By: Ali Brozek, Erika Union, Will Hitchcock, and Mike Deagen The Need: Nearly 3 billion people currently use open fires or unsafe stoves to cook Respiratory problems caused by these cooking methods are more fatal to children than malaria 1.6 million people die each year from inhaling smoke from cooking Source: http://www.stovetec.net/us/index.php?option=com_content&view=article&id=133&Itemid=684 The Mayon Turbo Stove: The Mayon Turbo Stove uses rice hulls as fuel Rice is the number one food crop in the world so rice hulls are an abundant agricultural waste The stove has the potential to provide an inexpensive and safer way to cook while slowing deforestation by using waste as fuel Source: http://www.reap-canada.com/bio_and_climate_3_3_1.htm Problems with the MTS: The Turbo Stove burns rice hulls very well but lacks an exhaust system and the gas the fuel releases when it burns is toxic The stoves are difficult to manufacture The design is physically unstable Image Source: http://bioenergylists.org/lotrau Group Purpose: Modify the existing plans for the Mayon turbo stove or last year’s Burninator in order to provide a stove that is: Safe: can be used in homes without dangers of smoke inhalation Inexpensive: easy to manufacture Efficient: runs on rice hulls Practical: boils water quickly Easy to use: starts burning quickly and easily! Testing the two existing stoves: Mayon Turbo Stove The Burninator Observations: Mayon Turbo Stove: Easy to start the fire, BUT: ○ Is unstable (falls over easily) ○ Has no system for safe exhaust removal ○ Is impractical for cooking Burninator More sturdy, shows promise for improvements BUT: ○ ○ ○ ○ Is very difficult to start the fire Has no system for safe exhaust removal Needs a cooking surface Fuel intake compartments and carburetor are inefficient Attribute: Weight (1-10): Rocket Stove (Burninator) Mayon Turbo Stove The Flamethrower (Modified Rocket Stove) Remove Little Ease Toxic Waste Manufactur Material of Temp. Fuel Smoke Heat ability Cost Use Output Safety Aesthetic Efficiency Total 8 2 3 9 5 2 4 5 7 8 2 6 5 6 7 4 4 4 8 8 7 4 5 7 6 7 4 8 2 3 6 5 5 49 6 4.77 6 6 4.61 2 6 6.69 4 1. Initial Testing Hamster Bedding Rice Hulls 2. Adjusted Carburetor 3. Used Plasma Cutter to separate the vertical chamber from its legs. 4. Welded the cone to the top of the chamber. 5. Added metal fittings to corners. 6. Detached the vertical chamber 7. Adjusted the Carburetor again 8. Added ramps to focus fuel. Shaping the Ramps The Shaped Ramps TIG Welding the Ramps In The Final Product 9. Put Mud along Cone to ensure airtight PS. Thanks Mud Stove Group! 10. Replaced chamber and adjusted feeder angles. Goal: Increase angle with a bigger opening (1” 2”) 11. Test Again!! 1. 2. 3. 4. Feed from one side Lighting from top Lighting from bottom Used a fan 12. Make a new stove including our observations! 1. 2. 3. 4. One feeder Make carburetor closer to feed to increase airflow Longer exhaust Lip at end to control fuel The Flamethrower! Tested: Doesn’t work Schematic of the “Flamethrower” • Simpler manufacturing than the Mayon Turbo Stove • Fuel intake on one side only • Ash is collected on the same side smokestack fuel hopper air intake ash collector Schematic of the “Flamethrower” • Simpler manufacturing than the Mayon Turbo Stove • Fuel intake on one side only • Ash is collected on the same side rice hulls twin pipes perforated aluminum sheet metal How Rice Hull Combustion Works • Initial kindling or fire starter necessary • Rice hulls outgas between 200-450°C (392842°F)1 • Below 200°C, negligible decomposition • At 200°C, darkish yellow • At 450°C, >90% of volatile matter separates • Proper fuel-to-air mixture sustains the burn 1 M.A. Hamad. “Thermal Characteristics of Rice Hulls.” 28 January 1981. Removing Hazardous Smoke • Rice hull ash and smoke contain silica, SiO2 • Same material as sand • Need to prevent inhalation of smoke • Exhaust system to redirect any smoke • The smokestack was effective, and the only smoke came out of the top • Next design needs to ensure good air quality Getting Rid of the Ash • Tap the side of the stove, gravity will cause more fuel to feed in and the ash will fall into the ash collector • For ease of use, the ash collector and fuel feed are facing the same side of the stove Ideal Air Flow • Air flows through the fuel, combines with the outgas, and combusts • Convection draws the hot air upward to the stovepipe, which draws more air through the intake to balance the pressures Actual Observed Air Flow • Air preferentially flows around the rice hull tray • Not enough air gets to the rice hulls to sustain a clean burn • The rice hulls simply smolder and produce a lot of smoke Redesign Considerations • • • • • • Air will flow in path of least resistance Maximize amount of useful air to the rice hulls Block areas where non-useful air can flow Effective method for removing ash Ability to CONTROL the fuel and/or air Air and heat flow through rice hulls is difficult • The thermal resistance R-value for rice hulls is about 3.0 per inch, good for insulation2 2 P. A. Olivier. “The Rice Hull House.” 2004. Recap Hot Potato Help Encourage Continuation of Project What does version 3.0 look like? Complete redesign or modification of the Flamethrower Focus on utilizing all airflow in the burn system -Exhaust system and cook-top -Integrate design with mud stove Questions???