U.S. patent application number 10/702968 was filed with the patent office on 2004-09-30 for heat pipe system for cooling flywheel energy storage systems.
Invention is credited to Gernert, Nelson J., Lindemuth, James E., Mast, Brian E., Smith, James L. JR., Todd, John J. JR..
Application Number | 20040188059 10/702968 |
Document ID | / |
Family ID | 25508379 |
Filed Date | 2004-09-30 |
United States Patent
Application |
20040188059 |
Kind Code |
A1 |
Todd, John J. JR. ; et
al. |
September 30, 2004 |
Heat pipe system for cooling flywheel energy storage systems
Abstract
A system for cooling a canister has first, second and third heat
pipes. The first heat pipe has an evaporator and a condenser. The
first heat pipe is mounted with its evaporator inside the canister
and its condenser outside the canister. The second heat pipe has an
evaporator conductively coupled to the condenser of the first heat
pipe. The second heat pipe has a condenser. The third heat pipe has
an evaporator conductively coupled to the condenser of the second
heat pipe. The third heat pipe has a condenser with a plurality of
fins on the condenser of the third heat pipe.
Inventors: |
Todd, John J. JR.;
(Elizabethtown, PA) ; Lindemuth, James E.;
(Lancaster, PA) ; Mast, Brian E.; (Lancaster,
PA) ; Gernert, Nelson J.; (Elizabethtown, PA)
; Smith, James L. JR.; (Lititz, PA) |
Correspondence
Address: |
DUANE MORRIS LLP
P. O. BOX 1003
305 NORTH FRONT STREET, 5TH FLOOR
HARRISBURG
PA
17108-1003
US
|
Family ID: |
25508379 |
Appl. No.: |
10/702968 |
Filed: |
November 6, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10702968 |
Nov 6, 2003 |
|
|
|
09964303 |
Sep 26, 2001 |
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Current U.S.
Class: |
165/45 ;
165/104.26 |
Current CPC
Class: |
F28D 15/046 20130101;
F25B 2500/01 20130101; F25B 23/006 20130101; F28D 15/0275 20130101;
H02K 7/025 20130101; H02K 9/00 20130101 |
Class at
Publication: |
165/045 ;
165/104.26 |
International
Class: |
F28D 001/00 |
Claims
What is claimed is:
1. A system comprising: a flywheel stored within a canister; and a
heat pipe having an evaporator and a condenser, the heat pipe being
mounted with the evaporator inside the canister and the condenser
outside the canister; and means for dissipating heat from the
condenser of the heat pipe.
2. A system comprising: a first heat pipe having an evaporator and
a condenser, the first heat pipe being mounted with the evaporator
inside the canister and the condenser outside the canister; a
second heat pipe having an evaporator thermally coupled to the
condenser of the first heat pipe, the second heat pipe having a
condenser; and means for dissipating heat from the condenser of the
second heat pipe.
3. A system comprising: a flywheel stored within a canister; and a
heat pipe having an evaporator and a condenser, the heat pipe being
mounted with the evaporator inside the canister and the condenser
abutting a wall of the canister.
4. A system for cooling a canister, comprising: a first heat pipe
having an evaporator and a condenser, the first heat pipe being
mounted with the evaporator inside the canister and the condenser
outside the canister; a second heat pipe having an evaporator
thermally coupled to the condenser of the first heat pipe, the
second heat pipe having a condenser; a third heat pipe having an
evaporator thermally coupled to the condenser of the second heat
pipe, the third heat pipe having a condenser; and means for
dissipating heat from the condenser of the third heat pipe.
5. The system of claim 4, wherein the canister is at least
partially buried below ground, and the first heat pipe is
positioned entirely below a ground surface.
6. The system of claim 4, wherein the second heat pipe is partially
buried below the ground surface, and partly above the ground
surface.
7. The system of claim 4, wherein the third heat pipe is completely
above the ground surface.
8. The system of claim 4, wherein the second heat pipe is a
thermosyphon.
9. The system of claim 4, wherein the evaporator of the third heat
pipe is oriented substantially vertically, and the condenser of the
third heat pipe is at a substantial angle away from vertical.
10. The system of claim 9, wherein the angle of the condenser of
the third heat pipe is at least about 5 degrees from
horizontal.
11. The system of claim 4, wherein the first heat pipe is mounted
to a motor housing of a flywheel system within the canister.
12. The system of claim 11, wherein the first heat pipe is mounted
within a block of metal having a hole therethrough to receive the
heat pipe, the block being mounted to the flywheel system.
13. The system of claim 4, wherein the canister is a vacuum
housing.
14. The system of claim 4, wherein the heat dissipating means
including a plurality of circular fins arranged in a fin stack.
15. The system of claim 4, wherein at least one of the heat pipes
has a wick in the evaporator thereof that does not extend into the
condenser thereof.
16. The system of claim 4, wherein at least one of the heat pipes
has a wick formed of sintered metal.
17. An energy storage system, comprising: a canister; an energy
storage flywheel having a motor housing mounted inside the
canister; a first heat pipe having an evaporator and a condenser,
the evaporator of the first heat pipe being mounted to the motor
housing, the condenser of the first heat pipe outside the canister;
a second heat pipe having an evaporator conductively coupled to the
condenser of the first heat pipe, the second heat pipe having a
condenser; a third heat pipe having an evaporator conductively
coupled to the condenser of the second heat pipe, the third heat
pipe having a condenser interfacing to a heat dissipating
means.
18. The system of claim 17, wherein the second heat pipe is a
thermosyphon.
19. The system of claim 17, wherein the evaporator of the third
heat pipe is oriented substantially vertically, and the condenser
of the third heat pipe is at a substantial angle away from
vertical.
20. The system of claim 19, wherein the angle of the condenser of
the third heat pipe is at least about 5 degrees from
horizontal.
21. The system of claim 17, wherein the canister is a vacuum
housing.
22. The system of claim 17, wherein the heat dissipating means
include circular fins arranged in a fin stack.
23. The system of claim 17, wherein at least one of the heat pipes
has a wick in the evaporator thereof that does not extend into the
condenser thereof.
24. The system of claim 17, wherein at least one of the heat pipes
has a wick formed of sintered metal.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to cooling systems generally,
and more specifically to heat pipe systems.
BACKGROUND OF THE INVENTION
[0002] Flywheel systems are used for energy storage in backup power
supplies (e.g., for telecommunication systems, server farms, etc.).
Energy is stored in the angular momentum of the flywheel. The
flywheel systems are typically stored inside silo canisters, and
these canisters can be located above or below ground. Typical
prior-art flywheel systems dissipated a sufficiently small amount
of waste heat that the canister could be cooled by passive
conduction from the canister to the exterior.
[0003] Newer flywheel systems dissipate too much power in the form
of heat to cool the flywheels by conduction alone.
SUMMARY OF THE INVENTION
[0004] The present invention is a cooling system 100 that brings
heat from inside a flywheel 140 to the exterior where it is
dissipated by one or more means. The cooling system 100 comprises
one or more heat pipes that transfer the heat to the exterior of
the flywheel and those heat pipes dissipated the heat to various
heat sinks.
[0005] Another aspect of the invention is a system comprising: a
first heat pipe having an evaporator and a condenser. The first
heat pipe is mounted with the evaporator inside the canister and
the condenser outside the canister. A second heat pipe has an
evaporator thermally coupled to the condenser of the first heat
pipe. The second heat pipe has a condenser. Means are provided for
dissipating heat from the condenser of the second heat pipe.
[0006] Another aspect of the invention is a system comprising: a
flywheel stored within a canister; and a heat pipe having an
evaporator and a condenser. The heat pipe is mounted with the
evaporator inside the canister and the condenser abutting a wall of
the canister.
[0007] According to another aspect of the invention, a system is
provided for cooling a canister, the system comprising first,
second and third heat pipes. The first heat pipe has an evaporator
and a condenser. The first heat pipe is mounted with its evaporator
inside the canister and its condenser outside the canister. The
second heat pipe has an evaporator thermally coupled to the
condenser of the first heat pipe. The second heat pipe has a
condenser. The third heat pipe has an evaporator thermally coupled
to the condenser of the second heat pipe. The third heat pipe has a
condenser with a heat dissipation mechanism thereon.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a side elevation view of an exemplary cooling
system according to the present invention.
[0009] FIG. 2 is a side elevation view of a flywheel energy storage
system including the cooling system of FIG. 1.
[0010] FIG. 3 is an enlarged detail of the thermocoupling device
shown in FIG. 1.
[0011] FIG. 4 is a plan view of the thermocoupling shown in FIG.
3.
[0012] FIG. 5 is a side elevation view of a second exemplary
cooling system according to the present invention.
[0013] FIG. 6 is a side elevation view of a third exemplary cooling
system according to the present invention.
[0014] FIG. 7 is a side elevation view of a fourth exemplary
cooling system according to the present invention.
DETAILED DESCRIPTION
[0015] The present invention is a system 100 for cooling a canister
130. In the exemplary embodiment, the canister 130 is the silo of a
flywheel energy storage system 200 that is partially buried or
completely buried about 60 to 240 centimeters below the surface 160
of the ground. Canister 130 is a vacuum housing. Canister 130 has
an energy storage flywheel having a motor housing 140 mounted
inside the canister. It is contemplated that system 100 may be used
for cooling other types of canisters that have internal heat
sources. It is also contemplated that system 100 may be used for
cooling canisters that are located above the surface 160 of the
ground.
[0016] The system 100 includes a first heat pipe 10, a second heat
pipe 20 and a third heat pipe 30. The first heat pipe 10 has an
evaporator 12 and a condenser 14. The first heat pipe 10 is mounted
with its evaporator 12 inside the canister 200 and its condenser 14
outside the canister. The first heat pipe 10 is mounted to the
motor housing 140 within the canister 130. In the exemplary system
100, the first heat pipe 10 is positioned entirely below the ground
surface 160, but it is contemplated that the first heat pipe 10
could be positioned partially above the ground surface 160, or
entirely above the ground surface.
[0017] The second heat pipe 20 has an evaporator 22 conductively
coupled to the condenser 14 of the first heat pipe 10. The second
heat pipe 20 has a condenser 24. The exemplary second heat pipe 20
is a thermosyphon. A thermosyphon is a heat pipe that uses gravity
to return fluid from the condenser 24 to the evaporator 22 thereof.
The exemplary second heat pipe 20 is partially buried below the
ground surface 160, and partly above the ground surface. It is
contemplated that the second heat pipe 20 could be positioned
entirely below the ground surface 160, or entirely above the ground
surface.
[0018] The third heat pipe 30 has an evaporator 32 conductively
coupled to the condenser 24 of the second heat pipe 20. The third
heat pipe 30 has a condenser 34 with a plurality of fins 36
thereon. The exemplary fins 36 are thirty-four circular aluminum
plate fins arranged in a fin stack 38. Fins having other shapes
and/or number of fins are contemplated. The exemplary third heat
pipe 30 is completely above the ground surface 160, but it is
contemplated that the evaporator 32 of heat pipe 30 could be
located at or below ground level. The evaporator 32 of the
exemplary third heat pipe 30 is oriented substantially vertically,
and the condenser 34 of the third heat pipe is at a substantial
angle (90-.alpha.) away from vertical. The angle .alpha. of the
condenser 34 of the third heat pipe 30 is at least about 5 degrees
from horizontal. As an alternative to fins 36, an extruded heat
sink (not shown) may be mounted on the condenser 34 of the third
heat pipe 30.
[0019] The heat may be rejected by finstack 38 to the atmosphere by
natural convection. Alternatively, forced convection may be used.
An exemplary system transports 60 Watts of power from the flywheel
system, with a temperature difference of about 10-12 degrees
Centigrade between the canister 130 and the ambient temperature.
Other power levels and/or temperature differences are also
contemplated.
[0020] In the exemplary embodiment, all three of the heat pipes 10,
20 and 30 have wicks formed of sintered metal, such as copper, for
example. In heat pipe 10, the wick 13 only is present in the
evaporator section 12. The wick does not extend beyond the
evaporator 12 into the condenser 14. FIG. 1 only shows the wick 13
of heat pipe 10, but the wicks of heat pipes 20 and 30 may be
configured similarly. The wick 13 may have a cross section in the
shape of an I-beam, or other wick shapes may be used. Because heat
pipe 10 is vertical, heat pipe 20 rises continuously without any
local maximum, and the condenser 34 of heat pipe 30 is at least 5
degrees from the horizontal, gravity returns the condensed fluid to
the evaporators 12, 22, 32 without the need for wicks in the
condensers 14, 24, 34.
[0021] In the exemplary embodiment, all three of the heat pipes use
methanol as the working fluid. Other known working fluids may be
used.
[0022] As shown in FIG. 2, the first heat pipe 10 is mounted within
a block 150 of metal having a hole therethrough to receive the heat
pipe. The block 150 is mounted to the flywheel system 140. For
example, the block 150 may have a cylindrical bore 151 sized to
receive the heat pipe 10. The block 150 can be cut in half, along a
plane passing through the center of the bore 151, to easily mount
the heat pipe 10 within the bore. A conventional thermal interface
material (e.g., thermal grease, or thermally conductive adhesive)
may be placed on the inner surface of the bore 151 to ensure good
conduction between block 150 and heat pipe 10 throughout the
surface of the bore 151. The two halves of the block 150 may be
fastened together by conventional fastening means.
[0023] FIG. 2 shows a seal 40 where the first heat pipe 10 passes
through the dome 120 of canister 130. In the exemplary embodiment,
the seal is a "CONFLAT.RTM." style flange, such as those
manufactured by Varian, Inc. of Palo Alto, Calif. This type of
flange provides a reliable, all-metal, leak-free seal over a wide
range of temperatures. Alternatively, similar flanges made by other
manufacturers, or other types of seals known to those of ordinary
skill may be used.
[0024] System 100 includes two thermocoupling devices 50 and 60.
FIGS. 3 and 4 show the couplings 50, 60 in detail. In the exemplary
embodiment, each coupling 50, 60 comprises a metal block (e.g.,
copper or aluminum) having a pair of cylindrical bores
therethrough. The first bore of thermocoupling 50 receives the
condenser 14 of heat pipe 10, and the second bore of thermocoupling
50 receives the evaporator 22 of heat pipe 20. The block 50 is
split into two pieces 50a, 50b, with one of the bores split in half
across the two pieces. A thermal interface material (e.g., solder,
thermal grease or thermally conductive adhesive is applied to
provide good conduction between the heat pipe 10 and the
thermocoupling 50. In the exemplary embodiment, the second heat
pipe 20 is soldered into thermocoupling 50. Clamping fasteners
(e.g., screws) 52 hold the two portions 50a, 50b of coupling 50
together. Alternatively, the block 50 may be split along a plane of
symmetry into two halves, so that each bore is divided in half.
[0025] Similarly, the first bore of thermocoupling 60 receives the
condenser 24 of heat pipe 20, and the second bore of thermocoupling
60 receives the evaporator 32 of heat pipe 30. The block 60 is
split in two portions, with one (or each) bore divided in half. A
thermal interface material (e.g., thermal grease or thermally
conductive adhesive is applied to provide good conduction between
the heat pipe 20 and the thermocoupling 60. Heat pipe 30 is
soldered to the bore of thermocoupling 60. Clamping fasteners 62
hold the two portions of coupling 60 together. The coupling 60 may
be split as shown in FIGS. 3 and 4, or split along the axis of
symmetry through both bores.
[0026] Although the exemplary thermocouplings 50, 60 are
cylindrical, thermocouplings 50 and 60 may have other shapes, such
as a parallelepiped (block) shape.
[0027] Thermocouplings 50, 60 have a sufficient length to achieve a
desired temperature difference (.DELTA.T). For example, experiments
have indicated that a .DELTA.T of about 3.25 degrees centigrade is
achieved between the condenser of heat pipe 10 and the evaporator
of heat pipe 20 using a thermocoupling 50 about 10 centimeters
long. Thus, the .DELTA.T from the two thermocouplings 50, 60
combined accounted for about 50% of the total .DELTA.T between the
motor housing 140 and the ambient. Other thermocoupling lengths are
contemplated, ranging from about 5 centimeters to about 20
centimeters.
[0028] In the exemplary embodiment, the second heat pipe 20 passes
through a cabinet 70, which may be a flywheel electronics module
(FEM) cabinet. The cabinet 70 can provide support for the second
heat pipe 20, if heat pipe 20 extends a long distance above the
ground. Alternative support structures for heat pipe 20 are also
contemplated.
[0029] The heat pipe system 100 operates passively, eliminating
maintenance and reliability concerns. This makes the exemplary
system 100 advantageous for use in areas that are remote from
maintenance workers.
[0030] Although the exemplary heat pipe system has three heat pipes
a similar design may include only a single heat pipe. The
evaporator of the single heat pipe would penetrate the canister
below ground and a condenser with a fin stack or extrusion would be
positioned above ground.
[0031] It is also contemplated that systems may be constructed with
any number of two or more heat pipes. For example, there may be a
single thermocoupling, which may be positioned above or below
ground. Alternatively, additional heat pipes and thermocouplings
may be interposed between the first and second (or second and
third) heat pipes. For example, an additional thermocoupling and
fourth heat pipe may be used to thermally couple the second and
third heat pipes. Thus, configurations including four, five or more
heat pipes are also contemplated.
[0032] Although the exemplary embodiment includes a finstack,
further variations of the exemplary embodiment are contemplated.
These may include, for example, use of heat pipes to bring the heat
inside the flywheel to the exterior of the canister, to be
dissipated by interfacing to one or more heat dissipating means.
The heat dissipating means may include heat sinks such as the
ambient air, a pumped water loop, the surrounding ground, a phase
change energy storage material, or the like.
[0033] For example, the various heat sinks could be ambient air,
the ground 160 (if the canister 200 is buried) or some other
cooling medium such as pumped water-cooling or energy storage
medium for example. Either way, the heat pipe(s) are the conduit to
transfer the heat to the heat sink. After the heat is transferred
to the exterior to the canister 200, the selection of the
appropriate cooling method is dependent upon many parameters such
as geographical location, surrounding temperatures, availability of
water, and whether the canister 200 is above or below ground. When
below ground, one exterior cooling approach uses heat pipes in a
spider like array leading away from the canister 200 which
dissipates the heat to surrounding soil/aggregate. Separate heat
storage mediums can be substituted without changing the cooling
system. These heat storage mediums can be below ground or above
ground. When the heat is brought to the surface for dissipation,
one or more heat pipes can be used as described above.
[0034] FIG. 5 shows a second exemplary system 500. The system has
two heat pipes 10 and 30. Heat pipe 10 has its evaporator inside
the canister 200, and its condenser outside of the cabinet. Heat
pipe 30 has a condenser with a heat dissipation means, such as a
fin stack. There is a single thermocoupling 60 connecting heat
pipes 10 and 30. Thermocoupling 60 may be below or above ground.
Other items in system 500 are the same as system 100, and a
description thereof is not repeated.
[0035] FIG. 6 shows a third exemplary system 600. The system has
one heat pipe 10. Heat pipe 10 has its evaporator inside the
canister 200, and its condenser outside of the cabinet. Heat pipe
10 has a condenser with a heat dissipation means, such as a fin
stack. Other items in system 600 are the same as system 100, and a
description thereof is not repeated.
[0036] FIG. 7 shows a fourth exemplary system 700. In system 700,
one or more heat pipes 730 transfer heat from the flywheel 740 to a
wall 710 of the canister. The canister wall 710 spreads the heat
and conducts heat to the surroundings (which may be ground, air, or
both). Preferably, the heat pipe 730 abuts the inside wall 710 of
the canister, as shown in FIG. 7. Alternatively, the heat pipe 730
may penetrate the wall 710 or dome 720 of the canister and abut the
outside of the wall or dome (not shown). To increase the heat
transfer capacity, additional heat pipes 730 may be added to
maintain a desired flywheel temperature. Alternatively, the
dimension of the heat pipes 730 may be increased to provide more
heat transfer. Because heat pipes 730 are relatively short, it is
not necessary to use thermosyphon return of fluid to the
evaporator. Thus, heat pipes 730 may be of any configuration, and
may include wicks to transport liquid from the condenser to the
evaporator. One or more heat sinks 736 may be mounted to the
exterior of canister wall 710 to enhance dissipation of heat from
the canister 710. The heat sink 736 may be of any design, including
folded fins or any other extended heat transfer surface.
[0037] Although the invention has been described in terms of
exemplary embodiments, it is not limited thereto. Rather, the
appended claim should be construed broadly, to include other
variants and embodiments of the invention, which may be made by
those skilled in the art without departing from the scope and range
of equivalents of the invention.
* * * * *