[Stoves] Trials on TLUD gas burners

[Ronal W. Larson]

Julien,  cc list:

	Nice report.  Thanks for sharing. 

	 1.  My conclusion is that the best results were from what you call the “rectangular hole design” - generally the right-most in your figures.  I put the difference down to the fact that you are blocking the central part of the combustion area, so the pyrolysis gases are much closer to the secondary air supplies.  Call this A.

	Next best is what you called concentrator below  (the left one - which has 16 air ports (presumably smaller??).  Call this B.  (Do you see any preference for 16 over 8 secondary air ports?

	It seems very wrong to place concentrators above the secondary air ports.  Call this C.

	2.   In your Figure 3, this is B, C, A from left to right.  (OK?)  The middle figure is the worst?

	My criterion is the set of photos in Figure 4, with very clean combustion for A, next best for B, and bad for C.  In Figure 4, in the top row, B is at the right, and th bottom row, you have C left and A right.  I see A as better than the open chimney - but no videos or photos of the open chimney in action.  Can you compare A and open further?

	3.    In the still photo and the two videos, I perceive a phenomenon I have seen before (with Paul Olivier’s deign).   By looking closely, counterintuitively, the flames seem attached  NOT over the gas apertures, but rather between them.  I think this is true in all cases but can’t see the case C “attachment” points.  Except in private dialogs with Paul O, I have not seen this stated before in print  - and don’t know if it should be encouraged or discouraged.   I believe if your large outer air ports in A, were made narrower and longer in a circumferential direction, there might be a more continuous flame, through which little pyrolysis gas could pass without being combusted.

	My guess is that you now have considerable excess air, and so could get better het transfer to the cook pot, with less secondary air aperture.

	4.  In the design A, all the holes cut be cut so as to create a swirl - which might give improved combustion - and allow a shorter chimney.

	5.   You would have a more “salable” design if you could control primary air.  A short piece (or two?) of electrical conduit (1/2 “ ID, 7/8’OD - or larger??) costs hardly anything and could be fitted with a conical plug to control primary air.  It would have to penetrate the vertical walls of both cans, but wouldn’t have to have a really tight fit - just a lot more control through the pipe rather than air slipping around it.   This would replace your present multi-hole bottom, and you would have to put in a different “holey” plate for the pellets to rest on.  Of interest to all would be how large a TDR (turn down ratio) you could achieve (run for 1.5 hours??) 

	6.  So lots of suggestions that need not be on your plate.  But I think you are really on to something with A vs B or C.  Congratulations for what you have already accomplished.

Ron



On May 1, 2014, at 9:22 PM, Julien Winter <winter.julien at gmail.com> wrote:

> Hello stovers;
> 
> I have just finished some tinkering on natural-draft, TLUD gas burners.  I expect that much, if not all of what I have done, has been done before, but it doesn't hurt to see some results to stimulate discussion.  The results of my tinkerings are attached as a pdf.
> 
> I don't think my interpretations are complete, and I must revisit the paper by Birzer et al. (2013).  However, it is past my bedtime.
> 
> Cheers,
> Julien
> 
> 
> -- 
> Julien Winter
> Cobourg, ON, CANADA
> <Test of Gas Burners on a ND-TLUD.pdf>_______________________________________________
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