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Post by mhkhankan on Jan 20, 2013 16:03:01 GMT -8
[Dear Peter and every one, Thanks for all the information that you guys shared with us so far.
I am new to this forum plus I am new to the whole idea of a rocket stove.
But I have to say that I was inspired by you guys to the point of wanting to get involved and experiment.
I did a design using sketchup so please forgive me if I made some mistakes. The concept is simple but I think I am crazy enough to have thought about it so please feel free to criticize me. I borrowed the stove design from Peter and I thought of an application for it. I could be 100% wrong so be soft on me. I am willing to experiment on it if this concept is valid in the first place. The drawing is just an illustration of the Application.
So get ready to launch your attack on me ......Peter Please let me have your thoughts on this since the batch box stove optimization is yours.
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Post by mhkhankan on Jan 20, 2013 16:23:18 GMT -8
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Post by peterberg on Jan 21, 2013 3:21:58 GMT -8
Mhkhankan, welcome to the boards.
I've started another thread and moved your messages in order to keep the original thread from clogging up any further.
And now on to your questions, it would be helpful to use question marks where appropriate, by the way.
I've looked at your pictures and couldn't figure out where the smoke is supposed to go after leaving the riser. Bear in mind the cross section area of the smoke channels should be at least the same as the riser. When your intention is to use one or more bells in the system, the c.s.a. of these should be at least 4 times as large as the riser, preferably a lot more.
Could you elaborate on the gas path through the system? That would help a lot to understand what direction you want to go.
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Post by peterberg on Jan 21, 2013 4:12:12 GMT -8
How do you upload pictures to this forum anyway? When you open a new reply window, the second row from the top do contain the word "Attachment". The same row slightly to the right should say "select file" or something like that. My own forum window is using my mother's language which isn't English so I don't know what the exact words are. |
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Post by mhkhankan on Jan 21, 2013 19:01:22 GMT -8
Thanks peter for the replay. The application is nothing new about it but I think the Idea here is to use the batch box rocket instead of other types. The surface is made out of black steel for cooking and the other box is just an oven. Some of my questions are: can you use that little monster under an closed place such as 900x600x900? Is it safe? can we control the heat? If yes then can we exit the cooking cabinet to another container that will act as a heat radiator?
Sorry for the bad drawing, I will provide with better illustration or I will upload the skp file.
Thanks again...
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Post by mhkhankan on Jan 21, 2013 19:28:22 GMT -8
How do you upload pictures to this forum anyway? When you open a new reply window, the second row from the top do contain the word "Attachment". The same row slightly to the right should say "select file" or something like that. My own forum window is using my mother's language which isn't English so I don't know what the exact words are. Sorry Again for my drawing skills. Gasses leave the riser to the left according to the picture under the black plate which is the cooking plate and then around the box ' Oven' and exit over it into the flue or other container for heat radiation and not storage of any kind or use the flue as a heat radiator by adding some passive heat exchanger. I hope its clear. I will try to draw gasses path. |
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Post by peterberg on Jan 22, 2013 7:26:37 GMT -8
Gasses leave the riser to the left according to the picture under the black plate which is the cooking plate and then around the box ' Oven' and exit over it into the flue or other container for heat radiation and not storage of any kind or use the flue as a heat radiator by adding some passive heat exchanger. I hope its clear. I will try to draw gasses path. OK then. Probably the gap above the riser is too narrow, the same goes for the gap around the oven. Exhaust port of the stove should be better as low as possible in order to gain the most of the hot gases. More space around the oven is better, the velocity of the gases will be lower then. Is this stove for cooking on top and in the oven only, then it would be better to insulate around the outside in order to keep heat inside. |
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Post by mhkhankan on Jan 22, 2013 8:02:17 GMT -8
Peter,
Please tell me, is it safe to use a batch box rocket stove for such application ' I mean indoor within a kitchen setup' ? I am planning on using a combination of refractory Bricks for this setup and steel where needed 'Cooking plate and may be Oven Walls' what do you think. Is it OK to use 30mm Refractory Brick or should I increase the thickness? DO gasses path CSA should be 4 times the CSA of the heat riser or not? can I still exit this stove into other container for quick heat radiation?
Asking to much sorry for that? But your work inspires so many so thank you for the help.
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Post by peterberg on Jan 22, 2013 12:52:28 GMT -8
Please tell me, is it safe to use a batch box rocket stove for such application ' I mean indoor within a kitchen setup' ? Yes, should be no problem. Has already done before (not by me) and works like it is intended. I am planning on using a combination of refractory Bricks for this setup and steel where needed 'Cooking plate and may be Oven Walls' what do you think. Is it OK to use 30mm Refractory Brick or should I increase the thickness? The firebox is better built from 5 cm (2") fire bricks on its side. Any other part that suffers abrasion as well. DO gasses path CSA should be 4 times the CSA of the heat riser or not? can I still exit this stove into other container for quick heat radiation? Better to stick to the 4 times rule, this will slow the gases down and ensure a longer "stay" of the gases. And yes, when the exhaust temperature is high enough, you could couple another container for quick heat down the line. For example a 15 gallon (60 liter) barrel, preferably used as a bell. In effect, the inlet and outlet both at a low level, the inlet a bit higher as compared to the other opening. It's possible to build the whole stove out of fire bricks, but not necessarily. A question, do you need to have a white oven as sketched? Or could it be a black oven, one where the gases passing through? A black oven could be simply on top of the firebox, making the whole setup more compact. How large do you want the oven to be? |
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Post by mhkhankan on Jan 23, 2013 20:24:06 GMT -8
A black oven could be simply on top of the firebox, making the whole setup more compact. How large do you want the oven to be? Dear Peter, I created a spread sheet with a built in formulas that would help any body construct the Batch Box stove. I have taken all the numbers from your skp file and translated most of the relationship according to my understandings and readings. So please call it a rough draft and correct the numbers if I am wrong. To test the formulas I punched in the almost 8 inch system and numbers came out so again please verify it. I will upload the file so every body can use it once it is verified. I guess the only number that I do not like is CSA of the tunnel. Red numbers represent the mentioned percentages of different dimensions in these threads. Let us see if I did them correctly. Please explain the difference between black Vs. white Oven. I have an idea but I could be mistaken too. thanks |
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Post by mhkhankan on Jan 23, 2013 20:26:37 GMT -8
Almost Six Inch System
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Post by peterberg on Jan 24, 2013 2:54:49 GMT -8
mhkhankan, This a tough one, I had to recalculate all the dimensions. One of the members of this forum, Jham (Jim) from Blacksburg, Virginia came up first with the idea of relationships between the different dimensions of this stove. His way of calculating happens to be a bit complicated, so I've searched for a simpler way. A square riser c.s.a. compared to a round one is thought to have the same capacity when the diameter is equal to one side of the square. This is important! Port c.s.a. 70% of the riser c.s.a., plus or minus 1%. P-channel about 5% of the riser c.s.a. Overhang of the p-channel, over the port's ceiling, is the same as the gap. For example, the height of the channel for a 6" system is 20 mm, minus 4 mm, the steel thickness. That leaves us with 16 mm as the gap, overhang of the steel part is the same. This is really important, without the overhang it's possible to block the p-channel with a piece of fuel. This is a picture of the channel part:  And a higher res picture:The rest of the dimensions are derived from the riser diameter, to be precise 72.36% of it. The ratio list is like this: 1# firebox width 2, height 3, depth 4. 2# port width 0.5, height 2.2, depth 0.36 (this last one is not very important, keep the port as short as possible) 3# riser height 8 to 10. Don't forget the sloped sides of the firebox, handy for concentrating the coals in the middle. Presumably, these sides are playing a part in leading the air over the floor straight to the port. Thickness of the refractory material: as thin as practical possible, less mass equals quicker heating up. That's about all there is to it. Edit: Nearly forgot: the best results were obtained when the lower part of the riser, over the height of the firebox, was round or octagon. And the floor of the riser sloped from the port to the back of the riser. Both these additions proved to be very valuable. |
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Post by peterberg on Jan 24, 2013 3:03:50 GMT -8
Please explain the difference between black Vs. white Oven. It's really simple, actually. The black oven will become black inside because the smoke path is leading through it. The white oven will stay clean, the smoke path is leading around it. The black variant, when built out of fire bricks will heat up quicker as compared to the white one built of the same material. A steel oven is almost always a white one. |
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Post by mhkhankan on Jan 25, 2013 16:17:58 GMT -8
A square riser c.s.a. compared to a round one is thought to have the same capacity when the diameter is equal to one side of the square. This is important! Is it a rule of thumb or is it math? The reason why I am asking because I will scale down to smaller version, use bricks only and heat riser will be a Square. Peter, If you look at the picture you will see a comparison between what you have described and measurements I took from your skp file. The difference between 16 and 15 is 1mm in the height of the p-channel. the width of the channel is 54.3 using formulas and 51.6 from your file. Could you please explain these differences? The length of the P-Channel is 90 mm plus 15mm for the active part that makes the total length a 105mm. Is 90mm a fixed number no matter what the system size is? |
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Post by mhkhankan on Jan 25, 2013 16:35:08 GMT -8
2# port width 0.5, height 2.2, depth 0.36 (this last one is not very important, keep the port as short as possible) Looking again at the table we see some differences between my formula results and your SKP file. I am really concerned with width measurement more than the rest. because I think they are not important. Width 54.3 to 51.6, CSA of the port and Depth '' but you said keep it short and it is not important. Could you please explain and correct me if I am wrong? |
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