[Stoves] Small steam or putt putt steam

[AJH]

On Sat, 26 May 2007 20:03:45 -0500, Paul S. Anderson wrote:

>anyone have experience / knowledge / desire about
>generating about 50 psi of steam on a small scale?

Crest still has a page of pictures I did:

http://www.crest.org/discussiongroups/resources/stoves/AJHeggie/AJHAspirator.html


You'll see this was the simplest of experiments but I doubt I ever
exceeded 20psi.

In my first try the lance of the garden spray has a 10mm microbore
copper tube glued to it. The tube is coiled to sit in the flame and
there is a small propane nozzle screwed to a nipple soldered on the
tube. 

This set up had too big a water capacity in the coils so I later
changed to car brake pipe from a scrapyard.

I also added a water tap and if I did it again I'd add a simple one
way valve (perhaps the type used in the bottom of a car windscreen
washer bottle).

To reduce the water capacity of the coil I would also look at steel
diesel injector tube.

From my experiments I determined the steam adversely affected the fire
so I would also look at a simple tincanium fan. It seems possible to
have both the impulse turbine and the aspiration fan on the same rotor
but for tuning I think they should be co shafted and the aspiration
fan centrifugal type.

As I don't see how the thermodynamic efficiency of such a small set up
can get better than ~1% it's potentially very lossy, so enclosure and
insulation will be necessary if there is to be any benefit over the
cost of generating the steam.

You will need distilled or de ionised water and  an inline filter too.
I suspect if the nozzle got blocked and the copper overheated that a
rupture even at 20psi could scald seriously.

Overall I still favour a Thermo Electric device. Steve Taylor has
suggested that the number of junctions necessary with a metal-metal
device could be reduced because the lower voltage could be boosted by
a common DC-DC converter.

AJH