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Post by coastalrocketeer on Mar 16, 2019 9:12:06 GMT -8
the plate idea is likely workable, though I know nothing of the methods by which one could potentially solder aluminum to copper.
That plate as the top of a bell could be quite good I would imagine, and very easy to clean, compared to other things.
My idea for mine was to make it like the condenser coils under or behind a refrigerator. They are designed not to get clogged by particles too easily, and be easy to clean. The wire will provide good surface area enhancement and I have many 5-25’ sections of 3 conductor as scrap from remodeling, just have to strip and solder.
One should assume anything with small openings like a car radiator will need cleaning much more often than a more open design or a plate design as you suggested.
The only things I would worry about with the aluminum plate, though I don’t know enough to predict whether they would actually be an issue are:
•Potential melt down if in too hot an area of the stove (aluminum doesn’t glow like steel before turning to liquid) probably only a concern directly over the riser, and if the water is not able to sink heat away fast enough.
•Increased corrosion effects of dissimilar metals exposed to combustion byproducts combined with condensed water.
•Achieving good thermal bonding of aluminum to copper.
I don't see any potential issues beyond those, but others may, I also have no idea whether any of those three would be a problem in practice.
Would definitely enjoy learning from any experiment with aluminum plate bonded to copper pipe that you do...
I am presently mulling over how to weave copper wire between fixed sections of 1/2” copper pipe such that I will not be having to “pull it all through” each time around, ot “push the whole roll around” each time.
I am thinking I may go with taking straightened lengths of wire and pressing a “U” in where it will contact each pipe, then I can alternate them on both sides of the rows of pipe without having to do any “weaving”
It should be easily cleanable with a brush that way.
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Post by coastalrocketeer on Mar 15, 2019 17:04:27 GMT -8
One thing to think about is how much water, to what temperature and how quickly you want to heat it. What I mean is from my experience heating water takes allot of heat input and you need to consider how efficient you want to go. Whats the point if you spend 8 hours heating just enough water to take a bath? here is an example for you; I heat my greenhouse with water. I have a 330 gallon heat battery in the middle of the green house, a 55 gallon insulated tank that is a central heat exchange. I also heat grow beds with 1/2 poly tubing. I heat with a rocket mass heater with 25 feet of 3/8 copper coil directly above the heat riser inside the barrel. It gets 1000F+ and above flue gas direct heating. I have a second coil in a bell thats 20 feet of 1/2" copper that gets direct 300F-400F flue gas. They are open systems on both ends and have some drain back when or if the pumps stop. (It is a test setup and not what I would consider safest yet) donkey32.proboards.com/thread/3473/mini-rocket-forced-induction?page=2Point is, I have run this thing for 10hrs with top barrel temps around 950F and can get all the water up to about 100F. So what am I trying to say? From my experience it takes a ton of heat to warm up water. Now granted there is heat loss while I am warming them up but still it takes forever. I would like to be able to get the water up to 120F in about 3 hours so I am going to resign it with much more copper surface area and insulated bells trapping heat around the coils and see what happens. Not sure if this is reasonably possible. Bare copper coils make good water to water heat exchangers but poor water to air heat exchangers as they lack the surface area for the air side... the ones that go in A/C systems have lots of aluminum fin area for the air side. My idea is to take the coil and solder on scraps of solid 10 and 12 gauge copper electrical wire I have laying around on... to increase the air side surface area. I will have the coils spaced and have the wire run from each one to next, wrapping once or twice around each as it goes. This sound give better conduction on the air side I’m betting you are making PLENTY of BTU’s to get your desired temperature rise in that tank, but you’re only collecting 5-10% Pressure release valves on BOTH ends of each “hot zone” collector, with piping to carry any steam off in a safe direction would be prudent for anyone experimenting thus.
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Post by coastalrocketeer on Mar 15, 2019 16:45:28 GMT -8
I never said for fact that the circulation side was closed... to quote myself: "As I recall,the circulating side was a completely closed system". Again, this is aomething I haven't laid eyes on in 30 or so years, so give me some leeway here ok? Sorry, gonzo... I responded to that after reading another few posts and wasn’t saying what I said to say “that is wrong” so much as to impart what little I remember of what I’ve read about thermosyphon systems, and my own logical deduction that they CAN have an open tank, but only as the highest point in the system. (Had to think about that some when considering how to get hot water to and from my (at this point theoretical) open top “radiator barrels” from my “open top” rocket heated tank, sitting at different heights, inside and outside my structure to heat.) I realized that I will have to pump cold water uphill from the radiator barrels to the heated tank and let it return through an overflow on the tank... otherwise the barrels have to be sealed for a pump at the open heated tank to push water out and have cold return uphill... My apologies for both mis-remembering and misquoting your words, AND for having left you feeling attacked in any way, as that was not my intent at all. My response was intended purely in a similar intent to yours for sharing of our own notions, reasoning, and logic behind them for the mutual educational experiences. Thanks for being so gracious in your reply.
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Post by coastalrocketeer on Mar 15, 2019 0:33:27 GMT -8
whoever said it earlier... that a thermosyphon system has to be closed...
I believe that is incorrect.
For a thermosyphon to work, a couple of rules I know...
The tank HAS to be higher than the heat source...
tubing diameters need to be significantly larger than in actively pumped systems due to the low motive forces involved (more so the larger the heat input in relation to water volume in the pipes.
I do believe the tank CAN be open, but ONLY as long as the top of it is higher than any other water filled part of the system connected to it.
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Post by coastalrocketeer on Mar 15, 2019 0:27:04 GMT -8
In a tiny house, an emptyable 55 gallon drum or two inside the insulated structure could provide a direct radiative thermal mass that you empty when moving from place to place.
Filled wirh 50 gallons each, they would store 880 pounds of water, and I bet well heated would keep a tiny house warm for days after a charging.
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Post by coastalrocketeer on Mar 15, 2019 0:14:29 GMT -8
It is however, a good example of why cob, clay slip and sand mortar and the like are so lovely to build with, ESPECIALLY with experimental designs. Pull it apart... Break up cob with hammer, wire brush off clay sand mortar, rehydrate, rebuild.
It’s that easy!
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Post by coastalrocketeer on Mar 12, 2019 18:59:08 GMT -8
Need some finished photos when you get there, because this is the kind of stove to convince many peoples significant others... ;-)
When you have those, there is a “finishing and finished” thread somewhere for showing off gorgeous completed builds like I expect this one to be.
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Post by coastalrocketeer on Mar 9, 2019 12:27:33 GMT -8
I suspect that downdraft being able to run “cleanest” has to do with it being easier to achieve the 3 T’s to completion when forcing the combustion gas stream to go opposite the direction that it’s freshly heated gasses (and their embodied heat) wish to travel, and thus creating a super concentrated heat zone where the extreme temp shortens the time requirement sufficiently, in a zone where there is also sufficient turbulence induced.
This thought would make sense with the results seen with the latest iterations of Peter’s DSR II design, concentrating heat absorption in the zone immediately before the restriction, (especially the roof and tops of the walls, absorbing and re-radiating heat from those gasses in their hottest state) and inducing turbulent mixing at the same time.
My expectation is that a “top of the box” restriction will always perform better than the same restriction at the bottom of the shoebox, and that the smaller surface area in this extremely heated zone, will balance with sufficient space for mixing time to an optimum balance... too much surface area/volume/uninsulated mass in this zone will greatly reduce temps achieved and cleanliness of combustion, while too little surface area, distance traveled, and thus mixing time will also reduce cleanliness of combustion.
Bear in mind that I say all of this knowing little to nothing about down-draft combustion systems and their design, so it may not be relevant to them at all, and additionally, I may be entirely off base on any or all of it... just a notion/hypothesis, waiting to have holes shot in it.
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Post by coastalrocketeer on Mar 9, 2019 12:11:36 GMT -8
I am planning to do a similar design, batchbox feeding outdoor thermal mass, but with an open water tank at the top of the masonry bell, with a few layers of R-15 rock wool insulation around and above that masonry bell and water tank sides and top, and all inside a shed built of metal framing, siding, and roofing.
Water from the heated tank will be cycled to/from 55 gallon “mass” drums in various rooms of the house directly by 12v pumps, and a coil of copper in the tank will feed our DHW tank either pre-heated, or fully heated H2O, depending on the temps in the rocket heated tank.
Each 55 gallon drum will hold about 450 pounds of H2O as thermal mass, and act as a giant radiator. If they last a couple of years before rusting out that will be fine, as I can easily monitor their condition, and get new barrels cheap.
Smaller 15 gallon barrels in each room could work for a smaller structure like yours, and give you the mass storage, slow release effect.
The main heated tank could be right in your largest space, with the cob/masonry mass in the crawl space insulated, and the heat lost through the top would be lost into your home...
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Post by coastalrocketeer on Mar 9, 2019 11:55:42 GMT -8
This is true based on both the water issue mentioned by vortex, and the fact that it keeps the manufacturer from having to honor a warranty for anyone but professionals and tradespeople, and industrial users, who have the ability to conduct controlled initial firing to the specification.
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Post by coastalrocketeer on Mar 7, 2019 10:19:28 GMT -8
They both are rectangular and burn wood... that’s about it...
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Post by coastalrocketeer on Mar 2, 2019 11:03:16 GMT -8
Nothing about doors in my comment.
By baffle, I meant your added obstruction (circle of blanket on sides and bottom of upper box, that I too thought was a strip rather than a circle initially)
It is a U on the bottom and up the sides of the chamber now, and I was wondering what it would do if you flipped it “upside down” to cover the TOP and sides of the chamber, in rougly the same area of the box between inlet and exhaust.
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Post by coastalrocketeer on Feb 28, 2019 13:32:22 GMT -8
Interesting... might just be the lighting conditions/camera settings but it looks more yellow and less orange.
How about a test with that baffle around the sides and top with the bottom open? Interested to see if there is a positive or negative difference.
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Post by coastalrocketeer on Feb 27, 2019 21:50:58 GMT -8
Thanks for the answer and update!
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Post by coastalrocketeer on Feb 27, 2019 13:36:52 GMT -8
Hey WJ... hope all is well with you. Have you had any more chance to try this system out?
One Q I had... is there no secondary air in this system? I may have missed hat info in the thread. If so, sorry to ask the already answered.
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