Thermoelectric Vehicular Applications Status Mid 2009 John W. Fairbanks Department of Energy Vehicle Technologies August 12, 2009 MIT-NESCAUM Symposium on Energy Dedham, MA
International Thermoelectric Conference 2009 Frieburg, Germany
Thermoelectric Generator and HVAC
TE materials performance: Figure of Merit (ZT) [courtesy Oregon State] Electrical conductivity Seebeck coefficient or thermopower ( V/ T) Unusual Combination of Properties ZT 2 e L ) T semiconductor e Total thermal conductivity Total L ZT max Power Factor ZT insulator metal electrical conductivity electrical resistivity 10 17 10 18 10 19 10 20 10 21 Carrier Concentration
Nanoscale Effects for Thermoelectrics (courtesy Millie Dresselhaus, MIT) Interfaces that Scatter Phonons but not Electrons Mean Free Path Wavelength Electrons =10-100 nm =10-50 nm Phonons =10-100 nm =1 nm Electron Phonon
Crystal Structure of Skutterudites Courtesy Oregon State Cobalt atoms form a fcc cubic lattice Antimony atoms are arranged as a square planar rings There are 8 spaces for the Sb 4 units 6 are filled and 2 are empty CoSb 3 [Co 8 (Sb 4 ) 6 ] Atoms can be inserted into empty sites. Atoms can rattle in these sites scatter phonons and lower the lattice thermal conductivity. R x CoSb 3
Available Energy in Auto Engine Exhaust
Potential Thermoelectric Heat Sources Vehicle Operation Gasoline gasoline Gasoline 100% Combustion 30% Engine 5% Friction & Radiated 25 Mobility & Accessories 30% Coolant 40% Exhaust Gas Spark Assisted Gasoline internal Combustion Engine (Light Truck or Passenger Vehicle)
Exhaust Flow and Temperatures for a 4- Cylinder Engine EXHAUST GAS FLOW RATE (kg/s) 0.06 0.05 0.04 0.03 0.02 0.01 EXHAUST MASS FLOW EXHAUST GAS TEMPERATURE COOLANT TEMPERATURE 1200 LD9 ENGINE -- EPA FTP CYCLE 1000 800 600 400 200 TEMPERATURE (K) 0.00 0 500 1000 1500 2000 2500 3000 TIME (SEC) 0 There are tens of kw heat energy in the exhaust & coolant
Thermoelectric Modules optimized for Thermal Zones Zone 1 Zone 2 Zone 3
TEG Candidate Materials 2005
Highest ZT Achieved in Triple-filled Skutterudites 1.8 1.6 Triple-filled Ba 0.08 La 0.05 Yb 0.04 Co 4 Sb 12.05 Ba 0.10 La 0.05 Yb 0.07 Co 4 Sb 12.16 1.4 ZT ave = 1.2 ZT 1.2 1.0 0.8 0.6 Bi 2 Te 3 Ba 0.08 Yb 0.09 Co 4 Sb 12 Ba 0.24 Co 4 Sb 12 Yb 0.12 Co 4 Sb 12 PbTe SiGe 0.4 0.2 0.0 200 400 600 800 1000 1200 1400 T (K) 1. X. Shi, et al. Appl. Phys. Lett. 92, 182101 (2008) 2. X. Shi, et al., submitted (2009)
TE Power Generation from Engine Waste Heat Heat Rejection Waste Heat > 60% T H 500 C T C 110 C TE Devices Carnot Efficiency C T H T C T H TE Efficiency Exhaust 500 C T T H C T H 1 ZT 1 1 ZT T C TH Waste Heat Recovery Goal > 10% Increase in fuel economy
Installed Thermoelectric Generator on Heavy Duty Truck Front View Rear View
Beltless or More Electric Engine Modular HVAC Variable speed compressor more efficient and serviceable 3X more reliable compressor no belts, no valves, no hoses leak-proof refrigerant lines instant electric heat Shore Power and Inverter Supplies DC Bus Voltage from 120/240 Vac 50/60 Hz Input Supplies 120 Vac outlets from battery or generator power Truck Electrification Electrify accessories decouple them from engine Match power demand to real time need Enable use of alternative power sources Starter Generator Motor Beltless engine product differentiation improve systems design flexibility more efficient & reliable accessories Auxiliary Power Unit Supplies DC Bus Voltage when engine is not running - fulfills hotel loads without idling main engine overnight Down Converter Supplies 12 V Battery from DC Bus Compressed Air Module Supplies compressed air for brakes and ride control Electric Water Pump Higher reliability variable speed faster warm-up less white smoke lower cold weather emissions Electric Oil Pump Variable speed Higher efficiency
DOE Vehicular Thermoelectric Generator Projects Competitive Award Selections (March 2004 RFP) Awardees Additional Team Members High Efficiency Thermoelectric General Motor Corporation and General Electric BSST, LLC. Michigan State University, University of Michigan, University of South Florida, Oak Ridge National Laboratory, and RTI International Visteon, BMW-NA, Ford, Marlow Industries NASA Jet Propulsion Laboratory Cummins Engine Company Tellurex, Iowa State
BMW s Electric Water Pump Improves Fuel Economy 1.5 to 2.0 %
BMW Series 5, Model Year 2011, 3.0 Liter Gasoline Engine w/ Thermoelectric Generator
TEG is ideally compatible with Regenerative Braking BSST TEG (prognosis) BMW TEG 2007 Slide courtesy of BSST
TEG Installed in BMW Series 5 Test Vehicle
Thermoelectric Waste Heat Recovery. BMW Sedans 1000 W 8% Average demand for electric power Fraction of electricity on total FC. 750 W 6% 390 W 330 W 3,5% 4% 190 W 2% NEDC customer NEDC customer NEDC customer 116i 530dA 750iA Slide courtesy of BSST
Program Flow Chart GM s Inputs Exhaust: T H, T C, flow & fluid properties Radiator: T H, T C, flow & fluid properties Elec. Load: Effective R, V req, Requirements: Cost, Power, Life GE s System Model Device config. Structure / design Heat transfer Hot & cold exchangers Interfaces Power conditioning DC/DC converter Materials Dev. (T), (T), (T) Cost & mass Geom. req. Output cost mass, P, power % FE Savings GM s FE Tools
GM TE Generator on a Chevy Suburban
Automotive (TE HVAC) Thermoelectric Heating Ventilation and Air Conditioning Competitive Awards to Ford and GM Co-Funded with the California Energy Commission Develop TE Zonal or Distributed Cooling/Heating System Maintain Occupant Comfort without Cooling Entire Cabin Reduce Energy used in Automotive HVAC s by 50% Eliminate all Toxic, Greenhouse and Flammable Gases Associated with Automotive HVAC
Zonal HVAC System Zonal TE devices located in the dashboard, headliner, A&B pillars and seats / seatbacks
A Battery Temperature Control System Vent Control Optional Heat Vents With Controls Battery Temperature Control Unit Battery Temperature Temp Battery Thermoelectric Power Control Heater/cooler Cooling or Heat Collection Fins Battery Thermal Enclosure Battery to Thermoelectric Unit Thermal Interface significant warranty cost savings improved battery reliability improved battery efficiency & performance enables more flexible packaging
Vehicular Thermoelectric Hybrid Electric Powertrain Exhaust Air Compressor Fuel Pump: Solid, liquid, gas Thermoelectric Multi-Fuel Combustor Thermoelectric Electric Propulsion Motor 440V Transmission Gear Box & Differential Radiator Coolant Pump Driver Demand Electric Power Conditioning & Control 12V Electrical Energy Storage (Batteries or Ultracapacitors) 12V Vehicle Electrical System
Vehicular Thermoelectric Application Possibilities Near Term (3-6 yrs) { Thermoelectric Generator providing nominal 10% fuel economy gain augmenting smaller alternator Beltless or more electric engines Thermoelectric HVAC augmenting smaller A/C Mid Term (7-15 yrs) { { Long Term (16-30 yrs) 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 0 C T Replace Internal Combustion Engine (ICE) Dedicated combustor burns any fuel
DOE s Thermoelectric Program Thermoelectrics They Are Not Just For Outer Space!!! Thank You