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Post by peterberg on Nov 11, 2011 11:00:59 GMT -8
Peter, do you think that the down-hanging plate can be (made into) a trip-wire of sorts too? Impossible to say at the moment. The wire need to be not very close to the 2nd air inlet. Maybe when the plate had a fourth wall, on the side of the tunnel, that could be bent into the tunnel and form the wire about 2" to 4" from the feed. Can be done by a craftsman with appropriate tools, although I would think it's a bit complicated. I am currently helping to build a rocket stove not too far from here, I've included your idea with the brick in an 8 inch rocket stove. It's placed 3rd in a 4 and-a-half brick burn tunnel (counting from the feed box). NIce to hear, but why the 3rd brick? In that way, the distance from the feed to the trip wire can be as long as 7 inches. Closer to the feed, like 4" would be better, to my opinion. Either way, it would be very interesting what the results will be! |
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hpmer
Full Member
Posts: 240
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Post by hpmer on Nov 12, 2011 12:16:23 GMT -8
I was very intrigued by the secondary air idea but, not having a spare metal tank nor anvil handy, decided to try it with copper pipe. I have a rocket stove, not a heater, so I can easily see the effects of changes in the exhaust.
My stove has been pretty good with only very minimal smoke occasionally, but the secondary air seems to have completely solved that issue. The only problem was the copper pipe deformed to an oval in the burn tunnel so I may have to encase it in some sort of insulative mix.
The pipe serves the same purpose in holding the wood away from the bricks with a top horizontal piece, then turns down to run along the vertical sides before turning into the burn tunnel. So it provides cool air up top that is presumably heated somewhat by the end. All in all, a noticeable improvement.
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Post by peterberg on Nov 13, 2011 8:38:33 GMT -8
I was very intrigued by the secondary air idea but, not having a spare metal tank nor anvil handy, decided to try it with copper pipe. I have a rocket stove, not a heater, so I can easily see the effects of changes in the exhaust. You provided the extra air at the right spot with other means, could be done, of course. What it won't do is the function of little overhang of the plate and the as yet unproven feature of minimizing fire creeping up. But oh well, it's funny that you are able to confirm the effect of the air inlet at that spot, thank you. |
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Post by Donkey on Dec 2, 2011 16:54:28 GMT -8
I'll be running this stove in it's current configuration off and on for the next few days.. I'll watch it and report. Ok.. I've been running the stove with the plate in since Oct. 21 and I'm impressed. The stove starts right up, gets to efficient working temperature in short order and chugs away very cleanly right up to the end. I've only seen the fire creep up (and only just a little) once, where after two showers (by the kids), I wanted a bath. The firebox was loaded 4 times, back to back. My guess on why the burn-back seems obvious.. One issue. Just two days ago, I noticed that it wasn't working quite up to snuff, I could smell a difference in the fire. On inspection, I found that the bottom of the metal plate had heat warped. The metal had bent till it was almost touching the bricks (in front). The solution, bang it straight again on the anvil. |
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Post by peterberg on Dec 4, 2011 2:19:01 GMT -8
@donkey,
It's very pleasurable to read your comment about the plate being warped. Especially the fact that you were able to tell the difference between running with or without a proper 2d stream plate.
Maybe it's time for someone to come up with a proper name for it, christening it as it were...
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Post by Donkey on Dec 4, 2011 10:44:26 GMT -8
Well.. It's YOUR gizmo.. Seems that you've already suggested a name (of sorts), that is "stream plate". Not THE most attractive term..
Perhaps you know of or can think of a better one?
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Post by canyon on Dec 7, 2011 1:18:36 GMT -8
Call it the "Peter Plate" !  |
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Post by Donkey on Dec 7, 2011 9:24:03 GMT -8
'Course, it might be accomplished in a different way, without a "plate".. So it could be called the "Peter Channel"  |
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Post by peterberg on Dec 9, 2011 6:36:44 GMT -8
'Course, it might be accomplished in a different way, without a "plate".. So it could be called the "Peter Channel" Hihihihihi... ;D If this gizmo became widely known by this name, I would be very honored. ;D |
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Post by Donkey on Dec 9, 2011 11:17:52 GMT -8
Well alrighty then..  I plan to make a Peter Channel for the stove in my mud hut. I've repaired it and now it works well enough for the tiny little building that it's in. It is a 6 inch stove with a relatively short bench run, though there are two chambers within the bench that seem to act a bit like bells (though they were not built to BE bells), consequently, the exhaust temperature is surprisingly low. This stove is built into a pretty small space, in order to get the stove in and leave enough space inside the building, the tolerances in the stove itself are very narrow. The barrel is a used 16 gallon gear oil drum and the heat riser jacket inside is quite "tight" to the airflow. In order to get enough flow through the bottom manifold, originally I set the barrel on next to nothing with a wide, concavely carved space below. The barrel was setting precariously up there and one day, I bumped it a little and it broke loose. To fix it, I've spot welded on a brim, like the brim of a hat to give footing and hold up the drum. This allowed me to carve out the manifold below and improve the stove greatly. I like to be able to get my arm inside these stove to make them easier to clean, so I usually make the feed opening longer and consequently narrower, while maintaining something close to a system size cross sectional area. The feed opening is 4.75 inches wide by 6.75 inches long, which has an opening area of about 32 square inches. System size is 28.26 square inches, my opening is technically a bit too big, though it's within what I consider to be reasonable tolerance. The system is not a "racer", it's more of a slow plugger and does occasionally smoke back. It needs more baby-sitting than I would like. My hope is that an appropriately designed Peter Channel will help. I figure that the plate (for the Peter Channel) should be 4.75" wide and the gap (created) should be somewhere between 5/16 (0.3125) and 7/16 ( 0.4375) of an inch. As before, I'll start a little big (around 0.5 inch) and work my way down. I have a question about the amount the plate needs to hang down. You mentioned before that it should be the same as the gap, though at one point you also told me I should leave the other one I built longer (too late). What are we really looking at as a proportion down there? How do I know what's too long and what's too short? |
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Post by peterberg on Dec 9, 2011 12:48:21 GMT -8
You mentioned before that it should be the same as the gap, though at one point you also told me I should leave the other one I built longer (too late). What are we really looking at as a proportion down there? How do I know what's too long and what's too short? OK, I've failed to explain why the overhang should be the same as the gap. That's the proportion I've got the best results with. The overhang shorter or non-existent, the channel won't draw as much air and the results where not as good. An overhang which happened to be twice as long resulted in a more aggressive draw and sometimes during the burn for a couple of seconds a sound like a steam whistle. Or maybe sometimes like a pipe organ, but producing a lot more overtones at the same time. Plain and simple a false note. Maybe it only worked this way because the whole J-tube was made out of steel tubing at the time. The Testo wasn't impressed at all by this and called it a mediocre test run. That occasion I was too late telling you to leave the plate longer, I was very curious you would experience the same not very musical serenade. In the end, the same measurement for the gap as the overhang would very likely be the best solution and at the same time very simple to communicate to other people. Let's call it the 5% rule with gap and overhang the same. Another question now I've come to think about it: I really don't know whether you should use 5% of system size or 5% of the feed tube c.s.a. since they are not the same. |
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Post by Donkey on Dec 9, 2011 22:20:15 GMT -8
The overhang shorter or non-existent, the channel won't draw as much air and the results where not as good. An overhang which happened to be twice as long resulted in a more aggressive draw and sometimes during the burn for a couple of seconds a sound like a steam whistle. Or maybe sometimes like a pipe organ, but producing a lot more overtones at the same time. Plain and simple a false note. Maybe it only worked this way because the whole J-tube was made out of steel tubing at the time. The Testo wasn't impressed at all by this and called it a mediocre test run. That occasion I was too late telling you to leave the plate longer, I was very curious you would experience the same not very musical serenade. Well, the material I'm using to build the plate(s) is from an old water tank, pulled from the dump so it's free and I've got quite a bit of it still.. So, I'll build it extra long and note the differences as I shorten it by increments. It is possible that the brick internals may have too much roughness, cause too much "noise" to allow for the same kind of tone(s) generated in your much smoother model. I'm intrigued by your results, have been thinking about harmonics, pulsings and flutterings that I've experienced in the past and wonder at what it all means and if it can be exploited to build a better stove. Maybe good enough, maybe there's something that can be gained in fine tuning.. I don't know. Let's find out.. ?? I've wondered the same thing. System size is a gap around .33 inches, intake size is .47. Somewhere in there is a sweet spot. |
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Post by Donkey on Dec 14, 2011 9:07:35 GMT -8
I've built and tested (briefly) a Peter-Channel for the little stove in the mud hut.
It has a gap of 7/16 of an inch and hangs down twice the length of the gap. The top sticks out above the brick 2 inches and has arms that the plate hangs on that stick out 2 inches on either side.
When I was making this one, I did a burn test when the gap was 1/2 an inch. The fire smoked a little and was slow to start, but once it got going it ran quickly. It raced and fluttered and wanted to smoke back from time to time.
The following day (yesterday) I took the plate down to it's present size (7/16) and it started right up, got up to temperature quickly and burned throughout just about as trouble-free as this stove has EVER been!
Ok, so Peter.. The plate hangs down 2 times the gap measurement. I'm not getting a "note" out of it, though it has a little pulse once the thing is up to heat. I'm a little reluctant to shorten the down-hang as the thing works pretty well right now, I'd hate to mess it up. Do you think there's a reasonable possibility that shortening it (gently) will make it perform better?
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Post by Donkey on Dec 14, 2011 9:11:50 GMT -8
On a side note.. Last night I took my youngest kid to play practice.. When we got home, I got out of the truck and smelled a whiff of smoke, fairly clean smoke but smoke nonetheless. I went to investigate and found that my wife had started the shower rocket but forgotten to put in the Peter Plate.. When the plate was slid in, the smell went away.
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Post by peterberg on Dec 14, 2011 12:17:05 GMT -8
Ok, so Peter.. The plate hangs down 2 times the gap measurement. I'm not getting a "note" out of it, though it has a little pulse once the thing is up to heat. I'm a little reluctant to shorten the down-hang as the thing works pretty well right now, I'd hate to mess it up. Do you think there's a reasonable possibility that shortening it (gently) will make it perform better? Donkey, the size of the overhang is less important compared to the gap. Nevertheless, the performance of the tiny stove I've done the testruns on has been consistently a little bit better with the smaller overhang. So, I'd think the longer down-hang doesn't bring any real improvement. There's another, maybe important point to make. Your mud hut stove is sporting a feed tube which happens to be 13.5% larger as system size. Maybe that's the reason why this stove has been a slow plugger before. Now with the peter channel it's running as a normal rocket. The channel itself is, even compared to the feed tube, at the larger side of things. To be precise, 6.5% of the feed tube, and about 7.5% of system size. The proportion to the feed tube is clearly more important. And the next thought is: with a feed tube of 50% too large and a channel to match that, would it still run as well? I'll have to try that some time. |
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