Transcript P10462 – Thermoelectric Power System for Improved Haitian

Young Jo Fontaine – ME
Dan Higgins – EE
Shawn Hoskins – ME
Luke Poandl – EE
Dan Scannell - ME
Provide power for cookstove using thermoelectric
generator (TEG)
 Market: Rural Haitians

High-level Customer Needs/Engineering Specs
 Low cost
• Ideal: <$10
• Marginal: <$50

TEG provides power
• Powers fan
• Recharges batteries
• Provides auxiliary power (i.e. cellphone charging)

System is intuitive
• Target customer can learn to use easily
THERMAL
BRIDGE
STOVE
AUXILIARY POWER
TEG
BATTERY
BUCK-BOOST
CONVERTER
FAN
Air flow from bottom
Air has duct flows into bottom
Flows around chamber
Through holes into chamber
Air flow into side
Flow uses Heat sink as duct
Flows around chamber
Through holes into chamber
18
16
14
12
10
Current
Design
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7
0
Calculated pressure drop from different systems
Only slightly more pressure drop from side flow design
Extra pressure drop due to losses through heatsink
Side flow design is acceptable for use
Design to provide heat from
heat pipe to hot side of TE
Used Iterative design
process
Cut away extra material to
keep heat transfer rate lower
Mounts to heat sink with
screws
Heat pipe is screwed into
center hole
Due to P3 Time constraint heat sink
had to be made in house
Used smallest and longest end mill
Iterative process, heat sink didn’t
provide enough cooling
Scallop design used to increase
surface area
Fan mounts inside Heat sink
serving double purpose
Heat sink mounted to stove with
custom L brackets
Fan mounted to Heat sink with L
brackets
 Primary
Needs
• Run Fan (includes start up)
• Provide Auxiliary Power
 Composed
of:
• TEG
• Converters
• Batteries / Battery Charger
• Fan
 Taihuaxing
TEP1-1264-1.5
• 5.9We
-
• 140Wth
40mm
+
40mm
Taihuaxing TEG Temperature Curves
3
2.5
DT=50
DT=60
Short Circuit Curent - Isc (A)
DT=80
DT=100
2
DT=110
DT=120
DT=130
1.5
DT=140
DT=150
DT=160
1
DT=170
Load Connected
Pmax
0.5
Linear (Pmax)
y = 0.3567x + 0.1154
R² = 0.9989
0
0
1
2
3
4
5
Open Circuit Voltage - Voc (V)
6
7
8
 Fan
• Runs @3.3VDC, 0.5W
• Stock Unit from Camp Stove
 DC-DC
Converters
• 5V & 3.3V Buck Boost
• Operate on 1.8-5.5Vin
• Switch up to 1.8A
 Future
Implementation
 Sample Open Circuit Voltage
• Determine Operating point of TEG
• Switch loads according to Voc
 Components
• Comparators
• Accumulation Clock
• Latching MOSFET’s
• D-Flip Flops
 Prototype construction is complete
• Modifications to design were made as necessary
 Thermal system provides close to target
temperature difference
• Provides about 145-150°C; target was 150-160°C
 TEG/electrical
system does not provide
expected power output
• Buck-boost converter may have failed
 Testing
will continue to attempt to get
system working as intended
 Initially, electrical
and mechanical
systems were tested separately
 Changes were made as seen fit
 Two systems were then integrated for full
system testing
 More modifications were made based on
results
 Mechanical
Materials Cost: $85.84
 Electrical Materials Cost: $143.78
 TEG Cost: $101.50
 Total
Prototype Cost: $331.12
 Under
mass production scale: $37.44
 Fan/duct
provide proper airflow to
combustion chamber
 Mass production cost is estimated to be
below marginal specification ($50)
 System operation is controlled with
simple toggle switch
• Must switch between battery and TEG power
 No
hazardous materials were used in
construction
 Electrical
system does not provide power
required
 Not all materials are readily available in
Haiti
 Unable to test lifetime of system
 System is currently not integrated with
P10461 stove
SUCCESSES


Fan and heat sink/duct
design provides proper
airflow for combustion
TEG has previously been
able to power the fan and
provide some auxiliary
power
FAILURES



TEG/electrical system does
not provide enough power
for all requirements
Ideal temperature
difference is not achieved
System not currently
integrated with prototype
stove
 Investigate
contact resistance of TEG
 Attempt to build system out of more
readily available materials
 Convert system for use with P10461 stove
 Sufficient heat sink design (in progress)
 Implement autonomous controlled
switching system