Joel Hollingsworth wrote:
More benefit for less effort/expense might be to smear a touch of thermal grease onto the copper. This might also help prevent any galvanic corrosion of the steel.
i saw a tv program about ice makers that gave me a thought
if you flatten copper tubing a bit before you wrap it around a rocket stove you'd get more contact area
if you can weld, a die could be made out of 3 pieces of steel with a forth used as a punch, a hefty hammer and you're in business
Erica Wisner wrote:
ice doesn't explode. much.
steam does. dramatically.
Keeping copper pipe open, with no pinch points, helps avoid flash-steam problems.
That added surface area might replace 1 or 2 extra coils, but could cost you the entire coil (or personal injury etc) if it collapses the pipe enough to restrict flow.
Your die might let you create a consistent ellipse cross-section without collapsing the pipe. With great care, it might even hold that shape when the coil is bent into place.
This seems like a small performance tweak to a system that is still hobbling along like a 3-legged horse. I'd like to see more experimentation with the safe, effective places to put the pipe within the rocket system before trying to refine the pipe's surface area.
I think it might be possible to collect heat directly off the exhaust, by plumbing the pipe into the base of the barrel or nearby, in which case a round pipe would work just fine.
But maybe that's because I just spent $300 on copper pipe for Ernie to play with, and I sure don't want to create a kink in the middle by accident.
Hmm, this is all very interesting and you all make some great points. Thanks so much for sharing. What about running the black pipe up and down the length of the barrel or incorporate it to run the length of the exhaust pipe either on the outside up against it or plumb it on the inside of the exhaust pipe. Also having the hot side of the water on a rise will always give you a natural movement although it might be a bit slow. Interesting to hear your results.