Thermo cyphon to drive barbeque spit?

[Steve Stone]

Hi everyone,

I was wondering if it might be possible to drive the spit on my barbeque using a thermo cyphon in a closed water system...

The idea being to have a standard 22mm domestic copper pipe running through the bbq fire. Both ends of the pipe would be connected to a small water tank away from the fire and filled with water and ice.

The bbq coals would heat the water in the pipe causing it to expand which would then cause the water to flow in a circular motion.

If I had a small paddle wheel in the water tank with the paddles directly infront of the inlet (the shortest pipe from the heat source) the flow might drive the wheel.

I have experimented with this idea, but the problem is power.

How can I increase the force of the water to drive the paddle wheel and so drive the bbq spit?

Many thanks,

Steve

 

[Danger]

Russ or Brewnog are probably best-suited to answer this. My thought is to restrict the outlet flow with a nozzle of some sort to increase the pressure, but I really don't know enough about it to be sure.

 

[Steve Stone]

Thanks,

I found this on the internet. Do you think it would work?

An array of several convection tubes are positioned in a series configuration to provide the equivalent of a very tall convection current generating tower, the pressure and fluid flow of the array thereby becoming capable of significant pressures such as the pressures necessary to move solar heated air into the confines of a rock storage area, the pressure increases of this array being achieved by the additive effects of connecting heated and cooled convecting columns together alternately in such a way that the output of one is connected to the input of another.

...Presumably, the cool tubes of water would be outside of the coals in the bbq - the water running in and out of the coals via the tubes.

What do you think?

Thanks for your help guys,

Steve