Re: Solar-hydrogen home power system?

From: Thomas Lee Elifritz (lifeform1_at_atlantic.net)
Date: 11/09/04 

Date: 9 Nov 2004 07:02:09 -0800

November 9, 2004

gherbert@retro.com (George William Herbert) wrote in message :

> >George William Herbert wrote:

> >> The compressability of water is an insignificant third order effect
> >> in their work. At the bottom of the Challenger Deep, the density
> >> is about 3% higher than at the surface.

> >Which is far from insignificant.
>
> It leads to a roughly 1.5% difference in pressure at that depth.

Which is far from insignificant
 
> Most submarines dive to less than a km.

But the interesting ones go far deeper.

> Research subs and ROVs
> that can go down several km are less common but a legitimate design issue.

Then I rest my case.
 
> Given that the design margins for sub pressure vessels are typically
> on the order of 1.75 to 2.0, a 1.5% pressure difference is insignificant.

Wrong.
 
> I have not personally designed subs or ROVs which were built.
> However, I have talked shop with those designers and have done
> paper and viewgraph engineering on subs. I can assure you that
> professionals consider it insignificant.

Which is why almost all the really good design software nowadays have
built in water compressibility toggles. It's simple to code and it
gives you more accurate numbers.
 
> Regarding dams, I challenge you to work out the numbers for the
> compression of the water at the bottom of the world's tallest
> extant dam.

It's vibration and resonance under stress that worry me.

<snip vanity>
 
> Resonance modes of what, and decompression modes of what?

Decompression of fluid filled sealed containers.
 
> The structural response of a sub's pressure hull and its
> compression and expansion are a legitimate field of study.

Especially when the bolts start popping. Zing, watch out.

<snip more vanity>

I've put up with a lot of curious *** from you George, but your
insistance that water compressibility is insignificant and may be
safely ignored in all cases and in all aspects, in the modern day
world of scientific and technological exploration and large and global
engineering projects, which we now find ourselves living in, on, under
and above, takes the cake. These are science newsgroups, and I have
scientific as well as engineering standards and very little patience
with fools anymore. You are in my filter file.

Thomas Lee Elifritz
http://elifritz.members.atlantic.net

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