In message ,
"IMM" wrote:


"Martin Angove" wrote in message
...
[...]

1: If suntrackers are so efficient, why is it that the only one at the
Centre for Alternative Technology is about 25 years old? Why haven't
they installed more? Is it perhaps that the reflectors are a waste of
time?

Lots have happened in 25 years. Do a Goggle on sun trackers. There are
some off the shelf versions from the USA.

The point I think I was making was that they tend to get the best/most
efficient stuff at CAT eventually, and will try (almost) anything in the
meantime. Unless something's happened since I was last there, the only
sun tracker is this 25 year old thing. If they were so good (in this
climate perhaps) then *surely* CAT would have installed a couple more
up to date versions? I can understand how they might fractionally
increase the efficiency of a system where direct sunlight is the norm,
but where diffuse light is the norm (i.e. here) where do you aim your
device? On top of that you've the extra mechanicals to maintain, and the
extra energy required to cause the thing to track.


2: Are you *sure* Stirling engines have high torque? The ones I've seen
certainly don't - they are very efficient, but only when operating high
speed/low torque.

Specifically steam engines have high torque at low speeds.

[snip the rest which interested parties have probably already read]

I understand that steam engines have high torque - but as far as I
understand it, a Stirling engine is *not* a steam engine, though I
suppose steam could be used as the heat source.

Unlike a steam engine, the cylinder is sealed.

Unlike a steam engine, the "working piston" isn't actually *in* the
cylinder, it is merely attached to it. In models it is often a sheet of
rubber, though I see no reason why a piston shouldn't be used.

Unlike a (modern) steam engine, the working fluid in the cylinder (air)
must be heated *and* cooled in order to complete one full cycle.

Can you post me some web references to the Stirling steam engine? I'm
very interested in the technology since coming across that boiler which
uses a Stirling engine on the exhaust to generate electricity. One thing
I don't quite understand about that thing though is whether it'd
actually get much use in a modern highly insulated house :-)

Hwyl!

M.

--
Martin Angove (it's Cornish for "Smith") - ARM/Digital SA110 RPC
See the Aber Valley -- http://www.tridwr.demon.co.uk/abervalley.html
.... Pop Tarts. Perhaps the most disgusting thing you can put in a toaster.