Vince Morgan wrote:
> "Don Kelly" <dhky@[EMAIL PROTECTED]
> wrote in message
> news:fxF8k.51809$gc5.48712@[EMAIL PROTECTED]
>> ----------------------------
>> "Vince Morgan" <vinharAtHereoptusnet.com.au> wrote in message
>> news:4863074c$0$30464$afc38c87@[EMAIL PROTECTED]
>>> In a previous post I raised the question of whether or not excess
>>> electrical
>>> energy could be obtained via a sparkgap.
>>> The consensus, based on published research was a resounding 'no'.
>>> However, whilst ferreting about I came across what appears to be
>>> 'considerable' material from highly respected institutions that claims
>>> otherwise.
>>> E.g..
>>>
>>> "Liberation of chemical energy in pulsed high current arcs in liquids
> and
>>> gases
>>> Graneau, N.
>>> Dept. of Eng. Sci., Oxford Univ.
>>>
>>> This paper appears in: Pulsed Power 2000 (Digest No. 2000/053), IEE
>>> Symposium
>>> Publication Date: 2000
>>> On page(s): 19/1-19/4
>>> Meeting Date: 05/03/2000 - 05/04/2000
>>> Location: London, UK
>>> References Cited: 7
>>> INSPEC Accession Number: 6623248
>>> Date Published in Issue: 2002-08-06 23:27:03.0
>>> "
>>> [quote]
>>> Abstract
>>> High current pulsed arcs in both water and air, are able to liberate
>>> chemical energy from the arc medium which can be recovered in either
>>> mechanical or electrical form. Despite the high currents, the arc is
>>> relatively cold which apparently makes this a highly efficient
mechanism
>>> for
>>> liberating stored chemical energy and therefore a possible future
energy
>>> source. In the case of water, hydrogen bonds are broken in order to
> create
>>> the observed small fog droplets. The energetics of small droplet
bonding
>>> requires that the remaining hydrogen bonds will be expected to drop
into
>>> lower energy configurations than in bulk water and thus the transition
> to
>>> droplets can release a large amount of chemically stored energy.
> Similarly
>>> in air, arcs break covalent bonds which are also a source of stored
>>> chemical
>>> energy. It appears that more mechanical energy is liberated in the
water
>>> arcs for a particular discharge energy. However the lower mass and
>>> consequent higher velocities of the end products of the air arc
> explosion
>>> probably explain why the these arcs are more suited to direct
conversion
>>> to
>>> electrical energy
>>> [/quote]
>>>
>>> I've taken particular note of "the transition to droplets can release
a
>>> large amount of chemically stored energy"
>>> This is of course energy that can be accounted for. So too that
> released
>>> in
>>> air via broken valence bonds.
>>> I also took note of the required "kiloampere current" which is sort
of
>>> outside the definition of "sparkgap" I guess.
>>>
>>> Comments?
>>> Vince
>> --------------
>> I do not read this as implying that the energy liberated exceeds the
> input
>> energy.
>>
>> What I read is that there is, in the configuration used, there is a
>> particular input energy that is optimal - higher efficiency than at
> higher
>> or lower input levels. That is reasonable.
>> --
> Perhaps I am reading this incorrectly. As I am the only one who thinks
> otherwise, and due to my inexperience, you are probably correct.
> But, but, but. What does the following mean in that context.
>
> [quote]
> However the lower mass and consequent higher velocities of the end
products
> of the air arc (As opposed to water: me)explosion probably explain why
the
> these arcs are more suited to direct conversion to electrical energy
> [/unquote]
>
> And what could this mean?
>
> [quote]
> highly efficient mechanism for
> liberating stored chemical energy and therefore a possible future energy
> source.
> [/quote]
>
> Why would one consider energy conversion if what you have is less than
it
> cost you in the first place?
> I'm probably wrong, because I usually am ;)
> Regards,
> Vince
>
>
>
Hi Vince,
You read correctly. A similar paper, "Arc-liberated chemical energy
exceeds electrical input energy" can also be found in the Journal of
Plasma Physics (UK) (2000), 63: 115-128, by Dr. Peter Graneau. Other
papers dealing with underwater electrical explosions include:
"Electrodynamic explosions in liquids", Applied Physics Letters, March
1, 1985, Volume 46, Issue 5, pp. 468-470, by Peter Graneau and P. Neal
Graneau
"Powerful water-plasma explosions", Physics Letters A, Volume 117, Issue
2, 28 July 1986, Pages 101-105, by Roy Azevedo, Peter Graneau, Charles
Millet, Neal Graneau
"The Anomalous Strength of Cold Fog Explosions Caused by Water Arcs",
Pulsed Power '98 (Digest No. 1998/258 and 1998/441), IEE Symposium on
1-2 Apr 1998 Page(s):40/1 - 40/3, by Neal Graneau
In the first cited paper above, Dr. Graneau used a capacitor bank with
known initial energy to create an underwater arc within a volume of
water inside a thick steel tube. The explosive capacitor discharge
creates a fog that exits the tube at high velocity (100 - 1000 m/s)
depending on the initial bank energy. Graneau measured the momentum and
energy of the high velocity water fog using a ballistic pendulum. He
found that, for many (but not all) "shots", the kinetic energy of the
water jet exceeded the initial energy of the capacitor bank by as much
as 40%. Additional energy was (apparently) liberated from the media, but
the mechanisms have not been identified. The phenomenon was relatively
repeatable...
Bert
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