Originally Posted by colonel00
I think it might work. One thing to consider is how much will the heat source actually heat the bottom of the cylinder which could potentially keep the air towards the top stagnant. Give it a shot. If you were closer I would love to help.
I was thinking about this while I was working on a my "real" work. I could see whee the convective radiation could cause a rising column of heat that would interfere with the smoke moving freely to the exhaust. Perhaps a offset heat shield to keep the direct heat away from the bottom of the inner cylinder might be called for.
The physics of this work because as the fire creates the updraft in the space between the cylinders, the air pressure will increase at the top of the barrel. The pressure will automatically seek relief, which is accomplished by going down the inside barrel and out the unheated exhaust stack. Thermal transfer is always from hot to cold.