U.S. patent application number 17/165155 was filed with the patent office on 2021-08-19 for solar thermal receivers with multi-scale light trapping geometry and features.
The applicant listed for this patent is The Australian National University, National Technology & Engineering Solutions of Sandia, LLC. Invention is credited to Joshua Mark Christian, Clifford K. Ho, Jesus Daniel Ortega, John Downing Pye.
Application Number | 20210254861 17/165155 |
Document ID | / |
Family ID | 1000005556971 |
Filed Date | 2021-08-19 |
United States Patent
Application |
20210254861 |
Kind Code |
A1 |
Ho; Clifford K. ; et
al. |
August 19, 2021 |
SOLAR THERMAL RECEIVERS WITH MULTI-SCALE LIGHT TRAPPING GEOMETRY
AND FEATURES
Abstract
Solar receivers including a plurality of multi-scale solar
absorbing surfaces arranged such that light or heat reflected from
or emitted from one or more of the plurality of solar absorbing
surfaces impinges one or more other solar absorbing surfaces of the
solar receiver. The disclosed receivers increase the amount of
absorbed energy from a concentrated light source, such as a
heliostat field, and reduce radiative and convective heat
losses.
Inventors: |
Ho; Clifford K.;
(Albuquerque, NM) ; Christian; Joshua Mark;
(Albuquerque, NM) ; Pye; John Downing; (Acton,
AU) ; Ortega; Jesus Daniel; (Albuquerque,
NM) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
National Technology & Engineering Solutions of Sandia, LLC
The Australian National University |
Albuquerque
Acton |
NM |
US
AU |
|
|
Family ID: |
1000005556971 |
Appl. No.: |
17/165155 |
Filed: |
February 2, 2021 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
14743319 |
Jun 18, 2015 |
10935281 |
|
|
17165155 |
|
|
|
|
14535100 |
Nov 6, 2014 |
10295224 |
|
|
14743319 |
|
|
|
|
62015052 |
Jun 20, 2014 |
|
|
|
61901628 |
Nov 8, 2013 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F24S 30/422 20180501;
F24S 10/72 20180501; F24S 2010/71 20180501 |
International
Class: |
F24S 10/70 20060101
F24S010/70; F24S 30/422 20060101 F24S030/422 |
Goverment Interests
STATEMENT CONCERNING FEDERALLY SPONSORED RESEARCH
[0002] This invention was developed under Contract
DE-AC04-94AL85000 between Sandia Corporation and the United States
Department of Energy and pursuant to Contract No. DE-NA0003525
between the United State Department of Energy and National
Technology and Engineering Solutions of Sandia, LLC, for the
operation of the Sandia National Laboratories. The U.S. Government
has certain rights in this invention.
Claims
1. A solar receiver, comprising: a flat support panel; and a
plurality of solar panels attached to and extending from the
support panel, the plurality of solar panels comprising a leading
edge distant from the flat support panel and an opposing trailing
edge proximate the flat support panel; wherein the plurality of
solar panels is attached to the flat support panel in a vertically
stacked configuration such that the trailing edges are attached to
the flat support panel in parallel; and wherein one or more of the
plurality of solar panels is arranged to reflect or radiate solar
energy to one or more other solar panel of the plurality of solar
panels to trap the reflected or radiated solar energy.
2. The solar receiver of claim 1, wherein at least one solar
receiver panel of the plurality of solar receiver panels are
pivotally attached to the support panel.
3. The solar receiver of claim 1, wherein the solar receiver is at
least 85% efficient.
4. The solar receiver of claim 1, wherein the plurality of solar
panels contains a heat transfer fluid during operation, wherein the
heat transfer fluid is introduced at a first temperature at the
leading edge and is removed at a second temperature greater than
the first temperature at the trailing edge during operation.
5. The solar receiver of claim 1, wherein one or more of the
plurality of solar panels comprises a plurality of tubes.
6. The solar receiver of claim 5, wherein the plurality of tubes
comprises leading surfaces offset between 0 and 45 degrees from an
adjacent tube. The solar receiver of claim 5, wherein the plurality
of tubes has a circular cross section that is offset by 30
degrees.
8. The solar receiver of claim 5, wherein the plurality of tubes
has a diamond cross section that is offset by 0 degrees.
9. The solar receiver of claim 5, wherein the plurality of tubes
has a cross-section selected from a group consisting of circular,
rectangular, square and diamond.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional application and claims
priority to U.S. patent application Ser. No. 14/743,319, entitled
"SOLAR THERMAL RECEIVERS WITH MULTI-SCALE LIGHT TRAPPING GROMETRY
AND FEATURES," filed Jun. 18, 2015, which claims priority to U.S.
Provisional Patent Application 62/015,052, filed Jun. 20, 2014,
entitled "Fractal Materials and Designs with Optimized Radiative
Properties," and is a Continuation-in-Part of U.S. patent
application Ser. No. 14/535,100, filed Nov. 6, 2014, titled "BLADED
SOLAR THERMAL RECEIVERS FOR CONCENTRATING SOLAR POWER," which
claims priority to U.S. Provisional Patent Application No.
61/901,628, filed Nov. 8, 2013, titled "SOLAR THERMAL ADVANCED
RECEIVER FOR CONCENTRATING SOLAR POWER TOWERS," all of which are
incorporated herein by reference in their entireties.
FIELD OF THE INVENTION
[0003] The present invention relates to solar thermal receivers,
and more particularly to solar thermal receivers having multi-scale
structures and geometries that increase effective solar absorptance
and efficiency.
BACKGROUND OF THE INVENTION
[0004] Mounting concerns over the effect of greenhouse gases on
global climate have stimulated research focused on limiting
greenhouse gas emissions. Solar power generation is particularly
appealing because substantially no greenhouse gases are produced at
the power generation source.
[0005] Concentrated solar power (CSP) generation using solar
receivers is known in the art. Briefly, concentrated solar power
systems use lenses, mirrors, or other elements to focus sunlight
incident on a relatively large area onto a small area called a
solar receiver. The concentrated sunlight can be used to heat a
fluid within the solar receiver. The fluid heated within the solar
receiver can be used to create energy, such as by driving a turbine
to generate power or by providing a secondary heat source.
[0006] Conventional receivers for concentrating solar power consist
of panels of tubes that are arranged in a cylindrical or cubical
shape to face the incoming solar irradiance. However, these
configurations also maximize radiative and convective heat losses
to the environment; most of the sunlight reflected off of these
surfaces is lost to the environment. For example, at high
temperatures (receivers can reach 600.degree. C. and higher), the
radiative heat loss (.about.T4) is significant. Previous receivers
have attempted to minimize these losses by increasing solar
absorptivity and reducing thermal emissivity of coatings at the
micro scale; however, very little research has investigated the
optimization of features and radiative processes of receivers and
other components at the meso and macro scales (millimeters to
meters).
[0007] The need therefore remains for an efficient solar receivers
that yield high solar absorptance and thermal efficiency and that
enable higher efficiency power cycles. In addition, a need exists
to alleviate the need for expensive coatings that degrade and need
to be reapplied.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is an illustration of a solar receiver according to
an exemplary embodiment of the disclosure.
[0009] FIG. 2 is an illustration of a solar receiver panel
according to an exemplary embodiment of the disclosure.
[0010] FIG. 3A is an illustration of a section of solar collection
tubes taken from between lines B'-C' according to an embodiment of
the disclosure.
[0011] FIG. 3B is a top view of the section of tubes of FIG.
3A.
[0012] FIG. 4A is another section of tubes according to another
embodiment of the disclosure.
[0013] FIG. 4B is a top view of the section of tubes of FIG.
4A.
[0014] FIG. 5A is another section of tubes according to another
embodiment of the disclosure.
[0015] FIG. 5B is a top view of the section of tubes of FIG.
5A.
[0016] FIG. 6A is another section of tubes according to another
embodiment of the disclosure.
[0017] FIG. 6B is a top view of the section of tubes of FIG.
6A.
[0018] FIG. 7 illustrates an array of tubes rotated 45 degrees from
the X axis.
[0019] FIG. 8A illustrates an array of diamond cross section tubes
offset 0 degrees according to an embodiment of the disclosure.
[0020] FIG. 8B illustrates an array of diamond cross section tubes
offset 15 degrees according to an embodiment of the disclosure.
[0021] FIG. 9 illustrates another tube design according to an
embodiment of the disclosure.
[0022] FIG. 10 is an illustration of another solar receiver panel
according to another exemplary embodiment of the disclosure.
[0023] FIG. 11 is an illustration of examples of solar receivers
and tube designs according to another exemplary embodiment of the
disclosure.
[0024] FIG. 12 is an illustration of another solar receiver panel
according to another exemplary embodiment of the disclosure.
[0025] FIG. 13 is an illustration of another solar receiver
according to another exemplary embodiment of the disclosure.
[0026] FIG. 14 is an illustration of another solar receiver panel
system according to an exemplary embodiment of the disclosure.
[0027] FIG. 15 is a partial cut away overhead view of one of the
solar receiver panel system of the solar receiver shown in FIG. 14
having the top headers cut away to show the tubes.
[0028] FIG. 16 is an illustration of another solar receiver
according to another exemplary embodiment of the disclosure.
[0029] FIG. 17 shows simulated thermal efficiency as a function of
intrinsic material solar absorptance for flat and finned
geometries.
[0030] FIG. 18 shows increase in effective absorptance as a
function of intrinsic material solar absorptance for flat and
finned geometries.
SUMMARY OF THE DISCLOSURE
[0031] The present disclosure is directed to solar receivers that
include a plurality of solar absorbing surfaces arranged such that
light or heat reflected from or emitted from, respectively, one or
more of the plurality of solar absorbing surfaces impinges one or
more other solar absorbing surfaces of the solar receiver. The
disclosed receivers reduce the local radiative view factors and
heat losses and increase the amount of absorbed energy from a
concentrated light source, such as a heliostat field.
[0032] In an embodiment of the disclosure, a solar receiver is
disclosed that includes a plurality of solar panels capable of
absorbing solar energy disposed radially about a central hub having
a vertical axis. One or more of the plurality of solar panels is
arranged to reflect and/or radiate solar energy to one or more
other solar panels to trap the reflected and/or radiated solar
energy.
[0033] In an embodiment of the disclosure, a solar receiver is
disclosed that includes a support panel is disclosed that includes
a plurality of solar panels attached to and extending from the
support panel. One or more of the plurality of solar panels is
arranged to reflect and/or radiate solar energy to one or more
other solar panel to trap the reflected and/or radiated solar
energy.
[0034] One advantage of the present disclosure is to provide a
solar receiver that will significantly increase the absorbed solar
radiation while reducing heat losses (radiative and convective),
yielding higher thermal efficiencies, improved performance, and
reduced costs for concentrating solar power tower systems.
[0035] Another advantage of the present disclosure is to provide a
solar receiver that will significantly increase thermal
efficiencies of solar energy receivers and a broad range of thermal
collection devices for sustainable, lower-cost, high-efficiency
energy conversion.
[0036] Another advantage of the present disclosure is that the
receiver footprint (optical intercept area) can be smaller with the
same exposed surface area and surface irradiance, which will reduce
heat losses. Large structural cavities, which are used to reduce
radiative heat losses, can also be avoided.
[0037] Another advantage of the present disclosure is that the
designs can reduce thermal emittance by reducing local view factors
in hottest regions.
[0038] Other features and advantages of the present disclosure will
be apparent from the following more detailed description of the
preferred embodiment, taken in conjunction with the accompanying
drawings which illustrate, by way of example, the principles of the
disclosure.
DETAILED DESCRIPTION OF THE DISCLOSURE
[0039] The present invention now will be described more fully
hereinafter with reference to the accompanying drawings, in which
preferred embodiments of the invention are shown. This invention
may, however, 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 be
thorough and complete and will fully convey the scope of the
invention to those skilled in the art.
[0040] The present disclosure is directed to solar receivers,
hereinafter referred to as "receivers," that reduce the amount of
radiative energy loss while increasing absorbed radiation, yielding
higher thermal efficiencies, improved performance, and reduced
costs for concentrating solar power tower systems. The disclosed
receivers include one or more solar absorbing structures or panels
arranged such that light reflected from or radiate heat from one or
more solar absorbing panels or surfaces impinges one or more other
solar absorbing panels or surfaces of the solar receiver. In such a
manner, the reflected and/or radiated energy that impinges and is
absorbed is "trapped" by the other panels or surfaces. The
arrangement of panels or surfaces having this functionality at
multiple length scales may be referred to as a "fractal"
arrangement or feature. The panels and/or surfaces may have a major
plane arranged vertically or horizontally relative to the earth. In
another embodiment, the panels or surfaces may have a major plane
angle arranged between vertical and horizontal. The disclosed
arrangement maximizes solar absorption while minimizing radiative
heat loss by trapping solar irradiation at multiple scales. In
addition, the disclosed fractal structures reduce local view
factors and thermal emittance. One or more of the solar absorbing
panels include one or more solar absorbing surfaces that reflect
light and/or radiate heat to one or more of the solar absorbing
panels. The solar absorbing surfaces may be flat, curved, wavy,
pleated, irregular or combinations thereof.
[0041] In the present disclosure, the term "macro" refers to meter
scale between 0.1 m and 10 m. Additionally, the term "meso" refers
to millimeter to centimeter scale from 0.1 mm to up 100 mm.
According to the present disclosure, the arrangement of solar
panels, or macro scale arrangement, may trap up to 40% of reflected
and emitted energy, and the arrangement of tubes, or meso scale
arrangement, may trap up to 30% of reflected and emitted energy. In
an embodiment, the arrangement of receiver panels, or macro scale
arrangement, may trap up to 5% of reflected and emitted energy, and
the arrangement of tubes, or meso scale arrangement, may trap up to
5% of reflected and emitted energy. The amount of reflected solar
energy that can be recaptured by the multi-scale designs depends,
in part, on the intrinsic solar absorptance of the material. The
increase in effective solar absorptance is greater when the
intrinsic solar absorptance is lower.
[0042] The disclosed receiver can operate at high temperatures
(>650.degree. C.) while reducing radiative and convective heat
losses at high concentration ratios (.about.1000 suns or more) to
achieve high annual thermal efficiencies. In an embodiment, the
disclosed receiver may reduce radiative view factors by up to 70%
and total heat loss by 50% with an increase in thermal efficiency
of nearly 10%. This translates into significant cost savings by
requiring fewer heliostats for the same amount of thermal output.
Achieving these metrics is necessary to reduce the levelized cost
of electricity of concentrating solar power towers to levels
comparable with current fossil-fueled power plants.
[0043] The disclosed solar receivers have increased or improved
efficiency compared to conventional receivers. In an embodiment,
the disclosed receivers may be at least 85% efficient. In another
embodiment, the solar receivers may be at least 90% efficient. In
another embodiment, the solar receivers may be at least 95%
efficient.
[0044] The disclosed receivers reduce view factors and thermal
emittance at multiple scales (panels and surfaces). Incorporation
of these fractal features and designs at multiple scales (microns
to meters) significantly increase thermal efficiencies of solar
energy receivers and a broad range of thermal collection devices
for sustainable, lower-cost, high-efficiency energy conversion.
[0045] FIG. 1 illustrates an embodiment of the present disclosure.
According to this embodiment, a receiver 10 is disclosed that
includes a plurality of blades or receiver panels (panels) 12
radially disposed about and extending from a central hub 14. The
panels 12 may be referred to as blades. In this exemplary
embodiment, the panels 12 radiate perpendicular from the central
axis Y of the hub 14. The hub 14 is connected to a tower 16 for
elevating the receiver 10 above a surface (not shown), such as the
ground. The panels 12 have a leading edge 17 that is distant from
the hub 14, and a trailing edge 18 that is proximate to the hub 14.
As such, the trailing edge is located where the local radiative
view factors are lower than at the leading edge, or in other words,
the trailing edge is toward the interior of the receiver. In this
and in other drawings of the disclosure, the hub and other
components are not necessarily to scale, and may be large enough to
contain piping and other features within. Each segment of the
radial structure can be modular, consisting of the outward radial
panels and the portion of the hub that connects the radial panels.
In this exemplary embodiment, the panels 12 have a generally
rectangular geometry or shape, with the major plane of the shape
perpendicular to the mounting surface or ground. In another
embodiment, the panels 12 have a rectangular, square, wedge or
other shape.
[0046] Additionally, the panels 12 have a first side 19 and a
second side 20 opposite the first side 19. The first and second
sides 19, 20 may be coated or treated with heat absorbing surfaces,
coatings or textures to efficiently capture the incident
concentrated solar radiation. As can be seen in FIG. 1, both first
and second sides 19, 20 sides of the panels 12 can be
illuminated.
[0047] The radially extending blade design increases the effective
solar absorptance and efficiency by providing a light trap for the
incident solar radiation while reducing heat losses from radiation
and convection. Light impinging upon the panels 12 is all or
partially reflected to an adjacent and/or other panel. Thermal
radiation emitted from panels 12 is all or partially directed to
adjacent or other panels. Convective heat loss from panels 12 is
all or partially absorbed by adjacent and/or other panels. In an
embodiment, the receiver 10 has been shown to reduce radiative view
factors by up to 70% and total heat loss by 50% with an increase in
thermal efficiency of nearly 10%.
[0048] In this exemplary embodiment, the receiver 10 includes eight
panels 12, however, in another embodiment, the receiver 10 may
include 2 or more panels 12. In another embodiment, the receiver 10
may include between 2 and 1000 panels. In another embodiment, the
receiver 10 may include between 3 and 20 panels. In another
embodiment, the receiver 10 may include between 4 and 10 panels. As
can be seen in FIG. 1, both sides of the panels 12 can be
illuminated.
[0049] The hub 14 provides a central attachment point for the
panels 12. In addition, the hub 14 and/or tower 16 may include
piping for fluidly connecting the panels 12 to a fluid source and
fluid receiver (not shown) as would be appreciated by one of
ordinary skill in the art. Further in addition, the hub 14 and/or
tower 16 may include pumps, valves and/or other fluid transport and
control devices for providing and/or controlling fluid to the
panels 12.
[0050] In this exemplary embodiment, the panels 12 are attached to
the hub 14. In another embodiment, the panels 12 may be pivotally
attached to the hub 14 in a manner that allows the panels 12 to
pivot about the Y axis. For example, one or more of the panels 12
may pivot so as to face a surface more perpendicular to solar
irradiance.
[0051] FIG. 2 illustrates an example of a receiver panel 12
according to an embodiment of the invention. As can be seen in FIG.
2, the receiver panel 12 includes a first manifold 22, a second
manifold 24, and a plurality of conduits or tubes 26 disposed
between the first and second manifolds 22, 24. In this exemplary
embodiment, the first manifold 22 receives a fluid from the hub 14
or tower 16 in the direction shown by arrow A. The fluid is then
distributed to the plurality of tubes 26 and flows in direction A'
to the second manifold 24, where it is collected and flows to the
hub 14 or tower 16 in direction A''. In another embodiment, the
direction of flow may be reversed. The first and second manifolds
22, 24 may include piping, baffling or other fluid control and
distribution components to provide and control the flow of fluid to
the tubes 26. In this exemplary embodiment, the tubes 26 have a
generally circular cross section. In another embodiment, the tubes
26 may have other cross sections, such as, but not limited to
square, rectangular, oval, diamond, hexagonal or other shape that
fully or partially reflect light to an adjacent and/or other panel
or tube and/or emit thermal radiation fully or partially to
adjacent or other panels or tubes. Additionally, in this exemplary
embodiment, the tubes 26 are in close proximity or touching
adjacent tubes. In an embodiment, some minimal spacing may be
present to allow for expansion. In an embodiment, panels 12 may
include one or more tubes with or without a manifold.
[0052] FIG. 3A illustrates section of tubes 26 taken between line
B' and C' of FIG. 2. FIG. 3B is a top view of tubes 26 of FIG. 3.
As can be seen in FIG. 3, the tubes 26 have a tube axis Y that
extends along the central axis of the tube. As can be seen in FIG.
4, the tube axis is aligned along axis X, which will be referred to
as the tubes having zero (0) degree offset. Also, the tube leading
edges 27 in the Z direction are aligned or have a 0 degree offset
along the X axis. The direction of incoming light is from the Z
direction.
[0053] FIGS. 4A and 4B illustrate tubes 26 having 15 degree offset,
or in other words the angle between adjacent tube's tube axis along
the X axis is 15 degrees. FIGS. 5A and 5B and 6B and 6B illustrate
tubes having 30 degree and 45 degree offset, respectively. In
another embodiment, the tubes may have a leading edge offset as a
result of adjacent tubes of different cross-section size, shape,
diameter and/or geometry. In another embodiment, tubes may be
offset by between greater than 0 degrees and less than 45 degrees.
In an embodiment, circular cross section tubes may be offset 30
degrees. FIG. 7 illustrates the array of tubes rotated 45 degrees
from the X axis.
[0054] FIGS. 8A and 8B illustrate diamond cross sectional tubes 926
having 0 and 15 degree offset, respectively. The diamond cross
sectional tubes 926 may be arranged according to any of the
embodiments discussed above.
[0055] FIG. 9 illustrates a finned tube 1026 having a central tube
component 1028 and fins 1030. In this exemplary embodiment, the
finned tube 1026 has 4 fins 1030. In another embodiment, the finned
tube 1026 may have two or more fins 1030. The finned tubes 1026 may
be arranged according to any of the embodiments discussed
above.
[0056] In an embodiment, a plurality of circular cross section or
cylindrical tubes is offset between 0 and 45 degrees from an
adjacent tube. For cylindrical tubes, the offset is to both the
tube center axis and the leading edge. In an embodiment, a
plurality of circular cross-section or cylindrical tubes is offset
30 degrees from an adjacent tube. In another embodiment, a
plurality of diamond cross-section tubes is offset by 0
degrees.
[0057] FIG. 10 illustrates an example of a multi-scale receiver
1040. The receiver 100 is at the macro scale (left), and the tubes
1045 shown to the right, which are at the meso scale, form the
panels 1050 of the receiver 1040. The tubes carry heat transfer
fluid and form the panels of tubes at the macro scale with similar
light-trapping geometries. In this exemplary embodiment, the tubes
1045 include fins 1055 having passages 1060 for the heat transfer
fluid.
[0058] FIG. 11 illustrates examples of multi-scale receiver designs
at the macro (left) and meso (right) scales. The meso-scale designs
are tubes that carry the heat transfer fluid and form the panels of
tubes at the macro scale with similar light-trapping
geometries.
[0059] FIG. 12 illustrates another example of a panel 32 according
to another embodiment of the disclosure. As can be seen in FIG. 12,
the panel 32 includes receiver sub-panels 34. Panel 32 includes a
leading edge 17, a trailing edge 18, a first side 19, and a second
side 20 (opposite the first side 19, but not shown). In this
exemplary embodiment, the panel 32 includes three sub-panels 34. In
another embodiment, the panel 32 may include two or more
sub-panels. Fluid flow is indicated by arrows B. In another
embodiment, the direction of fluid flow may be reversed. In another
embodiment, the fluid may enter the first bottom sub-panel and be
redirected to the tubes (as would be the case if the panel were
flipped so the bottom header was the top header. In another
embodiment, the fluid direction of the flipped receiver panel may
be reversed. In this exemplary embodiment, fluid is first provided
to the tubes of the panel closest to the leading edge 17. In
another embodiment, fluid may be first provided to the tubes of the
panel closest to the trailing edge 18.
[0060] Each receiver sub-panel 34 includes a first manifold 36, a
second manifold 38, and a plurality of tubes 40 receiving fluid
flow the first manifold 36 and providing fluid to the second
manifold 38. The first and second manifolds 36, 38 may include
piping, baffling or other fluid control and distribution components
to provide and control the flow of fluid to the tubes 40. In this
exemplary embodiment, the tubes 40 have a generally circular cross
section. In another embodiment, the tubes 40 may have other cross
sections, such as, but not limited to square, rectangular, and
oval.
[0061] By providing fluid to the leading edge first, the fluid
reaches maximum temperature furthest away from the leading edge, in
this example, closest to the central axis Y of the hub 14. In this
case, the hottest surfaces of the receiver panels are located in
the interior regions where the local view factors to the
environment are lowest. This will reduce the radiative heat loss.
In addition, heat loss by convection can be recuperated when the
hot air moves from the hotter interior regions to the cooler
exterior regions, essentially preheating the cooler surfaces.
[0062] FIGS. 13, 14 and 15 illustrate another exemplary embodiment
of a receiver 66 according to an embodiment of the disclosure. As
can be seen in FIG. 14, the receiver 66 includes a plurality of
receiver panel systems 68 connected to and radially disposed about
a central hub 70. The plurality of receiver panel systems 68 extend
from the central hub 70 in a radial direction. In this exemplary
embodiment, the radial axis of the receiver panel systems 68
radiate perpendicular from the central axis Y of the hub 70 in
radial direction R. The hub 70 is connected to a tower 72 for
elevating the receiver 66 above a surface (not shown). The receiver
panel systems 68 have a leading edge 74 that is distant from the
hub 70, and a trailing edge 76 that is proximate to the hub 70.
[0063] As can be seen in FIGS. 14 and 15, the receiver panel system
68 include a first receiver panel 78 and a second receiver panel 80
that generally come together to form a wedge or triangular shape
that apexes in the radial direction. The receiver panel system 68
may include a nose panel, cap or other structural member 82 that
provides structural support and aerodynamic streamlining to the
receiver panel system 68. The receiver panel system 68 may further
include a rear panel, cap or structural member 84 that provides
structural support and connection to the hub 70. The receiver panel
system 68 includes a first side 86 and a second side 88. In
addition, the receiver panel system 68 may include insulation
and/or reflective material or components 90 disposed behind the
first and/or second receiver panels 78, 80 for providing thermal
control and/or for reflecting irradiance back upon the sub-panels.
The receiver panel system 68 may include additional structures and
supports for joining and/or supporting the panel components.
[0064] In this exemplary embodiment, the receiver 66 includes four
receiver panel systems 68, however, in another embodiment, the
receiver 66 may include 2 or more receiver panel systems 68. In
another embodiment, the receiver 66 may include between 2 and 1000
receiver panel systems. In another embodiment, the receiver 66 may
include between 3 and 20 receiver panel systems. In another
embodiment, the receiver 66 may include between 4 and 10 receiver
panel systems. In an embodiment, receiver panels forming the
receiver panel systems may include one or more tubes with or
without a header. As can be seen in FIG. 5, both sides of the
receiver 66 can be illuminated.
[0065] The hub 70 provides a central attachment point for the
receiver panel systems 68. In addition, the hub 70 and/or tower 72
may include piping for fluidly connecting the receiver panel
systems 68 to a fluid source and fluid receiver (not shown) as
would be appreciated by one of ordinary skill in the art. Further
in addition, the hub 70 and/or tower 72 may include pumps, valves
and/or other fluid transport and control devices for providing
and/or controlling fluid to the receiver panel systems 68.
[0066] In this exemplary embodiment, the receiver panel systems 68
are attached to the hub 70. In another embodiment, the receiver
panel systems 68 may be pivotally attached to the hub 70 in a
manner that allows the receiver panel systems 68 to be pivoted
about the Y axis. For example, one or more of the 68 may be pivoted
so as to face a surface more perpendicular to solar irradiance.
[0067] FIGS. 14 and 15 show a more detailed illustration of a
receiver panel system 68 according to an embodiment of the
invention. The rear cap 80 has been removed from FIG. 13 for
clarity. As can be seen in FIGS. 14 and 15, the first and second
receiver panels 78, 80 are similar in shape and structure, and will
described by referencing the first receiver panel 78, while being
understood that corresponding similar components are shown on the
second receiver panel 80. The first receiver 78, which has a
general panel structure, includes variations as discussed with the
various embodiments, including, but not limited to being
constructed of a single panel. In addition, this embodiment may
include piping and/or other structures that may allow for fluid to
be provided between the first and second receiver panels 78, 80. It
should be noted that in this embodiment, illumination does not
directly impact the interior side of the tubes of the sub-panels,
although sunlight may be reflected to the interior side of the
tubes.
[0068] FIG. 16 illustrates another example of a receiver 92
according to another embodiment of the disclosure. As can be seen
in FIG. 18, the receiver 92 includes a support panel 94 and
plurality of blades or panels 96. The support panel 94 serves a
similar function as the hub 14 (FIG. 1) of a previous embodiment,
and may include piping, pumps, and fluid and support structures.
The plurality of receiver panels 96 extend from the plane of the
receiver 92. In an embodiment, the support panel 94 may be attached
to a tower as also shown in FIG. 1. The extending blade design
increases the effective solar absorptance and efficiency by
providing a light trap for the incident solar radiation while
reducing heat losses from radiation and convection.
[0069] The panels 96, which have a general panel structure, are
structured similar to the receiver panel 32 shown on FIG. 2, and
includes the variations as discussed above with the various
disclosed panel embodiments, including, but not limited to being
constructed of a single panel or multiple panels. The panels 96
include the various embodiments of tubes and arrangements as
disclosed above. In addition, the panels 96 include the various
embodiments of flow patterns as disclosed above. In particular, the
flow within the tubes within the panels may be from the panel
leading edge to the trailing edge (as shown by the dashed line), so
as to provide for the panel's highest temperature nearest the
support panel 94.
[0070] In this exemplary embodiment, the support panels 96 are
aligned and attached horizontally to the support panel 94, or in
other words, the flow in the tubes is horizontal in relation to any
surface the receiver 92 is disposed above, and as similarly shown
in FIG. 3. In another embodiment, the panels 96 may be aligned and
attached vertically upon the support panel 94. In another
embodiment, the receiver panels 96 may be attached at any angle to
the support panel 92. In this exemplary embodiment, the receiver
panels 96 are rigidly attached to the support panel 94. In another
embodiment, the receiver panels 96 may be pivotally attached to the
support panel 94.
[0071] FIG. 17 shows simulated thermal efficiency as a function of
intrinsic material solar absorptance for flat and finned geometries
at the meso scale. As can be seen in FIG. 17, the thermal
efficiency (energy absorbed divided by the incident energy) for the
finned geometry is greater than thermal efficiency of the flat
geometry. The finned geometry consisted of rectangular channels
similar to that shown in FIG. 11. The increase in thermal
efficiency is more pronounced when the intrinsic material solar
absorptance is lower.
[0072] FIG. 18 shows increase in effective absorptance as a
function of intrinsic material solar absorptance for flat and
finned geometries at the meso scale. As can be seen in FIG. 18, the
effective solar absorptance (or light trapping) for the finned
surface is increased relative to a flat surface, and the increase
is more pronounced at lower intrinsic material solar absorptance
values.
[0073] The invention being thus described, it will be obvious that
the same may be varied in many ways. Such variations are not to be
regarded as a departure from the spirit and scope of the invention,
and all such modifications as would be obvious to one skilled in
the art are intended to be included within the scope of the
appended claims. It is intended that the scope of the invention be
defined by the claims appended hereto. The entire disclosures of
all references, applications, patents and publications cited above
are hereby incorporated by reference.
[0074] In addition, many modifications may be made to adapt a
particular situation or material to the teachings of the disclosure
without departing from the essential scope thereof. Therefore, it
is intended that the disclosure not be limited to the particular
embodiment disclosed as the best mode contemplated for carrying out
this disclosure, but that the disclosure will include all
embodiments falling within the scope of the appended claims.
* * * * *