[Stoves] Trials on TLUD Gas Burners - Counter Current Flow

[Boll, Martin Dr.]

Hi Julien,

Since years I am curious about counter-current-flow. I saw it in a commercial wood-saw-dust-stove. Which is quite different to TLUDs, but worth to look and think about.

- Have a look to DEOM-stove (made in Belgium and France). I told about it in the stoves discussion an Nov. 2005. But the old link does not work. 
Meanwhile there is en English version of the website as well. Take now: 
 http://www.deomturbo.com/page.asp?DocID=65472&langue=EN  (picture shows it's intestine)

There is a similar stove available in Great Britain:
 http://www.workshopstoves.co.uk/greenheart-workshop-stoves.asp ( only outside-view)

My personal remark to the DEOM: 
1. The blow-tube reaches quite long into the burning-chamber ; by that, secondary air (here it is more or less in the same time primary air) is given near the fuel-bed, so that 
2. the flames have a lot of path to burn. 
3. By nearly  strait upside-down flow within the blow-tube there is no retardation by a curved-flow. The cold(er) air falls into the hot burning-gasses.
4. The length of the tube is longer than 5 times the diameter; that I was told, is the condition to form a non-turbulent stream; I think the condition for the air-stream to be more "penetrating/invading" into the gasses; and to reach the fuel-bed.
5. Mind:  the blow-tube has a massive mantel of iron. -That is to prevent deforming, because the tube gets very hot during the stove-operation; -There is as well a cast-iron-lining of the walls.

Difference to other "normal" convenient  stoves:
It can burn saw-dust and wood-chunks
It can be easily relight to flame from some few-glowing charcoal-rest. ( In normal use, the blow-tube is closed or partly-closed for continuous burn, -otherwise the stove would get too hot)


Thoughts on your experiments:
- I propose to think of blowing secondary-air against the glowing charcoal as analogue to the kerosene-jet  against a baffle-plate by a kerosene-burner. 
-In one case is the jet of fuel into air, 
-in the other case the jet of air into the fuel. 
Both must be mixed and it burns best (or only??) by right ratio. In both cases there is a big range of different fuel-air-ratios, and even important- different gas-speeds; somewhere is (nearly) always the right speed and mixing ratio for burning, that means the range (must be ) between flash-back and out-blow, -which, I think is narrow by woodgas; and must be hit to fit.

- Did you already think of blocking partly the secondary-air-rim, to get sharper air-jets . The idea is inspired  by normal butan-gas-burners, by the Belonio-gasifier and by the spherical gas-burners with numerous small flames, which can be modulated ( e.g. Viessmann Vitodens 300).


Thanks for your clear and informative "flyer"  -You presented tin-can-burners very attractive.
Keep on counter-curent-flow!

Regards
Martin