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Post by matthewwalker on Feb 16, 2015 at 1:17am
I spent some of last week traveling and have an awesome new thingy to share. I went to Eugene to hang out with Max and Eva from Firespeaking, Lasse Holmes, Leslie Jackson, Kiko Denzer, and few other lovely people. Max, Lasse, and Kiko had been playing with variations of Firespeaking's Cabin Stove.They had most of the heavy lifting done when I got there, so I mostly got to relax and eat amazing cake, which was awesome. We put some finishing touches on the heater on my first day and ran a few tests the next morning. I don't have any graphs to share at this early stage as there is still quite a bit of development to do, but the initial results are very promising. It's basically a side batch a la Adiel and Shilo, with a very short riser. Coincidentally, I had just been expressing my skepticism of short risers to Peter earlier last week. I was excited to see how this one did, and much to my surprise, it burned quite well. Not as amazingly complete of a combustion profile as our normal risered configurations, but still very clean and quite efficient. In it's initial set up, which can be tuned quite a bit, it was exceeding 80% efficiency with CO numbers down below 100 at times. I'm really inspired and excited, so much so that I've been home just over 24 hours and already stacked up two more burn chambers of similar designs and had fires last night. There will be more on this in the coming weeks I'm sure. Max is planning a write up in his Home Heat archive so keep checking over there, and I'll write up more as I go. I probably won't share many details of the internals and let Max, Lasse, or Kiko share what they would like about that. But, at this stage I'm thrilled with the possibilities here, and am so glad to have gotten to be a part of this process. Here's a shot of the stove as I left it. The crew was working on the hardware so I'm sure it will be even more stunning once it gets the big windowed door on there.  |
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Post by patamos on Feb 16, 2015 at 2:36am
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Post by matthewwalker on Nov 10, 2015 at 2:44am
Well gang, I have had intentions of creating plans for my cook stove, built around my Walker Riser-less Core. Life has a way of getting in the way, and I have had a lot of requests for plans and more info of late. I am not going to get to actual plans any time soon, but I believe wholly in this core and stove and really want others to experience it, it has improved my quality of life exponentially. So, I just threw the unedited photo folder of my build up, and linked to it from my site. There are a lot of photos, and it needs editing and captions and more info, but for anyone wondering about the details of my cook stove, it should answer a lot of questions. Feel free to email me through my site with any questions or suggestions regarding making the info more useful for folks who might build one. Here's the link: walkerstoves.com/walker-brick-cook-stove.htmlHopefully some of you will find this useful. |
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Post by dustylfc on Nov 10, 2015 at 4:10am
Thanks very much matt thumbs up
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Post by foxpause on Nov 11, 2015 at 12:56am
Wow, these cook stoves are amazing. I am about to build my first outdoor rocket batch heater based on your barrel design Matt so am a long way away from something like this but hopefully someday. Absolutely beautiful design.
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Post by Vortex on Nov 11, 2015 at 1:52am
Well done Matt. Nice to see such a well documented build.
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Post by matthewwalker on Nov 11, 2015 at 5:32am
Thank you very much Trev and Fox, I really appreciate the feedback.
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Post by ericvw on Nov 18, 2015 at 4:33am
Great photos, Matt! I really like the cinderblock base- very cool...literally! Aside from the cook surface, how well is the unit doing at heating the space overall?
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Post by alanloy on Nov 18, 2015 at 6:41am
I love your riserless core. Have you used it for a heater yet? I presume you could end up with a much more compact design than the usual RMH
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Post by matthewwalker on Nov 18, 2015 at 9:34am
Thanks guys. Eric, it's warm in here, for sure. Alan, no, I've only built the one.
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Post by matthewwalker on Apr 10, 2016 at 10:12pm
Hi Guys, I finally got around to filming a little intro to my cookstove, after a year of use. This should give you guys some more data, although it's mostly a non tech overview for the masses. Feel free to ask whatever, the basic gist of it is that I wouldn't change a thing. I am extremely satisfied with this one. Enjoy!  |
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Post by peterberg on Apr 11, 2016 at 2:10am
Hi Matt, To my surprise, I saw the slit in the vertical part of the pre-port tube is facing the back wall (or window?). Seems not logical since the flames are supposed to go through the port which is situated to the left. The csa of the rectangle duct and the round duct seems to be about the same. And the slit is also that same csa plus the top is open. I am wondering where the air is actually getting out, the slit or the top or both? I have to admit I tried a couple of different layouts analogue to yours in my own house heater. Same size ducts and recommended slit with top closed didn't do the trick. Top open and no slit at all was no good either. So, maybe there's an unknown effect in play here, like the air is rushing out on top and sucking through the slit combustion products in. In my opinion, directly behind the round vertical tube there isn't as much as an underpressure, actually there's a wake like what Ludwig Prandtl discovered by placing a sphere in a windtunnel.  By projecting this behind the tube, it looks like there could be mixing going on inside plus a sort of combustion gas regeneration. I couldn't repeat your results, perhaps due to very low exhaust temps, resulting in not enough underpressure in the system. And no bypass to solve that particular problem. In all, I tried 12 different layouts and several types of duct but that's another story for another thread. What do you think, does it sound plausible, this suction idea? |
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Post by matthewwalker on Apr 11, 2016 at 4:39am
Yes Peter, it is possible. Draft is required for it to work, as is a bit of warm up time. Also, I meter the fuel quite a bit more than you tend to, it won't work in a full tilt burn like you are accustomed to. It will overfuel fairly easily.
But, yes, as we spoke about, I have found neither of the configurations you tried to work as well as the combination of slit and open top. My guess is expanding gasses due to heating in the inlet channel use up all of the available exit CSA, far exceeding inlet CSA. In other words, the volume of the secondary charge where it enters the channel and the volume where it exits are vastly different, so CSA should follow.
Your theory is another that may explain it. It is interesting, for sure. I can watch it though, so I have a lot more data. Maybe I'll film a few minutes for you now that the glass is clean. I'm excited to hear you are exploring it Peter, I'm quite pleased with it as a unit to live with. It may not be the dragster you love so much, but it functions very smoothly across a lot of modes.
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Post by matthewwalker on Apr 11, 2016 at 4:42am
Oh, also, if you watch the video again and look closely, you can see the hottest part of the walker tube, as the metal is reddend and starting to oxidize more than the rest. It looks to be right at the top lip of the open top, I don't remember where in the circle though.
edit: Just watched again. At about 4:45 it appears to be, oddly enough, on the outside edge of the upper exit, just outboard of the slit. Strange.
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Post by peterberg on Apr 11, 2016 at 5:45am
This corrosion is caused by high temps and plenty of oxygen, it looks like the opposite of the port is affected most.
My experiments are ended now, I've done 118 test runs this winter with different floor channels, even bare ones with no vertical part. A number of the vertical parts oxidized badly in a very short time frame, especially at the top of the tube. The one which I am settled on is quite different from yours, smaller, shorter, square and no slit at all, rather an opening at the back top facing the port.
I'll report about this experiments in a separate thread when I can find time.
edit:
Placing the tube out of the middle is a neat trick to keep it straight, though.
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