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Post by Vortex on Apr 24, 2020 10:27:56 GMT -8
Are those corrugations on side walls applied intentionally to add more turbulence or you just happened to have such piece of material? Seeing the chart my blance weighting DSR II and Vortex cores leans towards the last one. Have you ever tried to continue measurements till the end of coaling phase? Hi Rafał, It's 20mm thick vermiculite board bought locally, it has one flat side and the other corrugated. I put it that way around in the hope of more turbulence. I want to try lining the whole afterburner with it to see how it behaves, but it'll have to wait till next winter now. The chart is an average one, some of them the CO startup peaks are as low as 500ppm if everything is just right. I stop the Testo when the double vortex goes out in the afterburner. On the graphs it looks like I'm stopping it sooner than the others because I'm controlling the air to keep the double vortex spinning as long as possible. If you look at that previous graph I posted where I opened the air back up at the end, you can see the CO2 drops by half almost immediately to the 4% / 17% O2 used as the indicator for ending the tests. |
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Post by Vortex on Apr 24, 2020 10:44:17 GMT -8
Thanks Trev. Going back through your thread I see that the shelf is made of 1" ceramic fibre board and 1" cf wool so a total of just over 5cm thick. The shelf is optimally 75mm back from the front of the afterburner window and 230mm is the width of the Afterburner and Top Chamber so the 40mm is the height between the shelf and the roof of the Top Chamber, visible, seen from above, in a photo on page 36 where you removed the cooktop plate. In the same photo on page 36 we can see the exit from the Top Chamber into the cooktop plenum so the area where heat becomes usable for cooking. Hope I've got that right. In your last photo, looking through the afterburner window, it looks like the the afterburner is narrower at the back, but maybe this is just an illusion? One last thing, the various additions of, I guess CFB or CF wool are to shape the gas path. The function of most is pretty clear but what about the triangular shaped one sitting towards the front of the shelf and across its width. It must have the effect of slightly narrowing the 40mm between the shelf and the roof of the Top Chamber. Is that correct? Hope I'm not being annoying by asking so many questions and, as always, thanks for generously sharing your design and findings. No bother with the questions, helps me to see it from another perspective. That drawing needs updating, the shelf is 4-1/4" /110mm back from the glass. I found 4-1/4" was the minimum I could have without the heat etching the inside of the afterburner window glass. The afterburner is actually 1/4" narrower at the front - wasn't intentional just ended up that way: 9" wide at rear, 8-3/4" at the front. No idea if it helps or not. The triangular piece is what forms the afterburner exit 3"/75mm back from the front edge of the top of the shelf, I used it just because it was handy. The shape should help push the heat against the underside of the hotplate though. |
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Post by fishalive12345 on Apr 26, 2020 1:37:03 GMT -8
I think I got lost somewhere along the way in the development. The photos I was referring to on page 36 are of a previous version of your stove, before the aryan afterburner. I think I'm getting the idea!
The roof of the afterburner is the underside of the cookplate. Is that right? So the bottom of the port is the triangular piece on the shelf and the top is the cookplate.
If that's correct, how important do you think the thickness of the shelf is? Would it be possible do you think to make the shelf out of something like a kiln shelf? So thin and quick to heat up. As long as the afterburner is well insulated.
Also, the minimum depth of the topchamber is 4cm but the rest of the chamber is 4cm plus the height of the triangular piece?
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Post by Vortex on Apr 26, 2020 10:27:17 GMT -8
The shelf thickness is only limited by how insulated you want the roof of the afterburner to be, but the more insulated it is the hotter the afterburner gets and the better it runs. Here's an updated drawing of how the core is now. Exit port is the 230mm x 40mm gap, which is 3" / 75mm back from the front edge of the top of the shelf. Top chamber exits rear left.   EDIT: Added Side View image to show top chamber clearer. |
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Post by fishalive12345 on Apr 27, 2020 3:35:34 GMT -8
Thanks for the drawing.
The wider top chamber makes supporting and adjusting the shelf easy
Sorry, in my previous post I meant that I had just come to realise that the roof of the top chamber, not the afterburner, is the underside of the hotplate.
I'm planning to have a black oven immediately downstream of the top chamber so using ceramic fibre for the shelf in direct contact with the flame is a no no. Perhaps ceramic fibre sandwiched between ceramic glass and a kiln shelf.
Anyway, when (if) it gets built it should be possible to measure the temperature in the afterburner to have some idea of how it's doing.
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Post by fishalive12345 on Apr 27, 2020 4:21:43 GMT -8
Are there any of your dimensions that you would advise against scaling down? Not looking for a definitive answer but for sure your informed guess will be a very useful starting point.
Your system is, if I remember correctly, 6" or 150mm. I am working on plans for a 130mm system and have scaled down the firebox and port. I cast these last year but never got around to finalising the afterburner and top chamber as I wasn't sure what materials to use.
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Post by Vortex on Apr 27, 2020 14:36:47 GMT -8
I think ceramic fibre sandwiched between ceramic glass or kiln shelves would be ideal for the top of the afterburner. The sides also need to be made of an insulating material. I used IFB with ceramic fiber behind. IFB seems good, ideally I think you want a material that is highly insulating but with a little mass, so it will absorb some heat and glow red hot and radiate back into the afterburner.
Mine is a 6" / 150mm system. Temperature of the afterburner usually runs around 850C, but has gone up as high as 975C at times. That might be lower in a scaled down version. I haven't got around to trying out any other sizes yet. I would start out by scaling everything equally and see how it goes.
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Post by Jura on Apr 27, 2020 15:01:33 GMT -8
The shelf thickness is only limited by how insulated you want the roof of the afterburner to be, but the more insulated it is the hotter the afterburner gets and the better it runs. Am I seeing it properly? I can see there is sth. wrong with my dimensioning of the top chamber  |
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Post by Vortex on Apr 28, 2020 3:39:49 GMT -8
I'm not sure what you mean, can you be more specific?
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Post by Jura on Apr 28, 2020 12:04:33 GMT -8
Sorry ...Seems I was tired while posting .. I can not figure out whats the distance from the top chamber floor to the cook plate in your case.
And what's the size of exit gap from the top chamber to the left.
Can you see any mistakes in my sketch?
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Post by Vortex on Apr 28, 2020 14:38:22 GMT -8
It's a perspective drawing so maybe that is confusing you? The hotplate is the top of the drawing, distance from the top chamber floor to the underside of the hotplate is 3" / 75mm. The top chamber exit rear left is 184mm x 75mm. Here's a quick side view drawing which hopefully will make it clearer: |
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Post by Jura on Apr 29, 2020 12:18:29 GMT -8
It's a perspective drawing so maybe that is confusing you? The hotplate is the top of the drawing, distance from the top chamber floor to the underside of the hotplate is 3" / 75mm. The top chamber exit rear left is 184mm x 75mm. The only thing that confused me in you drawing was the total thickness of the afterburner ceiling and its insulation and how much room was left between the hot plate and the upper surface of the afterburner insulation. I remember you mention to have used CFB, so I drew it 3cm thick, and another 3 cm for insulation. Then the space left seemed to small to me. Am I getting it right or I'm mistaking sth. ? Were you able to see the sketch I posted ? I was sure it was visible as entered the post from another machine and in incognito mode. But today the image was not visible (icon of a blind target was displayed) |
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Post by Vortex on Apr 29, 2020 13:15:23 GMT -8
Sorry Rafał, I couldn't see your sketch before. I didn't even realise you had tried to post one, your comments make sense now. I didn't include a thickness for the afterburner shelf in my drawing, as I'd said above: My shelf is made of 1" / 25mm CF Board with 1" / 25mm CF Blanket on top, so total 2" / 50mm. The gap between the top of the blanket and the underside of the hotplate is about 3" / 75mm. The exit port is made of one of the old triangular pieces from the corners of the afterburner sat on top of the shelf, 3" / 75mm back from the front edge. The inside of the top chamber is 18" / 458mm deep, 2" / 50mm deeper than the firebox and afterburner, (as in my sketch above). This picture of the top chamber is easier to see. (The triangle piece was nearer the front of the shelf and the full width in that test.)  Hope that is clearer. |
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Post by fishalive12345 on Apr 30, 2020 5:46:48 GMT -8
Thanks Trev and Rafal for the pics and dimensions.
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Post by fishalive12345 on May 3, 2020 22:48:20 GMT -8
Hi Trev,
I'm thinking about how much control it's possible to have over the hot plate.
As I'm scaling down your dimensions to fit a 130mm chimney I plan to have a 40mm thick shelf and and a 60mm depth of the top chamber and then to adjust the height of the restriction to achieve the most balanced burn. I'm assuming that it's also possible to adjust the depth of the top chamber in order to tune the heating of the top plate. Does that sound reasonable?
Which are the hottest areas of the hotplate, above and in front of the exit port? How hot do these and other areas get? Is it possible to place pans in different positions for simmering for example? How long does it take to boil water? Can you use two pans at the same time? How long does the hotplate stay hot for?
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