solid-state energy conversion overvie · 2014-03-18 · vehicle technologies program...
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Vehicle Technologies Program eere.energy.gov
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Solid-StateEnergy Conversion Overview
John W. FairbanksDepartment of EnergyVehicle Technologies
Annual Merit ReviewJune 11, 2010
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Overview
• Potential of Thermoelectric Applications in Vehicles
• Thermoelectric Materials
• Vehicular Thermoelectric Generators
• Vehicular Thermoelectric Air Conditioner/Heater
• Summary
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Vehicular ThermoelectricGenerators (TEG’s)
•Generate Electricity Without Introducing any Additional Carbon into the Atmosphere
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Vehicular Thermoelectric Air Conditioner/Heater (TE HVAC)
• Maintain Vehicle Occupant Comfort With Major Reduction of Fuel Use
• Eliminate Vehicular Use of R134a Refrigerant Gas which has 1300 times Greenhouse Gas Effect as CO2, the Primary Greenhouse Gas of Concern
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Front View Rear View
First Application of Thermoelectric Generator in Vehicle
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Modular HVACVariable speed compressor more efficient and serviceable3X more reliable compressor no belts,
no valves, no hoses leak-proof refrigerant lines instant electric heat
StarterGenerator
MotorBeltless engine
product differentiation improve systems design flexibility more efficient & reliable accessories
Shore Powerand InverterSupplies DC Bus Voltage from 120/240 Vac 50/60 Hz Input Supplies 120 Vac outlets from battery or generator power
Down ConverterSupplies 12 V Battery from DC Bus
AuxiliaryPower Unit
Supplies DC Bus Voltage when engine is not
running - fulfills hotel loads without idling main engine
overnight
Compressed Air ModuleSupplies compressed air for brakes and ride control
Electric WaterPump
Electric Oil PumpVariable speed
Higher efficiency
Truck ElectrificationElectrify accessories
decouple them from engineMatch power demand to real time need
Enable use of alternative power sources
Beltless or More Electric Engine
Higher reliability variable speedfaster warm-up less white smoke
lower cold weather emissions
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Current TE Materials
P-type TE material N-type TE material
Ref: http://www.its.caltech.edu/~jsnyder/thermoelectrics/
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81017 1018 1019 1020 1021
α σ
Carrier Concentration
Tota
l ΚZT
insu
lato
r
met
al
semiconductor
Unusual Combinationof Properties
TE Materials Performance:Figure of Merit (ZT)
σ 2
ZT =α
(κe + κL)• T
Seebeck coefficientor thermopower
(∆V/∆T)
Electrical conductivity
Total thermal conductivity
σ α2α
σ
κ
ZTmax
κL
κe
σα2 = Power Factor
σ= 1/ ρ = electrical conductivity
ρ = electrical resistivity
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Nanoscale Effects for Thermoelectrics(courtesy Millie Dresselhaus, MIT)
PhononsΛ=10-100 nm
λ=1 nm
ElectronsΛ=10-100 nmλ=10-50 nm
Electron Phonon
Interfaces that Scatter Phonons but not Electrons
Mean Free Path Wavelength
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Atomic Structure of Skutterudites
Cobalt atoms form a fcc cubic latticeAntimony atoms are arranged as a square planar ringsThere are 8 spaces for the Sb4 units6 are filled and 2 are empty
CoSb3 [Co8(Sb4)6]
RxCoSb3
Atoms can be inserted into empty sites. Atoms can “rattle” in these sites – scatter phonons and lower the lattice thermal conductivity.
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111. 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
• Ba0.08La0.05Yb0.04Co4Sb12.05ο Ba0.10La0.05Yb0.07Co4Sb12.16
Highest ZT Achieved withTriple-filled Skutterudites
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Key Element 1: Materials. Key Element 2: Thermal management. Key Element 3: Durability. Key Element 4: InterfacesKey Element 5: Heat sink design. Key Element 6: Metrology.
DOE/NSF Partnership inThermoelectrics
University/industry collaboration, $9M/yr over 3 yearsLOIs were due May 21, 2010Proposals due June 22, 2010
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Com
bust
ion 30%
Engine
Vehicle Operation10
0%
40% Exhaust
Gas
30%Coolant
5% Friction & Radiated
25Mobility &
AccessoriesGas
olin
e
Gas
olin
ega
solin
e
Typical Waste Heat from Gasoline Engine Mid Size Sedan
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ZT
0.1
0.2
1
700
500
300
Temperature [
C]
exhaust gas temperature
10
0.10
1.00
10.00
100.00
500 1000 1500 2000 2500 3000 3500 4000 4500
-750
-550
-350
-150
50
250
450
650
0.5
400
600
ZT (1000W)
ZT (500W)
Distance behind three way catalyst [mm]500 1000 1500 2000 2500 3000 3500 4000 45000
0
BMW 530iA at 130 km/h, Exhaust gas back pressure limited to 30mbar at 130km/h
Max hot side temperature of a module
SI Engine Exhaust Temperature Profile with Potential TEG Locations
Slide courtesy of BMW
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TEG‘s are Ideally Compatible with Regenerative Braking
BSST TEG (prognosis)
BMW TEG 2007
Slide courtesy of BSST
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-
BMW X-6
Courtesy of GM
Demonstration TEGs In Ford Fusion,BMW X6 and Chevy Suburban
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17116i 530dA 750iA
190 W2%
330 W3,5%
390 W4%
750 W6%
1000 W8%
Average demand for electric power
Fraction of electricity on total FC.
NEDC customer NEDC customer NEDC customer
Thermoelectric Power Generation –The Next Step for CO2 Reductions
400W4%
Source: BMW Group
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BMW integrating a TEG with the EGR cooler of a Diesel engine.
The infrastructure for a TEG (water cooling, by-pass, exhaust-flap) is available in today‘s EGR coolers
BMW Exhaust Gas Recirculation(EGR)-TEG
Source: BMW Group
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BMW Diesel Engine EGR TEG.
Source: BMW Group
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BMW EGR-TEG.
Source: BMW Group
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BMW EGR-TEG.
Source: BMW Group
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• Develop test protocols and metrics for real-world automotive TE HVAC system usage
• Use CAE, thermal comfort models, and subject testing to optimize heating/cooling node locations
• Develop high-efficiency advanced thermoelectric materials and assemblies
• Design, integrate, and validate performance of a production prototype TE HVAC in a demonstration vehicle
TE HVAC Approach
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Zonal Thermoelectric Air Conditioner/Heater (HVAC) Concept
Zonal TE devices located in the dashboard, headliner,A&B pillars and seats / seatbacks
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Thermoelectric HVAC Advantages for PHEV, HEV, EV or FC Vehicles
• Occupant Heating During Battery Propulsion(No Engine Heat)
– Resistance Heating InefficientOccupant Cooling– Electric Compressor Refrigerant Gases
> Need R134-a ReplacementThermoelectric HVAC Zonal Concept
> Cooling COP 1.5 Augment or Replace Compressed Gas Unit
> Heating COP 2.5Replace Resistive Heaters
Typical COP 1.0
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Battery Temperature Impacts PHEV, HEV and EV Performance and Service Life
Temperature affects battery operation• > Round trip efficiency and charge acceptance• > Power and energy• > Safety and reliability• > Life and life cycle cost
Battery temperature impacts vehicle performance, reliability, safety, and life cycle cost
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• Thermoelectric Generator providing nominal 5-6% fuel economy gain augmenting smaller alternator
• “Beltless” or more electric engines• Thermoelectric HVAC augmenting smaller A/C
• Thermoelectric Generators installed in diesel or gasoline engine exhaust– 55% efficient heavy duty truck engine– 50% efficient light truck, auto
• Thermoelectric Generators and HVAC w/o alternators or A/C
• Aluminum/Magnesium frame & body replacing steel(Process waste heat recovery) mass market cars
• 35% efficient Thermoelectrics w 500 0C ∆T– Replace Internal Combustion Engine (ICE)– Dedicated combustor burns any fuel
{
Near Term(3-5 yrs)
Mid Term(6-15 yrs)
{
Long Term(16-25 yrs) {
Vehicular Thermoelectric Application Possibilities