Alex English, September 1997
(missing pictures, Image5.JPG and Image1.jpg )
This shows the rather bizzare arangement I used to do a boiling water test on the venturi burner. It now has a 10cm diameter by 18cm tall cylindrical combustion chamber opening at about 5cm directly under the pot. As is often the case, it gave me some trouble getting started. So I lost a good deal of water boiling time. Without the additional chimney it operates without the intensive vortex or swirl action, however the flame was still fairly turbulent, thanks to the bluf body. That is ofcourse while the pot was off and I could see the flame. A thermo couple near the top of the combustion chamber gave fairly consistant readings of 1450+/-25F, until the TC quit working. That is 400F higher than the last test with the curvacious model. The CO2 was often up around 17-19% with CO over the 2000ppm limit. Having no adjustment on secondary air, I was forced to cut back on primary air. This brought CO2 down to 11-13% and CO to 125-350ppm.(CO/CO2 of .002) At the higher CO2 levels (and the pot removed) the flames extend out the top of the combustion chamber. At the lower levels they did not. There was no visible smoke at either time. In spite of early fumbleing it still managed to boil off 7.25 lbs of water with 7.75 lbs of wood. Certainly no efficiency breakthrough. Probably a food burning breakthrough. On a positive note, CO was lower than I expected.
This burner will soon go off to school where a 4th year engineering student at Queens will try to measure its performance and assist in its optimization. The way it looks now it certainly isn't "everymans" stove. I do however think that a practical low emissions burner for the charcoal maker is a possibility.
This picture shows the veiw into the top. The pot is lifted out and over to reveal the 10cm diameter combustion chamber. The orange hue is the flame. The metal cross supports the pot and distributes the gasses