jordan edwards | isaac lockman | peter nguyen | marc pare | jimmy vo | tyler wilson
Rural Nicaragauan families, as a result of cooking over open fires, face dwindling fuel supplies and numerous health issues
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.
DAY IN THE LIFE
8 milesfrom nearest large city (Chinandega)
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.
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
LOAD LIGHT COOK LOADTAP JIGGLE CLEAR
Every 15 MinutesWeak Flame 5 Minute Cycle
LOAD LIGHT CLOSE IGNITE
Starts Syn GasProduction
30 Minute Cycle
LOAD LIGHT CLOSE IGNITE
Reloading can be completed parallel to cooking
Burn Syn Gas
Lower Emissionsto Safe Levels
Priced for MarketConsistent Provide SufficientCooking Surface
Be Easy to Operate
Convert RiceHusk Fuelto Biogas
Places where we turn for advice
FUEL CHAMBER COMBUSTION
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.
NATURAL DRAFT TLUD
PRIMARY AIR DOOR
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.
PRIMARY AIR OPENING
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.
Dimensioned ergonomic requirements
Quantified usability specifications
Fine-grained cost calculation
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.