[Gasification] Carnot genset?

[Zietsman, Rex]

Dan wrote:
"On Fri, 2007-02-02 at 09:11 +0200, Zietsman, Rex wrote:
> I have a mechanical engineer (turbine specialist) friend who has been
telling me for years about his idea of building a Carnot cycle power
genset using truck supercharger components. I suspect that could work
here as well. He has also dreamed 

Do tell more, if you may... an actual _Carnot_ cycle?

> of building a 10kW gas turbine with one working part. I am bugging him
to do this as we can use gasifier gas to drive it. 

What do you mean by "one working part"?  (presumably something simpler
than a compressor and a turbine mounted on a shaft?)"

First of all, let's be clear here: the flows and sizes are small. The
Carnot cycle envisaged is as follows:
1. A compressor (suprercharger? turbo?) will compress ambient air.
2. The compressed air will be passed through a heat source - fire?
3. The hot gas will be passed through a turbo where it will generate
shaft power. This is where it gets tricky: The output shaft here has to
drive both the compressor and a generator. I will come back to that...
4. The depressurized hot air is used as combustion air for the fire with
the balance vented.

The challenge is getting the energy out of the hot air. It is logical to
use an integral turbo that will use the hot air to compress the ambient
air. How do we then get shaft power to drive the generator? It is this
expander that is interesting. If we can solve this step using available
off the shelf type components, we are in business. So far, we have
kicked the idea around and not really tried too hard to actually build
one. 

The turbine is an interesting one: you are right in that it is a single
shaft pushing out power and connected to its own compressor. By single
part, obviously there are bearings in this as well. In this case, we are
in the realm of turbine design and the unique challenges of that
technology. If only we could build a simple design that would easily
burn gasifier gas straight out of the gasifier... It would overcome the
tar issues, etc.

Rex