Scott Dufour wrote:

Arne Kverneland wrote: Fans don't seem to do the job. They just make a disturbing wind. 

I'm replacing "Fans" with "_______", and making this my new mantra for anything I see on the political news channels.

Very apposite: we are just coming up for an election here!

 

This afternoon I made another try. I shaped a length of 10mm (od.) copper tube to a ring (resembling a question mark) and drilled a number of 1mm holes for air jets in it to sit around one of the Origo stove’s burner. I first connected it to only one outlet of the aquarium pump (from now on called the booster). It definitely improves combustion, but there is not enough oomph in it to turn the flame fully blue. I then fed both outlets to that copper tube, and even drilled more holes in it. I am unsure of this. It could be that the pressure is on the low side or that the air capacity is insufficient. After all, the booster's combined capacity of 360 litre/hour is only 100ccm per second.

Anyway, before I again hook up the car tyre pump, I will try to fix the tube to the stove and then find if time to boil 0.5litre of water is shorter with the booster on than with it off.

Here is from today’s test, without and with the booster on.

Arne

20170918 The Origo burner without the booster (air pump) connected

20170918 seconds later: The booster is adding air to the flame via about 15 1mm air jets. Note the copper tube surrounding the burner.

(see photo album section 5)

Annie Hill wrote:

You can, of course, get little fans that run from dry cell batteries, but I doubt that they would suit.  I'm watching with interest.

Fans don't seem to do the job. They just make a disturbing wind. The air jets from that initial test with a copper tube looked more promising. Now I have received the aquarium air-pump which hopefully will produce the necessary pressure. A good thing if this turns out to work, is that the setup doesn't require one to raise the pots higher on the stove. It can be used just like before.

I hope to make a little test today.

Arne

I should have known, a person has to get up pretty early in the morning to beat you to an idea Arne!  I look forward to hearing how the rest of your experiment goes.  

I had similar ideas Arne and was inspired by some of the small DIY alcohol backpacking stoves that can be found readily with a youtube search.  Some work on similar principles to the Origo, while others use jets to create a vortex.  The models that are successful in creating a vortex seem to burn intensely with a clean blue flame.  I tried modifiying my Origo to add curved radial fins (imagine a squirrel fan) which would encourage the incoming air to form a vortex and thus mix more efficiently with the vaporized alcohol.  I was never successful, but I currently have way more projects than time and I only attempted trials for a couple of evenings before I abandoned the project for a Maxi stove.  If you could figure out a way to form a vortex with the incoming air, you might have a solution that didn't need to rely on electricity.  Here is one example using a Trangia stove, which has some similarity to the Origo.