Georgia Institute of Technology TLUD Cook Stove

PROBLEM STATEMENT

Rural Nicaragauan families, as a result of cooking over open fires, face dwindling fuel supplies and numerous health issues

ASPIRATIONS

Replace traditional open fires with improved cook stoves that are capable of safely turning excess rice husk into cooking heat.

Three meals are eaten daily. Meals are cooked in the morning and are eaten throughout the day.

Smoke from the open �re 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.

Existing Conditions

DAY IN THE LIFE

DEMOGRAPHICS

160 families

8 milesfrom nearest large city (Chinandega)

50%

5 - 6 of women are single mothers

typical family size

THE VILLAGEThe conditions which the locals have to live with daily

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.

Pha

se O

neP

hase

Tw

oGASIFICATION

STOVE PRECEDENTS

1950 201019801960

1970 19902000

1950’sSmall cook stove deployment by Indian Government

1982 - 1992China disseminates 129 million improved cook stoves

1982 Larry Winiarski publishes Rocket Stove design principles

1988Samuel Baldwin publishes Design Principles for Wood Burning Cook Stoves

1988Paal Wendelbo invents TLUD stove

1985 Tom Reed invents TLUD stove

2008Alexis Belonio receives Rolex Award for Enterprise for first ever rice husk cook stove.

2010X Prize for cook stove design announced

2008Amy Smith perfects method for charcoal pro-duction from biomass

SPECSUse Locally Available Fuel

1. Shall use rice husk for fuel

Manufacturable, Maintainable2. Does not depend on stolen grid electricity3. Stable if knocked during operation4. Stable supports for large and small pots5. Able to run at night6. Will not degrade from exposure to rain7. Able to be transported from fabrication facility to homes8. Uses stainless steel, rebar, or ceramic9. Held together with weld or basic metalworking/ceramic- making operations10. Cost less than $15 to manufacture11. Only basic tools needed for assembly12. Experts able to produce at least 5 stoves per day

Turn Fuel into Heat13. Flame hot enough for boil water quickly14. Consume reasonable amount of rice husk per each meal cooked15. Flame can stand up to a gust of wind16. Amount of oxygen to flame does not vary unexpectedly17. Amount of oxygen to flame adequate for combustion

Transfer Heat to Food18. Stove walls must have low thermal capacity19. Interface to pot must direct hot flue gases around sides20. Adequate space to boil beans21. Adequate cooking surface for frying plantains22. Adequate cooking surface to reheat cooked food

Marketable Cooking Experience23. Tending operations required at most every seven minutes24. Tending operations take up at most 10% of cooking time25. Less than two hours of training required to acquire expert proficiency with stove operation26. Fits comfortably in Nicaraguan lean-tos27. Comfortable height for typical Nicaraguan female28. Emissions do not endanger the health of users over the course of a single stove use29. Hot surfaces unlikely to be touched accidently during normal operation30. No exposed sharp edges31. No pinch points32. Flame unlikely to be touched during normal operation33. Does not leave user light-headed after usage34. Culturally appropriate appearance35. Someone used to an open fire can be trained to use stove36. Able to be started with local starter materials37. Cleanup after use reasonable38. Able to gauge stove’s performance during usage39. Waste material is acceptable in community

CONTINUOUS

LOAD LIGHT COOK LOADTAP JIGGLE CLEAR

Every 15 MinutesWeak Flame 5 Minute Cycle

BATCH

LOAD LIGHT CLOSE IGNITE

Starts Syn GasProduction

DUMP

COOK

30 Minute Cycle

LOAD LIGHT CLOSE IGNITE

Reloading can be completed parallel to cooking

Burn Syn Gas

TENDING PATTERNS

FUNCTION TREE

AppropriateManufacturing

Techniques

AppropriateMaterials

Heat Starting/Stopping

Load/UnloadFuel

Fixable/Cleanable

Be Maintainable

Lower Emissionsto Safe Levels

Priced for MarketConsistent Provide SufficientCooking Surface

Be Easy to Operate

FunctionsConstraints

Cook

ProvideStability

ShieldHeat

ControlCookingProcess

Appealto

Aesthetics

Appealto User

ProduceHeat

Convert RiceHusk Fuelto Biogas

CombustBiogas

SupportCookware

ProtectUser

RESOURCES

Places where we turn for advice

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 the the reactor. Constant tapping may still be re-quired if bridging occurs.

Initial Sketches

NATURAL DRAFT TLUD

CHIMNEY

CONCENTRATORLID

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

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

CONCEPT REFINEMENT

Dimensioned ergonomic requirements

Quantified usability specifications

Fine-grained cost calculation

Performance metrics

REACTOR SIZINGStack effectdraft caused temperature difference

Venturi effectdraft caused by fluid flow past an opening

Ergun equationpressure 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.

SCHEDULE

Phase One:27

31

7

14

21

28 29

PHASE ONE

PHASE TWO

PHASE THREE

1

october

november

24progress

review

finalreview

Phase Two:

Phase Three:

Engineering ModelReactor “Tin-can” PrototypingUser-Centric Design

Integration of the three components within phase one

Final Documentation

CONCLUSIONA 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.

Georgia Institute of Technology TLUD Cook Stove

Business

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