List: In my last message: I said: " I watched the testing of an interesting stove designed by Kirk Harris (from La Rosa (?) CA. This was much larger version of a camping stove he brought. Good results on abbreviated testing. I'll write a separate report on this design as it had several features I have not seen elsewhere. "
#1 was his means of controlling primary air: a paper clip of the large spring type attached to a circumferential band near the bottom. Had a single large "square" hole in the band for his camping stove (that allowed for adding fuel in a rocket manner, if needed). In the larger, impromptu verson he had only three equally spaced primary air holes. It seemed very easy to squeeze the paper clip to open the strap enough to rotate it for changing primary air. I am not sure how the strap was attached to the clip - maybe just two right angle bends in the loop ends. #2 was his use of "rock wool" for insulation. This prevented use of the gap between inner and outer cylinders for preheating secondary air, but he believes the tradeoff favors the added insulation. Only TLUD I have seen with this approach. Should be possible to prove one way or another with some modeling and or testng.. He still has some secondary air preheating as the secondary enters the combustion region. I heard one stove expert talk aganst this idea - so it needs more trials. #3 was use of swirl achieved by the entry angle of the secondary air. Many TLUDs with this swirl, but not at this stove camp. #4 was use of a rockwool (?) "stove rope" for sealing the top surface. Like #2, this was from a "Bucks" stove store. #5 was use of cans mostly throughout (had a small can to get extra draft) but used a "coil" of stainless steel (not a tin can) for the innermost surface of the camping stove to have better lifetime. Not sure on the larger unit, where everything was scrounged from Aprovecho stock. #6. As noted in #1, he could add fuel from the bottom with the camp stove. Not many (if any) TLUDs doing this. Reason in part that camping stoves needn't save char . $7 This Is the big one:- I have never seen in any other TLUD. Kirk had a third set of air holes that he called "intermediate" - that all pointed (by the bending of the slits in the stainless) downward. They were located slightly below the secondary air holes of #3. They were designed to burn up the char - not what I want for TLUDs, but quite appropriate for camping stoves. In most TLUDs that burn the char, the primary air supply is cranked wide open to prevent smoking; the problem is the heat release is far from the pot.. KirK does the opposite, mostly closing the (former) primary air holes. He finds a bright flame from the top combustion of the produced char . In the single run I saw, there was very little char left. We agreed that the TLUD-world needs a better handle on pressure differences within any TLUD . Other - Kirk showed me a 2-page writeup, with some of the above. All in all, Kirk has thought a lot of this through very well - for those who want little char. There are still several lessons for those of us who want the cahr. Ron
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