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Alcohol Stoves

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    • sputtering was maybe the wrong term. Too much vapor pressure is more like it, pushing the flame further away from the jets. Opening the jets solved that with the tradeoff of a slightly rich burn (a little bit of orange here and there) ... perhaps now it is sputtering? I'll observe more closely.

      The Cuervo cans are a better fit than v8 cans.
      Maybe half the gap of what a v8 can produces.
      And from briefly looking in the store, the Cuervo cans are better than red bull cans.

      The fosters can is aluminum and perhaps a thicker material than standard. I can get my micrometers out to check.
      With it being double walled though, it seems to be pretty sturdy and up to the task. Once it gets banged up some I'll have a better idea of how sturdy it actually is.



      I'm on my third one. :)
      Cuervo cans seem to piss a stream when scoring through, but nobody told me that v8 cans pop in half without warning and soak the kitchen. Lol. My wife thinks I'm nuts.

      The post was edited 1 time, last by Klonkish ().

    • Klonkish wrote:

      sputtering was the wrong term. Too much vapor pressure is more like it, pushing the flame further away from the jets. Opening the jets solved that with the tradeoff of a slightly ruch burn (a little bit of orange here and there)

      The Cuervo cans are a better fit than v8 cans.
      Maybe half the gap of what a v8 can produces.
      • And from briefly looking in the store, the Cuervo cans are better than red bull cans.


      I'm on my third one. :)
      Cuervo cans seem to piss a stream when scoring through, but nobody told me that v8 cans pop in half without warning and soak the kitchen. Lol. My wife thinks I'm nuts.
      Wives just don't understand us
      Sometimes you will never know the value of a moment until it becomes a memory.
      Dr. Seuss Cof123

    • Take a look at Birdbrain's posts. He used a conical wind screen, and said the secret was to have plenty of ventilation at the top. That might keep things a little cooler around the burner. Or try a heat reflector disk around the top of the stove. Or wrap fiberglass insulation around the side of the stove. Wrapping aluminum foil around the fiberglass and tucking in the foil at the top (between the burner and the fiberglass) should protect the insulation from spills and minimize convective heat transfer through the fiberglass.

      The burn rate of the CHS depends on the number of jets, the size of the jets, the number of creases, the height of the burner, and the diameter of the hole at the top. I use the smallest hole in the top which contains the hole left by the pop tab, while still being centered. For a given number of jets and size thereof, the other factors will influence the fuel vaporization rate and the pressure at the jets.

      The burn rate also depends on the diameter of the can, but I don't expect you will find something smaller.

      The post was edited 3 times, last by WanderingStovie ().

    • Klonkish wrote:

      Thanks!


      Re: hot after a burn
      I'm not too concerned either but I do worry about thermal expansion/contraction affecting the epoxy seal, as well as the heat degrading the epoxy itself.



      I find it very reassuring that we have the same pot and similar boil/burn times!



      Re: nesting pot stand, narrow diameter, instability ---
      I have to say, this configuration so far seems to be far more stable with this pot than a typical top mounted canister stove arrangement (pocket rocket and better in terms of typical three legged pot supports)


      ...that's on my kitchen counter anyways; I haven't field tested it on uneven dirt. Haha!


      It seems like any tendancy to tip/shift is kept in check with the portion of the stand that nests into the heat exchanger. That, and the fact that it self centers the top heavy pot is a pretty big contributor I think.


      If it says anything, keeping the stove centered in the stand has been a far bigger concern than worrying over pot stability. And a solution for that is in the works -- the quick and dirty fix so far is three small strips of can material rolled into coil springs to self center the stove inside the stand.



      Re: lighter pot
      My Foster's can pot stand started life as a lightweight boiler pot... It never made it out of the house! The XTS pot is plain and simple worth the weight to me -- I'm always on a trip with atleast two adults, and quite often 2-3 adults and two kids. The volume and weight are completely worth it to me.


      Re: thermal feedback
      Somehow my boil times and fuel consumption didn't change. I am guessing that with the stand/screen it's somewhat choked and running cooler initially before it eventually ramps up... somehow I hit a balance where there seems to be no measurable difference in time or fuel for a 2c boil vs open air. Weird.
      A proper temp/time plot for the two configurations would be interesting --- they start and finish the same, but the rest of the story is certainly different. And that matters, considering that for coffee/etc a full boil isn't the goal. I imagine that for a warm beverage or any other non boil scenario one config is better than the other.
      Nice build - those are not easy to make. It looks like you cut away more of the can top than others here including myself have. That makes it bloom faster and run hotter.

      Regarding JB Weld, I have not had a problem except near or above air inlet holes in a chimney stove, not the type of stove (CHS) that you are building. When it gets too hot, it puffs up and turns black and brittle. If temperature becomes a problem for the epoxy, you could try one of their later products. jbweld.com/collections/8297/products/j-b-extremeheat

    • I'll be playing with aperature next.

      Today I built a cone. The pot stand and screen combo was clearly suffering in windy 40-45f conditions today. I was only hitting 140f on two cups of 65f water and 15ml fuel.

      With the cone in the same conditions I hit a boil 10 or 15 seconds before flame out.

      I'm getting there.....
      Images

      • 20170406_205350.jpg

        37.82 kB, 338×600, viewed 417 times

    • There are coatings on the inside and outside of aluminum cans that smoke when hot enough. I remove what I can with a rotary wire brush and steel wool. There are very good reasons (methanol, carbon monoxide, fire, leaks, spills, explosion) not to use an alcohol stove indoors, but removing the coatings may avoid setting off a smoke detector.

      Some coatings change the flame color. Remove the coatings if you rely on flame color during testing.

      The post was edited 1 time, last by WanderingStovie ().

    • Klonkish wrote:

      sputtering was maybe the wrong term. Too much vapor pressure is more like it, pushing the flame further away from the jets. Opening the jets solved that with the tradeoff of a slightly rich burn (a little bit of orange here and there) ... perhaps now it is sputtering? I'll observe more closely.

      The Cuervo cans are a better fit than v8 cans.
      Maybe half the gap of what a v8 can produces.
      And from briefly looking in the store, the Cuervo cans are better than red bull cans.

      The fosters can is aluminum and perhaps a thicker material than standard. I can get my micrometers out to check.
      With it being double walled though, it seems to be pretty sturdy and up to the task. Once it gets banged up some I'll have a better idea of how sturdy it actually is.



      I'm on my third one. :)
      Cuervo cans seem to piss a stream when scoring through, but nobody told me that v8 cans pop in half without warning and soak the kitchen. Lol. My wife thinks I'm nuts.
      I think most people empty the can before scoring it.

      I think your results are quite good for burning methanol. Ethanol has more heat per ounce, so KleenStrip Green may give you better numbers.

      You and OMO are using heat exchanger pots. Are the fins close enough together to quench the flame? If so, you probably want the flame to not quite touch the fins for optimum efficiency (unless unburnt fuel ignites after it passes between the fins, and the heat is absorbed by the side wall of the pot). I use a kettle without fins, so I am just speculating.

    • odd man out wrote:

      Yes, I know it isn't UL. My reason for choosing this pot was as follows:

      I wanted non-stick coated Aluminum, about 1 L (I cook in my pot, didn't feel like paying for Ti)
      I wanted a pot with a height:diameter ratio = 1:1 I didn't like tall narrow pots for cooking in and I feel I get more efficient and powerful performance with a wider bottom. With a wide short pot, the relatively large surface area will cool faster and be heavier for the same volume. a 1:1 H:D ratio gives the smallest surface area for a given volume.
      I like the handles high up the side so they are not too close to the flames. I'd rather have handles than a pot gripper.
      Looking around I found few pots that met these specs. The heat exchanger was a bonus. They make the same pot without the heat exchanger. I thought about that one. Maybe some day I will get my hands on one and get a real measurement of its effect on efficiency and power. This pot has a silicone lid, which is relatively heavy. You could shave a few grams by fabricating a lighter option. I don't recall the mass of just the lid. I will weight later and post.

      I have seen the CHS stoves. I may start playing with those for fun. The link you posted had minimal instructions. Is there a better one?
      I used geometry and calculus to derive a more general result for minimizing the mass of a cylindrical container with a given volume, assuming the bottom and sidewall have the same uniform mass per unit of area, but the lid has a different uniform mass per unit of area. Letting K be the ratio between the masses of the lid and the bottom of the container, the total mass is minimized when H = (1+K)R, with H being the height and R being the radius. If there is no lid, then the height equals the radius. If the lid is the same material and thickness as the container's bottom, then the height equals the diameter, as you have pointed out.

      Minimizing the area minimizes the fuel wasted heating the pot, but a larger area lets more heat be captured by the container and water, and less heat escapes to the atmosphere. For those of us not using a pot with a heat exchanger, the geometry of the pot is important, and efficiency seems to be better for pots where diameter exceeds height (my Ketalist) or height exceeds diameter (can pots), so long as the exhaust remains in contact with the bottom and sidewall. Some burners only send flames up the side of a can pot. Heat is transferred to the bottom of the can pot by fuel vapors and contact with the burner, and the thick aluminum bottom of the can pot efficiently spreads the heat transferred by contact with the burner.

    • meat wrote:

      I get the geometry part, but where does the calculus part come in to play...I don't know calc.

      While it is possible to write a formula in calculus to describe a three dimensional object there have to be easier ways to do it. I hated that chapter in class and I believe I have succeeded in forgetting how to do that. Thankfully.
      --
      "What do you mean its sunrise already ?!", me.

    • JimBlue wrote:

      meat wrote:

      I get the geometry part, but where does the calculus part come in to play...I don't know calc.
      While it is possible to write a formula in calculus to describe a three dimensional object there have to be easier ways to do it. I hated that chapter in class and I believe I have succeeded in forgetting how to do that. Thankfully.
      thanks Jim, yup, not my forte.

    • I haven't used calculus in years. I calculated the surface to volume ratio using a spreadsheet. Write formulas for calculating surface area and height as a function of diameter for a given volume (only requires algebra and geometry). Then make a few hundred copies of the formula for slightly different diameters and plot area vs height/diameter ratio and yo find the minimum. It came out to close to 1:1.
      But even if it isn't the most efficient, I like that ratio as tall skinny pots are hard to eat from and wide short pot slosh and spill too easily.

    • meat wrote:

      I get the geometry part, but where does the calculus part come in to play...I don't know calc.
      First you need an equation for the area, expressed in terms of volume and radius (or height, but not both). Then you take the derivative of the area with respect to the radius (or height), set it to zero, and solve for the radius (or height). The derivative gives the slope at all points along the graph of area versus radius (or height). The slope is zero at the stationary point(s), which are local maxima or minima (summits and valley bottoms if you were hiking the graph). Thankfully, there is only one stationary point, and it happens to be the minimum.

      See en.wikipedia.org/wiki/Stationary_point

      The post was edited 2 times, last by WanderingStovie ().

    • WanderingStovie wrote:

      meat wrote:

      I get the geometry part, but where does the calculus part come in to play...I don't know calc.
      First you need an equation for the area, expressed in terms of volume and radius (or height, but not both). Then you take the derivative of the area with respect to the radius (or height), set it to zero, and solve for the radius (or height). The derivative gives the slope at all points along the graph of area versus radius (or height). The slope is zero at the stationary point(s), which are local maxima or minima (summits and valley bottoms if you were hiking the graph). Thankfully, there is only one stationary point, and it happens to be the minimum.
      See en.wikipedia.org/wiki/Stationary_point
      that's pretty neat.

    • meat wrote:

      WanderingStovie wrote:

      meat wrote:

      I get the geometry part, but where does the calculus part come in to play...I don't know calc.
      First you need an equation for the area, expressed in terms of volume and radius (or height, but not both). Then you take the derivative of the area with respect to the radius (or height), set it to zero, and solve for the radius (or height). The derivative gives the slope at all points along the graph of area versus radius (or height). The slope is zero at the stationary point(s), which are local maxima or minima (summits and valley bottoms if you were hiking the graph). Thankfully, there is only one stationary point, and it happens to be the minimum.See en.wikipedia.org/wiki/Stationary_point
      that's pretty neat.
      Will there be a test on this?
      "Dazed and Confused"
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      Take a kid hiking
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    • NoAngel wrote:

      meat wrote:

      WanderingStovie wrote:

      meat wrote:

      I get the geometry part, but where does the calculus part come in to play...I don't know calc.
      First you need an equation for the area, expressed in terms of volume and radius (or height, but not both). Then you take the derivative of the area with respect to the radius (or height), set it to zero, and solve for the radius (or height). The derivative gives the slope at all points along the graph of area versus radius (or height). The slope is zero at the stationary point(s), which are local maxima or minima (summits and valley bottoms if you were hiking the graph). Thankfully, there is only one stationary point, and it happens to be the minimum.See en.wikipedia.org/wiki/Stationary_point
      that's pretty neat.
      Will there be a test on this?
      I hope not.

    • WanderingStovie wrote:

      I'm trying two jets to see if I can get a fire tornado similar to Tetkoba's CHS. I am not sure it is visible, but the jets are near the inner wall, aimed horizontally.

      This one did not meet my goals. The jet angle is wrong, there aren't enough jets, the aperture is too big, and the jets should be at the top edge. There is too much thermal feedback, and too much vaporization in the bathtub.

    • Klonkish wrote:

      Hello everyone, first post here. It's a long one :)

      Great thread going here. Thanks to all of the contributors and creators for taking a huge amount of the guesswork out of stove building -- Extremely helpful to a novice like me!

      I'd like to hear some feedback and advice on how to do better with my next build.


      My first ever alcohol stove build/attempt:

      eCHS
      41mm aperature, 35mm tall, 18 creases, 6mm bottom tabs cut with scissors (no gap), 7x 0.7mm jets, 53mm Jose Cuervo can

      I'm using yellow Heet ($4.32 for a 4 pack at Walmart right now, $0.09/oz -- I think that must be a really good price??)

      I also built a pot stand and windscreen with a fosters beer can, top lid and entire bottom removed, cut into two sections with one section inserted into the other, and vented with three simple vents at the bottom.
      The can top section was inserted into another slightly shorter section of the can --- the beauty is the protruding can top section nests quite nicely into the bottom opening of my XTS boiler pot, ensuring it's exactly centered and with minimal interference, while the slightly shorter outer wall provides pot stability and extra strength at minimal added weight (see pics)

      I played with pot stand heights, noticing a huge difference in boil times. I settled on dimensions that would set my pot bottom (not the fins) right at about 35mm above my stove. I intend to do some more fine tuning with stand height and would appreciate feedback on desired /target heights.

      I noticed that with my stand/screen I get noticable increased thermal feedback about 50-75% through the burn, with the stove really picking up the pace. This seems to have had zero effect on boil time or fuel demand vs an open air arrangement.

      Another thing I've noticed, even running in open air mode, is that the stove is a bit hot to handle -- I can handle it, but it's fairly uncomfortable (I cook a LOT and have a pretty good tolerance to holding hot pans/etc)
      After a boil with the stand/screen --- no way. It's pretty hot.



      I started with 0.6 mm jets which performed well but had some occasional sputter and noise from a few of the jets.
      I enlarged to 0.7mm and the sputtering is gone but I've added some orange to the burn.
      However, boil times seem to be identical.

      I am reaching a repeatable 212f/100c boil with 2 cups/475ml of 60f/15.5c water right at the 4:30 mark with 15ml of fuel. Fuel runs out within 5-15 seconds. 70f/21c ambient temp.

      Bloom time is 6-7 seconds.

      I think I did pretty good, but can't help but think there's room for improvement.

      So..... where do I need to look for improvements? Jet angle? Jet size? Stand height? Bottom tab criticisms/suggestions?

      Also, I have a 95mm toaks 550ml mug/pot --- it seems like there's no way one of these stoves will ever be compatible with anything with a "narrow" diameter like this. Flames up the sides, scorching hot handles, etc. Am I right? Would a simmer ring do the trick? All I really need to do with that mug is warm up coffee/etc thats gone cold, not necessarily boil water (although that would be really nice)



      You will learn much more by reading Tetkoba's diary than you will by getting information second hand here. Chrome asked me if I wanted to translate to English. There are a few things that don't translate well, but I learned a lot. If you read some of my early posts regarding the CHS, you may notice my misunderstanding of the name Capillary Hoop Stove. I understood it to be a stove with a capillary hoop, but after reading the diary I see that hoop stoves came first, and the capillary action was a refinement thereof. Advice to increase the volume of the hoop to avoid "boiled bomb" pressure surges makes more sense when the hoop is understood to not include the portion of the inner wall where the tabs and creases are. If you use three walls, the two inner walls are close together, but the two outer walls can be much farther apart and provide the necessary volume to regulate the pressure. Whether you use two walls or three, the innermost and outermost walls must meet at the top with an airtight seal. To angle the jets, the innermost wall should be thick, or should have a 5-layer rolled rim like many cans. If you need an angled jet through a thin wall, back the hole with a blob of epoxy.

      The post was edited 1 time, last by WanderingStovie ().

    • And now for my next trick, I am making a low profile flat bottom CHS from the bottom of a 1 ounce (30 ml) Nivea can (2 1/4" OD, 1/2" height), the top of a can of liquefied cheese (2 5/32" OD), and the bottom of an aluminum beverage can (57 mm OD). This is a three-wall stove.

      My goal is a 2/3 fluid ounce (20 ml) capacity and a 1" (25 mm) height. I use the top 1" of the cheese can, with the nozzle and gasket removed, leaving a 1" (25 mm) aperture. Adding 8 holes of 1/4" diameter around the 1" aperture gives the equivalent area of a 1 1/4" aperture, which is hopefully enough to avoid damage to the stove from detonation or deflagration. If the burner does not bloom quickly, I will make the aperture larger, and the burner will be less than 1" tall after removing the 1" ID lip.

      I use the bottom 19/32" of the beverage can, with the 1 1/16" diameter domed portion removed. I drill 8 jet holes with a number 76 drill bit, angled to produce a tornado-like flame.

      I use an 11/16" wide strip of the sidewall as a capillary band around the top of the cheese can. This band only contacts the lower 1/2" of the top of the cheese can, but the extra 3/16" of height should limit vertical movement. The ends of the band are secured with a dovetail joint.



      Helpful construction hints:

      • Drill the jet holes after the JB Weld sets.
      • Make the eight 1/4" holes close to the lip of the 1" diameter hole.
      • A 1/4" drill bit works best, but a paper punch can be used if you restore the conical shape afterwards and use more epoxy.
      • Stretch the outer piece over the bottom of the Nivea can before pressing it down over the top.
      • If you need to separate the outer piece from the Nivea can, open needle nose pliers braced against a washer just under 1" in diameter to avoid denting the bottom.

      The post was edited 5 times, last by WanderingStovie ().

    • odd man out wrote:

      propersoda.com/shop/hop-soda

      Here's a new can to use for an eCHS stove. It seems to be pretty much the same as a V8 or Ocean Spay Sparkling Soda Can, but it has a plastic label the peels off to give a "naked" can with no work.

      Haven't tasted it yet, but it got good reviews from the lady at the beer store.
      I found a 500 ml can with a peel-off plastic label at an Asian grocery. It should work for making a naked penny stove. Wei Chuan Kiwifruit Drink with Pulp, UPC 072869120625.

    • I widened the aperture to 1 5/8" (41 mm) and left the jet holes at #76 (0.5 mm). The jets ignite ten seconds after lighting the bathtub. There is less thermal feedback because the jets are not hitting the inner piece. The jets are not as noisy, but the flame tears away from the hole (leaving a gap between the hole and the flame). The burner is now 15/16" (24 mm) high.



      You should be able to extinguish the flame by placing the pot directly on the burner, and use a suction bottle to easily recover most of the fuel by slightly tilting the burner to one side. Wear appropriate gloves or wait a couple minutes for the burner to cool before touching the burner. Do not operate burner in contact with textiles, plastic, or other heat sensitive materials.

      The post was edited 5 times, last by WanderingStovie ().

    • odd man out wrote:

      WanderingStovie wrote:

      odd man out wrote:

      I have seen Japanese tea at World Market but they came in steel cans. They deffinitely would not work.
      Why not?
      I had my hands on one once. They are thick and heavy. Hard to cut and work. I would think they large difference in thermal mass would make them malfunction. But I'd love to be proven wrong.
      I found the perfect A=B (outside diameters of rim and sidewall are identical) can for making the eCHS, but it is steel except the top closure. I hope to prove you wrong shortly. Even better, the bottom is flat where aluminum cans would be concave (as seen from the outside), so the fuel capacity is greater for a given height. It will still need tabs at the bottom to draw up the last ml of fuel. The top closure is recessed deeper than that of aluminum cans. I don't know yet how that will affect performance.

      ITO EN (North America) INC. Jay Street Coffee Coffee Shot 6.4 FL OZ 190ml UPC 835143010810

      The post was edited 1 time, last by WanderingStovie ().