DSR1 +Vortex aspects, now DSR3

[peterberg]

Aug 21, 2021 22:40:37 GMT -8 smartliketruck said:

Jul 1, 2021 12:39:08 GMT -8 peterberg said:

 Still assuming this is a 130 mm (5.12") system, the ceramic tube is 115% of system size, the port 50%, the end port 100% and the total space around the tube 158%!

It is hard to tell from the pictures, is the end port in the front of the secondary burn chamber above the window, or is it in the back end above the ceramic tube?

The end port is in the back end above the tube, in the ceiling. So the required length of "riser" is to the front through the tube and folded back again around the tube.

It's interesting in the sense that the relative proportions of the second half versus the end port seems to be important. Namely 1.6 to 1 in this case, the last one being the system size. So the end port need to be preceded by a larger space, restriction of the end port is firmly tied to the size of the back fold, much less so to system size.

For example, when scaling down the back fold space the end port needed to be scaled down as well in order to achieve the same results. Although to date, the above proportions relative to system size worked best.

[peterberg]

The past months I have been busy with designing a complete stove for a one-man-band. The design is ready now, we are looking for ways to have one built in order to have it tested for EU certification. Of course I can't tell much about the innards of this particular stove, it's a a move away from slow-release mass heaters. Suitable for larger spaces, not just normal living room space. The development model is behaving itself, the materials of the top box are holding up well.


The chimney pipe is incorporated in the stove body, the core and door assembly are one unit that can be sled out of the body. Air inlet is through the bottom so air is extracted from floor level. This is done to make an outside air provision possible.
The core is resting on an "air box" which is equipped with an open/closed valve, operated from the front. The top box has a fixed window, there's no oven provision as in the DSR2.

Most of the core is done with ceramic kiln shelves insulated with superwool, so it's very low-weight. There's no separate secondary air provision as such, all air is fed in through the door frame. The slabs left and right are thought as some limited heat stockage. This might be soapstone or granite or whatever, no decision as yet.

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.

[grga]

I like the idea and it looks nice! What come to my mind is that the stove would for sure have high burning efficiency but the problem could be its energy efficiency? If I formulated it correctly. Since it seems to me that quite hot burned gasses would enter the chimney as there is quite small volume of the stove and the gas flow is quite fast. The exit temperature of gasses would probably be much higher than 100 °C, probably close to 200°C? In that respect it would be similar as regular metal fireplaces commercially available except that the efficiency of the burn will be higher. Maybe you plan some water exchanger and accumulation in separate water tank or floor heating to get the energy from the stove more efficiently. The granite slabs is more in function of decoration than real heat storage.

I like the performance of “slow-release” mass heater each year more (my build according to your plans) where in cca. 1 hour it accumulates the energy for releasing it nicely the whole day. If it would be a metal heater than it would be only awful heat radiation to the room during 1 hour of burn and some hour more.

[peterberg]

This DSR3 is a small stove, in the sense it's a 130 mm system. Although it looks like that, the gases aren't sent straight into the chimney. There's an internal exhaust pipe, behind the core. All the gases need to go down first, the exhaust opening is close to the floor.

Furthermore, such a system could theoretically serve a bell with an internal surface area of 3.3 m². To stay on the safe side, this bell is just a tad above 3 m². So it'll work on any chimney stack but the exhaust temperature is somewhat higher. Efficiency of a stove is combustion efficiency multiplied by extraction efficiency. In this case, according to the results of the development model, the overall efficiency would be above 90% at the least.

So this stove isn't, and isn't meant to be, a slow release heater. But on the other hand it won't be something that could drive a central heating system. It simply is a compact stove for heating of larger floor areas. The development model exhausted in the range of 150 ºC and that is half of what comparable steel box stoves tend to do. The production model is a little bit larger than the development model, I fully expect it to exhaust lower temperatures than the level you mentioned.

[Orange]

so this is an alternative to steel box stoves with 130mm exhaust. I'd love to se combustion efficiency compared between these because it's easy to extract heat and increase overall efficiency: donkey32.proboards.com/thread/3586/bb-box-stove

[martyn]

Peter are there any further developments ?

[peterberg]

Not as such Martyn, the first full prototype is planned to be produced from the middle of Januari onwards. The final drawings are 90% ready, the metal fabrication firm is chosen. The door assembly is done two months ago, once the body is done I need to hire a wet saw and buy a number of corderite oven shelves. Once assembling of the number one is complete I need to test whether or not it is doing what I think it should. When it is, it can be offered for testing in an accredited laboratory.

When all this is over and done the first series will be produced. Another 5 or 6 months away, judging by the slow movement so far.

[martyn]

Sounds good and all going forward …..

I dont know if this would work for you but I only recently discovered a water jet cutting facility quite near to my home, they cut metal and stone very accurately and pretty cheap.
I have taken in fire bricks to be cut into some curved shapes for an oven I am building, the cut edge finish is perfect.

[foxtatic]

Peter, I understand that you are trying to get this DSR3 complete stove design certified. But are you comfortable enough with the core that you can share the final dimensions of just that part with us?

I'd love to start tinkering with a stove design to contain the DSR3 core. My big 180mm DSR2 in the shop is great and I think it needs a more tame DSR3 little brother in the house

[peterberg]

Feb 3, 2022 10:08:20 GMT -8 foxtatic said:

Peter, I understand that you are trying to get this DSR3 complete stove design certified. But are you comfortable enough with the core that you can share the final dimensions of just that part with us?

I'd love to start tinkering with a stove design to contain the DSR3 core. My big 180mm DSR2 in the shop is great and I think it needs a more tame DSR3 little brother in the house

At the moment the first final design core isn't ready yet. The development model works as intended, no question about that. It won't go into overload mode due to a brake feature entirely done by proportions and as such completely automatic. But... it is only tested in my workshop, using my chimney and my fuel.

Having said that, you can have the drawing, no problem. Mark that this build is done with thin (1/2") ceramic kiln shelves and 1" Superwool around the entire core. This is meant to be built into a steel container in order to hold it all together. The circular tube that's in there can be mimicked with 1" Superwool inside a steel stove pipe, exactly like the 5-minutes riser. The open end of the port should be fixed in some way because the steel tend to disform quite a bit without it. The Superwool will get red hot at the back end every burn, as is the steel pipe. For this reason I don't use a steel pipe anymore but a high quality ceramic one instead. Devided into three parts, as the drawing shows.

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.

All this results in a core that is behaving itself nicely once upto working temperature. The door assembly is what I intend to use for the final model. Air is coming in at both side's upper half and the top of the lower door frame. The firebox sports a space under a sort of grid, this prevents the coals to build up in the rear end. No separate air for under the grid, no separate secondary air provision. Size of air inlet is less important in this design, simply because the core is slowing down by itself when a fuel overload is imminent. It seems to be scalable, I expect it to be capable of running without a door at all.

The file is SketchUp v8, the lowest common denominator and done in inches. pberg0.home.xs4all.nl/pictures/dev2021/ the file is DSR3coreinch.skp.

Have fun!

[DCish]

Very exciting - I can't wait to hear the results of the certification test when that time comes!

[peterberg]

Feb 4, 2022 5:27:29 GMT -8 DCish said:

Very exciting - I can't wait to hear the results of the certification test when that time comes!

I will report back, don't worry. As you, I can't wait for the results either.

[grga]

I like the design and keep my fingers cross for the best results.

In my build (180mm) ordinary batch box with bell I have some small issues with unburned embers - well they do burn in the next burn but not all so it accumulates a bit and need to be emptied after cca. 5 burns. It is still ok but I am collecting ideas how to improve this in my next build.

In your new design you have space beneath the iron grid... I am thinking, guessing: to have the smallest amount of unburned embers the air should come also from bellow the grid, through the embers so that they burn faster. Since air openings are only to the side and at the top of the door then probably none air is coming from bellow the grid? It could be that could air entering would by itself fall down bellow the grid and some of it would also travel through the grid up. But most of the air, (I guess is heated relatively fast) would therefore go directly to the port (and not through embers).

Would it be any better if in the end phase of burning (mostly glowing embers left) the air could be redirected to travel only through the grid up by making another opening for air in the lower door frame. So you would close upper air inlets and open only the lower one. Would this improve the ember situation or only complicated the design?

[peterberg]

Or you could follow the Austrian method: closing the air inlet before all embers are burnt. The next fire will be built on top of those. Since the charcoal sports a lower self-ignition temperature compared to the woody fuel itself, the fire tend to burn easily under the pile of fuel. Changing of your own behaviour could be the solution, in my opinion. The design has been simple from the start, making it more complicated isn't my thing.

The Austrian method is what I practised for years, I've got no building up of coals as long as the leftovers aren't a big pile. But then, I use the thing as a batch device only, just one batch every run and no refilling.

[foxtatic]

Feb 4, 2022 3:35:41 GMT -8 peterberg said:

Thanks for sharing! I looked at the file and it all makes perfect sense. I do have a question about the door air inlet: The inlet on the bottom of your door frame is behind the attachment flange. So since the whole flange would be attached flat against the stove body, how does it get air?
Is this because your particular stove body is metal and there is a cutout at the floor where air flows up and into the door frame inlet?

I'm guessing on any other build (like a masonry bell) the air inlet could just open to the front like the test unit on your videos.