A buddy and I have been tinkering with DIY (Do It Yourself) alcohol stoves on and off for the last couple of years.



I thought I'd put together a blog post on the design principles that I have learned as a result of all the tinkering and testing. What follows is NOT a "follow the steps and you'll get such and such a stove." Rather, I list some basic design considerations for making decent DIY alcohol stoves. For pragmatic reasons, the post is limited in scope to open type burners made from aluminum beverage cans.

For those of you who would like to try your hand at making such stoves, at the end is a list of "standards" that you can benchmark your DIY stoves against.

So, without further ado, I give you: DIY Alcohol Stoves -- Basic Design Considerations

HJ

Interesting, I've only tried penny stove so efficiency of alcohol stove never occured to me. Where would rank a penny stove (following the exact dimension on the author's website with 355ml soda can) in efficiency and effectiveness?

I haven't played with the penny stove. If you want to see if it's efficient, take a look at Standards For DIY Alcohol Stoves down at the bottom of my blog post. Just run your stove a few times, see how much alcohol it uses, and then compare your usage with that listed in the Standards.

Just as a general FYI, there are basically five types of alcohol stoves.
1) A plain open burner such as an "Altoid" burner, with or without fiberglass insulation (or pearlite or similar).
2) A ducted port or "chimney" stove like a Brasslite, 12-10, or FeatherFire.
3) A semi-presurized stove, which is the type in my blog post. These are also called "open jet" type stoves.
4) A pressurized stove with fully enclosed fuel. A penny stove is of this type. These are also called "closed jet" type stoves.
5) A wicked stove where some type of wicking material is used.

HJ

Nice little stove.

Thanks.

HJ

I tried it outside at -5C, after 3 attempts and freeze my butt off I gave up, not going to happen. 15 ml of ethanol is just not enough, water would get warm and have small bubbles at bottom of pan but nowhere near boil. If I throw more fuel at it I have no doubt it'll boil, but with the fuel consumption rate I might as well use a manufactured stove.

Well, perhaps I'm off my rocker, but I just don't see it when it comes to using alcohol as a stove fuel in temps below 0C. Alcohol doesn't have a lot of heat per gram compared to canister gas or liquid petroleum based fuels. When it's cold, higher heat output is desirable in order to get cold, cold water up to the boiling point.

If you take a look at my Standards for DIY Alcohol Stoves, my suggestion is that 15ml should be able to boil 500ml of water that is 20C. I'm guessing that if the air temp is -5C that the water temp was less than 20C.

My attitude is save the alcohol stove for temps above at least 5C and preferably 10C. Use petroleum based fuels in colder temps. Just my perspective.

HJ

I know, I just like to mess around with it. Last winter I tried to light a fire with firesteel and wood shavings made on the spot in -20. :p

I did discover something useful though, at this temperature lighting alcohol with firesteel requires a whole different technique than warm weather. One need to drop a burning glob of metal directly into alcohol to ignite it, spark shower won't do. This means if alcohol is used for preheat for liquid stove, a light/match is absolutely necessary since due to location of the preheating pads dropping a glob onto it is next to impossible. Haven't tried coleman fuel yet so don't know if firesteel is going to work with that.

Don't worry about igniting Coleman fuel (AKA white gas). It is the most volatile fuel out there....

Did some really basic tests this afternoon with somewhat surprising results. I used my typical alcohol stove based on Don Johnston's Photon Stove. The windscreen stand is constructed of lightweight sheet metal with holes punched for ventilation. The pot stand is a simple bent clothes hanger wire.

Parameters:
Interior, no wind, air temp 23*C, 1.3 litre GSI Boiler, (3 cups) 0.71 litres VERY cold water, homemade pressurized jet alchohol stove, 25ml fuel in stove, 5ml fuel in preheating cup, average of 3 tests for each fuel, altitude 585m. I turned on all my kitchen fans and cracked a window open to ventilate since I was inside for these tests.
Measured time to when fine bubbles begin to form on the clear lid.
Measured time to when steam appears to get past the lid.
Measured time to rolling boil.
Measured time to burn fuel.

Methanol 99.9% (meythl hydrate) Energy density by wt = 20.16 MJ/kg
Bubbles: 4.92 minutes
Steam: n/a
Boil: n/a
Burn: 8.61 minutes

Denatured ethanol 95%/5% Energy density by wt = 26.8 MJ/kg
Bubbles: 6.38 minutes
Steam: 11.00 minutes
Boil: 11.94 minutes
Burn: 13.19 minutes

Observations:
Ethanol took longer for the preheat cup to vapourize the fuel to enable the jets of the stove to work.
The fuel also did not burn as quickly/energetically from the jets hence the burn time was longer and actually brought the water to boil unlike the methanol.
Ethanol burned with a bluer and less visible flame; the methanol had some yellow tones.
Ethanol exhibited a definite sweet odour while burning.
I was really disappointed the methanol didn't achieve boil (it did get it hot enough for tea!) In real life, I must be using more fuel in the stove and the preheat cup since I only measure by look when I am out in the field. I mormally get a boil and a very energetic jet flame.
Note: after checking it appears ethanol has a lower vapour pressure than methanol which MAY explain why it doesn't make use of the pressurized jets as well.

I then used the shallower, slightly wider 0.8 litre pot that came with the set. I couldn't quite get the ful 3 cups of water in it. The lid doesn't fit tightly so the water steamed and escaped and it took slightly longer to come to a rolling boil, which is why I never use this pot in real life.

Just for comparison, I got out my Coleman Xtreme with Powermax fuel.
Bubbles: 2.50 minutes
Steam: 4.50 minutes
Boil: 4.75 minutes
Burn: n/a

Even though the Xtreme stove is fairly heavy, it is dependable and is unbeatable when it comes to boiling water, esp. in cold weather. It can also do a decent simmer. Too bad the fuel cannisters are no longer available. I have about 9-10 left and if I can find somebody with any stock, I'd buy them out.

You might wonder why do I use 3 cups of water when most others test a pint or 2 cups? Simple -- that's about what I use in real life. I need enough water for my 12oz insulated plastic cup to make tea! The rest of the water is used for my meal.

________________________
I discovered a tiny hole in the bottom centre of the stove I was testing. A couple of drops of fuel leaked out during the process. I will need to repair that with a bit of heat resistant epoxy.