# Heating water

## Main Question or Discussion Point

I need to find the most efficient way to each 600 ml of water without using an electric heat source or any non human power. I thought i would use a combination of agitation and cavitation, with a screw with lots of "dimples" that create the pockets of low resistance that would create cavitation inside a tube. I can't find any information on cavitation other than what it is on a basic level so i have a few questions.
1) is this even worth it? is the heat caused by cavitation going to be significant enough in such a short time?
2) if it is, how can i maximize it? Should i use a narrower tube with a longer screw to spread the water out? or should i have a thicker tube so i can maximize the surface area of the screw blades, maximizing cavitation?

though i'm in high school, i've studied into multivariable calculus so if you have any equations whatsoever, please share them no matter how mathematically complex. any help would be greatly appreciated.

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Get on a stationary bike with an alternator/dynamo, and put a resistor in the water. Get an eggbeater with a crank, and modify it to increase turbulence. Put the water in a cannister, pump the pressure in the cannister up to a high pressure, then let it out through a very fine seive (like a porous plug). Get a hand-crank transfer pump and do the same thing by recycling through pump.

The stationary bike should generate 100 watts (~1/8th HP) for 30 minutes.

Bob S

I want to create my own idea. that's where the fun is. I'm looking for helpful information about cavitation principles and water heating in general, not a pre-made design to follow, though I appreciate the effort.

russ_watters
Mentor
The main thing to consider is conservation of energy. The details of how drag is generated are less important than the torque and rpm themselves.

1) is this even worth it? is the heat caused by cavitation going to be significant enough in such a short time?
no.

2) if it is, how can i maximize it?
high RPM is necessary to maximize cavitation....but it's a useless exercise...

Try reading here for possible ideas...
http://en.wikipedia.org/wiki/Heat