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James Byrnes
(backfeets1) - M

Locale: Midwest.... Missouri
alcohol stove wind screen on 04/18/2012 03:20:10 MDT Print View

Has any explanation been proposed as to why an air barrier, in the base of a wind screen, speeds up boil times? I found this info on youtube.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: alcohol stove wind screen on 04/18/2012 04:05:36 MDT Print View

What is an air barrier?
Sounds typical YouTube to me.

Cheers

Michael Ray
(topshot) - MLife

Locale: Midwest
Re: air barrier for alcohol stove wind screen on 04/18/2012 08:47:24 MDT Print View

I had to wonder the same thing, Roger.

Air Barrier video. I'd not seen this mentioned here before but from Jon Fong's posts here that I've read, he knows a lot about alcohol stoves and their design. I see he runs Flat Cat Gear.

Jon Fong
(jonfong) - F - M

Locale: FLAT CAT GEAR
Air Barrier on 04/18/2012 09:32:57 MDT Print View

The air barrier started out as an experiment to see if I could make a cone windscreen less sensitive to the wind. A horizontal barrier plate was added to separate the upper, flame area of a stove with the lower reservoir section of the stove (http://youtu.be/AxX6EOTNG7I). What I think I found were two effects: one that the barrier focuses the inlet air to help shape the flame of the stove. As the plate got closer to the outlet of the flame, the more the inlet air “pinched” the flame creating a tighter flame spot. Secondly, the “burner volume” was reduced thereby increasing the temperature around the top of the stove (causing a faster burn rate). Those were my thoughts anyway - Jon

BTW - this is the original air barrier video (http://youtu.be/EU_jKlJ9r1Y)

Edited by jonfong on 04/18/2012 09:35:57 MDT.

Ultra Magnus
(Ultra_Magnus) - F
Re: Air Barrier on 04/18/2012 11:09:47 MDT Print View

I like this explanation- "Here's what's happening, the plate directs a small amount of incoming air to the flame where it gets used in the fire. Key is it keeps loads of cold air from flooding in & cooling the pot."

It's esp. true if your windscreen has lots of airflow, so you get convection drawing in more cold air than is required for combustion, which would cool the hot gasses as they rise up the sides of the pot. I've had the thought to try something like this out, but never did for 3 reasons, lazy, lack of free time, and it looks like it would be awkward to pack, but that could be overcome. Mostly for the first two reasons... I did do something like that for my wood-gas stove though, which I've only bench tested...

BM