Diagonal Slot Stove

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WanderingStovie
Posts: 122
Joined: Thu Jan 23, 2014 4:20 pm

Diagonal Slot Stove

Postby WanderingStovie » Mon Jan 19, 2015 9:46 pm

I am designing and testing a side burning alcohol stove with eight diagonal slots centered 1" down from the top rim. The top rim of the stove supports the pot. The stove is 2" tall and 2 1/2" in diameter. The bottom of the slots is 3/4" from the bottom of the stove, and the top of the slots is 3/4" from the top of the stove. Each slot stretches across 1/8 of the circumference. The stove should hold 30 ml / 1 fluid ounce of fuel when resting on a level surface.

Tonight I added 20 ml of denatured alcohol to the stove, lit it, waited 20 seconds, and set a pot with 2 cups of 68F water on the top rim. The water reached a final temperature of 177F with all 20 ml of fuel burned. Flames rose up the side of the pot, and at times burned outside the exhaust holes at the top of the windscreen. The next test will be with 25 ml of denatured alcohol.

I rate the efficiency as poor, at least with a small diameter pot (Halulite Minimalist). The one bit of good news is it stayed lit until all the fuel burned, after a warm up period of only 20 seconds.

The stove is constructed from a steel can (4 ounce Del Monte fruit), the bottom 48 mm of a 7.5 fluid ounce aluminum soda can (Sprite), and two strips of aluminum taken from the side of a larger aluminum beverage can. One strip is 9/16" tall and joined with tabs to form a capillary hoop with a circumference 1 mm smaller than the inside of the fruit can. The other strip is 1 1/2" tall and joined with tabs to form a capillary hoop with a circumference 1 mm larger than the soda can. A 2" diameter hole is made by filing the bottom of the soda can. Four semicircular notches are punched around the edge of the 2" hole with a 1/4" paper punch.

When the fuel at the bottom of the stove is ignited, heat passes through the soda can to vaporize fuel drawn up by the 1 1/2" capillary hoop. A ring of flame appears at the top of the burner. The flame spreads to the eight slots, where it warms the fruit can. Heat travels down to vaporize fuel drawn up by the 9/16" capillary hoop. After setting the pot on the burner, the soda can and inner capillary hoop block wind from passing through the stove, but contribute little to fuel vaporization, since they are no longer in contact with the flame.

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zelph
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Joined: Tue Aug 14, 2007 1:53 pm

Re: Diagonal Slot Stove

Postby zelph » Thu Jan 22, 2015 12:31 am

Why the interest in the swirl of the flames? Capillary hoop design, what's up with that, why so popular, needs a pot support and seems to be inefficient, burns hot???
"Nothing Ventured Nothing Gained" stove store = http://www.woodgaz-stove.com/

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WanderingStovie
Posts: 122
Joined: Thu Jan 23, 2014 4:20 pm

Re: Diagonal Slot Stove

Postby WanderingStovie » Mon Feb 16, 2015 11:20 pm

This design was just another crazy idea I tried. It has capillary hoops, but does not produce a swirling flame. At the other end of the spectrum, a penny stove does not have a capillary hoop, but I built and tested one with jets that converge to form a swirling flame.

There are numerous designs that use the capillary action of wicks or hoops. A burner can reach its maximum fuel vaporization rate much sooner after lighting if it uses capillary action, which reduces time to boil. I think that is the main reason for the popularity of capillary action.

Your Starlyte uses wicking material to hold fuel in suspension, which is great for safety. Without the built in stand, it is also convenient for carrying fuel. But from what I have read, the Starlyte heats water faster when used with extra fuel. I prefer to avoid that effect. I choose to use capillary hoops in my designs to minimize the amount of suspended fuel. For safety, I want a short burner with a wide base, and a separate pot stand.

Some people burn methanol, and want to store the burner in the pot, but worry about fuel contaminating the pot and/or whatever else is stored in the pot. They want to extinguish the burner, pour any remaining fuel back into the bottle, and burn off whatever fuel did not go back into the bottle. They will choose whichever design minimizes the amount of fuel that has to be burned off because it could not be returned to the bottle. Among designs with capillary action, a burner with a grooved/creased capillary hoop seems to be the best choice for them.

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WanderingStovie
Posts: 122
Joined: Thu Jan 23, 2014 4:20 pm

Re: Diagonal Slot Stove

Postby WanderingStovie » Tue Feb 17, 2015 12:13 pm

zelph wrote:Why the interest in the swirl of the flames? Capillary hoop design, what's up with that, why so popular, needs a pot support and seems to be inefficient, burns hot???


With a wide pot and a good conical windscreen, a capillary hoop stove can boil 2 cups of 70F water with less than 15 ml of methanol (Heet in the yellow bottle) in less than 4 minutes. I refer you to the work of BirdBrain, who has far more experience optimizing the capillary hoop design.

http://www.appalachiantrailcafe.net/index.php/Thread/230-Alcohol-Stoves/?postID=24058#post24058

The link may not take you to the exact post, so scroll down to BirdBrain's third post on Apr. 6th 2014 at 3:20 pm.



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