On Jan 26, 3:54 am, nos...@[EMAIL PROTECTED]
(Paul Ciszek) wrote:
> In article <Itmmj.458$5K1...@[EMAIL PROTECTED]
>,
>
> Fred Klingener <gigabitbuc...@[EMAIL PROTECTED]
> wrote:
> >"Frank Scrooby" <X...@[EMAIL PROTECTED]
> wrote in
messagenews:fnchp1$1j1$1@[EMAIL PROTECTED]
> >> Greets
>
> >> Spotted these links:
> >>http://www.popularmechanics.com/science/earth/4243793.html
>
> >>http://www.johnsonems.com/jhtec.html
>
> >> Wonder what the residents here would think?
>
> >Sign me up. The fundamentals are there. I hate and end up not paying
any
> >attention to SF (or listen to political campaign promises) that
violate(s)
> >the first or second laws of thermodynamics. JTEC doesn't, so that
attribute
> >alone sets it apart.
>
> I quote from the article:
>
> "says he can achieve a conversion efficiency rate that tops 60 percent
> with a new solid-state heat engine."
>
> Using the aforementioned 2nd law of thermo, the maximum possible
efficiency
> of a heat engine is:
>
> Th -Tc
> Eff = ------
> Th
>
> If Tc is "room temperature", or 293K, then Th has to be at least 732K or
> 459C (or 859F). In order for his "solid state heat engine" to work over
> that temperature difference, whatever magic material it is made of has
to
> retain its magic properties at the high-end temperatures. Color me
very,
> very skeptical.
>
> >This is especially true in cases where the heat input is "free" - e.g.
solar
> >or waste heat from a central station power plant (or, as with Watt,
you're
>
> If you are trying to extract energy from the waste heat of a power
plant,
> you are getting in the way of the power plant's attempt to dump that
heat.
> Better to improve the efficiency of the big-ass heat engine that is
> dumping the heat (and will work better the lower its "cold side"
temperature
> is) than to put a second heat engine between it's exhaust and the
ambient
> temperature.
I'm guessing that what is _meant_, rather than what was putatively
_said_ was that of all the energy theoretically available, this device
can recover 60%. So if you're talking about, say, 500 K and 300 K,
you're talking about 60% of 40% or 24% overall efficiency. In the
context of the advertised claims, this sounds reasonable.
Science exposition is hard wrok.
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