Jonathan, A couple things to remember...That water was about 1000 times denser than air and at 40psi. Small changes are more likely to make a bigger difference.
If you get to a mass production scenario you will likely find it cheaper to laser the holes, in which case you will have no burr. I just had some sheetmetal lasered and it was downright cheap, especially compared to making punching tools. Stephen -----Original Message----- From: thomas reed <[email protected]> To: Jonathan Otto <[email protected]>; Discussion of biomass cooking stoves <[email protected]>; gasification <[email protected]> Sent: Fri, Oct 1, 2010 9:50 am Subject: Re: [Gasification] Thoughts in a cold shower Dear Jonathan and All: Very interesting observation that the upstream facing jagged holes almost ompletely blocked the water (air?) flow, while facing downstream they unctioned better (but not good). I'm very sensitive to this, having made an elegant natural draft pellet/wood tove from a 4 1/4" diameter by 6 3/4" high Dole Pineapple juice can. I'll eport on the tests later. However, I drilled 12 1/8" primary air holes an nch up from the bottom (to allow combustion to stop well above the bottom) nd 12 3/16" secondary air holes 3" below the top. I used the can lid to ake a draft enhancer/pot support. I drilled these 24 holes using a step drill that has many diameters in ncreasing steps. (If you haven't got one, get it at Harbor Freight). But, noticed some jagged metal on the inside and took long drills and waggled hem around in the holes until they were smooth inside and out, since this as a research project. (Results to be published when I digest them.) I tested the new stove with pellets. Big mistake. They burned for 2 hours, ostly at a level of 1600 watts, as tested by observing rate of weight loss n a digital scale. (1 g/min of biomass combustion generates 20 kJ/g or 333 atts. I was burning about 5 g/min. The stove held 600 g of pellets.) More to come when digested... TOM REED Pyrologist On Fri, Oct 1, 2010 at 9:00 AM, Jonathan Otto <[email protected]>wrote: > *Report (written while flying at 4,235 feet above sea level over Lake Victoria --I’m looking over the pilot’s shoulder -- in a Cessna 12-seater en route from Bukoba to Mwanza), of a minor observation made in the shower.* When I tried to take a shower in our little hotel last night all the water ran out around the edges of the shower head rather than through the holes provided. Thinking the holes may be clogged, I unscrewed the unit -- which looked like the spout for a local tinsmith’s handmade watering can -- and popped off the flat perforated disk. It turned out the holes were not clogged at all. The holes had been made with a punching tool and then the disk was inserted upside down, so that the jagged edges of the holes faced up towards the stream of descending water while their smooth side was facing downward. In layman’s terms, it seemed that the water had no time to find its way around the jagged edges and through the holes before the pressure forced it out of the showerhead around the ill-fitted edges of the disk. I flipped the disk over, reinserted it into to the unit, screwed that back onto the supply pipe, optimistically turned on the faucet marked hot and voila! – fine streams of rather tepid water spouted from every hole. Of course, flows of water and air behave very differently; however, as the ever-colder water washed over me I wondered: would it make any significant difference in the performance of the J seed TLUD if the secondary air holes were punched with an awl instead of drilled. The dimpled rim on the exterior side of each hole might slightly speed up the air inflow bending to enter. The slightly protruding and perhaps slightly irregular inner rim of the holes might create a bit of additional turbulence. Then I wondered if holes of various diameters would cause air entering the chamber to behave differently and cause some more turbulence. Next thought: if punching holes had no positive impact on air intake, can we determine that there is at least no *negative* impact of punched air intake holes. Why worry about that? Because producing all the required holes at once in a piece of sheet metal that is secured to a purpose-made punching jig may be a reliable way for tinsmiths to rapidly and accurately reproduce the winning design of the ever-evolving Seattle J seed stove. On the other hand this bit of random cogitation whilst engaged in daily ablutions may simply be a fine example of why some people make/test/perfect stoves, and others trudge through their so-called careers as development bureaucrats; and why I, who seem ensconced in the latter category, should stick to writing the great American funding proposal so we can disseminate the ingenious cooking appliance soon to be produced by the Seattle J seed stove team. Over two youse guys, Jonathan -- OTE: PLEASE CHANGE MY ADDRESS TO [email protected] Dr. Thomas B. Reed he Biomass Energy Foundation EF, BEC, BER ______________________________________________ asification mailing list [email protected] ttp://listserv.repp.org/mailman/listinfo/gasification_listserv.repp.org ttp://gasifiers.bioenergylists.org ttp://info.bioenergylists.org UNSUBSCRIBE HERE; ttp://listserv.repp.org/mailman/listinfo/gasification_listserv.repp.org _______________________________________________ Gasification mailing list [email protected] http://listserv.repp.org/mailman/listinfo/gasification_listserv.repp.org http://gasifiers.bioenergylists.org http://info.bioenergylists.org UNSUBSCRIBE HERE; http://listserv.repp.org/mailman/listinfo/gasification_listserv.repp.org
