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Post by esbjornaneer on Oct 31, 2017 2:16:23 GMT -8
Have Allerton Abbey had another go at firing the range up since your try? It will be good to know how it goes when they do.
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Post by peterberg on Oct 31, 2017 3:10:38 GMT -8
In my first build the FB walls were 4cm thick heavy firebrick with insulation on the outside. I guess it would have held heat longer if it had been thicker (laid flat instead of on edge) but it would also take longer/more wood to heat up to cooking temp. How thick would you consider making the walls of the FB for an oven effect? I would say the thicker firebricks or laid flat. So that would be 65 to 100 mm for the FB walls.
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Post by peterberg on Oct 31, 2017 3:12:13 GMT -8
Have Allerton Abbey had another go at firing the range up since your try? It will be good to know how it goes when they do. Haven't heard about plans to do so, the chimney would need to be cleaned and renovated first anyway. And installing a bypass would help immensely. My plan was to hook it up the same chimney as the existing batch rocket was using so we could heat up the chimney that way. I always strive to finish my work but this time it wasn't the case.
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Post by esbjornaneer on Oct 31, 2017 4:50:38 GMT -8
I would say the thicker firebricks or laid flat. So that would be 65 to 100 mm for the FB walls. Would the effect be the same having 40mm fire brick with 60mm mud/cob plaster as 100mm fire brick? And would you insulate outside that before an exterior facing?
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Post by diaspora on Nov 6, 2017 12:26:33 GMT -8
Hi Peter, If i want build a system that is equivalent to 180mm, can i multiply all dimensions by 1.2? Or maybe port and floor channel needs different calculation? I plan to build it with ceramic fiber boards.
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Post by Deleted on Nov 6, 2017 23:11:55 GMT -8
Hi all, peterberg DCish , very nice to see how you changed the whole thing.. we are tweaking with the details and you went a step back to completely modify the core ! Awesome ! Your experiments made me think.. with the standard batch core we tend to make a very voluminous bell right above it BUT this kills the afterburning possibilities you are playing with, no ? What if : 1- we reduced the height of the normal heat "riser" to something like 6B 2- we made a very small (in term of volume) first bell right above it, in order to make an "afterburner" to compensate for the smaller riser 3- then the gases would go to the rest of the system in normal conditions Here is a sketchup plan with this configuration. It's a very small kitchen range with a bench in option. The U-turn creates this "afterburner" volume : Here is the .skp plan : uzume-asso.org/assets/docs/experiences/cuisiniere_2500W/batch165_sidewinder_cuisiniereV2_1.skp
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Post by pinhead on Nov 7, 2017 7:02:00 GMT -8
Hi all, peterberg DCish, very nice to see how you changed the whole thing.. we are tweaking with the details and you went a step back to completely modify the core ! Awesome ! Your experiments made me think.. with the standard batch core we tend to make a very voluminous bell right above it BUT this kills the afterburning possibilities you are playing with, no ? What if : ... The "afterburning" is done within the heat riser of the typical batch box. Your idea has been done successfully. However, this post really should be in its own thread as to not derail the original topic.
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Post by esbjornaneer on Nov 7, 2017 8:18:05 GMT -8
The "afterburning" is done within the heat riser of the typical batch box. Where does the 'after burn' happen in the shoebox fountain setup? And where should the heat be utilized? Or are we not out after the most effective burn in this setup as we are looking for something that will work well to cook on? One thought I had about reaching highest temps in the fire box & fountain chamber... would it make sense to use a glass between the two chambers as there will be less mass to heat up compared with fire bricks? ...may still need to make the outline of the port with bricks, as I seem to remember from the batch box thread that there was a need for 'thickness/length' in the port to get the rams horns to develop. Are there any feelings yet about how long a cooking time one has from one batch of wood? And if the fire box is used as an oven how many burns/loads/batches are needed to get a loaf of bread baked when the walls are 3-4" thick? (I have heard of traditional bread ovens with 4" thick shells needing up to 4 hours of fire before baking in it.) Were the cores that have been build ever reloaded with more wood? How did that alter the burn quality as the embers now are below the wood while the first lighting was to be made on top of the wood? Full of questions and patiently waiting to build one of these, Esbjorn
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Post by Deleted on Nov 7, 2017 8:47:41 GMT -8
Hi pinhead I know that the afterburning is normally done in the heat "riser" but the height of the riser makes the heaters look "massive" and is not suitable for mass cookstoves. That is why I proposed this shortening plus another afterburning zone to keep the emissions low. When you wrote "Your idea has been done successfully." I think you refer to the thread "scandal" by Shilo when he said that it was enough to use a riser height of 4 instead of 8 BUT I think it he forgot to mention very essential things that make for a clean combustion with such a little riser. The thing is that in my experiments with the Testo analyser I've only seen that a 4B heat riser leads to a batch not burning cleanly. Every time the pyrolysis gets too intense, the small heat riser is just not able to burn all those gases. The result then is clear : in a normal bell heater, the batch core with a 4B heat riser doesn't produce the clean and stable combustion a 8B heat riser does. I think that behind the findings by peter and brian, there is this idea of a small volume where the gases produced by the pyrolysis of the wood in the firebox burn. My question is : what if theses fidings apply to the first batch core ? Regards,
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Post by matthewwalker on Nov 7, 2017 9:00:34 GMT -8
Here is my Testo tested design for a cook stove core. walkerstoves.com/walker-riser-less-combustion-core.html It's pretty similar to the suggestion above. May I suggest that, just like Peter's BBR, there is a tested/proven excellent design that already achieves these goals. In my opinion, one seeking to build a cook stove rocket would do well to build one of these to spec to see what is possible, then go ahead and improve on it to meet your goals.
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Post by Deleted on Nov 7, 2017 9:34:32 GMT -8
Hi matthewwalkerI hope my words are not misinterpreted, I was just posting an idea I found relevant for the current post, but may have been wrong ! I know your cookstove and I love it.. I was so motivated by your design that I made a heater based on it : uzume-asso.org/batchrocket_012017.htmlI changed the secondary air and other things so my testo analysis cannot be compared.. but your experiments and testo mesures where made with those lightweight insulating firebricks, no ? I used these bricks in the past but they where not abrasion proof at all. So I cannot use them on a heater I sell to a client. So I'm still trying to find a good design without using this insulating firebricks in the firebox. That is why I proposed this other heater configuration in my previous post. Regards,
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Post by pinhead on Nov 7, 2017 9:45:46 GMT -8
The "afterburning" is done within the heat riser of the typical batch box. Where does the 'after burn' happen in the shoebox fountain setup? And where should the heat be utilized? Or are we not out after the most effective burn in this setup as we are looking for something that will work well to cook on? One thought I had about reaching highest temps in the fire box & fountain chamber... would it make sense to use a glass between the two chambers as there will be less mass to heat up compared with fire bricks? ...may still need to make the outline of the port with bricks, as I seem to remember from the batch box thread that there was a need for 'thickness/length' in the port to get the rams horns to develop. Are there any feelings yet about how long a cooking time one has from one batch of wood? And if the fire box is used as an oven how many burns/loads/batches are needed to get a loaf of bread baked when the walls are 3-4" thick? (I have heard of traditional bread ovens with 4" thick shells needing up to 4 hours of fire before baking in it.) Were the cores that have been build ever reloaded with more wood? How did that alter the burn quality as the embers now are below the wood while the first lighting was to be made on top of the wood? Full of questions and patiently waiting to build one of these, Esbjorn The "top shoebox" replaces the heat riser in the typical Batch Box; the "afterburn" is done within the "top shoebox" as is done within the heat riser. The rest of your questions are as of yet unknown with the design of the original post; the core is still in the development stage and has yet to be attached to any heat harvesting device.
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Post by matthewwalker on Nov 7, 2017 10:51:45 GMT -8
So I'm still trying to find a good design without using this insulating firebricks in the firebox. That is why I proposed this other heater configuration in my previous post. Regards, I understand, I was not sure if you had seen it or not. I believe all batch rockets benefit greatly from insulated builds, so I insist on them. That said, you may find that a build of this core with the abrasion areas built of heavy brick functions well enough to meet your goals. Edited to add: I had not seen that heater of yours. Very cool! I imagine it would benefit greatly from insulation in all of the afterburner areas. A ceramic board liner over heavy brick is a great way to achieve this.
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Post by satamax on Nov 7, 2017 13:28:12 GMT -8
I'll say it again. Peter, this is verry intetesting.
I haven't paid real attention. How's the secondary air implémented?
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Post by satamax on Nov 7, 2017 13:56:12 GMT -8
I'll say it again. Peter, this is very interesting. I haven't paid real attention. How's the secondary air implemented? Well, ney worries. I found it on the ketchup. Which i finally managed to open. I wonder if the burn would be better with a S portal like arrangement.
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