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Post by briank on Sept 24, 2017 15:36:23 GMT -8
With the first prototype the highest I got on the top of the barrel was 865 degrees, and 615 degrees in the open pizza oven. Of course that was with 25” of barrel on top of the core and about 14” between the vertical riser and the barrel top. On this one there’s only 11” or 12” between riser top and barrel, and only about 17” of Barrel being heated. With similar weather, I finally lit this prototype this afternoon at 5:30 but was called away till 7:08. At that point, barrel top temp was 858• and pizza oven almost 600•. Peak temp has been after about 45 minutes after starting the fire in the first prototype. I’m pretty sure I missed peak this burn cycle. I’m using the same compressed sawdust fire bricks for direct comparison which burned 6 hours in the previous prototype. I’ll try to keep track of total burn time this cycle.  |
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Post by briank on Sept 24, 2017 16:45:38 GMT -8
Three hours into this burn cycle, barrel top temp 450• At 4 1/2 hours, Barrel top temp was 125• and most of the fuel burned up. I suspect it burned hotter/faster because I opened up/ reamed out the primary air ports in the barrel stove kit door assembly. I’m figuring peak barrel top temp probably reached 885•+ but I’ll have to run another batch to tell for sure. This version definitely has higher exhaust gas temps for heating a bell, bench etc.  |
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Post by briank on Sept 24, 2017 18:36:32 GMT -8
Also, honestly, before anyone looks at this and says it's too involved or too much work, please realize that this took me a while because I've had five strokes, but I have no background whatsoever in metal work or working with ceramics. This whole project was completed with a Harbor Freight angle grinder & 30" metal bender, a Makita cordless drill and driver, a table top grinder, some furnace cement, and simple hand tools. (I bought a cheap Craigslist band saw to cut the ceramic fiber board, but if I manage to get these into production as a vacuum formed ceramic fiber shippable core, that wouldn't be necessary.) The only thing I got help with was tack welding the secondary air assembly at a local machine shop ($12) and that was only because I was impatient and didn't want this project further delayed while I learned to weld on a Harbor Freight MIG welder I bought.
The eventual shippable core could be used in multiple types of rocket heater applications, not just the upright barrel shown. A cut down barrel would just be used to contain the ceramic core.
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Post by Dan (Upstate NY, USA) on Sept 26, 2017 1:06:43 GMT -8
How tall is your heat riser?
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Post by briank on Sept 26, 2017 11:27:31 GMT -8
How tall is your heat riser? The horizontal segment is about 16” and the vertical about 23” including the 8” segment of vacuum formed ceramic fiber riser on top of the core.  |
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Post by Dan (Upstate NY, USA) on Sept 27, 2017 0:36:01 GMT -8
Riser seems a little short, but there is no way of really knowing until you do some testing with this one and then a longer one...
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Post by Daryl on Sept 27, 2017 2:28:18 GMT -8
Be careful, Brian. There are people who will "borrow" your ideas and claim them as their own.
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Post by peterberg on Sept 27, 2017 3:14:13 GMT -8
Be careful, Brian. There are people who will "borrow" your ideas and claim them as their own. True, happened to me a couple of times. The only way to counter this effect is to publish it at the time the idea is ready for testing (or production). Bear in mind Brian's project is a development built on existing design which is Creative Commons licensed. This license asks for Attribution and Share Alike so new implementations are subject to the same open source license as well. People tend to pose restrictions on their own contributions to the batch box rocket design, no commercial use for example, but these restrictions can safely be ignored. |
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Post by Dan (Upstate NY, USA) on Sept 27, 2017 13:12:24 GMT -8
You know what would be really great... make the curved half a little shorter so you can ship it inserted into the box half. It would eventually lower shipping costs by a lot.
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Post by briank on Sept 27, 2017 20:14:11 GMT -8
You know what would be really great... make the curved half a little shorter so you can ship it inserted into the box half. It would eventually lower shipping costs by a lot. It will all fit in a 24” x 24” x 30” tall box and the ceramic core parts willbe around 50 pounds. Frankly, I still don’t know two basic things about whether this whole idea will be feasible: 1) Whether there is even a demand for it (the shippable core, which my Kickstarter should answer fairly quick) 2) What my cost per unit and the retail cost will be. I realize I’ve gone in an unorthodox direction with the design and shape of this core but it was based on a lot of experimenting and a design principle that it could be built entirely with off the shelf parts. I already have designs laid out so that it can be used as the core of a kitchen stove and oven and a basic rectangular shaped wood stove like a traditional home wood stove, in which case the bottom half of a barrel would be used simply as a metal container to hold the core. We’ve received invaluable feedback from the 4 manufacturers of vacuum formed ceramic fiber shapes I’ve contacted, and we’ve already redrawn our technical drawings twice based on that feedback. They are now waiting on our latest AutoCAD drawings, which are almost complete. Once I get them submitted I’ll finally have up front costs and per unit price nailed down. Our local university campus has a free small business incubator program and they’ve already invited me to come. They offer good advice on planning, financing and marketing so I’ll be attending the first meeting with them this Tuesday. |
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Post by Daryl on Oct 1, 2017 18:36:34 GMT -8
I realize I’ve gone in an unorthodox direction with the design and shape of this core Not exactly. It took me awhile to remember his name but Pekka Leskela (youtube) did a lot of early experiments with the mini box shape. I am sure others have too so the concept has some merit. |
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Post by briank on Oct 1, 2017 20:14:37 GMT -8
I realize I’ve gone in an unorthodox direction with the design and shape of this core Not exactly. It took me awhile to remember his name but Pekka Leskela (youtube) did a lot of early experiments with the mini box shape. I am sure others have too so the concept has some merit. I mean specifically shaping it to fit the curvature of a barrel. Versions scaled down to 16 and 30 gallon barrels would make for handy little camping stoves, while the design could easily be scaled up to 85 and 110 gallon barrel sizes, with corresponding changes in riser, firebox and Venturi port sizes. For a bit of a kick, a friend and I are going to do a 1/6 scale 3D printed model of this stove, using a 6" tall and 4" wide "barrel" (Pyrex jar or beaker) using flame retardant ABS 3D printing filament, Mica glass and a Pyrex jar, carbon felt and 1" Pyrex tubing with 1" copper elbows (for the black stove pipe). People will be able to more easily envision the smoke path and vertical riser exhausting inside the Pyrex "barrel," using lit matches (smoke) in the model firebox. It won't reach high temps so much as being a learning aid to help the wider audience unfamiliar with rocket heater technology to grasp the concept better. |
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Post by briank on Oct 3, 2017 7:57:10 GMT -8
Disappointing news - my traveling companion had to back out due to health reasons, and it's not a trip I can or should attempt by myself due to my own health troubles, so unfortunately I'm not going to be able to attend the rocket heater Jamboree in Montana after all.
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Post by briank on Oct 6, 2017 18:16:10 GMT -8
I’ve been traveling and just got a chance to run another batch of the compressed sawdust fire bricks tonight. I lit it around 6:45. Barrel top temps were as follows. Firebox door was open about a half inch. It gets too hot too fast that way! 7:20 575•F 7:30 930•F Closed firebox door 7:33 853•F I wanted to see how hot the pizza oven would get so I placed insulation blocks to block the pizza oven door: 7:32 450•F (firebox door closed) 8:02 640•F (cracked firebox door approx 3/8” open) 8:07 700•F At this point I figured I better check the barrel top temps, and it was over 1000•F on the laser thermometer and starting to glow red around the bases of the firebrick in the pizza oven, so I closed the firebox door and removed the insulation from the pizza oven doorway to let everything cool down. Barrel top temps 8:16 960•F 8:24 812•F (closed air) 8:31 733•F      |
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Post by briank on Oct 6, 2017 18:55:20 GMT -8
And at 10:45, four hours after starting this batch, barrel top temp is 445•F. It looks like there’s enough wood left in the firebox to burn another 1 to 1 1/2 hours, but I’m hitting the sack.  |
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