yes, I have been looking at alot of patent drawings and pics of gas travel paths, considering the sq. in. area of the exits out of the upper chamber of suspended pot base burners and the cross section of the passage ways.Sunny Boy wrote:You've got some leeway in that the flue gases can speed up and slow down as the cross sections of the areas it travels through change.
The other thing is, how fast do you want those flue gases going ? Obviously, the bigger the pathway the slower the gases travel giving time to shed heat. The reverse argument is that a large cross section pathway lets heat stay in the center of the pathway, away from the walls. Maybe more study of older stove's flue gas pathway proportions will give you a ratio like you found with your firepot's 27:1 ????
Paul
most of what i'm seeing is 6" final exit collars and 2 combustion chamber exits of about 4 x 4 into the drop path passages toward the base chamber. like on the Favorite #261. some others are harder to calculate because they are in a ring around the fire pot.
anyway the ratio seems to be between 15 and 30% more than the collar. in my case because i'll be using multiple openings it's going to be toward the upper end.
it wasn't really a mystery, I just think out load too much.