Alcohol Stoves

4 ounce Mesri red curry paste, nine 3/64" holes (angled for vortex)
Febreze(R) air freshener can, outer cylinder nine 1/8" holes, inner cylinder 9 creases ending at 1/8" holes in outer cylinder

I ram swaged the outer cylinder over the top and bottom of the air freshener can, using water soluble lubricant. Then I added the creases to the inner cylinder (can bottom). The top of the outer cylinder is scalloped to minimize heat loss to the pot, and vent fuel vapors originating inside the inner cylinder.

I'm hoping most of the fuel vaporizes between the two cylinders, passes through the creases, then the 1/8" holes, and finally the 3/64" holes.

put over pasta, it helps a little.

NoAngel wrote:

odd man out wrote:

do you eat the cat food when making cat food can stoves?

in 2013 I met three sobos who called themselves "Dirty Mike and the Boyz" who did just that.They ate it on crackers like it was an hordierve. They were a trip.

Here are "The Boyz" eating their cat food

My latest stove works. I boiled water and made ramen. It takes too long to bloom and it is too heavy, but enlarging the center hole should correct both.

put over pasta, it helps a little.

Like fish food, does cat food mean it's made of cats?

cat food - it's on the menu at the flop house where entitled hikers go when they get old.

meat wrote:

Like fish food, does cat food mean it's made of cats?

Is there Southern Comfort in your comfort food?

only when me mum makes it!

Reminds of the old Marketing lesson from Africa on why Gerbers couldn't sell any baby food there. They looked at label, and since they were not cannibals, were not interested in it.

The flash point of ethanol is 62F. The flash point of isopropyl alcohol is 53F. The flash point of methanol is 52F. At 13F, I lit methanol Heet with a lighter, but it did not stay lit. After I warmed the stove (with fuel) in my hand, I got it to stay lit.

I did an alcohol stove test at 5 below zero F and the stove worked fine. I lit the stove by dropping a wooden kitchen match into it. Perhaps that was enough heat to get it going.

The "dip a twig and light" method also works.

I want to try acetone, with a flash point of -20C (-5F) and a heating value nearly as good as ethanol.

The difference in heating value between methanol and ethanol, and the various formulations of denatured alcohol probably account for some of the differences in power, efficiency, and burn time reported here and elsewhere.

Probably true. I have some pure methanol (HEET), denatured alcohol (50/50) and denatured alcohol (nearly 100% ethanol), but never bothered to test the performance of one fuels vs another.

I wonder how ethyl acetate would work? It's flash point is 25 F. BTW, if you try that and die from toxic fumes or explosions or fire, don't blame me.

I saw a video of acetone burning with a yellow flame. Yellow flame = incomplete combustion, soot, and wasted chemical energy, but if it is easy to light, I may try blending it with methanol.

I hope to try a silicone rubber gasket in my next alcohol stove, with the same type of can (curry paste) for the fuel reservoir. The pot is supported by part of a smaller diameter can bolted atop the fuel reservoir. A silicone rubber washer / gasket seals and insulates the pot support, fuel reservoir, and capillary fuel vaporizer.

The inner diameter of the gasket matches the outer diameter of a small aluminum fruit juice can. The gasket is pushed over the juice can with the help of lubricant. The lubricant is washed off. The top and bottom of the juice can are removed. A rectangular piece of aluminum beverage can side wall is used as a capillary hoop. Tabs are gently folded outward at the top and bottom to join the ends of the capillary hoop and maintain its cylindrical shape. The juice can is inserted into the capillary hoop. This forms the capillary fuel vaporizer.

Jet holes are drilled and angled into the top of the fuel reservoir. The fuel reservoir is turned upside down. Three small screws are inserted into holes in the fuel reservoir, with JB Weld around the heads. The fuel reservoir is left upside down with the screws hanging down until the JB Weld hardens. The capillary fuel vaporizer is inserted into the fuel reservoir. Holding the pieces upside down prevents the capillary hoop from sliding off the juice can. Matching holes in the gasket and pot support slip over the screws, and nuts are added. The top of the fuel reservoir is thin and flexible, which should make it easy to align the screws with the holes in the pot support even after the JB Weld has hardened.

Aluminum has more than 1000 times the thermal conductivity of silicone rubber (205 W/mK vs. 0.14 W/mK). I hope the gasket prevents a potful of cold water from interfering with fuel evaporation and extinguishing the flame. I also hope the low thermal mass of the capillary fuel vaporizer and the insulating property of the gasket make the stove bloom faster.

If you haven't looked at Zen Backpacking Stoves in a few years, you might want another look. I see good new information there.

I burned some acetone in my alcohol stove last night. I saw vigorous boiling in the center, big yellow flames coming out of the center, and blue jets with yellow tips. I'm guessing the tip is yellow because the velocity is lowest at the tip, and therefore mixing with oxygen is lowest at the tip.

I also tried using a cellulose sponge inside a double-wall stove. It was slow to bloom, and the burn rate gradually diminished as the sponge dried up.

I cut the top off a Jumex can. The cap screws on and has a clear elastic gasket inside. I wonder if it is silicone, and how much heat it can take before failing. I should be able to JB Weld the steel parts from the Jumex can into a La Lecherita can, making a pressurized stove or a leak-proof stove that can be snuffed out and sealed with fuel still inside, similar in function to a Trangia spirit burner.

Yeah, if you blow your hand off, just know we're gonna talk about ya

I tried using a silicone rubber gasket cut from a Wilton baking sheet. The top surface cracked where it touched the steel 1/8" away from the jets. The jets burned the paint off the steel, so too hot for silicone rubber.

I like my alcohol burner to be as short as possible to minimize the size and weight of the pot stand and windscreen. For me, that has meant a burner with vertical jets and an open top, but the jets get fouled when I burn nasty things like fuel injector cleaner (as a last resort when I can't find a more suitable fuel). Therefore, I am testing a chimney stove with holes large enough not to clog, and no wick or capillary hoop to get gummed up. I will need a pot stand and windscreen probably at least an inch taller. The design is all aluminum except for a thin steel cap used to reduce the burn rate for simmering. Most of the designs I looked at had a one-inch diameter hole in the top through which all flame passes. I had to increase the diameter to one and a quarter inches. Some of the flame bypasses the top hole, rising between the inner and outer walls, once the burner warms up, until almost no fuel remains. To simmer, wait for this secondary flame to appear, and then drop the steel cap over the top hole.



To build this burner, you need the top of a twelve-ounce aluminum soda can and a three-ounce aluminum potted meat can. I used a cut off wheel to remove most of the pull tab on the potted meat, leaving the can unopened, and then cut the 1.25" diameter hole in the bottom. I removed the label, glue, and potted meat. I drilled 48 holes 7/64" in diameter 1/2" from the bottom. I removed the top rim from the soda can with a file, cut the height to 2 1/16", and punched six 1/4" holes centered 1 5/8" down from the top edge. I turned the potted meat can upside down, and pushed it into the bottom edge of the soda can top. I rolled over 3/32" of the bottom edge of the soda can top to keep the potted meat can from popping out.

The steel cap is roughly 1 3/4" in diameter. I used one end of a biscuit dough tube.

what's the burn rate (power) of this?

I have a kettle, a thermometer, a graduated cylinder to measure fuel, and a container to measure approximately 2 cups (473 ml) of water, but no pot stand yet. I should try pot stands of different heights to see what works best. I expect the kettle will interfere with the updraft, but possibly increase thermal feedback, making the stove burn richer and less efficiently. I hope to find a pot stand that holds the kettle 1.5 to 2 inches above the ~2" high outer edge of the burner, so I am off to look for three steel cans roughly 3.5 to 4 inches tall.

My subjective analysis suggests the burn rate is faster with a taller outer cylinder. I wanted a shorter burner and a shorter flame, so I reduced the height of the outer cylinder to what I reported above. I would like to further reduce the height of the burner and flame, but I would need a shorter inner can. I could cut up the inner can, but that requires joining two pieces of the inner can, which changes the thermal feedback and may increase the weight and thermal mass of the burner. I may cut vertical slits and fold the sidewall inward and upward, drilling the 48 holes below the folds.

Why 48 holes? The circumference of the inner can is 192 mm, or 48 x 4 mm. I may try a different inner can with thirty two 1/8" diameter holes, since 32 x 6 mm = 192 mm. Maybe I can reduce the diameter of the top hole and/or reduce the number of holes near the bottom of the outer cylinder.

you stovie guys are awesome! I just whip out the ka-nife and pop a bunch a holes in an old tin can, and call it good.

meat wrote:

you stovie guys are awesome! I just whip out the ka-nife and pop a bunch a holes in an old tin can, and call it good.

Dude. You left out the calculus ! For shame !

my bad!

2 cups = 473 ml water at 69.3^oF, 20 cc Heet (methanol), ~1.25" gap between kettle and burner, water vapor visible at 8:45, full boil at 10 minutes, burn out at 11 minutes.

The JB Weld is curing on my latest. I guess I'll call it a unijet.

It sure looks like you are doing some high quality work, good job.
But just how does that design work ?
There seems to be an outer wall, inner wall, and top. But what does that 3rd ring do and what's the hole in the tube for?
Inquiring minds want to know!

Thanks. The third ring hugs the inner wall with an average gap of 0.16 mm. The capillary action causes the fuel to rise higher on the outside than the inside of the inner wall, hopefully causing the fuel to be vaporized preferentially between the walls. The inner wall is directly exposed to flame inside the burner. Some heat is transferred to the outer wall, but the transfer is limited by the relatively loose fit and the JB Weld. Heat travels down the walls to vaporize the first fuel reached. The fuel vapor exits vertically through the single jet in the 1/8" diameter tubing at the center of the stove. The jet and the heat of the flame result in an upward motion at the center which hopefully causes air to be drawn downward into the six 1/8" holes around the perimeter. Those six holes direct the air at the top edge of the inner wall. Hopefully there is flame where the air meets fuel vapor inside the stove, and the flame heats the inner wall.

The chaotic nature of the boiling fuel causes liquid fuel to rise farther than capillary action alone would cause.

So the third ring is a capillary hoop, but this is not Tetkoba's CHS, and there is no tornado of flame caused by inwardly angled jets.

The top piece fits loosely, and is easily replaced to adjust the burn rate. Placed upside down, it forms a pot support. The stove is easier to light and the jet appears sooner with the top piece off. Adding the top piece reduces the burn rate and causes most of the fuel vapor to pass through the jet. In theory, jets produce turbulence, better mixing of fuel and air, and potentially more complete combustion and a hotter flame. Jets work better against a crosswind.

Thanks for the explanation.
Have you tried this kind of design before or is this the first go at it?

The tubing with a single central jet is something I haven't tried before. The top piece with a 1" central hole surrounded by smaller air inlet holes is a design I have seen before, but I don't remember where. Double wall stoves with an open top and jets are quite common, whether stoves made by Tetkoba and JSB, a Pepsi can stove, or a White Box stove. I have not seen others use the top of a potted meat can as an inner wall, and most people avoid steel cans. The outer steel can has an exceptionally thick domed base, and is quite heavy. I will probably try a flat-bottomed steel can to make the stove shorter for the same one-ounce capacity. That will save some weight.

I tested the stove without the JB Weld. I lit the stove several times with the top piece on, but the flame died out after a few seconds each time. I had to light it with the top piece off, wait for it to warm up, and then put the top piece on. That behavior is typical of stoves where the large top hole is too small relative to the height above the surface of the fuel. After all fuel burned, I waited for the stove to cool. When I touched it, it was surprisingly cool. Most other stoves with that much steel take much longer to cool off. That is probably related to why I could not light it with the top piece on.

I blew the top off twice this morning. The #61 drill bit made the jet hole too big. There was not enough chimney effect to have stable flames at the 18 air inlet holes (7/64").

If you need/want drill bits smaller than a # 60 try here

mcmaster.com/#standard-drill-bits/=170i8ga

and scroll down a little more than 1/2 way

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)

Very nice. I've made a bunch of eCHS stoves. I have been using them with an XTS pot for a few years now. Mine also are hot after a burn. I don't worry about it. I cut a circle of car sun screen as a heat reflecting insulated base. Your burn and boil times seem similar to mine.

Interesting to make the wind screen/pot stand nest inside the heat exchanger. Does that narrow diameter make for much instability? I went away from side burning stoves (cat can, bottle, etc) because of the narrow base. I had a habit of tipping my dinner. So many people go on about how great it is to not need a pot stand. I don't get it. Lots of advantages to pot stands. I used to use galvanized steel hardware cloth rings for pot stands.(before I developed an integrated stand/screen). I made one that was rediculously tall and then snipped off rows (0.5 in) until I found the optimum. I think mine is a bit taller than yours, but I think I drill my ets to point up more than most. I think it generates more convection up draft to have the flame higher above the stove, but in the long run I doubt it matters much. I am now using a cylinder of aluminum flashing for a windscreen/potstand. Its diameter is so the heat exchanger is centered on the stand -a wider base for the clutz. I haven't done much testing or building recently. I got the system to do everything I wanted and quit. I sometimes wonder on how to make it lighter with a lighter pot, but I cook in my pot so the bomb proof anodized XTS is pretty nice and for me worth the weight for now.

I have on occasion heard what I thought was some thermal feed back making the stove ramp up, but not often. Having a wider taller pot stand would minimize this, I would think.

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.

are Foster cans steel or Aluminum? I would think an Al can would be too flimsy, but then I thought Foster's cans were pretty beefy.

I've been using the same stove for a few years now and not seen any segregation of the JB Weld. And that seam is right by the Jets so it will get hot no matter what.

My boil times were a bit faster but I was starting with warmer water. I think my stove may run a bit hotter too. Congrats on making all the right measurements. Most people don't.

I have done tests with this stove to measure heat output vs time for the length of the burn. It is almost perfectly linear. Knowing this can simplify your calculations. The burn length as a function of fuel load tells you rate of fuel consumption (stove power). Boil time will be a function of stove power and how much of that energy is delivered to the water (efficiency). If you multiply fuel load times boil time and divide by burn time, you will get a good estimate of fuel burned to boil (efficiency). If you want to get fancy you can use temp change and water volume to Calc calories.

I was hoping the Jose Cuervo cans would let you build the stove without epoxy. I guess I was wrong. How close is the fit between the rim and the sidewall?

Regarding sputtering (droplets of liquid fuel ejected from jets seen as yellow sparkles in an otherwise blue flame), I would guess it would help to have the jet hole as far from the inner wall as possible. Roll swaging the inner wall inward just below the rim may help. You could make the number of creases a multiple of the number of jets, and line up the holes with the creases. You may want to make the crease deeper and wider near the hole. Or you could shield the holes with a ring of additional material so that liquid fuel could not take a direct vertical path towards the jet holes, but fuel vapor could still exit via an indirect path.

here is my simple way to center the stove. Get a disposable Aluminum pie plate with a dimpled surface. Cut a circle just smaller than the inside diameter of the pot so it stores on the bottom. Use this as you heat reflector base. Then get can the same diameter as the stove and use it to pound an impression into the Al circle . Make another impression the diameter of the pot stand. Then everything sets on top of the all lined up.