sufficiently high pace to make a difference sometime today or tomorrow. Therefore, proactive studies that look ahead for some tens of years are necessary. From a material’s standpoint, not only steps to ensure future resources, but also studies of materials that could maximize energy conversion efficiency are required. From the view point of environmental conservation, studies of materials that represent a low environmental burden are needed. There is now a trend towards the prohibition of some poisonous materials that were previously permitted to be used in small amounts, irrespective of how desirable their performance is.

In this Division, we have been developing materials for energy conversion to tackle the global warming that is being caused by the mass consumption of fossil fuels. In particular, considerable weight is currently being placed on the study of materials for power generation from waste heat. Using these materials, heat energy, which is the final phase of energy consumption, can be recycled into electrical energy. Concurrently, we have also been pursuing environmentally friendly semiconductor energy conversion materials, while studying environmentally“ low-load” production processes. Environmental semiconductors are semiconductor materials that are abundant on the earth and which comprise of materials that are friendly to living creatures and to the environment.

The main advantage of thermoelectric conversion as compared to thermodynamic conversion results from the absence of any moving parts. Being entirely static, the device is vibrationless and is not affected by wear. In the context of increasing energy prices and climate change, thermo-electric conversion is of the highest interest for producing electric power from waste heat. It has also attractive applications for low and near ambient temperature refrigeration.

Especially, the automotive industry is anxious for the installation of thermoelectric generators (TEG) because of the strict fuel consumption regulation in EU. As is shown in the figure, almost all current models could not pass the regulation at 2020, except for some hybrid system or next generation of diesel engines. Since .70 % of initial gasoline is emitted as waste heat when we drive, if some percentages of discarded heat can be reused, then fuel consumption is improved. An on-board TEG system is one possible technique to conserve fuels and supply electricity. In our research division, we are currently working corresponding research issues listed below to proceed appropriate thermoelectric materials and TEG adopted for the automotive application and the industrial furnaces.

Thermoelectric material development and fabrication
  • Synthesis of powders and bulk materials using methods of

- High energy ball milling (synthesis/mechanical alloy/doping)
- Combined process of vibration ball milling and spark plasma sintering (synthesis & doping)
- All molten synthesis (synthesis & doping)
- Manufacture-oriented all molten synthesis
- Mechanochemical and self-flux synthesis

  • Fabrication of nano-structures with enhanced functionality as post process of the materials developed with fabrication methods of

- High energy ball milling (nanostructurization)
- Melt spin synthesis (nanostructurization)
- Direct nanostructure-formation during spark plasma sintering process

  • Powder compaction and sintering for thermoelectric chip fabrication

- Standard Material Consolidation (thermoelectric chip fabrication)
- Spark plasma sintering (thermoelectric chip fabrication)
- Plasma activated sintering (thermoelectric chip fabrication)

Application and development of advanced characterization and measurement methods for thermoelectrics

- Physical properties of thermoelectrics
- Structure of thermoelectrics from meso- to atomic scale
- Combined approach of XRD, SEM and TEM
- Chemistry and structure at the nanoscale by advanced electron microscopy
- Electronic band structural analysis using synchrotron based techniques
- In-situ analyses for durability enhancement

Computational thermoelectric material and power generation module structure design

Modeling and rational design of thermoelectric material.
- Identifying fundamental properties, including temperature dependence of
thermoelectric power, and optimal uses of the material classes delivered by the first
principles calculations using the all electron FLAPW/LDA (Code:ABCAP)
- Designing the optimal nanostructures from lattice thermal conductivity perspective
using the mulitscale phonon transport calculations based on first principles.
- Finite elemental

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Future Development Goals

To research and develop appropriate thermoelectric materials and thermoelectric power generation systems which is installed to the automotive exhaust line and the industrial furnaces, in order to obtain fuel-efficient system.

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In this Division, we have been developing thermoelectric materials and systems for energy conversion to tackle
the global warming that is being caused by the mass consumption of fossil fuels. Using our state-of-the-art thermoelectric technology, heat energy, which is the final phase of energy consumption, can be recycled into electrical energy. Concurrently, we have also been pursuing environmentally friendly semiconductor energy conversion materials, while studying environmentally “low-load” production processes.

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