Pieces back in place after mortaring, and modded the air channel into two pieces:
Ready for fires!
Now the Rocket Stove is at a point where it works fine (does take a while to warm up…), as a space heater, which isn’t what I need, so If I want to get any use from it for heating, I need to run some ducting, which I drew up some plans for:
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.
Seems there are an endless supply of people using wood stoves to create water heaters, even a few who are generating steam for power generation. It’s so easy for me to complicate this with ideas use steam mechanical energy to pump hot water, I think first I want to understand how I can get efficient thermal transfer from the heat riser to a liquid, ie water heating. The most common way I’ve seen on youtube is heaps of copper tube, one guy used 150 feet just for steam!
Ok so this is an awesome rocket stove, just using a tree trunk section and some chainsaw work!
I’ve noticed the most common pipe diameter is around 3 inch around, and people seem to be getting heaps of heat with this. Mines way more than that, on the previous page, I showed a 3 inch diameter is 127cm sq thanks wolfram alpha! Whereas mine has a 190cm sq feed tube and 255 cm sq heat riser… So I guess if I can get this thing burning really well, it will burn through wood pretty dam quickly.