[Stoves] Annular Crosscurrent Burner for ND-TLUD

Julien Winter winter.julien at gmail.com
Tue Mar 17 09:38:57 CDT 2015


Hello Stovers;

Attached is another experimental vignette.  This one compares two types of
pyrogas burner.  The abstract is as follows.

=====

An annular cross-current gas burner (AB) for a ND-TLUD was designed with a
central distributor for secondary air to increase the mixing of pyrogas and
secondary air at the base of the gas flame.  However, it was expected that
this central distributor would create a resistance to the flow of hot
gasses, thus slow down the rate of gasification in the TLUD.  The central
distributor could also reduced the area of gas flame ‘visible’ to the
bottom of a cooking pot, so it could reduce the efficiency of radiant
energy transfer from the flame to a cooking pot.  Tests were run to compare
the AB to a peripheral cross-current burner (PB) designed to minimized
these limitations.    The AB did slow down the rate of gasification
compared to the PB, but the AB made the TLUD safer to use by preventing
excessive gasification rates.   Energy-transfer was compared by placing
thermocouples above the gas flame.  The temperature of the AB was slightly
lower than the PB at any given rate of gasification, so it was predicted
that under actual cooking conditions, the AB will be moderately less
efficient than the PB.  However, any decrease in efficiency may be a small
price to pay if the AB is shown to make substantive reductions in the
emission of hazardous CO and fine soot particles.

=====

This was a small experiment, that ended up posing as many questions as it
answered.  Does the composition of pyrogas really change during the coarse
of a burn?  How reliable are the thermocouples at predicting heat transfer
to a pot?   The decrease in riser temperature observed at higher grate
apertures has implications for measuring the turndown ratio of TLUD stoves.


If you want to build a central distributor, you can use a small stainless
steel food bowel, and the wand of a vacuum cleaner (beg forgiveness later).

Cheers,
Julien


-- 
Julien Winter
Cobourg, ON, CANADA
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