John Ferrell <johnferrell <at> earthlink.net> writes:

> No offense taken regarding the still. It turns me off because anything I 
> have fermented or distilled has fallen far below the quality of cheap wine!

Where I come from they say if it's strong enough the taste does not count
because you can't feel it anyway ...
 
> You sound very well organized and have done your homework well but you would 
> not be the first to underestimate the power of steam.

Thanks, I am not so well organized. I do not underestimate the power of steam,
but imho most people thing of a steam engine along the lines of 'let's boil 
some water and then ...'. Some reading up on how power stations work is in 
order to dispel this myth. The steam used to sterilise surgical ustensils, 
make coffe and peel skin off dead animals is not in the same category with 
power station steam.

> Heating the whole supply of water is inefficient and dangerous. A separate 
> boiler may add a little complexity but will likely be worth the effort.

I agree, the best way is a 'tube' heater with counterflow (using light that is
not so straightforward but anyway ...). The problem with this is the same as
coffee machine vs. power station: it has to use very pure water and advanced
controls or there will be no tubes left after a few days at most. The 'kettle'
style Victorian technology is much more forgiving.
 
> If you choose to use the pressure cooker as a steam source consider:
>     Limit the volume of water in a test cycle to a small amount.
>     Fabricate or buy some kind of pop-off regulator that you can adjust to 
> your needs to further assure a safe operation.

I would like to use an unmodified kettle as is for testing, using the original
regulator output as open vent to the nozzle of the turbine. This means that the
vessel will never be closed. The original burst disk will be in place. Also I
will use a thermometer.
 
> I consider steam power a sleeping giant that will become a more important as 
> the cost of petroleum continues to rise. The Stanley Steamer automobile was 
> never refined but the technology is still there.

I am not sure. Oil will certainly run out but Carnot's physics will not change
and steam is a really bad idea efficiency-wise unless high tech is used to
handle it. Consider that all the high efficiency motors built to date did 
*not* use *any* phase change (as in boiling). The reason is obvious: the phase
change 'hides' a huge amount of energy from the thermodynamic cycle. While
boiling water energy is put into water that does no work. When it condenses
energy travels out of the water and does no work. You don't want any of that
unproductive transformation in an efficient cycle. At the very last it makes 
for huge and heavy plants for steam (as they all are). 

I think that it is more likely that high tech materials will allow high 
pressure closed cycle thermodynamic engines to work more reliably. That means
H2, He, even CO2 at very high pressure in a closed circuit not unlike todays
refrigerators (but without phase change for power output - as opposed to with
phase change for cooling/heating where the phase change's heat transport
properties are desirable).

F.ex. few people realise that a normal refrigeration circuit can be used to
extract energy if the compressor is reversible (it is not for most built units
unfortunately). Such a device could run from the temperature difference between
air and water in a lake, both in summer and in winter, for example.

It would be nice to see such units mass produced so they can be used in solar
and waste heat applications.
 
> BTW, model airplane builders sometimes use plastic soda bottles for pressure 
> accumulators to operate retractable gear. They burst about 150 psi. Of 
> course they will not take the heat of steam. There has to be something in 
> the trash pile that will.... Maybe an empty butane container? Don't forget a 
> safety pop-off!

I know but I think that the unmodified pressure cooker is a 'tried' thing. It
can supply the steam for a tiny engine or turbine so some figures can be
obtained. So far there are too many question marks about this system. 
Everything is 'estimated' so far. I do not like that. 

Meanwhile I found another source for a boyler: There are small coffee machines
that are meant to be put on a stove. They do not work at 15 psi but they also
have the burst disk etc as in a pressure cooker.

Peter


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