[Stoves] Rapid mixing-premixing trial

alex english aenglish444 at gmail.com
Sun Oct 2 13:14:35 CDT 2016


Listers,
This follows from previous comments on this topic.

So testing the so called premix burner with  different TLUD fuel condition
yielded a very different result.

Using a 5.5 inch inside diameter pipe, 7.5 inches tall as a fuel chamber.
https://goo.gl/photos/kMhkJUTaSvHYsA7T9

With the same burner assembly;
https://goo.gl/photos/JYP5jDTkNqKvZK9h9

With 5 or 6 inches of wood pellet depth it burned for roughly 50 minutes.

Here is a video of the flame;
https://www.youtube.com/watch?v=71mt-wUHadc&feature=youtu.be

The primary under fuel air was not limited, Particles are entrained in the
gas, showing up as sparks. The temperature in the reaction zone is likely
800C or more. This is a guess based on data from past experience. The flame
speed appears to be faster and attaches low in the burner,  just after the
secondary air, with essentially little or no premixing. I think this
condition and the previous one with the blue flame represent two ends of a
spectrum for natural draft tluds.

I have seen some conflicting evidence about gas species from gasification
and pyrolysis of wood at different temperatures. It is likely that there is
more C02 at the lower superficial velocity/temperature condition. That
might be sufficient to lower flame speed. The same for the  lower hydrogen
content.??  I have flame speeds for many gasses. Any references or theories
about the what is burning here??

Looking closely at the blue flame video I think I see mixing pattern with a
name. Without my providing the name, I would like to know what other people
see. Hint it isn't "vortex".
Alex
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