[Stoves] mesh wick finals

[Thomas Reed]

Dear Jigme and All:

Pure CO has a very low burning velocity and probably narrow flamability 
limits.  Contrary to popular opinion, charcoal freshly created  at 400C 
still has a significant (10 mole %?) hydrogen content and hydrogen makes 
all other fuels MUCH more combustible. 

Maybe the "old charcoal" had lost its volatiles.  Keep up the good 
work!  Love your"wick".

TOM REED       BEF

Jigme Rangdrol wrote:
>
> The original idea was to see if we could coax the gas from the 
> charcoal fuel to climb up a mesh frame and burn above the fuel bed 
> thus allowing us to see what was going on better and see subtle 
> changes in CO burns.
>
> The completed results of the mesh wicks is as follows.
>
> We did a total of six test burns. Each had a mesh wick made from 
> galvanized wire cloth. Each was a top lit fire with no measurement of 
> fuels. Each was performed in a coffee can with a wire mesh grate for a 
> bottom and the whole unit sat atop a stove pipe "T" to allow 
> unrestricted air flow from under the fuel bed to the burn zone.
>
> The first 2 forms were cylinders, one tall and one short. Neither the 
> blue flame thought to represent CO burns nor the flame "climbing" we 
> hoped for were evident. The mesh did not get red hot.
>
> The next form was a cylinder 1/2 the diameter of the first in an 
> attempt to increase the temperature. Still no blue flame however a 
> much improved burn. The mesh got red hot and it was clearly much more 
> uniform burn. The flames attempted to climb the mesh for as much as an 
> inch however they never really got higher than the fuel bed.
>
> The next was an outer cage to provide an air supply around the 
> charcoal as well as an inside mesh wick. There was never a blue flame 
> however we got red hot mesh with less fuel. It was clearly a colder 
> burn, less uniform and no real flame climbing was ever produced.
>
> The next was the same outer cage and a cone shaped mesh wick. No blue 
> flame but again red hot mesh and a better burn than the first outer cage.
>
> Finally the cone shaped mesh wick by itself. This got the mesh red hot 
> and burned very uniformly. Alas no blue flame however this shape was 
> an improvement as it produced the same results as the small cylinder 
> with a lot less fuel and has other usefulness.
>
> There were problems.
> The wind in the shop was a real factor for some of the burns and the 
> charcoal is old.
> Several "helpers" sometimes make the results more questionable.
>
> In conclusion.
> We found that the smaller diameter cylindrical mesh wick [ about 1/5th 
> the total diameter] provided enough air for a very hot burn. It got 
> the mesh red hot and the flame clearly sought and climbed the center 
> wick, presumably following the gas and heat.
> The larger diameters and outer cages seemed to cool the fuel down too 
> much for a red hot wire to be produced.
> Using the blue flame test for CO, there was either not enough air to 
> allow the CO to burn or it was not hot enough. We never got a blue 
> flame going in any of these configurations.
> The cone shape has definite appeal. It has an unfortunate but useful 
> burn pattern. It burns very hot at first as there is more fuel. As the 
> burn continues the "ring" of fire gets wider and less dense. This is 
> not so good for trying to get a wick going but very good for cooking! 
> It is a near perfect fuel load for a good boil and then simmer.
> The outer cage cooled the burn way down but it would be, as some of 
> the other forms no doubt, very useful at larger scales of fuel load.
>
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