Hi Russell,
When you talk of a regenerator on the Stirling Engine, what kind of
thing are you talking about? What materials do you use?
Best regards
		Luis



-----Original Message-----
From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf
Of Russell McMahon
Sent: 26 August 2006 00:13
To: Microcontroller discussion list - Public.
Subject: Re: [OT]:Sandia, Stirling to build solar dish engine power
plant

> Russell, et all, will now argue the point.


No arguments.
I'll just point out  a few 'facts' and be on my way to the church AGM 
:-)

> Notice the date. It didn't happen. Again, stirlings are not 
> reliable.

That, of course, very much depends.
Their siameses twin, Stirling cycle coolers can be and are made as 
reliable as all get out. When your are being designed to live in a 
ComSat you have t be.

> They are either A) inefficient and long lasting or B) efficient and 
> wear out
> quickly. ...

You seem to be, surprisingly, so I may still be asleep, which is 
entirly possible, confusing efficiency with power density. Properly 
designed and built built Stirling engines, ie not the numerous model 
ones whose designers have no idea about the absolute need for a decent 
regenerator for real purposes, are as about as efficint as anything 
around. What they are generally not, and what you may mean, is that 
they are not "power dense". ie they tend to be large in volume and 
possibly in mass for their power output. There are reasons for this, 
which is no excuse when comparing them against alternatives. But in an 
"alternative energy" world and for non-nobile applications this is 
often no big deal. Lifetime is an increasing issue as you attempt to 
improve volumetric power density.

> They don't even have a C) option with high cost and both efficiency
> and long life as far as I can tell. And yet people keep throwing 
> money into
> them. I'm sorry, but at what point is that stupid?

Something / one is stupid if you don't like its face. There are 
several good reasons to keep trying. But I'll not expand at length 
now, except to say that

> How much money do we need
> to waste on something that has been around for just about forever 
> and has
> NEVER been cost effective?

*WHEN* the big boys (or the little girls) finally crack the problems 
it will rule the world (tm) and replace many alternative systems 
BECAUSE the external heating feature allows any heat sourcem use of 
low grade and "waste" heat, better efificency in any give case than 
any alternative and ... . The mighty Philips organisation threw in the 
towel - but that was due to accountants and other issues. They 
estimated it would cost (AFAIR) 60 BILLION dollars to get it truly 
right. And that the payback period would be under 6 months once 
someone did.

At that point nothing is stupid :-)

ie once you achieve this holy grail it will be the biggest cash cow 
ever known.

Which is not why the little guys do it. They have other motivations. 
Many are at least as sensible ones as James' drive to ride electric 
bike/car thingies, grow chickens, use solar panels etc.
An interesting data point. NZ mborn and made Whispergen whose ad I 
posted recently are THE most succesful Stirling maker ever (depending 
on your metric) and in the process of gearing up to fill orders for 
AFAIR 100,000 or so Stirling engines. Why doesn't that count? (special 
circumstances notwithstanding)




        Russell. 

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