US20100294266A1

US20100294266A1 - Concentrated solar thermal energy collection device

Info

Publication number: US20100294266A1
Application number: US12/471,074
Authority: US
Inventors: Tak Pui Jackson FUNG
Original assignee: Individual
Current assignee: Renewable Energy Group Ltd
Priority date: 2009-05-22
Filing date: 2009-05-22
Publication date: 2010-11-25

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.

Description

BACKGROUND

1. Field of the Invention
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.
2. Related Arts
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.
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.
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.
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.
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

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.
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.
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×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×n array of mirrors; a heat absorption tube disposed along a longitudinal axis passing through the focal area of the m×n array of mirrors and parallel to the support frame; one or more support members to support the heat absorption tube above the m×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×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.
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×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×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×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

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.

FIG. 1A-1B illustrate two different views of a concentrated solar collector module, according to an embodiment of the present invention.

FIG. 2A illustrates a tiltable mirror array, according to an embodiment of the present invention.

FIGS. 2B-2D illustrate positional adjustments of the tiltable mirrors, according to embodiments of the present invention.

FIGS. 3A-3B illustrate an embodiment of the concentrated solar collector module using a sealed heat tube.

FIG. 4 illustrates seasonal adjustment of an entire concentrated solar collector module, according to an embodiment of the present invention.

FIGS. 5-7 illustrate various example array configurations using individual concentrated solar collector modules, according to embodiments of the present invention.

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.

FIGS. 9-11 illustrate various applications of concentrated solar collector systems, according to embodiments of the present invention.

DETAILED DESCRIPTION

Overview

On a clear sunny day, 1000 watt/m²solar 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.
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.
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.
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.
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.
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.
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.
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×n array in m number of rows and n number of columns. Area of each mirror 102 is ‘a×b’, and area of the entire frame defining the footprint of the module is ‘c×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×b’=0.09 m²in area, and the overall footprint of the module 100 is ‘c×d’=3.6 m², 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° C. to 100° C.
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.
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.
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
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.
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.
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° with respect to a horizontal axis. Orienting the entire module may relax the requirement of tilting the individual mirrors 102.
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.
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 4×1 array configurations, i.e., 4 rows of modules are arranged in a single column, and FIG. 7 shows a 4×3 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 1×3 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
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.
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 5×1 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.
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.
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.
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

Some example systems employing concentrated solar collectors are discussed below.
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° C. to 100° C. The concentrated solar collector can achieve these temperature range even at low sun ray.
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.
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.
The desalination process may start as low as 60° C. as the sea water starts to boil at low pressure such as 0.1 bar. However, if the temperature is above 105° C., the distilled water is more potable, and safer for drinking, etc.
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×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° C. and pressure at 100 bar and a mass flow rate of 1 kg/sec.
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.

Claims

1. A solar thermal energy collector device, comprising at least one collector module, the collector module including:

an m×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×n array of mirrors;

a heat absorption tube disposed along a longitudinal axis passing through the focal area of the m×n array of mirrors and parallel to the support frame;

one or more support members to support the heat absorption tube above the m×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×n array of mirrors; and

transparent panels positioned to protect the m×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×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×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×n array of mirrors; and

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.