4. Three meals are eaten
daily. Meals are cooked
in the morning and are
eaten throughout the
day.
Smoke from the open fire contains
harmful chemicals and collects
inside the shed.
Meals consist primarily of
rice and beans and tortillas.
Villagers whose income
is restricted to a dollar
a day have to collect
wood on a daily basis.
The average
family consists
of six people.
DAY INTHE LIFE
7. Combustion occurs in two
distinct phases
By providing heat to biomass
in the absence of oxygen, the
two stages can be separated.
Gasification is this two stage process. A
gasification stove generally burns cleaner than a
direct combustion stove and produces biochar
instead of ash.
PhaseOnePhaseTwo
GASIFICATION
8. STOVE PRECEDENTS
1950 2010
19801960
1970 1990
2000
1950’s
Small cook stove
deployment by Indian
Government
1982 - 1992
China disseminates 129
million improved cook
stoves
1982
Larry Winiarski
publishes Rocket Stove
design principles
1988
Samuel Baldwin publishes
Design Principles for Wood
Burning Cook Stoves
1988
Paal Wendelbo
invents TLUD stove
1985
Tom Reed invents
TLUD stove
2008
Alexis Belonio receives
Rolex Award for
Enterprise for first
ever rice husk cook
stove.
2010
X Prize for cook stove
design announced
2008
Amy Smith perfects
method for charcoal pro-
duction from biomass
9. SPECS
Use Locally Available Fuel
1. Shall use rice husk for fuel
Manufacturable, Maintainable
2. Does not depend on stolen grid electricity
3. Stable if knocked during operation
4. Stable supports for large and small pots
5. Able to run at night
6. Will not degrade from exposure to rain
7. Able to be transported from fabrication facility to homes
8. Uses stainless steel, rebar, or ceramic
9. Held together with weld or basic metalworking/ceramic-
making operations
10. Cost less than $15 to manufacture
11. Only basic tools needed for assembly
12. Experts able to produce at least 5 stoves per day
Turn Fuel into Heat
13. Flame hot enough for boil water quickly
14. Consume reasonable amount of rice husk per each meal
cooked
15. Flame can stand up to a gust of wind
16. Amount of oxygen to flame does not vary unexpectedly
17. Amount of oxygen to flame adequate for combustion
Transfer Heat to Food
18. Stove walls must have low thermal capacity
19. Interface to pot must direct hot flue gases around sides
20. Adequate space to boil beans
21. Adequate cooking surface for frying plantains
22. Adequate cooking surface to reheat cooked food
Marketable Cooking Experience
23. Tending operations required at most every seven minutes
24. Tending operations take up at most 10% of cooking time
25. Less than two hours of training required to acquire expert
proficiency with stove operation
26. Fits comfortably in Nicaraguan lean-tos
27. Comfortable height for typical Nicaraguan female
28. Emissions do not endanger the health of users over the course
of a single stove use
29. Hot surfaces unlikely to be touched accidently during normal
operation
30. No exposed sharp edges
31. No pinch points
32. Flame unlikely to be touched during normal operation
33. Does not leave user light-headed after usage
34. Culturally appropriate appearance
35. Someone used to an open fire can be trained to use stove
36. Able to be started with local starter materials
37. Cleanup after use reasonable
38. Able to gauge stove’s performance during usage
39. Waste material is acceptable in community
10. CONTINUOUS
LOAD LIGHT COOK LOADTAP JIGGLE CLEAR
Every 15 MinutesWeak Flame 5 Minute Cycle
BATCH
LOAD LIGHT CLOSE IGNITE
Starts Syn Gas
Production
DUMP
COOK
30 Minute Cycle
LOAD LIGHT CLOSE IGNITE
Reloading can be completed parallel to cooking
Burn Syn Gas
TENDING PATTERNS
13. CONTINUOUS
FUEL CUTOFF
BURNER
FUEL CUTOFF
FUEL CHAMBER
FUEL
CHAMBER COMBUSTION
CHAMBER
CHAR
This continuous stove based design allows for
easier loading of fuel.The sloped path of the
fuel chamber allows the fuel to flow straight
into the reactor of the stove. By allowing the
fuel to come only from one direction, bridging
is reduced. The design also features a fuel
cutoff that will stop the fuel from flowing into
thethe reactor. Constant tapping may still be re-
quired if bridging occurs.
Initial Sketches
14. NATURAL DRAFTTLUD
CHIMNEY
CONCENTRATOR
LID
PRIMARY AIR DOOR
FUEL
CHAMBER
PRIMARY AIR
This TLUD based design promotes natural
draft to fuel the combustion of rice husk. The
fuel chamber is much smaller to allow more
primary air to travel through the fuel. This
allows the user to easily start the stove con-
sistantly. Due to the smaller fuel chamber, re-
loading would occur more frequently .The
simplicity of the design makes this stove farely
easy to fabricate with minimal material.
Initial Sketches
15. CROSS DRAFT
PRIMARY AIR
OPENING
CHAR
COMPARTMENT
FUEL CHAMBER
CHAR
PRIMARY
AIR
SYNGAS
This cross-draft based design promotes natu-
ral draft to fuel the combustion of rice husk.
Contrasting to the TLUD design, the air, in-
stead of moving top to bottom or bottom to
top, travels sideways through the fuel. This is
benefitial for users who wish to add an addi-
tional burner.The fuel chamber is level with
the burner to allow easier fuel reloading.
Startin the stove can be difficult though and
can produce a lot of smoke.
FUEL
CHAMBER
Initial Sketches
17. REACTOR SIZING
Stack effect
draftcaused temperature difference
Venturi effect
draftcaused by fluid flow past an opening
Ergun equation
pressure resistance by a packed bed
Preliminary calculations show that a 3 ft. chimney can pull enough draft for a
12 in. tall stove. However, the model assumes lossless, laminar flow.
18. SCHEDULE
Phase One:
27
31
7
14
21
28 29
PHASE ONE
PHASETWO
PHASETHREE
1
october
november
24
progress
review
final
review
Phase Two:
Phase Three:
Engineering Model
Reactor “Tin-can” Prototyping
User-Centric Design
Integration of the three
components within phase one
Final Documentation
19. CONCLUSION
A clever combination of existing technology
with a close eye for user experience embodies
a form that could improve the lives of hundreds
in rural Nicaragua.
