BOIL TIME COMPARISONS:
As stated above, the whole purpose of this project was to make a lightweight home-made alcohol burning stove similar in size and shape to a Trangia alcohol stove. Since I did not have access to a Trangia stove for this testing, I sent a final version of the above stove to a friend of mine, Todd Schlender, for the boil time comparisons between the home-made stove and a Trangia. The below data is a compilation of his testing.
Apparatus:
POT: Mini-Trangia 28 pot (without lid, blackened bottom)
POT STAND: Mini-Trangia 28 pot stand
WATER: 16 oz room temperature tap water
FUEL: Methanol -- enough to fill each stove
STOVES: Mini-Trangia 28 (3 oz weight); Home-Made stove (1 oz weight)
Experimental Procedure:
16 oz of room temperature water was measured out into the Mini-Trangia 28 pot. The pot was left uncovered to monitor the boiling of the water during the test. The stove was then filled with methanol and then placed inside the pot stand. the stove was lit and the uncovered pot filled with water was placed on top of the stove stand. The amount of time required for the water to come to a rolling boil was then monitored and recorded.
The following was the order that the stoves were tested in:
First Stove Test: Tested home-made stove; once water boiled, noted boil time and then extinguished the flame. Then waited until the stove was cool enough to touch and removed it from the pot stand.
Second Stove Test: Same as the First Stove Test (above) except with the Mini-Trangia 28.
Third Stove Test: Retested home-made stove; waited until the water boiled and noted time, removed the pot (leaving burner going) and then refilled the pot with cool water, placed the new pot of room temperature water on the burner, and brought the water to a boil a second time and noted this boil time.
Fourth Stove Test: Same as Third Stove Test (above) except with the Mini-Trangia 28.
NOTE: Boil times are assumed to be less when a covered pot is used.
Results and Discussion:
The First and Second Stove Tests were a direct comparison of the stoves running cold -- as if the stoves were just removed from the pack and used for the first time out. The Third and Fourth Stove Tests were a comparison of how the stoves would react if more than one pot of water was heated during the meal with the stove left burning in between boilings.
In the direct comparison testing (First and Second Stove Tests) it was found that both of the stoves brought the water to a rolling boil in 10.5 minutes. So, in this instance the stoves were identical if a person was just boiling one pot of food or drink.
In the multiple boiling pots testing (Third and Fourth Stove Tests), it was found that the stoves acted differently. In both cases, the home-made stove brought both pots of water to a rolling boil in 10.5 minutes each. The Mini-Trangia 28, however, brought the first pot to a rolling boil in 10.5 minutes and the second pot to a rolling boil in 6.5 minutes.
These results were very interesting to us. Why would the home-made stove take longer to boil the second pot of water than the Mini-Trangia 28? Also, why would the Mini-Trangia 28 boil the second pot of water faster than the first? In doing a Web search to answer these questions, we happened upon a post that showed similar results with a Trangia when the burner was left running boiling one pot of water right after the other:
http://saffron.hack.net/lists/arch/at/9703/msg00911.html
Unfortunately, no theory was put forth to answer this question. The only theory that we could come up with was that as Todd put it: "[In theory] the hotter the stove burns, the faster the alcohol boils, which increases the pressure which jets the gas out faster which makes it burn hotter which brings us back to the beginning. So maybe if the Trangia gets a little bit hotter, which causes it to boil a little bit faster, which lets it get a little bit hotter, etc. etc. and it just takes the Trangia longer to get up to speed…" At this point, though, no further investigation has been done to prove or disprove this theory. It may be as simple as adding some sort of lightweight, flameproof, insulating layer to the outside of the home-made stove to keep the heat from dissipating from the home-made stove as quickly which would allow the alcohol to boil faster. Further work will have to be done in this area.
Conclusions:
As can be seen from the above data, the home-made stove compared well with the purchased Mini-Trangia 28 in the direct boil time comparison testing. Both stoves boiled the same amount of water in the same amount of time. The multiple boiling pots testing was where the differences were seen with the Mini-Trangia 28 boiling the second pot of water faster than the home-made stove.
When a stove is used in camp, it is cold on the first time using it so using the home-made stove is a very good alternative to the Mini-Trangia 28 if only one pot of water is going to be boiled at that particular meal. If multiple pots of water are to be boiled, the Mini-Trangia 28 will save a person a couple of minutes of boil time on the second pot of water boiled which would turn into a savings in fuel.
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