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Post by BenAlexanderT on Nov 21, 2019 3:36:53 GMT -8
Peter, do you think it would work to construct a 120-125mm core from 25mm thick insulating firebrick? Or would 25mm not provide enough insulation? (Clearly the riser would be thicker than 25mm -- more like 50mm) At the moment Peter is using, as far as i saw in the previous posts/pictures/sketches, 25mm insulation, only in the riser. The rest of the parts are refractory concrete casts. Basicly, somekind of non insulative mass and only the riser with an insulation.
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Post by peterberg on Nov 21, 2019 5:17:22 GMT -8
Peter, do you think it would work to construct a 120-125mm core from 25mm thick insulating firebrick? Or would 25mm not provide enough insulation? (Clearly the riser would be thicker than 25mm -- more like 50mm) Whether the insulation of 25 mm IFB would depend on the insulation value of that particular brick. Apart from that, I'd feel a 25 soft brick is far too prone to abrasion. Split firebrick on the inside and IFB on the outside would be a far better option in my view.
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Post by peterberg on Nov 21, 2019 5:25:55 GMT -8
Peter, do you think it would work to construct a 120-125mm core from 25mm thick insulating firebrick? Or would 25mm not provide enough insulation? (Clearly the riser would be thicker than 25mm -- more like 50mm) At the moment Peter is using, as far as i saw in the previous posts/pictures/sketches, 25mm insulation, only in the riser. The rest of the parts are refractory concrete casts. Basicly, somekind of non insulative mass and only the riser with an insulation. That refractory castable is actually insulative from a material perspective. Specific mass of this material is 1.92 kg/l as opposed to around 3.0 for ordinairy concrete. That said, it still holds too much mass for such a small core, this material applied to an 8" core would be much better. The whole idea of insulation in the afterburner only is the fact that the pyrolysis stage doesn't need to be overly hot. Rather the contrary, keeping the core below a certain temperature threshold means it won't overfuel that easily.
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Post by BenAlexanderT on Nov 21, 2019 6:08:13 GMT -8
At the moment Peter is using, as far as i saw in the previous posts/pictures/sketches, 25mm insulation, only in the riser. The rest of the parts are refractory concrete casts. Basicly, somekind of non insulative mass and only the riser with an insulation. The whole idea of insulation in the afterburner only is the fact that the pyrolysis stage doesn't need to be overly hot. Rather the contrary, keeping the core below a certain temperature threshold means it won't overfuel that easily. So, that means that a little mass is actually better, in order to have a more stable burn?
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Post by peterberg on Nov 21, 2019 8:35:59 GMT -8
So, that means that a little mass is actually better, in order to have a more stable burn? That's the general idea, yes.
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Post by smartliketruck on Nov 21, 2019 19:23:51 GMT -8
Is there any design changes to carry over from a shoebox riser to a regular vertical riser batch box so that it would also be able to run as an open system without a secondary air channel?
I did in the past play with a shorter riser that had equal or slightly more volume than a standard calculated/scaled regular vertical batch box that seemed to run well based on sight and smell of exhaust. If I remember correctly I only restricted the riser back down to system size. I don't recall trying to run it as an open system without a secondary air channel.
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Post by peterberg on Nov 24, 2019 2:05:06 GMT -8
Is there any design changes to carry over from a shoebox riser to a regular vertical riser batch box so that it would also be able to run as an open system without a secondary air channel? Now I come to think about it: one of the features that made the DSR2 behave itself is the end port, being 5% larger csa as compared to the riser port. What normally happens with an open standard batchrocket system is that the flames are rising out of the riser. This isn't a good sign, very spectacular but undesirable from a combustion point of view. It might be that such a restriction at the end of the riser could have the same effect of confining the afterburner flames in the riser and limit the maximum burn rate. But this is just an idea, it might work or not. Need to be tested before it could be accepted as a working solution. I would combine it with a square riser without a back sweep on the riser's floor, i.e. the simple riser layout. Question is open whether it should be a round, square or rectangular opening, like the one in the DSR2.
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Post by josephcrawley on Dec 9, 2019 20:50:09 GMT -8
Peter is there a side winder version of the DSR2 in the works? Thanks for all the work you do!
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Post by peterberg on Dec 10, 2019 1:15:49 GMT -8
No sidewinder version DSR2 in the planning, sorry. In my view, having the top box turned 90 degrees and everything else equal won't create an advantage, rather the opposite. Having the riser stub to the side and the top box across the firebox doesn't create enough space either, so the top box will stick out at the other side. The beauty of the DSR2 as it is lies in the simplicity of it all, really easy to build. That would be thrown to the side (pun intended) with a sidewinder version.
That's not to say I couldn't work out what the consequences would be and give it a thought whether or not it's worthwhile to do the development all over again. I am not getting younger you know, I will be 74 years old within 12 weeks from now, give or take some days.
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Post by scottiniowa on Dec 14, 2019 11:01:44 GMT -8
The question was posed to me, and I think this has been talked about a bit but wasn't for sure the constraints. And I'm thinking this would only really work with a cast unit as the fire brick would self-impose constraints due to brick thickness and size (less actual cutting)
So the question came up, if we have a 6" size or any other size that was done/sized right, (working well) and we just want 10% larger, or 20-30% up/down with our modern technology in CAD, this is fairly easy to do, with a piece drawn, you can increase or decrease the size what ever percent you want. That being said, are there certain things (areas or thickness or openings) that DO NOT lend them selves to simple enlargement in all directions. For the stove to work well. (understanding that the flue can handle the size we propose to make the new stove)
And to to make sure to let you know what I am talking about, was this DSR2 in the open format. I guess to kind of go with this, if you increase size 10% of the burn unit, would the mass required to store/collect also go up about the same..(assuming that you had it about the way you wanted it) for the actual room, any barrel exposed surface would stay the same, only heat storing mass is in question. This is a pretty open ended question, and doesn't matter so much if it is a very subjective to the situation, I certainly understand this. It was the above stove sizing question most pondered.
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grga
Junior Member
Posts: 76
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Post by grga on Dec 16, 2019 7:40:09 GMT -8
Very impressive ideas and development! – It has been more than a year since my previous visit… I am running at home the original Peters straight Batch box design (18cm riser) for the third year now every day in winter - and I love it each day more. May be after a few years that I would need to rebuild/change to a new core… - this DSR2 seams a good choice.
What are the main benefits of this double shoebox regarding to the straight design: - It has black oven available in the design, which offers extra fun at observing fire. - It does not require riser? - Does it has better efficiency? - Can it be used in a bell similarly as the straight version? - I have read that it is even simpler to operate – less or no air adjustment? -
It requires similar space in the bell (the floor plan) as the regular version- previous version (cca. last year) took less space…
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Post by martyn on Dec 16, 2019 11:18:15 GMT -8
I like your post grga, unfortunately I have never been able to upload many of the diagrams and I must of missed the basic concept of how it all works. Sure I can see how to build one but I don’t know why it works so well with such a short riser?
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Post by wisc0james on Dec 16, 2019 14:30:45 GMT -8
I think the top shoebox acts as part of the riser as well.
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Post by esbjornaneer on Dec 26, 2019 1:02:39 GMT -8
Hi Travis, the firebox and port are in fact like the normal standard one. The riser is square instead of octagon or round but still the standard size. So one side of the square is the same figure as the diameter of a round one according to the calculator. The end port (to the bell) is 6% larger as compared to the first and as wide as the top box, that's all. Beware though, the placement of this port and the ridge at the ceiling are critical. Edit: Funny thing is, ashes that settle down in the top box show an empty patch right beneath the end port. Indicating a higher air velocity over that particular spot. It emerged since the ceiling ridge moved to its current location. Hi peterberg and Jura, I just came across this comment about port placement being critical. If your latest statement is more true than this please remove this post.
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Post by peterberg on Dec 26, 2019 2:17:52 GMT -8
Hi Travis, the firebox and port are in fact like the normal standard one. The riser is square instead of octagon or round but still the standard size. So one side of the square is the same figure as the diameter of a round one according to the calculator. The end port (to the bell) is 6% larger as compared to the first and as wide as the top box, that's all. Beware though, the placement of this port and the ridge at the ceiling are critical. Edit: Funny thing is, ashes that settle down in the top box show an empty patch right beneath the end port. Indicating a higher air velocity over that particular spot. It emerged since the ceiling ridge moved to its current location. Hi peterberg and Jura , I just came across this comment about port placement being critical. If your latest statement is more true than this please remove this post. Sigh... Port placement is still being critical in the sense of placed on top, as a slit as wide as the top box and a certain proportional distance from the riser. Maybe I should refrase it this way: in case the top box is shorter than the firebox, the end port and stumbler, if possible, should still be situated as if the top box was at full length. Is this easier to comprehend? I always try to formulate as precise as I can, although English is my second language and self-taught. My goal is to provide a set of rules which will result in a working combustion core when applied correctly. But... this set of rules is not designed to cater for each and every variant that anybody might come up with. So when asked for, I do suggestions for what I think would lead to a proper working device. Nothing less, nothing more. When you have the choice, just follow the recommendations. Since the workings of this device are based on laws of physics it'll work like a tested and approved one when built this way. The greater the deviation away from the tested development model the higher uncertainty will be whether or not it will work as promised.
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