Sam Bentson and David Evitt with the new Jet-Flame
Sam Bentson and David Evitt with the new Jet-Flame
Sam Bentson, ARC Lab Manager, and David Evitt, ASAT COO, developed the Jet-Flame with Shengzhou Stove Manufacturer and Dr. Dan Lieberman and Dr. Mike Barbour at the Gates funded Global Health Labs

The cast iron Jet-Flame sends 30 jets of pre-heated air up into the burning charcoal and wood in an open fire, sand/clay stove, or in a Rocket stove. It is patterned after industrial burners that position jets of primary air underneath the fuel bed to clean up combustion. Both Underfeed Stokers and Fluidized Bed Boilers use primary air that enters the fuel bed from underneath the fire.

In 2013, with DOE funding, ARC built a bottom-air-only prototype stove and has been experimenting with improving the technique, resulting in the Jet-Flame combustion chamber accessory manufactured by SSM in China. There are several advantages in a bottom-air-only approach. The jets of air flow into the fuel bed from holes in the floor of the combustion chamber. Since the pre-heated air flows vertically, back-drafting out of the fuel door in a Rocket type stove is easier to overcome. The jets of air super-heat the charcoal layer underneath the sticks of wood. The hot jets of air emerge from the charcoal and pierce the laminar flames emitted by the wood creating turbulent eddies that stir up the flames to enhance the speed of mixing and combustion. The turbulent combustion zone creates short, intense flames that burn the fuel more completely before they cool off too much to sustain combustion. The increased velocity of the higher temperature flue gases also improves heat transfer efficiency.

Winiarski sunken pot Rocket stove with chimney
Winiarski sunken pot Rocket stove

When the Winiarski sunken pot Rocket stove with chimney is combined with the Jet-Flame the increase in combustion efficiency results in a truly improved stove with the ability to protect health. Since the stove and chimney do not leak in lab tests the stove does not emit fugitive emissions into the kitchen. The stove achieves all ISO 19867 Tier 5 ratings for both thermal efficiency and emissions of CO and PM2.5.

In 2004, ARC was hired by the Shell Foundation to bring the Rocket stove to India. Protecting health was a component of the project. Unfortunately, the natural draft Rocket stove was not clean enough burning to accomplish the task. Higher temperatures and a lot more mixing were needed. We wish that, when asked for a health protecting stove, we had been this far along. It has taken a while to make some progress. 

Test results of the Jet-Flame with a vented Rocket stove.
Test Results of the vented (with chimney) sunken pot Rocket with Jet-Flame

Integrated stove for heating, cooking, electricity

Watch a video of the downdraft rocket stove that ASAT Inc. will show in Washington D.C. at the Alliance for Green Heat/DOE sponsored Wood Stove Design Challenge from Nov 9 to 13. ASAT gratefully acknowledges support from the US Environmental Protection Agency under EPA SBIR contract number EPD18009.


See an introduction to the Integrated Stove on Youtube: https://youtu.be/LUH3LMTG1OM

Long sticks are placed vertically in the combustion chamber where only the tips burn. A weight pushes the wood down as the ends turn into soft charcoal. Cooling fins on the top half of the feed tube help keep only the tips of the sticks burning. The room air is heated by the tall heat exchanger and cooking is possible on top of the cylinder.

The stove features a thermoelectric generator near the coals to create 18 W of electricity when the stove is running at its 10 kW high power setting. The electricity is distributed to two USB ports for high speed cell phone charging and LED lighting. Aluminum fins protrude into the combustion chamber to bring heat to the hot side of the generator, and a radiator on the bottom of the stove draws the heat away from the cold side and into the room.

It has been quite nice to have a warm lab as the temperature outside drops. You will certainly enjoy it during our post ETHOS TLUD summit.

 

Rocket stoves have been shown to be much cleaner when burning at medium power (Jetter, et al 2012, Agenbroad, 2010). For this reason, a fence located at the back of the combustion chamber in the new DOE funded Sunken Pot Rocket stove allows only 8cm of the tips of the sticks to burn. The outer portion of the stick remains too cold to make more wood gas. The stove is insulated with spirals of stainless and aluminum foil to increase the R-value and to decrease lost energy into the stove body. The riser tube above the combustion chamber is 10cm in diameter and the depth of the fuel magazine is shortened to 11cm.