CONCENTRATED SOLAR THERMAL ENERGY COLLECTION DEVICE
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.
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.
SUMMARYThe 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.
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.
On a clear sunny day, 1000 watt/m2 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.
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.
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.
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
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
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.
Collector Module with Fluid Circulation Conduit at the Focal Line
As shown
As shown in
Though in
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
Some example systems employing concentrated solar collectors are discussed below.
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
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.
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
- transparent panels positioned to protect the m×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.
Type: Application
Filed: May 22, 2009
Publication Date: Nov 25, 2010
Inventor: Tak Pui Jackson FUNG (Hong Kong)
Application Number: 12/471,074