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1
Pyroelectric Energy Harvesting Devices
Student Design Team:
Trent Borman1, John Etherington2, Thomas Geske1, Joshua Grindeland2
Faculty Advisors & Clients:Scott Beckman1 and Sumit Chaudhary2
Donor:Pete Onstad (to foster EE/MSE senior design collaboration)
1 Department of Material Science and Engineering; Iowa State University; Ames, Iowa; USA2 Department of Electrical and Computer Engineering; Iowa State University; Ames, Iowa;
USA
MAY14-25
MAY14-252
Problem Statement
Convert waste thermal energy to electricity.
Design a system to utilize the pyroelectric effect in materials with high entropy transitions.
MAY14-253
Market Survey
• Waste heat is abundant• No clear industry leader in thermal energy to
electric energy conversion• Modern high entropy materials exceed bulk
ceramics in performance
5
Coupling Thermal and Dielectric Properties
MAY14-25
A pyroelectric crystal spontaneously changes polarization when its temperature is changed
The electrocaloric effect is when a crystal spontaneously changes temperature when its polarization changes
The pyroelectric effect allows us to convert between thermal energy and electrical energy
6
Basic Operation of Engines and Refrigerators
MAY14-25
Refrigerator
System
ThermalReservoir
(Cold)
ThermalReservoir
(Hot)
Environment
Work
MAY14-257
Basic Operation of Engines and Refrigerators
Engine
System
ThermalReservoir
(Cold)
ThermalReservoir
(Hot)
Environment
Work
MAY14-259
Common Engineering Principles• A material is used to transfer heat between
thermal reservoirs• Complementary adiabatic processes facilitate the
thermodynamic cycle
Equilibrate with hot thermal reservoir
Equilibrate with cold thermal reservoir
Adiabatic Transformation
Adiabatic Transformation
10 MAY14-25
Example: Perovskite pyroelectric crystal: ABO3
Figure courtesy of Dr. Beckman
BaTiO3
-ΔT
-ΔT-ΔT
12
The ordering of atomic scale dipoles causes a change in the entropy
The change entropy requires a change in heat
In an adiabatic system, this causes a change in temperature
MAY14-25
Why does this work?
Field Direction-ΔT
MAY14-2513
Pyroelectric vs. Thermoelectric• Oscillating thermal
cycle• Dipole orientation• Applied electric field• Exhibited by few
materials
• Static thermal gradient• Charge carrier motion• No applied field• Exhibited by all
materials
MAY14-2518
Functional Requirements
• Demonstrate the pyroelectric effect in liquid crystals and polymers
• Convert waste heat to electrical work• Measure properties of specimens• Design a switching and harvesting circuit• Expose pyroelectric device to a thermal cycle• Withstand 400V across element
MAY14-2519
Non-functional Requirements• Well documented for future work• Modular for varying pyroelectric materials• Scalable to significant current and power levels• Safety
MAY14-2520
Deliverables
• Pyroelectric specimens• Liquid crystal cells• P(VDF-TrFE) films
• Characterization circuit• Electrical property measurements
• Harvesting circuit• Microcontroller code
MAY14-2521
Risks
• High risk project utilizing new, unproven materials and techniques
• Potentially transformative for thermal energy harvesting industry
MAY14-2522
Work breakdownTrent Borman
-Group leader
-Liquid crystal device fabrication
-P(VDF-TrFE) device fabrication
-Material electrical property curves
-Management of bill of materials
John Etherington
-Project timeline
-Communication (weekly report)
-Control systems and control code
-Circuitry design
Joshua Grindeland
-Web page design
-Circuitry design
-Pspice circuit design
-Electrical device research
Tommy Geske:
-Bibliography and Sourcing
-Liquid crystal device fabrication
-P(VDF-TrFE) device fabrication
-Thermodynamic curve generation
MAY14-2523
System Block Diagram
Microcontroller
SwitchingControl
Produced EnergySource/Load Switching
Circuit
VHigh VLow
ΔQIndependent Frequency Adjustment
TempReading
Pyroelectric Material
Contact
Contact
Heat Transfer System(pyroelectric device housed
within)
MAY14-2524
Design Stages
1. Pyroelectric specimens2. Characterization circuit3. Harvesting circuit
1
2 3
25
Polymer Specimens• P(VDF-TrFE)• Spin coating• 1.2 micron thickness• ITO substrate• Pinholing shorts ITO to top
electrode• Process being refined
MAY14-25
26
Polymer Specimen Troubleshooting• Solvents• Atmospheric conditions• Contacts• Thickness
Currently in contact with a group which creates PVDF films at Nebraska
Purchasing commercial polymer films to test concepts
MAY14-25
MAY14-2527
Barium Titanate Multi-layer Capacitors• Backup if high risk organic materials do not work• Confirm functionality of harvesting circuit• Well documented in literature• Preliminary testing of BaTiO3 MLCs show high
breakdown resistance
28
Liquid Crystal Specimens
• Commercial cells• 5CB liquid crystal• Increasing polarization
with electric field• Frequency tuning
MAY14-25
Instec Inc. Type SA and SB Liquid Crystal Cell
Structure of 5CB Liquid Crystal
MAY14-2530
Liquid Crystal Troubleshooting• Applying 210V results in breakdown preventing the
voltage from rising above 150V in the future• 400V breakdown observed by other groups
• Solutions investigated• New liquid crystals (hygroscopic)• Other liquid crystals (longer chain length)• External contacts (prevent conduction)• Increase temperature (phase change)
32 MAY14-25
0.1µF
8MΩ
22kΩ VV
The values of the resistors and capacitor will be modified to match the various pyroelectric samples.
Characterization: Sawyer-Tower
33
Harvester: Switch-level Model
MAY14-25
PyroelectricHarvesting
Load
PyroelectricBeyond
Curie Temp
Harvesting Load
PyroelectricHarvesting
Load
PyroelectricHarvesting
Load
1 2
34
VLow
VLow VHigh
VHigh
Increase Applied Voltage
Heat Pyroelectric
Connect to Load
Cool & Connect to
Voltage
34 MAY14-25
Harvesting Circuit
vRL
100k
DeviceTemp
+-
USBPWR
RESET3.3v5vGNDGNDVIN
A0A1A2A3A4A5
AREFGND
1312
~11~10~9
8
7~6~5
4~3
2Tx> 1Rx< 0
POWER
ANALOG
DIG
ITAL
(PW
M~)
RESET
Arduino U
NO
ICSP
TMP36
+-
47k
240
100µ 330k
1k
100
100
Vcontrol
10kOffsetNull
Vs
Vs
10k 5M 1µ
Future Work - Concept SketchThe device consists of three
subsystems:
Mechanical/Heat Transfer – Piston, stepper motor, silicone oil, heat sink, heating band.
Material – Pyroelectric material and contacts.
Electrical – Thermocouples, harvesting circuit, switching circuit, and motor controller.
MAY14-2537
MAY14-2538
Conclusion
• Electrical characterization has preliminary results, but is an ongoing project
• Preliminary circuits designed• Heat transfer system will be explored later
MAY14-2539
Acknowledgements
• We would like to thank Scott Beckman and Sumit Chaudry for their role as our advisors
• We would like to thank our client Pete Onsted for his generous donation to foster collaboration between materials science and electrical engineering
MAY14-2541
Safety
• High voltages• Lockout tag out• Insulating gloves
• Temperatures• Heat resistant gloves• Oil resistant clothing• Safety goggles
• Chemicals• Chemical resistant gloves• Storage and disposal plan• Fume hood• Safety goggles
MAY14-2542
Cost Analysis – Liquid Crystals
Supplier Name Unit Quantity Price Subtotal
Sigma Aldrich4’-Pentyl-4biphenylcarbonitrile Gram 1 $ 72.30 $ 72.30
Sigma Aldrich4’-Hexyl-4biphenylcarbonitrile Gram 1 $ 90.20 $ 90.20
Sigma Aldrich4’-Octyl-4biphenylcarbonitrile Gram 1 $ 84.80 $ 84.80
Instec Inc.Homeotropic alignment LC cells Holders 20 $ 14.00 $ 280.00
Total $ 527.30
MAY14-2543
Cost Analysis – Polymer
Supplier Name Unit Quantity Price SubtotalDelta Technologies
ITO coated glass slides Piece 20 $ 8.00 $ 160.00
Piezotech PVDF-TrFE 70/30 Gram 2 $ 10.00 $ 20.00
Sigma AldrichN,N-Dimethylformamide Liter 1 $ 85.40 $ 85.40
Fisher Scientific
1oz/30mL Polypropylene Bottles 12ct Pack 2 $ 12.53 $ 25.06
Total $ 290.46
MAY14-2544
Cost Analysis – Lab Supplies
Supplier Name Unit Quantity Price SubtotalFisher Scientific
Acetone (Certified ACS) 4L Bottle 1 $ 22.06 $ 22.06
Fisher Scientific
Methanol (Certified ACS) 4L Bottle 1 $ 16.12 $ 16.12
Fisher Scientific Best Butyl II Gloves Pair 1 $ 50.47 $ 50.47 Fisher Scientific
4.4 x 8.4 Lint Free Wipers 280ct Box 2 $ 3.82 $ 7.64
Fisher Scientific
Cotton-Tipped Wooden Applicators 1000ct Pack 1 $ 7.71 $ 7.71
Fisher Scientific
Graduated Disposable Pipettes 500ct Box 1 $ 14.29 $ 14.29
MAY14-2545
Cost Analysis – Lab Supplies
Supplier Name Unit Quantity Price SubtotalChem Stores
Disposable Nitrile Gloves 50pr/box Box 2 $ 6.04 $ 12.08
Ted Pella Inc.
Carbon Conductive Sheet Pack/10 1 $ 39.75 $ 39.75
Ted Pella Inc.
Copper Conductive Tape Roll 1 $ 41.25 $ 41.25
Ted Pella Inc.
Double Sided Kapton Tape Roll 1 $ 52.10 $ 52.10
Ted Pella Inc.
PELCO Water Based Carbon Paint 50g Bottle 1 $ 9.95 $ 9.95
Ted Pella Inc.
PELCO Colloidal Silver Paste 25g Bottle 1 $ 59.50 $ 59.50
TOTAL $ 332.92
MAY14-2546
Cost Analysis - ElectricalSupplier Name Unit Quantity Price Total
Sparkfun Arduino Uno Board 1 $ 29.95 $ 29.95
Digkey 35V - 1uF - MLC - X7R Capacitor 5 $ 0.23 $ 1.13
Digikey DC/DC 1kV converter Unit 1 $ 189.02 $ 189.02
Digikey Transistor Optocoupler 6-DIP 10 $ 0.94 $ 9.40
Digikey 3 Row solderless BB Board 1 $ 122.04 $ 122.04
Digikey Temperature Sensor Unit 3 $ 1.42 $ 4.26
DigikeyK-type Temperature Probe Unit 3 $ 14.95 $ 44.85
DigikeyK-type Thermocouple female sockets Unit 3 $ 7.10 $ 21.30
Digikey AC/DC wall pack Unit 1 $ 4.68 $ 4.68
TOTAL $ 426.63
48
Manual Heat Transfer System
• Manual rotation between cold and hot plates.
Figure from Olsen Journal of Energy (1982)
MAY14-25
49
Regenerative Heat Transfer System
Figure from Olsen Journal of Energy (1982)
Utilize a series of materials with a gradient of transition temperatures to maximize efficiency
MAY14-25
50
Automated Heat Transfer System
Figure from Olsen, Bruno, Briscoe, Dullea Ferroelectrics (1984)
MAY14-25
51
Polymer Spin Coating
• 3-4 drops of solution.• 5 wt% at 750-1250 rpm for
30-45s.• 10 wt% at 2000-3000 rpm for
30s, and 750 rpm for 60s.• 10 wt% at 3000 rpm for 30s
has uniform 1.2 micron thickness.
• Annealed for 30m at 80°C
MAY14-25
52
Preliminary Polymer Characterization
0 100 200 300 400 500 6000
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
P(VDF-TrFE) Polarization - Electric Field
250 kV/cm 150 kV/cm
Electric Field (kV/cm)
Pola
riza
tion
(μC/
cm2)
MAY14-25
54
Liquid Crystal Material
• Nematic liquid crystals were chosen due to their significant entropy change.
• 4'-Pentyl-4-biphenylcarbonitrile (5CB) was chosen due to literature on electrocaloric effect.
• 4’-Hexyl-4biphenylcarbonitrile, and 4’-Octyl-4biphenylcarbonitrile were also purchased for their higher transition temperature.
Structure of 5CB Liquid Crystal
MAY14-25
55
Preliminary Liquid Crystal Characterization
• Shows increasing polarization with increasing field as expected.
• Max polarization should occur at max field.
-600 -400 -200 0 200 400 600 800-2.5
0
2.5
5
7.5
10
12.5
15
17.5
20
22.55CB Polarization vs Electric Field
200 kV/cm 300 kV/cm 400 kV/cm 500 kV/cm600 kV/cm
Electric Field (kV/cm)
Pola
riza
tion
(μC/
cm2)
MAY14-25
56
Ceramic Nanosheets
• Liquid crystal holders• Preliminary characterization in
progress
Nakato et al.Journal of Physical Chemistry C (2011)
MAY14-25
MAY14-25
• Arduino Uno• Meets our specification• Low cost• Large user community,
base code• Compatible with our
stepper motor and driver
Isolator Trigger & Stepper Control
Thermocouples
57
Microcontroller
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