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Post by Vortex on Jan 29, 2019 3:01:25 GMT -8
Bob's your uncle? Is that a Dutch saying, Peter? https://en.wikipedia.org/wiki/Bob's_your_uncle"Bob's your auntie" seems to be more common these days  |
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Post by ronyon on Feb 1, 2019 18:12:51 GMT -8
Some batch box designs feature a firebox with a steel or glass top.
Can the separation between the firebox and top box be made with these materials?
What about the top of the topbox, can that be made of steel or glass?
More broadly, it is said that a batchbox doesnt have to have insulation around the firebox.
Is the same true for a DSR2?
What about the topbox on a DSR2?
Does that need to be insulated?
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Post by satamax on Feb 2, 2019 0:00:28 GMT -8
Basically, the steel plate you would put between fire box and top box is "insulated" and would die in a short time.
The bottom, back and sides of my batchbox are still insulated a smidge. With 6cm Ytong.
Topbox on a DSR3 has to be insulated imho. Except in the case of a cooking DSR2, where it's top is metal or glass. But that has a tradeof in efficiency most certainly.
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Post by peterberg on Feb 2, 2019 1:49:09 GMT -8
It greatly depends on what is expected of the heater. In case cooking on top is required glass would be best. That's different from the viewpoint of an oven in the top box. In that case the entire box, floor as well, need to be of accumulating material. Combination of a cooktop and oven is also possible, another switchback could be introduced so from bottom to top you'll get firebox, top box slash oven and cooking on the third level.
A couple of days ago I raked all my courage together, plucked myself out of the comfy chair and started hacking into the DSR2 model in my workshop. It's now amended in such a way that the top box is protuding out of the barrel(s) above the firebox. With a makeshift glass door so it's visible what happens inside. Even baking something small is possible now although there isn't any accumulating stuff in the top box. The view of this altered core running full tilt is quite spectacular to say the least! I'm not entirely happy with the results of the single testrun I carried out. Not sure what caused a short overfuel situation, whether it's the configuration of the end port or the air inlet. I'll run a couple more testruns this weekend and I'll post the results in due course.
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Post by satamax on Feb 2, 2019 4:31:40 GMT -8
Peter, i can't remember, you have top port in that one, or back port and top box?
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Post by Vortex on Feb 2, 2019 5:05:39 GMT -8
Glad to hear you're working on the DSR2 again. Over-fueling in my setup I look for either too large an exit from the top chamber or too little primary air, or a combination of both. I don't have that large secondary air inlet in the rear of the port though, so I would probably also try reducing the secondary and increasing the primary.
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Post by peterberg on Feb 2, 2019 5:34:35 GMT -8
Peter, i can't remember, you have top port in that one, or back port and top box? Back port and top box. As such the bottom half is very much like the Mallorca build, top box as the last one which was yielding the best results so far. |
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Post by peterberg on Feb 2, 2019 5:55:36 GMT -8
Glad to hear you're working on the DSR2 again. Over-fueling in my setup I look for either too large an exit from the top chamber or too little primary air, or a combination of both. I don't have that large secondary air inlet in the rear of the port though, so I would probably also try reducing the secondary and increasing the primary. I'm inclined to think it's a little bit different in this setup. The end port is now at 82x140 mm which is about the same as a round 120 mm riser. But this one sports a square riser so this port is 79% of the riser's csa. Looking at it, the firebox eyed as being fed by lots of primary air. At this time I tend to think about pressure differences more than openings. Viewed from this angle, the firebox has an opening at atmospheric pressure and one at under-pressure. So air tend to rush through when draft is ramping up. The port is amplifying the draft of the chimney so to speak. Now looking at the top box, seen in stream direction the exhaust opening is smaller than the feed opening (the riser) so gases tend to rush through again, amplifying draft even more. This situation is seen only with a full load running at full bore, half loads are behaving admirably. For next test I'll widen the end port so pressure difference will be hopefully much smaller. When this won't work I'll make the primary air inlet smaller for another test so production of conbustible gases would be lower. I'd browse through my test results so far and a larger end port seemed to suppress the CO peak at the start as well. We'll see what turns out being the best and if not, digging deeper is in order. |
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Post by satamax on Feb 2, 2019 7:29:22 GMT -8
Peter, would you dare to fit a metal plate as the ceiling of the shoebox? Or would you wait until later in the gases path?
I'm talking with Isch, about the next range retrofit.
I guess the next one will be a mixture of my workshop heater, and a range. Using the oven door as the firebox door. And having the oven in an adjacent metal and brick bell. Or may be if the range is big enough, with two ovens, it could be all in one unit.
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Post by DCish on Feb 2, 2019 7:36:28 GMT -8
Watching this thread with interest! |
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Post by stefanvh on Feb 4, 2019 1:43:32 GMT -8
Hi Stefan, welcome to the boards. Is there a design of the DSR2 'ready for production'? I am looking to build a rocket mass heater and this new design looks really promising. Or would you advise to stick to a batch rocket design for now? The principals of the design are fixed, I fully expect it to be as scalable as the straight batch box or sidewinder. Just take the size of batchrocket you need for your application. Replace the riser above the top of the firebox with a top box as wide and high inside as the width of the firebox. Opening on top the same csa as the riser stub and bob's your uncle. The top box is meant as a replacement for that high riser, in most circumstances it's also usable as an oven. Thanks Peter.
So the DSR2 design is actually a simple but great modification of the batch rocket. I like it . i will have to do some more research on the exact dimensions etc. for myself. The idea is to combine it with a bell/oven and to heat the water of the central heating system. Obviously the latter requires some extra thinking to prevent the infamous boom-squish.
I will probably make a build log here, but I am not sure yet when we will get started.
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Post by peterberg on Feb 4, 2019 9:34:11 GMT -8
I will probably make a build log here, but I am not sure yet when we will get started. When you do, please start a new thread. |
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Post by ronyon on Feb 4, 2019 21:29:11 GMT -8
DSR2 needs some certain volume in the topbox to operate properly.
If we use the topbox as an oven,wouldnt the items cooked mess with the airflow,etc?
I'm asking specificy because I'd like to use the topbox oven to "bake" wood in a retort, feeding the woodgas back into the firebox.
I'm imagining that oven use is expected to be intermittent, and therefor not a concern to performance.
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Post by peterberg on Feb 5, 2019 1:36:15 GMT -8
DSR2 needs some certain volume in the topbox to operate properly. If we use the topbox as an oven,wouldnt the items cooked mess with the airflow,etc? As I see how the flames stream through the box, I would say the height at the back is crucial. Using that top box as an oven is the next step that's planned. Probably the object in the top box / oven shouldn't be longer and higher than half the relevant dimensions of the box, using a top/front exhaust opening. For now, I'm not satisfied with the results: in my configuration the chimney draw is ramping up during the course of a burn. I started with 0.09 mbar and ended up with 0.28 mbar, a threefold increase. My chimney is too good (probably also too large) and the exhaust gases are too hot so draft is an important factor. Most official test reports I've seen, mention a mean draw of 0.12 mbar +-0.02 (12 Pa) as being required. So today I've ordered a stainless steel draft limiter which is adjustable so I could pinpoint draft to a certain maximum. To be delivered in the course of this week. Yesterday night I tried half a load and that went very well, no overfuel with a CO line that stayed flat for more than half of the admittendly short burn of 30-ish minutes. As long as the fireball at the rear end of the box is transparent the Testo is extremely happy. The CO numbers won't go below 280 ppm which is very rare these days so hopefully that will be adressed next calibration. At first, the afterburner flames are confined to the riser stub, only now and then some flames peak out. Somewhere halfway in the run the fireball is raising slowly into the top box until it fills the rear half completely. Top box exit is the width of the box combined with the csa of the square riser. This opening is situated top front(ish), other exit ports at both sides are likely to follow later. This latter configuration is important for the construction of a cooking range, obviously. Interesting times, again. |
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Post by Vortex on Feb 5, 2019 4:34:56 GMT -8
Most official test reports I've seen, mention a mean draw of 0.12 mbar +-0.02 (12 Pa) as being required. So today I've ordered a stainless steel draft limiter which is adjustable so I could pinpoint draft to a certain maximum. To be delivered in the course of this week. I'm expecting the draught stabiliser I ordered to arrive in the next couple of days. Would be good if you could let us know how well yours works for you in the draught-stabiliser thread: donkey32.proboards.com/thread/3475/use-draught-stabiliser-regulator |
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