THE MODIFIED

TURBO STOVE:

THE FLAMETHRO

WERBy: 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 dieeach 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 hullsare an abundant agriculturalwaste

The stove has the potential to provide an inexpensiveand safer way to cook while slowing deforestation by usingwaste 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 isphysically 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 inhalationInexpensive: easy to manufactureEfficient: runs on rice hulls Practical: boils water quicklyEasy 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

BurninatorMore 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:

Remove Toxic

Smoke

Little Waste Heat

Manufacturability

Material Cost

Easeof

UseTemp. Output SafetyAesthetic

Fuel Efficiency Total

Weight (1-10): 8 5 7 5 4 7 6 2 5 49

Rocket Stove (Burninator) 2 2 8 6 4 4 7 3 6

4.776

Mayon Turbo Stove 3 4 2 7 8 5 4 6 6

4.612

The Flamethrower (Modified Rocket Stove) 9 5 6 4 8 7 8 5 6

6.694

What did we actually do this quarter??

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

PS. Thanks Mud Stove Group!

9. Put Mud along Cone to ensure airtight

10. Replaced chamber and adjusted feeder angles.

Goal: Increase angle with a bigger opening (1” 2”)

11. Test Again!!1. Feed from one side2. Lighting from top3. Lighting from bottom4. Used a fan

12. Make a new stove including our observations!

1. One feeder2. Make carburetor

closer to feed to increase airflow

3. Longer exhaust4. 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

ash collector

air intake

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 (392-

842°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???