U.S. patent application number 12/694381 was filed with the patent office on 2012-09-27 for dual use cooling systems.
This patent application is currently assigned to The Boeing Company. Invention is credited to Chin-Hsi Chien, Lijun Gao, Shengyi Liu.
Application Number | 20120240882 12/694381 |
Document ID | / |
Family ID | 43417098 |
Filed Date | 2012-09-27 |
United States Patent
Application |
20120240882 |
Kind Code |
A1 |
Gao; Lijun ; et al. |
September 27, 2012 |
Dual Use Cooling Systems
Abstract
Cooling systems and methods of use are disclosed. A particular
method includes routing at least a first portion of a coolant
stream from a first heat exchanger to a second heat exchanger to
receive heat from a hot side of a thermoelectric cooling device.
The method also includes cooling one or more electronic devices
using a cold side of the thermoelectric cooling device. The method
also includes routing at least a second portion of the coolant
stream to an engine.
Inventors: |
Gao; Lijun; (Renton, WA)
; Chien; Chin-Hsi; (Bellevue, WA) ; Liu;
Shengyi; (Sammamish, WA) |
Assignee: |
The Boeing Company
Chicago
IL
|
Family ID: |
43417098 |
Appl. No.: |
12/694381 |
Filed: |
January 27, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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12550131 |
Aug 28, 2009 |
|
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12694381 |
|
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Current U.S.
Class: |
123/41.55 ;
62/3.2 |
Current CPC
Class: |
B60K 11/02 20130101;
F01P 2050/24 20130101; F01P 3/20 20130101; B60K 1/00 20130101; F25B
21/02 20130101 |
Class at
Publication: |
123/41.55 ;
62/3.2 |
International
Class: |
F01P 11/00 20060101
F01P011/00; F25B 21/02 20060101 F25B021/02 |
Claims
1. A system, comprising: an engine having an engine coolant inlet
and an engine coolant outlet; a first heat exchanger having a first
heat exchanger inlet and a first heat exchanger outlet; a second
heat exchanger having a second heat exchanger inlet and a second
heat exchanger outlet; a thermoelectric cooling device in thermal
communication with the second heat exchanger; and one or more
conduits to transport coolant; wherein a first portion of a coolant
flow from the first heat exchanger outlet is routed to the second
heat exchanger inlet to receive heat output from one or more
devices in thermal communication with the thermoelectric cooling
device, and wherein a second portion of the coolant flow from the
first heat exchanger outlet is routed to the engine coolant inlet
to receive heat output by the engine.
2. The system of claim 1, further comprising a control system
coupled to the thermoelectric cooling device, wherein the control
system adjusts power input to the thermoelectric cooling device to
control a temperature of the one or more devices in thermal
communication with the thermoelectric cooling device.
3. The system of claim 1, wherein the engine includes an internal
combustion engine.
4. The system of claim 1, wherein the first heat exchanger includes
a radiator.
5. The system of claim 1, wherein a temperature of the one or more
devices in thermal communication with the thermoelectric cooling
device is less than a temperature of the first portion of the
coolant.
6. The system of claim 1, further comprising a thermoelectric
generator in thermal communication with the first heat exchanger,
wherein the thermoelectric generator generates power based on a
temperature differential between the coolant received at the first
heat exchanger inlet and a temperature of a cold side of the first
heat exchanger.
7. The system of claim 6, wherein at least a portion of power used
by the thermoelectric cooling device is generated by the
thermoelectric generator.
8. The system of claim 1, wherein the one or more devices in
thermal communication with the thermoelectric cooling device
include a power electronics module.
9. A vehicle, comprising: an engine; a thermoelectric cooling
device to cool one or more components of the vehicle; a first heat
exchanger to receive heat from a hot side of the thermoelectric
cooling device; and a second heat exchanger to remove heat from a
coolant, wherein the coolant is supplied from the second heat
exchanger to the engine and to the first heat exchanger.
10. The vehicle of claim 9, further comprising a thermoelectric
generator to generate at least a portion of power used by the
thermoelectric cooling device based on a temperature differential
at the second heat exchanger.
11. The vehicle of claim 9, further comprising a control system to
control a temperature of the one or more components by adjusting
power supplied to the thermoelectric cooling device.
12. The vehicle of claim 9, further comprising one or more electric
motors, wherein the engine generates at least a portion of power
used by the one or more electric motors to move the vehicle, and
wherein the one or more components include a power conditioning
system that conditions power supplied to the one or more electric
motors.
13. The vehicle of claim 9, wherein the thermoelectric cooling
device comprises a solid-state Peltier effect heat pump.
14. A method, comprising: routing at least a first portion of a
coolant in a cooling system from a first heat exchanger to a second
heat exchanger to receive heat from a hot side of a thermoelectric
cooling device; cooling one or more electronic devices using a cold
side of the thermoelectric cooling device; and routing at least a
second portion of the coolant in the cooling system to an
engine.
15. The method of claim 14, wherein a coolant outlet of the second
heat exchanger is coupled to a coolant inlet of the engine, and
wherein the first portion of the coolant is the same portion of the
coolant as the second portion of the coolant.
16. The method of claim 14, wherein a coolant inlet of the second
heat exchanger is coupled to the first heat exchanger and a coolant
inlet of the engine is coupled to the first heat exchanger, and
wherein the first portion of the coolant is different than the
second portion of the coolant.
17. The method of claim 14, wherein a temperature of the first
portion of the coolant is higher than an operating temperature of
the one or more electronic devices.
18. The method of claim 17, further comprising controlling a
temperature of the one or more electronic devices by controlling
power supplied to the thermoelectric cooling device.
19. The method of claim 18, further comprising generating at least
a portion of the power supplied to the thermoelectric cooling
device using a temperature gradient at the heat exchanger.
20. The method of claim 14, wherein a temperature of the first
portion of the coolant when the first portion is received at the
second heat exchanger is substantially equal to a temperature of
the second portion of the coolant when the second portion is
received at the engine.
Description
CLAIM OF PRIORITY
[0001] This application claims priority as a continuation-in-part
from U.S. patent application Ser. No. 12/550,131, filed on Aug. 28,
2009, which is incorporated herein by reference in its
entirety.
FIELD OF THE DISCLOSURE
[0002] The present disclosure is generally related to cooling
systems and methods of use.
BACKGROUND
[0003] Multiple heat sources that require temperature control may
be present in some systems. For example, some vehicles include an
engine that generates heat and electronics that generate heat.
These vehicles may include an engine cooling system to cool the
engine and an auxiliary cooling system to cool the electronics,
etc. The engine cooling system and the auxiliary cooling system may
be separate systems due at least in part to a large difference in
operating temperatures between the engine and the electronics.
SUMMARY
[0004] Cooling systems and methods of use are disclosed. A
particular system includes two or more heat sources. The first heat
source may be an engine having an engine coolant inlet and an
engine coolant outlet. The second heat source may be a power
electronics module cooled by a thermoelectric device. The system
also includes a first heat exchanger having a first heat exchanger
inlet and a first heat exchanger outlet. The system further
includes a second heat exchanger, e.g. a cold plate, having a
second heat exchanger inlet and a second heat exchanger outlet. The
thermoelectric cooling device is in thermal communication with the
second heat exchanger. In this context, the term "thermal
communication" indicates that two or more objects are coupled in a
manner that enables transfer of heat between the objects via a
mechanism other than purely radiative heat transfer. One or more
conduits transport coolant within the system. A first portion of
coolant flow from the first heat exchanger outlet is routed to the
second heat exchanger inlet to receive heat output from one or more
devices in thermal communication with the thermoelectric cooling
device. A second portion of the coolant flow from the first heat
exchanger outlet is routed to the engine coolant inlet to receive
heat output by the engine. In some configurations, the second heat
exchanger and the engine may be coupled in a series arrangement,
such that the first portion of the coolant flow passes through the
first heat exchanger and is routed to the engine as the second
portion of the coolant flow. In some configurations, the second
heat exchanger and the engine may be coupled in a parallel
arrangement. For example, coolant routed from the first heat
exchanger outlet may be divided with some of the coolant flowing to
the second heat exchanger as the first portion of the coolant flow
and some of the coolant flowing to the engine as the second coolant
flow.
[0005] In a particular embodiment, a vehicle includes an engine, a
thermoelectric cooling device to cool one or more components of the
vehicle, and a first heat exchanger to receive heat from a hot side
of the thermoelectric cooling device. The vehicle also includes a
second heat exchanger to remove heat from a coolant. The coolant is
circulated from the second heat exchanger to the engine and to the
first heat exchanger.
[0006] In another particular embodiment, a method includes routing
at least a first portion of a coolant stream from a first heat
exchanger to a second heat exchanger to receive heat from a hot
side of a thermoelectric cooling device. The method also includes
cooling one or more electronic devices using a cold side of the
thermoelectric cooling device. The method also includes routing at
least a second portion of the coolant stream to an engine.
[0007] Efficiency, size, cost, reliability, or any combination
thereof, of a vehicle may be improved by using a single cooling
system to cool two or more heat sources that have different
operating temperatures. For example, a single cooling system may be
used to cool an engine and one or more electronic components. The
electronic components may be at a significantly lower operating
temperature than the engine. Further, in a particular embodiment, a
coolant used to cool the engine is hotter than the operating
temperature of the electronic components. However, use of a
thermoelectric cooling device, such as a solid-state Peltier heat
pump, enables driving heat against a temperature gradient to enable
removal of heat from the electronic devices by the higher
temperature coolant. Additionally, the thermoelectric cooling
device enables control of the temperature of the electronic
components by controlling power supplied to the thermoelectric
cooling device. Further, a thermoelectric generator may be used to
convert some of the waste heat from the electronic components and
the engine as power that can be supplied to the thermoelectric
cooling device.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a diagram of a first embodiment of a system to
generate electric power;
[0009] FIG. 2 is a diagram of a second embodiment of a system to
generate electric power;
[0010] FIG. 3 is a diagram of a third embodiment of a system to
generate electric power;
[0011] FIG. 4-6 are views of a thermoelectric generator according
to a particular embodiment;
[0012] FIG. 7 is a flow chart of a first embodiment of a method of
generating electric power;
[0013] FIG. 8 is a flow chart of a control scheme to control
generation of electric power according to a particular
embodiment;
[0014] FIG. 9 is a diagram illustrating control of a system to
generate electric power according to a particular embodiment;
[0015] FIG. 10 is a diagram of a first embodiment of a cooling
system;
[0016] FIG. 11 is a diagram of a second embodiment of a cooling
system;
[0017] FIG. 12 is a diagram of a third embodiment of a cooling
system; and
[0018] FIG. 13 is a flow chart of a particular embodiment of a
method of using a cooling system.
DETAILED DESCRIPTION
[0019] The features, functions, and advantages that are described
can be achieved independently in various embodiments disclosed
herein or may be combined in yet other embodiments further details
of which can be shown with reference to the following description
and drawings.
[0020] Operational efficiency of a cogeneration system may be
improved by placing a thermoelectric generator between a relatively
hot exhaust stream from a fuel cell and a relatively cold intake
stream to the fuel cell. This arrangement enables the
thermoelectric generator to generate electric power based on the
relatively large temperature differential between the hot exhaust
stream and the cold intake stream without using an additional
cooling system. Additionally, this arrangement enables preheating
of the cold intake stream before it is provided to the fuel cell.
The efficiency of the thermoelectric generator may be increased due
to the high magnitude of the temperature differential between the
fuel cell exhaust stream and the fuel cell intake stream. Further,
this arrangement does not require use of additional fuel to
generate the temperature differential used by the thermoelectric
generator to produce power; rather, waste heat in the fuel cell
exhaust stream is used by the thermoelectric generator to produce
power. Additionally, the weight of the cogeneration system is
reduced with respect to other cogeneration systems since a separate
cooling system is eliminated.
[0021] In a particular embodiment, a platform using the disclosed
cogeneration system does not need an additional cooling system to
cool exhaust from the fuel cell. Further, additional power is
generated by the thermoelectric generator using what would
otherwise be waste heat from the fuel cell. Thus, part of the power
is recovered from the waste heat leading to improved efficiency of
conversion of the fuel into electric power by the cogeneration
system.
[0022] Additionally, efficiency, size, cost, reliability, or any
combination thereof, of a vehicle may be improved by using a single
cooling system to cool two or more heat sources that have different
operating temperatures. For example, a single cooling system may be
used to cool an engine and one or more electronic components. The
electronic components may be at a significantly lower operating
temperature than the engine. Further, in a particular embodiment, a
coolant used to cool the engine is hotter than the operating
temperature of the electronic components. However, use of a
thermoelectric cooling device, such as a solid-state Peltier heat
pump enables driving heat against a temperature gradient to enable
removal of heat from the electronic devices by the higher
temperature coolant. Additionally, the thermoelectric cooling
device enables control of the temperature of the electronic
components by controlling power supplied to the thermoelectric
cooling device. Further, a thermoelectric generator may be used to
convert some of the waste heat from the electronic components and
the engine as power that can be supplied to the thermoelectric
cooling device. Accordingly, separate cooling systems are not
needed to cool the engine and the electronic components, which can
reduce cost, size, weight and complexity of systems to cool the
engine and the electronic components. Additionally, reliability of
the system may be improved due to the reduced part count and
simplicity of the "dual use" cooling system as compared to using
separate cooling systems.
[0023] FIG. 1 is a diagram of a first embodiment of a system to
generate electric power, the system generally designated 100. The
system 100 includes a platform where a power generation system is
situated. For example, the platform can be a mobile platform, such
as an aircraft, a space craft, a watercraft, or a land-based
vehicle. In another example, the platform can be a stationary
platform, such as a power generation system in a utility power
plant, an industrial site, an office building, or another
substantially stationary structure. In a particular embodiment, the
power generation system of the platform 102 includes components to
generate electric power. For example the components to generate
electric power may include a fuel cell 104 having an anode 106 and
a cathode 108. The components to generate electric power may also
include one or more thermoelectric generators (TE), such as a first
TE 110 and a second TE 120.
[0024] In a particular embodiment, the first TE 110 is coupled to
the anode 106 of the fuel cell 104, and the second TE 120 is
coupled to the cathode 108 of the fuel cell 104. This arrangement
may enable hot exhaust gas 107 from the anode 106 to be routed to a
hot side 112 of the first TE 110. Likewise, hot exhaust gas 109
from the cathode 108 may be routed to a hot side 122 of the second
TE 120. Intake gases 162 (such as, fuel 170 and oxidizer 172) that
are cool by comparison to the hot exhaust gases 107, 109 may be
received at inlets (e.g., from respective fuel and oxidizer storage
systems) and routed through respective cold sides 114, 124 of the
TEs 110, 120. In this arrangement, the TEs 110, 120 may be at or
near a point of maximum temperature differential between the hot
exhaust gases 107, 109 and the intake gases 162. In an illustrative
embodiment, the fuel cell 104 is a high temperature fuel cell, such
as a solid oxide fuel cell (SOFC). With a SOFC, the hot exhaust
gases 107, 109 may have a temperature greater than 600.degree. C.
For example, the hot exhaust gases 107, 109 may have a temperature
between about 600.degree. C. and about 800.degree. C. A temperature
of the intake gases 162 may depend on, among other things, the
operating environment of the system 100. For example, when ambient
air is used as the oxidizer 172, the temperature of the ambient air
may be less than about 50.degree. C. When the power generation
system of the platform 102 is operated by or near humans, the
ambient air may typically be between about -50.degree. C. and
50.degree. C. For purposes of a particular implementation, the
intake gases 162 may be assumed to be approximately 20.degree. C.
It is understood that the temperature of the hot exhaust gases 107,
109 and the temperature of the intake gases 162 may vary widely
depending on the particular embodiment, a particular application or
use of the system 100 and specific operating conditions.
Accordingly, the temperatures described above are exemplary and not
intended to as limitations.
[0025] The system 100 may also include a first heat exchanger 130
coupled to the anode 106 and a second heat exchanger 140 coupled to
the cathode 108. In a particular embodiment, exhaust gases from the
hot sides 112, 122 of the TEs 110, 120 may be routed to respective
inlets of hot sides 132, 142 of the heat exchangers 130, 140.
Exhaust from the cold sides 114, 124 of the TEs 110, 120 may be
routed to respective inlets of cold sides 134, 144 of the heat
exchangers 130, 140. In this embodiment, the heat exchangers 130,
140 may preheat the intake gases 162 before the intake gases 162
are provided to the fuel cell 104 as preheated intake gas 180.
Preheating the intake gas 180 may enable efficient operation of the
fuel cell 104, especially when the fuel cell 104 is a high
temperature fuel cell. In a particular embodiment, the heat
exchangers 130, 140 are counter-flow heat exchangers; however, in
other embodiments the heat exchangers 130, 140 may have other
physical arrangements.
[0026] In a particular embodiment, the system 100 may be operated
to increase the operational efficiency of the fuel cell 104.
Accordingly, a controller 150 may operate a first control valve
152, a second control valve 154, or both, to control a temperature
of the preheated intake gas 180 provided to the fuel cell 104. In a
particular embodiment, the control valves 152, 154 are between a
fuel cell outlet and a heat exchanger hot-side inlet. The control
valves 152, 154 are adjustable to control an inlet temperature of
the preheated intake gas 180. For example, the controller 150 may
operate the control valves 152, 154 to allow a portion of the hot
exhaust gases 107, 109 to bypass the TEs 110, 120 in order to
increase the temperature of the preheated intake gas 180. When the
control valves 152, 154 are opened (such that at least a portion of
the hot exhaust gases 107, 109 bypass the TEs 110, 120, the
temperature of the gas provided to the respective hot sides 132,
142 of the heat exchangers 130, 140 is increased, which increases
the temperature of the preheated intake gas 180 exiting the
respective cold sides 134, 144 of the heat exchangers 130, 140.
Thus, an amount of preheating of the preheated intake gas 180 may
be controlled by the controller 150 through operation of the
control valves 152, 154. In a particular embodiment, the controller
150 operates the first control valve 152 to achieve and/or maintain
a predetermined temperature of the preheated intake gas 180. For
example, the predetermined temperature of the preheated intake gas
180 may be a temperature selected to optimize power generation by
the fuel cell 104. Thus, the TEs 110, 120 may generate power using
waste heat from the fuel cell 104. That is, in a particular
embodiment, the fuel cell 104 may be operated as though it were a
stand alone fuel cell, and the TEs 110, 120 may recover waste heat
produced by the fuel cell 104 to generate additional electric
power. In an illustrative embodiment, the predetermined temperature
of the preheated intake gas 180 may be about 600.degree. C. Thus,
power generated by the fuel cell 104 may be increased and, when
needed, cogeneration power provided by the TEs 110, 120 may be
decreased to provide additional preheating of the preheated intake
gas 180 to enable operation of the fuel cell 104 or to improve
operational efficiency of the fuel cell 104. In another particular
embodiment, the controller 150 operates the control valves 152, 154
to maximize, optimize or otherwise control total power output
generated by the combination of the fuel cell 104 and the TEs 110,
120. For example, the controller 150 may monitor power output from
the TEs 110, 120 and may adjust the control valves 152, 154 to
maximize, optimize or otherwise control the power output based on a
control scheme.
[0027] In a particular embodiment, one or more components of the
system 100 may be merged with another component or may be omitted
from the system 100. For example, only one TE may be present, only
one control valve may be present, only one heat exchange may be
present, or any combination thereof.
[0028] In another particular embodiment, waste heat may be
recovered only from the hot exhaust gas 107 from the anode 106 or
only from the hot exhaust gas 109 from the cathode 108. In this
embodiment, only one set of heat recovery systems (such as the TEs
110, 120 and heat exchangers 130, 140), cogeneration systems (such
as the TEs 110, 120), and control systems (such as the control
valves 152, 154), may be present.
[0029] FIG. 2 is a diagram of a second embodiment of a system to
generate electric power, the system generally designated 200. In a
particular embodiment, the system 200 includes many elements that
are the same as or substantially similar to elements of the system
100. Such elements have the same reference number as in FIG. 1 for
ease of reference and description.
[0030] In the system 200, a controller 250 controls one or more
control valves 252, 254. The control valves 252, 254 are positioned
between a fuel cell outlet and a fuel cell inlet (rather than
between the fuel cell outlet and the heat exchanger hot-side inlet
as in the system 100 of FIG. 1). Thus, the control valves 252, 254
control an amount of the hot exhaust gases 107, 109 that bypass
both the TEs 110, 120 and the heat exchanger 130, 140. The control
valves 252, 254 are operable to control preheating of preheated
intake gas 280 routed to the fuel cell by controlling a portion of
the hot exhaust gases 107, 109 that is mixed directly into the
preheated intake gas 280. For example, a first portion of the hot
exhaust gases 107, 109 may be routed to an intake of the fuel cell
104 and a second portion of the hot exhaust gases 107, 109 may be
routed through the TEs 110, 120 and the heat exchanger 130, 140
based on a position of the control valves 252, 254.
[0031] FIG. 3 is a diagram of a third embodiment of a system to
generate electric power, the system generally designated 300. In a
particular embodiment, the system 300 includes many elements that
are the same as or substantially similar to elements of the system
100. Such elements have the same reference number as in FIG. 1 for
ease of reference and description.
[0032] In the particular embodiment of FIG. 3, no heat exchangers,
such as the heat exchangers 130 and 140 of FIGS. 1 and 2, are
present. Rather, TEs 310, 320 coupled to outlets of the fuel cell
104 exchange heat between the hot exhaust gases 107, 109 and the
intake gases 162 in addition to generating power based on a
temperature differential between the hot exhaust gases 107, 109 and
the intake gases 162. A controller 350 controls one or more control
valves 352, 354 that are positioned between the fuel cell outlet
and the fuel cell inlet. Thus, the control valves 352, 354 control
an amount of the hot exhaust gases 107, 109 that bypass TEs 310,
320. The control valves 352, 354 are operable to control preheating
of preheated intake gas 380 routed to the fuel cell 104 by
controlling a portion of the hot exhaust gases 107, 109 that is
mixed directly into the preheated intake gas 380 from the cold
sides 114, 124 of the TEs 310, 320.
[0033] FIGS. 4-6 are perspective end and side views, respectively,
of a thermoelectric generator (TE) 400 according to a particular
embodiment. The TE 400 may be any one or more of the TEs 110, 120
described with reference to FIGS. 1 and 2. The TE 400 a
thermoelectric device 412 generates electricity based on a
temperature differential between the hot side 414 of the
thermoelectric device 412 and the cold side 410 of the
thermoelectric device 412. In a particular embodiment, the hot side
414 has a hot-side inlet 430 and a hot side outlet 432. The hot
side 414 may be adapted to receive hot fluids 402, such as the hot
exhaust gases 107, 109 from a high temperature fuel cell, as
described with reference to FIGS. 1 and 2. The cold side 410 may
have a cold-side inlet 420 and a cold-side outlet 422. The cold
side 410 may be adapted to receive cold fluids 404, such as the
intake gases 162, as described with reference to FIGS. 1 and 2. It
is understood that "hot" and "cold" are relative terms and, as used
herein, indicate a temperature differential between the respective
fluids 402, 404. That is, the hot fluid 402 has a higher
temperature than the cold fluid 404.
[0034] The hot side 414 is separated from the cold side 410 by the
thermoelectric device 412. The thermoelectric device 412 may
include bimetal junctions, bismuth-telluride semiconductor
junctions, other materials capable of generating electric energy
based on temperature differentials, or any combination thereof. In
the illustrated embodiment, the TE 400 is radial or annular, with
the cold side 410 surrounding the hot side 414. That is, a region
of the TE 400 that receives hot fluids (the hot side 402) may be at
a center of a tube and may be separated from an outer region of the
TE 400 that receives cold fluids (the cold side 404) by the
thermoelectric device 412. In this embodiment, an outer casing 408
may be provided around the cold side 410. However, in other
embodiments the TE 400 may have a physical arrangement other than
annular, such as parallel plates. Also, the illustrated embodiment
is arranged for co-flow, or flow of the hot fluid 402 in the same
direction as the cold fluid 404. However, in other embodiments, the
TE 400 is counter flow, with the hot fluid 402 flowing in a
direction opposite the cold fluid 404. The TE 400 may also have
power connectors (not shown) to enable electricity generated by the
TE 400 to flow to a circuit.
[0035] FIG. 7 is a flow chart of a first embodiment of a method of
generating electric power, the method generally designated 700. The
method 700 may include, at 702, generating electric power using a
fuel cell. For example, the fuel cell 104 discussed with references
to FIGS. 1 and 2 may generate electric current using a chemical
reaction between a fuel and an oxidizer. In a particular
embodiment, the fuel cell may be a high temperature fuel cell, such
as a solid oxide fuel cell.
[0036] The method 700 may also include, at 704, generating
additional electric power using a thermoelectric generator (TE).
The TE may generate the additional electric power based on a
temperature differential across a thermoelectric device. For
example, the thermoelectric device 412 described with reference to
FIGS. 4-6 may be used to generate the additional electric power
based on a temperature differential between a cold side of the TE
and a hot side of the TE. In a particular embodiment, the method
700 includes, at 706, routing fuel cell exhaust from the fuel cell
to the hot side of the TE and, at 708, routing fuel cell intake
gases to the cold side of the TE. Thus, a temperature differential
between the fuel cell exhaust and the fuel cell intake gases may be
used to generate the additional electric power at the TE.
[0037] In a particular embodiment, operation of the fuel cell may
be enabled or operational efficiency of the fuel cell may be
improved when the fuel cell intake gases are preheated. In this
embodiment, the method also includes, at 710, preheating the fuel
cell intake gases by routing the fuel cell intake gases from the TE
through a heat exchanger (HX) to recover heat from the fuel cell
exhaust received from the hot side of the TE. The method may also
include, at 712, controlling preheating of the fuel cell intake
gases by adjusting a bypass valve. For example, a first portion of
the fuel cell exhaust may be routed to an intake of the fuel cell
and a second portion of the fuel cell exhaust may be routed through
the TE and the HX, at 714, based on a position of the bypass
valve.
[0038] FIG. 8 is a flow chart of a control scheme to control
generation of electric power according to a particular embodiment.
For example, the control scheme illustrates control laws that may
be used by a controller to manipulate control valves to regulate
power generated by a cogeneration system, such as the system 100 or
the system 200 as described with reference to FIG. 1 and FIG. 2,
respectively. The control scheme includes, at 802, setting control
parameters of the controller. The input parameters may include a
fuel cell minimum inlet temperature, T.sub.1, and a fuel cell
optimum (or desired) inlet temperature, T.sub.2. In a particular
embodiment, T.sub.2 may be selected to increase an amount of
electric power output by the fuel cell. For example, when the fuel
cell is a high-temperature fuel cell, T.sub.2 may be a relatively
high temperature, e.g., in the hundreds of degrees Celsius, to
improve operational efficiency of the fuel cell. T.sub.1 may be
selected based on operational criteria of the fuel cell. For
example, the fuel cell may generate minimal power or no power until
a minimum operational temperature of the fuel cell is reached.
T.sub.1 may be selected to keep the fuel cell above this minimum
operational temperature.
[0039] The input parameters may also include valve open angles,
such as a minimum valve open angle, .THETA..sub.min, and a maximum
valve open angle, .THETA..sub.max. The minimum valve open angle
.THETA..sub.min may be a minimum amount that a control valve, such
as one of the control valves 152, 154 of FIG. 1 or 252, 254 of FIG.
2, can be opened. The maximum valve open angle .THETA..sub.max may
be a maximum amount that the control valve can be opened.
[0040] At 804, the controller may monitor an inlet temperature,
T.sub.i, of the fuel cell. For example, a thermocouple or other
temperature monitoring device may detect, in real-time or near
real-time, the temperature of the intake gases 180 of FIG. 1 or the
temperature of the intake gases 280 of FIG. 2. Based on T.sub.i,
the controller may adjust an open angle .THETA..sub.ctrl, the
control variable, of the control valve. For example, at 806, when
T.sub.i minus T.sub.1 is less than 0 (zero), the controller may
adjust the valve open angle .THETA..sub.ctrl to be equal to the
maximum valve open angle .THETA..sub.max, at 808, to maximize
preheating of the fuel cell inlet gases. At 810, when T.sub.i minus
T.sub.2 is greater than 0 (zero), the controller may adjust the
valve open angle .THETA..sub.ctrl to be equal to the minimum valve
open angle .THETA..sub.min, at 812, to minimize preheating of the
fuel cell inlet gases. When T.sub.i minus T.sub.1 is not less than
0 (zero) and T.sub.i minus T.sub.2 is not greater than 0 (zero),
the controller may implement a control function, F(T.sub.i), to
select the valve open angle .THETA..sub.ctrl. For example, the
control function may be a proportional control function, a
derivative control function, an integral control function, another
control function, or any combination thereof.
[0041] FIG. 9 is a diagram further illustrating the control scheme
of FIG. 8, according to a particular embodiment. FIG. 9 includes a
graph 902 of the valve open angle versus the fuel cell inlet
temperature, T.sub.i, in one embodiment of the control scheme. The
graph 902 shows that, when T.sub.i is less than T.sub.1, the
control valve is opened to a maximum value, .THETA..sub.max.
Further, when T.sub.i is greater than T.sub.2, the control valve is
set to a minimum open angle (which may be closed), .THETA..sub.min.
When T.sub.i is between T.sub.1and T.sub.2, the angle of the
control valve is set according to a function that relates T.sub.i
to the control value angle, .THETA..sub.ctrl. FIG. 9 also
illustrates, at 904, the control valve and the control valve angle
.THETA..sub.ctrl and describes a relationship between mass flow
rate of fluid through the control valve based on the control valve
open angle .THETA..sub.ctrl.
[0042] FIG. 10 is a diagram of a first embodiment of a cooling
system. The cooling system is disposed in a vehicle 1000 that
includes an engine 1002 and one or more propulsion devices, such as
wheels 1056, fans, propellers, rotors, tracks, other devices
adapted to generate or control movement of the vehicle 1000, or any
combination thereof. For example, the engine 1002 may be an
internal combustion engine, such as a gasoline or diesel engine or
another type of piston or rotary engine, or a turbine engine or
other continuous combustion engine. During operation, the engine
1002 may generate heat that should be removed from the engine 1002
in order to maintain the engine 1002 at a temperature within a
specified operating temperature range. Thus, the vehicle 1000 may
include a cooling system to extract heat from the engine 1002. For
example, the engine 1002 may include an engine coolant inlet 1004
to receive a coolant 1060 (e.g., a second portion 1064 of the
coolant 1060) into the engine 1002 and an engine coolant outlet
1006 to remove the coolant 1060 from the engine 1002. The cooling
system may also be used to extract heat from one or more other
components 1040 of the vehicle 1000.
[0043] The coolant 1060 may be routed to a first heat exchanger
("HE") 1010 to extract waste heat from the coolant 1060 (e.g., to
reduce the temperature of the coolant 1060) so that the coolant
1060 can be cycled through the cooling system to remove additional
heat from the engine 1002 and the one or more other components 1040
of the vehicle 1000. In a particular embodiment, the coolant 1060
is supplied to the engine 1002 and to a second HE 1020, such as a
cold plate. For example, a first portion 1062 of the coolant 1060
may be routed to the second HE 1020 to provide cooling for the one
or more components 1040 of the vehicle 1000, and a second portion
1064 of the coolant 1060 may be routed to the engine 1002 to
provide cooling for the engine 1002.
[0044] In a particular embodiment, the first portion 1062 is the
same portion of the coolant as the second portion 1064. To
illustrate, the second HE 1020 and the engine 1002 may be coupled
via a conduit (e.g., pipe, tubing or ducts) to receive the coolant
1060 in series, as described with reference to FIG. 11. For
example, the first portion 1062 may be routed to a second HE inlet
1022 from a first HE outlet 1014 of the first HE 1010. The first
potion 1062 may pass through the second HE 1020 and exit from the
second HE 1020 via a second HE outlet 1024. After the coolant 1060
exits the second HE outlet 1024, the coolant 1060 may be routed as
the second portion 1064 to the engine coolant inlet 1004. Thus, the
first portion 1062 of the coolant 1060 may be cooler than the
second portion 1064 of the coolant 1060 since heat may be added to
the coolant 1060 by the second HE 1020.
[0045] In another particular embodiment, the first portion 1062 of
the coolant is different than the second portion 1064. To
illustrate, the second HE 1020 and the engine 1002 may be coupled
via conduit to the first HE 1010 to receive the coolant 1060 in
parallel. For example, the first portion 1062 may be routed to the
second HE inlet 1022 from the first HE outlet 1014, and the second
portion 1064 may be routed to the engine coolant inlet 1004 from
the first HE outlet 1014, as described with reference to FIG. 12.
Thus, in a parallel system, the first portion 1062 of the coolant
1060 may be at substantially the same temperature as the second
portion 1064 of the coolant 1060.
[0046] The vehicle 1000 may also include a thermoelectric cooling
device 1030 to facilitate cooling of the one or more components
1040 of the vehicle 1000. For example, the thermoelectric cooling
device 1030 may include a sold-state Peltier effect heat pump. A
cold side 1034 of the thermoelectric cooling device 1030 may be in
thermal communication with the one or more components 1040 of the
vehicle 1000. Heat may be transferred to the thermoelectric cooling
device 1030 from the one or more components 1040 of the vehicle
1000. The heat may pass from the cold side 1034 to a hot side 1032
of the thermoelectric cooling device 1030. The hot side 1032 of the
thermoelectric cooling device 1030 may be in thermal communication
with the second HE 1020. Thus, the second HE 1020 may receive heat
from the hot side 1032 of the thermoelectric cooling device 1030.
Heat may be extracted from the second HE 1020 by the coolant 1060.
The first portion 1062 of the coolant 1060 may be at a temperature
that is higher than a temperature of the one or more components
1040 of the vehicle 1000. For example, the temperature of the first
portion 1062 of the coolant 1060 may be higher than a specified
operating temperature of the one or more components 1040 of the
vehicle 1000. However, the thermoelectric cooling device 1030 may
drive heat against a temperature gradient to enable cooling of the
one or more components 1040 by the thermoelectric cooling device
1030 and the second HE 1020.
[0047] A control system 1050 may be used to control the temperature
of the one or more components 1040 by adjusting power supplied to
the thermoelectric cooling device 1030. For example, a rate at
which heat is extracted from the one or more components 1040 by the
thermoelectric cooling device 1030 may depend at least partially on
an amount of current supplied to the thermoelectric cooling device
1030. Thus, even when the first portion 1062 of the coolant 1060 is
received at the second HE 1020 at a temperature that is greater
than the specified operating temperature of the one or more
components 1040, the thermoelectric cooling device 1030 may enable
control of the temperature of the one or more components 1040 and
efficient heat transfer from the one or more components 1040 to the
coolant 1060.
[0048] In a particular embodiment, the vehicle 1000 also includes a
thermoelectric generator 1070 in thermal communication with the
first HE 1010. The thermoelectric generator 1070 may generate at
least a portion of power used by the thermoelectric cooling device
1030 using waste heat sent to the first HE 1010 via the coolant
1060 for disposition (e.g., removal from the coolant). For example,
the thermoelectric generator 1070 may be located between a hot side
1072 and a cold side 1074 of the first HE 1010. The thermoelectric
generator 1070 may generate power based on a temperature
differential between the hot side 1072 and the cold side 1074 of
the first HE 1010. In a particular embodiment, the thermoelectric
generator 1070 and the thermoelectric cooling device 1030 are each
Peltier effect devices. For example, the thermoelectric cooling
device 1030, the thermoelectric generator 1070, or both may be
thermoelectric generators such as the TEs described with reference
to FIGS. 1-6.
[0049] In a particular embodiment, the vehicle 1000 includes one or
more electric motors 1054. For example, the vehicle 1000 may be a
"hybrid vehicle" where the engine 1002 is used at least partially
to generate power that is used by the one or more electric motors
1054 to move the vehicle 1000. For example, the engine 1002 may
charge one or more batteries or other power sources 1052 that
supply power to the electric motors 1054 to turn the wheels 1056.
The thermoelectric generator 1070 may also be coupled to one or
more of the power sources 1052 to provide a portion of the power
used by the thermoelectric cooling device 1030 to cool the one or
more components 1040 of the vehicle 1000. The one or more
components 1040 of the vehicle 1000 that are cooled using the
second HE 1020 and the thermoelectric cooling device 1030 may
include components of a power conditioning system (such as a power
electronics module) that conditions power supplied to the one or
more electric motors 1054. Such components may include inverters,
transformers and other relatively high temperature, high power
electronic components.
[0050] In a particular embodiment, the vehicle 1000 is a land-based
vehicle, such as a car. In other particular embodiments, the
vehicle 1000 is a water-based vehicle, such as a boat, a ship or a
submarine. In still other embodiments, the vehicle 1000 may be an
aircraft, such as an airplane or a helicopter. In yet other
embodiments, the vehicle 1000 is a spacecraft, such as a satellite
or orbital vehicle. Regardless of the specific type of the vehicle
1000, the cooling system may reduce an overall weight of the
vehicle 1000 and a complexity or part count of the vehicle 1000 by
cooling both the engine 1002 and the one or more other components
1040 of the vehicle 1000 using a single cooling system despite a
large operating temperature difference between the engine 1002 and
the one or more other components 1040. Additionally, since an
operating efficiency of the one or more components 1040 may
decrease as the temperature of the one or more components 1040
increases, the cooling system may improve the operating efficiency
of the one or more components 1040 and potentially of the vehicle
1000 as whole. This may be so even though the thermoelectric
cooling device 1030 uses power to facilitate the transfer of heat
from the one or more components 1040 to the second HE 1020 because
the thermoelectric cooling device 1030 also increases a temperature
differential between the one or more components 1040 and the cold
side 1034 of the thermoelectric cooling device 1030. Still further
efficiency improvements may be gained when the thermoelectric
generator 1070 is used to convert a portion of the waste heat to
power.
[0051] FIG. 11 is a diagram of a second embodiment of a cooling
system 1100. The cooling system 1100 is arranged to cool two or
more heat sources, such as an engine 1102 and one or more
components 1140. For example, the cooling system may be part of the
vehicle 1000 of FIG. 10. In the embodiment illustrated in FIG. 11,
the cooling system 1100 routes a coolant flow from a first heat
exchanger ("HE") 1172 to a second HE 1120 that is in thermal
communication with the component 1140, from the second HE 1120 to
an engine cooling system 1104 and from the engine cooling system
1104 back to the first HE 1172. Thus, the second HE 1120 and the
engine cooling system 1104 are connected in series in the cooling
system 1100.
[0052] In a particular embodiment, the engine 1102 includes or is
in thermal communication with the engine cooling system 1104 to
receive waste heat generated at the engine 1102. For example, the
engine cooling system 1104 may receive the coolant at a first
temperature and release the coolant at a second temperature. The
second temperature may be higher than the first temperature due to
heat extracted from the engine 1102 by the coolant. For example,
the second temperature may be higher than the first temperature by
20.degree. C. to 30.degree. C. or more.
[0053] The first HE 1172 may include a radiator or a similar device
to extract heat from the coolant. For example, the first HE 1172
may include ribs, fins, or other devices that provide a large
surface area for heat exchange with an air stream 1178 from a
cooling fan 1176 to remove heat from the coolant. In another
example, the first HE 1172 may include devices that enable removal
of waste heat from the coolant into another coolant stream, removal
of the waste heat via radiation, or removal of waste heat via
another heat transfer process. Thus, the coolant may be received at
the first HE 1172 at a relatively high temperature and may exit
from the first HE 1172 at a cooler temperature.
[0054] In a particular embodiment, the component 1140 includes one
or more electronic devices, such as a power electronics module. The
engine 1102 and the component 1140 may have different specified
operating temperatures. For example, the engine 1102 may operate at
a significantly higher temperature than the component 1140. To
illustrate, certain components of the engine 1102 that are cooled
by the coolant may operate at temperatures significantly higher
than 100.degree. C. (e.g., more than 500.degree. C.). However, the
component 1140 may operate at 100.degree. C. or less. In a
particular embodiment, the component 1140 has a specified operating
temperature of 60-90.degree. C. In another particular embodiment,
the component 1140 has a specified operating temperature of
90-100.degree. C. The operating temperature of the engine 1102 may
depend on the specific type of the engine and other characteristics
of the engine 1102 and operating conditions of the engine 1102. For
example, when the engine 1102 is a gasoline engine, the operating
temperature may vary depending on the specific type of gasoline
used by the engine 1102 and depending on manufacturer's
specifications for the engine 1102. Likewise, operating
temperatures can vary widely for other types of the engines, such
as diesel and turbine engines. However, the specified operating
temperature of the engine 1102 is generally significantly higher
than 100.degree. C.
[0055] Since the engine 1102 may have a significantly higher
operating temperature than the component 1140, the coolant supplied
to the second HE 1120 from the first HE 1172 may be too hot to
enable sufficient cooling of the component 1140 based on a thermal
gradient between the component 1140 and the coolant. A
thermoelectric cooling device 1130 may be disposed between the
second HE 1120 and the component 1140 to facilitate transfer of
heat from the component 1140 to the coolant. The thermoelectric
cooling device 1130 may include a Peltier heat pump that drives
heat against a thermal gradient in response to a current supplied
to the thermoelectric cooling device 1130. Thus, even when the
coolant would not enable the second HE 1120 to extract sufficient
heat from the component 1140 to maintain the specified operating
temperature of the component 1140, the thermoelectric cooling
device 1130 can facilitate the heat transfer and facilitate cooling
of the component 1140.
[0056] The cooling system 1100 may also include a thermoelectric
generator 1170 in thermal communication with the first HE 1172. The
thermoelectric generator 1170 may generate power based on a
temperature differential between the coolant received at the first
HE 1172 from the engine 1102 and a cold side of the first HE 1172
(e.g., a portion of the first HE 1172 where heat is extracted by
the air stream 1178). The thermoelectric generator 1170 may include
a Peltier effect device that generates power based on a temperature
differential. At least a portion of the power generated by the
thermoelectric generator 1170 may be used to provide power to the
thermoelectric cooling device 1130 to facilitate cooling of the
component 1140. For example, the power generated by the
thermoelectric generator 1170 may be combined with power from
another power source 1152 (e.g., a battery) to power the
thermoelectric cooling device 1130. The power provided to the
thermoelectric cooling device 1130 may be controlled to control the
temperature of the component 1140.
[0057] FIG. 12 is a diagram of a third embodiment of a cooling
system 1200. The cooling system 1200 is arranged to cool two or
more heat sources, such as the engine 1102 and the component 1140.
The cooling system 1200 routes a first portion of a coolant flow
from the first HE 1172 to the second HE 1120 that is in thermal
communication with the component 1140 and from the second HE 1120
back to the first HE 1172. A second portion of the coolant flow is
routed from the first HE 1172 to the engine cooling system 1104 and
from the engine cooling system 1104 back to the first HE 1172.
Thus, the second HE 1120 and the engine cooling system 1104 are
connected in parallel in the cooling system 1200.
[0058] FIG. 13 is a flow chart of a particular embodiment a method
of cooling an engine and another component. The method may be
performed by the vehicle 1000 of FIG. 10 or by the cooling systems
1100 and 1200 of FIGS. 11 and 12, respectively.
[0059] The method includes, at 1302, routing at least a first
portion of a coolant stream from a first heat exchanger to a second
heat exchanger to receive heat from a hot side of a thermoelectric
cooling device. For example, the thermoelectric cooling device may
provide cooling for one or more electronic devices, such as a power
electronics module. The temperature of the first portion of the
coolant stream may be higher than a specified operating temperature
of the one or more electronic devices.
[0060] The method also includes, at 1304, cooling the one or more
electronic devices using a cold side of the thermoelectric cooling
device. For example, the thermoelectric cooling device may include
a solid-state Peltier effect heat pump. Thus, the cool side of the
thermoelectric cooling device may receive heat from the one or more
electronic devices and may transport the heat to a hot side of the
thermoelectric cooling device. The hot side of the thermoelectric
cooling device may be in thermal communication with the coolant
stream. For example, the hot side of the thermoelectric cooling
device may be in thermal contact with a second heat exchanger
through which the first portion of the coolant stream is
conveyed.
[0061] The method also includes, at 1306, routing at least a second
portion of the coolant stream to an engine. In a particular
embodiment, the second portion of the coolant stream is the same as
the first portion of the coolant stream. For example, the cold
plate and the engine may be coupled in series to receive the
coolant stream. To illustrate, the second heat exchanger and the
engine may be coupled as described with reference to FIG. 11. Thus,
the temperature of the first portion of the coolant stream when the
first portion is received at the second heat exchanger may be less
than a temperature of the second portion of the coolant stream when
the second portion is received at the engine. In another particular
embodiment, the second portion is different than the first portion.
For example, the second heat exchanger and the engine may be
coupled in parallel to receive different portions of the coolant
stream. To illustrate, the second heat exchanger and the engine may
be coupled as described with reference to FIG. 12. Thus, the
temperature of the first portion of the coolant stream when the
first portion is received at the second heat exchanger may be
substantially equal to the temperature of the second portion of the
coolant stream when the second portion is received at the
engine.
[0062] The method also includes, at 1308, controlling a temperature
of the one or more electronic devices by controlling power supplied
to the thermoelectric cooling device. For example, when the
thermoelectric cooling device is a solid-state heat pump, the
thermoelectric cooling device may drive heat from the cold side of
the thermoelectric cooling device to the hot side of the
thermoelectric cooling device. Thus, the heat may be received into
the coolant stream based on power provided to the thermoelectric
cooling device. To illustrate, when additional power is provided to
the thermoelectric cooling device, the thermoelectric cooling
device may extract more heat from the one or more electronic
devices per unit of time, and when less power is provided to the
thermoelectric cooling device, the thermoelectric cooling device
may extract less heat from the one or more electronic devices per
unit of time.
[0063] After receiving heat from the engine, the coolant stream may
be routed to the first heat exchanger, such as the first HE 1010 of
FIG. 10 for removal of the heat (i.e., waste heat from the engine
1002 and the components 1040). For example, the first heat
exchanger may include a radiator. The first heat exchanger may
remove heat from the coolant stream before routing the coolant
stream back to second heat exchanger and to the engine. The method
may include, at 1310, generating at least a portion of the power
supplied to the thermoelectric cooling device using a temperature
gradient at the first heat exchanger. For example, the first heat
exchanger may include a thermoelectric generator. The
thermoelectric generator may generate power based on the
temperature differential between a hot side of the first heat
exchanger and a cold side of the first heat exchanger. The power
generated by the thermoelectric generator may be routed to a power
storage device, such as a battery, or to the thermoelectric cooling
device to cool the one or more electronic devices.
[0064] Multiple use cooling systems (i.e., systems used to cool
more than one heat source) as disclosed herein may improve
efficiency, cost, and reliability as compared to using separate
cooling systems for two or more heat sources. Additionally, due to
the reduced number of parts compared to separate cooling systems,
the multiple use cooling systems may be lighter and take up less
space.
[0065] These improvements may be especially beneficial when the
multiple use cooling system is used in a vehicle to cool two or
more heat sources that have different operating temperatures. For
example, landcraft, watercraft, aircraft and spacecraft may each
include heat sources with different cooling requirements, such as
engines and electronic components. The electronic components may
have a significantly lower operating temperature than the engines.
In certain embodiments, a coolant used to cool the engine is hotter
than the operating temperature of the electronic components.
However, use of a thermoelectric cooling device, such as a
solid-state Peltier heat pump enables driving heat against a
temperature gradient to enable removal of heat from the electronic
devices by the higher temperature coolant. Use of a higher
temperature coolant to cool the electronic devices may improve
thermal performance of a radiator or other heat exchanger that
removes heat from the coolant. For example, in hot ambient
temperature environments, there may be only a small temperature
gradient between the operating temperature of the electronic
devices and the ambient temperature. However, when a coolant that
is at a higher temperature than the operating temperature of the
electronic devices is used, as in embodiments disclosed herein, a
larger temperature gradient is present between the coolant and the
ambient temperature, which improves the efficiency of heat transfer
from the coolant to the ambient environment.
[0066] Additionally, the thermoelectric cooling device enables
control of the temperature of the electronic components by
controlling power supplied to the thermoelectric cooling device.
Controlling the temperature of the electronic components can reduce
thermal stresses and improve reliability of the electronic
components. Accordingly, the multiple use cooling systems disclosed
can reduce cost, size, weight and complexity of cooling systems and
improve reliability of the cooling systems and the systems being
cooled (e.g., the engines and the electronic components).
[0067] Further, a thermoelectric generator may be used to convert
some of the waste heat from the electronic components and the
engine as power that can be supplied to the thermoelectric cooling
device. The thermoelectric generator may also reduce a thermal load
of the radiator by converting some of the waste heat received at
the radiator to power, enabling improved performance of the cooling
system.
[0068] The illustrations of the embodiments described herein are
intended to provide a general understanding of the structure of the
various embodiments. The illustrations are not intended to serve as
a complete description of all of the elements and features of
apparatus and systems that utilize the structures or methods
described herein. Many other embodiments may be apparent to those
of skill in the art upon reviewing the disclosure. Other
embodiments may be utilized and derived from the disclosure, such
that structural and logical substitutions and changes may be made
without departing from the scope of the disclosure. Additionally,
the illustrations are merely representational and may not be drawn
to scale. Certain proportions within the illustrations may be
exaggerated, while other proportions may be reduced. Accordingly,
the disclosure and the figures are to be regarded as illustrative
rather than restrictive.
[0069] Although specific embodiments have been illustrated and
described herein, it should be appreciated that any subsequent
arrangement designed to achieve the same or similar purpose may be
substituted for the specific embodiments shown. This disclosure is
intended to cover any and all subsequent adaptations or variations
of various embodiments. Combinations of the above embodiments, and
other embodiments not specifically described herein, will be
apparent to those of skill in the art upon reviewing the
description.
[0070] The Abstract of the Disclosure is provided with the
understanding that it will not be used to interpret or limit the
scope or meaning of the claims. In addition, in the foregoing
Detailed Description, various features may be grouped together or
described in a single embodiment for the purpose of streamlining
the disclosure. This disclosure is not to, be interpreted as
reflecting an intention that the claimed embodiments require more
features than are expressly recited in each claim. Rather, as the
following claims reflect, claimed subject matter may be directed to
less than all of the features of any of the disclosed
embodiments.
[0071] The above-disclosed subject matter is to be considered
illustrative, and not restrictive, and the appended claims are
intended to cover all such modifications, enhancements, and other
embodiments, which fall within the scope of the present disclosure.
Thus, to the maximum extent allowed by law, the scope of the
disclosure is to be determined by the broadest permissible
interpretation of the following claims and their equivalents, and
shall not be restricted or limited by the foregoing detailed
description.
* * * * *