jrl
Junior Member
Posts: 101
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Post by jrl on Jun 24, 2014 10:32:24 GMT -8
That's awesome! But that's a batch box with a large wood load. And there is no J tube, just a riser like the camping stove design. Will a J-tube do the same thing?
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Post by satamax on Jun 24, 2014 10:50:21 GMT -8
Well, if it goes into "scramjet" mode i think so www.donkey32.proboards.com/post/5381/threadWell, sorry, i can't find any of a J tube pulsating. The secret is low mass refractory, insulated like mad. Brick rocket do work, and well, but they take time to come up to speed. (xept if they're made out of insulating firebricks) What kind of wood have you used? Straight and bone dry 1/2 inch sticks, packed tight'ish in the feed tube, and lit with denatured alcohol should give you the best flame thrower effect.
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Post by peterberg on Jun 24, 2014 12:06:07 GMT -8
Well, sorry, i can't find any of a J tube pulsating. Here"s one, in fact there are 4 video clips made during these experiments. Unimaginary numbered 01, 02, 03 and 04. This is the last one. Persuading a J-tube into this is much harder to do as compared to the batch box design.
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jrl
Junior Member
Posts: 101
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Post by jrl on Jun 25, 2014 6:31:31 GMT -8
Well, sorry, i can't find any of a J tube pulsating. Here"s one, in fact there are 4 video clips made during these experiments. Unimaginary numbered 01, 02, 03 and 04. This is the last one. Persuading a J-tube into this is much harder to do as compared to the batch box design. Thanks Peterburg. I'm honored you've jumped into this thread. I've read through most of your threads on batch box development and it's fascinating. So far I've been very frustrated with J-Tubes and the smoke-back, fire creep, and the general concept of having an open feel tube in my house. My wife wants a sealed system with door and adjustable air intake. My biggest constraint on my design here is space. To make a 6" CSA batch box fit within this space I need to either have a 90 degree angle batch box (first picture below), which doesn't seem like it would work. Or, I have to have to go sideways with it and have the loading door along the length of the side (second picture below). I don't have the space to do the traditional design unless it's a 4" system. 90 Degree Batch Box: Side Load Batch Box: A few questions for you: Am I correct to assume that the 90 batch box above woudn't work? Do you see problems with having the loading door on the side of the box? How well did a 4" system work, if you've tried it? If my riser can only be 30", can I still have a 6" CSA and get away with it, or would the system stall out or something? And if I have a wider riser that's only 30" tall, are there aspects of the batch box would you change to offset having a shorter riser? Or is it better to simply scale the CSA down? The batch box for a 4" system seems too shallow in depth to fit any split firewood. What would be the effect of keeping with the dimensions of a 4" system (5.76" W x 8.64" H), but lengthening the box from 11.52" to 14"? In my design, I am sealing off a fireplace like a fireplace insert would, and then rocketing into the fireplace chamber and using the fireplace itself as a bell. I'd utlize the adjustable plunger tube suggested by Satamax. The CSA of the chimney flue is larger than the CSA of the plunger tube. And, the CSA of the plunger tube is larger than the CSA of the the rocket system. Therefore, there should always be a negative pressure and draw up the chimney. Would rocketing into the sealed fireplace chamber create a positive pressure (in the bell) that might try to expell itself into my house through any tiny cracks in the front facing? Or would the system regulate itself to a level that balances the pressures? I believe when you add up all the fireplace walls and ceiling my ISA of the bell comes out to roughly 3 m^2. Should the system be scaled down to a smaller CSA in support of the smaller ISA?
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Post by satamax on Jun 25, 2014 8:31:19 GMT -8
Here"s one, in fact there are 4 video clips made during these experiments. Unimaginary numbered 01, 02, 03 and 04. This is the last one. Persuading a J-tube into this is much harder to do as compared to the batch box design. Thanks Peterberg. I'm honored you've jumped into this thread. I've read through most of your threads on batch box development and it's fascinating. So far I've been very frustrated with J-Tubes and the smoke-back, fire creep, and the general concept of having an open feel tube in my house. My wife wants a sealed system with door and adjustable air intake. My biggest constraint on my design here is space. To make a 6" CSA batch box fit within this space I need to either have a 90 degree angle batch box (first picture below), which doesn't seem like it would work. Or, I have to have to go sideways with it and have the loading door along the length of the side (second picture below). I don't have the space to do the traditional design unless it's a 4" system. 90 Degree Batch Box: Side Load Batch Box: A few questions for you: Am I correct to assume that the 90 batch box above woudn't work?Do you see problems with having the loading door on the side of the box? How well did a 4" system work, if you've tried it? If my riser can only be 30", can I still have a 6" CSA and get away with it, or would the system stall out or something? And if I have a wider riser that's only 30" tall, are there aspects of the batch box would you change to offset having a shorter riser? Or is it better to simply scale the CSA down? The batch box for a 4" system seems too shallow in depth to fit any split firewood. What would be the effect of keeping with the dimensions of a 4" system (5.76" W x 8.64" H), but lengthening the box from 11.52" to 14"? In my design, I am sealing off a fireplace like a fireplace insert would, and then rocketing into the fireplace chamber and using the fireplace itself as a bell. I'd utlize the adjustable plunger tube suggested by Satamax. The CSA of the chimney flue is larger than the CSA of the plunger tube. And, the CSA of the plunger tube is larger than the CSA of the the rocket system. Therefore, there should always be a negative pressure and draw up the chimney. Would rocketing into the sealed fireplace chamber create a positive pressure (in the bell) that might try to expell itself into my house through any tiny cracks in the front facing? Or would the system regulate itself to a level that balances the pressures? I believe when you add up all the fireplace walls and ceiling my ISA of the bell comes out to roughly 3 m^2. Should the system be scaled down to a smaller CSA in support of the smaller ISA? donkey32.proboards.com/post/11642/thread
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jrl
Junior Member
Posts: 101
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Post by jrl on Jun 25, 2014 10:10:37 GMT -8
Thanks Peterburg. I'm honored you've jumped into this thread. I've read through most of your threads on batch box development and it's fascinating. So far I've been very frustrated with J-Tubes and the smoke-back, fire creep, and the general concept of having an open feel tube in my house. My wife wants a sealed system with door and adjustable air intake. My biggest constraint on my design here is space. To make a 6" CSA batch box fit within this space I need to either have a 90 degree angle batch box (first picture below), which doesn't seem like it would work. Or, I have to have to go sideways with it and have the loading door along the length of the side (second picture below). I don't have the space to do the traditional design unless it's a 4" system. 90 Degree Batch Box: Side Load Batch Box: A few questions for you: Am I correct to assume that the 90 batch box above woudn't work? donkey32.proboards.com/post/11642/threadThat's awesome! If that offset design would work, that would address my space constraint. From the look of that, the right hand corner where the port to the riser is has an offset as well. In that I mean there is a brick that protrudes into the firebox in far right hand corner on the left side of the port. Whereas the right side of the port looks flush with the right hand wall of the firebox. Does that create a cyclone? Is that significant to the design?
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Post by satamax on Jun 25, 2014 10:32:21 GMT -8
JRL, i haven'y tried the side riser batch arangement, so i can't say much more.
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Post by peterberg on Jun 25, 2014 11:15:29 GMT -8
Hi jrl, I'll try to answer some of your questions. Am I correct to assume that the 90 batch box above woudn't work? It will work, definitely, exactly as you've drawn. Adiel in Jerusalem built at least one succesfully. See the thread Max mentioned. Do you see problems with having the loading door on the side of the box? This can be done as well. Not tried myself but I know of Joris Pouls, a guy in Belgium who've done this. The air intake ports are a little complicated, not everyone's first time build I would say. How well did a 4" system work, if you've tried it? Didn't try this myself, but John from Virginia did one succesfully. There's a thread somewhere with reports and experiences. If my riser can only be 30", can I still have a 6" CSA and get away with it, or would the system stall out or something? And if I have a wider riser that's only 30" tall, are there aspects of the batch box would you change to offset having a shorter riser? Or is it better to simply scale the CSA down? When you have a good chimney to use for this stove, you can get away with 30" riser in a 6" system. It's best to stick to the proportions spreadsheet otherwise. The batch box for a 4" system seems too shallow in depth to fit any split firewood. What would be the effect of keeping with the dimensions of a 4" system (5.76" W x 8.64" H), but lengthening the box from 11.52" to 14"? The batch box design works like a tunnel oven. So it can be lengthened, the maximum length I've tried is 2'in a 6" system. In my design, I am sealing off a fireplace like a fireplace insert would, and then rocketing into the fireplace chamber and using the fireplace itself as a bell. I'd utlize the adjustable plunger tube suggested by Satamax. The CSA of the chimney flue is larger than the CSA of the plunger tube. And, the CSA of the plunger tube is larger than the CSA of the the rocket system. Therefore, there should always be a negative pressure and draw up the chimney. Would rocketing into the sealed fireplace chamber create a positive pressure (in the bell) that might try to expell itself into my house through any tiny cracks in the front facing? Or would the system regulate itself to a level that balances the pressures? At first, there will be a slight overpressure in the bell when the stove is started cold. Within 5 minutes this will turn into an underpressure and will stay that way during the entire burn. Nothing will come out of tiny cracks. Unless, of course, the chimney is stalling. Again, you have to have an adequate chimney for this stove. I believe when you add up all the fireplace walls and ceiling my ISA of the bell comes out to roughly 3 m^2. Should the system be scaled down to a smaller CSA in support of the smaller ISA? Tricky question. In this case you could scale the thing down or fill the fire box only half, I don't know for sure.
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Post by peterberg on Jun 25, 2014 11:24:26 GMT -8
That's awesome! If that offset design would work, that would address my space constraint. From the look of that, the right hand corner where the port to the riser is has an offset as well. In that I mean there is a brick that protrudes into the firebox in far right hand corner on the left side of the port. Whereas the right side of the port looks flush with the right hand wall of the firebox. Does that create a cyclone? Is that significant to the design? No it isn't a brick protuding into the firebox. The whole heart of the thing is an assembly of cast products, by the way. What you see is a chamfer of 45 degrees in order to avoid a dead corner. The rest of the configuration is more or less the same as the straight batch box design. Please read the whole thread of this side riser design, he tried also the cyclone idea by accident I believe, but that didn't work satisfactorily. (did I spell that right? Sometimes I am just quessing, sorry.)
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jrl
Junior Member
Posts: 101
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Post by jrl on Jun 25, 2014 11:57:38 GMT -8
That's awesome! If that offset design would work, that would address my space constraint. From the look of that, the right hand corner where the port to the riser is has an offset as well. In that I mean there is a brick that protrudes into the firebox in far right hand corner on the left side of the port. Whereas the right side of the port looks flush with the right hand wall of the firebox. Does that create a cyclone? Is that significant to the design? No it isn't a brick protuding into the firebox. The whole heart of the thing is an assembly of cast products, by the way. What you see is a chamfer of 45 degrees in order to avoid a dead corner. The rest of the configuration is more or less the same as the straight batch box design. Please read the whole thread of this side riser design, he tried also the cyclone idea by accident I believe, but that didn't work satisfactorily. (did I spell that right? Sometimes I am just quessing, sorry.) Thanks for answering my questions. Doing this offest design was one of my original thoughts on this project, but I never thought it would work. Now I'm inspired. Maybe you mentioned this in another thread, but what mixture of aggregates have you used to do your cast pieces? How do you avoid cracking? A 55 LB bag of refractory cement in my area is $50 US. Fireclay is not available in my state. I would like to experiment with doing castings but the material cost is too high relative to fire bricks. I'll probably use just firebricks since they are only $1.85/brick and can be cut to shape.
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Post by satamax on Jun 25, 2014 12:51:09 GMT -8
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Post by peterberg on Jun 26, 2014 2:05:57 GMT -8
Maybe you mentioned this in another thread, but what mixture of aggregates have you used to do your cast pieces? How do you avoid cracking? I've never mixed the ingredients myself, always bought the commercial available castable refractory. The temperature stress in a rocket stove casting is quite severe, you have to devide it into smaller pieces to avoid cracks. I've made the whole casting into a left and right half and accepted there will be cracks. Remember, not the hottest parts will crack but the cooler parts instead. Those will be lagging behind as the hottest spots expand through the rising temperature.
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jrl
Junior Member
Posts: 101
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Post by jrl on Jun 26, 2014 7:03:14 GMT -8
The offset batch box was a success last night. I mudded firebricks into the crude form sticking as closely as possible to the Peterburg Batch Box Dimensions spreadsheet. Since my structure was not at all air tight I didn't expect much, but was suprised to see a roaring rocket flame extending a foot up into the riser. So now that I know that design is possible, I'm on to the next set of design challenges.
If the batchbox and riser are contained in the fireplace behind a steel wall, do you think it's better to exhaust directly into fireplace, or should I put a small barrel/vessel over the rise and force it to exhaust down down the sides of the barrel open at the bottom and then out into the fireplace chamber? Will a barrel slow the system down or speed it up? It would be ideal if I could make the exhaust be force to flow along the front steel wall.
If the CSA remains at or slightly above 6 inches coming out of the 6-inch riser, can the exhaust take an immediate 90 or 180 degree turn at the top of the riser? Could it flow up the riser and then over and down another fire brick riser? From the bottom of the second riser I could then channel the exhaust up along the steel wall (weld a U channel >=6" CSA into the steel wall) to make the wall a heat exchanger to my living space.
Or, conversely, does the heat exhange need to happen directly at the top of the heat riser?
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Post by peterberg on Jun 26, 2014 10:40:55 GMT -8
..., do you think it's better to exhaust directly into fireplace, or should I put a small barrel/vessel over the rise and force it to exhaust down down the sides of the barrel open at the bottom and then out into the fireplace chamber? Will a barrel slow the system down or speed it up? The barrel will slow things down, for certain. Exhausting directly into the fireplace would be preferable. If the CSA remains at or slightly above 6 inches coming out of the 6-inch riser, can the exhaust take an immediate 90 or 180 degree turn at the top of the riser? This will only work nice when the space above the riser is about 200% of system size. Could it flow up the riser and then over and down another fire brick riser? From the bottom of the second riser I could then channel the exhaust up along the steel wall (weld a U channel >=6" CSA into the steel wall) to make the wall a heat exchanger to my living space. Please forget about channeling the gases through ducts of some sort. In a bell of whatever shape or material, all the hot gases comes down along the walls provided the riser is centered. When the riser is off-center, the majority of the gas volume will choose the wider space. So don't try to be overly smart, place the riser off-center at the back and make the front out of a steel plate. This way the front will be hottest, all by itself. Provided the bell of whatever material and whatever shape is wide enough as compared to system size, the whole gas stream will obey the laws of gravity, no exeptions.
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