My Latest Alcohol Stove Design

Does the stove have levitational abilities?

I like it :)

I love it. I'm a big fan of using mousse cans for alcy stoves. Nice thick aluminum for durability but still relatively easy to work with. My first and only myog stove used one.

Nice, the flame pattern looks nice for small diameter pots. Does a pot of cold water placed on the stove cause it to reduce flame size?

DY
Adventures In DIY Stove Making

Joining the chorus, I like it too. Those appear to be reasonably small holes around the side, are they 3/16" or less? Also looks to have quite a bit of fuel capacity?

Hey guys, thanks for the props.

@Zelph: Flame pattern is pretty good with larger pots too. Here is a picture of the Ramjet XUL with a Grease Pot. The flames only get smaller for a few seconds when a pot is put on the stove. The scalloped top edge of the stove has very little surface contact with the pot, so conduction of heat from the stove to the pot is minimized.

@Delmar: The holes are drilled with a #39 wire gauge bit (.099"), so they are a bit bigger than 1/2 the diameter of a 3/16" bit (.1875"). Maximum fuel capacity is about 45 ml, for a total burn time of 25+ minutes.

> The holes are drilled with a #39 wire gauge bit (.099"), so they are a bit bigger than 1/2 the diameter of a 3/16" bit (.1875").

Interesting! I had read somewhere that on low-pressure "super cat" style stoves, holes under 3/16 inch were hard to keep lit; not the case for your stove I take it? Let us know how it takes a breeze. I like the 25 minute capacity, and you've an interesting method for keeping the stove hot. On castles and flashlights, that design is called "crenellated."

BPL used to sell something similar.

http://www.backpackinglight.com/cgi-bin/backpackinglight/ts_side_b_alcohol_stove.html
I might make one …

Delmar,

Crenellated is a good word. Better than the "castellated" I had thought of.

I have not had any problem with the small holes staying lit. The trick is getting them lit as you transition from updraft to side jets. The stove needs to warm up for about 30 seconds to be hot enough to start boiling the alcohol and pressurize when you set the pot/can down on it. Unlike the BPL kit that Franco referenced, this one will not stay lit inside if you put the pot down too soon.

Is there any no-pressure or low pressure alcohol stove that works well in a breeze? All the ones I have tried and made are very sensitive to air movement. I can see where a fully pressurized stove would make a difference, where the velocity of the jets is high relative to the wind speed. But if there are good designs for wind-resisting low-pressure stoves out there I'd love to know about them.

Dan?

I figure a good, big windscreen is what really makes the difference in a breeze. That's what I'm going to work on next. I have an idea about hole placement I want to try on one of my conical windscreens. Didn't BPL or someone do some tests and establish a testing protocol for performance of alcohol stoves in wind, using a fan?

Franco,

Wow. Can't beat the weight and compactness of that BPL set up! Did they ever publish any performance information?

"Can't beat the weight and compactness of that BPL set up!"

I have one almost identical to this that I made a few years ago. For the alcohol container, I used a plastic 35mm film can, so it is shorter than the screw-cap bottle.

However, Esbit is the best for this kind of rig. There is virtually no fuel container weight, and it doesn't leak.

–B.G.–

David,
I only remembered the look of the stove.
Here is a nice video clip on it with some details :
http://www.youtube.com/watch?v=3XCtF3k-kNM

When I was playing with the White Box stove and some of my own, I could get the flame to blossom a bit faster by slowly lowering the pot onto the stove.
From memory this was a bit hit and miss but you may want to try it anyway.
I made a very similar design to yours using a tuna can but in the end I preferred the 12-10 burner.
The Caldera Cone does work vewry well in the wind but I think it is the cone not the 12-10 that matters.

I thought the "slowly lowering the pot onto the stove" trick was effective because it reflected heat back to the stove from the bottom of the pot. Somewhere I read you can speed up the warming of the stove a bit, by keeping your pot an inch or so off the flames during the pre-heat.

Elsewhere I've been told that painting the stove black with hi temp paint, also helps.

And lastly, there may be some effect of how far above the alcohol level, the holes are. I recently went from a two-rows of holes "supercat" design to a one-row of holes "simmercat" design. Instead of taking 30 seconds to preheat, it takes 60! The only difference I can think of, is that the holes in the new stove are a half inch higher than previously. This is a wild guess, and may be incorrect.

Regards compactness on a low-pressure side vent stove: get it too small, and you're in for a tippy setup. The BPL stove pictured above is nifty, but I'd not want to try and balance my pot on it. I'd prefer a fatter stove.

I have the one that BPL used to sell but I couldn't remember the name of it,thanks for posting it Franco

HERE is the MYOG instructions for the Gram Weenie.

I have found that the pressurized jet type stoves don't work well in wind, but then I've also found that most alcohol stoves don't work well in wind.

The one exception that I have found is the Zelph Super Stove type.
Something about that shape keeps the flame under the pot.

I have used the more popular Zelph Starlyte, but haven't had enough experience in wind to have an opinion.

@Zelph, how do your various stoves compare wind wise?

As a low-pressure side jet stove the pot is supported directly on the stove. Will boil 2 cups of water in a Foster’s can in 9 minutes using just 15 ml of fuel. (Boil times based on camping stove industry standard of 70* F water, air and fuel at sea level.)

As a no-pressure updraft burner, the pot is supported separately about 2″ above it. I use one of my conical windscreens with two stainless steel stakes through it. Will boil 2 cups of water in a Foster’s can in 6 minutes using 20 ml of fuel.

That’s interesting that it takes about 30% more fuel in updraft mode. It must be that contact with the pot is limiting the air inflow which makes it burn more slowly and efficiently.

Were windscreens used in both cases?

HJ
Adventures in Stoving

@Zelph, how do your various stoves compare wind wise?

Steven, here is one that I found and I’ll be back tomorrow with the StarLyte burner one that shows it burning in the wind and -13 degrees in cold Minnesota. All of my wick stoves perform well in the wind. The Cobalt Blue Soloist should do well also (low pressure).

Budlite Super Stove in the wind and cold

DY
Adventures In DIY Stove Making

Re: "That's interesting that it takes about 30% more fuel in updraft mode."

It does make sense though. Unless all the heat from the bigger flame can be contained, it is going to shoot past the pot faster than it can be absorbed.

I have always leaned towards the slower burning stoves when I am concerned about weight.
I find that shallower wider pots are more efficient as well.

The Jetboil and other systems overcome this by adding heat exchange fins to help absorb much of this heat as it gets forced past the pot.

I wonder how many stove geeks have experimented with UL heat exchange fins on typical Heineken, grease pot and the many titanium backpacking pots?

I haven't been keeping up to date on the bplite forum. There seems to be a lot designed for canister stoves, but not much for alcohol.

I did some experiments about 10-12 years ago with heat exchangers. I was looking to maximize heat transfer between a flame (any kind of stove) and the water inside.
Basically, it turns out that by the numbers, there was no difference between using a larger pot (8" diameter) and a smaller pot (4.25" diameter) with a heat exchanger. To the heat transfered into the water, they both looked like an 8" pot for heat transfer purposes.

The smaller the flame, the less efficient the heat transfer becomes, well to a degree, with heat exchangers. Again, it looks like the heat must first warm the exchanger for any usable heat transfer. And, for normal pots, a small flame allows for long heating times. This also allows long radiation times for the heat to escape the pot/water. I could boil water (210f for my purposes due to altitude) but it took about 15-18 minutes. With a blanket around the pot(3/8" foam cozy,) this was cut to 12min and about a 1/3oz of alcohol (.28oz average for 5 runs.) But it sort of ruined the foam. I tried this without a heat exchanger and got nearly the same results about .30oz per boil average. The heat exchanger wasn't doing anything significant. A little more playing around showed that the HE was actually working on excess heat. IE, you need a larger flame to make it work. The fuel penalty was slight, only about .32oz per boil(about a gram difference) for the reduction in time(about 10min,)about 40%.

Anyway, the heat exchanger and cozy only cut the heating time, not overall fuel usage…it was still about a 1/3oz after adjusting to a new burner. I concluded that this was soo close to minimum, that it really didn't matter. 1/2oz (~14-15g) for 2 cups was about as good as it gets in the field, though. For comparison, my WG stove gets about 10g/Liter under the same conditions, by spec (11 liters for 4oz.)

Anyway, it appears that the small stoves without a heat exchanger but with a cozy will max out at around 18 minutes and 1/3oz of fuel. With a heat exchanger and cozy, and a slightly larger burner, this goes down to about 10min on the same 1/3oz of fuel. Efficiency is higher due to time being less, but raw fuel usage remains about the same.

Basically, I believe that heat transfer rates, get maxed at about 1/3oz for two cups. Or, around 10g/500ml of 50C water. From there there are fuel differences, pot size/material/thickness differences, windscreen/cone differences, ambient temp differences, radiative heat losses, laminar flow build ups (probably some I am not thinking of,) that are just as important as a heat exchanger. Heat not only flows into a pot, it will flow out of a pot, simultaneously. But, constructing these things is easy in a lab, but they are difficult to set up in the field. The "fiddle factor" increases along with each additional component…along with overall weight.

A mid-sized grease pot with a built in "fresnell" style heat exchanger to increase the bottom area by about 15-20%, and a tight fitting wind screen is what I use on most camping trips. Either with an alcohol stove or WG stove, depending on the length of the trip. Not the best, but, certainly not the worst. Easy to carry and set up. Easy to use.

@Heat not only flows into a pot, it will flow out of a pot, simultaneously.

It’s my belief that a pot of water surrounded by constant 300 degree flames is constantly absorbing water until it reaches boiling temps and then at that point it will start losing heat via steam out the top but yet continues to absorb heat through the walls of the pot.

DY
Adventures In DIY Stove Making

"Heat not only flows into a pot, it will flow out of a pot, simultaneously."

Heat generally flows from a point of high heat to a point of low heat. Why would it go both ways at once?

"It's my belief that a pot of water surrounded by constant 300 degree flames is constantly absorbing water until it reaches boiling temps and then at that point it will start losing heat via steam out the top but yet continues to absorb heat through the walls of the pot."

Where does the pot absorb water from? This doesn't make any sense.

–B.G.–

"@Heat not only flows into a pot, it will flow out of a pot, simultaneously.

It's my belief that a pot of water surrounded by constant 300 degree flames is constantly absorbing water until it reaches boiling temps and then at that point it will start losing heat via steam out the top but yet continues to absorb heat through the walls of the pot."

I think you meant heat in the above.

Anyway, energy is a two way street, If it radiats less than it absorbs, we say it heats up.

There was a light drizzle, 100% humidity when I did the tests outside the vestibule. One of the photos submitted shows the moisture on the outside of the pot being absorbed.

Not referring to Dans stove.

But just because a stove stays lit in a wind, doesnt mean a thing if all the heat is blowing away. It happens, even to cannister stoves that people think they dont need a windscreen for.

With a decent windscreen, wind isnt an issue. I often arrange my foodbag, water bottles, and other items around my stove to block any breezes. Really bad conditions, sleeping pad works fantastic, just dont get it too close.