11 Sep 2014
Thinking about a new steel rocket stove heat exchanger design today, this is what I’ve come up with:
Water travels up the copper tube(s), pretty self explanatory, red arrows are the hot air. 12mm copper cost around $5 per m, so not ridiculously expensive… Ideally the air gap between the tubes at the top would total say 110% of the heat riser cross sectional area, so it can flow just a little easier through the heat exchanger with maximum contact. Also dont want to cool the heat riser too much, nor stop the flow of gasses by forcing the air down (as opposed to it falling down due to being heavy after burning) Hmm…
I modified the location of the fire box to be closer to the heat riser. Which wasn’t super keen to play along when I tried to get a fire going.
Now that I cut a vertical feed tube, I may have been better off with just horizontal, as the vertical feeder didnt want to stay alight.. Maybe just needs better adjustments.
I think I’m ready to bin the cement design. The heat riser is too wide, people are getting really good results with all metal smaller designs. Although if I can get the fire box to work, I could possibly have success running an metal air duct in a spiral through the drum as a hot air blower, then run that duct through a window… 125mmx3.6m ducting cost $24 (for outside the drum to house) so… not impossible.