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Post by endrunner on Feb 22, 2013 13:45:23 GMT -8
Some of you know we have been working on offering Peter van den Bergs vortex j-tube. We have the 6" molds finished and did our first casting. Here are some pictures of the engine core. It is cast in insulating refectory with steel feed tubes and vermiculite heat riser. The white line in the burn tunnel is a gasket to allow for heat expansion and it is bound by stainless steel strapping. In this picture you can see the peter channel, it also has the very complicated wedges (trip wires) and vortex end The red metal box is a prototype container for test firing. I will post pictures of the inside shortly. And will post its firing graphs in a few weeks. We are working on getting a Testo 330 or 340 to provide lovely graphs like peter. Attachments:
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Post by endrunner on Feb 22, 2013 13:47:09 GMT -8
more pics Attachments:
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Post by endrunner on Feb 22, 2013 13:55:06 GMT -8
sorry topview Attachments:
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Post by endrunner on Feb 22, 2013 13:58:04 GMT -8
sideview Attachments:
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Post by endrunner on Feb 22, 2013 14:32:26 GMT -8
inside the tunnel Attachments:
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Post by Donkey on Feb 22, 2013 16:04:44 GMT -8
Nice build! I see that you've got the tripwire running down the side walls. It appears to be straight across too, it doesn't have the point to it.. I'm also seeing an interesting ledge at the opening to the heat riser. Sweep-to-ledge.. A second turbulence point? I thought that Peter had said (at one point) that he didn't notice an improvement with that ledge there, though I've often wondered about it.
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Post by endrunner on Feb 22, 2013 16:52:37 GMT -8
The top is angled and when the 2 pieces are put together it makes an arrow of sorts. I will let peter respond about the wedge prior to the heat riser. We built everything exactly to his measurements.
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Post by mechartnik on Feb 22, 2013 17:27:29 GMT -8
very nice work, have you set pricing for the cores yet?
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Post by endrunner on Feb 22, 2013 18:23:20 GMT -8
6" - Just the casting will be $200, if you want the full core, including the steel feed tube and heat riser, like what is shown, $500.
It is higher priced than what we wanted but, the high temp insulating refectory materials are expensive and the steel fabrication including the wings to enable the P-channel are also expensive, even in volume.
We will have see how many people are willing to pay for a quality core. Most RMH burn tunnels are built with fire brick, heat capture, not insulating material, so they will always be sub-par to an insulating cast tunnel, not to mention the stellar design.
Any feed back pro or con is appreciated.
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Post by Donkey on Feb 22, 2013 23:07:47 GMT -8
I think it's awesome. I think that $500 is NOTHING to pay for what this little guy should be able to do.
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Post by peterberg on Feb 23, 2013 5:26:14 GMT -8
I see that you've got the tripwire running down the side walls. It appears to be straight across too, it doesn't have the point to it.. At the picture, you see one half of the tunnel, stream is from right to left, ceiling at the top of the picture. The trip wire is visible at the ceiling as the half of an arrow, 20 degrees forward. This wire is also running at the wall, straight down this time, ending to zero at floor level. This is done in order to disrupt the laminar stream high along the wall. I'm also seeing an interesting ledge at the opening to the heat riser. Sweep-to-ledge.. A second turbulence point? I thought that Peter had said (at one point) that he didn't notice an improvement with that ledge there, though I've often wondered about it. The rounded back of the tunnel do consist of a larger radius along the wall as compared to the middle, converging the stream. Letting the two different roundings met at the straight ridge just at the start of the riser proved to be difficult. What you see there is a solution to this problem. However, it is doing something else as well, as I'd expect any remaining volatiles that are running along the bottom would sweep up and back into the flame just before entering the straight riser. As such, it will disrupt any laminar flow at the back of the riser entrance. That last feature hasn't been proven yet, but I fully expect it will work. All the above tricks and some smaller ones as well, are contributing to the capability of a very clean and hot burn. Whether or not this one is capable of pulse jet mode remains an open question. A good chimney stack and at least one foot of space above the riser are indispensable conditions as well to reach this so called pulse mode.
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dvawolk
Full Member
DSR2 125mm open system (actual project)
Posts: 256
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Post by dvawolk on Feb 23, 2013 7:04:23 GMT -8
I'd say the price is low, too!
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Post by Donkey on Feb 23, 2013 9:11:07 GMT -8
At the picture, you see one half of the tunnel, stream is from right to left, ceiling at the top of the picture. The trip wire is visible at the ceiling as the half of an arrow, 20 degrees forward. This wire is also running at the wall, straight down this time, ending to zero at floor level. This is done in order to disrupt the laminar stream high along the wall. Ah.. Now that you mention it, I see the angle. Odd that I thought I saw it as straight across before.. As you know, I've always focused on the low tech. Solutions that can be made by anyone, virtually anywhere. I wonder how much of this kind of design can be done reliably with more.. neolithic/post-apocalyptic methods and materials..
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Post by matthewwalker on Feb 23, 2013 10:08:28 GMT -8
That is a great looking core! I too think the pricing is very fair. Do you have a website, and when will they become available? I know of a couple pending builds that would be a perfect fit with this.
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Post by Donkey on Feb 23, 2013 10:12:18 GMT -8
Here's a website with various stove prices.. The cheapest is around $1,000 (American $$). Funny that the site is called Smokey's Stoves. Funny to me, in that it's ingrained in us that fire ALWAYS equals smoke, but really the name (for me) SHOULD be a dis-incentive to buy. Here's the Temp-Cast website, makers of masonry stove kits, where they are saying "The cost of a complete Temp-Cast core kit, not including chimney and facing, will generally fall in the range of $4000 to $5000".
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