Transcript Developments in Thermoelectric Power Generation

Marlow Industries, Inc.
DEVELOPMENTS IN THERMOELECTRIC POWER
GENERATION TECHNOLOGY
Jim Bierschenk
Advanced Concepts in Semiconductor Materials and
Devices for Energy Conversion
December 7th and 8th Sheraton Washington North Beltsville, Maryland
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Marlow Industries, Inc.
a subsidiary of II-VI Incorporated
About Marlow Industries, Inc.
Headquarters: Dallas, TX (USA)
Industry:
Thermoelectric Solutions
Structure:
Operating Subsidiary
Founded:
1973
Employees
500+
Manufacturing:
Thermoelectric quality and performance
at industry competitive prices.
Dallas, Vietnam
About II-VI Incorporated
Headquarters:
Industry:
Saxonburg, PA (USA)
Materials
Structure:
Public/(NASDAQ) IIVI
Founded:
1971
Employees
>6000
FY10 Revenue
$345M
Marlow Industries- Dallas, TX
Center of Technical Excellence
II-VI named for their material origin
in the compounds listed under II
and VI columns on the periodic
table: Zn, Cd, S, Se, and Te.
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Marlow Vertical Integration
TEC
Assembly
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SubSystem
Assembly
TE Cooling Markets and Applications
Defense, Space & Photonics
 Thermal Night Sights
 Range Finders and Target Designators
 FLIR Calibration Systems
Telecommunications
 Long Haul Laser Transmitters and Pump Lasers
 Short and Mid Range Laser
Transmitters/Receivers
Medical
 Thermal Cyclers for Polymerase Chain
Reactions
 Liquid and air refrigerated
compartments for blood analyzers
Industrial
 Heated & Cooled automotive car seats
 Point-of-sale boxes/small refrigerators
 Semiconductor processing equipment
Consumer
 Water chillers, wine chillers, refrigerators
 Personal cooling – bedding, chairs, etc.
 Gaming Applications
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TE Cooling vs. Power Generation
Energy
Harvesting
Medical
Telecom
Industrial
Space
Defense
Direct
Power
Gen
Waste
Heat
Recovery
Automotive
Marlow
TE
Cooling
Many diverse markets/applications
Extensive product customization
Flexible manufacturing capability
Thermal & mechanical design capability
Highest performing suite of TE materials
Consumer
Marlow
TE
Power
Gen
CoGeneration
Material research driven by waste heat
recovery applications
Many diverse markets/applications
Extensive product customization
Flexible manufacturing capability
Thermal & mechanical design capability
High performance generator materials
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TE Power Generation
Application Areas
Energy Harvesting
Microwatt to low milliwatt power to perpetually power
wireless sensors
Heat Source/ColdSource
• Battlefield sensors
• Engine health monitoring
(temperature, vibration, etc)
Ambient Air
• Structural health monitoring Q
(aircraft, building, bridges, etc)
• HVAC controls
Direct Power Generation
Burn a hydrocarbon fuel to produce heat – convert heat
to electrical using TE Generator
• Battery Replace Technology
• Unattended Ground Sensors
• Soldier power
• Robot/UAV power sources
• Battery Chargers
• Auxiliary Power Units
Waste Heat Recovery
Convert heated waste exhaust streams to electric power
for improve efficiency
• Automotive WHR
• Improve fuel economy
& reduce CO2 emissions
• Minimize Fuel Consumption
on stationary generators
• Convert Industrial Waste Heat to Electricity
Co-Generation
Heat produced from burning high energy density fuel.
• Self-powered military equipment
• Tent heaters
• Cooking equipment (ration
tray heaters, griddles)
• Cleaner burning 3rd world
cook stoves
• Self powered fans for wood stoves and mosquito
catchers
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Marlow Power Generation
 Marlow’s power generation focus is to develop:
– Volume production processes for new high
temperature materials
– Volume production device assembly processes
– Single and multistage (cascade capability)
– Device and system level thermal and mechanical
modeling
– Material, device and subsystem test capability
– Understand long term reliability
 Focus on both low temperature (Bi2Te3) and high
temperature applications
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Energy Harvesting – Why Now?
Heat Source/ColdSource
 Evolution of low power sensors,
transmitters and power
management electronics have
made TE energy harvesting
practical
Q
Ambient Air
Energy harvesting (also known
as power harvesting or energy
scavenging)
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Thermoelectric Energy Harvesting
Thermal Components
Heat
Source
Thermoelectric
Generator
N
P
N
P
N
N
P
RLoad
Electrical Components
Power
Management
TSource
Step-up, Charging, Storage,
Voltage Regulation
ΔTHS
HSR
Heat
Sink
P
TH
Sensor
Transmitter
ΔTTEG
RTEG
TC
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ΔTCS
CSR
TAmb
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Optimal TEG Design
The optimal TEG design for an energy
harvesting application:
 Thermally matches the combined hot and cold
side thermal resistances
 Electrically matches the electrical load
m
RTEG ,t
HSR  CSR
1
RLoad
n
1
RTEG ,e
 Has sufficient couples to provide the minimum
threshold voltage for the step-up electronics at
the desired source-to-ambient ΔT
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Interdependence of Thermal and Electrical
The electrical load resistance
impacts the thermal
characteristics of the TEG

 TH
N


  n  1 R
RTEG ,t ,o
TEG ,e

2
RTEG ,t
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


1
Energy Harvester TEG Transition
Traditional small TE Cooler
Can Be used As Energy
Harvesting TEG
Examples Marlow Energy Harvesting Devices, many of which
were co-developed with Sandia National Lab
Prior to low threshold voltage electronics, low ΔT energy harvesting required:
• TEGs with hundreds of couples (V is proportional to # couples and ΔT)
• High thermal resistance (i.e. large TE element aspect ratios)
Today, with threshold voltages as low as 20 mV, low cost, traditional small TE
devices can be used
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Marlow High Temperature
TEG Strategy
 Enable a diverse array of thermoelectric
power generation applications and markets by
developing:
– Volume production capability of TE generator
devices that can operate to 500 C
– Volume production capability for a suite of mid
range TE materials
– Accurate thermal and mechanical modeling of
TEG modules and systems
– Test capabilities for materials, devices and
subsystems
– Quantified reliability
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Power Generation Materials
P Type Materials
N Type Materials
Bi2Te3
 What power generation materials does Marlow use?
– “High Temp” Bi2Te3 (both crystalline and MAM formats)
– “PbTe” P and N, TAGS
– P and N Skutterudites
 Internal and University funded research on other new materials
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Managing the ZT Envelope
Material A
– Elements made of single alloy
with graded composition
and/or doping
• Segmentation
capability
– Elements made of 2+ alloys
joined with metal layers that
prevent interaction
• Cascading
preferred
– Multistage module with
single P and N materials in
each stage
Proprietary
~ 1.0
ZT
• Functionally Graded
Materials
Material B
Temperature
Material C
“Traditional” high volume TE module assembly
processes used for TE Generator assembly




Single & cascade TE devices
Brazes used instead of solder
Screen print braze paste w/ flux
Wet paste 1-time reflow in CAB
Furnace
Prototype 50 mm square PbTe Module
 “Segmented” top ceramic to reduce
thermal stresses (i.e. diced into
smaller ceramic pieces after
assembly)
 Simple tools, minimal capital
equipment
Marlow CAB Furnace for Braze Assembly
 Common device assembly process for both PbTe and
Skutterudite materials (different barrier)
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Prototype TE Generators
2 stage Skutterudite/Bi2Te3 modules
50 mm square Skutterudite modules
2 stage PbTe/Bi2Te3
modules
25 mm square PbTe
modules
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TE Device Test Development
 In-house TEG efficiency tester
–
–
–
–
–
Vacuum or inert atmosphere
500 C capability
Up to 40 mm cross sections
Unique device calibration to quantify heat losses
Material Seebeck and resistivity tests to 500 C
 Production test capabilities using Harman
technique module tester at elevated
temperatures
 Cycling and constant temperature aging test
stand in development
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Device Level Modeling
 Equations governing thermoelectric
device behavior (Ioffe, Goldsmid,
etc) were derived assuming
constant TE material properties
 These fundamental equations were
re-derived without the underlying
assumption of constant material
properties
– Provides more accurate modeling of TE
coolers and power generators with large
ΔTs
– Validated with experiment and with full
3D thermoelectric simulations in ANSYS
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Experimental
ANSYS
Model Program
Numerical Refinement
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HS=85°C
0
-10
CS (C)
– For improved accuracy, these equations
are typically used with temperature
dependent properties
– For cooling, the equations lose accuracy
at large ΔT
No Heat Load
HS=50°C
-20
-30
-40
HS=25°C
-50
-60
1
1.2
1.4
1.6
1.8
2
2.2
Current (A)
d  dT 
d dT I 2 
kA
 IT

0


dx  dx 
dT dx
A
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2.4
Thermoelectric System Modeling
Total Power (W)
9
1400-1600
7
1200-1400
# Seg
5
1000-1200
800-1000
600-800
3
400-600
200-400
0-200
200
140
100
60
30
16
1
# Devices Per Segment
W/kg
9
16-18
14-16
7
12-14
# Seg
5
10-12
8-10
3
 Model Validation
– System test on engine
dyno for automotive
waste heat recovery
system
– Output matches Marlow
system model
prediction
6-8
4-6
# Devices Per Segment
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200
140
100
60
30
16
1
2-4
0-2
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DOE CRADA
Oak Ridge National Lab/Marlow
 Objective: “To evaluate materials and
devices for waste-heat recovery
applications in automotive and heavy
vehicle applications up to 500°C.“
 Project Goals:
– Thermoelectric and mechanical material
properties for TE material
– Thermal and mechanical material
properties for any supporting material
– Develop ANSYS models to evaluate TE
devices in automotive applications
– Develop life prediction models
– Experimental verification of models
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Task 1
Evaluate
Candidate
TEMs
Task 2
Evaluate
Supporting
Materials
Task 3
TED FEA
Modeling and
Verification
Task 4
Final Reporting
Power Generation
Benefits from Improved in Bi2Te3
 High ZT Inorganic Colloidal Nanocrystal
thermoelectric material
– Bulk material format addresses
a wide range of heat flux
applications
– Phonon blocking to reduce
lattice thermal conductivity
– Quantum confinement
enhancement of the Seebeck
coefficient
– Scalable, low cost material
fabrication process
Colloidally synthesized nanocrystals
in a host inorganic semiconductor
matrix
Electron
hopping
Low electrical resistance diffusion
barriers
Phonon
blocking
• Device format and design that minimizes all
thermal and electrical losses
– High voltage, low current
operation enabled by Buildin-Place TEC assembly
process
– Low electrical contact
resistance on a bulk TE
material
Compacted high ZT
bulk TE material
BIP TEC fabrication method
High ZT material  High ZT devices
Program: Active Cooling Module (ACM)
Program Mgr: Avi Bar-Cohen
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THANK YOU!
Marlow Industries, Inc.
10451 Vista Park Road
Dallas, TX 75283
Jim Bierschenk
214-342-4281
[email protected]
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