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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
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