[Stoves] Wick Burners: Martin's Tea Time Candle Stove

[AJH]

On Sun, 08 Oct 2006 20:49:53 -0700, rstanley wrote:

>Andrew et al, 

This suggests it was meant for the whole list so I have included
[stoves]

>If my old course on hydraulics is of any relevance "free" flow 
>(as in air, even as assisted by temperature differences/ stack effect) 
>through a tube of this sort would depend upon both the roughness coefficient 
>of the tube wall and of course on its diameter. I have found that in the 
>holey briquettes, for example that a diameter of the center hole which is 
>equal to but not exceeding 1/4th of its height ( briquette height ) is about 
>the optimal, assuming of course, a more or less equal roughness or the hole 
>wall. I beleive Tom Reid also documented as much with reference to hole 
>diameters versus height for flue gas velocity optimisation, some time back. 
>

This sounds reasonable and I have been told that a  tube needs to be 5
times its diameter in length to form a decent air jet.

>to wit;
>Your suggested use of rolled carton board, aside from the flame retardant 
>tendency of its glue, would only be ideal if the tubes were not to exceed 
>say 30 mm IN LENGTH. 

Well it seems to work at 150mm so the gaps between the rolls must
contribute, also the tlud stove works fine with woodchips where I
would expect the air gaps to contribute about 30% of the surface area.
>
>Otherwise you are relying upon air flow BETWEEN the rolls. It is also why 
>The multi holed "chinese briquette with its roughtly 12 mm dia holes in that 
>roughly 80 to 100 cm tall briquette form, seems to be far less than optimal. 
>Sure it  assure you a long slow burn but as many point out it is not burning 
>optimally and generating lots of ash in the process... 

Now ash content is another matter, interestingly I find that heavy
charcoal briquettes with a lot of clay binder cook more controllably
and longer, yet clearly you are paying for a lot of clay that ends up
as ash.

AJH