Direct Energy Conversion - Stanford University · PDF fileDirect Energy Conversion Gang Chen...
Transcript of Direct Energy Conversion - Stanford University · PDF fileDirect Energy Conversion Gang Chen...
––WARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MITWARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MIT
Direct Energy Conversion
Gang Chen
Mechanical Engineering DepartmentMassachusetts Institute of Technology
Office: Room 3-260Tel: 617-253-0006
Email: [email protected]: http://web.mit.edu/nanoengineering
––WARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MITWARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MIT
Direct Thermal-to-Electric Energy Conversion Technologies
Thermoelectric Converter
Thermionic Converter
ThermophotovoltaicConverter
––WARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MITWARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MIT
Thermionic Power Generation
• Electron Distribution isf(E) ~ exp(-E/kBT)
• Ec, Ea are working functionsat cathode and anode
• Only electrons with energylarger than working function or barrier height can flow from one electrode to another
EXTERNAL LOAD
CATHODE ANODE
E E
Ec Ea
Tc Tae
EXTERNAL LOAD
CATHODE ANODE
E E
Ec Ea
Tc Tae
––WARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MITWARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MIT
Performance of Thermionic Converters
USSR TOPAZHatsopoulos and Kaye, JAP, 1958
––WARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MITWARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MIT
Challenges and Opportunities
• Space charge effects• Reliability• Low work function materials• Small gap devices• Field-emission enhancement
––WARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MITWARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MIT
THERMOPHOTOVOLTAICSH
eat S
ourc
e
Phot
ovol
taic
Ce l
ls
Filte
r
• Frequency Selective Emitter• Frequency Selective Filters• Photon Recycling Structures• Evanescent Wave Structures• High Efficiency PV Cells
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104
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EMIS
SIVE
PO
WER
(W/c
m2 µm
)WAVELENGTH (µm)
5600 K
2800 K
1500 K
800 K
EG
UselessUseful
––WARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MITWARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MIT
Potential Performance
Badalsaro et al., JAP, 89, 3319 (2001)Experimentally Demonstrated ~ 18%
––WARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MITWARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MIT
Challenges and Opportunities
• Spectral control– Selective emitters– Selective reflectors– Selective filters
• High efficiency cells• Thermal management• Near-field devices
––WARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MITWARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MIT
Photonic Crystal Selective Emitter
Si substrate
Alternating layers of tungsten and alumina
A. Narayanaswamy and G. Chen, PRB 70,125101, 2004
––WARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MITWARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MIT
Near Field Energy Conversion
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Pow
er a
bsor
bed
(Wcm
-2)
Vacuum gap (nm)
Power absorbed
Blackbody
0
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8 107
1.2 108
0.14 0.145 0.15 0.155 0.16
88.258.58.759
Flux
(Wm
-2eV
-1)
Frequency (eV)
Wavelength (µm)
d = 0 nmd = 1 nm
d = 5 nm
d = 10 nmSource (BN, SiC) PV material
SiC
––WARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MITWARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MIT
Near-Field Effect on Efficiency
Laroche et al., JAP, 100, 063704 (2006)
––WARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MITWARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MIT
Radioisotope Powered Thermoelectric Generators
Voyager 2(1977)
Voyager 1(1977)
Radioisotope Missions
Pioneer 11(1973)
Cassini(1997)
Pioneer 10(1972)
Galileo(1989)
Viking 1 & 2 (1975)Mars Pathfinder (1996)
(RHU’s only)
Ulysses(1990)
Transit 4 A(1961)
Transit 4 B(1961)
Transit 5BN-1(1963)
Transit 5BN-2(1961)
Nimbus 3(1969)
TransitTriad-01-0X
(1972)
LES 8(1976)
LES 9(1975)
Apollo 11 (1969)Apollo ALSEP (1969-1972)
10 Earth orbit (Transit, Nimbus, LES)7 planetary (Pioneer, Voyager, Galileo, Ulysses, Cassini)6 on lunar surface (Apollo ALESEP)4 on Mars surface (Viking 1& 2) 3 RHUs on Mars Pathfinder
Voyager 2(1977)
Voyager 1(1977)
Radioisotope Missions
Pioneer 11(1973)
Cassini(1997)
Pioneer 10(1972)
Galileo(1989)
Viking 1 & 2 (1975)Mars Pathfinder (1996)
(RHU’s only)
Ulysses(1990)
Transit 4 A(1961)
Transit 4 B(1961)
Transit 5BN-1(1963)
Transit 5BN-2(1961)
Nimbus 3(1969)
TransitTriad-01-0X
(1972)
LES 8(1976)
LES 9(1975)
Apollo 11 (1969)Apollo ALSEP (1969-1972)
Voyager 2(1977)
Voyager 1(1977)
Radioisotope Missions
Pioneer 11(1973)
Cassini(1997)
Pioneer 10(1972)
Galileo(1989)
Viking 1 & 2 (1975)Mars Pathfinder (1996)
(RHU’s only)
Ulysses(1990)
Transit 4 A(1961)
Transit 4 B(1961)
Transit 5BN-1(1963)
Transit 5BN-2(1961)
Nimbus 3(1969)
TransitTriad-01-0X
(1972)
LES 8(1976)
LES 9(1975)
Apollo 11 (1969)Apollo ALSEP (1969-1972)
10 Earth orbit (Transit, Nimbus, LES)7 planetary (Pioneer, Voyager, Galileo, Ulysses, Cassini)6 on lunar surface (Apollo ALESEP)4 on Mars surface (Viking 1& 2) 3 RHUs on Mars Pathfinder
GPHS Radioisotope Thermoelectric Generator
––WARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MITWARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MIT
Thermoelectric Power Generation
- +
I N P
I I
COLD SIDE
HOT SIDE
Figure of Merit:
kTSZT
2σ=
Thermal Conductivity
ElectricalConductivity
SeebeckCoefficient
COLD SIDE
HOT SIDE
––WARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MITWARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MIT
ZT DILEMMA
S
k
σZT
INSULATOR
SEMICONDUCTOR
SEMIMETAL
METAL
kTSZT
2σ=
Wanted:Phonon Glass / Electron Crystal
Methods of Reducing kIn Bulk Materials:
• Alloy, 1950s (Ioffe)• Rattlers, 1990 (Slack)
T vacant
square array of Pn(not to scale)
––WARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MITWARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MIT
State-of-the-Art in Thermoelectrics
0.0
0.5
1.0
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2.0
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3.0
1940 1960 1980 2000 2020
FIG
UR
E O
F M
ERIT
(ZT)
max
YEAR
Bi2Te3 alloy
PbTe alloy
Si0.8Ge0.2 alloy
Skutterudites(Fleurial)
PbSeTe/PbTeQuantum-dotSuperlattices(Lincoln Lab)
Bi2Te3/Se2Te3Superlattices(RTI)
AgPbmSbTe2+m(Kanatzadis)
Dresselhaus
––WARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MITWARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MIT
Nanocomposites Approach
– Increase interfacial scattering by mixing nano-sized particles.
– Enable low-cost, large scale application.
––WARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MITWARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MIT
Nanocomposite Synthesis
50 nm
Si Ge
––WARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MITWARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MIT
Electron Transport Over Potential Barriers
5 nm
––WARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MITWARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MIT
Thermal Conductivity of Si0.8Ge0.2
––WARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MITWARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MIT
Challenges and Opportunities
• Further improving ZT• System and device developments
––WARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MITWARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MIT
Comparison of Technologies
THERMALPOWERPLANT
AUTOMOTIVE ENGINES
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0.4
0.5
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1 10
POW
ER G
ENER
ATI
ON
EFF
ICIE
NC
Y
TEMPERATURE RATIO (T hot /T cold )2 3 4 5 6 7 8 9
CARNOT CYCLE 10
7
4
2
1
0.5
ZTm
THERMOELECTRICPOWER GENERATORS
STIRLINGGENERATOR
THERMIONICGENERATORS
THERMALPOWERPLANT
AUTOMOTIVE ENGINES
THERMALPOWERPLANT
0
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0.5
0.6
1 100
0.1
0.2
0.3
0.4
0.5
0.6
0
0.1
0.2
0.3
0.4
0.5
0.6
1 101 10TEMPERATURE RATIO (T hot /T cold )
2 3 4 5 6 7 8 9
CARNOT CYCLE 10
7
4
2
1
0.5
ZTm
STIRLINGGENERATOR
ThermoelectricConverter
IC Engine
ThermionicConverter
DieselPlant
PowerPlant
TPV
––WARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MITWARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MIT
Potential Applications in Nuclear Power Generation
• In combination with mechanical power generation
• Combinations of direct conversion technologies for high efficiency
––WARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MITWARREN M. ROHSENOW HEAT AND MASS TRANSFER LABORATORY, MIT
ACKNOWLEDGMENTS• Current Members
H. Asegun (Molecular Dynamics)V. Berube (hydrogen storage)J.W. Gao (nanofluids)S. Goh (nanowires and polymers)T. Harris (Thermoelectrics&Nanomaterials)Q. Hao (Thermoelectrics)D. Kramer (Solar thermoelectrics)H. Lee (Thermoelectric Materials)H. Lu (TPV and PV)A. Minnich (thermoelectrics)A. Muto (nanowires and thermoelectrics)A. Schmidt (ps pump-and-probe)S. Shen (near field transfer)Dr. M. Chieso (nanofluids)Dr. X. Chen (optics, Pump-and-Probe)
• Collaborators (partial list)M.S. & G. Dresselhaus (MIT, NW&CNT, Theory)J.-P. Fleurial (JPL, Thermoelectric Devices) J. Joannopoulos (MIT, Photonic Crystals)Z.F. Ren (BC, Thermoelectric Materials, CNT)X. Zhang (Berkeley, Metamaterials)
• Past Members (Partial List)Prof. A. Narayanaswamy (Columbia Univ)Dr. Zony Chen (McKinsey)Prof. C. Dames (Nanowires, UC Riverside)Prof. D. Borca-Tasciuc (Nanowires, RPI)Prof. T. Borca-Tasciuc (Thermoelectrics,RPI)Dr. F. Hashemi (Nano-Device Fabrication)Dr. A. Jacquot (TE Device Fabrication)Dr. M.S. Jeng (Nanocomposites, ITRI)Dr. R. Kumar (Thermoelectric Device Modeling)Dr. W.L. Liu (superlattice)Dr. D. Song (TE and Monte Carlo, Intel)Dr. S.G. Volz (MD, Ecole Centrale de Paris)Prof. B. Yang (TE and Phonons, U. Maryland)Prof. R.G. Yang (Nanocomposites, U. Colorado)Prof. D.-J. Yao (TE Devices, Tsinghua Univ.)Prof. T. Zeng (Thermionics, NCSU)
Sponsors: DTRA, DOE, NASA, NSF, ONR, Ford, Seagate, and others