U.S. patent application number 10/610237 was filed with the patent office on 2004-10-07 for system for manufacture and use of a superconductive coil.
Invention is credited to Dickinson, Charles Bayne.
Application Number | 20040194290 10/610237 |
Document ID | / |
Family ID | 25359874 |
Filed Date | 2004-10-07 |
United States Patent
Application |
20040194290 |
Kind Code |
A1 |
Dickinson, Charles Bayne |
October 7, 2004 |
SYSTEM FOR MANUFACTURE AND USE OF A SUPERCONDUCTIVE COIL
Abstract
In one embodiment, the invention comprises a system for
manufacturing a superconductive electrical conductor. A channel
(140) is formed in a mold (130) that is formed from a ceramic
material having a negative heat coefficient of expansion. A
material (142) having a positive heat coefficient of expansion that
develops superconductivity characteristics upon the application of
heat is deposited in the channel. Heat is applied to the mold (130)
with the material (142) that develops superconductivity
characteristics deposited in the channel to develop the
superconductivity characteristics in the deposited material. In a
particular embodiment, the negative heat coefficient of expansion
and said positive heat coefficient of expansion are complementary,
such that change with heat in dimensions of the channel (140)
formed in the mold (130) and change with heat in dimensions of the
material (142) deposited in the channel (140) are substantially the
same. In a more particular embodiment the channel forms a coil
(22).
Inventors: |
Dickinson, Charles Bayne;
(Bay St. Louis, MS) |
Correspondence
Address: |
E. Eugene Thigpen, Attorney
Post Office Box 42427
Houston
TX
77242
US
|
Family ID: |
25359874 |
Appl. No.: |
10/610237 |
Filed: |
June 30, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10610237 |
Jun 30, 2003 |
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PCT/US02/38658 |
Dec 4, 2002 |
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10610237 |
Jun 30, 2003 |
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09872574 |
Jun 1, 2001 |
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6617738 |
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Current U.S.
Class: |
29/599 ; 335/216;
505/211; 505/230; 505/430 |
Current CPC
Class: |
H02K 55/06 20130101;
Y10T 29/49014 20150115; Y02E 40/627 20130101; Y02E 40/60 20130101;
H02K 31/02 20130101 |
Class at
Publication: |
029/599 ;
505/211; 505/230; 505/430; 335/216 |
International
Class: |
H01L 039/24 |
Claims
1. A method for manufacturing a superconductive electrical
conductor, comprising forming a channel in a mold formed from a
ceramic material having a negative heat coefficient of expansion;
and depositing in said channel a material that develops
superconductivity characteristics upon the application of heat,
said deposited material having a positive heat coefficient of
expansion; and applying heat to said mold having channels with said
material deposited therein to develop said superconductivity
characteristic in said deposited material.
2. The method of claim 1 wherein said negative heat coefficient of
expansion and said positive heat coefficient of expansion are
complementary, such that change with heat in dimensions of the
channel formed in said mold and change with heat in dimensions of
said material deposited in said channel are substantially the
same.
3. The method of claim 1 wherein said channel forms a coil.
4. The method of claim 1 wherein said mold comprises a first
surface and a second surface and said channel extends in a
substantially spiral pattern on said first surface and in a
substantially spiral pattern on said second surface; and wherein
said channel extends between the substantially spiral pattern on
said first surface and said substantially spiral pattern on said
second surface to form a continuous coil, said continuous coil
including the substantially spiral pattern on said first surface
and the substantially spiral pattern on said second surface.
5. The method of claim 1 wherein said mold comprises a first
surface and a second surface and an outer circumferential surface
extending from said first surface to said second surface and an
inner aperture extending from said first surface to said second
surface; and wherein said channel extends in substantially a spiral
pattern in a first direction on said first surface from a first
location at said inner surface to a second location at said outer
circumferential surface, and wherein said channel extends in
substantially a spiral pattern in a second direction on said second
surface from a third location at said inner surface to a fourth
location at said outer circumferential surface, and said channel
extending along said inner aperture from said first location to
said second location and along said outer circumferential surface
from said third location to said fourth location.
6. The method of claim 1 wherein said mold comprises a first
surface and a second surface and an outer circumferential surface
extending from said first surface to said second surface and an
inner surface extending from said first surface to said second
surface and defining an aperture in said mold; and wherein said
channel extends in a substantially spiral pattern on said
circumferential surface from a first location at said first surface
to a second location at said second surface, and wherein said
channel extends along said second surface from said second location
to a third location at said inner surface and along said inner
surface from said third location to a fourth location at said
second surface and along said second surface from said fourth
location to said first location.
7. The method of claim 1 wherein said material that develops
superconductivity characteristics is yttrium barium copper
oxide.
8. The method of claim 1 wherein said ceramic having a negative
heat coefficient of expansion is zirconium tungstate
(ZrW.sub.2O.sub.8).
9. A superconductive electrical conductor, comprising a mold formed
from a ceramic material having a negative heat coefficient of
expansion and having a channel formed therein; and a
superconductive material deposited in said channel, said
superconductive material developing superconductive characteristics
upon the application of heat and having a positive heat coefficient
of expansion.
10. The apparatus of claim 9 wherein said negative heat coefficient
of expansion and said positive heat coefficient of expansion are
complementary, such that change with heat in dimensions of the
channel formed in said mold and change with heat in dimensions of
said material deposited in said channel are substantially the
same.
11. The apparatus of claim 9 wherein said channel forms a coil.
12. The apparatus of claim 9 wherein said mold comprises a first
surface and a second surface and said channel extends in a
substantially spiral pattern on said first surface and in a
substantially spiral pattern on said second surface; and wherein
said channel extends between the substantially spiral pattern on
said first surface and said substantially spiral pattern on said
second surface to form a continuous coil, said continuous coil
including the substantially spiral pattern on said first surface
and the substantially spiral pattern on said second surface.
13. The apparatus of claim 9 wherein said mold comprises a first
surface and a second surface and an outer circumferential surface
extending from said first surface to said second surface and an
inner surface extending from said first surface to said second
surface and defining an aperture in said mold; and wherein said
channel extends in substantially a spiral pattern in a first
direction on said first surface from a first location at said inner
surface to a second location at said outer circumferential surface,
and wherein said channel extends in substantially a spiral pattern
in a second direction on said second surface from a third location
at said inner surface to a fourth location at said outer
circumferential surface, and said channel extending along said
inner surface from said first location to said second location and
along said outer circumferential surface from said third location
to said fourth location.
14. The apparatus of claim 9 wherein said mold comprises a first
surface and a second surface and an outer circumferential surface
extending from said first surface to said second surface and an
inner surface extending from said first surface to said second
surface and defining an aperture in said mold; and wherein said
channel extends in a substantially spiral pattern on said
circumferential surface from a first location at said first surface
to a second location at said second surface, and wherein said
channel extends along said second surface from said second location
to a third location at said inner surface and along said inner
surface from said third location to a fourth location at said
second surface and along said second surface from said fourth
location to said first location.
15. The apparatus of claim 9 wherein said material that develops
superconductivity characteristics is yttrium barium copper
oxide.
16. The apparatus of claim 9 wherein said ceramic having a negative
heat coefficient of expansion is zirconium tungstate
(ZrW.sub.2O.sub.8).
17. A superconductive coil comprising a disk formed from ceramic
material having a first surface and a second surface and an outer
circumferential surface extending from said first surface to said
second surface and an inner aperture extending from said first
surface to said second surface; said disk having a channel
extending in substantially a spiral pattern in a first direction on
said first surface from a first location at said inner aperture to
a second location at said outer circumferential surface, and
extending in substantially a spiral pattern in a second direction
on said second surface from a third location at said inner aperture
to a fourth location at said outer circumferential surface, and
extending along said inner aperture from said first location to
said third location and along said outer circumferential surface
from said second location to said fourth location; and a
superconductive material deposited in said channel forming a
superconductive coil.
18. A superconductive coil comprising a mold having a first surface
and a second surface and an outer circumferential surface extending
from said first surface to said second surface and an inner surface
extending from said first surface to said second surface and
defining an aperture in said mold; a channel extending in a
substantially spiral pattern on said circumferential surface from a
first location at said first surface to a second location at said
second surface, and extending along said second surface from said
second location to a third location at said inner surface and along
said inner surface from said third location to a fourth location at
said first surface and along said first surface from said fourth
location to said first location; and a superconductive material
deposited in said channel forming a superconductive coil.
19. A method for manufacturing an electrically superconductive
coil, comprising: forming a substantially spiral channel in a mold
having a top side and a bottom side, said spiral channel extending
from a first location at a top side of said mold to a second
location at the bottom side of said mold; forming a connective
channel between said first location and said second location; and
depositing a material in said spiral channel and in said connective
channel; said material being superconductive at temperatures below
a critical temperature.
20. The method of claim 19 wherein said material deposited in said
spiral channel is yttrium barium copper oxide.
21. The method of claim 19 wherein said ceramic mold is formed from
zirconium tungstate (ZrW.sub.2O.sub.8).
22. An electrically superconductive coil, comprising: a mold having
a spiral channel formed therein, said spiral channel extending from
a first location at a top side of said mold to a second location at
the bottom side of said mold, and having a connective channel
formed in said mold between said first location and said second
location; and a material deposited in said spiral channel and in
said connective channel; said material being superconductive at
temperatures below a critical temperature.
23. The apparatus of claim 22 wherein said material deposited in
said spiral channel is yttrium barium copper oxide.
24. The apparatus of claim 22 wherein said mold is formed from
zirconium tungstate (ZrW.sub.2O.sub.8).
25. A method for manufacturing an electrically superconductive
coil, comprising: forming a channel in a disk formed from ceramic
material having a first surface, a second surface, an outer
circumference and an aperture extending through said disk, said
channel extending in substantially a spiral pattern in a first
direction on said first surface from a first location at said
aperture to a second location at said outer circumference, and
extending in substantially a spiral pattern in a second direction
on said second surface from a third location at said aperture to a
fourth location at said outer circumference, and extending from
said first location to said third location and from said second
location to said fourth location; and depositing a superconductive
material deposited in said channel, thereby forming a
superconductive coil.
26. The method of claim 25 wherein said material deposited in said
channel is yttrium barium copper oxide.
27. The method of claim 25 wherein said disk is formed from
zirconium tungstate (ZrW.sub.2O.sub.8).
28. A superconductive coil comprising a disk formed from ceramic
material having a first surface, a second surface, an outer
circumference and an aperture extending through said disk, said
disk having a channel extending in substantially a spiral pattern
in a first direction on said first surface from a first location at
said aperture to a second location at said outer circumference, and
extending in substantially a spiral pattern in a second direction
on said second surface from a third location at said aperture to a
fourth location at said outer circumference, and extending from
said first location to said third location and from said second
location to said fourth location; and a superconductive material
deposited in said channel forming a superconductive coil.
29. The apparatus of claim 28 wherein said material deposited in
said channel is yttrium barium copper oxide.
30. The apparatus of claim 28 wherein said disk is formed from
zirconium tungstate (ZrW.sub.2O.sub.8).
31-32 (Canceled).
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation application of PCT Patent
Application PCT/US02/38658, filed on Dec. 4, 2002 in the United
States Receiving Office, from which priority is claimed under 35
USC .sctn. 365(a)-(c). This application is also a
continuation-in-part application of United States Nonprovisional
patent application Ser. No. 09/872,574, filed on Jun. 1, 2001, from
which priority is claimed under 35 USC .sctn. 120.
[0002] PCT Patent Application PCT/US02/16259, filed on May 24, 2002
in the United States Receiving Office, is based on US
Nonprovisional patent application Ser. No. 09/872,574. No priority
is claimed under PCT Patent Application PCT/US02/16259.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0003] Not applicable
BACKGROUND OF THE INVENTION
[0004] Typically, in electrical power plants in operation today,
the prime mover for the generator is a mechanical turbine. The
source of power for the turbine is normally either falling water
obtained from lakes formed by damming rivers, or steam, obtained by
turning liquid water into a gas (steam) by the addition of heat
which may be obtained from the combustion of fossil fuels or
nuclear reactions. Use of other sources of electrical energy, such
as batteries, fuel cells, solar cells, and wind powered generators,
is normally less economical than the use of turbine generators.
[0005] The underlying theory and equations which allowed others to
build machines to convert other forms of energy into electrical
energy were developed by James Maxwell and Michael Faraday. In the
conversion of heat energy into electrical energy, the latent energy
in fossil fuels is first converted into heat energy through the
combustion process. This heat energy is then added to a working
fluid (water) to increase its potential energy. This heat energy is
then converted into mechanical energy by rotating a turbine, which
includes electrically conducting coils, in a magnetic field. The
fundamental principle utilized in producing electrical energy is
that when an electrical conductor (wire) is moved through a
magnetic field, an electrical current will flow through the
conductor. By connecting this conductor to an external device the
electrical current is made to move through the external device,
such as an electrical motor, designed to produce a useful effect,
and return to the generator.
[0006] Massive distribution systems are now required to transport
electricity from the generator to the user. The costs associated
with developing electrical power distribution systems are extremely
high. Moreover, these distributions systems are fragile and need
constant maintenance and repair, and power distribution is
constantly threatened by climatic disruptions and sabotage.
[0007] There is a long felt need for a system for generating
electrical power which is non-polluting. There is also a long felt
need for a system for generating electrical power which does not
require a massive distribution system of electrically conducting
wires. There is also a long felt need for improvement in
manufacturing processes for high temperature superconductive
materials for application to many technical fields.
[0008] It should be noted that the description of the invention
which follows should not be construed as limiting the invention to
the examples and preferred embodiments shown and described. Those
skilled in the art to which this invention pertains will be able to
devise variations of this invention within the scope of the
appended claims.
SUMMARY OF THE INVENTION
[0009] In one embodiment, the invention comprises a system for
manufacturing a superconductive electrical conductor. A channel is
formed in a mold that is formed from a ceramic material having a
negative heat coefficient of expansion. A material having a
positive heat coefficient of expansion that develops
superconductivity characteristics upon the application of heat is
deposited in the channel. Heat is applied to the mold with the
material that develops superconductivity characteristics deposited
in the channel to develop the superconductivity characteristics in
the deposited material. In a particular embodiment, the negative
heat coefficient of expansion and said positive heat coefficient of
expansion are complementary, such that change with heat in
dimensions of the channel formed in the mold and change with heat
in dimensions of the material deposited in the channel are
substantially the same. In a more particular embodiment the channel
forms a coil.
[0010] In yet another embodiment, the invention comprises a system
for initiating superconductive current flow in a coil formed from
material that is superconductive below a certain temperature. The
coil is immersed in a cryogenic fluid to cool the coil below its
superconductive temperature. Heat is applied to a first segment of
the coil to maintain the first segment above a superconductive
temperature. A current flow is established in a second segment of
the coil from a source of electric current. After the second
segment becomes superconductive, the application of heat to said
first segment is discontinued, thereby allowing the first segment
to cool below the superconductive material and establishing
superconductive current flow within the first and second segment of
the coil.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 shows a diagram in partial cross-section of a
generator in accordance with a preferred embodiment of the
invention
[0012] FIG. 2A shows a cross-sectional side view of a prime mover
comprising a plurality of spaced-apart disks.
[0013] FIG. 2B shows a top view of a prime mover comprising a
plurality of spaced-apart disks.
[0014] FIG. 3A shows a top view of an implementation of a
superconductive coil.
[0015] FIG. 3B shows a side view of an implementation of a
superconductive coil FIG. 3C is a perspective view of a segment of
the superconductive coil.
[0016] FIG. 4 illustrates in schematic form the generation of a
current in a Faraday disk.
[0017] FIG. 5 illustrates the application of the invention to the
operation of an automobile.
[0018] FIG. 6 illustrates the application of the invention for
supplying electrical power to a residence.
[0019] FIGS. 7A, 7B and 7C show an embodiment of a superconductive
coil.
[0020] FIG. 8 shows a system for initiating current flow in a
superconductive coil.
DESCRIPTION OF PREFERRED EMBODIMENT
[0021] FIG. 1 shows a diagram of an electrical power generator 10
in accordance with a preferred embodiment of the invention. In a
preferred embodiment of the invention, power for the prime mover is
derived from the conversion of a cryogenic fluid from a liquid to a
gas under pressure. The term "cryogenic fluid" is intended to mean
a substance which is gaseous at temperatures typically found at the
earth's surface, but which may be liquified at lower temperatures.
Although nitrogen may be a more practical cryogenic fluid for
implementing the invention, those of ordinary skill in the art will
understand that other gases which liquify at low temperatures, such
as hydrogen or helium, may be utilized in implementing the
invention.
[0022] Seventy-eight percent of the earth's atmosphere is gaseous
nitrogen. Therefore, nitrogen is available at any point on the
earth in unlimited amounts. Nitrogen becomes a liquid at about
minus 321 degrees Fahrenheit (-321.degree. F.), which is about
seventy seven degrees Kelvin (77.degree. K). When heat is added to
liquid nitrogen to convert it into a gas, the volume of the
nitrogen expands by a factor of about 850/1; that is, a one cubic
inch volume of liquid nitrogen becomes about 850 cubic inches of
gaseous nitrogen at 77.degree. K. If heat is then added to this one
(1) cubic inch volume and the temperature is increased from
77.degree. K to an ambient temperature of 288.degree. K, the
pressure of the nitrogen will be about 80 pounds per square inch
gage (psig). Accordingly, the thermal energy which is added to the
nitrogen may be released to produce a mechanical motion. In
accordance with a preferred embodiment of the present invention
this produced mechanical motion is utilized to produce electrical
power.
[0023] In one embodiment of the invention, yttrium barium copper
oxide is used as the superconducting material. However, other
superconducting material, including but not limited to thallium
barium calcium copper oxide and bismuth strontium calcium copper
oxide, may be utilized so long as the temperature at which the
material becomes superconductive is higher than the temperature at
which the cryogenic fluid becomes liquid.
[0024] The liquid nitrogen 14 is contained in cryogenic container
12 and superconducting coil 22 is immersed in the liquid nitrogen.
As heat is absorbed by the liquid nitrogen, the liquid nitrogen
initially boils off as gaseous nitrogen 16, which collects at the
top of cryogenic container 12. When the pressure of the gaseous
nitrogen increases to a selected level, it will activate pressure
regulator 28, which permits gaseous nitrogen to flow, under
pressure, through conduit 26 and 30 and nozzles 58, to the prime
mover 24.
[0025] As shown in FIGS. 2A and 2B, in a preferred embodiment,
prime mover 24 is a turbine comprising a plurality of disks,
mounted closely together in substantially parallel planes. The
gaseous nitrogen flows between these disks and induces rotational
motion of the prime mover. Prime mover 24 is mounted on disk
element 32, which is mechanically coupled to Faraday disk 44
through shaft 38, through which rotational motion of the prime
mover 24 is coupled to Faraday disk 44. Faraday disk 44, which may
be formed from copper or other highly conductive material, rotates
within the magnetic field developed by electrical current
circulating in coil 22. As a result of the rotation of the Faraday
disk through the magnetic field, a voltage is generated between the
center and the outer edge of the Faraday disk. As described further
below, current flows from the Faraday disk to a user of electrical
energy and back to the Faraday disk through electrical conductors
applied to the center and outer edge of the Faraday disk.
[0026] Liquid nitrogen, denoted by numeral 14, is contained within
cryogenic container 12, which may comprise a conventional Dewar
type vessel 11 and cryogenic barrier 18, which forms the top of
cryogenic container 12. Dewar type vessel 11 may be a conventional
double walled container with a vacuum or a low thermal conductivity
material between the walls. Note that FIG. 1 is drawn for the
purpose of illustrating the invention and is not intended to be a
scale drawing. Cryogenic barrier 18, which forms the top of the
cryogenic container 12 would typically be much smaller in relation
to vessel 11 than is shown is FIG. 1. Container 12 is configured
for maintaining superconductive coil 22 submerged in the liquid
nitrogen. The container 12 must be sealed and of sufficient
mechanical strength to withstand the pressure build-up of the
gaseous nitrogen as the liquid nitrogen boils off.
[0027] FIG. 1 shows conduit 20, through which liquid nitrogen may
be added to cryogenic container 12 from an external source (not
shown) of liquid nitrogen. Conduit 20 may be conventional cryogenic
tubing known to those of ordinary skill in the art. Also shown is
level sensor 40 and the cryogenic valve 48 that level sensor 40
controls. When level sensor 40 detects that the level of the liquid
nitrogen has fallen below a selected level, level sensor 40 opens
cryogenic valve 48 to allow additional liquid nitrogen to flow into
cryogenic container 12 from the external liquid nitrogen source.
This level is selected to keep the superconductive coil 22
submerged in the liquid nitrogen in order to maintain the
superconductivity of the coil. Level sensor 40 is operatively
connected to cryogenic valve 48, typically through an electrically
conducting wire 21.
[0028] In a preferred embodiment, power is generated by rotating a
Faraday disk 44 in a magnetic field resulting from current flow
through coil 22. Power for rotating the Faraday disk is generated
by the absorption of heat by the liquid nitrogen, which converts a
portion of the liquid nitrogen 14 into gaseous nitrogen. Although
cryogenic barrier 18 will have low thermal conductivity, the
material forming cryogenic barrier 18 is chosen to conduct a
limited amount of heat into the liquid nitrogen chamber for
converting the liquid nitrogen to a gas at a controlled rate.
Because the nitrogen is confined in cryogenic container 12,
pressure will increase in this space as the liquid is converted to
a gas. The gaseous nitrogen is held in the cryogenic container
until a desired operating pressure is reached. Pressure regulator
28 is set to open at the desired operating pressure so that the
gaseous nitrogen flows from conduit 26 to conduit 30 and then
through nozzles 58. As the gaseous nitrogen is propelled through
the nozzles 58 it reaches a very high velocity (typically 330
meters per second at about 15 psig, or greater at higher
pressures). This high velocity gas now flows through the prime
mover 24 and into the center space 54 within the prime mover, and
then out to the atmosphere through exhaust conduit 56. As discussed
below, the gaseous flow through prime mover 24 causes rotational
motion of the prime mover. This rotational motion is then
transferred through shaft 38 to Faraday disk 44.
[0029] As shown in FIG. 1, safety valve 29 may be included in the
gaseous nitrogen flow path so that if for any reason the pressure
within cryogenic container 12 exceeds a selected maximum pressure,
safety valve 29 will open and release gaseous nitrogen into the
atmosphere.
[0030] The electrical energy output of the generator 10 is
proportional to the intensity of the magnetic field produced by
superconducting coil 22, which is proportional to the current flow
in the coil 22. Because the current flow that can be generated in a
superconducting coil is much greater than the current flow that can
be generated in a conventional wire, a much more powerful magnetic
field can be produced by a superconducting coil than by
conventional wire. A particularly advantageous feature of
superconducting coils is their ability to sustain an electrical
current in the coil without additional electrical input as long as
the coil is below the critical temperature of the superconductive
material from which the coil is made. Therefore, once the
electrical current has started to flow in the coil, the input
connections to the coil can be "shorted" together and, provided the
temperature of the coil is maintained below its critical
(superconducting) temperature, the current will continue to flow in
the coil for very long periods of time. Because of the availability
of liquid nitrogen, a high temperature superconducting coil is
especially useful for producing the magnetic field in the generator
portion of the machine.
[0031] An advantageous mechanical feature of a preferred embodiment
of the invention is that the liquid nitrogen which is utilized for
maintaining the magnetic field producing coil at a superconducting
temperature may also be utilized for developing the mechanical
energy for operating the generator. Although a preferred embodiment
of the invention is described in terms of using the evaporating
cryogenic fluid from cryogenic container 12 for driving the prime
mover 24, those of ordinary skill in the art will understand that
the gaseous stream which drives the prime mover may be obtained
from a source other than the container in which the cryogenic fluid
is stored for maintaining the superconductive coil 22 at a
superconducting temperature. For example, the source of the gaseous
stream could be another container of evaporating cryogenic
fluid.
[0032] A conductive coil, which may be made from a high temperature
surperconductive material, such as yttrium barium copper oxide
(YBCO), is preferably immersed within liquid nitrogen. Accordingly,
superconductive coil 22 is shown mounted on a portion of cryogenic
barrier 18 which extends downwardly into the cryogenic container
12, so that in normal operation, coil 22 will be immersed in the
liquid nitrogen, or other cryogenic fluid. Typically, the upper
portion of cryogenic container 12 will contain gaseous nitrogen,
which is designated by numeral 16 in FIG. 1. The superconductive
coil may be cemented to the cryogenic barrier 18 as shown, but it
can be fastened within cryogenic container 12 in any manner that
will maintain the coil 22 in a stable position relative to Faraday
disk 44. Those of ordinary skill in the art will understand that
the mechanism used for holding coil 22 in place must be able to
withstand the temperature of the liquid nitrogen, or other
cryogenic fluid utilized.
[0033] The construction of a first implementation of the coil 22 is
shown in FIGS. 3A, 3B and 3C. Because of the difficulty in forming
a wire from yttrium barium copper oxide (YBCO) and other
superconductive material, the coil may be formed within a mold
comprising ceramic loop 70, as shown in FIGS. 3A and 3B. Spiral
groove 72 may be cut into ceramic form 70, which may extend to a
depth location 74 within the ceramic loop. This spiral groove is
shown reaching the top surface of ceramic loop 70 at location 76,
and reaching the bottom of ceramic loop 70 at location 78. The
superconducting coil is formed by filling the spiral groove 72 with
the superconductive material. In order to connect the upper end of
the spiral loop at location 76 to the lower end of the spiral loop
at location 78, a connective groove 80 may be formed in the ceramic
form 70 extending from location 76, down the interior side of
ceramic form 70, to location 78, as shown in FIG. 3C. By filling
this connective groove 80 with the superconductive material, the
upper end 76 and the lower end 78 of the spiral loop are joined
together to form a superconductive coil.
[0034] Also shown in FIG. 3C is a small resistance heater 82
mounted in juxtaposition to connective link 80. As explained below,
to initiate operation of the system, a battery (not shown) is
connected between terminal 84, which is electrically connected to
location 76 and one end of resistance heater 82, and terminal 86,
which is electrically connected to location 78 and the other end of
resistance heater 82.
[0035] The construction of another implementation of the coil 22 is
shown in FIGS. 7A, 7B and 7C. FIGS. 7A, 7B and 7C show a ceramic
form 130 (also referred to herein as a mold), which may be a disk,
into which a superconductive coil is constructed according to an
embodiment of the present invention. FIG. 7A shows a first surface
132 of the disk, which may be referred to herein as the top
surface. FIG. 7B shows a side view and FIG. 6C shows a second
surface 135 of the disk, which may be referred to herein as the
bottom surface. A circumferential surface 134 extends from the
first surface to the second surface, as shown in FIG. 7B. As also
indicated in FIGS. 7A, 7B and 7C, an aperture 136 extends through
the interior of the disk, with an inner surface of the aperture
extending from the first surface 132 to the second surface 135.
Although a preferred embodiment is described in terms of a disk,
the invention may comprise other forms having a first surface and a
second surface, which preferably are substantially parallel, with a
circumferential surface (or edge) and an internal aperture surface
extending between the first and second surfaces.
[0036] Grooves 140 are preferably cast into ceramic form 130 when
the ceramic form is manufactured. Alternatively, the grooves 140
may be milled, or otherwise formed, into the form 130 after it is
manufactured. In either event, the grooves 140 are formed in a
continuous pattern on the first surface 132 and second surface 135
extending substantially from the internal aperture 136 to the outer
circumference (outer edge), preferably in a generally spiral
pattern. On a first (or top) surface 132 of the disk, the spiral
goes in a first direction, which may be a clockwise (rightward)
projection, extending from location 140B at substantially the
outside edge (the outer circumference) of the surface to location
140A at the internal aperture 136 of the disk. On the second (or
bottom) surface 135 of the disk as shown in FIG. 7C, the spirals
are in the reverse direction, which may be a counterclockwise (or
leftward) orientation, and extend from location 140C at
substantially the outside edge (the outer circumference) to
location 140D at the internal aperture 136 of disk 130. The purpose
of the leftward orientation on the second (bottom) surface and the
rightward orientation on the first (top) surface is to facilitate
the assembly of a continuous coil. A superconductive material 142,
which may be yttrium barium copper oxide is deposited into groove
140 on surfaces 132 and 135 and also into the segment of groove 140
extending along the internal aperture 136 from location 140A on
surface 132 to location 140D on surface 135, and along the outer
circumferential surface 134 of the disk from location 140B on
surface 132 to location 140C on surface 135, to complete the
coil.
[0037] To form either implementation of the superconductive coil
depicted in FIGS. 3A, 3B and 3C or in FIGS. 7A, 78B and 7C, a
material 142, which may be a high temperature superconductive (HTS)
ceramic material that develops superconductive characteristics upon
the application of heat is deposited into the grooves 140 in a
"raw" state. By "raw" state is meant in the state before heat is
applied to develop the superconductive characteristic. The entire
assembly (the mold 130 with the HTS ceramic material 142 deposited
in groove 140) is then placed in a conventional heat-treatment
furnace (not shown) where both the ceramic form (mold) 130 and the
HTS ceramic material 142 undergo the heat treatment that produces
the superconductive effect in the HTS ceramic material. By using a
ceramic material for the form (mold) that has a negative
coefficient of thermal expansion, for example zirconium Tungstate
(ZrW.sub.2O.sub.8), matched to the positive coefficient of thermal
expansion of the HTS ceramic material (for example, yttrium barium
copper oxide), the detrimental effect of thermal stress (the
tendency for the HTS material to develop a different shape from the
mold in which it is being formed, and to crack) can be
substantially reduced.
[0038] FIG. 8 illustrates a second embodiment of a circuit,
referred to herein as a persistence switch, useful in initiating
superconductive current flow in coil 22, the operation of which is
explained more fully hereinafter.
[0039] The methods for fabricating a superconductive electrical
conductor described with reference to FIGS. 3A, 3B and 3C and FIGS.
7A, 7B and 7C are equally applicable to the fabrication of
superconductive electrical conductors for applications other than
for implementing the generator described with reference to FIG.
1.
[0040] As shown more clearly in FIGS. 2A and 2B, in a preferred
embodiment, prime mover 24 comprises a plurality of disks 23, which
may be made from a high strength aluminum alloy. These disks are
affixed together in axial alignment in spaced apart positions, in
substantially parallel planes. In one implementation of the
invention these disks are affixed together by bolt assemblies 62,
which may comprise shoulder bolts. Bolt assemblies 62 may include
spacers 64, as shown in FIG. 2A, between each of the disks 23. In a
particular implementation of the invention, bolt assemblies 62 also
affix the prime mover 24 to support disk 32. FIGS. 2A and 2B show
four bolt assemblies 62, however, a different number of bolt
assemblies may be utilized. The number of disks 23, the spacing
between the disks and the dimensions of the disks may also vary,
depending on the required power output, mechanical ruggedness and
other design criteria which may be applicable to a particular
implementation of the invention.
[0041] Rotational movement of prime mover 24 is generated by the
flow of the gaseous nitrogen from conduit 30 through one or more
high velocity nozzles 58 and through the space between the disks 23
of the prime mover 24. The gaseous stream will typically be
projected by the nozzles in a direction which is substantially
tangential to the edges of the disks 23. The nozzles may be
machined into the wall of the housing structural member 50 within
which the disks 23 rotate, rather than separate items connected to
the end of conduit 30. The nozzles 58 may substantially increase
the velocity of the gaseous nitrogen stream The disks 23 are
closely spaced apart so that the gaseous flow through the spaces
between the disks 23 will drag the disks in the direction of the
gaseous flow, and since prime mover 24 is mounted, via support disk
32, onto shaft 38, rotational motion of the disks 23 included in
the prime mover is generated. Rotational speed of the prime mover
assembly increases until the surface speed of the outside edge of
the disks 23 reaches almost the same velocity as that of the
gaseous jet emanating from the nozzles 58. To increase the power
produced by this prime mover assembly, the number of disks 23 and
nozzles 58 may be increased, and the volume of nitrogen flow may be
increased accordingly. The gas flow across the surface of the disks
23 drags the disk surfaces along the direction of the gas flow.
This action takes place in a "layer" of the gas next to the disk
surface. It has been called the "boundary" between the gas and the
geometrical surface, hence "boundary layer" effect.
[0042] Although a preferred embodiment of the invention has been
described in terms of a prime mover comprising a plurality of
closely spaced, parallel, coaxially mounted disks, those of
ordinary skill in the art will recognize that a bladed turbine may
also be utilized in implementing the invention, as well as other
more conventional prime movers which operate on gas expansion.
[0043] The rotational motion of prime mover 24 is transferred to
the Faraday disk 44 through shaft 38. Shaft 38 comprises a
bolt-like unit, which may be secured to support disk 32 by nut unit
36 in a conventional nut and threaded shaft configuration. Shaft 38
and nut unit 36 may each be made from stainless steel, copper or
other material having similar qualities of strength and ruggedness.
Nut 36 may be shaped to facilitate flow of gas from the prime mover
through exhaust port 56. Shaft 38 may be fixedly connected to
Faraday disk 44 by brazing, or by a threaded connection or other
means known to those of ordinary skill in the art. Shaft 38 and
Faraday disk 44 may also be machined as a unitary structure.
Bearing 42 is positioned between shaft 38 and housing structural
member 50, to maintain the shaft in alignment and to permit
rotational movement of the shaft 38 in sliding engagement with
bearing 42. In a particular embodiment bearing 42 may also be
configured to extend into the space between support disk 32 and
structural member 50, so provide clearance so that support disk 32
can rotate freely. In a preferred embodiment, bearing 42 is made
from electrically conductive material in order to conduct
electrical current which flows through shaft 38 from the center of
the Faraday disk. Bearing 42 may be formed from graphalloy, or
other material having similar qualities of low thermal expansion,
high electrical conductivity and low surface friction.
[0044] Faraday disk 44 is mounted in sliding engagement within
bearing 46. In a preferred embodiment, bearing 46 is made from
electrically conductive material in order to conduct current into
(or from) the outer edge of the Faraday disk. Bearing 46 may be
formed from graphalloy, or other material having similar qualities
of low thermal expansion, high electrical conductivity and low
surface friction. In a preferred embodiment, bearings 42 and 46
provide a means for transmitting electrical energy from the Faraday
disk to an external electrical load, as well as a suitable low
friction bearing for the shaft 38 and the Faraday disk 44.
[0045] As shown schematically in FIG. 4, Faraday disk 44, which may
be made from copper or other highly conductive material, rotates
through the magnetic flux lines 60 resulting from current flow in
coil 22. In accordance with a preferred embodiment of the present
invention, an intense magnetic field is produced through the use of
the superconducting coil. Induction occurs as a magnetic field is
changing strength. In accordance with a preferred embodiment of the
invention, the rotating portion of electric power generator 10
moves in relation to the stationary magnetic field and hence
produces an electrical current. FIG. 4 illustrates in schematic
form the generation of a current in a Faraday disk. The magnetic
lines of flux denoted by the letter "B", are shown flowing through
the Faraday disk, which is indicated to be rotating in a
counterclockwise direction. This rotational movement of the Faraday
disk generates an electrical voltage, V, between the center point
of the disk, and its outer edge. By positioning a first electrode
in contact with the center point of the disk and a second electrode
at the outer edge of the disk, a current flow is generated. In the
embodiment shown in FIG. 1, bearing 42 is the first electrode and
bearing 46 is the second electrode.
[0046] It is well known to those of ordinary skill in the art that
the power that may be produced by a Faraday disk is governed by the
following formulas:
V=sB (Eq. 1)
[0047] where: V=voltage developed across the Faraday disk
[0048] s=rotational speed of disk in revolutions per second,
and
[0049] B=magnetic flux in Teslas. 1 I = V r ( Eq . 2 )
[0050] where:
[0051] I=current in amperes
[0052] V=voltage developed across the Faraday disk
[0053] r=resistance of external load in ohms
[0054] and:
W=IV (Eq. 3)
[0055] where W=output power in watts
[0056] I=current in amperes
[0057] V=voltage developed across the Faraday disk.
[0058] Although a preferred embodiment of the invention has been
described in terms of using a Faraday disk for generation of
electrical power, those of ordinary skill in the art will
understand that other electrical conductor configurations may be
utilized. For example, an electrically conducting coil
configuration typical of the electrical conducting coils normally
used in electrical power generation system could be rotated in the
magnetic field generated by the superconducting coil for generating
output power.
[0059] With reference to FIGS. 3A, 3B and 3C, electrical power
generator 10 may be powered up as follows. Once the cryogenic
container 12 has been filled with liquid nitrogen and level sensor
40 has closed cryogenic valve 48 and stopped the flow of liquid
nitrogen into the cryogenic container 12, electrical energy is
supplied to coil 22. As stated above in the discussion with respect
to FIG. 3C, this electrical energy may be supplied from a battery
(not shown) which is connected between terminals 84 and 86. The
voltage and current capacity of the battery is selected in
accordance with the desired current flow into superconducting coil
22. Typically, the battery will be connected to terminals 84 and 86
by means of electrically conducting wires which will pass through a
conduit (not shown) in cryogenic container 12.
[0060] As previously stated, resistance heater 82 is connected
between terminals 84 and 86, and when a battery is connected across
terminals 84 and 86, current will flow through coil 22 and through
resistance heater 82. Resistance heater 82 is positioned in
juxtaposition to connective link 80, and will maintain connective
link 80 at a temperature above its superconductive temperature.
Normally, as current begins to flow from the battery through the
superconductive coil 22 and back to the battery, the temperature of
the coil 22 will be above its critical (i.e., superconductive)
temperature. When the coil 22, which is immersed in liquid
nitrogen, reaches a temperature below its superconductive
temperature, the coil becomes superconductive, and the voltage
across terminals 84 and 86 will drop to substantially zero, and the
electrical power to the resistance heater is thereby substantially
removed. The connective link 80 will then cool to a temperature
below its critical temperature and connective link 80 will become
superconductive. A superconductive coil has now been formed, with a
flow path connecting the beginning of the coil at location 76 to
the end of the coil at location 78. The battery may now be
disconnected, and the electrical current will continue to flow in
coil 22 without any additional current needed from the battery as
long as the coil is kept at or below the critical (superconducting)
temperature of the material form which the coil is formed
[0061] With reference to FIGS. 7A, 7B, 7C and 8, in an alternate
embodiment, electrical power generator 10 may be powered up as
follows. Once the cryogenic container 12 has been filled with
liquid nitrogen and level sensor 40 has closed cryogenic valve 48
and stopped the flow of liquid nitrogen into the cryogenic
container, switch 110 is closed, and an electrical source 114,
which may be a battery, is connected across terminals 116 and 118
of resistor 112, and an electrical current is caused to flow
through resistive heater 112. Resistive heater 112 is placed in
proximity to a segment of coil 22, shown in FIG. 8 as segment 128.
As coil 22 is cooled by the cryogenic fluid, the segment 128 of
coil 22 adjacent heater 112 is maintained above the
surperconductive temperature of the coil. As segment 124 of coil 22
(the portion of superconductive coil 22 that is not heated by
heater element 112) cools below the superconductive temperature,
switch 110 is opened, removing the current flow through resistor
112, and switch 126 is closed, thereby applying electrical source
114 across terminals 122 and 120 and initiating current flow from
current source 114 through segment 124 of coil 22. Although the
electrical source 114 is also applied across coil segment 128,
initially the current flow through coil segment 128 will be limited
because the heat from resistive heater 112 will maintain segment
128 above its superconductive temperature. However, as segment 128
cools and becomes superconductive, the current will begin to flow
from coil segment 124 through segment 128, thereby establishing a
surperconductive current loop throughout superconductive coil 22.
Switch 126 may then be opened (or the battery 114 may be removed)
and the current will continue to flow through superconductive coil
22.
[0062] As the liquid nitrogen in cryogenic container 12 absorbs
heat, the liquid nitrogen is continually boiled off to produce
gaseous nitrogen. The process of absorption of heat energy from the
environment is a process that depends on the difference in
temperature between the environment and the liquid nitrogen and the
quality of heat conductive paths between the environment and the
liquid nitrogen. Heat flows toward the lowest temperature. Hence,
the heat from the earth will by nature flow toward the liquid
nitrogen and boil the nitrogen, and then continue to heat the
gaseous nitrogen until the gaseous nitrogen reaches the ambient
temperature on the earth at the location of the generator. The
thermal design of electrical power generator 10 will control the
rate at which heat flows to the liquid nitrogen. Accordingly, the
thermal capabilities of the generator may be designed to
accommodate the heat flow required to provide the power desired
from the machine.
[0063] Electrical insulating barrier 13 is fabricated from
electrically non-conducting material in order to form an electrical
barrier between the cryogenic barrier 18 and element 50. Electrical
insulating barrier 13 also functions as a structural element to
secure structural element 50 and graphalloy bearing 42 in position.
Element 50 is formed of an electrically conducting material, such
as stainless steel or copper, and is electrically connected through
the graphalloy bearing 42 and shaft 38 to the center of Faraday
disk 44. Cryogenic barrier 18 is connected through graphalloy
bearing 46 to the outer edge of Faraday disk 44. Electrical
insulating element 13 provides electrical insulation between
cryogenic barrier 18 and element 50. Current developed by the
Faraday disk is conveyed from the center of the Faraday disk,
through shaft 38, graphalloy bearing 42, structural element 50 and
through a first electrical conductor (not shown) to an external
electrical power user. The return current path is through a second
electrical conductor (not shown), cryogenic barrier 18 and
graphalloy bearing 46 to the outer edge of Faraday disk 44. Element
50 also provides a housing for the prime mover. Element 52 closes
the housing and provides an exhaust port for the spent gaseous
nitrogen.
[0064] The upper portions of the machine, comprising cryogenic
barrier 18, electrical insulating barrier 13, structural member 50,
and exhaust cover 52 may also function as heat exchangers in
addition to providing the mechanical structure of the machine. In
addition, in one embodiment of the invention sufficient resistivity
may be built into cryogenic barrier 18 so that as the power output
demand from the generator increases and the current flow through
cryogenic barrier 18 increases, the heat generated in cryogenic
barrier 18 will increase accordingly, thereby providing a
proportionate increase in the rate of conversion of the liquid
nitrogen to gaseous nitrogen for driving the prime mover. If it is
anticipated that a generator may be required to provide power over
wide power output range, additional heat exchangers may be included
as a part of the generator.
[0065] Uses for the invention may include but are not limited to
supplying power for operating an automobile and supplying power to
operate the electrical appliances and equipment found in a personal
residence. FIG. 5 illustrates the use of the invention for
supplying power to an automobile 96. A liquid nitrogen storage
unit, designated by numeral 90, supplies liquid nitrogen to the
generator 92, which is substantially similar to generator 10
described with reference to FIG. 1. Gaseous liquid nitrogen is
exhausted through conduit 100. The output of the generator 92
supplies the power to the vehicle control and propulsion system 94,
which may be similar to the control and propulsion system utilized
in prior art electrically powered automobiles. Depending on the
output voltage level from generator 92, the generator may
optionally be applied to a converter 98, to convert the output of
the generator to the appropriate voltage level for operating the
automobile. Such converters are well known to those of ordinary
skill in the art and will not be described in detail herein
[0066] FIG. 6 illustrates the use of the invention for supplying
power to a residence. As shown in FIG. 6, liquid nitrogen is
supplied from liquid nitrogen storage unit 104 to the generator
106, whose construction is substantially similar to generator 10
described with reference to FIG. 1. The output of generator 106 is
supplied to converter 108, which converts the output from generator
106 to the frequency and voltage required for running a residential
electrical system, which typically is 120 or 240 volts, at 50 or 60
Hz. frequency. Such converters are well known to those of ordinary
skill in the art and will not be described in detail herein.
[0067] It will be appreciated that various modifications,
alternatives, variations, and changes may be made without departing
from the scope of the invention as defined in the appended claims.
It is intended to cover by the appended claims all such
modifications involved within the scope of the claims.
* * * * *