On Monday August 19 1996, Alec Cameron of (3:712/517.12) wrote to Chris 
Harper:
 AC> Ah, I learn geography at last. Other deserts have evening frosts!!
Even during summer?!?
 AC> If efficiency is of no interest and you want to make electricity, then 
you
 AC> will have to be very creative to figure a scheme that will score on
 AC> reliability, other than PV panels.
Efficiency isn't of NO interest, it's just a small concern for me. 
Reliability and total initial cost are of primary concerns. There is an 
abundance of solar energy both thermal and radiant, in the desert, so 
efficiencies can be less, hence my lack of concern about it. My primary 
system will be PVs. The secondary system will be via a solar furnace firing a 
boiler for steam. A flip of a mirror, and the furnace will be used for other 
purposes like pest control, (Dang varmits! ;-) melting metals or glass, and 
solar cooking. 8^p Maybe even heating the pool real quick! :-O
 AC>  In my head I am imagining a huge beam type engine
An iteresting concept. Something to play with. But I'm probly going to 
convert an old lawn-mower motor into a steam engine. Sounds a lot easier to 
me. Just change the cam's valve timing. There are many auto speed shops that 
do custom cam work here in the USA.
A high pressure heating coil fed by two high pressure water tanks with valves 
to shut them off during fill ups, and a rather large condensing coil made in 
several stages.
The first stage is made out of metal and a large diameter because of the high 
temp and volume of the steam. This will have many heat sinks soldered/brazed 
to it, both inside and out, to bring the temperature down rapidly, turning 
the steam into a vapor/steam mix, reducing volume and pressure. Maybe a lot 
of those steel drums you mentioned for your machine will do this.
The second stage will split into several smaller diameter high temp PVC pipes 
which will act as headers to distribute the water/vapor/steam to a series of 
many, many, large diameter water hoses or small diameter PVC buried 
underground so as to use the earth as a heat sink / thermal mass. This third 
stage will also hold the most water, which will be used for heating during 
those frosty nights.
A power take-off from the steam engine will pump the condensed water into one 
of the high pressure tanks, while the other is used to feed the boiler. 
Simple water level switches inside the tanks will control the electric 
valves, while measuring the generator's output will show the engine's RPM and 
will control the number of mirrors pointed at the boiler, for dynamic control 
of varying conditions.
As two high pressure tanks will be used to feed the boiler, one will be at 
low pressure for filling, while the other feeds the boiler, eliminating the 
need for expensive high pressure water pumps.
With a rather large condenser coil holding an equally large volume of water, 
the water itself will really be the thermal mass, reducing the need to bury 
the coil very deep under ground, and the costs of doing so.
The whole thing will be built in several stages. After the PV system is up 
and running to provide initial power, the solar furnace will be built. Once 
it's built, I can use it to melt metals for use in building the boiler and 
coils. I'll melt down lead from old batteries and add tin to make solder 
which will be used to coat the steel drums to prevent oxidation, and install 
the heat sinks. It will also be used to heat the soldering irons used in many 
stages of developement. The high pressure water tanks will have to be welded, 
so it won't help there. However, the furnace can be used to melt down old 
batteries to reclaim the metals, for sale or use.
RYL,
    Chris
--- GoldED 2.40+
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