Sponsored byUS Department of Energy

Energy Efficiency Renewable Energy (EERE) Waste Heat Recovery and Utilization Research and

Development for Passenger Vehicle and Light/Heavy Duty Truck

Applications

Jihui YangGM Research & Development Center

at 2009 DEER Conference, Dearborn, MIAugust 5, 2009

Outline Introduction Engineering Highlights Materials Research Highlights Future work and Summary

Develop Thermoelectric Technology for Automotive Waste Heat Recovery

Target : 10% fuel economy improvement without increasing emissions

Prove Commercial Viability

nm m mm m

log(Length scale)

Engineering

MaterialsScience

Chemistry

Physics

Competency

Electronic

Microstructural

0.001 0.0015 0.002 0.0025 0.003 0.0035 0.004 0.0045 0.0050

0.1

0.2

0.3

0.4

0.5

0.6

0.7

140612691131994.1856.8719.5582.2444.9307.6170.3

Lp [m]

W out

PbTe/TAGS85

Continuum

Atomistic

Objectives and Approach

•

Finalize TE generator and power electronics design•

Finalize vehicle thermal management and integration

•

TE module construction•

Improve material ZT and thermo-mechanical properties

Previous Year Accomplishments

Exhaust Heat - City Driving Cycle

0

10

20

30

40

50

60

70

80

0 500 1000 1500 2000 2500

Test Time (s)

kW

The Suburban was selected as a test vehicle because it simplified the modifications and installation of the prototype.

Fuel efficiency improvement will be better in small, fuel efficient vehicles than in large vehicles because the electrical load in small vehicles is a larger portion of the engine output.

TE Automotive Waste Heat Recovery Vehicle Selection –

Chevy Suburban

Case 08

TE ExhaustGenerator

Maximum module compression compliance

Quick disconnects for fluid flow

Quick disconnect exhaust connections

Pitched to drain condensate

Pitch designed for boil off

Sealed electronics

Located where current muffler is placed; new muffler will be located behind the axle perpendicular to vehicle axis Axially compliant for thermal expansion

mismatch

Interior View(module mounting)

TE ExhaustGenerator

Exhaust Generator GEN III Design

Power vs. Time - Urban drive cycle

0

200

400

600

800

1000

1200

0 500 1000 1500 2000 2500 3000

time [s]

Pow

er [W

]

Quasi-steady analysis - EES Transient analysis - ANSYS

Case 08

We expect ~ 1 mpg (~ 5 %) fuel economy improvement for Suburban (average 350 W and 600 W for the FTP city and highway driving cycles, respectively.)

This technology is well-suited to other vehicle platforms such as passenger cars and hybrids.

Subsystem Performance

GM TE Generator on a Chevy Suburban

GM TE Generator on a Chevy Suburban

Generator Animation

GM TE Generator Thermal Management

(a)

• Enclosure• Enclosure

• TE Modules• Guiding pins• TE Modules• Guiding pins

(b)

(c)

• Heat exchanger (copper)

• Cap plates• Studs• Mounting blocks• Cold heat sink• Vibration damping

mounts

• Heat exchanger (copper)

• Cap plates• Studs• Mounting blocks• Cold heat sink• Vibration damping

mounts

• The generator core is mounted to the enclosure through a series of isolation mounts to isolate harsh shock and vibration

• The enclosure will provide a sealed environment for the generator. • The enclosure will be stiff in the vertical axis of the generator, so as to provide rigidity

TE Generator Design

DC-DC

+

_TH TC

DC-DC

DC-DC

DC-DC

DC-DC

DC-DC

DC-DC

DC-DCTH TC

DC-DC

+

_TH TC

+

TH

_

TC

DC-DC

DC-DC

TH TC

a. b. c. d.

Q1 (IXYS 100N25P)

Cin

Lo

D1(IXYS DSSK 60-02AR) Co

From TE To Battery

VTE VBAT

VTEVBAT

VTE

+

-

FAN7371

VBHO

VS

VBATf

PWM(0 to 90%)

VDD

IN

GND

R1(NO)

-PowerCOMP1

RSHUNT

VBAT*Commanded MaxBattery Voltage

Sample&

Hold

+-

555Timer

OA1

OA2OA3

Current Mode Controller

COMP

PWMLogic

&DriversOA

VCC

VCC

VCC

VCC

VCC

VCC VCC

VCC

compensator

TVS

spillover circuit(battery voltage too high protect)

OA4

Open circuit voltagesampling timer

summer

voltagefollower

(gain = 1/2)

+-

+-

+-

+-

open cktvoltage

+-+

-

TVS

VCC

OA5

+-

VCC(= VBAT)

min input voltagecommand clamp = 2VBAT

-Power Comparator: TLC3702 (Dual)Comparators: LM311 or LM339 (Quad)OP Amps: TBD

TLC3702

shutdownpin

Aout

Bout

CS+CS-

UC2856Q

Four alternative TE power conversion architectures

Functional controlblock diagram

•

Completed a trade-off study to determine the electrical topology of the generator and the DC-to-DCconverter architecture

• Selected the design that maximizes reliability & efficiency over the driving cycles and minimizes system cost.

Power Electronics

Load resistance ()

0 20 40 60

Pow

er (W

)

0.0

0.5

1.0

1.5

2.0

(42.8, 10.5, 32.3) (86.4, 13.7, 72.7) (129.4, 17.0, 112.4) (171.9, 20.5, 151.4)(213.2, 23.8, 189.4)(253.6, 27.5, 226.1)

(TH, TC, T)

Load resistance ()

0 20 40 60

Effic

ienc

y (%

)

0

1

2

3

4

5

(42.8, 10.5, 32.3) (86.4, 13.7, 72.7) (129.4, 17.0, 112.4) (171.9, 20.5, 151.4)(213.2, 23.8, 189.4)(253.6, 27.5, 226.1)

(TH, TC, T)

13• Developed a novel solid-phase diffusion bonding process to fabricate

thermoelectric modules• Measured performance of some initial modules at various temperature gradients

Prototype Modules

4

δ

F illing  atomcage

δ

F illing  atomcage

S mall displacement δ of the filler from it equilibrium x will lead to an increase  of the total energy of the sys tem.

2 31 1( ) ( ) ( ) ( )2 6

E x E x E x E x

harmonic  term anharmonic term

In a  harmonic  approximation,  is  the spring  constant.( )E x

S mall displacement δ of the filler from it equilibrium x will lead to an increase  of the total energy of the sys tem.

2 31 1( ) ( ) ( ) ( )2 6

E x E x E x E x

harmonic  term anharmonic term

In a  harmonic  approximation,  is  the spring  constant.( )E x

0( )E xm

142 46.70 141 46.04 6.495K

113 17.18 112 16.87 3.819Na

91 42.56 90 41.62 14.55Sr

94 70.85 93 69.60 22.81Ba

43 18.88 42 18.04 28.74Yb

59 31.37 58 30.16 25.34Eu

55 25.18 54 23.72 23.27Ce

6837.426636.1023.07La

cm-1)k (N/m) cm-1)k (N/m)Mass (10-26 Kg)R

[100][111]

142 46.70 141 46.04 6.495K

113 17.18 112 16.87 3.819Na

91 42.56 90 41.62 14.55Sr

94 70.85 93 69.60 22.81Ba

43 18.88 42 18.04 28.74Yb

59 31.37 58 30.16 25.34Eu

55 25.18 54 23.72 23.27Ce

6837.426636.1023.07La

cm-1)k (N/m) cm-1)k (N/m)Mass (10-26 Kg)R

[100][111]

• Multiple-element filling will scatter a broad range of lattice phonons,lower thermal conductivity, and improve ZT1-3

1. Shi, X., Zhang, X., Chen, L. D., and Yang, J., Phys. Rev. Lett.

95, 185503, 2005.2. Yang, J., Zhang, W., Bai, S. Q., Mei, Z., and Chen, L. D.,

Appl. Phys. Lett.

90, 192111, 2007.3. Shi, X., Kong, H., Li, C.-P., Uher, C, Yang, J., Salvador, J. R., Wang, H., Chen, L., and

Zhang, W., Appl. Phys. Lett.

92, 182101, (2008)

Filler Atoms in Skutterudites Rattle with Different Frequencies -

Theory

• Calculated resonant phonon frequencies are experimentally validated

Yb Eu Ba

La

Phonon DOS Measured by Inelastic Neutron Scattering –

Experiment

STEM Images of the Triple-Filled Skutterudites

[111] direction

STEM Images of the Triple-Filled Skutterudites

1.

X. Shi, et al. Appl. Phys. Lett. 92, 182101 (2008)2.

X. Shi, et al., submitted (2009)

T (K)200 400 600 800 1000 1200 1400

ZT

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

Bi2Te3

PbTe SiGe

Ba0.24Co4Sb12

Ba0.08Yb0.09Co4Sb12

Triple-filled

Yb0.12Co4Sb12

ZTave

= 1.2

• Ba0.08

La0.05

Yb0.04

Co4

Sb12.05 Ba0.10

La0.05

Yb0.07

Co4

Sb12.16

Results –

Highest ZT Achieved in Triple-filled Skutterudites

Design or Searching for New Clathrates

The basic principle for composition designs: Zintl-Klemm concept.

Reasonable charge state: -4 for Ni, -3 for Cu, -2 for Zn, and -1 for Ga.

X-ray and EPMA analysis indicate clathrate structure and composition.

STEM also confirmed clathrate structure.

EPMA composition

Ba8

Niy

Gaz

Ge46-y-z

[100] [111]

Ba8

Ni0.5

Ga14

Ge31.5

Presentation_name•

No defects or no second phases have been observed so far.10 nm

y0 1 2 3 4 5

-1.2

-1.0

-0.8

-0.6

-0.4

-0.2

Enhanced Thermopower

(2)

Significant ionized impurity scattering of electrons. H

~T

Ba8NiyGazGe46-y-zStrong charge distortion!

1/3( 3 / 2)S r n r=1.5: ionized impurity scattering;r=-0.5: acoustic scattering

=1.5: ionized impurity scattering;=-1.5: acoustic scattering

Acoustic scattering for Ba8

Ga16

Ge30Mixed electron scattering

ZT Designs

T (K)200 400 600 800 1000

Z (T

-1)

2.0e-4

4.0e-4

6.0e-4

8.0e-4

1.0e-3

1.2e-3

T (K)200 400 600 800 1000

ZT

0.0

0.2

0.4

0.6

0.8

1.0

1.2 Ba8Ni2.97Ga3.94Ge38.91

Ba8Ni1.9Ga8.04Ge35.94

Ba8Ni0.84Ga12.07Ge33.16

Ba8Ni0.32Ga13.63Ge31.71

Ba8Ni0.31Zn0.52Ga13.06Ge32.2

Ba8Ga16Ge30

Shifting ZT peaks at any temperature through adjusting the band gap.

Enhanced thermopower

and reduced lattice thermal conductivity.

ZT Improved more than 200% at low temperatures and 50% at high temperatures.

ZTmax

=1.2, 50% higher than single Ba8

Ga16

Ge30

.

1. X. Shi, J. Yang, and H. Wang, to be submitted.

2009•

Skutterudite-based TE module construction

•

Complete the initial subsystem prototype construction

2010•

Provide test data for initial TE subsystem

•

Finalize advanced modeling and upgrading based on design•

Finalize vehicle integration with TE waste heat recovery system and the necessary vehicle modification

•

Carry out dynamometer tests and proving ground tests for vehicle equipped with TE waste heat recovery subsystem

•

Demonstrate fuel economy gain using TE waste heat recovery technology

Future Work

Completed TE Generator design

Completed power electronics design

Skutterudite-based module in process

Prototype construction and installation in process

Record ZTmax

=1.7 and ZTave

=1.2 achieved

Average Output[W]

Maximum Output[W]

FTP-75349 957

HWFET595 813

US06808 1233

US06 w/bypass628 809

Summary