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Post by Zoli on Dec 26, 2021 13:46:59 GMT -8
I wish you a Happy New Year!
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Post by Jura on Dec 29, 2021 13:24:55 GMT -8
What are the ribs for? I wouldn't put them on the top as it would interfere with the vortex, What I Can recall from the photos hof posted in his thread this ribs were nivelated with a CFB placed on the roof of the afterburner. BTW. a few days (weeks?) without peeping into the forum and I can see enormous changes (the idea of secondary air in the afterburner)
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Post by Vortex on Dec 29, 2021 16:00:16 GMT -8
Keep up Rafał I can see now what the ribs are for with the later pics hof posted. The secondary air thing was originally just an experiment for curiosities sake, but this version has turned out to be a really interesting development. I'll try and sum it up for you tomorrow when I'm not so tired.
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Post by Vortex on Dec 30, 2021 6:00:35 GMT -8
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Post by Vortex on Jan 1, 2022 14:57:04 GMT -8
Today I raised the afterburner 20mm so I could try secondary air up through the floor at positions C & D, but ended up making them on the insides of the port at I & J: (5mm high by 120mm long - 600 mm2 / approx 1 inch square on each side - total 6.8% CSA). I kept the lower side holes (A & B) but removed all the rear wall holes. I raised the afterburner by adding a 20mm layer of vermiculite board to the floor, this had the added advantage of insulating the afterburner floor from the roof of the firebox. The results were excellent. In the second half of the burn you could see the streamers of flame coming from the holes inside the port, but not from the side holes (A & B ), even though they are fed from the same source. I think this must be because the venturi effect is stronger in the port and so draws more air from there. Next I think I will try also adding secondary air at positions C & D and G & H.
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Post by hof on Jan 2, 2022 3:10:58 GMT -8
Got video?
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Post by Vortex on Jan 2, 2022 12:56:40 GMT -8
Not yet unfortunately, my camera battery was flat yesterday, today the right side of the afterburner wall fell inwards and blocked the secondary air channel just after I lit the stove, so hopefully third time lucky tomorrow.
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Post by Vortex on Jan 3, 2022 11:45:18 GMT -8
I managed to capture a few video clips of the secondary air burning from the inlets in the sides of the port, they're not the best quality, but it's something for you until I can get a clearer one uploaded. The flame is mostly coming from the right-hand side as it's nearer to the source. VIDEO HERE
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Post by hof on Jan 3, 2022 13:07:38 GMT -8
I used 20mm vermiculite boards on my 4" stoves. The 40mm thickness on the 6" is just for strength. I've thought about doing it next time with two 20mm layers of kiln shelves, with the top layer with the join across in front of the port (so the top layer would be in 3 pieces). What are the ribs for? I wouldn't put them on the top as it would interfere with the vortex, on the underside should be OK, might even add a bid more mixing for your secondary air. Thank you very much. Flame looks MUCH clearer.
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Post by Vortex on Jan 3, 2022 14:10:36 GMT -8
Yes, the color of the vortex flame is very different with secondary air to the afterburner, it's a much brighter orange. Next I will try and do a video of the vortex while turning the secondary air on and off to show a comparison.
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Post by Vortex on Jan 4, 2022 12:23:24 GMT -8
Video starts with full 10% CSA secondary air directly into the afterburner, which is then turned off completely at 9 seconds and then back on full at 16 seconds: VIDEO HERE
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tferr
Junior Member
Posts: 69
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Post by tferr on Jan 4, 2022 14:27:49 GMT -8
Wow what a difference! I am still humming and hauing on how I am going to do the secondary air.
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Post by Dan (Upstate NY, USA) on Jan 5, 2022 5:00:41 GMT -8
What does the graph look like for a whole burn with and without the secondary air in the throat?
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Post by marcios on Jan 5, 2022 6:31:01 GMT -8
Video starts with full 10% CSA secondary air directly into the afterburner, which is then turned off completely at 9 seconds and then back on full at 16 seconds: VIDEO HEREHow did the secondary air path look from the inlet to the stove? Do you have pictures/drawings of it? Some time ago I saw a wood gasification with the secondary air arriving at the port by iron pipe passing through the firebox, so as to be preheated, would be an idea no?
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Post by Vortex on Jan 5, 2022 11:57:59 GMT -8
Wow what a difference! I am still humming and hauing on how I am going to do the secondary air. I'd make it big, about 20% CSA so the air has time to heat inside it, and make it so it has an equal length path to both sides. What does the graph look like for a whole burn with and without the secondary air in the throat? Are you specifically asking about secondary air introduced through the sides of the port as compared to just the walls of the afterburner? I haven't done any burns with just secondary air to the sides of the port yet, they've all been combined with it to the side walls as well. There are graphs which make it look better and worse, there are so many other variables it takes time to work out the overall effects. Air through the sides of the port does seem to mix more effectively than from the side walls alone. I need to make a better secondary air supply though, at the moment it is closer to one side and seems to favor that side more. How did the secondary air path look from the inlet to the stove? Do you have pictures/drawings of it? Some time ago I saw a wood gasification with the secondary air arriving at the port by iron pipe passing through the firebox, so as to be preheated, would be an idea no? I would like to improve the pre-heating of it, at the moment it goes behind and under the vermiculite boards which glow red hot, so will be getting warmed up quite well - as good as through a metal pipe in the firebox anyway, but I think it could still be improved upon. There is a post here that shows the secondary air path to the afterburner side walls. I've added the secondary air to the insides of the port since then. To get to them it just goes under the side walls and between vermiculite boards and the firebox roof each side of the top of the port: donkey32.proboards.com/post/37052/thread
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