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The Ghost In The Machine
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 Posted: Sun Aug 24, 2003 1:00 am Post subject: Re: 298K Superconductivity where are you? |
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In sci.physics, w_tom
<w_tom1@hotmail.com>
wrote
on Thu, 21 Aug 2003 19:39:54 -0400
<3F45584A.F60FF41B@hotmail.com>:
[quote]What is the freezing point of methane?
[/quote]
-183 Celsius, at standard atmospheric pressure.
[quote]Can it be taken low
enough and still remain gaseous or sufficiently liquid to pump
under sufficient pressure - a thermodynamics question?
[/quote]
Pressure sufficient for what? That question>s already answered
routinely; "natural gas" is mostly methane.
If you>re referring to keeping a superconductor cool,
then -183 C = 90 K. This is barely cool enough
to cause a ytterbium-barium-copper-oxide mixture
to superconduct (92K). It might be adequate for a
thallium-barium-copper-oxide mixture, which requires 125K.
There are some issues here regarding freezup of the
methane, similar to water icing of pipes in winter,
although probably not quite as destructive, since I
doubt methane expands upon freezing. Nor do I know the
particulars regarding the Meissner effect, and thereby
how much current a superconductor can pass while still
superconducting, relative to current copper wiring.
I do not know the stability of these compounds when
exposed to air; pure thallium and ytterbium do not remain
pure for long in the presence of air or water, at normal
temperatures. Of course, for superconductors that may
not be much of an issue, as they>re too cold to react. :-)
Methane boils at -164 C, which means any equipment operating
with liquid methane may have to contend with wildly differing
pressures in an emergency. Admittedly, this isn>t much
of a problem -- a flare pipe does the job in a pinch.
[quote]
The Ghost In The Machine wrote:
...
An interesting notion, but absent more data, methane is
a better fuel per cubic meter. The carbon-hydrogen
bond has more energy than hydrogen-hydrogen, and there
are more of them.
There>s also the issue of heating the cooled hydrogen, in
order to burn it.
...
[/quote]
--
#191, ewill3@earthlink.net
It>s still legal to go .sigless. |
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William David Thweatt
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| Posted: Tue Aug 26, 2003 2:16 pm Post subject: Re: 298K Superconductivity where are you? |
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Richard Saam (rdsaam@att.net) wrote:
: Dave
: I did a Chemical Engineering News search on this. Faster than looking
: through my stack of magazines. The reference is as follows:
: *****************
: NEWS OF THE WEEK
: BUSINESS
: October 8 , 2001
: Volume 79, Number 41
: CENEAR 79 41 p. 11
: ISSN 0009-2347
: Nanotube Firm Building Pilot Plant
: ANN THAYER
: Carbon Nanotechnologies Inc. (CNI) has signed an engineering services
: contract with engineering firm Kellogg Brown & Root (KBR) , part of
: Halliburton , to build a pilot plant for producing single-walled carbon
: nanotubes. Houston-based CNI was founded early last year by Rice
: University professor and Nobel Laureate Richard E. Smalley , former
: Lyondell Petrochemical CEO Bob Gower, and others from Rice University to
: commercialize carbon nanotubes.
: MOVING UP Smalley, in front of a carbon nanotube laboratory reactor
: brought from Rice, speaks at "groundbreaking" for CNI>s new pilot plant .
: The pilot plant, to be completed by the end of this year at KBR>s
: Houston technology center, will produce 200 to 300 g per day. Process
: improvements to upgrade production efficiency are expected to increase
: that to about 1 kg per day by mid-2002.
: CNI intends to be much more than a manufacturer of exotic materials,
: anticipating that it will participate in carbon nanotube product and
: market development. "The game is now afoot," Smalley says. "We think we
: can turn this into something real."
: CNI will use production from the new plant in collaborative development
: projects. Electronic uses, such as flat-panel displays or
: electromagnetic shielding, are expected to be among the nearest term
: applications. The company says it hopes it will be facing the need for
: commercial-scale production in 18 to 24 months.
: The company has also found a new home, moving off the Rice campus and
: now leasing office and laboratory space at KBR>s technology center. In
: April, it received funding of $15 million from chemical industry and
: high-technology entrepreneurs Gordon Cain and William McMinn.
: ***************
: Do you know if this project is producing carbon nanotubes (1 kg per day
: by mid-2002) as projected??
: The idea would be then to get a large amount of this material, and then
: attack it like Madame Curie dug into that pile of pitchblende, perhaps
: with a magnetic separation device obtain a small amount of the room
: temperature superconducting material like Seaborg with the plutonium
: microgram on the planchet and then scale up with Manhattan type
: project. This all assumes that the starting material contains the broad
: spectrum of fullerenes from spherical to tubular form and nested inside
: each other in units one to very large.
: Richard Saam PE
: Corpus Christi, Texas
I don>t know much about it yet. I just got here two months ago, and I>m a
theoretician who recently got into gas-phase combustion kinetics. I can
ask around. Can you email me?
--
--
William "Dave" Thweatt
Robert E. Welch Postdoctoral Fellow
Chemistry Department
Rice University
Houston, TX
thweatt@ruf.rice.edu
dave.thweatt@us.army.mil |
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