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Post by peterberg on Feb 10, 2022 11:46:19 GMT -8
The core is on top of an air box, the inlet is from under the stove. As you already guessed, the same door frame could have the opening in front. Along the lines of the test unit, although it's separated from the door now but there's space available.
Where exactly the air is entering in the bottom door frame isn't really important, it could also be from behind.
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Post by scottiniowa on Feb 11, 2022 7:56:15 GMT -8
I would be curious if anyone has taken the above file (assembly of excellent components) and redone an assembly in SolidWorks 16 or older. Nothing against the Sketch up software, but I have 22 years with SolidWorks, and am more familiar with how the assembly parts of the software work. Just curious.. |
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Post by josephcrawley on Feb 11, 2022 8:27:26 GMT -8
I would be curious if anyone has taken the above file (assembly of excellent components) and redone an assembly in SolidWorks 16 or older. Nothing against the Sketch up software, but I have 22 years with SolidWorks, and am more familiar with how the assembly parts of the software work. Just curious.. Maybe just maybe this will work and save you a redraw grabcad.com/tutorials/tutorial-how-to-import-sketchup-files-to-solidworks |
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Post by scottiniowa on Feb 12, 2022 7:05:19 GMT -8
I would be curious if anyone has taken the above file (assembly of excellent components) and redone an assembly in SolidWorks 16 or older. Nothing against the Sketch up software, but I have 22 years with SolidWorks, and am more familiar with how the assembly parts of the software work. Just curious.. Maybe just maybe this will work and save you a redraw grabcad.com/tutorials/tutorial-how-to-import-sketchup-files-to-solidworksTried this a bit, and I presume I need "Sketch UP PRO" to export as you suggest in your tutorial? As that is one of the first things to do, under export, but my "free version of Sketchup, does not have such export function that I can tell. If I am wrong, please do tell. Thanks in advance. |
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Post by josephcrawley on Feb 12, 2022 9:27:10 GMT -8
Free SketchUp can export .dae files aka collada which solidworks supposedly can import.
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Post by grootebeer on Feb 21, 2022 6:51:05 GMT -8
The past months I have been busy with designing a complete stove for a one-man-band. And last but not least: I am working on updating the batchrocket website with the DSR cores. Dutch first, then English and subsequently other languages. This prompted two questions: - how well does the power of the stove conform to the relationships given by Yasin's spreadsheet? Specifically, do you know if the spreadsheet is still useful considering the configuration changes that have occurred since the earlier batchrockets were evaluated? - How are the updates to the batchrockets website coming along? May I also add my admiration for the work you do, the generosity with which you share the fruit thereof, and your helpful advice in general. |
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Post by peterberg on Feb 21, 2022 12:20:55 GMT -8
- how well does the power of the stove conform to the relationships given by Yasin's spreadsheet? Specifically, do you know if the spreadsheet is still useful considering the configuration changes that have occurred since the earlier batchrockets were evaluated? At the moment it seems that the power delivered is a bit lower than the plain vanilla batchrockets. - How are the updates to the batchrockets website coming along? The updates are on the back burner (pun intended) for some time now. The final DSR3 prototype will be arriving in parts and need to be assembled and tested first. When that's done with good results the official certification test is next. It might be late spring or even summer that I am able to dedicate some commitment to the website. May I also add my admiration for the work you do, the generosity with which you share the fruit thereof, and your helpful advice in general. Thank you, greatly appreciated. Honestly! |
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Post by grootebeer on Feb 21, 2022 14:26:29 GMT -8
Thanks Peter.
It seems that my question about Yasin's spreadsheet was a bit silly. I took a look at his formula and he uses a fixed factor of 3.7kw/kg. That is close to the figure I have for an average of a number of hardwoods at 80% efficiency. So, I think my question really comes down to what efficiency you are getting from the latest configuration.
I will wait for that until your DSR3 is certified.
Edit:
Of course, energy is power expended over time, but Yasin assumes a 24 hour period for each postulated load. Somewhere I got the impression from your writings that the your DSR 2 was consuming a load in 20 to 30 minutes. So I have based my designs for a stove, based on the earlier vortex, on that plus the 3.7kw.kg figure. The far more difficult problem is to estimate temperature profiles over time based on:
- the energy balance between source and sink while the load is under combustion,
- followed by the heat balance after combustion ceases,
- while estimating environmental factors such as surface convection, radiation, heat transfer rates in the stove media vs the surroundings, etc. etc ad infinitum.
I can see why traditional iron stove manufacturers just publish a kw or btu figure for a maximum load of kiln dried something or other.
That was my long way of getting around to saying that I shall look forward to your DSR 3 efficiency, kw and burn rate, whatever they may be.
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mac84
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Post by mac84 on Mar 2, 2022 11:55:58 GMT -8
To round off, not only the proportions of the parts are important, also the open spaces. In short: the port is 50% system size and proportions 1 to 4, the tube's inside is 100% system size or slightly bigger, the space around the tube is 150% of system size and the exhaust of the core is system size again in the shape of a slit.
Hey Peter,
I love the stove and appreciate all the work you put into it. I have followed along on all the development, but I have been waiting for a sketchup to figure out one thing that was not adding up to me.
With regards to the space around the afterburner tube, some quick math tells me that the cross section will be over 187% of system size. I took dimensions from the sketchup, and here are my calculations.
Upper box section CSA = 6.875 x 10.25 = 70.47 in^2
Tube section outside CSA = (6.375^2 x pi)/4 = 31.92 in^2
So take the tube area away from the box area and:
Box CSA - Tube CSA = 70.47 - 31.92 = 38.55 in^2
System size CSA = 130mm = 5.12in = (5.12^2 x pi)/4 = 20.59 in^2
So the percent of system size = 38.55 / 20.59 * 100 = 187%
It would be actually a little more since the tube is sunk in the floor of the upper box a bit.
If I am missing something, please let me know, but I was scratching my head over that area, so thought others may be as well.
Thanks, and again, great work. I hope to build a scaled version of this stove in the future, so I want to make sure everything is exactly to scale.
Edit: I drew it up in a CAD program and the actual CSA is nearly 194% of system size.
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Post by peterberg on Mar 4, 2022 8:08:34 GMT -8
Hi Mac,
My calculations are a little bit different. To begin with, the development model's ratio in the top box were a tad short of 1.6 to begin with.
Due to being used to ISO measurements and using other thickness of the thinnest oven shelfs (10 mm vs 1/2") I found some small discrepancies. Between the published cores done in inches and mm's, that is.
In general, I don't do surface or volume calculations by hand but leave that to SketchUp instead. I draw rectangles and circles by turn, select those one at the time and let SK do the calculations, shown in the Entity Info window.
The rectangle shape of the top box, omitting the little step in the mid front, came back as 70.1088 sq.". The outer circle of the tube, minus the same step, was calculated as 30.1179sq.". Subtracting the tube from the rectangle, the open space around the tube came down to 39.9909sq".
The inner cross section area of the tube was shown as 23.5888sq". So the ratio between open space and inner tube csa appears to be 1.6953342, a bit short of 1.7 then.
To see what the discrepancies were, I did the same with the drawing in metrics and that came out as 1.6388958 ratio.
Nothing shocking so far, I am in the dark how your calculations are so far off from mine.
edit:
It might has to do something with the calculation of the inner tube. I was aiming for a 130 mm (5.12") internal diameter but the smallest of this quality turned out to be 140 mm (5.51"). I was calculating the drawing, not the theoretical figures, could that explain the difference?
By the way, there appeared not much difference between a slightly narrower or wider tube in the development model. Anything between 4.92" and 5.91" seemed to work grossly the same. Now I come to think about it, the wider ones seemed to be a bit more forgiving.
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mac84
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Post by mac84 on Mar 4, 2022 10:53:45 GMT -8
I am not well versed on sketchup, so I was just using the fractional measurements it was defaulted to, so there is definitely some rounding error going to the nearest 1/16th of an inch. It seems most of our numbers are relatively close.
You are correct that the big difference is that I took the percent difference from the system size of 130mm and not the inner area of the tube. If I take the difference using the inner tube diameter of 5.51", then I get the same results as you within some margin.
So should one shoot for afterburner tube to be 115% of system size, and the space around the afterburner tube be around %170 of the tube CSA?
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Post by peterberg on Mar 5, 2022 7:51:13 GMT -8
So should one shoot for afterburner tube to be 115% of system size, and the space around the afterburner tube be around %170 of the tube CSA? Not sure about that. Let me explain: the difference between the prototype and the development model is marginal, in my view. But still, it doesn't run in the same way as the zero model. There are more differences, like the firebox which is somewhat wider and insulated(!) and more space under the fuel. Every refill to date bursts into flame very violently and the glowing phase is markedly longer. Since the EU certification test ends when the CO² is 4% (or 25% of its highest level), the average CO it brings on the diagram during tailout is quite high. If only it would be allowed to adjust the air supply once during the test this issue could be resolved. Shutting down the air supply completely when in full coaling phase means the CO goes down real sharply, reaching down CO² to 4% would be easily done in a few minutes instead of half an hour. That would leave some coals in the firebox, as it is now it will all go down to ashes when left alone with the air inlet open. On the other hand, the prototype tended to be much slower to come to full operation when started cold. This has been solved by grinding a vertical slit in the internal chimney pipe. High in the bell, so at first most of the produced heat is escaping that route, heating up the chimney first. Later in the burn the produced volume of hot gases is much greater, this is choosing the longer route to the bottom of the bell instead. This "permanent bypass" is only 5% of system csa, a slit of 100x6 mm. Which in imperial this is 3.94" by 0.236". During the past week I also made the end port narrower, 82% instead of the 100% in the zero model. This seems to diminish the over-enthousiastic burns somewhat. During such a burn the top window went completely opaque. Bottom line: nothing is engraved in stone yet, time-to-market will be quite some way off, as are the final parameters for the open source design. |
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Post by grootebeer on Mar 7, 2022 3:55:04 GMT -8
Peter or anyone reading, do you have a link for the EU Certification test protocol? I did some searches and the standard seems to be EN 13240. I also found BS EN 13240 where they only want EUR 335.24 for a pdf! All I want is know what the protocol is so that I can try to follow it myself - the standards that have to be met are pretty much open source. I did find a 2001 draft at MHA.NET.ORG which is helpful, but seems outdated looking at the dates. Does anyone have a less expensive source or a better idea on how to go about prepping for a test? |
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sertus
New Member
Plato is dear to me, but truth is even dearer to me!
Posts: 20
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Post by sertus on Mar 13, 2022 0:52:30 GMT -8
bds-bg.org/bg/project/show/bds:proj:89094 - in Bulgaria, the latest operating standard is - BDS EN 16510-1: 2018, which is aroud EUR 120 for a PDF. I hope this will be of help. If you go to the link above you can translate it with Google and get the copy in an English language as well.
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Post by grootebeer on Mar 30, 2022 7:09:51 GMT -8
Thank you sertus - that worked fine.
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