----- Original Message -----
From: Frederick Sparber
Why is this interesting?
http://www-methods.ch.cam.ac.uk/meth/ms/theory/esi.html.
"The production of ions by evaporation of charged droplets
obtained through spraying or bubbling, has been known about for
centuries, but it was only fairly recently discovered that these
ions may hold more than one charge. "
Well, Fred, this may not be what you had in mind, but for one
thing, it points to another (slightly different) direct conversion
method.
At least eight cycles have been used and studied for converting
heat - thermal energy into electricity. Three of these, the
Rankine, Brayton and Stirling cycles, are well-known and involve
dynamic conversion. where a pressure differential pushes against a
structure to impart torque, and are not "direct" conversion but
involve complicated systems, dedicated heat rejection, and Carnot
limitations.
While the others : thermoelectric, thermionic, and
magnetohydrodynamic, and Alkali-Metal Thermoelectric Converter
(AMTEC) are static systems which may or may not be fully Carnot
limited, can generally use passive heat rejection, and are far
less comlicated. Obviously thermoelectric - if it were efficient
would be "the ticket" for alternative energy needs - but despite
the grandiose claims of some which still linger on the internet,
when one looks a little deeper - there is "no beef" to
high-efficiency TEC... yet.
The un-named eighth method is somehwhat lesser known. So much so,
that I cannot even remember the name, and a quick google search
turns up nothing - but it is a version of AMTEC/thermionic in
which an alkalai liquid is actually "boiled" to carry away
negative charge but does not require the Beta-alumina solid
electrolyte membrane of AMTEC (or the similar sodium-beta-alumina
battery of FMC). If memory serves, the sodium boiler was
inverstigated by Ford motor and others in the eighties as an
offshoot of the battery. But since that time I don't know what has
happened to it. Corrosion was a problem - as is always the case
with alkalis at high temperature. Since the vapor pressure of Na
is low, lots of heat is needed - but there could be a work-around
hybrid converter, using Fred's pneumatic nebulaztion technique -
but with He or H2 instead of air as the vapor medium.
But your post brought to mind a way that a particular nebulizer
approach could accomplish something similar but at significantly
lower temperatures. To actually "boil" away electrons in
significant quanities usually requires temperatures over 2000 F -
a huge problem with sodium metal and is one reason that I
suggested earlier that your "heat pipe" idea would not fly - for
use at lower temperature to replace thermoelectric conversion. It
is just difficult to get ions at low temperatue - yet the
nebulizer (and the steam-electric predecessors seems to do that.)
ERGO if one could devise a two part system with both Na and He
such that the Helium was nebulized in the Na, and could then carry
away something like 10^6 more ions at a given moderate
temperature- based on vapor pressure (lets say we are shooting for
the 800 F at the high end of the exhaust manifold in automotive
transportation) - then yes that could possibly work.
Sodium istelf can carry away lots of heat even at its low vapor
pressure, but not many ions - comparatively. The combination,
however, could be synergetic depending on how this nebulizer
dynamic functions - what do you think?
Jones
