Thermoelectric power generation with converted waste heat: What are the advantages for next generation electric vehicles? What materials offer a high conversion efficiency? As a peek into the themes of our upcoming event on Thermal management for EV/HEVs we prepared this exclusive presentation by Dr. Sascha Populoh, Materials and Energy Conversion at Empa for you to download for free: http://bit.ly/Presentation-Populoh

1. Dear Expert,
The 5th Thermal Management for EV/HEV Conference 2016 aims to explore
practical solutions for optimal cooling and heating as an integrated part of vehicle
development.
Our conference will bring together experts from along the value chain to ensure
maximum knowledge transfer, professional exchange and networking
opportunities. For more information and the schedule of events, please download
the agenda, email at eq@iqpc.de or call +49 (0) 30 20 913 - 274
We look forward to meeting you in February 2016 in Berlin!
Today we are pleased to share with you a presentation by one of our speakers from
our previous Conference.

2. Dr. Sascha Populoh, materials and Energy Conversion at Empa - Swiss Federal
Laboratories for Materials Science and Technology:
Kind regards,
Automotive IQ / A Division of

3. Waste heat recovery by
thermoelectricity
Sascha Populoh
Thermal Management for EV/HEV
Empa, Swiss Federal Laboratories for Materials Research and Technology

4. Outline
• Introduction to thermoelectricity
• Materials and module development based on
Half Heusler compounds

5. The thermopower:
classical definition of S

6. Thermoelectric modules
load Ra
p p p pn n n n
cold
hotElectr.
current
n p n p
RL
e- +
e-
e- e-
e-
e-e- e-
e-e-
e- e-+ +
e- e-+ +
V = S ΔT

7. Thermoelectric power generation

8. Advantages of thermoelectric
power generation
o heat engine without moving parts
o no mechanical or chemical processes involved
 silent, emission free, no vibrations
 robust and durable, nearly no
maintenance, high reliability (> 250’000 h)
o flexible: power from W to MW and from
T < 1 K to T > 1000 K
A thermoelectric generator is a unique heat engine in which
“mobile charge carriers serve as working fluid”.
T≈37°C
skin
T>1000°C
solar
Voyager 1 & 2
start 1977
3 RTGs à 158 W

9. Automotive applications
P. Soltic et al., Empa
About
83% (inefficient old gasoline passenger car) to
55% (heavy duty diesel truck)
of the fuel energy is converted
into heat

10. Outline
• Introduction to thermoelectricity
• Materials and module development based on
Half Heusler compounds

11. Materials development:
n‐type Half Heusler (XYZ)
High ǀSǀ (300 µV/K)
Low ρ (10‐4 Ωm)
High κ (10 W/Km)
Populoh et al. Scripta Mater (2012), 66 (12), 1073.
Isoelectronic substitution on the
X‐position: Ti0.37Zr0.37Hf0.26NiSn

12. HH p‐type: Ti(CoFe)Sb with
InSb nanoinclusions
InSb
Boundary Scattering
Electron Filtering Effect
 ↓
 ↑ without decreasing 
Electron injection Effect  ↑
1.0 at.% InSb NI: ~ 450% increase of ZT
Xie et al. Acta Mater (2013), 61 (6), 2087.

13. Assembly of HH‐module

14. Characterisation
300 400 500 600 700 800 900
0.0
0.1
0.2
0.3
0.4
0.5
0.6
4
5
6
7
2E-5
4E-5
6E-5
8E-5
1E-4
ZT
Temperature (K)
(c)
Th.conductivity(W/Km)
El.resistivity(m)
-300
-270
-240
-210
-180
-150
(b)
Seebeckcoefficient(V/K)
(a)
Populoh et al. Materials (2013), 6 (4), 1326.

15. Comparison with other
modules
Module Material T (K)
Max power output
(mW)
Leg dimensions
(mm)
Power densitity
(mW/cm3)
HH‐Empa TiZrHfNiSn 565 44 4 times 2*2*4 700
Heusler
Mikamichi Fe2VAl 300 940 36 times 5*5*5 280
Oxide Empa CaMnO3 622 88 4 times 4*4*5 275
Oxide Funahashi Ca3Co4O9 500 94 4 times 3.7*4.5*4.7 660
Assembly of a module comprising high ZT materials is
underway

16. Summary
• Thermoelectricity is a highly reliable possibility
to convert waste heat to electricity
• Max. Power T‐Hex: @ Tcold40°C= 120 W,
@Tcold80°C= 78 W
• Thermoelectric HH compounds with a high
conversion efficiency
• First unileg Test module based HH compounds

17. Outlook
• Redesign of 2nd generation T‐Hex
for higher energy extraction,
and later catalytic covering of fins
• Materials research: Combination of
substitution and nano‐inclusion approach for
new high ZT compounds
• Module development: use of materials with
ZT ≈ 1, contact material investigation

18. That’s all folks!
Thanks for your attention

19. Supplementary

20. TEG TEP1‐1265‐0.8
*nmat 2090 / Complex thermoelectric materials / G. Jeffrey Snyder* and Eric S. Toberer
Materials Science, California Institute of Technology, 1200 East California Boulevard, Pasadena, California 91125, USA
Spezification of the Module TEP1‐1265‐0.8
Hot side temperatur (°C) 330
Cold side temperatur (°C) 30
Open circuit voltage (V) 9.9
Matched load resistance (ohms) 1.67
Matched load output current (A) 2.9
Matched load output power (W) 14.5
Heat flow across the module (W) ~ 302
Heat flow density (W cm‐2) ~ 9.6
AC resistance (ohms) measured
under 27 °C at 1000 Hz
0.7 ~ 1.0
Temperature field from 80‐350°C
* * *
N / P type of Module BiTe based material

21. …Join the 5th International Conference Thermal Management for
EV/HEV in Germany, February 16-18.
This forum will bring speakers from the automotive industry as
well as top Battery experts from around the world:
 Explore practical solutions for optimal cooling and heating thermal systems for EV
and HEVs
 Advance powertrain architecture for optimum thermal distribution
 Identify hardware hazards and eliminate risks from systems concept phase
 Manage thermal management as an integrated part of vehicle development
 Find solutions for optimized passenger comfort and energy efficiency of cabin
climate control systems