U.S. patent application number 12/471074 was filed with the patent office on 2010-11-25 for concentrated solar thermal energy collection device.
Invention is credited to Tak Pui Jackson FUNG.
Application Number | 20100294266 12/471074 |
Document ID | / |
Family ID | 43123713 |
Filed Date | 2010-11-25 |
United States Patent
Application |
20100294266 |
Kind Code |
A1 |
FUNG; Tak Pui Jackson |
November 25, 2010 |
CONCENTRATED SOLAR THERMAL ENERGY COLLECTION DEVICE
Abstract
This patent application discloses structure and use of
concentrated solar thermal energy collector modules, installed
individually, or in an array configuration. Because of the modular
design, the individual collector modules are easier to manufacture,
transport, and install. Systems of varying scale and varying
thermal output may be built by custom arrangement of individual
collector modules. Each module comprises a tiltable mirror array, a
support frame for the mirror array, a heat absorption tube at a
focal point of the mirror array, a parabolic mirror concentrator
above the heat absorption tube, and two transparent protective
panels coupled between the mirror concentrator with the support
frame. The heat absorption tube may be a sealed heat tube, or a
fluid circulation conduit. The mirrors are configured to be
positionally adjusted to improve focusing of thermal energy and/or
to track the changing position of the sun.
Inventors: |
FUNG; Tak Pui Jackson; (Hong
Kong, HK) |
Correspondence
Address: |
NIXON PEABODY, LLP
401 9TH STREET, NW, SUITE 900
WASHINGTON
DC
20004-2128
US
|
Family ID: |
43123713 |
Appl. No.: |
12/471074 |
Filed: |
May 22, 2009 |
Current U.S.
Class: |
126/688 |
Current CPC
Class: |
F22B 1/006 20130101;
Y02B 10/20 20130101; F24S 23/79 20180501; Y02E 10/45 20130101; F24S
23/77 20180501; Y02E 10/40 20130101; F24S 23/74 20180501 |
Class at
Publication: |
126/688 |
International
Class: |
F24J 2/10 20060101
F24J002/10 |
Claims
1. A solar thermal energy collector device, comprising at least one
collector module, the collector module including: an m.times.n
array of mirrors receiving and reflecting solar light incident on
them, wherein the array of mirrors is configured to focus reflected
solar light at a focal area vertically above a center point of the
array; a support frame supporting the m.times.n array of mirrors; a
heat absorption tube disposed along a longitudinal axis passing
through the focal area of the m.times.n array of mirrors and
parallel to the support frame; one or more support members to
support the heat absorption tube above the m.times.n array of
mirrors; a parabolic mirror concentrator in the shape of a hollow
partial cylinder disposed lengthwise parallel to and above the heat
absorption tube, such that a curved reflective inner surface of the
parabolic mirror concentrator faces the heat absorption tube and
the m.times.n array of mirrors; and transparent panels positioned
to protect the m.times.n array of mirrors from particulate
matters.
2. The device of claim 1, wherein the heat absorption tube
comprises a sealed heat pipe containing a heat transfer fluid
trapped therein, and enclosed by an evacuated glass tube.
3. The device of claim 1, wherein the device further comprises a
thermally insulated fluid circulation conduit coupled to one end of
the heat absorption tube forming a junction, wherein the fluid
circulation conduit directs relatively colder fluid towards the
junction and transports relatively warmer fluid away from the
junction.
4. The device of claim 3, wherein the device further comprises a
connector disposed at the junction providing mechanical and thermal
contact between the heat absorption tube and the fluid circulation
conduit.
5. The device of claim 3, wherein the fluid circulation conduit is
coupled to a fluid inlet pipe at a first end and a fluid outlet
pipe at a second end opposite to the first end.
6. The device of claim 5, wherein a linear array of one or more
individual collector modules is coupled to the fluid circulation
conduit.
7. The device in claim 6, wherein the linear array of one or more
individual collector modules is repeated a number of times in
parallel, each linear array having a corresponding fluid
circulation conduit, spanning between the fluid inlet pipe and the
fluid outlet pipe, creating a rectangular array of individual
collector modules.
8. The device of claim 1, wherein the panels are made of tempered
glass.
9. The device of claim 1, wherein inner surfaces of the panels are
coated with anti-reflection coating material to prevent solar light
reflected by the array of mirrors from escaping the collector
module.
10. The device of claim 1, wherein the reflective inner surface of
the parabolic mirror concentrator directs reflected solar light
escaping the heat absorption tube back to the heat absorption
tube.
11. The device of claim 1, wherein each of the mirrors are capable
of being positionally adjusted in one or more directions to
optimize collection of solar light as the position of sun changes
with respect to the mirror.
12. The device of claim 11, wherein the positional adjustment of
the mirrors includes seasonal adjustment based on the sun's
position varying between the winter solstice and the summer
solstice.
13. The device of claim 11, wherein the positional adjustment of
the mirrors includes daily adjustment based on the sun's position
varying between sunrise and sunset.
14. The device of claim 11, wherein the positional adjustment of
the mirrors includes providing a reference setting based on the
latitude of an installation site.
15. The device of claim 1, wherein the entire collector module is
positionally adjusted based on the sun's position varying between
the winter solstice and the summer solstice.
16. A solar thermal energy collector system mounted on a wall of a
structure, comprising: a fluid circulation conduit running parallel
to the wall, wherein relatively colder fluid comes in through a
bottom end of the fluid circulation conduit, and relatively warmer
fluid comes out from the top of the fluid circulation conduit; a
plurality of individual collector modules stacked in a linear array
configuration along the wall, such that the fluid circulation
conduit is disposed along a common focal axis of all the collector
modules, each collector module comprising: an m.times.n array of
mirrors receiving and reflecting solar light incident on them,
wherein the array of mirrors is configured to focus reflected solar
light along the focal axis vertically above and parallel to a
longitudinal center line of the array of mirrors, thereby heating
up the fluid circulated within the fluid circulation conduit; a
support frame supporting the m.times.n array of mirrors; a
parabolic mirror concentrator in the shape of a hollow partial
cylinder disposed lengthwise parallel to and above the fluid
circulation conduit, such that a curved reflective inner surface of
the parabolic mirror concentrator faces the fluid circulation
conduit and the m.times.n array of mirrors; and transparent panels
positioned to protect the m.times.n array of mirrors from
particulate matters.
17. The system of claim 16, wherein the linear array individual
collector modules is repeated a number of times in parallel, each
linear array having a corresponding fluid circulation conduit
coupled to it, creating a rectangular array of individual collector
modules.
18. The device of claim 16, wherein inner surfaces of the panels
are coated with anti-reflection coating material to prevent solar
light reflected by the array of mirrors from escaping the collector
module.
19. The device of claim 16, wherein the first plate and the second
plate in each collector module are made of tempered glass.
20. The device of claim 16, wherein each of the mirrors are capable
of being positionally adjusted in one or more directions to
optimize collection of solar light as the position of sun changes
with respect to the mirror.
21. The device of claim 20, wherein the positional adjustment of
the mirrors includes seasonal adjustment based on the sun's
position varying between the winter solstice and the summer
solstice.
22. The device of claim 20, wherein the positional adjustment of
the mirrors includes daily adjustment based on the sun's position
varying between sunrise and sunset.
23. The device of claim 20, wherein the positional adjustment of
the mirrors includes proving a reference setting based on the
latitude of an installation site.
Description
BACKGROUND
[0001] 1. Field of the Invention
[0002] This invention relates generally to solar thermal energy
collector, and more specifically, to modular solar collector
devices with movable mirrors for concentrating solar energy to heat
up a fluid.
[0003] 2. Related Arts
[0004] Solar energy is widely recognized as a valuable
environment-friendly renewable energy source. Solar energy is
harnessed in various ways. For example, solar optical energy may be
converted into electrical energy by using photovoltaic solar cells.
Alternatively, solar thermal energy may be used by collecting
sunlight as a thermal energy source. The collected solar thermal
energy may be used to directly or indirectly heat up a target, or
to generate vapor to run a turbine that generates electricity.
Conventionally, harnessing solar thermal energy is recognized as a
relatively simpler and cheaper technology than using photovoltaic
cells.
[0005] Parabolic trough mirrors/reflectors have been used to
concentrate solar thermal energy into a relatively smaller focal
area in order to increase energy collection efficiency. However,
the size of a typical parabolic trough mirror may still be quite
large. Manufacture and transport of oversized parabolic trough
mirrors is likely to be cost-prohibitive for smaller-scale
high-volume use, such as, household use. Additionally, a rigid
parabolic reflective surface may optimally collect solar energy
only for a particular position of the sun, unless the reflective
surface is mechanically driven to track the changing position of
the sun.
[0006] Instead of using one continuous parabolic reflective
surface, some existing systems divide the reflective surface into
individually tiltable mirrors to optimize collection efficiency for
a particular position of the sun, and/or to track the sun's
changing position. Individual planar mirrors can be installed as a
radial array to "focus" sunrays on a solar tower. However, even the
individual mirrors have relatively large dimension, and the height
of the solar tower is usually quite high, as the designs have been
developed for large-scale installations, such as solar power plants
or vast solar fields.
[0007] Smaller solar thermal energy collectors, such as, flat-plate
collectors with an absorbing base, and a plurality of evacuated
glass tubes have been used for heating up household water supply,
swimming pools etc. However, the collection efficiency of the
conventional solar thermal collectors is not very high.
[0008] Therefore, what is needed is a solar thermal energy
collection device that is scalable, modular in design for ease of
manufacture, transport, and installation, with each module having a
reasonable form factor, while being efficient in collecting and
concentrating solar thermal energy and adjusting to the changing
position of the sun.
SUMMARY
[0009] The following summary is included in order to provide a
basic understanding of some aspects and features of the invention.
This summary is not an extensive overview of the invention and as
such it is not intended to particularly identify key or critical
elements of the invention or to delineate the scope of the
invention. Its sole purpose is to present some concepts of the
invention in a simplified form as a prelude to the more detailed
description that is presented below.
[0010] This patent application discloses structure and use of
concentrated solar thermal energy collector modules, installed
individually, or in an array configuration. Because of the modular
design, the individual collector modules are easier to manufacture,
transport, and install. Systems of varying scale and varying
thermal output may be built by custom arrangement of individual
collector modules. In various embodiments, an array of planar
mirrors is configured to be positionally adjusted individually to
improve focusing of thermal energy and/or to track the changing
position of the sun.
[0011] According to certain aspects of the invention, a solar
thermal energy collector device comprising at least one collector
module is described. Each collector module includes: an m.times.n
array of mirrors receiving and reflecting solar light incident on
them, wherein the array of mirrors is configured to focus reflected
solar light at a focal area vertically above a center point of the
array; a support frame supporting the m.times.n array of mirrors; a
heat absorption tube disposed along a longitudinal axis passing
through the focal area of the m.times.n array of mirrors and
parallel to the support frame; one or more support members to
support the heat absorption tube above the m.times.n array of
mirrors; a parabolic mirror concentrator in the shape of a hollow
partial cylinder disposed lengthwise parallel to and above the heat
absorption tube, such that a curved reflective inner surface of the
parabolic mirror concentrator faces the heat absorption tube and
the m.times.n array of mirrors; and panels made of a material
transparent to the solar light coupled between the parabolic mirror
concentrator and the support frame.
[0012] According to another aspect of the invention, a solar
thermal energy collector system is described, that is mounted on a
wall of a structure. A fluid circulation conduit runs parallel to
the wall, wherein relatively colder fluid comes in through a bottom
end of the fluid circulation conduit, and relatively warmer fluid
comes out from the top of the fluid circulation conduit. A
plurality of individual collector modules are stacked in a linear
array configuration along the wall, such that the fluid circulation
conduit is disposed along a common focal axis of all the collector
modules. Each collector module comprises: an m.times.n array of
mirrors receiving and reflecting solar light incident on them,
wherein the array of mirrors is configured to focus reflected solar
light along the focal axis vertically above and parallel to a
longitudinal center line of the array of mirrors, thereby heating
up the fluid circulated within the fluid circulation conduit; a
support frame supporting the m.times.n array of mirrors; a
parabolic mirror concentrator in the shape of a hollow partial
cylinder disposed lengthwise parallel to and above the fluid
circulation conduit, such that a curved reflective inner surface of
the parabolic mirror concentrator faces the fluid circulation
conduit and the m.times.n array of mirrors; and panels made of a
material transparent to the solar light coupled between the mirror
concentrator and the support frame.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The accompanying drawings, which are incorporated in and
constitute a part of this specification, exemplify the embodiments
of the present invention and, together with the description, serve
to explain and illustrate principles of the invention. The drawings
are intended to illustrate major features of the exemplary
embodiments in a diagrammatic manner. The drawings are not intended
to depict every feature of actual embodiments nor relative
dimensions of the depicted elements, and are not drawn to
scale.
[0014] FIG. 1A-1B illustrate two different views of a concentrated
solar collector module, according to an embodiment of the present
invention.
[0015] FIG. 2A illustrates a tiltable mirror array, according to an
embodiment of the present invention.
[0016] FIGS. 2B-2D illustrate positional adjustments of the
tiltable mirrors, according to embodiments of the present
invention.
[0017] FIGS. 3A-3B illustrate an embodiment of the concentrated
solar collector module using a sealed heat tube.
[0018] FIG. 4 illustrates seasonal adjustment of an entire
concentrated solar collector module, according to an embodiment of
the present invention.
[0019] FIGS. 5-7 illustrate various example array configurations
using individual concentrated solar collector modules, according to
embodiments of the present invention.
[0020] FIGS. 8A-C illustrate another example configuration of the
present invention, where a fluid circulating conduit passes through
a focal line of a plurality of concentrated solar collectors.
[0021] FIGS. 9-11 illustrate various applications of concentrated
solar collector systems, according to embodiments of the present
invention.
DETAILED DESCRIPTION
Overview
[0022] On a clear sunny day, 1000 watt/m.sup.2 solar energy is
estimated to reach the earth. With a properly designed solar
collector, it is possible to harness solar energy at efficiencies
as high as 70% or more. Solar collectors are optimally designed to
concentrate solar energy to increase collection efficiency. A
concentrated solar collector may be a single device module, or a
bunch of device modules arranged in a desired configuration.
Collected solar thermal energy can be used to raise the temperature
of water or other fluids. When enough number of concentrated solar
collector device modules are installed in a proper configuration,
the cumulative thermal energy may be sufficient to generate steam
or other gaseous vapors that can run a turbine to generate
electricity.
[0023] Potential applications of the embodiments of the present
invention may be in the fields of heating, air conditioning,
refrigeration, hot fluid-based environmental purification and
germ-killing, sea-water desalination, electricity generation (e.g.,
steam turbine) etc. As the embodiments of the present invention are
scalable, they can be modified for domestic, commercial, or
industrial applications.
[0024] FIG. 1A illustrates the main components of an individual
concentrated solar collector device module 100, according to an
embodiment of the present invention, shown in a perspective view.
Module 100 comprises a planar mirror array 103, a support frame 104
at the base of the module 100 housing and supporting the planar
mirror array 103, a reflective parabolic mirror concentrator 108 in
the shape of a partial cylinder facing down towards the planar
mirror array 103, a heat absorption tube 110 containing a fluid
therein, installed at a focal area of the planar mirror array 103,
and two transparent protective panels 106A and 106B, that are
coupled between the parabolic mirror concentrator 108 and the
support frame 104. Each of the planar mirrors 102 in the planar
mirror array 103 are mechanically coupled to the support frame 104
via connecting structures 115 spanning longitudinally, and
connecting structures 113, spanning laterally. Each planar mirror
102 can be individually tilted to a desired angle in one or more
directions by a tilt control mechanism 111. Details of the tilt
control mechanism 111 are not limiting to the embodiments of the
invention, and are apparent to people skilled in the art. In an
example embodiment, tilt control mechanism may include, among other
components, mechanical parts, such as, a plurality of cams
connected by a chain, and electronic parts, such as a timer to
track the sun's position during the course of a day. The mirror
tilting concept is further elaborated with respect to FIG. 2D.
[0025] FIG. 1B shows a front view of the module 100, showing that
the heat absorption tube 110 is disposed at a vertical distance `h`
from the plane of the untilted mirrors 102. Reflected sunrays from
the planar mirrors 102 are focused (as shown in FIG. 2D) onto the
heat absorption tube 110. Preferably, heat absorption tube 110 is
also disposed along the focal line of the parabolic mirror
concentrator 108. Although not shown specifically in FIGS. 1A-1B,
heat absorption tube 110 may be mechanically coupled to one or more
parts of module 100 by mechanical structures, such as vertical or
horizontal support rods. One such support structure is shown in
subsequent FIGS. 3A-3B. Example configurations of the heat
absorption tube 110 include, but, are not limited to, a sealed heat
tube (as shown in FIG. 3A-7), and, an open-ended fluid circulation
conduit with thermally conductive walls, through which a fluid
flows (as shown in FIG. 8A-C). Mirrors 102 are shown to be raised
at a finite height above the support frame 104, but the separation
`y` is shown in an exaggerated manner to clarify that the mirrors
are pivotally mounted and are configured to be actuated in one or
more directions.
[0026] Support frame 104 may be rectangular, encircling the mirror
array 103. Edges of the support frame may be parallel to the edges
of the individual planar mirrors 102. Other shapes of the support
frame 104 are possible too. Support frame 104 may be made of
stainless steel, though other materials can be used. Support frame
104 and longitudinal and lateral connecting structures 115 and 113
may provide mechanical and/or thermal stress relief to the mirror
array 103. Support frame 104 may include a backside (not
specifically shown) to protect the backside of the mirror array 103
from water, dust, mechanical damage due to friction etc.
Electrically conductive portions of a support frame 104 and
connecting structures 113 and 115 may help in bringing control
signals from tilt control mechanism 111 to the individual mirrors
102.
[0027] Two transparent panels 106A and 106B, disposed between the
parabolic mirror concentrator 108 and the support frame 104 protect
the mirror array 103 and the heat absorption tube 110 partially
from wind, dust, rain, snow, mechanical damages etc. The panels
106A and 106B may also provide structural stability to the module
100 if the panels are made of rigid material. There may be a load
bearing frame (not shown) around the panels for further structural
stability. The panels 106A and 1068 may be used to secure the
parabolic mirror concentrator 108 at the desired height above the
mirror array 103. The material of the transparent panels 106A and
1068 should be non-reflective to maximize incident solar energy on
the mirrors 102. Reflective coatings (not shown) may be applied on
the inner surfaces of the panels 106A and 1068 so that incident
sunlight does not escape the module 100. Tempered glass or other
transparent polymers may be used as the material for the panels
106A and 1068. Panels 106A and 1068 also make cleaning and
maintenance of the module 100 easier. Most of the time it is
sufficient to clean off the outside surfaces of the panels 106A and
1068, rather than cleaning the mirror array 103. Persons skilled in
art will understand that more than two protective panels may be
included in the design of a module.
[0028] Parabolic mirror concentrator 108 is in the shape of a
partial cylinder whose cross section is parabolic. The parabolic
mirror concentrator 108 traps sunrays not absorbed by and/or
deflected by the heat absorption tube 110. Inner curved surface of
the parabolic mirror concentrator 108 is reflective. The heat
absorption tube 110 is preferably disposed along the longitudinal
focal axis of the cylindrical surface of the mirror concentrator.
Sunrays reflected back from the mirror concentrator 108 to the heat
absorption tube 110 increases thermal energy collection efficiency
of module 100. Mirror concentrator 108 may be made of aluminum or
other reflective materials. The heat absorption tube 110 may be
mechanically suspended from the mirror concentrator 108 with rigid
rods as opposed to being coupled to the support frame 104. Along
with the panels 106A and 106B, the mirror concentrator 108 also
provide protection to the heat absorption tube 110 and mirror array
103.
[0029] FIG. 2A shows a top view of the planar mirror array 103,
including the support frame 104, but excluding the longitudinal and
lateral connecting structures 115 and 113 for the sake of clarity.
Individual planar mirrors 102 are arranged in a rectangular
m.times.n array in m number of rows and n number of columns. Area
of each mirror 102 is `a.times.b`, and area of the entire frame
defining the footprint of the module is `c.times.d`. Number of
array elements, i.e. m and n, and dimensions a, b, c, and d are
chosen to optimize the form factor of the module 100 to achieve a
targeted energy collection efficiency. In the example embodiment
shown in FIG. 2A, m=5 and n=5, i.e. a total of 25 planar mirrors
102 are included. Each planar mirror 102 may be a 300 mm square,
i.e. `a.times.b`=0.09 m.sup.2 in area, and the overall footprint of
the module 100 is `c.times.d`=3.6 m.sup.2, where c=2000 mm and
d=1800 mm. Persons skilled in the art will understand that these
example numbers and dimensions are for illustrative purposes only,
and do not limit the inventive concepts. Calculations by the
inventors have shown that an array 103 as shown in FIG. 2A can
collect 2520 watts of solar thermal energy, which is enough to
raise the temperature of 25 liters of water from 15.degree. C. to
100.degree. C.
[0030] FIG. 2B and 2C show in perspective views how the planar
mirrors 102 can be individually tilted in multiple directions in
order to tightly focus reflected sunlight at a focal spot 210 (FIG.
2B) or along a focal line 211 (FIG. 2C) at a height `h` vertically
above a center point 203 of the array 103. The focal spot 210 or
focal line 211 may have a finite area over which the collected
solar thermal energy is distributed. In case of FIG. 2C, mirrors
along a single column are all tilted at the same angle, while in
case of FIG. 2B, each mirror is tilted at a different angle.
[0031] FIG. 2D shows front views of the module 100 at different
times of a day to illustrate how the mirror tilting is adjusted to
track the changing position of the sun during the course of a day
between sunrise and sunset. As seen in FIG. 2D, sunrays fall on the
module 100 at various angles at various times of the day. By
tilting the mirrors 102 appropriately, most of the incident sunrays
can be focused onto the heat absorption tube 110.
[0032] Positional adjustment of the mirrors is not limited to
tracking the position of sun during a day. For example, mirrors 102
can be seasonally adjusted based on the sun's position varying
between the winter solstice and the summer solstice. The seasonal
adjustment can be done on a monthly basis or at other arbitrary
time intervals. In one example, seasonal adjustment can be done by
tilting the mirrors 102 in the north-south direction, while daily
adjustment can be done by tilting the mirrors in the east-west
direction. Another possibility is to provide a reference tilt
setting for the mirrors based on the latitude of the installation
site. Persons skilled in the art will appreciate that one or more
of the potential positional adjustment schemes may be adopted in
order to achieve the desired thermal energy collection
efficiency.
Collector Module with Sealed Heat Tube
[0033] FIG. 3A shows a perspective view from the side, and FIG. 3B
shows the a perspective view from the front of an example
embodiment of the present invention, where a concentrated solar
collector (CSC) module 300 is shown to include a sealed heat tube
310, connected to a fluid circulation conduit 309. Components of
module 300 that are identical to the components of module 100 shown
in FIG. 1A are indicated by the identical reference numbers. In the
example embodiment shown in FIG. 3A, the sealed heat tube 310
comprises an evacuated glass heat tube surrounding a copper heat
pipe. This configuration of sealed heat tube 310 is known in the
art. Outer diameter of the evacuated glass heat tube may be about
58 mm, while the outer diameter of the copper heat pipe may be 25
mm. Other dimensions are possible too. The evacuated glass heat
tube is configured to prevent thermal energy loss from the heat
pipe by providing thermal insulation. A heat transfer fluid trapped
inside the heat pipe helps in transferring the thermal energy to
the heat pipe. Fluid (e.g., water) circulating inside the fluid
circulation conduit 309 does not get inside the heat absorption
tube 310, as the ends of the heat absorption tube 310 are sealed.
Instead, thermal energy is transferred to the circulating fluid
from the heat absorption tube 310 through a junction 312. A
connector (not specifically shown) at the junction 312 provides
good mechanical and thermal contact between the heat absorption
tube 310 and the fluid circulation conduit 309. Support bars 314A
and 314B mechanically support heat absorption tube 310 to position
the heat absorption tube 310 at the focal point of the mirror array
103.
[0034] Fluid circulation conduit 309 may be a thermally insulated
pipe. The pipe may be made of copper or other materials. It is
recommended to use high-performance thermal insulation material
around the pipe to prevent heat loss. Diameter of the pipe may be
50 mm. Materials, shapes and dimensions discussed here are for
illustrative purposes, and are not restrictive. Fluid circulation
conduit 309 brings in relatively colder fluid towards the CSC
module 300, and carries relatively warmer fluid away from the CSC
module 300, as the temperature of the fluid increases by absorbing
heat from the sealed heat tube 310. Fluid circulation conduit 309
may be a part of a larger fluid circulation/recirculation circuit,
as will be described later in the specification with respect to
FIGS. 5-7.
[0035] FIG. 4 shows that the module 300 as a whole can be oriented
at an angle with respect to the fluid circulation conduit 309 in
order to adjust to the sun's position in winter solstice and/or
summer solstice. In the example shown in FIG. 4, the angle of
orientation is 21.degree. with respect to a horizontal axis.
Orienting the entire module may relax the requirement of tilting
the individual mirrors 102.
[0036] Individual concentrated solar collector modules 300 may be
arranged in a variety of configurations to achieve a desired degree
of temperature conditioning of circulated fluid, or to deliver a
required amount of total thermal energy to a local or remote
target. FIG. 5 shows a linear array 500 of concentrated solar
collector modules. Though in the example shown in FIG. 5, four
modules 300A-D are shown, any number of modules may be used. Each
of the modules 300A-D has a corresponding heat absorption tube
310A-D coupled to a corresponding portion 309A-D of a common fluid
circulation conduit 509.
[0037] FIGS. 6 and 7 show two more example configurations of a
solar energy collection system built by arranging individual
concentrated solar collector modules 300. FIG. 6 shows a 4.times.1
array configurations, i.e., 4 rows of modules are arranged in a
single column, and FIG. 7 shows a 4.times.3 array configurations,
i.e., 4 rows of modules are arranged, each row having three
columns. In FIG. 6, each of the fluid circulation conduits 309A-D
is coupled to a fluid inlet pipe 742 and a fluid outlet pipe 748.
Relatively colder fluid goes into inlet port 740, and relatively
warmer fluid comes out of outlet port 750. It is possible to
channel out fluids of different degrees of temperature from
intermediate points 746A-D along fluid outlet pipe 748. In FIG. 7,
each 1.times.3 linear array of modules shares a corresponding
common fluid circulation conduit 509A-D. Each of the common fluid
circulation conduits 509A-D is coupled to fluid inlet pipe 742 and
fluid outlet pipe 748. similar to FIG. 6, It is possible to channel
out fluids of different degrees of temperature from intermediate
points 746A-D along fluid outlet pipe 748. Also, total number of
rows and columns, and/or the number of individual concentrated
solar collector modules 300 in each row or column may be varied.
Persons skilled in the art will appreciate that the modular design
of the system is well-suited for providing flexibility in tuning
the temperature of the circulating fluid and/or tuning the
cumulative thermal energy transferred to the circulating fluid.
Collector Module with Fluid Circulation Conduit at the Focal
Line
[0038] FIGS. 8A-C show an embodiment of the present invention,
where instead of using a separate sealed heat tube 310 in each
concentrated solar collector module 100, a fluid circulation
conduit 810 itself is used as the heat absorption tube 110 disposed
along a focal line of a mirror array 103 (not specifically labeled
in FIG. 8A-C, but labeled in FIG. 1A). In this embodiment, the
fluid circulating inside the fluid circulating conduit 810 directly
gets heated by solar light reflected by the mirror array 103,
rather than having the thermal energy transferred to the
circulating fluid from a sealed heat tube, such as the heat tube
310.
[0039] As shown FIGS. 8A-C, in an example embodiment, a number of
individual CSC modules 100A-E are stacked vertically above the
ground level 802 in a linear 5.times.1 array along a south-facing
wall 862 of a building 860. FIG. 8A shows a combined side and
frontal perspective view, FIG. 8B shows a side view, and FIG. 8C
shows a front view of the linear array. To secure the position of
the fluid circulation conduit 810 with respect to the respective
mirror arrays 103 of the individual concentrated solar collector
modules 100A-E, mechanical support structures (such as a supporting
bar 814) may be included in the individual concentrated solar
collector modules 100. Alternatively, the fluid circulation conduit
810 can be supported by mechanical support structures projecting
from the wall 862 at suitable locations.
[0040] As shown in FIG. 8B, the angle at which the sunrays approach
the individual concentrated solar collector modules 100A-E varies
seasonally. The mirrors are positionally adjusted to track the
seasonal variation of the sun's position. Additionally, as
discussed before, the mirrors may be positionally adjusted to track
the sun's position at different times of a day. It is also possible
to provide a reference mirror setting depending on the latitude of
the building location.
[0041] Though in FIGS. 8A-C, just one linear array is shown,
persons skilled in the art will appreciate that the linear array
may be repeated in parallel to create a bigger two-dimensional
array, each array having a corresponding fluid circulation conduit
running through the individual modules of a linear array.
[0042] Relatively colder fluid (e.g., water) goes into the bottom
end of the fluid circulation conduit 810, collects concentrated
solar thermal energy from the modules 100A-E, and relatively warmer
fluid comes out from the top end of the fluid circulation conduit
810. This system may be useful, for example, for household water
heating. As discussed with respect to FIGS. 5-7, the modular design
of the system shown in FIGS. 8A-C is also well-suited for providing
flexibility in tuning the temperature of the circulating fluid
and/or tuning the cumulative thermal energy transferred to the
circulating fluid.
Example Circulation Systems
[0043] Some example systems employing concentrated solar collectors
are discussed below.
[0044] FIG. 9 shows an example absorption chiller system. As shown
in FIG. 9, an absorption chiller system 900 is used to provide a
cold fluid for various applications, such as, space cooling, air
conditioning, refrigeration, ice-making, cold storage etc. A
heat-source fluid (e.g., hot water) is used as a source of heat
that evaporates a coolant inside the absorption chiller chamber
965. The coolant may be chilled water or other chilled fluids. The
heat-source fluid at a relatively lower temperature goes into the
fluid inlet pipe 742 at the inlet port 740, collects concentrated
solar thermal energy from the modules 300A-D, and flows into a heat
source fluid inlet pipe 960 coupled to the outlet port 750 of the
fluid outlet pipe 748. The hot fluid temperature requirement is
between 88.degree. C. to 100.degree. C. The concentrated solar
collector can achieve these temperature range even at low sun
ray.
[0045] The hot heat-source fluid then flows into a heat exchanger
structure 967 housed inside the absorption chiller chamber 965,
where heat is transferred to the coolant. Once the hot heat-source
fluid loses its heat inside the absorption chiller chamber 965, it
comes out through the heat source outlet pipe 970, and goes back
into the modules 300A-D by the driving force of a hot water pump
980. Though not shown specifically in the simplified schematic of
FIG. 9, the absorption chiller chamber 965 comprises a number of
sub-chambers within it that may contain a refrigerant with a low
boiling point. During the heat exchange process, chilled water
absorbs heat from the heat-source fluid, and gets evaporated into a
sub-chamber and eventually, condenses through a cooling process.
The refrigerant gets concentrated under pressure and goes in
another sub-chamber where the pressure is reduced. The refrigerant
then flows into yet another chamber, where the refrigerant absorbs
the heat from the warmer chilled water and starts boiling as vapor.
The refrigerant boils near the chilled water outlet 910. The
boiling refrigerant in vapor form returns to the absorption chiller
chamber 965 where the heat exchange and evaporating process
continues. The chilled fluid is used to drive fan coils 920 to
generate cool air. The fluid absorbs heat emanating from the cooled
objects, and flows back to the chilled water inlet 962 by the
driving force of the chilled water pump 930.
[0046] FIG. 10 shows an exemplary desalination system 1000 that
uses solar-energy-generated steam as the thermal power source. The
solar-heated fluid flows into the heat source inlet pipe 760
leading to a heat exchanger chamber 1072, inside which a second
fluid (e.g. sea water) is evaporated. Filtered seawater is drawn
into the seawater inlet pipe 1055 by the driving force of the sea
water supply pump 1065. The seawater acts as a coolant for the
distilled steam. The seawater absorbs heat from the distilled steam
and flows into the heat exchanger chamber 1072 as a warmer fluid
through the condenser outlet 1085. Inside the heat exchanger
chamber 1072, the seawater may turn into distilled steam and rise
to the top, while concentrated salt water remains at the bottom as
it absorbs more heat from the steam generated in the heat exchanger
chamber 1072. The distilled steam then expands and goes into the
condenser 1074 through the condenser inlet pipe 1096, where the
distilled steam may condense due to the cool seawater acting as the
coolant. The condensed distilled water is collected through the
condenser outlet pipe 1095. The concentrated salt water then flows
out of the heat exchanger chamber 1072 through the saltwater outlet
1098.
[0047] The desalination process may start as low as 60.degree. C.
as the sea water starts to boil at low pressure such as 0.1 bar.
However, if the temperature is above 105.degree. C., the distilled
water is more potable, and safer for drinking, etc.
[0048] FIG. 11 shows a concentrated solar collector system 1100
used to drive a steam turbine generator 1160. As described with
respect to FIG. 7, system 1100 has a M.times.N array configuration,
i.e., M rows of modules, each row having N columns, are arranged in
system 1100. Each of the M linear arrays of modules shares a
corresponding common fluid circulation conduit 509A-D. Each of the
common fluid circulation conduits 509A-D is coupled to fluid inlet
pipe 742 and fluid outlet pipe 748. Relatively colder fluid (e.g.,
hot water which is colder than steam) goes into the bottom end of
the fluid circulation conduit 740, collects concentrated solar
thermal energy from the modules 300A-D, and relatively warmer fluid
(e.g., very-high temperature water or steam or vapor) comes out
from the top end of the fluid circulation conduit 750. As the
temperature of the circulating fluid picks up in the collector
modules 300A-D, high pressure steam may be produced at the steam
outlet 750, which is channeled into the steam turbine 1160 which is
coupled to electricity generator 1165. The steam loses significant
pressure and temperature after giving the energy to the steam
turbine, and flows into the condenser/heat exchanger chamber 1170.
The steam condenses into hot water after passing through the
condenser/heat exchanger chamber 1170, as the heat is given off to
the cold fluid circulating in the condenser/heat exchanger chamber
1170. The hot water then circulates back to the solar collector
module inlet 740 by the driving force of the hot water circulation
pump 980. Depending on the size of the electricity generator 1165,
an example steam turbine 1160 may require steam at 350.degree. C.
and pressure at 100 bar and a mass flow rate of 1 kg/sec.
[0049] It should be understood that processes and techniques
described herein are not inherently related to any particular
apparatus and may be implemented by any suitable combination of
components. Further, various types of general purpose devices may
be used in accordance with the teachings described herein. It may
also prove advantageous to construct specialized apparatus to
perform the method steps described herein. The present invention
has been described in relation to particular examples, which are
intended in all respects to be illustrative rather than
restrictive. Those skilled in the art will appreciate that many
different combinations of functional elements will be suitable for
practicing the present invention. Moreover, other implementations
of the invention will be apparent to those skilled in the art from
consideration of the specification and practice of the invention
disclosed herein. Various aspects and/or components of the
described embodiments may be used singly or in any combination in
the relevant arts. It is intended that the specification and
examples be considered as exemplary only, with a true scope and
spirit of the invention being indicated by the following
claims.
* * * * *