Daniel CHAMPIER Thermoelectricity 1
Thermoelectricity
Université de Pau et des Pays de l'Adour France
Laboratoire des Sciences de l’Ingénieur Appliquées à la Mécanique
et au Génie Electrique (SIAME)
Laboratoire de thermique énergétique et procédés (LaTEP)
CHAMPIER Daniel
Daniel CHAMPIER Thermoelectricity 2
Thermoelectricity
other protagonists: Jean Charles Peltier 1785 – 1845
William Thomson 1824 – 1907 (Lord Kelvin)
General facts 1786 Alessandro Volta discovered thermoelectricity
1821 Thomas Johann Seebeck (1770 – 1831) presented experiments on thermoelectricity but
probably give incorrect explanation
1825 Oersted gave correct explanations of these experiments
Thermoelectricity is direct conversion of temperature differences to electric voltage and vice versa
Daniel CHAMPIER Thermoelectricity 3
Thermoelectricity
Seebeck effect : direct conversion of temperature differences to electric voltage
AB
V
T
V
+
T2
T1
A
B
B
A thermocouple made of two Conductors
Thermopower or Seebeck Coefficient : α
The voltage created by this effect is on the order of few to tens of
microvolts per Kelvin difference for metals and up to 1,000V for
semiconductors
Daniel CHAMPIER Thermoelectricity 4
Thermoelectricity
Peltier effect : direct conversion of electric current to heat flux When a current passes from one material to another, the energy transported by the electrons is
altered, the difference appearing as heating or cooling at the junction, that is as the Peltier effect.
AB
q
I
+
T2
T1
A
B
B
q
q
I
Peltier Coefficient : π
a source of EMF (Voltage source) is connected across the gap in
conductor B so as to drive a current around the circuit
Daniel CHAMPIER Thermoelectricity 5
Thermoelectricity
Kelvin relations AB ABT
ABA B
dT
dt
Other effects involved in thermoelectricity
The Thomson effect: heat absorption (or dissipation) by a material when subjected to temperature
difference and electrical current
I
q
Tc Th
T
Kelvin relations
q I T
The Joule effect
2q RI I
Q
Daniel CHAMPIER Thermoelectricity 6
Applications of Thermoelectricity
generate electricity “Seebeck effect”
measure temperature “thermocouple”
cool objects or heat objects “Peltier effect”
• Automotive
• Aircraft, ship
• Aerospace
• Remote Power (pipeline offshore)
• Biomass stoves
• Low power electronic
• Solar thermoelectric
Daniel CHAMPIER Thermoelectricity 7
Thermoelectricity
figure of merit
One couple of a seebeck module
2.Z
2. .TZT
Bi2Te3 ZT is about 1
dimensionless figure of merit ZT
σ is the electrical conductivity
λ is the thermal conductivity
ZT is a very convenient figure for comparing
the potential efficiency of devices using
different materials.
Values of ZT=1 are considered good
Daniel CHAMPIER Thermoelectricity 8
Thermoelectricity
TE modules individual couples connected electrically in series
Thermally in parrallel to enhance the effect
Semiconductor P and N
≈ 5 cm
≈ 4 mm
≈ 5 cm
Conductive strip
Daniel CHAMPIER Thermoelectricity 9
Thermoelectric (TE) Generators TEG
Heat
generator Available
heat
TE modules
Electrical power
(<10%)
Heat
source exchanger exchanger Heat
sink
Electronic converter Storage Battery
convert directly a very small part of the heat moving through them into electricity
2)( TPelec
Waste
Heat
Efficiency
is low
Daniel CHAMPIER Thermoelectricity 10
Basic results
These results will be explained in detail later
.
. . .Max 2 2elec
N SW T
8L
Dependence upon the temperature
difference across the thermoelements
Construction :
number of thermoelements
cross-sectional area
length of each element.
‘‘power factor’’ :
type of TE material
max .elec
thermal
W T 1 zT 1TcQ Th 1 zTTh
.2 2
z
efficiency is a function of zT (Dimensionless figure of merit)
( )Th TcT
2
Main goals Augment ZT
Augment T
Materials Research
Thermal Research
(exchangers)
Daniel CHAMPIER Thermoelectricity 11
Materials properties
Gao Min (Cardiff university)
Recent
Materials
(10 years)
Bi2Te3 ZT is about 1 the only commercial module available at large scale
Maximum temperature
Daniel CHAMPIER Thermoelectricity 12
Advantages of thermoelectric generators
• Direct Energy Conversion
• No Moving Parts
• No Working Fluids
• Maintenance-free Durability
• Noiseless Operation
Daniel CHAMPIER Thermoelectricity 13
Classification of generators
• recovery of thermal energy lost: optimization of wasted heat
• production in extreme environment: sources dedicated to TEG
• decentralized power generation: renewable energy sources
• microgeneration: all heat sources are acceptable
• thermoelectric solar: energy source : the sun.
Daniel CHAMPIER Thermoelectricity 14
Waste heat
1 quad=2.93 1011kWh=1.055x1018J
Daniel CHAMPIER Thermoelectricity 15
Automotive
Thermoelectric technology
for automotive Waste Heat Recovery
Prototypes :
-FIAT
-FORD
-GM
-BMW
- Amerigon
- Renoter (Renault truck Volvo …)
Daniel CHAMPIER Thermoelectricity 16
Thermoelectric technology for automotive Waste
Heat Recovery
Opportunity for Waste
Heat Recovery with
Thermoelectrics
Daniel CHAMPIER Thermoelectricity 17
Thermoelectric technology for automotive Waste
Heat Recovery
Sankey diagram for diesel vehicle
light duty trucks
3% efficiency
mean 0.9kW
Daniel CHAMPIER Thermoelectricity 18
Thermoelectric technology for automotive Waste
Heat Recovery
Emission target for passengers cars
130g/km for 2012
drastically reduced to 95g/km for 2020
Emission target for light duty trucks
175g/km for 2014
135g/km for 2020.
Fine and penalties to be paid by car
manufacturers that exceed EU CO2 limits
20€ per exceeding gram starting from 2012
95€ per exceeding gram starting from 2020
New CO2 emission performance standards
Daniel CHAMPIER Thermoelectricity 19
Thermoelectric technology for automotive Waste
Heat Recovery
400-500Wel means 6-7g/km CO2 reduction (Fiat Research Center)
small-medium gasoline engine at motorway driving condition is
characterized by a thermal power, in its exhaust gases, of 10kW at 600°C,
4-5% system conversion efficiency, which can be feasible with ZT=1-1.2
is enough to guarantee 400-500 Wel.
Conversion efficiency from fuel chemical energy to mechanical energy 25-27%
alternator efficiency from mechanical to electrical energy 60%
conversion efficiency from fuel chemical energy to electrical energy 15-16%
Electricity produced by alternator
Electricity produced by TEG
Daniel CHAMPIER Thermoelectricity 20
Automotive Requirements for a TE Generator
•Backpressure limit in TEG
•Exchanger must not disturb too much exhaust gases: pressure
drops very low (tens of a few millibars).
•Temperature limit for TE materials (add bypass for exhaust gases
•Durability test requirements
•Assembly requirements
•Control and sensor requirements
•Power conditioning (DC/DC converter)
•Recycling
•Price and Performance
Requirements
Daniel CHAMPIER Thermoelectricity 21
Alternator Replacement by a TEG
A TEG must be able to provide necessary power ( about 3kw 220A
14V) to the vehicle under extremely challenging conditions:
• Idle
• City drive cycle (Start-Stop)
• +50°C to -30°C ambient conditions
• Full accessory loads, including current spikes
• Reduce TOTAL fuel consumption, weight, and cost compared to
an alternator/battery system
Daniel CHAMPIER Thermoelectricity 22
Ford
Half-Heusler + Bi2Te3segmented TE elements
Anticipated power: ~500 Watts (peak)
TEG on a Ford Fusion with 3.0L V-6 Engine
the exhaust
Daniel CHAMPIER Thermoelectricity 23
Ford Packaging for Prototype TEG
TEG
FlexCoupling
Underfloor Catalyst
To Exhaust
To Exhaust
Daniel CHAMPIER Thermoelectricity 24
FORD
C. Maranville “ Thermoelectric opportunities for light-duty vehicles.” Ford Motor Company 2012
Daniel CHAMPIER Thermoelectricity 25
FORD : TEG performances for a 100km/h cruise
C. Maranville “ Thermoelectric opportunities for light-duty vehicles.” Ford Motor Company 2012
A bypass is necessary to protect the TEG
Anticipated power: ~500 Watts (peak) !!!
Temperature of gas
Welec
105km/h
Daniel CHAMPIER Thermoelectricity 26
BMW
2012 Boris Mazar State of the Art Prototype Vehicle with a Thermoelectric Generator
Bi2Te3
Bi2Te3
PbTe
Daniel CHAMPIER Thermoelectricity 27
BMW
BMW 535i (US)
Bi2Te3TEG (2007)
High-temperature TEG
Pmax=300W (2009)
2011 Dr. Andreas Eder Efficient and Dynamic –The BMW Group Roadmap for the Application of Thermoelectric Generators
Daniel CHAMPIER Thermoelectricity 28
Exhaust Gas Recirculation
reduces NOx emissions by
reducing the combustion
temperature in Diesel
engines.
Daniel CHAMPIER Thermoelectricity 29
BMW
The EGR-TEG unit consists of a TEG
section and a conventional cooler section.
conventional
cooler section.
TEG section
Daniel CHAMPIER Thermoelectricity 30
AMERIGON BSST (BMW et Ford)
Cylindrical TEG
TEGs were installed in a BMW X6 and a Ford Lincoln MKT with at least
450W of power output achieved in road tests for both vehicles.
D. Crane, “Thermoelectric generator performance for passenger vehicles” 2012
Daniel CHAMPIER Thermoelectricity 31
GM
2011Meisner advanced thermoelectric material and generator technology for automotive waste heat at GM.pdf
Daniel CHAMPIER Thermoelectricity 32
GM project may 2011
This module could capture waste heat in car's exhaust and convert it to energy, improving fuel economy in a
Chevy Suburban by 3%.
Computer models show the device could generate 350 to 600 watts for city and highway driving, respectively.
General Motors Thermoelectric Generator
Vehicle Selection : Chevy Suburban
2011Meisner advanced thermoelectric material and generator technology for automotive waste heat at GM.pdf
Finalize design of prototype TEG
only Bi2Te3 modules by-pass valve set point temperature
for the heat exchanger is about 250°C.
Daniel CHAMPIER Thermoelectricity 33
GM : Instrumented TEG and Results
Temperature of the heat exchanger is
250°C for a temperature of exhaust gas
around 400°C
2011Meisner advanced thermoelectric material and generator technology for automotive waste heat at GM.pdf
150°C
Daniel CHAMPIER Thermoelectricity 34
GM : Instrumented TEG and Results
Temperature variation along the Teg //
to the exhaust gas flow is significant
Front 250° Middle 178° Rear 148°
Temperature variation transverse to
the exhaust gas flow is low < 3°C
2011Meisner advanced thermoelectric material and generator technology for automotive waste heat at GM.pdf
Coolant
50°C
1,3 W avec
un HiZ20
209$ !!!!
150°C
11 W avec
un HiZ20
Daniel CHAMPIER Thermoelectricity 35
2011Meisner advanced thermoelectric material and generator technology for automotive waste heat at GM.pdf
GM : Instrumented TEG and Results
Open circuit voltage are consistent with a 50°C smaller ΔT than
measured between the heat exchanger and the coolant
Computer models show the device could
generate 350 to 600 watts
Daniel CHAMPIER Thermoelectricity 36
G. P. Meisner, “Skutterudite thermoelectric generator for automotive waste heat recovery,” in 3rd Thermoelectrics Applications Workshop 2012
GM : future work
Expected Output power 425 Watts !
Improved skutterudite TE materials
Refine TEG design :thermal and electrical interface, bonding …
Electrical power conditioning (avoid impedance mismatch)
First experiment 19W with few modules and small ΔT
extrapolated to 235 Watts in optimum conditions
Daniel CHAMPIER Thermoelectricity 37
Daniel CHAMPIER Thermoelectricity 38
Renault Trucks, Volvo
Choice of Silicide's
- N-type : Mg2Si
- P-type : MnSi1.77
Advantages disadvantages
Non-toxic materials Moderate ZT
Light density (2-4) Mg2Si type P not
available
Abundant raw materials Current doping of Mg2Si
in project
Support high exhaust
temperature (> 600°C)
P and N have different
mechanical properties
Successful lab. production of the legs for
the project prototype
2012 Luc Aixala RENOTER project presentation
Daniel CHAMPIER Thermoelectricity 39
Renault Trucks Joint Company -Volvo Group
•New efficient TEG design allowing screening of any novel materials
•1kW (trucks) and 300W (cars) targets achievable during this year (2011)
•Mass market application in sight but will take time
Daniel CHAMPIER Thermoelectricity 40
Aircraft waste heat
recovery Thermoelectric
Applications
Daniel CHAMPIER Thermoelectricity 41
Aircraft Thermoelectric Applications
Aircraft engine waste heat harvesting has large potential payoffs
How can Thermoelectric Contribute?
Turboprop
Turboshaft Turbofan
2009 James Huang,Boeing Research & Technology
Fuel Reduction
Preliminary analysis showed that 0.5% or more fuel reduction is achievable
Operating Cost Reduction
Average monthly fuel costs for U.S. commercial planes is $2.415B for the first
4 months of 2009 (Source: EIA)
A 0.5% fuel reduction : $12M monthly operating cost reduction
Advantages Disadvantages
•Provides electrical power from waste heat – no fuel
burn and no moving parts
• Operates over the entire aircraft flight envelope
• Operates independent of engines and does not
affect engine operations
•New technology and unproven
•Cost & efficiency; further development is needed
•Power output limited by available waste heat, space,
device efficiency.
Watt per kilo?
Permitted 0.15 kW/kg
Helicopter conical nozzle
Champier : 0.04kW/kg
Daniel CHAMPIER Thermoelectricity 42
Usage of Thermoelectric Generators on Ships
Ship transport generates a large amount of
waste heat
main engine (8-15 MW)
(heavy fuel oil)
auxiliary engines
incinerator
(waste oil : sludge representing 2% of oil
consumption of the main engine)
Workers at heavy cost .
Cold sink between 5°C and 28°C
available (seawater)
no problem with space and weight
Wasted heat used for
heating of heavy fuel oil
•Heating of accommodation areas
•freshwater generation
Work intermittently
Working time : 12h to 20h /day
Steam engine :
Needs a worker at
start and stop : heavy
cost
Thermoelectric
genrator
Kristiansen : incinerator 850kW, calculation : 38kW electric cost 2,7US$/W.
Daniel CHAMPIER Thermoelectricity 43
Waste heat recovery : conclusion
Automotive
Alternator + TEG : imminent
Replacement of alternator : challenge
Airplanes
More research is necessary …
ships
Promising
Daniel CHAMPIER Thermoelectricity 44
Electricity production in extreme environment
critical applications: a power source extremely reliable over very long periods.
extreme climatic conditions:
• very hot
• very cold
• very wet
• very dry.
Maintenance as low as possible
• helicopter access
•several hour trip
Maintenance does not exist in the case of space expeditions.
operation in a vacuum
vibrations.
insensitive to radiation
The cost of watt is not essential
Daniel CHAMPIER Thermoelectricity 45
Space applications
First use of a thermoelectric generator (Pb -Te) : 1961
navigation satellite Transit (1961) of the U.S. Navy.
SNAP-3 (Space Nuclear Auxiliary Power)
Electrical power~2,7 watts
worked for more than fifteen years
Daniel CHAMPIER Thermoelectricity 46
Space applications
RTG Radioisotope Thermoelectric Generator
Radioisotope Thermoelectric Generators, or RTGs convert the heat generated by
the decay of plutonium-238 (plutonium dioxyde 238PuO2) fuel into electricity using
devices called thermocouples.
http://solarsystem.nasa.gov/rps/rtg.cfm
GPHS : General Purpose Heat Source module
238Pu fuel pellet
Daniel CHAMPIER Thermoelectricity 47
Space applications
T. Caillat et al 23rd rd Symposium on Space Nuclear Power and Propulsion STAIF 2006Jet Propulsion Laboratory/California Institute of Technology
Daniel CHAMPIER Thermoelectricity 48
Space applications
T. Caillat et al 23rd rd Symposium on Space Nuclear Power and Propulsion STAIF 2006 Jet Propulsion Laboratory/California Institute of Technology
Daniel CHAMPIER Thermoelectricity 49
Space applications
http://solarsystem.nasa.gov/rps/rtg.cfm
Cassini’ RTG before mounting
Daniel CHAMPIER Thermoelectricity 50
Space applications
http://solarsystem.nasa.gov/rps/rtg.cfm
Curiosity’s Radioisotope Thermoelectric Generator
Daniel CHAMPIER Thermoelectricity 51
Space applications
Radioisotope Thermoelectric Generator RTG
Electric Power at beginning
of mission per RTG
Number of RTG
Mission destination year design
lifetime lifetime
Space Nuclear Auxiliary Power SNAP-3 PbTe
2,7 Watts 1 Transit Navigation satellite 1961 15 years
SNAP-19B RTG PbTe-Tags 28.2 Watts 2 Nimbus III meteorological satellite 1969
SNAP-19 RTG PbTe-Tags
42.6 Watts 2 Viking 1 Mars landers 1975 90 days 6 years
2 Viking 2 Mars landers 1975 90 days 4 years
40.3 Watts 4 Pioneer 10 Jupiter, asteroid belt 1972 5 years 30 years
4 Pioneer 11 Jupiter Saturn 1973 5 years 22 years
SNAP-27 RTG PbSnTe
70 Watts Apollo 12, 14,
15, 16 , 17 Lunar Surface
1969-72
2 years 5-8 years
Multi-Hundred Watt (MHW) RTG SiGe
158 Watts 3 Voyager 1 & 2 edge of solar system 1977 still operating over 30 years
General Purpose Heat Source (GPHS) RTG
SiGe 292 Watts
2 Galileo Jupiter 1989 14 years
3 Cassini Saturn 1997 still operating after 14 years
1 Ulysses Jupiter 1990 21 years
1 New Horizons Pluto, Kuiper Belt 2006 still operating after 6 years
Multi-Mission Radioisotope Thermoelectric Generator
MMRTG PbTe-Tags 110 Watts 1 Curiosity
Mars Surface 5 Aug 2012
2011 Expected 14
years
Daniel CHAMPIER Thermoelectricity 52
Space applications
Radioisotope Thermoelectric Generator
• compact
• Continuous power sources
• Used in deep space for several decades
• reliable
• Use nuclear fuel relatively easy to manipulate Curium-244
and Plutonium-238
• Materials used: PbSnTe, PbTe, TAGS, SiGe
Conclusion
Current research:
Improved performance of materials: reduced thermal conductivity of the
network
Zintl, skutterudites, couples segmented.
Daniel CHAMPIER Thermoelectricity 53
TEG for Remote Power
Daniel CHAMPIER Thermoelectricity 54
Remote Power Solutions
REJECTED
HEAT
500 Watts 24 Volts
Natural Gas 48m3/day
Propane 76L/day or 38kg/day
COOLING
FINS
EXHAUST
OUT
LOAD
FUEL IN
T
E
G
F
L
A
M
E
Oil or gas pipelines
Well sites
Offshore platforms
Telecommunications sites
Communications systems
….
Critical application requiring highly reliable power
Low maintenance required
Long life
Extreme climatic conditions (hot, cold, wet, dry)
Remote locations
Propane 38kg/day
Heating Value 50MJ/kg Energy per day= 1900MJ=527kW.h
500 W electric Energy per day= 12 kW.h Efficiency : 2.2 %
Daniel CHAMPIER Thermoelectricity 55
Remote Power Solutions
500 Watts 24 Volts
Natural Gas 48m3/day
Propane 76L/day or 38kg/day
Pipeline: 550 watts
communications system
Andes Mountains, Chile
Off shore: 200 watts
communications and safety
equipement, multiple systems
- Thailand
Critical application requiring highly reliable power
Low maintenance required
Long life
Extreme climatic conditions (hot, cold, wet, dry)
Remote location Telecommunications:50 watts
helicopter access only,
emergency communications system
- Rocky Mountains, Canada
Pipeline:
5000 watts for SCADA
communications and cathodic
protection of gas pipeline - India
Niche market for TEG
Daniel CHAMPIER Thermoelectricity 56
Remote Power Solutions
electrical output of a Model 5060 TEG
Maximum Power for an
electrical load between
0.4 and 0.9 ohm
Daniel CHAMPIER Thermoelectricity 57
Biomass stoves
Combined Heat and Power (CHP)
Decentralized electricity generation
Developing countries
Biomass primary energy source
(cooking, heating, domestic hot water)
Developed countries
Connection to the network is not always
economically attractive
Daniel CHAMPIER Thermoelectricity 58
Thermoelectric power generator for Biomass
Stoves
koolatron
Université de Pau et des Pays de l'Adour
Laboratoire des Sciences de l’Ingénieur Appliquées à la Mécanique
et au Génie Electrique (SIAME)
Laboratoire de thermique énergétique et procédés (LaTEP)
Non Governmental Organisation ‘Planète Bois’ Tarbes France
Daniel CHAMPIER Thermoelectricity 59
• Biomass energy is used for basic needs : cooking and heating
• They needs electricity for light, cellular phone and radio
• Biomass is burnt through open fire stoves – low efficiency forest destruction and global warming contribution
– high emissions of air pollutants health damaging
• “Planète Bois” is developing an improved multifunction biomass fired stove. combustion chamber is designed to achieve almost complete combustion of wood
A fan is necessary to increase the air/fuel ratio
Smoke can be extracted with a horizontal pipe avoiding the building of a vertical chimney
• Connecting these households to the power grid cost of building new landlines from US$300 to more than US$4000
cost of distribution of electricity from US$0.07 to US$5.1 per kWh
• thermoelectric generators are cost-effective options for these specific off-grid households.
1.4 billion people
without electricity
in developing countries
Thermoelectric power generator for Biomass
Stoves
Daniel CHAMPIER Thermoelectricity 60
Review of thermoelectric generators
for cooking stoves
Author Heat sink (cold side) Type of module * Power per
module
Nuwayhid 2003 Natural air cooling Peltier 1W
Nuwayhid 2005 Natural air cooling Seebeck 4.2W
Nuwayhid 2005 Heat pipes cooling Seebeck 3.4W
Lertsatitthanakorn 2007 Natural air cooling Seebeck 2.4 W
Mastbergen 2007 Forced air cooling (1W) Seebeck + 4W regulated
“BioLite” 2009 Forced air cooling (1W) Seebeck + 2 W
Champier “TEGBioS “ 2009 Water cooling Seebeck 5W
Champier “TEGBioS II“ 2010
Water cooling
Seebeck
9.5W
7.5 W regulated
Rinalde 2010 Forced water cooling (?W) Seebeck 10 W
Bismuth Tellurid (Bi2Te3)
* Peltier :
The temperature difference is limited due to the maximum temperature supported by the solder
The geometry is optimized for cooling and not for power generation.
* Seebeck
The hot side work at a temperature as high as 300°C continuously.
The geometry is optimized for power generation
Heat source : hot gas
Daniel CHAMPIER Thermoelectricity 61
“Planète Bois” cook stove
Biomass fired stove
10 kW wood consumption
2.4 kW are used in heating the water 4.5 kW are used in heating the room and inertia
0.9 kW is used for cooking
The idea is to put the TEG in a cogeneration system which
simultaneously provides electric power and heat for the hot water
Daniel CHAMPIER Thermoelectricity 62
“Planète Bois” Cook stoves
hot incoming combustion gas
pyrolyzing chamber
water tank 18 liters
Daniel CHAMPIER Thermoelectricity 63
SIAME prototype
The advantages of thermoelectric generator are :
It does not need extra energy from the stove.
• It will use the heat flux between the gas and the water tank
• It will only convert a small part into electrical energy.
It is incorporated into the cook stove:
• it requires no electrical link with the outside world, unlike solar panels, or
manipulation of battery.
The maintenance is very light:
• nothing is moving,
• everything is inside the house,
• only the battery needs to be changed at the end of its life.
The generator produces when the stove is on, day and night in good or in rainy
weather (monsoon period) unlike solar panel.
The battery does need to be oversized as each use of the stove recharges the battery
unlike solar system where you need to store energy for the cloudy days.
Daniel CHAMPIER Thermoelectricity 64
Laboratory prototype
0 400 800 1200 1600 2000 2400 2800 3200 36000
20%
40%
60%
80%
Eomax
Time (s)
Eo
THot
TCold
THotmax
80%
60%
40%
20%
0
Typical Cycle representative
of one hour combustion
SIAME prototype
Daniel CHAMPIER Thermoelectricity 65
Trial of TE generators at SIAME.
Cycle Laboratory
Cycle
one cooking Day 1
2 cookings
Day 2
2 cookings (1 long)
Electrical energy
produced
6.7 Wh
24 kJ
14.1 Wh 28.3 Wh 43.1 Wh
Use’s example* Fan, one phone
charge
2 hours of light
Fan, 2 phone
charges and about
4 hours of light
Fan, 2 phone charges
and 7 hours 20 min of
light
* Phone battery of 3.7V, 1050mAh and light consummation of 4W
Number of systems >5 >100 >1 000
Price (€) 205€ 122€ 72€ Economic
TE generators are cost-effective solutions for off-grid households.
Daniel CHAMPIER Thermoelectricity 66
And now?
Today Tomorrow
with TEG
Somewhere
in a village
Our laboratory
this work is supported by
Daniel CHAMPIER Thermoelectricity 67
Others prototypes
Study of modules properties TEGbios I TEGbios II
Study of contact resistances Study of heat exchange
with moving gas
Daniel CHAMPIER Thermoelectricity 68
thermoelectric generators for cooking stoves
Biolite
USB
2W 5V
Daniel CHAMPIER Thermoelectricity 69
Biolite
HomeStove and CampStove
Ghana
Lake Brassua (Maine)
129$
Daniel CHAMPIER Thermoelectricity 70
Combined Heat and Power (CHP) with TEG
Automatic Pellet Furnaces, especially Small Scale Combustion Units
Market
East of Europe and North-America
because of unreliable Electric Power Grids
Stove with TEG 400
Max: 8 kWth, 100 Wel
Air cooling
Boiler with TEG 400
Max: 12 kWth, 300 Wel
Water cooling
Outlook BIOENERGY 2020+
Daniel CHAMPIER Thermoelectricity 71
Combined Heat and Power (CHP) with TEG
Module 8cmx8cm
TEG
Biomass CHP
(pellets)
BIOENERGY 2020+
Location Wieselburg 100km from Vienna !
Decentralized production for decentralized utilization
Production of electricity during periods of high heat demand
and low offer of other renewable energies:
• During winter
• Whilst twilight or night
• During times without sun and wind
Fuel heat output: 10 kW
Nominal electric power: 200 - 400 W
• 8 plates, each with 2 modules
• Positioned around flame
• Heated from inside, cooled from outside
Daniel CHAMPIER Thermoelectricity 72
Combined Heat and Power (CHP) with TEG
Result Achieved
Useful Heat > 50%
Generator efficiency 3.5%
Electrical efficiency 1,7%
Electrical Power 170 W
Fuel heat : 10 kW
Prototype TEG 250 BIOENERGY 2020+
Daniel CHAMPIER Thermoelectricity 73
Autonomous Gas Heaters
2011 M. Codecasa Design and development of a teg cogenerator device integrated in self standing gas heaters
Heater 8kW
Thot 305°C
Tcold 125°C
Power 7.8W
Daniel CHAMPIER Thermoelectricity 74
Energy Harvesting for Low Power Electronics
http://www.micropelt.com
Modern wireless sensor modules require only ~100 W -10mW
Micropelt thermogenerator offers a high density of up to 100
thermoelectric leg pairs per mm2
200 C max.
Electrical:
•Thermo-Voltage: uTEG = 0.14 V/K
•Electrical Resistance: RTEG ~ 350
•Thermal Resistance: Rth = 12,5 K/W
Take a small portion of a lost flow of ‘primary’ energy, and convert it into a small flow of USEFUL
electrical energy.
Every technical process produces waste heat
4.2mmx3.3mmx1mm
Daniel CHAMPIER Thermoelectricity 75
Micropelt MPG-D751
5mW is enough for most microsensor
Energy Harvesting for Low Power Electronics
Daniel CHAMPIER Thermoelectricity 76
Energy Harvesting for Low Power Electronics
http://www.micropelt.com
Emerson WiHART
Differential Pressure Transmitter
ABB Technology Demonstrator
•Self-powered WirelessHART temperature
transmitter
•Fully integrated thermogenerators
•Powered by Micropelt TEG & boost technology
Applications :
Wireless sensors
Data loggers
Direct valve control
Wireless pneumatic control
Use heat from 15 mm pipe
Output power 3.5mw
at 60°C and ambiant 25°C
Daniel CHAMPIER Thermoelectricity 77
Solar Thermoelectricity
Daniel CHAMPIER Thermoelectricity 78
Solar Thermal to Thermoelectricity
Heat flux through a thermoelectric leg
Solar insulation: ~ 1 000 W/m2
Need to concentrate heat by ~100 times
25 W/m100.001
1001
L
ΔTλ
A
q
11K W.m1λ 0.001mL
100KΔT
Daniel CHAMPIER Thermoelectricity 79
Solar Thermoelectrics
Low materials cost and low capital cost, potentially high efficiency.
Key Challenges:
Develop materials with high thermoelectric figure of merit
selective surfaces that absorb solar radiation but do not
re-radiative heat.
Mildred Dresselhaus Massachusetts Institute of Technology
SiGe
Daniel CHAMPIER Thermoelectricity 80
Solar Thermoelectrics
Daniel CHAMPIER Thermoelectricity 81
Simplified Thermoelectric Equations and properties
Assumptions:
The material properties are temperature independent
Daniel CHAMPIER Thermoelectricity 82
Thermoelectric equations (single couple)
It will be assumed that all the heat flow between the source and sink takes place within the thermocouple. Thus, it will be
supposed that thermal radiation and losses by conduction and convection through the surrounding medium are negligible. The
two thermocouple branches in our model have constant cross-sectional areas. Thomson effects will be neglected.
For each branch of the thermoelectric module we have one thermoelectric flow (Seebeck ) and a heat flow (conduction)
p p p p
n n n n
dTI T S
dx(1)
dTI T S
dx
is the thermal conductivity of the material [W. m-1. K-1],
is the Seebeck coefficient of the material [V. K-1]
I is the norm of the electric current [A] which explains the minus sign in front . n
p
n
I
I
Thermal
x 0 L
Daniel CHAMPIER Thermoelectricity 83
Thermoelectric equations (single couple)
All the heat flow between the source and sink takes place within the thermocouple.
Thus, thermal radiation and losses by conduction and convection through the surrounding medium are negligible.
It is therefore possible to neglect the temperature variations along the axes y and z.
All this brings us to solve a one-dimensional problem along the x axis
The heat equation can be written in this case
1 T ²T q
a t x²heat generation by Joule effect with
I²q
S²
3
W
m
a = / cp.ρ is the thermal diffusivity
ρ is the specific weight
p
n
I
Thermal
x 0 x+dx
Heat equation in Cartesian Coordinates:
Net transfer of thermal energy into the
control volume (inflow-outflow)
p
T T T Tq c
x x y y z z t
•
Thermal energy
generation
Change in thermal
energy storage
conservation of energy to a differential control volume through which energy transfer is exclusively by conduction.
Cp is the specific heat capacity
control volume : a slice along x
ρ is the electrical resistivity
Daniel CHAMPIER Thermoelectricity 84
Thermoelectric equations (single couple)
We also consider the coefficients , ρ and to be constant. This assumption is possible when dealing with small changes and
if we choose an appropriate factor to the situation (that is to say, depending on the temperature range).
We have for each leg:
22p
p p 2p
22n
n n 2n
ITS
Sx2
ITS
Sx
( )
Then we solve the previous equation for each branch
p
n
I
Thermal
x 0 x+dx
The heat equation
1 T ²T q
a t x²with
I²q
S²
To simplify the problem, we will assume the steady state. The left term disappears.
²T q0
x²
²T I²0
x² .S²or
Daniel CHAMPIER Thermoelectricity 85
Thermoelectric equations (single couple)
22p
p p 2p
ITS 2
Sx( )
If we solve the previous equation for the branch p
( )
( )
2p
p pp
2p 2
p pp
ITS x B
x S3
IS T x x Bx C
2 S
Boundary conditions: T x 0 Th T x L Tcand
for x = 0 we have :
for x = Lp we have
p pC S Th
2 2p p
p p p p pp
I LS Tc B L S Th
2 S
2p p p p
p p
S Tc Th I LB
L 2 S
p
n
I
Thermal
x x+dx
L 0
Th Tc
Daniel CHAMPIER Thermoelectricity 86
Thermoelectric equations (single couple)
If we replace in (3)
p2p
p pp p
p p
LI x
S Tc Th2TS 4 1
x S L( . )
2 nn
n nn n
n n
LI x
S Tc ThT 2S 4 2
x S L( . )
and if we follow the same reasoning for the N-doped leg
2p p p p
p p
S Tc Th I LB
L 2 S p pC S Th
p
n
I
Thermal
x x+dx
L 0
Th Tc
2p
p pp
22n
p pn
ITS x B
x S3
IS T x x Bx C
S
( )
( )
Daniel CHAMPIER Thermoelectricity 87
Thermoelectric equations (single couple)
p2p
p pp p
p p
LI x
S Tc Th2TS 4 1
x S L( . )
By combining (1) and (4):
p p p pdT
I T S (1)dx
p2p
p pp p
p p
2p p p p
p pp p
2p p p p
p p pp p
LI x
S Tc Th2I T
S L
I L S Tc Thx 0 I Th
2 S L
I L S Tc Thx L I Tc
2 S L
2 nn
n nn n
n n
2n nn n
n nn n
2n pn n
n p nn n
LI x
S Tc Th2I T
S L
S Tc ThI Lx 0 I Th
2 S L
S Tc ThI Lx L I Tc
2 S L
If we sum and we get the power at the hot side of the system .
Similarly if we sum and we obtain the power at the cold side .
p x 0 n x 0 h
p x L p x L c
p
n
I
Thermal
x x+dx
L 0
Th Tc
Daniel CHAMPIER Thermoelectricity 88
Thermoelectric equations (single couple)
2
h
2
c
2elec
r II Th k Th Tc
2
r II Tc k Th Tc
2
W I Th Tc r I
With the electrical resistance of a pair of legs PN.
the overall heat transfer coefficient of a pair of legs PN.
the Seebeck coefficient of the thermocouple PN
p pn n
n p
LLr
S S
p pn n
n p
SSk
L L
p n
p
n
I
Thermal
x x+dx
L 0
Th Tc
2p p p pn n n n
p nhn p n p
2p p p pn n n n
c p nn p n p
2p nelec
L SL SII Th Tc Th
S S 2 L L
L SL SII Tc Tc Th
S S 2 L L
W I Th Tc r I
Simplified Thermoelectric Equations
for a single couple
Welec=h-c
Daniel CHAMPIER Thermoelectricity 89
Thermoelectric equations (modules)
Assuming that the cross sections of the legs are the same and considering the leg lengths equal we can write: n pS S n pL L
.
.
.
2
h
2
c
2elec
r IN I Th k Th Tc
2
r IN I Tc k Th Tc
2
W N I Th Tc r I
n p SK N
L
n p LR N
S
Simplified Thermoelectric Equations
for a module
N
Ceramic plate
(electric insulation)
P-Type
Semiconductor
Pellets
conducting strip N-Type
Semiconducto
r Pellets
N
P
N
P
The n-type and p-type thermoelements are electrically connected in serie by a conductor, and thermally in parallel.
The conductor is assumed to have negligible electrical resistance and thermal resistance.
p pn n
n p
LLr
S S
p pn n
n p
SSk
L L
p n
N number of couples (2N legs)
.
.
.
2
h
2
c
2elec
R IN I Th K Th Tc
2
R IN I Tc K Th Tc
2
W N I Th Tc R I
Metal
solders p n n n p p
RL : Load
I
Daniel CHAMPIER Thermoelectricity 90
Electrical model of TE module
.Voc N Th Tc
A load resistor RL is connected to the module
n p LR N
S
. . .oc
L L L
N Th TcV N TI
R R R R R R
N
Ceramic plate
(electric insulation)
P-Type
Semiconductor
Pellets
conducting strip N-Type
Semiconducto
r Pellets
N
P
N
P
Metal
solders p n n n p p
RL : Load
I
. 2elecW N I Th Tc R I
The module can be modeled as a voltage source Voc with internal resistance R
R
Voc
TC
TH
RL
TE module
Rheostat
VO
I
Daniel CHAMPIER Thermoelectricity 91
Maximizing power output from a generator
.Voc N Th Tc
n p LR N
S
. . .oc
L L L
N Th TcV N TI
R R R R R R
. . .2 2 2 2L
L 2L
RWelec R I N T
R R
By differentiating Welec with respect to RL we can find the value of load resistance that gives the maximum output power.
( ). .2 2 2L
3L L
R RWelecN T 0
R R R
Adapted load RL=R
. . . . . .. . . . . .
. pn
pn
2 2 2 2Max 2 2 2 2 2 2 2elec
n p n p
N T N S N S 2 N S N SW T T T T
2 R 8L 8L 8L4L
n pN LR
S
R
Voc
TC
TH
RL
TE module
Rheostat
VO
I
. 2pnelecW N I Th Tc R I Can also be written :
n ppn 2
pn
pn
p n
p n
21
we can find the the maximum output power.
!
Daniel CHAMPIER Thermoelectricity 92
Maximizing power output from a generator
.
. .pn
Max 2 2elec
N SW T
8L
Dependence upon the temperature
difference across the thermoelements
Construction :
number of thermoelements
cross-sectional area
length of each element.
‘‘power factor’’ :
type of TE material
The thermal conductivity, , does not appear and so does not directly impact the maximum power.
thermal resistances connecting the
thermocouples
to the thermal reservoirs
impacts T across
the thermoelement. TE
Generator
R
Voc
TC
TH
RL
TE module
Rheostat
VO
I
First conclusion : L as short as possible! Is it true ?
Daniel CHAMPIER Thermoelectricity 93
Maximizing power output from a generator
Metal
solders
n,p pellets
p n n n p p Thermal contact resistances
Electrical contact resistances
. .c c
1 1Voc N Th Tc N T
L L1 1
L L
. pnn p
L LR
2 SS
n p S
kL
Thermal contact resistance
R
Tc
Th
Rc
R c
T pellets
. .pellets
c cc
R 1 1T Th Tc Th Tc Th Tc
R LR 2 R 1 2 1R L
.n p pnL 2 LR N N
S SElectric contact resistance
Re
pn Lecc N
S
: Equivalent length
Lec: Equivalent length
int
. .c
oc
LL
1N T
L1
V LILecR R
R 1 RL
Electric internal resistance
int Re
LecR R 2x c R 1
L
You must take in account the thermal and electrical contact resistance
n ppn 2
Open circuit voltage
Current
pn4S.λ
cLθcRθ cLθ
Daniel CHAMPIER Thermoelectricity 94
Maximizing power output from a generator
Metal
solders
n,p pellets
p n n n p p Thermal contact resistance
Electrical contact resistance
. .c c
1 1Voc N Th Tc N T
L L1 1
L L
R
Tc
Th
Rc
R c
T pellets
int
. .oc
cecLL
V N T 1I
LLR R 1R 1 RLL
int
. . . . .. . .. . . . .
. . . . . pn
2 2 2 2 22 2 2pelletsMax 2 2
elec 2 2 2pnc ec c ec c
N T N S TN T 1 1 N S 1W T
4 R 4 R 8 L 8 LL L L L LL1 1 1 1 1 1
Lec L L L L L
.( . .) . )( c c
c
2ec
2 3ec
L 2 L L LF L0
L
L L
L L L L : , , 0max ( ) ( )c c c c2
ec ecc2
c1 1 1 1
L L L 8L L L L 8L L2 2 2 2
Manufacturing Factor
The maximum power for an adapted load can be evaluated again :
. .. . . . . .
.
pn pn
Max 2 2 2 2elec 2
ec c
N S 1 N SW T T F L
8 8L LL 1 1
L L
The maximum power can also be evaluated as a function of the length L :
Daniel CHAMPIER Thermoelectricity 95
Maximizing power output from a generator
Metal
solders
n,p pellets
p n n n p p Thermal contact resistance
Electrical contact resistance
R
Tc
Th
Rc
R c
T pellets
.. . .
pn
Max 2 2elec 2
ec c
N S 1W T
8L L L1 1
L L
red: Lec = 0 Lc = 0.
orange: Lec = 0.1 L c = 0.
green: Lec = 0 L c = 0.1
blue: Lec= 0.1 L c = 0.1
yellow: Lec= 0.1 L c = 0.5
There is an optimum for the leg’s length
= max ( )c c c2
ec1 1
L L L 8L L2 2
Manufacturing Factor
The manufacturing factor quantifies the quality of manufacture of
a device. This factor depends mainly on the thermal contacts.
θcmax LL 0Lec θC
pn
cθθ R.
2S.λ
LR 2If then and
Thermal impedance matching !
Daniel CHAMPIER Thermoelectricity 96
Maximizing Efficiency
The input energy is the heat energy entering the hot junction
.
2
pnHR I
N I Th K T2
The ouput energy is the electrical energy
. .
L
N TI
R R
. . .2 2 2 2L
L 2L
RR I N T
R RWelec
Efficiency
. .
.
2 2 2L2
L2
Hpn
RN T
R RWelec
R IN I Th K T
2
After some calculation and by defining LRm
R
.( )
.( ).H
2 2
mWelec T m 1
KR m 1 TTh 12Th m 1N Th
by defining
..
. . .
2 2 22 2
pn pn
Nz
K R 4
The efficiency becomes
.( )
.( )
mT m 1
m 1 TTh 1ZTh 2Th m 1
Carnot efficiency
Figure of merit
H
p n n n p p
RL : Load
I Welec
n p n p
Daniel CHAMPIER Thermoelectricity 97
Efficiency for different electrical loads
The efficiency
.( )
.( )H
mWelec T m 1
m 1 TTh 1ZTh 2Th m 1
The load must be adapted
0 1 2 3 4 5 6 7 8 9 100
0.01
0.02
0.03
0.04
0.05
0.06
0.07
m
eff
icie
ncy
Efficiency function of the load
Tc=20°
Th=170°C
zT=1
Exemple of efficiency
For ZT=1
Th=170°
T=150 °
There is a maximum for m1.4
Daniel CHAMPIER Thermoelectricity 98
Maximizing Efficiency
The efficiency
.( )
.( )H
mWelec T m 1
m 1 TTh 1ZTh 2Th m 1
m can be chosen to maximize the efficiency
( ) ..( )
2
2 2
T 2 2m 2zTh 2 Tz Th z
m Th 2zThm 2zTh 2m 4m 2 Tz
20 2m 2zTh 2 Tz 0m
( )opt
2zTh 2zTc 4 Th Tcm z 1
2 2
optm 1 zT
( )Th Tc
T2
.T 1 zT 1
TcTh 1 zTTh
.2 2
z
efficiency is a function of zT (Dimensionless figure of merit)
( )Th TcT
2
Where T is the average temperature
Daniel CHAMPIER Thermoelectricity 99
Maximum Efficiency
m can be chosen to maximize the efficiency optm 1 zT
.T 1 zT 1
TcTh 1 zTTh
where T is the average temperature
0 0.5 1 1.5 2 2.5 3 3.5 40
0.05
0.1
0.15
0.2
0.25
0.3
0.35
zT
eff
icie
ncy
efficiency versus ZT
Tc=20°C
Th=170°C
Carnot efficiency
TE efficiency
0 50 100 150 200 2500
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
Temperature diffence Th-Tc K
eff
icie
ncy
Efficiency function of temperature difference
ZT=1
ZT=1.5
Carnot efficiency
Tc=20°C
The efficiency becomes
Daniel CHAMPIER Thermoelectricity 100
Which values for the material properties ?
Assumptions for the calculations :
The material properties are temperature independent
, ρ, α as function of the temperature for Thermonamics Ingots
The equations remain valid if one chooses the value at the average temperature.
Th Tc
Tav2
= (Tav)
ρ=ρ(Tav)
α =α(Tav)
Daniel CHAMPIER Thermoelectricity 101
Finite Element Modeling
Finite Element Software Package : Comsol, Ansys , etc
Final COMSOL mesh FEA model of a thermoelement
junction in COMSOL
The voltage gradient is seen in color
the arrows indicate heat flow
Emil Jose Sandoz-Rosado, Thesis, Improved Modeling of a Thermoelectric Module
The analysis of dozens of thermoelements pairs is highly computationally intensive
The model is limited to a single pair
a FE model can provide several unique advantages. It can solve the governing set of partial differential equations that cannot be solved analytically.
It permits the investigation of complex geometries.
The non-linearities of the material property temperature-dependency can be handled, whereas an analytical solution does not exist.
Daniel CHAMPIER Thermoelectricity 102
Thermoelectric equations : other models
2
h
2
c
2elec
r II Th k Th Tc
2
r II Tc k Th Tc
2
W I Th Tc r I
Standard simplified model
2
h
2
c
2elec
r II Th k Th Tc
2
r II T
1Th Th Tc
2
1Tc Th Tc
2
Th Th T
c k Th Tc2
W c Tc I TI hr Tc
2
h
2
c
2elec
r II Th k Th Tc
2
r II Tc k
1Th Tc
Th Tc2
W I Th Tc
2
1Th Tc
r I
2
( )
Tm
TT
Th TcTm
2
Thomson simplified model
Thomson Seebeck simplified model
All parameter evaluated at
Seebeck’ surface coefficients
Introducing Thomson’ coefficient
1996 Chen The influence of Thomson effect on the maximum power output and maximum efficiency of a thermoelectric generator
Daniel CHAMPIER Thermoelectricity 103
Global generator You must take in account the heat exchangers, the wafers, the contact resistance etc.
Metal
solders
n,p
pellets p n n n p p
Exchanger
Exchanger
Ceramic wafer
Ceramic wafer
Ths Heat source : hot gas, hot liquid etc.
Heat sink : cold gas, cold liquid etc
Th
Tc
Tcs
Rc
Tcs
Ths
Tc
Th
Rh
Thermoelectric module Welec
h
c
Thermal resistance model of the generator
.
.
.
2
h
2
c
2elec
r IN I Th k Th Tc
2
r IN I Tc k Th Tc
2
W N I Th Tc r I
Thermoelectric equations
h c
h
c
Welec
Ths Th
Rh
Tc Tcs
Rc
Thermal equations
elec
2 2 2
elecelec
elec L
N. (Th Tc)I
R
N (Th Tc)W
R
with R N.R R
Electrical equations
Classical correlations are used to
determine heat transfer coefficients 1
contact ceramic metal HS CSR R R R Rh.A
Convective heat transfer Conductive heat transfer
Daniel CHAMPIER Thermoelectricity 104
Global generator
The objective is to determinate Tc and Th
.
.
.
2
h
2
c
2elec
r IN I Th k Th Tc
2
r IN I Tc k Th Tc
2
W N I Th Tc r I
Thermoelectric equations
h c
h
c
Welec
Ths Th
Rh
Tc Tcs
Rc
Thermal equations
2 2 2
elec
N. (Th Tc)I
Relec
N (Th Tc)W
Relec
Electrical equations
2
hr I Ths Th
N I Th k Th Tc2 Rh
.
N. (Th Tc)I
Relecby substituting
2 2 2
3 22
elec elec
N Th Tc Th r Th Tc Ths ThN Nk Th Tc 0
Rh2
( ) ( )
R .R
we get :
(1)
(6)
(3)
(1),(3)
3 2 2 2 3 2 22 2 3 2c c c
c2 2 2elec elecelec el
2h
ech
elec
N r T N T N r TN 1 N r 1 1 ThsN k NK T 0
R 2 Rh R 2 RhR RT
RT
. . .- . - - .
by collecting Th :
(2)
(4)
Doing the same with (2),(4) we get :
. . .. . .
3 2 2 2 2 23 2 3 22c c c
c c2 2 2elec elecelec elec elec
2h h
N r T N T N T1 N r Thc 1 N r TcNk NK T T 0
2 R Rc 2 R RcR R RT T
(5)
Daniel CHAMPIER Thermoelectricity 105
Global generator
The determination of Tc and Th, gives the electrical Power
(5)
3 2 2 2 3 2 22 2 3 2c c c
c2 2 2elec elecelec el
2h
ech
elec
N r T N T N r TN 1 N r 1 1 ThsN k NK T 0
R 2 Rh R 2 RhR RT
RT
. . .- . - - .
We must add the constraints
. . .. . .
3 2 2 2 2 23 2 3 22c c c
c c2 2 2elec elecelec elec elec
2h h
N r T N T N T1 N r Thc 1 N r TcNk NK T T 0
2 R Rc 2 R RcR R RT T
(6)
We obtain a system of two quadratic equations with two unknowns
hTThs Tcs
For each equation there is only one solution that comply the constraint.
Each solution is a function of Tc.
The intersection of the two solutions gives the couple of value of Tc and Th.
TcThs Tcs
The problem is complex but can be solved with Newton-type methods
Daniel CHAMPIER Thermoelectricity 106
Examples of commercial modules
HiZ
Thermonamic
Komatsu
Daniel CHAMPIER Thermoelectricity 107
M a n u f a c t u r e r s
Although a fast rise in commercial applications of TE modules is observed , only few
tens of manufacturers operate in the world market.
Among the manufacturers and suppliers, we can mention the very strong positions of
a few wellknown American companies (HiZ , Melcor and Marlow,for example) who
have been in the market for many years and have maintained leading positions.
Another group consists of the Commonwealth of Independent States (CIS)
companies – mainly Russian and Ukrainian. Most of them are young and started only
a decade ago but are based on a high TE technology level and scientific basis from
the former CIS’s (Commonwealth of Independent States) TE scientific school. Most of
the companies are experienced in high-performance modules. Very difficult to get
information from ALTEC Термоэлектрическая компания !!!!!
Chinese companies are also relatively young. They have demonstrated a fast
expansion in the TE market and dominate in low-cost types. Thermonamic
Production of TE modules is also developing rapidly in Japan and Europe (Komatsu
Eureka).
a report by G Gromov
Daniel CHAMPIER Thermoelectricity 108
Example of TE module HiZ 14
• 49 thermocouples
• "Hot Pressed", Bismuth Telluride based high
strength capable of enduring rugged applications
(up to 10 years or longer).
• The bonded metal conductors enable the HZ-14
module to operate continuously at temperatures
as high as 250°C and intermittently as high as
400°C without degrading the module.
www.hi-z.com
For most applications, insulating ceramic wafers must be placed on both sides of the
module
Daniel CHAMPIER Thermoelectricity 109
Example of TE module HiZ 14
Physical Properties Value Tolerance
Width & Length 6.27 cm 0.01 (0.25)
Thickness
(Special Order) 0.508
0.01 (0.25)
0.002 (0.05)
Weight 82 grams 3 grams
Compressive Yield Stress 10 ksi (70 MPa) minimum
Number of active couples 49 couples ----
Thermal Properties
Design Hot Side Temperature 230 C 10 (20)
Design Cold Side Temperature 30 C 5 (10)
Maximum Continuous Temperature 250 C ----
Minimum Continuous Temperature none ----
Maximum Intermittent Temperature 400 C ----
Thermal Conductivity 2.4 W/m*K +0.001
Heat Flux 9.54 W/sqcm 0.5
Electrical Properties (as a generator)*
Power 13 Watts minimum
Load Voltage 1.65 Volts 0.1
Internal Resistance 0.15 Ohm 0.05
Current 8 Amps 1
Open Circuit Voltage 3.5 Volts 0.3
Efficiency 4.5 % minimum www.hi-z.com
Daniel CHAMPIER Thermoelectricity 110
Example of TE module HiZ 14
R
Voc
TC
TH
RL
TE module
Rheostat
VO
Electrical Power
0
2
4
6
8
10
12
14
16
0 0,5 1 1,5 2 2,5 3
Po
we
r W
Load ohm
Power versus load
Thot=250°C
Thot=200°C
Thot=150°C
Thot=100°C
Tcold =50°C
www.hi-z.com
Optimal load (adapted)
Daniel CHAMPIER Thermoelectricity 111
Example of TE module HiZ 14
R
Voc
TC
TH
RL
TE module
Rheostat
VO
Electrical Power
www.hi-z.com
0
2
4
6
8
10
12
14
16
0 0,5 1 1,5 2 2,5 3 3,5
Po
we
r W
Voltage Vo (V)
Power versus voltage
Thot=250°C
Thot=200°C
Thot=150°C
Thot=100°C
Tcold =50°C
Voc/2 Voc
Maximum power
Open circuit voltage
and
adapted voltage
Daniel CHAMPIER Thermoelectricity 112
Example of TE module HiZ 14
R
Voc
TC
TH
RL
TE module
Rheostat
VO
I
Electrical Power
www.hi-z.com
0
2
4
6
8
10
12
14
16
0 2 4 6 8 10 12 14 16 18
Po
we
r W
Current (A)
Power versus current
Thot=250°C
Thot=200°C
Thot=150°C
Thot=100°C
Tcold =50°C
Daniel CHAMPIER Thermoelectricity 113
Thermonamic TEHP1-12656-0.3 Bi-Te
The module can work at the temperature of as high as 330°C heat source continuously and up to 400°C intermittently.
The module is stuck with the high thermal conductivity graphite sheet on its both sides of the ceramic plates to provide low
contact thermal resistance
Daniel CHAMPIER Thermoelectricity 114
KOMATSU
[Technical Features]
1. World's top conversion efficiency. Ability to generate a large output even
with a relatively small difference in temperature. (Functional conditions: 280°C
in the high-temperature side and 30°C in the low-temperature side)
2. High output power density at approximately 1W/cm2. Use in compact
equipment.
3. Simplified handling of circuits thanks to the low current of 3A and high
voltage of 8V at the maximum output.
[Specifications]
Size : 50mm x 50mm x 4.2mm (excluding the lead wire)
Weight : 47g
Output : Max. 24W
(when 280°C in the high-temperature side and 30°C in the low-temperature
side)
Temperature range for use : 280°C (max.) and 250°C or lower (normal) in the
high-temperature side and 150°C (max.) in the low-temperature side
Conversion efficiency : Max. 7.2%
Raw material : BiTe family
[Prices ]
283 €
Daniel CHAMPIER Thermoelectricity 115
Comparison and prices Producer P/N
Open Voltage
[V]
Internal resistance
[Ω] Power [W] Size[mm]
Price per
module
€ $
Design temperature: Hot side 300 ℃ and cold side 30 ℃. Material : Bi2 Te3 Max. Temp. 380°C
TH
ER
MO
NA
MIC
TEP1-1263-3.4 10,7 5,4 5,2 30x30 28 40
TEP1-1264-1.5 7,8 3 5,1 40x40 28 40
TEP1-12656-0.8 9,5 1,8 13 56x56 63 90
TEP1-12656-0.6 8,4 1,2 14,6 56x56 63 90
TEHP1-12635-1.2 9 2,7 7,5 35x35 28 40
TEHP1-1264-0.8 7,2 1,8 7,1 40x40 63 90
TEHP1-12656-0.3 7,8 0,8 19,2 56x56 63 90
Design temperature: Hot side 230 °C and cold side 30 °C Material: Bi2 Te3 Max. Temp. 250 °C
HI-
Z
TE
CH
NO
L
OG
Y
HZ-2 6,53 4 2,5 29x29 49 69
HZ-9 6,5 1,15 9 62,7x62,7 106 149
HZ-14 3,5 0,15 13 62,7x62,7 98 139
HZ-20 5 0,3 19 75x75 147 209
Design temperature: ΔT=200 °C Material: Bi2 Te3 Max. Temp. 200 °C
EU
RE
CA
Messte
ch
nik
Gm
bH
TEG1-9.1-9.9-0.8/200 5,4 9 0,8 9,1x9,9 76 108
TEG1-30-30-8.5/200 10,8 3,4 8,5 30x30 38 54
TEG1-40-40-19/200 10,8 1,5 19 40x40 56 80
TEG2-40-40-19/200 1 10,6 1,5 19 40x40 37 52
TEG2-50-50-40/200 10,3 0,7 40 50x50 67 95
Design temperature: ΔT=170 °C Material ; Bi2 Te3 Max. Temp. 250 °C
Ma
rlo
w
inc
.
TG 12-4-01L 9,45 6,83 4,05 29,97x34,04 19 28
TG 12-6-01L 9,51 4,56 6,16 40,13x44,70 29 42
TG 12-8-01L 9,43 3,46 7,95 40,13x44,70 36 52
TG 12-2.5-01L 9,56 10,47 2,71 29,97x34,04 31 45
Design temperature: ΔT=200 °C Material : Bi2 Te3 Max. Temp. 250 °C
Cristal Ltd. Type G-127-14-16-L-S ? 2 2,42 40x40 67 40
Design temperature: Hot side 190 °C and cold side 65 °C Material Bi2 Te3 Max. Temp. 200 °C
Watronix INBC1-127.08 HTS not specified not specified 8,5 40x40 20 29
[1] Chinese production: related load output to TEG1-40-40-19/200 but shorter lifetime and higher tolerances, certainly cheaper )
With the exchange rate from 04.04.11: 1 Euro = 1,4179 US-Dollar
Daniel CHAMPIER Thermoelectricity 116
Power convertor
DC DC
Converter
The temperature Th and Tc varies a lot.
An electric DC-DC
regulator is necessary
output voltage of the TE
modules fluctuates a lot.
TE modules
Voc=N. (Th-Tc)
R=R(Th,Tc) VTE
ITE
Voc
R
TE Generator
The loads need regulated voltage
Daniel CHAMPIER Thermoelectricity 117
Power convertors for TE generators
Power convertors convert electric power from one form to
another
DC – DC
Step-up (Boost) : The storage voltage is higher than the Te modules voltage
Bust-Book : The storage voltage is higher or lower than the Te modules voltage
TE modules are direct current (DC) source
Loads are mostly DC (batteries ) but possibly alternating current AC (grid connection)
DC – AC
Inverter commonly used to supply AC power from DC sources such as solar panels or batteries
Daniel CHAMPIER Thermoelectricity 118
Boost convertor
Vin
Iin
Pulse width
Modulation
Vout
Iout
Voc
R
TE Generator DC/DC convertor Battery + Load
Virtual load
Dc duty cycle : fraction of the commutation period T during which the switch is On.
2T
Vin
Vout
Vin-Vout
VL
Inductance voltage
Inductance current=Iin
DcxT 2T
Switch state
Vin
Vout
Vin-Vout
ILmax
ILmin
VL
IL
Inductance voltage
Inductance current=Iin
DcxT
Switch state
on on on off off
time
time
time
on off on off
ILmax
ILmin
T T
Average Iin
Vin
Iin = IL
Vout
Iout
Voc
R
SWITCH ON
VL
Vin
Iin = IL
Vout
Iout
Voc
R
SWITCH OFF
VL
Daniel CHAMPIER Thermoelectricity 119
Boost convertor
Vin
Iin
Pulse width
Modulation
Vout
Iout
Voc
R
TE Generator DC/DC convertor Battery + Load
Virtual load
(1 )in outV V Dc
(1 )
outin
II
Dc
Ideal convertor :
outV is fixed by the battery voltage
The choice of the duty cycle therefore imposes the voltage Vin
and thus the currents
For an adapted load (maximum power) Vin must be equal to Voc/2
in in in out out outP V I V I P
oc inin
V VI
R
Voc of the TE modules fluctuates a lot.
The duty cycle needs to
follow these variations
Daniel CHAMPIER Thermoelectricity 120
Maximum Power Point (MPP)
R
Voc
TC
TH
Rv
TE module
Virtual Load
Vin
Iin
Electrical Power
0
2
4
6
8
10
12
14
16
0 0,5 1 1,5 2 2,5 3 3,5
Po
we
r W
Voltage Vo (V)
Power versus voltage
Thot=250°C
Thot=200°C
Thot=150°C
Thot=100°C
Tcold =50°C
Voc/2 Voc
Maximum power point
Open circuit voltage
and
adapted voltage
Exemple of TE module HiZ 14
Open circuit voltage
and
adapted voltage
Voltage Vin (V)
The MMP changes with the temperatures
Intelligence is necessary
Daniel CHAMPIER Thermoelectricity 121
Boost convertor with MPPT
Vin
Iin
Pulse width
Modulation
microcontrollor
Vout
Iout
Voc
R
TE Generator DC/DC convertor Battery + Load
Virtual load
The solution is to control the DC/DC converter with a Maximum Power Point Tracker
Measure Iin
Measure Vin
Calculate Pin
Change duty cycle
Compare with
previous Pin
Vin and Iin change
Question : how to change the duty cycle?
Daniel CHAMPIER Thermoelectricity 122
Boost convertor with MPPT
Measure Vin,Iin
Go to the max
Change Dc
Calculate ΔV, ΔP
Example of algorithm “Perturb and Observe”
power transferred to the load
Daniel CHAMPIER Thermoelectricity 123
Temperature measurements
Daniel CHAMPIER Thermoelectricity 124
Temperature
The temperature is a particular quantity
We can define equality but we can not define the sum of two
temperatures
10kg+5kg=15kg
10° + 20° = ?
Common unit:
degree Celsius, symbol ° C
0 ° C Freezing, 100 ° C boiling water
absolute temperatures:
The kelvin, symbol K
Triple point of water is 273.16 K
Matching :
t (°C)+To= T(K) with To= 273,15 K.
Daniel CHAMPIER Thermoelectricity 125
ITS (International Temperature Scale) T90
17 reference points of temperature
Substance and its state Defining point T90 K T90 °C
Triple point of hydrogen 13.8033 -259.3467
Triple point of neon 24.5561 -248.5939
Triple point of oxygen 54.3584 -218.7916
Triple point of argon 83.8058 -189.3442
Triple point of mercury 234.3156 -38.8344
Triple point of water 273.16 0.01
Melting point of gallium 302.9146 29.7646
Freezing point of indium 429.7485 156.5985
Freezing point of tin 505.078 231.928
Freezing point of zinc 692.677 419.527
Freezing point of aluminum 933.473 660.323
Freezing point of silver 1234.93 961.78
Freezing point of gold 1337.33 1064.18
Freezing point of copper 1357.77 1084.62
Daniel CHAMPIER Thermoelectricity 126
Thermocouples
VAB is function of:
- Nature of the two
metals
- Temperatures T1 and
T2
It consists of two dissimilar metals, joined together.
When the junction of the two metals is heated or cooled a voltage is produced
that can be correlated back to the temperature.
Thermocouple : a sensor for measuring temperature
T1 sensor junction
T2 reference junction
Table for T2 = 0 and couple A,B EAB(T1)
Daniel CHAMPIER Thermoelectricity 127
Thermocouples Type K
http://srdata.nist.gov/its90/main/
Table ITS-90 Thermoelectric Voltage in mV
°C 0 -1 -2 -3 -4 -5 -6 -7 -8 -9 -10
-20 -0.778 -0.816 -0.854 -0.892 -0.930 -0.968 -1.006 -1.043 -1.081 -1.119 -1.156
-10 -0.392 -0.431 -0.470 -0.508 -0.547 -0.586 -0.624 -0.663 -0.701 -0.739 -0.778
0 0.000 -0.039 -0.079 -0.118 -0.157 -0.197 -0.236 -0.275 -0.314 -0.353 -0.392
0 0.000 0.039 0.079 0.119 0.158 0.198 0.238 0.277 0.317 0.357 0.397
10 0.397 0.437 0.477 0.517 0.557 0.597 0.637 0.677 0.718 0.758 0.798
20 0.798 0.838 0.879 0.919 0.960 1.000 1.041 1.081 1.122 1.163 1.203
30 1.203 1.244 1.285 1.326 1.366 1.407 1.448 1.489 1.530 1.571 1.612
40 1.612 1.653 1.694 1.735 1.776 1.817 1.858 1.899 1.941 1.982 2.023
50 2.023 2.064 2.106 2.147 2.188 2.230 2.271 2.312 2.354 2.395 2.436
60 2.436 2.478 2.519 2.561 2.602 2.644 2.685 2.727 2.768 2.810 2.851
70 2.851 2.893 2.934 2.976 3.017 3.059 3.100 3.142 3.184 3.225 3.267
80 3.267 3.308 3.350 3.391 3.433 3.474 3.516 3.557 3.599 3.640 3.682
90 3.682 3.723 3.765 3.806 3.848 3.889 3.931 3.972 4.013 4.055 4.096
100 4.096 4.138 4.179 4.220 4.262 4.303 4.344 4.385 4.427 4.468 4.509
110 4.509 4.550 4.591 4.633 4.674 4.715 4.756 4.797 4.838 4.879 4.920
Daniel CHAMPIER Thermoelectricity 128
Thermocouples Type K
Coefficients of reference equations giving the thermoelectric voltage, E, as a function of
temperature, t90 , for the indicated temperature ranges
Temperature below 0°C E = sum(i = 0 à n) ci*t90i t90 = Temperature (°C) E = Voltage (mV)
Temperature above 0 °C E = sum(i = 0 à n) ci*t90i + a0*e
a1(t
90-a
2)2
Température (°C) -270 à 0 0 à 1372
c0 0 -0.176004136860e-1
c1 0.394501280250e-1 0.389212049750e-1
c2 0.236223735980e-4 0.185587700320e-4
c3 -0.328589067840e-6 -0.994575928740e-7
c4 -0.499048287770e-8 0.318409457190e-9
c5 -0.675090591730e-10 -0.560728448890e-12
c6 -0.574103274280e-12 0.560750590590e-15
c7 -0.310888728940e-14 -0.320207200030e-18
c8 -0.104516093650e-16 0.971511471520e-22
c9 -0.198892668780e-19 -0.121047212750e-25
c10 -0.163226974860e-22
a0 0.1185976
a1 -0.1183432e-3
a2 0.1269686e+3
Daniel CHAMPIER Thermoelectricity 129
Thermocouples Type K
coefficients of approximate inverse functions giving temperature, t90 , as a function of the
thermoelectric voltage, E, in selected temperature and voltage ranges.
T90 = c0 + c1E + c2E2 + c3E
3 + c4E4 + ... + cnEn
Température (°C) -200 à 0 0 à 500 500 à 1372
Tension (mV) -5.891 à 0.000 0.000 à 20.644 20.644 à 54.886
c0 0 0 -1.318058E+02
c1 2.5173462E+01 2.508355E+01 4.830222E+01
c2 -1.1662878E+00 7.860106E-02 -1.646031E+00
c3 -1.0833638E+00 -2.503131E-01 5.464731E-02
c4 -8.9773540E-01 8.315270E-02 -9.650715E-04
c5 -3.7342377E-01 -1.228034E-02 8.802193E-06
c6 -8.6632643E-02 9.804036E-04 -3.110810E-08
c7 -1.0450598E-02 -4.413030E-05 0
c8 -5.1920577E-04 1.057734E-06 0
c9 0 -1.052755E-08 0
Erreur (°C) -0.02 à 0.04 -0.05 à 0.04 -0.05 à 0.06
Daniel CHAMPIER Thermoelectricity 130
Thermocouples
Standard IEC 584.1 (1995) IEC - International Electrotechnical Commission
Letter-designation for
Thermocouples. Alloy
Domaine de la table en
C
K Nickel-chromium alloy(+)/Nickel-aluminium alloy(-) -270 to 1370 C
T Copper(+)/Copper-nickel alloy(-) -270 to 400 C
J Iron(+)/Copper-nickel alloy(-) -210 to 1200 C
N Nickel-chromium-silicon alloy(+)/Nickel-silicon alloy(-) -270 to 1300 C
E Nickel-chromium alloy(+)/Copper-nickel alloy(-) -270 to 1000 C
R Platinum13%Rhodium(+)/Platinum(-) -50 to 1760 C
S Platinum10%Rhodium(+)/Platinum(-) -50 to 1760 C
B Platinum30%Rhodium(+)/Platinum6%Rhodium(-) 0 to 1820 C
G (Not Official Symbol or Standard) Tungsten / Tungsten 26% Rhenium 1000 to 2300 C
C (Not Official Symbol or Standard) Tungsten 5% Rhenium / Tungsten 26% Rhenium 0 to 2300 C
D (Not Official Symbol or Standard) Tungsten 3% Rhenium / Tungsten 25% Rhenium 0 to 2400 C
Daniel CHAMPIER Thermoelectricity 131
International Standard
• IEC 60584-1 Thermocouple reference tables - E = f(T) e.m.f.-temperature relationships
• IEC 60584-2 Tolerances
– This standard contains the manufacturing tolerances for both noble and base metal
thermocouples manufactured in accordance with e.m.f.-temperature relationships of Part
1 of the standard.
• IEC 60584-3
Thermocouples - : Extension and compensating cables - Tolerances and identification system
Daniel CHAMPIER Thermoelectricity 132
Thermocouples : specifications
Daniel CHAMPIER Thermoelectricity 133
Thermocouples : Cold junction
compensation
E(T1)=VAB + E(T2)
Thermocouples measure the temperature difference between two points,
not absolute temperature
Daniel CHAMPIER Thermoelectricity 134
industrial thermocouples
VAB
B
A
T1= sensor temperature
Cu
T2= reference temperature
voltmeter
Daniel CHAMPIER Thermoelectricity 135
Thermocouples :
Extension Wire
VAB
B
A
T1= 1100°C Cu
T2= 25°C
Voltmeter
Ti= 100°C
Thermocouple grade
wire is wire that is
used to make the
sensing point (or
probe part) of the
thermocouple.
Extension grade wire is only used
to extend a thermocouple signal
from a probe back to the
instrument reading the signal.
The extension grade wire (or
sheath) typically will have a lower
ambient temperature limit in which
the wire may be used
Expensive
Cheap
Daniel CHAMPIER Thermoelectricity 136
Thermocouples :
sensitivity
Measurement system with high resolution and
quality
Sensors are very sensitive to electric noises
Thermocouple Type
Seebeck
Coefficient at 25 °C
(µV/°C)
Sensitivity for 0.1°C
(µV)
E 61 6.1
J 52 5.2
K 40 4.0
R 6 0.6
S 6 0.6
T 41 4.1
Daniel CHAMPIER Thermoelectricity 137
Thermocouples :
Properties
Advantages
Large measuring range
robust
Many forms
Response time
Cost
Disadvantages
Decalibration (oxidation ...)
Sensitivity to electrical noise
Daniel CHAMPIER Thermoelectricity 138
Thermoelectric cooler TEC
Daniel CHAMPIER Thermoelectricity 139
thermoelectric cooling and heating
By applying a low voltage DC power to a TE module, heat will be moved through the module from
one side to the other.
One module face, therefore, will be cooled while the opposite face is simultaneously heated.
It is important to note that this phenomenon may be reversed whereby a change in the polarity
(plus and minus) of the applied DC voltage will cause heat to be moved in the opposite direction.
Consequently, a thermoelectric module may be used for both heating and cooling thereby making it
highly suitable for precise temperature control applications
max
Tc1 zTQc Tc ThCOP
We T 1 zT 1Coefficient of performance
21 TcTh Tc ZTc ZT
2 2Maximum temperature difference
Daniel CHAMPIER Thermoelectricity 140
thermoelectric cooling and heating
http://www.ferrotec.com
Thermoelectric modules offer many advantages including:
− No moving parts
− Small and lightweight
− Maintenance-free
− Acoustically silent and electrically “quiet”
− Heating and cooling with the same module (including temperature cycling)
− Wide operating temperature range
− Highly precise temperature control (to within 0.1°C)
− Operation in any orientation, zero gravity and high G- levels
− Cooling to very low temperatures (-80°C)
advantages
drawbacks
− fall of COP when the temperature difference increases
− high dependence to room temperature
Daniel CHAMPIER Thermoelectricity 141
thermoelectric cooling and heating
Although thermoelectric (TE) phenomena was discovered more than
150 years ago, thermoelectric devices (TE coolers) have only been
applied commercially during recent decades.
For some time, commercial TECs have been developing in parallel
with two mainstream directions of technical progress :
• electronics and photonics, particularly optoelectronics and laser
techniques
• low power cooling (<500W)
Daniel CHAMPIER Thermoelectricity 142
Thermoelectric optoelectronics applications
http://www.tec-microsystems.com
Application of TE solutions :
optoelectronic devices such as diode lasers,
superluminescent diodes (SLD), various photodetectors,
diode pumped solid state lasers (DPSS), charge-coupled
devices (CCDs).
commercially during recent decades
TEC sub-assemblies provide a temperature-controllable,
uniform-temperature, high-emissivity surface used in
calibrating infrared (IR) detector arrays and FLIR systems.
(Infrared Cameras & Thermal Imagers )
Infrared Cameras
Miniature Thermoelectric Coolers for Telecom Applications
Daniel CHAMPIER Thermoelectricity 143
Thermoelectric optoelectronics applications
2012 Prospects for improvement in LED performance using thermoelectrics V. Semenyuk and R. Dekhtiaruk
Temperature is a key factor for LED performance
Lifetime, brightness and color stability are greatly
dependent on operation temperature
LED Coolers
Thermoelectrically cooled LED. by courtesy of Thermion Company
20 to 30ºC decrease of junction
temperature
Daniel CHAMPIER Thermoelectricity 144
Low power cooling (<500W)
TE Technology AC-027
Air Coolers 1) Select ambiant
2) Select system temperature
3) Read the heat the system can removed
desired system temperature : -10°C
Heat removed : 5 W
12V 4,6 A Fans 0.8A Pe=65W
If more heat to be removed, the desired temperature
could not be reach
desired system temperature : 25°C
Heat removed : 24 W
12V 4,6 A Fans 0.8A Pe=65W
COP = 0.08
COP = 0.37
Exemple : ambiant 25°C
Daniel CHAMPIER Thermoelectricity 145
thermoelectric cooler
Aside from a small fan, this electronic fridge has no
moving parts to wear out or break down. It’s not
affected by tilting, jarring or vibration (situations that
cause home fridges to fail). The governing module, no
bigger than a matchbook, actually delivers the cooling
power of a 10 pound block of ice.
The fridge can become a food warmer for a casserole,
burger or baby’s bottle only with the switch !
koolatron
Koolatron 12 Volt Coolers and Warmers
will heat or cool your lunch and beverages.
Daniel CHAMPIER Thermoelectricity 146
thermoelectric cooler
A Solid State thermoelectric module acts as a heat pump to
remove heat away from the fridge, utilizing state of the art,
unique heat pipe technology for improved performance.
Heat from the thermoelectric module is absorbed by the heat
pipe, vaporizing the liquid refrigerant and rapidly moving heat
away from the source, allowing for faster temperature drop. Uses
environmentally friendly R134A refrigerant.
This technology has been widely used by the Military, Aerospace
and Computer industries primarily for rapid heat transfer.!
koolatron
Daniel CHAMPIER Thermoelectricity 147
Vehicles cooling and heating
Ford group :
Thermoelectric HVAC (Heating,
Ventilation and Air-Conditioning)
Cool localy driver and passenger and
not the whole car