U.S. patent application number 12/631363 was filed with the patent office on 2011-06-09 for systems relating to geothermal energy and the operation of gas turbine engines.
This patent application is currently assigned to General Electric Company. Invention is credited to David W. Ball, JR., Douglas S. Byrd, Rahul J. Chillar, Hua Zhang.
Application Number | 20110132571 12/631363 |
Document ID | / |
Family ID | 43972665 |
Filed Date | 2011-06-09 |
United States Patent
Application |
20110132571 |
Kind Code |
A1 |
Zhang; Hua ; et al. |
June 9, 2011 |
SYSTEMS RELATING TO GEOTHERMAL ENERGY AND THE OPERATION OF GAS
TURBINE ENGINES
Abstract
A geothermal heat exchange system for use in a gas turbine power
plant that includes an inlet plenum that directs a flow of air to a
compressor that compresses a flow of air that is then mixed with a
fuel and combusted in a combustor such that the resulting flow of
hot gas is directed through a turbine, the geothermal heat exchange
system comprising means for exchanging heat between a ground and
the flow of air moving through the inlet plenum.
Inventors: |
Zhang; Hua; (Greer, SC)
; Byrd; Douglas S.; (Greer, SC) ; Ball, JR.; David
W.; (Easley, SC) ; Chillar; Rahul J.;
(Marietta, GA) |
Assignee: |
General Electric Company
|
Family ID: |
43972665 |
Appl. No.: |
12/631363 |
Filed: |
December 4, 2009 |
Current U.S.
Class: |
165/45 |
Current CPC
Class: |
F02C 1/04 20130101; Y02E
10/10 20130101; F24T 10/40 20180501; F24T 10/10 20180501; F05B
2260/208 20130101 |
Class at
Publication: |
165/45 |
International
Class: |
F24J 3/08 20060101
F24J003/08 |
Claims
1. A geothermal heat exchange system for use in a gas turbine power
plant that includes an inlet plenum that directs a flow of air to a
compressor that compresses a flow of air that is then mixed with a
fuel and combusted in a combustor such that the resulting flow of
hot gas is directed through a turbine, the geothermal heat exchange
system comprising means for exchanging heat between a ground and
the flow of air moving through the inlet plenum.
2. The geothermal heat exchange system according to claim 1,
wherein the means for exchanging heat between the ground and the
flow of air moving through the inlet plenum comprises a heat
pipe.
3. The geothermal heat exchange system according to claim 1,
wherein the means for exchanging heat between the ground and the
flow of air moving through the inlet plenum comprises a heat
sink.
4. The geothermal heat exchange system according to claim 1,
wherein the means for exchanging heat between the ground and the
flow of air moving through the inlet plenum comprises a heat
transfer fluid circulated via a pump through a circuit that passes
through the ground and the inlet plenum.
5. The geothermal heat exchange system according to claim 1,
wherein the means for exchanging heat between the ground and the
flow of air moving through the inlet plenum comprises a
thermosiphon.
6. The geothermal heat exchange system according to claim 1,
wherein the ground comprises one of a position in the ground below
the surface of the earth and a position beneath the surface of a
body of water.
7. The geothermal heat exchange system according to claim 1,
wherein the ground comprises a position in the ground at a
predetermine depth below the surface of the earth.
8. The geothermal heat exchange system according to claim 1,
wherein the predetermined depth comprises a depth of greater than
25 feet.
9. The geothermal heat exchange system according to claim 1,
wherein the predetermined depth comprises a depth between 10 and 50
feet.
10. The geothermal heat exchange system according to claim 2,
wherein the heat pipe comprises a two-phase heat transfer device
that includes a sealed tube made of a material with high thermal
conductivity both a hot end and a cold end; and wherein the sealed
tube is evacuated and backfilled with a small quantity of a working
fluid.
11. The geothermal heat exchange system according to claim 10,
wherein working fluid comprises one of water, acetone, nitrogen,
methanol, ammonia, and sodium.
12. The geothermal heat exchange system according to claim 10,
wherein the heat pipe is substantially vertically aligned and
comprises a wick structure, the wick structure comprising a
material that is configured to provide a desired capillary pressure
on the condensed working fluid.
13. The geothermal heat exchange system according to claim 10,
wherein the wick structure comprises one of a groove wick
structure, a wire mesh wick structure, a powder metal wick
structure, and a fiber/spring wick structure.
14. The geothermal heat exchange system according to claim 10,
wherein the heat pipe is configured to transfer heat from the
ground to the flow of air through the inlet plenum on cold days so
that undesired ice formation is avoided.
15. The geothermal heat exchange system according to claim 10,
wherein the heat pipe is configured to transfer heat from the flow
of air through the inlet plenum to the ground on hot days so that
the efficiency of the gas turbine power plant is increased.
16. The geothermal heat exchange system according to claim 10,
wherein the heat pipes comprise a plurality of branches in the
ground.
17. The geothermal heat exchange system according to claim 10,
wherein a plurality of heat pipes are vertically aligned and
substantially evenly distributed across the inlet plenum.
18. The geothermal heat exchange system according to claim 10,
further comprising means for transferring'heat between a flow of
exhaust from the turbine to the inlet plenum; wherein the means for
transferring heat between the flow of exhaust from the turbine to
the inlet plenum comprises a heat pipe.
19. A geothermal heat exchange system for use in a gas turbine
power plant that includes an inlet plenum that directs a flow of
air to a compressor that compresses a flow of air that is then
mixed with a fuel and combusted in a combustor such that the
resulting flow of hot gas is directed through a turbine, the
geothermal heat exchange system comprising a plurality of heat
pipes that are configured to exchange heat between a location
within a ground at a predetermined depth and the flow of air moving
through the inlet plenum; wherein the heat pipe comprises a
two-phase heat transfer device that includes a sealed tube made of
a material with high thermal conductivity both a hot end and a cold
end; and wherein the sealed tube is evacuated and backfilled with a
small quantity of a working fluid.
20. The geothermal heat exchange system according to claim 10,
wherein the heat pipe is substantially vertically aligned, extended
from the location within the ground to a position within the inlet
plenum; and wherein the heat pipe includes a wick structure, the
wick structure comprising a material that is configured to provide
a desired capillary pressure on the condensed working fluid such
that, in use, the heat pipe transfers heat from the flow of air
through the inlet plenum to the ground on hot days so that the
efficiency of the gas turbine power plant is increased.
Description
BACKGROUND OF THE INVENTION
[0001] This present application relates generally to gas turbine
engines and apparatus, systems and methods related thereto. More
specifically, but not by way of limitation, the present application
relates to apparatus, systems and methods for enhancing gas turbine
energy performance by use of, among other things, geothermal
energy.
[0002] With rising energy cost and increasing demand, the objective
of improving the efficiency of gas turbine engines and more
effectively exploiting renewable energy sources, such as geothermal
energy, is a significant one. Toward this aim, as described below,
cost-effective systems may be developed to use the relatively
constant temperature found beneath the surface of the earth to
improve gas turbine engine operation, particularly as it relates to
hot and cold day operation.
[0003] As one of ordinary skill in the art will appreciate, the
performance of gas turbine engines may be negatively affected when
ambient temperatures are either too hot or too cold. For example,
when the inlet air temperature is too hot, the gas turbine heat
rate increases and output power deceases, which, of course,
decreases the efficiency of the engine. On the other hand, when
ambient temperatures fall below a certain level, icing may occur.
This may occur at the inlet to the compressor, for example, on the
inlet to the filter house, or the inlet guide vanes or other
similarly situated components. The icing may damage equipment or
cause it to operate ineffectively. For example, icing may prevent
the IGV from operating correctly, which may negatively impact the
efficiency of the turbine engine.
[0004] Convention systems have been proposed for resolving these
issues. For example, for hot day operation, some conventional
systems propose the use of a mechanical chiller system to cool the
air entering the compressor. This option is undesirable because the
energy required to operate the chiller significantly impacts the
overall efficiency of the gas turbine engine as well as the high
equipment cost associated with the chiller. Another conventional
system is an inlet fogging system, which includes injecting water
vapor into the air entering the compressor. The evaporation of the
injected vapor decreases the temperature of the air flow. However,
the proper function of this type of system is still at least
somewhat dependent on ambient conditions and requires the
installation of costly hardware and control systems. Further, the
addition of water to the engine flow path in this manner may cause
more rapid degradation and erosion of parts within the flow path
and, as such, generally increases maintenance costs.
[0005] For cold day operation, conventional systems generally
include drawing energy from the engine exhaust to raise the
temperature of the air entering the compressor. Again, though, such
systems require an installation of costly hardware and control
systems. Further, to the extent that the energy in the exhaust may
be used for other purposes, such as, for example, as the heat
source in the steam turbine of a combined cycle plant, the
diverting of a portion of the exhaust energy generally decreases
the overall efficiency of the power plant.
[0006] As a result, there remains a need for improved apparatus,
systems and methods for cost-effectively alleviating performance
issues in gas turbine engines that occur during hot and cold day
operation.
BRIEF DESCRIPTION OF THE INVENTION
[0007] The present application thus describes a geothermal heat
exchange system for use in a gas turbine power plant that includes
an inlet plenum that directs a flow of air to a compressor that
compresses a flow of air that is then mixed with a fuel and
combusted in a combustor such that the resulting flow of hot gas is
directed through a turbine, the geothermal heat exchange system
comprising means for exchanging heat between a ground and the flow
of air moving through the inlet plenum.
[0008] The present application further describes a geothermal heat
exchange system for use in a gas turbine power plant that includes
an inlet plenum that directs a flow of air to a compressor that
compresses a flow of air that is then mixed with a fuel and
combusted in a combustor such that the resulting flow of hot gas is
directed through a turbine, the geothermal heat exchange system
comprising a plurality of heat pipes that are configured to
exchange heat between a location within a ground at a predetermined
depth and the flow of air moving through the inlet plenum; wherein
the heat pipe comprises a two-phase heat transfer device that
includes a sealed tube made of a material with high thermal
conductivity both a hot end and a cold end; and the sealed tube is
evacuated and backfilled with a small quantity of a working
fluid.
[0009] These and other features of the present application will
become apparent upon review of the following detailed, description
of the preferred embodiments when taken in conjunction with the
drawings and the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a section view of a gas turbine engine typical of
the types of turbine engines that may be used in power plants in
which embodiments of the present invention may be used;
[0011] FIG. 2 illustrates a schematic plan of a gas turbine engine,
the representation of which will be used to illustrate power plants
according to embodiments of the present invention;
[0012] FIG. 3 is a schematic plan illustrating the configuration of
a gas turbine power plant according to an exemplary embodiment of
the present application;
[0013] FIG. 4 is a schematic plan illustrating a front view (i.e.,
into the mouth of the inlet plenum) of the configuration of heat
pipes in the inlet plenum according to an exemplary embodiment of
the present application; and
[0014] FIG. 5 is a schematic plan illustrating the configuration of
a gas turbine power plant according to an alternative embodiment of
the present application.
DETAILED DESCRIPTION OF THE INVENTION
[0015] Illustrative embodiments of the invention now will be
described more fully hereinafter with reference to the accompanying
drawings, in which some, but not all embodiments of the invention
are shown. Indeed, the invention may be embodied in many different
forms and should not be construed as limited to the embodiments set
forth herein; rather, these embodiments are provided so that this
disclosure will satisfy applicable legal requirements. Like numbers
refer to like elements throughout.
[0016] To describe clearly the invention of the current
application, it may be necessary to select terminology that refers
to and describes certain machine components or parts of a turbine
engine. Whenever possible, common industry terminology will be used
and employed in a manner consistent with its accepted meaning.
However, it is meant that any such terminology be given a broad
meaning and not narrowly construed such that the meaning intended
herein and the scope of the appended claims is unreasonably
restricted. Those of ordinary skill in the art will appreciate that
often certain components may be referred to with several different
names. In addition, what may be described herein as a single part
may include and be referenced in another context as consisting of
several component parts, or, what may be described herein as
including multiple component parts may be fashioned into and, in
some cases, referred to as a single part. As such, in understanding
the scope of the invention described herein, attention should not
only be paid to the terminology and description provided, but also
to the structure, configuration, function, and/or usage of the
component as provided herein.
[0017] In addition, several descriptive terms may be used herein.
The meaning for these terms shall include the following
definitions. As used herein, "downstream" and "upstream" are terms
that indicate a direction relative to a flow of working fluid
through the turbine. As such, the term "downstream" means the
direction of the flow, and the term "upstream" means in the
opposite direction of the flow through the turbine engine. Related
to these terms, the terms "aft" and/or "trailing edge" refer to the
downstream direction, the downstream end and/or in the direction of
the downstream end of the component being described. And, the terms
"forward" or "leading edge" refer to the upstream direction, the
upstream end and/or in the direction of the upstream end of the
component being described. The term "radial" refers to movement or
position perpendicular to an axis. It is often required to describe
parts that are at differing radial positions with regard to an
axis. In this case, if a first component resides closer to the axis
than a second component, it may be stated herein that the first
component is "inboard" or "radially inward" of the second
component. If, on the other hand, the first component resides
further from the axis than the second component, it may be stated
herein that the first component is "outboard" or "radially outward"
of the second component. The term "axial" refers to movement or
position parallel to an axis. And, the term "circumferential"
refers to movement or position around an axis.
[0018] Referring now to the figures, FIG. 1 is an illustration of a
convention gas turbine engine 50. In general, gas turbine engines
operate by extracting energy from a pressurized flow of hot gas
that is produced by the combustion of a fuel in a stream of
compressed air. As illustrated in FIG. 1, gas turbine engine 50 may
be configured with an axial compressor 52 that is generally
mechanically coupled by a common shaft or rotor to a downstream
turbine section or turbine 54, and a combustor 56 positioned
between the compressor 52 and the turbine 54.
[0019] The compressor 52 may include a plurality of stages, with
each stage having a row of compressor rotor blades followed by a
row of compressor stator blades. Particularly, a stage generally
includes a row of compressor rotor blades, which rotate about a
central shaft, followed by a row of compressor stator blades, which
remain stationary during operation. The compressor stator blades
generally are circumferentially spaced one from the other and fixed
about the axis of rotation. The compressor rotor blades are
attached to the shaft such that, when the shaft rotates during
operation, the compressor rotor blades rotate about it. As one of
ordinary skill in the art will appreciate, the compressor rotor
blades are configured such that, when spun about the shaft, they
impart kinetic energy to the air or fluid flowing through the
compressor 52. The turbine 54 also may include a plurality of
stages. A turbine stage may include a plurality of turbine buckets
or turbine rotor blades, which rotate about the shaft during
operation, and a plurality of nozzles or turbine stator blades,
which remain stationary during operation. The turbine stator blades
generally are circumferentially spaced one from the other and fixed
about the axis of rotation. Whereas, the turbine rotor blades may
be mounted on a turbine wheel for rotation about the shaft.
[0020] In use, the rotation of compressor rotor blades 60 within
the axial compressor 52 compresses a flow of air. In the combustor
56, energy is released when the compressed air is mixed with a fuel
and ignited. The resulting flow of pressurized hot gases from the
combustor 56, which generally is referred to as the working fluid
of the engine, is then expanded through the turbine rotor blades.
The flow of working fluid induces the rotation of the turbine rotor
blades about the shaft. Thereby, the energy of the fuel is
transformed into the kinetic energy of the flow of working fluid,
which is then transformed into the mechanical energy of the
rotating blades and, via the connection between the rotor blades
and the shaft, the rotating shaft. The mechanical energy of the
shaft may then be used to drive the rotation of the compressor
rotor blades, such that the necessary supply of compressed air is
produced, and also, for example, to drive a generator (not shown)
to produce electricity.
[0021] FIG. 2 illustrates a schematic plan of a gas turbine engine
100, the representation of which will be used to illustrate power
plants according to embodiments of the present invention. As shown,
the gas turbine engine 100 may include a compressor 52, a combustor
56, and a turbine 54. At the upstream end of the compressor 52, an
inlet plenum 112 may be located. The inlet plenum 112 essentially
provides a channel through which a supply of air is directed into
the compressor 52. It will be appreciated that the configuration of
the inlet plenum 112 may comprise many different configurations. As
illustrated, the inlet plenum may be configured to have a
relatively wide mouth that decreases in cross-sectional area into a
channel that directs a supply of air to the inlet of the compressor
52. Of course, in some gas turbine engine applications, a
significantly smaller structure may be used to provide an inlet for
the air entering the compressor 52. As such, as used herein, inlet
plenum 112 is meant to describe any structure, large or small, that
is positioned upstream of one of the stages of the compressor 52
through which at least a portion of the air entering the compressor
52 passes. As one of ordinary skill in the art will appreciate, the
inlet plenum 112 may include certain components, such as filters,
silencers, etc., that improve the function of it. However, because
these components are not essential or preclusive to the function of
a power plant according to the present invention, they have been
omitted from the figures. As will be seen, the flexibility of
embodiments of the present invention allows that it may be
incorporated in a variety of ways into substantially any type of
inlet plenum 112 structure or directly into the compressor 52
itself.
[0022] FIG. 3 is a schematic plan illustrating the configuration of
a gas turbine power plant 130 according to an embodiment of the
present application. Similar to the system shown in FIG. 2, the gas
turbine power plant 130 may include a compressor 52, a combustor
56, a turbine 54, and an inlet plenum 112. According to the present
invention, the gas turbine power plant 130 also may include a heat
exchange device that provides for the exchange of energy between
the flow of air in the inlet plenum 112 or through the compressor
52 and the earth or ground 134. As used herein, "ground" is meant
to include any type of geothermal medium. In some embodiments,
ground refers to the earth at a predetermined level underground, as
shown in FIG. 3. As will be appreciated, the temperature of the
ground beneath the surface of the earth remains fairly constant
regardless of the season. This is particularly true at depths
between approximately 25 and 500 feet beneath the surface of the
ground. In some embodiments, shallower depths also may be used; for
example, depths between approximately 10 and 50 feet beneath the
surface of the ground may be appropriate for certain
applications.
[0023] These relatively constant subsurface temperatures mean that
the ground temperature within these given depth ranges remains
relatively cool year round even in warm climate locations. For
example, the ground temperature of Atlanta, Ga. remains a fairly
constant 62.degree. F. throughout the year. At the other end of the
spectrum, in relatively cold climate locations, the ground
temperature remains relatively warm even in the coldest months of
the year. For example, the ground temperature of New York, N.Y.
remains a fairly constant 52.degree. F. throughout the year. As
stated, "ground" also may refer to other types of geothermal
mediums, such as a subsurface location in a body of water, such as
a lake or a river or the ocean.
[0024] As shown in FIG. 3, in one preferred embodiment, the heat
exchange device may be one or more elongated heat transfer
structures 136, such as one or more pipes, that extend from a
position within the ground (which, for example, may be a position
in the ground below the earth's surface, a subsurface location in a
lake, or other such position) to a position within the inlet plenum
112. The heat transfer structures 136 may be configured to
efficiently transfer heat from a hot side (which, depending on the
application as well as current ambient and ground temperature
conditions, may be either the ground or the inlet plenum) to a cold
side (which, depending on the application as well as current
ambient and ground temperature conditions, may be either the ground
or the inlet plenum). At the hot side and the cold side, the
structure 136 generally will include an outer surface that conducts
heat well, such as a metallic surface. In addition, one end of the
structure 136, which, as shown may be a pipe, may be placed within
the ground at a desired depth such that it contacts the surrounding
earthen material or water and heat transfer between the surrounding
material and the structure 136 is as desired. The other end of the
structure or pipe 136 may be placed in the inlet plenum 112 such
that the air flowing through the inlet plenum 112 flows over and
around it so heat transfer occurring between the structure 136 and
the air flow occurs at a desired rate.
[0025] In some embodiments, the elongated structure 136 of FIG. 3
may comprise a conventional heat pipe. A heat pipe is a two-phase
heat transfer device with a high effective thermal conductivity. A
heat pipe generally consists of a sealed pipe or tube made of a
material with high thermal conductivity such as steel, copper or
aluminum at both hot and cold ends. It can be cylindrical or
planar, and, as discussed below, the inner surface may be lined
with a capillary wicking material. In construction, the heat pipe
is evacuated and backfilled with a small quantity of a working
fluid such as water, acetone, nitrogen, methanol, ammonia, or
sodium. Other types of inorganic materials also may be used. Heat
is absorbed in the evaporator region by vaporizing the working
fluid. The vapor transports heat to the condenser region where the
vapor condenses, releasing heat to a cooling medium.
[0026] In some embodiments, the heat pipe of the current invention
may be a looped heat pipe, i.e., a heat pipe with a wick structure
that exerts capillary pressure on the liquid phase of the working
fluid. The wick structure may include any material capable of
exerting sufficient capillary pressure on the condensed liquid to
wick it back to the heated end. In some embodiments, the wick
structure may be one of the common wick structures used in
conventional heat pipe applications, which include a groove wick
structure (i.e., a series of grooves the run lengthwise along the
inner surface of the heat pipe), a wire mesh wick structure, a
powder metal wick structure, and a fiber/spring wick structure. The
heat pipe may not need a wick structure if gravity or some other
source of acceleration is sufficient to overcome surface tension
and cause the condensed liquid to flow back to the heated end.
[0027] As shown in FIG. 3, in some embodiments, the heat pipes 136
of the present invention may be aligned vertically. In this
arrangement and in the absence of a wicking structure, geothermal
energy from the ground 134 may be used to heat the flow of air into
the compressor 52 (i.e., the warmer ground end of the heat pipe 136
evaporates a working fluid that condenses at the cold end of the
heat pipe in the inlet plenum 132 thereby heating the air flowing
around it). This arrangement may be used when the ground
temperature exceeds the air temperature, which may be effective
during cold day operation in preventing ice formation on engine
components.
[0028] According to an alternative embodiment of the present
application, a wick structure, as described above, may be employed
so that the vertically aligned heat pipes of FIG. 3 still may be
used when the ground temperature is less than ambient air
temperature. In this case, engine operators may desire to cool the
ambient air being supplied to the compressor. Instead of gravity
returning the condensed fluid to the cold side of the heat pipe,
the capillary pressure provided by the wick structure overcomes
gravity, wicking the condensed fluid upward from the colder ground
side to the warmer side inside the plenum. Once inside the plenum,
the heat pipe absorbs heat from the passing air flow via the
evaporation of the wicked fluid. Cooling the air in this manner, as
discussed, generally increases the efficiency of the gas turbine
power plant and may be used when the ambient temperature is high to
improve engine performance.
[0029] The advantages of using heat pipes for any necessary cooling
or heating several. First, heat pipes are completely passive heat
transfer systems, having no moving parts to wear out. Second, heat
pipes require no energy to operate. Third, heat pipes are
relatively inexpensive. Fourth, heat pipes are flexible in size,
shape and effective operating temperature ranges.
[0030] In operation, when ambient temperatures go below a desirable
level, heat pipes having the configuration shown in FIG. 3 may be
activated to pump heat from underground to heat the air passing
through the inlet plenum 112. This, for example, may be used to
prevent unwanted ice from forming on the inlet filter house or
inlet guide vanes. On the other hand, when ambient temperatures go
above a desirable level, heat pipes having the configuration shown
in FIG. 3 may be activated to pump heat from the air passing
through the inlet plenum 112 into the ground. This, for example,
may be used on hot days to increase the efficiency of the
engine.
[0031] As shown in FIGS. 3 and 4, in some embodiments, the heat
pipes may have a plurality of branches. The branches 138 generally
increase the surface area for heat exchange with the earth.
[0032] FIG. 4 illustrates a front view of the inlet plenum 112
(i.e., into the mouth of the inlet plenum 112) and demonstrates an
exemplary configuration of heat transfer structure 136 (in this
case, heat pipes) within the inlet plenum according to an
embodiment of the present application. As shown, the heat pipes may
be arranged vertically and extend from the interior of the inlet
plenum 112 to a desired depth within the ground 134. A plurality of
heat pipes may be evenly distributed across the inlet plenum 112.
In certain applications, more or less heat pipes may be used.
[0033] Referring now to FIG. 5, an alternative embodiment of a gas
turbine power plant according to the present application is shown,
a gas turbine power plant 150. In this case, a secondary heat
transfer structure 152 is configured to exchange heat between the
inlet plenum 112 and the exhaust of the turbine 54. A heat recovery
steam generator 154 may be present in this type of power plant, as
shown. A portion of the turbine exhaust may be diverted from the
main flow via an exhaust by pass 155 and directed through a heat
transfer unit 156. Within the heat transfer unit 156, the exhaust
may heat the secondary heat transfer structure 152. The secondary
heat transfer structure 152, as shown, may connect to the heat
transfer structure 136, where the heat from the exhaust may be
pumped into the inlet plenum 112. This configuration provides an
additional heating element to the power plant, which, as one of
ordinary skill in the art will appreciate, may be necessary for
certain applications. The secondary heat transfer structure 152 may
comprise heat pipes consistent with the description above.
[0034] As stated, in preferred embodiments, the heat transfer
structure 136 and the secondary heat transfer structure 152
comprise heat pipes. In other embodiments according to the present
invention, the heat transfer structure 136 and the secondary heat
transfer structure 152 may comprise other conventional heat
transfer structures or systems. For example, a heat sink made from
solid pipes of conductive metals may be used in place of the heat
pipes. While the two-phase heat transfer associated with heat pipes
may be more efficient mode of heat transfer, the single phase
conductive heat transfer associated with certain solid materials
may be sufficient for some applications. In other embodiments, a
heat transfer fluid may be circulated via a pump through a circuit
so that the fluid exchange heat between the ground 134 and the
inlet plenum 112. In still other embodiments, a thermosiphon may be
used. As one of ordinary skill in the art will appreciate, a
thermosiphon is a mechanism similar to a heat pipe in which thermal
energy is transferred by fluid buoyancy rather than evaporation and
condensation.
[0035] As one of ordinary skill in the art will appreciate, the
many varying features and configurations described above in
relation to the several exemplary embodiments may be further
selectively applied to form the other possible embodiments of the
present application. For the sake of brevity and taking into
account the abilities of one of ordinary skill in the art, all of
the possible iterations is not provided or discussed in detail,
though all combinations and possible embodiments embraced by the
several claims below or otherwise are intended to be part of the
instant application. In addition, from the above description of
several exemplary embodiments of the invention, those skilled in
the art will perceive improvements, changes and modifications. Such
improvements, changes and modifications within the skill of the art
are also intended to be covered by the appended claims. Further, it
should be apparent that the foregoing relates only to the described
embodiments of the present application and that numerous changes
and modifications may be made herein without departing from the
spirit and scope of the application as defined by the following
claims and the equivalents thereof.
* * * * *