I assume that you have done the heat transfer calculation properly.

You can calculate the resistance of your pipe as R = \rho*l/A. You can calculate the current requirements based on power P = I^2*R. You can calculate the voltage based on Ohm's law V = i*R.

So, do you have a big enough power supply to do what you need?

Or are you asking something else?

The calculations indicate a need for at least 1.5k amps current to generate the required heating considering the losses. I just need to know if anyone else has done work in this range ..or if it is actually feasible to go on with this plan. I am looking for someone who can share some experimental experience in this area.

I return to my original question. Do you know that you can get a power supply big enough to handle the current and voltage requirements that you have calculated? Aside from asking whether anyone else has done this kind of set up, you absolutely need to look (on line for example) to see if you can find a power supply to handle your requirements.

As for heating hollow tubes with current flow, I have done this on a smaller scale in the past. High currents (up to about 10 amps) were required, and I found a power supply for what I needed. I had gas flowing through my tube. With water flowing through your tube, you will probably also have to consider how best to insulate your system electrically.

Yes the setup I have can handle around 2k amps, 20V at best. So in any case if this design is used I will have to make sure that I can use the existing power supply. Buying a new power unit will cause delays.

If I use a small dia tube say 1 inch, and low thickness(1-2 mm) and length(300-500mm), the power requirements will down significantly.

The electrical insulation question is something I need to look into. But if you have some ideas regarding the insulation problem, please share.

Thank you sir for you varluable comments.

Could you please explain the configuration of your system better. Perhaps you can draw a picture and post it. I still do not understand whether you have liquid (water) both inside and outside the tube, why the tube cannot be heated from the outside with conventional heaters, whether the steam is to be generated inside or outside the tube, and why the tube is only _partially_ filled with water.

Another question to ask is, how will you electrify the tube? With that amount of power you may get some arcing and burn the tube, which happened in a local lab accident with a 600 W heating tape. As Dr. Weimer noted, a schematic would help everyone greatly to understand how this system works.

Finally, what pressure are you planning to operate at?

Two questions you need to answer first, are: (a) how much heat can you generate electrically? (that's electrostatics); (b) what is the maximum temperature you can achieve? (that's a heat transfer problem). Then you will know how much steam you can produce.

The main idea is to concentrate a liquid which will be passed through the rotating tube (inside the tube). The equipment is basically a thin film evaporator. The film is formed on the inside wall of the pipe due to the pipes rotation.

The equipment is essentially a simple hollow tube in horizontal orientation, rotating about its axis, connected to the power unit using a pair of slip rings. The idea is to heat the tube electrically and not use conventional heaters in order to use a thermal camera to capture the outer wall surface temperature profile. If a conventional heater is used, pipe surface will not be accessible and options will be limited to use of lots of thermocouples in order to generate enough data points. The operating pressure is general atmospheric pressure.

As per general calculations including losses, the heating requirement is at least 5kw. With the power unit available and a small enough experimental set up, this heat requirement can be satisfied. I would expect the outer wall of the pipe reaching temperatures in the range of 250-300 deg C, with inner wall temperature reaching above 100 deg C in order to boil off the liquid water fast.

But now that Mr.Michael Nolan indicated the possibility of arcing, I am not too sure of how to avoid such a situation.