Volcano alcohol stove for small pots

[Tony Beasley]

The volcano stove is based on the principals that larger the stove flame/pot ratio the more efficient the stove/pot system is, (this is shown in my pot size/efficiency forum posting http://www.backpackinglight.com/cgi-bin/backpackinglight/xdpy/forum_thread/11467/index.html?skip_to_post=85986#85986)

And that slower heating is more efficient that fast boiling (fast boiling and efficiency with stoves is a myth that manufactures have perpetuated to sell stoves).

The cone top is to allow better air entrainment into the flame. The lip around the outside is for priming. The pin in the middle has the function of blocking the middle hole as well as transferring heat to the alcohol to aid vaporization and different size and mass pins can be used to adjust the flame strength. By this method I was able to tune the stove to improve its efficiency.

The stove is still in the development or tuning stage and has shown very promising results. I have had efficiency figures of 70%. The stove as pictured weighs in at 6 grams 0.21 oz). the pictured stove holds 25 mls the volcano can be made to hold larger alcohol volumes.

The volcano is made from the bases of two Red Bull cans with the top cone made by pressing between a specially made die. 8 x 1.3 mm hole are drilled in the top for jets and a 5 mm hole in the center for filling. The pin is machined from 6.35 mm aluninium bar. The bottom has been flattened out to allow for more volume.

The stove so far has only been tested on small diameter pots and has shown very good efficiency it also works very well with a JetBoil PCS pot that I modified. All of the small pot test have used less than 11.7g/80C (0.5 US fl oz/80C). I have not done large pot test yet but I expect some good results especially with the 1.5liter JetBoil GCS pot.

In the tests 0.5 liters of water was heated from between 20-25C to 95C and results extrapolated to get g/80C.

The best test result so far the volcano stove used 9.3 grams of denatured alcohol to heat 0.5 liters of water 80C and took 12 minutes. 9.3 grams = 11.77 mls = 0.4 US fluid ounces, in this test I used my modified 1liter JetBoil PCS pot. Of that 9.3 grams 0.55 grams (0.7mls) was used in priming.

Future developments will add a pot stand but this stove will work under most other pot stands.

Volcano stove

The flame

The flame pattern under a large pot

The flame under my modified JetBoil PCS pot

Some prototypes

[Brian James]

awesome!

I wonder if you could license the design to Trail Designs; maybe it's the ultimate Caldera burner?

I'd almost be willing to ship my Caldera to you in Aus if you shipped it back with a Volcano stove when you were finished! :)

I wonder how much shipping from my house to yours is…

[Steve M]

Tony, great write up. I have not tested this but have an idea to further increase fuel efficiency for small flame type alcohol stoves.

After heating the bottom of the pot the remaining hot gases flow up the sides and transfer some additional heat to the pot. Some of this heat is lost to the sides of the windscreen or Caldera cone. This would be particularly so when the barrier is made of aluminum, exposed to wind and has vents below the top of the pot (Caldera cone). And as we know, heat loss increases significantly when wind speed increases.

Suggestion: Thin titanium foil could be used as the wind screen and a circular sleeve of fireproof cloth (CarbonX or Nomex for example) surrounding it. This would reduce the cooling of the slowly rising hot gases from your volcano stove and thus allow more heat transfer to the pot. I'd make the windscreen & a CarbonX "cozy" about 1-2" higher than the top of the kettle. The wind screen "cozy" could also serve double duty as a dinner bag/freezer bag cozy.

Might be a fun test to try (?) should you have some time to kill…
Steve

[Tony Beasley]

Hi Steve,

Thanks for your suggestions, I will look into them, what has to be thought about is if the weight gain in making the windscreen longer and heavier is worth it.

I have measured the hot gasses going up the side and from the JB pot it is not that hot about 30C and the with the small billy pot it is about 45C this means that the hot gasses flowing up the sides will actually pull heat away from the sides when the water reaches above those temperatures. I think the JB cosy would probably be more effective.

Tony

[Joshua Mitchell]

So, super-slow burn then? That looks like not much more than a candle flame…nice.

[Rog Tallbloke]

>slower heating is more efficient that fast boiling (fast boiling and efficiency with stoves is a myth that manufactures have perpetuated to sell stoves).

Hi Tony, great looking stove and superb figures. As you know, I've been playing with stove and kettle design and have now got some new test figures to share. You can help me with the maths if you like but I think it's around 60% efficient :o) My stove also weighs 6g including the primer cup and the kettle is 2oz without insulation, which weighs another 1/4oz.

425ml water at 10C to boiling at 99.6C
9.4g (12ml) methhylated spirit plus 0.5ml for priming. ( roughly 95% ethyl alcohol 5% methyl alcohol)

Now here's the reason for quoting your comment about boiling times, my kettle has the boil time down to 5mins 45secs for the 15 UK floz (around 14.4 US fluid ounces. Fast boiling isn't everything, but it's nice to get that cuppa sooner rather than later on a windy cold day. ;-)

Gives the pot less time to lose heat to the atmosphere and a stronger stove flame is less affected by cross winds in adverse field conditions too. I guess there are different optimum compromises to be made depending on the type of country you like travelling through and the seasonal weather you encounter.

[Tony Beasley]

Hi Rog,

“As you know, I've been playing with stove and kettle design and have now got some new test figures to share. You can help me with the maths if you like but I think it's around 60% efficient :o) My stove also weighs 6g including the primer cup and the kettle is 2oz without insulation, which weighs another 1/4oz.

425ml water at 10C to boiling at 99.6C
9.4g (12ml) methhylated spirit plus 0.5ml for priming. ( roughly 95% ethyl alcohol 5% methyl alcohol)”

With your figures I calculated 61.8% thermal efficiency and for the efficiency ratio that I use I calculated 9.85g/80ºC/0.5l, not to bad at all. A 2 oz (57 gram) pot or kettle is very light, I look forward to finding out a bit more about your design but I suspect greater surface area of the kettle design and slowing down the hot gas flow helps with efficiency and boil times.

You are right about it is nice to get a cuppa sooner rather than later, when my walking partner came back from the US with his JetBoil I could not believe how fast it was for a cuppa, in testing I have had times of 2m 30s to boil using only a little more than 4 grams of fuel. My tests are done in my garage with no wind and I try and do them with an ambient of around 20ºC to give consistency, there is nothing like testing a stove in the field especially in windy cold condition, a few if my earlier remote canister stoves have failed in the field, I always took a backup.



”Now here's the reason for quoting your comment about boiling times, my kettle has the boil time down to 5mins 45secs for the 15 UK floz (around 14.4 US fluid ounces. Fast boiling isn't everything, but it's nice to get that cuppa sooner rather than later on a windy cold day. ;-)

Gives the pot less time to lose heat to the atmosphere and a stronger stove flame is less affected by cross winds in adverse field conditions too. I guess there are different optimum compromises to be made depending on the type of country you like travelling through and the seasonal weather you encounter.”

You have brought up a very good point about fast boiling times and I do not fully understand what goes on with efficiency and boiling times but I will go back to some earlier testing that I have done, this might help explain my statement about time and efficiency. Below is a graph that I have previously posted the results of boiling 1 liter of water from 20ºC to boiling 98.5ºC using a Trangia (Alcohol) red line, MSR Whisperlite (White gas) blue line and a MSR pocket Rocket (canister gas) yellow line, in all tests the flame was set to as fast as the stove could go then graduated to the slowest (or smallest) I could set it. In these tests I used a 1l Snow Peak Ti pot.

I will start with the Pocket Rocket (Yellow line) I was trying to find the optimum valve setting for fuel used vs time and in the graph it is clearly shown that with boiling 1 l of water boiling faster than 12 minutes uses more fuel and the faster the boiling the more fuel used, but after 12 minutes this there is no improvement in fuel used, I have repeated this test many times with 1l and 0.5l (which produced a time of 6 minutes for the optimum boil time vs fuel usage) and it was always the same results. On this information I base my statement “slower heating is more efficient that fast boiling (fast boiling and efficiency with stoves is a myth that manufactures have perpetuated to sell stoves)” for it is mainly the canister gas stove manufactures that use fast boiling times as a claim of high efficiency.

With the Trangia (red line) I was able to slow the flame down by the simmering ring that comes with the Trangia. The Trangia did not use more fuel the no matter how much longer it took to boil the 1l (this is the same for 0.5l). I do not know if it has any significance but please note that the fastest boil time for the Trangia of 12 minutes seemed to be the same as the optimum boil time for the Pocket Rocket. I have not tried these tests with a faster heating alcohol stove as I do not have one that can heat faster. The times of 6 minutes to boil 0.5l fits in nicely with your 5m 45s to boil 0.425l.

I have only started testing my Volcano stove, but on one of the faster test that I did, it took 8 minutes and used 10.7g/80ºC, slightly more than other tests, I have not done enough tests on the volcano to see what is the optimum efficiency time, I will do some more testing on the weekend.

With the Wisperlite (blue line) it is a very inefficient stove and blasts most of its heat out the sides of the pot when the flame was slowed down the efficiency improved and I suspect that a point could be reached that the efficiency would not improve with time, this stove was very hard to adjust.

I hope this helps

Tony

[Rog Tallbloke]

Hi Tony,
thanks for the accurate maths conversion, and again, great work with the graphing! Just to clarify for others, in your last paragraph you said the wisperlite was the yellow line but as you stated earlier, it's the blue line. I have an MSR stove I run on good old cheap unleaded petrol, white gas is pricey over here in the uk, and usually sells under the coleman brand. Coleman stoves do not like unleaded forecourt petrol and it's one of the reasons I've never owned one.

The way to get an MSR to a low simmer is to let pressure out of the fuel bottle by partially unscrewing the pump unit, but be careful to aim the bottle neck away from the stove when you do this, and never in an enclosed space: those vapours are flammable!!

Trangias are great in the field due to the comprehensive (and heavy) base unit which steadies the airflow to the burner. I'm employong a similar principle in my latest design.

As you note, pocket rocket style canister stoves are just a quick method of consuming lots of fuel unless you trim them to a minimum burn and shield them well. Trouble is, in very cold weather, they don't vapourize fuel well at low settings unless you wrap a piece of copper wire over the burner and round the gas canister to transfer heat….

[Hikin’ Jim]

Tony,

Thanks for your recent link to this post.

I'm curious; have you done further work on your Volcano stove? It looks quite promising. The problem I have with many alcohol stoves is that the flames wastefully lap up around the sides when I use a Heineken can or the like. Your stove would be perfect for a small base diameter pot.

A note about the MSR Whisperlite: The original version (pre shaker jet) of the stove simmers far better than the modern version (shaker jet). When MSR changed over to the shaker jet, they changed the geometry of the pre-heat loop, raising it higher above the flame. Perhaps raising the height of the pre-heat loop is helpful at high flame, but it is no good at all when trying to similar. Sometimes an old Whisperlite can be had for "cheap as chips". Might be worth looking into if you like fiddling with stoves, although hardly an ultralight alternative. The jet on the pre-shaker jet Whisperlites looks like the top portion of a golf tee. The modern Whisperlite jet looks more like a conventional brass nipple and of course has the weighted shaker needle in it.

HJ

[Tony Beasley]

Hi Jim,

>I'm curious; have you done further work on your Volcano stove? It looks quite promising. The problem I have with many alcohol stoves is that the flames wastefully lap up around the sides when I use a Heineken can or the like. Your stove would be perfect for a small base diameter pot.

Thanks for your interest. Shortly after posting about my Volcano stove design I did some more design work to make the design more attractive with a view to maybe selling some but I was not happy with the new design and went back to designing and making canister stoves, I might do somemore development on the volcano stove soon.

>A note about the MSR Whisperlite: The original version (pre shaker jet) of the stove simmers far better than the modern version (shaker jet). When MSR changed over to the shaker jet, they changed the geometry of the pre-heat loop, raising it higher above the flame. Perhaps raising the height of the pre-heat loop is helpful at high flame, but it is no good at all when trying to similar. Sometimes an old Whisperlite can be had for "cheap as chips". Might be worth looking into if you like fiddling with stoves, although hardly an ultralight alternative. The jet on the pre-shaker jet Whisperlites looks like the top portion of a golf tee. The modern Whisperlite jet looks more like a conventional brass nipple and of course has the weighted shaker needle in it.

I have one of the old pre-shaker Whisperlites but in winter prefer to use my Coleman Extreme, in summer I use a60g Kovea Supalite.

I started designing and making a UL white gas stove but was talked into making a UL canister stove, I have plans to re-visit the the idea of making a white gas stove one day but for now it will have to wait.

Tony

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