I was a circuit designer, starting with tubes, then transistors and then
programmable gate arrays. Didn't break into gates until long after I
wanted to.
As a teen, was dabbling in relay logic, telescope design, astronomy,
geology, theology, fossils...
Now am into peak oil. Greatly recommend The Archdruid's Report.
Ol' Bab (old Babcock - I coined this in my 40s, now look at me)
PS Am glad you got to see my post: I haven't seen it yet. Maybe only
you has seen it.
On 4/10/2014 4:16 PM, Bob Cook wrote:
Ol"Bab--
What kind of engineer were you?
Older Bob?
----- Original Message -----
*From:* David L Babcock <mailto:olb...@gmail.com>
*To:* vortex-l@eskimo.com <mailto:vortex-l@eskimo.com>
*Sent:* Thursday, April 10, 2014 1:55 PM
*Subject:* Re: [Vo]:Problem with glare at Ivanpah CSP plant
It is a little more complex. There is a distance from the
(presumed flat) mirror such that the angular extent of the mirror
is about the same as that of the sun (1/2 deg). From there out the
intercepted flux decreases, by the square of the distance.
From the birds view, at that distance it sees the whole sun fill
the mirror. Any farther out the image is bigger than the mirror
-only part of the sun is supplying heat.
If the mirrors are curved, then each mirror will have a hot focal
point, but not super hot: again it is limited by the angular
extent of the sun and the mirror. A ideal mirror will project an
image of the sun on the boiler (or bird, if at focus), and the
intensity is that of sunlight multiplied by the square of the
ratio of the two angular extents. Maybe 10 or 20 to 1? WAG here.
As Bob points out, the "nimbus" effect strongly suggests that the
designers were aware of a possible problem and made sure mirrors
in standby don't all point at a single point, or even parallel.
Ol' Bab, who was an engineer.
