An open source stove project in progress.
Here we see the Peacham Volcano , closely modeled on the Swiss Volcano stove, as it is used. The cup, from a Swiss Volcano stove unit, with the water to be boiled sits inside the iCan made from a single pineapple juice can. The iCan, in turn, sits on two angle irons inside a three pound Costco coffee can. This outer can has four functions: 1] wind shield; 2] insulation and heat retention; 3] modulates the air flow into the system as the size and number of holes varies; 4] safety — as the bottom is intact, it catches any stray hot coals.
With an ambient temperature of about 6.5 degrees C and water of about the same temperature, on a windy and blustery New England Fall day, the Peacham Vulcano was able to boil 400 ml of water in just under 10 minutes. On a fuel load of about 3/4 cup of wood pellets, this translates to about 150 ml of fuel per liter boiled. This was done with a minimum of smoke and soot.
Wolrdstove reports that their small, patented, Lucia stove, not a TLUD, only requires about 80 ml of wood pellet fuel to boil one liter of water at 10 degrees C ambient temperature with 10 degree C water. This raises the interesting question of what is the limit on the efficiency of natural draft TLUDs with no moving parts?
On the other hand, the open source Peacham Volcano stove, excepting the cup with tapered sides, costs $0.00. This may make the Peacham Volcano a natural companion to the Lucia stove when it comes to both education and entry level use. In both these cases, cost is a significant factor in the rate of diffusion and adoption of cooking with the heat of pyrolysis.
This shows the core of the Peacham Volcano stove. Note that the “pot” sits in the exhaust stream and is thus heated around all sides and the bottom. This configuration also exposed the least amount of the pot to the chilling effects of cold winds. This reminds me of old wood cook stoves that had removable rings at some burners to allow pots to sit directly in the hot flue gases. What is old is new again. This suggests that not only does the heat engine have to optimized, but that it may be very beneficial to consider the pot as a part of the system that must also be optimized. Clearly the goal is to create a result greater than the sum of its parts.
The Peacham Volcano stove with the pot from a Swiss Volcano stove. Here you can see that the pot has tapered sides such that it does not block the exit path of the hot exhaust gases.
Note: The Swiss Volvano stove is based on full combustion of the fuel. It’s desired final product is only mineral ash. The Peacham Volcano is based on pyrolysis of the fuel. It’s desired final product is elemental carbon biochar. When evaluating stoves, it is important to also take into consideration the utility and value of the final product: ash vs biochar.
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