PowerStove:
Cooking for a Third of the World
MULTIDISCIPLINARY SENIOR DESIGN
PROJECTS P12441 & P12442
2011-2012
Motivation
 Two and half billion people depend on biomass (wood,
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dung, or agriculture residues) primarily for cooking
The practice of cooking with biomass has decimated many
ecosystems
Biomass use requires an enormous amount of human effort
to gather and process
Cooking with biomass creates considerable health problems
that continue to plague the world’s poorest populations
Cookstove emissions is the second-largest global source of
greenhouse gases after fossil-fuel combustion
2011-2012 Stove Project Scope
 To minimize the harmful effects associated with
cooking, two Rochester Institute of Technology (RIT)
multidisciplinary student engineering teams in
partnership with a NGO will design, build, and test a
more efficient, cleaner, and socially acceptable cook
stove using thermoelectrics and a simple blower.
The project will result in a minimum of two working
stoves that will be field tested during the summer of
2012.
Project Initial Target Customer
Borgne, Haiti
 Poorest country in Western
hemisphere ($420/person-year)
 75% of all energy consumed is
biomass
 Only 4% forested land left, huge
deforestation problems.
 H.O.P.E (Haiti Outreach - Pwoje
Espwa) partner NGO
RIT Advanced Cookstove Project Goals
This project will build on recent stove advancements to develop an improved stove
for Haiti and other developing nations with the goals of:
 reducing fuel use by a factor of two or greater in order to turn the tide on
deforestation and diminish the time and limited financial resources spent on
cooking;
 creating microenterprises for assembling the advanced stoves to generate
wealth and develop local expertise for maintaining the stoves in order to
improve chances of sustained stove adoption;
 enhancing conventional cooking techniques of traditional foods;
 provide an electrical power source to operate auxiliary loads such as radio,
lighting, charge cell phone batteries, and small UV water treatment
technologies; and
 improve the air quality to reduce the alarming rate of respiratory deaths
associated with cooking while combating global climate change.
Past Projects
 P10451 & 11451 – Developed
testing setup and process for
quantifying stove efficiencies
and emissions. Benchmarked
Haitian stove.
 P10461, 11461, & 11462 –
Developed first generation of
vendor and institutional cook
stoves using thermoelectrics and
blower.
Project 12442
Next Generation Charcoal Cook Stove for Haiti
 Build on the work done by project P11461 &11462 to
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develop an improved cookstove for vendors and
institutional users.
The improved cook stove should substantially reduce (by
more than 50%) the emissions and fuel needed for
cooking compared to the traditional stoves currently
used in Haiti.
Combine efficient cook stove and thermoelectric thermal
system.
The stove developed by team P11461 was designed to use
force draft to improve combustion and heat transfer to
the pot. The stove design also made use of recycled
material, attempted to reduce thermal losses by the use
of radiant barriers, and increase heat transfer to pot by
the use of a skirt.
Some modeling and experimentation was done, but not
comprehensive.
Project 12442
Preliminary Needs
Affordable (initial cost <$10 at high production quantities of 1000+)
 Cheaper to operate than current stove (less fuel for same cooking tasks)
 Significantly cleaner than current stove (reduced CO and PM emissions)
 Easy to operate (require little user interaction and simple and intuitive processes, require the same or
less effort than current practices for starting and cooking with stove.)
 Same or improved cooking controls (control cooking conditions for traditional Haitian cooking
practices). Obtain rapid boil quickly and then bring to simmer.
 Be able to be fabricated and assembled using Haitian artisan practices
 Transportable so that a single adult can move the stove 500 meters unassisted.
 Rugged, can handle being dropped by user multiple times, withstand harsh conditions such as rain and
high temperatures.
 Durable, should operate for five or more years with a use rate of at least twice a day or have simple,
cheap, and easily replaceable parts. Thermoelectric module will not fail due to high temperature and
gradients.
 Safe to operate, operator should not be injured during normal use and transport of the cook stove.
Internal needs:
 Maintain appropriate temperature gradient across thermoelectric module
 Achieve desired temperature gradient quickly
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Project 12442
Preliminary Specifications
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Production cost: <$10 for materials at 1-10K quantities, less than 3 hours of a Haitian’s craftsman labor
per stove.
Fuel use: 50% of traditional Haitian rebar fuel use for both Full Water Boil Test (WBT) and established
Controlled Cooking Test (CCT).
CO emissions: 25% of tradition Haitian rebar stove emissions for both WBT and CCT
PM emissions: 25% of tradition Haitian rebar stove emissions for both WBT and CCT
Time to boil during WBT using traditional starting practice is ¾ the time currently achieved with the
Haitian rebar stove.
Surfaces of the stove that will be contacted by stove operator should not exceed 50°C.
Less than 15 minutes to start and bring 2.5 liters of water to boil using traditional starting techniques.
Range of heat output 1-6 kW (heat transferred to pot).
Capable of using with pot diameters from 20-60 cm.
Withstand pot mass up to 25 kg.
Five or less tasks to maintain fire throughout a CCT after initial stove start.
Any part that will need to be replaced within a three year stove life should:
 Be less than $3.
 Require less than 60 minutes to replace.
 Be able to be replaced with no or simple hand tools.
Project 12442
Preliminary Specifications
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Stove weight should be less than 8 kg.
Stove volume should not exceed 0.2 m3.
Stove construction should be possible using basic Haitian fabrication capabilities
Survive 20x 2-meter drop tests.
Egonomics metrics?
Internal Specifications:
 Keep a minimum temperature gradient of 200°C across a Thermonanic TE (TEP1-1264-3.4)
thermoelectric module under peak power conditions (i.e. electrically loading module with the internal
resistance of the module.)
 Reach desired temperature gradient within 20 minutes of starting the fire.
 Consume less than 0.6 W (i.e. ideal case, 1 W absolute max) to operate all stove internal electrical loads
(i.e. fan and controls).
 Thermoelectric module never exceeds max operating temperature (380°C continuously and 400°C
intermittently on hot side and 200°C on cold side).
 Thermoelectric module is mechanically loaded evenly and loading does not exceed module failure
limit.
Project 12442
Project Deliverables
 An improved RIT stove design that has been tested and validated using a
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working prototype and shown to reduce fuel use and emissions by more than
50% from traditional Haitian stoves and is affordable and user friendly.
Stove must be tightly coupled to thermoelectric power unit prototype being
developed by P12441
Two prototype stoves to be sent to Haiti for field testing.
Full and easy to follow documentation on how to fabricate and assemble the
stove.
Intuitive end-user operation manual with instruction of how to start, maintain,
and operate the stove at optimal performance.
Project 12441
Thermoelectric Power Pack for Next Generation Cook Stove
 Build on the work done by project P10462 & P11462 to
develop power pack for that is electrically coupled to
P12442 stove and will supply sufficient power for fan
and auxiliary charging.
Needs:
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Affordable (<$10 at high production quantities)
Easy to operate: require little user interaction and simple and intuitive processes.
Compact, should be small so it does not extend too much from stove body.
Rugged, can handle being dropped by user multiple times, withstand harsh conditions such as rain and
high temperatures.
Heat resistant, can be mounted on stove framing with minimal loss in lifetime.
Durable, should operate for five or more years with a use rate of at least twice a day.
Able to charge multiple cell phones and other typical 5V USB loads over the course of a typical
institutional or vendor single stove use.
Minimize stove use for sole purpose of electric power generation: unit should be able to charge one
typical cell phone when no power is provided by thermoelectric to the fan.
Power fan used for a force air stove during entire stove operation.
Able to start fan multiple times in cases where there are multiple stove restarts.
Safe to operate: operator should not be injured during normal use and transport of the thermoelectric
power pack.
Project 12441
Preliminary Specifications
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Production cost: <$10 for materials and fabrication plus thermoelectric module at 1-10K
Operate 1.2W fan continuously during stove operation with a draw of 4-12VDC.
Power load using a Thermonanic TE Module (TEP1-1264-3.4) with a 20 minute warm-up
period with cold side of TE going from 30 to 100°C and the hot side from 30 to 300°C.
This is followed by steady state temperatures of 100°C and 300°C for 2.5 hours.
Package size for entire power pack except thermoelectric module is restricted to
3”x3”x1.5”
Unit should be less than 3 lbs.
Package should prevent damage or significant reduction in product life to electrical
components during a downpour.
A minimum of 7.0 Wh of charging capacity to auxiliary loads such as cell phones through
a standard USB connection over the course of a 3 hour cooking cycle
Sustain surface mounting temperatures up to 350°C.
Handle some sort of dynamic crush test
Survive 20 2-meter drop test.
Safety metrics?
Project 12441
Project Deliverables
 Two working thermoelectric power packs that are to be sent to Haiti for
field testing. The power pack must be nicely packaged and rugged.
These power packs must be fully coupled with the stove being developed
by P12442.
 Full set and intuitive set of documentation on how to fabricate and
assemble power pack units including necessary engineering pcb layouts
files.
 Intuitive operation manual should be provided for the end-user.
 Instructions on how to adjust fan voltage so future teams can adjust
design for different fans.
Classification of Cook Stoves
Open Fire
http://picasaweb.google.com/lh/photo/_D6z6UiS0hupX2pf1LIP5A
http://wings.interfree.it/html/Elbow.html
Rocket Stove
Classification of Cook Stoves
Gasifier Stove
Forced Draft Fan Stove
http://www.vrac.iastate.edu/ethos/files/ethos2009/Stove%20Developments/TLUD%20Gasifier.pdf
http://www.treehugger.com/files/2006/03/philips_smokele.php
Classification of Cook Stoves
Charcoal Stove
http://www.bioenergylists.org/stovesdoc/Ezzati/New%20Folder/metal.jpg
http://picasaweb.google.com/lh/photo/VhARzq11pifTNUljR09z6g?feat=embedwebsite
Liquid or Gas Fuel Stove
Stove Innovation
Adjustable skirt to improve heat
transfer
Outer pressurized make-up cavity
Air
flow
Inlet air perforations for improved
combustion
Inner combustion chamber
Thermoelectric module
Heat Sink
Small fan
Power storage and
conditioning/control
Potential auxiliary power supply
Why Forced Air?
Why Forced Air?
Why Forced Air?
Stove Testing
Water Boiling Test
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Bring 5 L of water to a
boil for a “Cold Start”
Bring a fresh 5 L of
water to a boil from a
“Hot Start”
From the “Hot Start,”
allow the water to
continue to boil for 45
minutes
Provides feedback on
fuel consumption and
thermal efficiency
Stove Testing
RIT Modified Water Boiling
Test
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Bring 2.5 L of water to boil
from a “Cold Start”
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Hold the boil for one minute
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Simmer Stage: Allow the
water to continue boiling for
20 minutes
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Allows to quickly verify
repeatability
Results
Water Temperature, Carbon Monoxide and Total
Weight
During Modified Water Boiling Test
600
13.6
13.4
500
13.2
400
13
12.8
Temperature (°C)
300
12.6
200
12.4
12.2
100
12
0
11.8
0
5
10
15
20
25
Time (min)
30
35
40
45
CO (ppm)
Total Weight (kg)
Results
Thermoelectric Benefits
 Modular, scalable
 Solid-state, no moving parts
 Operate over a range of temperatures
 Transient thermal sources
 Minimal maintenance
 No noise, vibration
Resources
Category
Source
Description
Resource Available
(mark with X)
Faculty
Rob Stevens
ME
Expertise in thermoelectrics and heat transfer
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John Wellin
ME
Expertise in DAQ, fluids, and fan characterization
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Brian Thorn
ISE
Product Sustainability
X
George Slack
EE
Power electronics
X
Jim Myers
Center for
Multidisciplinary
Studies
Haiti expert
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ME-Stevens
Lab for testing thermoelectric modules and subsystems. Lab does have
ventilation and some DAQ resources
X
DAQ system
ME-Stevens
A USB based DAQ system, laptop, thermocouples, etc. are available
through the Sustainable Energy Lab
X
Cook stove
test stand
SEL
X
Several
stoves
SEL
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Environment
Sustainable
Energy Lab
Equipment
Advise
 Identify the key hurdles and address them earlier
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rather than later.
Identify and focus on the critical parts and do not get
caught up with the trivial things.
Test early and test often. Test components and
subsystems before the entire system.
Learn from the past. Pick the brains of those with
experience.
Define your boundaries before you design, but be
flexible.