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Experiments with an alcohol stove

August 13, 2023 — BarryK

Several days ago, I posted some thoughts about alcohol stove design:

So, considered testing with the combined Speedster burner and Packafeather adjustable stove. Also, I wondered how close the windshield could be to the pot and still draw the fumes upward ok.

So, I constructed an aluminium windshield tube, with brackets inside to hold a grill, on which the pot will sit. The gap between pot and innner-side of windhield is only 5mm (using my TOAKS 1000ml titanium pot). The aluminium sheet is 0.5mm thick. Photo shows the constructed windshield/pot-stand, alongside the Packafeather stove:


That grill is actually a fan grill. They have welded joins and will withstand considerable heat -- in fact, while testing it was glowing red hot and held together. I bought it from here, the "120mm" size, which is actually 115 wide by 115mm high:

With 500ml in the pot and the Packafeather vents wide open, it burned very hot. Here is a snapshot with the lights out:


From the post several days ago, I had the idea of combining the Packafeather with the Speedster, so set that up. Started with 500ml water -- a US cup is 238ml, so a bit more water than many tests on YouTube where they use two US cups for a boil test. No lid on the pot.

Winter here, cool evening. Didn't measure the temperature, but estimate ambient and water to be about 15 degrees C. With the Packafeather vent wide open, boiling was starting to happen after 10 minutes, became vigorous at 12 minutes.

At that point, I wound the Packafeather vents down to fully closed, and the flame became small. This is what we want for true cooking, to leave on simmer, so that the beans, seeds, legumes, or whatever, have fully cooked. Then waited until the flame went out...

The Speedster burner is "30ml" and at the start I put as much in until it was full. Didn't measure, but it would have been about 30ml. After a short time, turned the vent to be very slightly opened, then waited...

The flame went out after 48 minutes and 45 seconds!

Wow, that is a long simmer. That was yesterday. Today investigated the other idea from the post several days ago, of placing an aluminium doughnut-ring over the Packafeather stove. Also, instead of the grill, decided to use the Packafeather mesh stand:


Still using the Speedster burner, again filled to the brim. This time, it caught me by surprise. I looked at the pot after 8 minutes and 48 seconds, and hey, it was already boiling -- very vigorously. I don't know when it started boiling.

I immediately turned the Packafeather vent to closed. A couple of minutes later, the flame went out and I checked, all of the fuel was gone.

The lesson here is that the Speedster was getting too hot, boiling the alcohol too fast. Yes, got a very fast boil, but not so good for simmering.

Interesting, it is a balancing act. We don't want the burner, that is, whatever is holding the alcohol, to get too hot. Nor to cold -- which is why those who go camping in alpine areas carry some foil to put under the burner, as insulation from the ground.

This is all "fuel" for further thought. It would be nice to publish a DIY design that has adjustment like the Packafeather -- but doesn't require an actual Packafeather, given that they are no longer available.

And, I wonder if there is a tin can about that size. The aluminium tube that I constructed is 130mm outside diameter, 125mm high. Will go hunting the shelves at the local supermarkets.   

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