Patent application title: Solar Energy Collecting Apparatus
Christopher C. Lovato (Tucson, AZ, US)
IPC8 Class: AF24J208FI
Class name: Solar heat collector with concentrating lens lens support
Publication date: 2010-05-13
Patent application number: 20100116266
A solar energy collecting structure includes a focusing element that is
axially aligned with and fixed in spaced relationship to an associated
concave collector. Each concave collector is fixed at a distance equal to
the focal length of the associated focusing element, for enabling focused
solar energy to be received and collected over an entire temporal
interval--without any need for tracking mechanisms. A solar energy
collecting apparatus may be structured by employing a plurality of the
solar energy collecting structures, in a tightly packed, juxtaposed
(adjacent) relationship, with the focusing elements forming, at least in
significant part, a curved surface of the apparatus for enabling solar
energy to be collected over an expanded temporal interval. This abstract
is provided to comply with rules requiring abstracts, and is submitted
with the intention that it will not be used to interpret or limit the
scope and meaning of the claims.
1. A solar energy collecting apparatus, comprising:a) a support
structure;b) a plurality of focusing elements fixed within openings
formed within the support structure;c) a plurality of solar energy
concave collectors, with each concave collector supported and fixed in
spaced relationship to, and axially aligned with, one of the plurality of
focusing elements, providing one of a plurality of focusing-collecting
pairs, with the concave collector spaced from the focusing element at a
distance equal to the focal length of the focusing element, for enabling
a focusing of incident solar energy upon a concave receiving surface of
the concave collector during an entire temporal interval;d) a thermal
coupling structure for thermally coupling to and transferring solar
energy collected by each concave collector to a heat providing output of
2. The solar energy collecting apparatus in accordance with claim 1, wherein each focusing element includes at least one Fresnel lens.
3. The solar energy collecting apparatus in accordance with claim 2, wherein:a) each of the openings of the support structure being configured to accept, support, and have fixedly installed therein, at least one substantially planar Fresnel lens portion, with the support structure and a first planar surface of the Fresnel lenses providing a curved outer surface of the apparatus; andb) each of the concave collectors is fixed within an interior side of the curved surface, and supported by at least one of:i) the support structure; andii) the thermal coupling structure.
4. The solar energy collecting apparatus in accordance with claim 3, wherein the curved surface is at least one of:a) dome-shaped;b) hemispherical; andc) substantially spherical.
5. The solar energy collecting apparatus in accordance with claim 4, wherein each focusing element is a single Fresnel lens having a monolithic one-piece construction, and wherein the outer surface of the included Fresnel lenses collectively establish at least 90 percent of the surface area of the curved outer surface of the apparatus.
6. The solar energy collecting apparatus in accordance with claim 4, wherein the support structure includes a plurality of coupled elongated members forming, at least in part, each opening into which a Fresnel lens of each focusing element is supported and fixed.
7. The solar energy collecting apparatus in accordance with claim 1, wherein the support structure includes a plurality elongated members forming the openings, with each included opening regularly spaced and structured for supporting one focusing element having at least a Fresnel lens as at least a portion of the focusing element, wherein the shape of the openings includes at least one of:a) triangular shaped openings;b) quadrilateral shaped openings;c) hexagonal shaped openings; andd) honey-comb shaped openings.
8. The solar energy collecting apparatus in accordance with claim 1, wherein the curved surface is dome-shaped with an exhaust vent provided extending upwardly from an upper location of the curved surface.
9. The solar energy collecting apparatus in accordance with claim 1, wherein the temporal interval is in the range of 3 to 6 hours.
10. The solar energy collecting apparatus in accordance with claim 9, wherein the temporal interval varies with at least one of:a) the type of focusing elements employed;b) a latitude of a location at which the solar energy collecting apparatus is located;c) the seasons of the year; andd) natural obstacles that may limit or block the Sun during:i) certain sub-intervals of the temporal interval; andii) certain periods of the year.
11. A fixed solar energy collecting apparatus having no moving portions or parts, the solar energy collecting apparatus comprising:a) a support structure having a plurality of openings and a framework;b) a plurality of focusing elements, which are supported and fixed so as to substantially fill the openings of the support structure, for providing a significant portion of a surface area of a curved outer surface of the solar energy collecting apparatus;c) with each included focusing element capable of focusing useful incident solar energy at a pre-selected fixed focal length for a determinable temporal interval during daylight hours;d) a plurality of solar energy concave collectors, supported and fixed in a one-to-one spaced relationship with the focusing elements, and aligned along a focal plane thereof, such that a solar energy receiving surface of each concave collector is spaced and fixed at a distance equal to the fixed focal length of the focusing element, thereby enabling a focusing of solar energy upon the solar energy receiving surface for receiving and collecting by the concave collector over the entire temporal interval;e) a thermal coupling structure thermally coupled to each concave collector for coupling collected solar heat energy for at least one of:i) storing the heat energy for future use;ii) using the heat energy as a heat source for input to a heat powered mechanism.
12. The fixed solar energy collecting apparatus in accordance with claim 11, wherein each focusing element includes one of:a) a substantially flattened Fresnel lens; andb) a substantially spherical lens.
13. The fixed solar energy collecting apparatus in accordance with claim 11, wherein the focusing elements are provided by Fresnel lenses of a monolithic construction, with one Fresnel lens supported and fixed within each opening of the support structure.
14. The fixed solar energy collecting apparatus in accordance with claim 11, wherein the curved surface is one of:a) dome shaped;b) hemi-spherically shaped; andc) substantially spherically shaped.
15. The fixed solar energy collecting apparatus in accordance with claim 11, wherein each included concave collector is structured with one of:a) a concave black surface for receiving and collecting focused solar energy by converting the solar energy to heat energy; andb) a concave transparent receiving surface for receiving and transmitting focused solar energy to a second surface for collecting the solar energy as heat energy.
16. The fixed solar energy collecting apparatus in accordance with claim 15, wherein each included concave collector having a concave transparent receiving surface, is formed of at least one of:a) sapphire;b) quartz;c) ruby;d) lead crystal glass; ande) water in a glass outer envelope.
17. A fixed solar energy focusing and collecting structure that can focus and collect solar energy over a temporal interval, the focusing and collecting structure comprising:a) a focusing element having associated therewith a pre-selected focal length;b) a concave collector that is supported and fixed in spaced relationship to, and axially aligned with, the focusing element at a distance equal to the pre-selected focal length;c) with a concave curvature of a receiving surface of the concave collector matched to the focal length of the focusing element such that incident solar energy from a range of angles is focused upon and received by the receiving surface of the concave collector over the temporal interval, without the need for tracking and following the movement of source of the solar energy.
18. The focusing and collecting structure in accordance with claim 17, wherein a plurality of the focusing and collecting structures are employed and configured so that a first surface of the focusing elements form a substantial portion of a curved dome-shaped surface such that at least one of the plurality of focusing and collecting structures is positioned for receiving incident solar energy during an extended temporal interval of available daylight hours.
19. The focusing and collecting structure in accordance with claim 17, wherein each focusing element is provided by a Fresnel lens.
20. The focusing and collecting structure in accordance with claim 17, wherein each included concave collector is structured with one of:a) a curved black surface for receiving and collecting focused solar energy by converting the solar energy to heat energy; andb) a concave transparent receiving surface for receiving and transmitting the focused solar energy to a second surface for a converting and collecting of the solar energy as heat energy, with the transparent receiving surface concave collector formed by at least one of:i) sapphire;ii) quartz;iii) ruby;iv) lead crystal glass; andv) a fluid filled glass envelope.
The presently disclosed invention relates most generally to solar energy collecting devices and apparatus. More particularly, the present invention relates to a solar energy collecting arrangement, which employs a plurality of focusing elements that are paired up with properly spaced and aligned concave collectors. Each focusing element and concave collector is fixed within a stationary support structure, for enabling a focusing of solar energy upon each concave collector for a temporal interval lasting at least a number of hours.
As the concerns of global climate change and global warming continue to mount, a clear necessity has arisen to develop and deploy renewable, affordable, and clean alternate energy sources including those based on hydro, geothermal, wind, solar energy, etc. This background section provides a concise general introduction to selected and relevant prior art, and introduces motivations for a plurality of the features of the presently taught and claimed invention. The art discussed herein is not to be considered admitted prior art, and is presented as a starting point to attempt to more clearly discuss and describe important features and structures of the solar energy collecting apparatus of the present invention.
There are a number of prior art teachings wherein solar energy is collected using a variety of structures. A first and well known approach employs what are termed solar collectors, which convert the solar-light energy into electricity or alternately to heat a fluid that is passed through the collectors. Although each type is popular, there are clear limitations to these collectors. First the collectors are far more efficient when facing substantially directly at the Sun. However, the position of the Sun varies with a number of known parameters, such as with the time of day and the time of year. When these types of collectors are mounted using fixed structures, the efficiency and associated duty cycle are clearly not at a maximum for large intervals of daylight hours.
Due to the limitations of fixed mounted collectors, the prior art contains many examples of "tracking structures". Tracking structures are generally electro-mechanical approaches employed to keep the solar collectors of an apparatus substantially directly facing the Sun for as many hours a day, and as many days of the year, as possible. These systems are quite expensive, requiring hinged and pivoting structures along with motors and suitable control systems for sensing and tracking activities. Their cost of ownership is quite high.
Yet another group of prior art teachings attempts to simplify these tracking structures, and in some cases additionally centralize the collecting member(s) of these systems, by employing designs that provide for a tracking of many many mirrors to direct light to one or more centralized `solar receivers`. However, these latter teachings still suffer from a number of issues and limitations. For example, they still require complex and costly sensing and or tracking mechanisms, and additionally require considerable acreage for large scale deployment. Mirrored approaches also require a nearly constant cleaning and upkeep.
Another approach that is known in the art for collecting solar energy is to employ optical lenses to focus a light source to create a concentrated `hot spot`. The well known magnifying glass, with its simple convex lens, has been long used for this purpose--on a clearly very small scale. However, larger versions of such lenses are quite heavy and expensive when scaled up for use in power generation. In addition, such arrangements again require sensing/tracking means for realistic operation over a reasonable number of daylight hours.
Accordingly, what is most desirable in a solar collecting means is a structure and approach that uses fixed or non-tracking structures that are able to be utilized so as to provide reasonable energy collection over a large number of hours a day, and for a large number of days a year. The most preferable approaches would use affordable and scalable methods and structures, requiring minimal maintenance and upkeep. It would further be desirable to provide such a system and approach wherein large acreage is also not required. A number of other characteristics, advantages, and or associated novel features of the present invention, will become clear from the description and figures provided herein. Attention is called to the fact, however, that the drawings are illustrative only. In particular, the embodiments included and described, have been chosen in order to best explain the principles, features, and characteristics of the invention, and its practical application, to thereby enable skilled persons to best utilize the invention and a wide variety of embodiments providable that are based on these principles, features, and characteristics. Accordingly, all equivalent variations possible are contemplated as being part of the invention, limited only by the scope of the appended claims.
SUMMARY OF PREFERRED EMBODIMENTS
In accordance with the present invention, a solar energy collecting structure includes a focusing element supported and fixed in spaced relationship to, and axially aligned with an (associated) solar energy concave collector. This solar energy collecting structure, which may also be termed a `focusing-collecting pair` or `focusing and collecting pair`, functions to enable solar energy incident upon the focusing element to be efficiently focused and collected (upon a collecting black or transparent surface of the concave collector). Importantly, the focusing-collecting pair is specifically structured to enable solar energy to be collected over a temporal interval. Accordingly, each focusing-collecting pair represents a fixed, low cost, and low maintenance structure enabling solar energy to be collected over a temporal interval (e.g., hours) without the need for moving and tracking mechanisms. The collected (solar) heat energy may be stored for later use as a heat source, and or the heat energy may be used immediately as a heat input to any suitable heat powered mechanism. This fixed position solar energy collecting structure, preferably including at least one focusing element and one concave collector, will enable solar energy to be collected over a temporal interval of approximately 3 to 6 hours, at minimum. In addition, based on the structure of the included concave collector, the concave surface of the collector may be provided as a concave black surface for directly receiving and collecting solar light energy. Alternately the concave surface or the collector may be provided by a transparent receiving surface, for receiving and transmitting focused solar energy for subsequent collecting and storage/use.
Further, in order to support a collecting of an increased amount of solar energy, over longer duration temporal intervals (e.g., most of the daylight hours of a typical sunny day), a plurality of the solar energy collecting structures may be provided in tightly packed configurations wherein a plurality of focusing-collecting pairs are placed side-by-side, with an exterior/outer surface of each of the focusing elements closely spaced and collectively forming a significant portion of the area of a curved (outer) surface of a solar energy collecting apparatus. One contemplated preferred embodiment of the solar energy collecting apparatus of the invention may provide a transparent curved surface formed substantially of focusing elements, most preferably fixed in a spherical or dome shaped configuration, wherein 80 to 90% of the curved surface is provided by an outer surface of the focusing elements. It may be noted that the focusing elements may be planar and substantially flattened (as illustrated), or may be more sphere-like in shape (not explicitly shown). When the focusing elements are planar the curved (outer) surface will be relatively flat. When the focusing elements are provided as spheres or balls, the curved surface may be much more textured and possibly described as `bumpy` or nodulous in nature.
To properly support and fix the plurality of focusing elements, the apparatus may include a support structure having a framework establishing the curved surface. Preferably the curved surface includes a plurality of tightly packed openings, into which the focusing elements are supported and fixed. For example, an exemplary focusing element may be provided by, or include, a simple monolithic Fresnel lens. Alternately, other suitable focusing elements may be employed. Importantly, each focusing element, or cluster of focusing elements, would preferably be supported and fixed so as to substantially fill a respective opening of the support structure, and thereby provide a significant portion of the outer surface area of the curved surface of the solar energy collecting apparatus. Specifically, a most preferred solar energy collecting apparatus would provide a curved outer surface wherein at least 80 to 90 percent of the area of the curved surface is provided by a surface of the focusing element material or a clear transparent surface of a cover installed over the focusing elements.
Returning to the focusing elements, each included focusing element is capable of focusing useful incident solar energy at a pre-selected fixed focal length for a determinable temporal interval during daylight hours. Importantly, preferred focusing elements, such as Fresnel lenses, will enable focused light to be captured along a curved arc or surface, over a number of hours. This aspect of the invention, which will be discussed in greater detail when referring to FIGS. 4A through 4C, results in a need for a concave collector to be provided having a curved concave receiving surface, with this surface positioned in spaced relationship to, and axially aligned with, the focusing element. The possibly most preferred concave collectors will be configured having a surface with a concave curvature that is determined by (or matched to) the focusing element employed. Further, when a plurality of solar energy concave collectors are employed and positioned in one-to-one aligned and spaced relationship to a corresponding plurality of focusing elements--at a distance equal to the focal length--then the solar energy receiving surface of each concave collector enables focused solar energy to be received over a determinable temporal interval.
Accordingly, when considering the dome or spherical shaped solar energy collecting apparatus of the invention, a group of tightly packed and adjacent solar energy collecting structures (e.g., focusing-collecting pairs) will actively enable the collecting of energy over an interval of hours each day, while other groups located upon other portions of the curved surface of the collecting apparatus, will be actively collecting solar energy over another group of hours. As such, a properly curved surface which includes a plurality of closely spaced focusing elements that will be facing the Sun during differing hours of the day, will provide an extended temporal interval during which solar energy may be received and collected.
Yet another aspect of the preferred embodiments of the invention calls for the inclusion of one or more thermal coupling structures. Included thermal coupling structures enable a thermal coupling of each concave collector in order to transfer received and collected solar energy to a heat producing output of the invention. Heat energy delivered to the output of the solar energy collecting apparatus may be employed for at least one of:
a) a storing of the collected solar (heat) energy; and
b) a using of the collected energy as a heat source for powering a variety heat-powered items and mechanisms.
Several preferred thermal coupling structures will be discussed hereinafter. However, the present invention may be employed with many suitable and varied thermal coupling structures, which may be utilized with a variety of energy storage arrangements and or heat powered mechanisms.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings, like elements are assigned like reference numerals. The drawings are not necessarily to scale, with the emphasis instead placed upon the principles and features of the present invention. Additionally, each of the embodiments depicted are but one of a number of possible arrangements utilizing the fundamental components and concepts of the present invention. The drawings are briefly described as follows:
FIGS. 1A and 1B provide illustrations of well known prior art Fresnel lens constructions, which function by taking a point source light source (e.g. an oil lamp or incandescent lamp) and directed light therefrom for forming a parallel beam of much more concentrated light.
FIGS. 2A, 2B, and 2C depict how the curvature of a basic single convex lens (FIG. 2A) can be reduced (FIG. 2B) to discrete lens portions, to yield an equivalent Fresnel lens (FIG. 2C), which clearly has a significantly reduced mass and weight.
FIG. 3A illustrates a traditional light ray diagram for a Fresnel lens showing how the light rays of a point source are redirected in order to produce a powerful and concentrated beam of light.
FIG. 3B illustrates the use of a focusing element of the invention, depicted as a conventional multi-prism Fresnel lens, wherein substantially parallel light rays of incident (incoming) solar light energy are focused at a pre-determined and focal point for providing concentrated and collectable solar energy.
FIGS. 4A, 4B, and 4C depict a representative solar energy collecting structure of the invention, which as shown enables focused solar energy to be efficiently collected over a temporal interval that may be as long as a number of hours, by employing a concave collector having a concave solar energy receiving and or collecting surface.
FIG. 5A is a simplified and somewhat conceptual depiction of a first embodiment of a solar energy collecting structure including a concave collector structure that is thermally coupled to a heat energy conduction mechanism, for coupling the collected heat energy to a selected device, apparatus, or sub-system.
FIG. 5B is a simplified and somewhat conceptual depiction of a second embodiment of a solar energy collecting structure including an alternate concave collector structure wherein an optical material receives and accepts focused solar energy and optically transmits and thermally couples the energy into a heat energy conduction mechanism.
FIG. 6A provides a conceptual and simplified embodiment of a portion of a fixed solar energy collecting apparatus in accordance with the invention that will collect solar energy over a pre-determined and extended temporal interval.
FIG. 6B provides a conceptual and simplified depiction of another embodiment of a portion of a fixed solar energy collecting apparatus, which employs an optical concave collector structure.
FIGS. 7 and 8 provide high level block-type diagrams of several possible embodiments of fixed structure solar energy collecting apparatus of the invention.
FIG. 9 depicts a partial solar energy collecting dome wherein a fixed curved surface includes a plurality of solar energy collecting structures, enabling solar energy to be collected over a larger or expanded temporal interval (e.g., 12 hours) when compared to a single solar energy collecting structure (e.g., a focusing-collecting pair).
FIGS. 10A, and 10B provide detailed examples of several curved outer surfaces formed of a preferably minimal framework of coupled elongated members, establishing a plurality of openings having selected geometric shapes configured for (as illustrated) supporting and fixing a focusing element therein.
FIG. 11 illustrates a more detailed first embodiment of a dome shaped surface including a plurality of focusing elements, with a sub-structure supporting a corresponding plurality of concave collectors.
FIGS. 12 and 13 depict solar energy collecting dome arrangements, which are consistent with the embodiment of FIG. 11, but further adding a vent that may function as an exhaust vent in such embodiments.
FIG. 14 depicts an alternate solar energy collecting dome apparatus wherein a fixed curved outer surface includes a plurality of solar energy focusing elements supported by a support structure, with a plurality of corresponding concave collectors each individually supported by a thermal conduction stem, which both supports the concave collector at the appropriate distance below the corresponding focusing element while also transferring collected solar energy to another structure coupled to a second end of each respective stem (not explicitly shown).
PARTIAL LIST OF REFERENCE NUMERALS
20,20-1, . . . --solar energy collecting apparatus
24--solar energy collecting structure
30a--bulls-eye lens (of 30)
30b--(prism) ring lens (of 30)
40--(solar energy) concave collector
40a--solar energy receiving surface (of 40)
40-1--optical concave collector
40-1a--(optical) solar energy receiving surface
54--heat transfer fluid
60a--elongated member (of 60)
62--solar energy collecting dome
64--curved surface (of 62)
70--heat energy conductor
78--heat accepting (utilizing) portion
80a--top opening (of 80)
102a--reflected and refracted light ray
102b--refracted light ray
104--directed light beam
120--Fresnel lens assembly (prior art)
130--Fresnel lens (prior art)
130a--bulls-eye lens (of 130)
130b--prism ring lens (partial or full)
140a--bulls-eye lens portion (of 140)
140b--prism ring portion (or 140)
142--curved surface (of 140)
200--concentrated solar energy
204--directed incident solar light rays
204a--reflected and refracted solar rays
204b--refracted solar rays
F1,F2,F3--(respective) focusing elements
DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION
It is important to establish the definition of a number of descriptive terms and expressions that will be used throughout this disclosure. The term `temporal interval` will be employed to indicate a period of the daylight hours. For example, a common temporal interval will be approximately in the range of 3 to 6 hours for each focusing-collecting pair. As will be discussed, the actual temporal interval over which useful amounts of solar energy may be focused and collected can vary with the specific structure and configuration of the respective embodiment, as well as items such as the latitude and or the general location of the embodiment, the season of the year, prevailing weather cycles, etc. The terms `significant portion`, `significant area`, and the like, when employed for discussing the area of solar energy focusing surfaces, formed substantially of a plurality of focusing elements, relative to the total area of the curved surface. It may be assumed that a significant area of a curved (outer) surface may certainly be provided by, or associated with, the plurality of focusing elements. For example, typically at least 80 to 90 percent of the total area of a such a curved surface will be associated with the focusing elements (or included clear or possibly tinted optical covers). The terms `curved surface`, `curved outer surface`, and equivalents, may be assumed to indicate that the overall outer surface of the solar energy collecting apparatus is curved, and most preferably configured having a dome or spherical shape. It should be understood that an invention providing a curved surface having the shape of a dome or sphere may certainly include only a portion, section, and or slice, of the dome or sphere.
Continuing, the term `substantially` will be employed as a modifier to indicate either exactly or quite close to the given feature, structure, or characteristic. For example, the phrase `substantially dome shaped` may indicate that the portion of a curved surface of the invention is exactly spherically shaped or close to spherically shaped, with say one dimension (e.g., width) greater than a second dimension (e.g., the depth) by up to ±5 to 10 percent. In like fashion, the terms `substantially orthogonal`, `substantially orthogonally oriented`, etc., can be assumed to mean that the members may be exactly fixed or rigidly coupled to each other at a true 90 degree angle, or alternately somewhat close to 90 degrees. As such, substantially orthogonal members may actually be up to ±5 to 10 degrees or so from a truly orthogonal arrangement, and still be correctly termed substantially orthogonal. Importantly, the terms `coupler`, `coupled to`, `coupling`, etc., are to be understood to mean that two or more described items are either directly connected together, or alternately, connected to each other via one or more additional, possibly implied or inherent structures or components. When considering the thermal coupling structures compatible with the invention, a heat providing output of each concave collector may be provided that is `thermally coupled` to other heat transferring elements, where various thermally conductive components may be needed, such as elongated heat conductive conduits, heat transfer fluid, thermal junction conducting grease or pads, and any required fasteners and or mechanical holding means. Further, these thermal conductive means may not be explicitly illustrated and discussed in any significant detail--as these items are well understood by skilled persons. Other important terms and definitions will be provided, as they are needed, to properly define the present invention and its associated novel characteristics and features. In addition, the terms and expressions employed herein have been selected in an attempt to provide a full and complete description of the invention. These terms may very well have equivalents known to skilled individuals, which may be long established in the art. As such, the terminology employed has been carefully chosen and is intended for illustration and completeness of description, and may very well have equivalents that are known in the art, but not employed here.
Referring now to the drawings, FIGS. 1A and 1B provide depictions of well known prior art Fresnel lens assemblies 120. The specific Fresnel lens assemblies 120 illustrated are typical of complex lens constructions used for many decades in maritime lighthouses. These assemblies actually included a number of Fresnel lenses 130 in each assembly 120. These types of Fresnel lenses functioned by taking a point source light source (e.g. a candle or an oil lamp in the very early years) and directing the light from the light source for forming a powerful, directed, and greatly concentrated beam of light.
One important aspect of each Fresnel lens 130 of the assembly 120, as clearly shown in FIGS. 1A and 1B, calls for each included Fresnel lens to be formed of a number of discrete portions. For example, if one considers the convex lens of FIG. 2A, say having a diameter of 1 meter, the lens will have a very significant weight. However, as discovered by the French scientist Augustin Fresnel, it is actually the curved portions 140a, 140b, . . . , that provide for the focusing and needed light ray re-direction. As such, the hashed area 138 of FIG. 2B, may be omitted and the remaining portions, including 140a, 140b, etc., can be provided as a substantially planar or flattened (Fresnel) lens 130--while still mimicking the function of the original convex 140. That is, by design a Fresnel lens reduces the amount of material required (and associated weight) when compared to a conventional spherical lens by breaking the lens into a set of concentric annular sections known as Fresnel zones. In the early (and largest) variations of these lenses, each of these zones was a different prism. Though a lens might look like a single piece of glass, a closer examination typically reveals that the lens is actually many smaller separate pieces. As technology advanced, it became possible to turn out large and complex Fresnel lenses that were formed essentially of a single monolithic piece of glass, plastic, quartz, etc. It must be noted that a reduced material/weight Fresnel lens is an ideal low cost lens that is usable for focusing light for non-imaging purposes.
As shown in FIG. 3A, a typical Fresnel lens 130 may actually be constructed of a plurality of separate sections, or alternately formed of a single monolithic material and or construction (as depicted in FIGS. 4A through 7). Importantly, a portion of the divergent light rays of FIG. 3A, including light rays 102a, 102b, ect., that are emitted from the light source 100, are re-directed (via reflection and or refraction) to yield a directed light beam 104, which is now concentrated and directed to travel substantially parallel to the focal plane 108. In contrast, and as clearly illustrated in FIG. 3B, this arrangement may be reversed. That is, the use of a focusing element of the invention, preferably in the form of a Fresnel lens 130, enables substantially parallel incoming solar light rays of incident solar energy to be focused to converge at a known and or pre-determined focal length 110--providing notable concentrated solar energy at the focal point. It may be noted that the terms focal length and focal point are often considered equivalents. Importantly, in the case of the present invention, a known fixed focal length of a focusing element (such as Fresnel lens 130) will determine the location to position an associated concave collector that must be positioned in an appropriate spaced relationship to, and with a suitable (in-line) axial alignment with, at least one focusing element.
Turning now to FIGS. 4A, 4B, and 4C, a helpful depiction of how the solar energy collecting structure 24 of the invention, which is somewhat conceptually illustrated, enables focused incident solar energy to be efficiently collected over a temporal interval that may be as long as several hours or more. As shown in FIG. 4A, if a focusing element 30, here depicted as a Fresnel lens, focuses a light source (e.g., the Sun) that is below the normal focal plane 108, then the focused solar energy will be rotated upwardly and will not be focused upon the reference plane 112. Accordingly, a curved and concave receiving surface will be required if solar energy is to be continually focused upon a collecting surface, such as the solar energy receiving surface 40a of a concave collector 40.
As illustrated in FIGS. 4A through 4C, each concave collector 40 may be supported and fixed in spaced relationship to, and axially aligned with, a focusing element 30, at a distance equal to the pre-selected or known focal length of the focusing element 30. The axial alignment is most preferably as depicted, with the focal plane 108 of the focusing element aligned with an orthogonal projection from the bottom of (e.g., deepest point within) the concave receiving surface of the concave collector 40. When axially aligned at a distance equal to the focal length, it is then possible to focus incident solar energy upon the solar energy receiving surface 40a of a concave collector 40 over an entire temporal interval of typically at least 3 to 6 hours. For the example depicted in FIGS. 4A, 4B, and 4C, the temporal interval would be approximately 2 hours, starting at 8 AM (FIG. 4A) and continuing until about 10 AM (FIG. 4C). However, it must be noted that the actual temporal interval can and will vary with many factors. These factors include the type of focusing element employed, the depth/size of the concave receiving surface 40a, the latitude of a location at which the solar energy collecting structure 24 is located, the season of the year, and or other considerations such as man-made and or natural obstacles.
Returning briefly to FIGS. 4A through 4C, it must be understood that the focusing elements 30 depicted as substantially flattened Fresnel lenses may be provided by other possibly more complicated and or 3-dimensional structures. For example, the focusing elements 30 may include a lens element that is much more spherical in shape (not explicitly illustrated). As appreciated by skilled individuals, such non-planar focusing element embodiments would certainly be much heavier and would most likely need to be constructed using advanced light weight materials. In addition, the focusing elements 30 may include structures to control the intensity of the solar energy reaching each concave collector 40. For example, one simple approach may be to employ tinted filters over a plurality of the focusing elements. Alternately, a more complex solution may include a distance controlling mechanism for varying the distance between a focusing lens of the focusing element 30 and the collecting surface 40a of a concave collector 40. That is, if a concave collector begins to reach a maximum desired temperature, the focusing element may be de-focused by adjusting the distance between an included focusing member and the concave collector, as required, to reduce the solar energy being collected. This mechanical arrangement would not, in any way, provide for tracking and following the position of the sun in the sky--which is not required with the present invention.
To better understand the range and variety of the structural embodiments of the concave collectors 40 that may be employed, attention will now be turned to FIGS. 5A through 6B. As illustrated in FIG. 5A, a first basic embodiment of a basic concave collector 40 is depicted in a simplified and high level cross sectional diagram. As shown, this first embodiment is provided as a portion of a solar energy collecting structure 24 including a focusing element 30 and the concave collector 40. The embodiment of the concave collector 40 as depicted has a first portion 42a, which may preferably be provided by a high melting point material such as steel, and a second portion 42b, which is preferably provided by a low melting point material such as copper. The first portion 42a and the second portion 42b may be thermally joined by employing a thermal coupler 48, such as thermal grease or thermal pads. Accordingly, this preferred concave collector 40 may be provided by a steel-over-copper construction.
As shown in FIGS. 5A and 5B, an important feature of the concave collector 40 is the inclusion of the required concave solar energy receiving surface 40a. As discussed when referring to FIGS. 4A through 4C, this concave receiving surface is a necessity so that the concave collector 40 may receive focused solar light energy over an entire temporal interval. Also, the positioning of the concave collector 40 in proper axial alignment, with a proper spacing relationship that is directly related to the fixed focal length of the employed focusing element 30. Specifically, as shown in the figures including FIGS. 5A and 5B, the focal plane 108 of the focusing element 30 may be preferably arranged to be axially aligned (along the focal plane 108) and substantially orthogonal to the deepest portion of the concave receiving surface 40a--and clearly fixed at a distance therefrom that is equivalent to the focal length of the focusing element 30. As discussed hereinabove, this arrangement enables incident solar energy to be focused, received, and or collected for a temporal interval of at least 6 hours or so.
Returning to FIGS. 5A and 5B, one simple approach for transferring heat energy that is collected by a solar energy collecting structure 24 of the invention is depicted. As shown, this exemplary approach involves transferring heat energy from a receiving location proximate to the solar energy receiving surface 40a using fluid conduits 52, and a flow of heat transfer fluid therethrough. As understood by skilled individuals, the inclusion of one or more cooling conduits 52 enables a preferably closed heat transfer system to be employed wherein a volume of a heat transfer fluid 54 is employed for causing a transferring of collected (solar) heat energy away from the concave collector 40. An included thermal coupling structure, such as a fluid based closed system, will enable a thermal coupling to, and transferring of, collected heat energy to a heat input of a heat powered device to be energized (using collected heat). For example, the collected heat energy may be immediately coupled to a turbine, a heat difference fuel cell, a Rankine Cycle engine, a sterling engine, a steam engine, etc.
Alternately the transferred heat energy may be stored for later use. For example, to store collected heat energy at least one of the following may be employed:
a) a high mass insulated storage tank filled with a suitable fluid, may be heated during daylight hours, and used later for heating purposes;
b) a plurality of dense heat retention thermal bricks; or
c) a molten phase change based system.
Returning now to FIG. 5B, a simplified and somewhat conceptual depiction of a second embodiment of a solar energy collecting structure 24-1 includes an alternate optical concave collector 40-1 wherein an optical receiving of the focused solar energy causes an optical transmitting of the solar energy from a solar energy receiving surface 40-1a to a second location for collection. For example, as shown the second location may be a second surface 40-1b of the optical concave collector 40-1, which may include a collection junction for thermally collecting the received solar (light) energy. That is solar light energy is focused upon the solar energy receiving surface 40-1a by a focusing element 30, causing the solar energy to enter an optically transmissive material (glass, sapphire, etc.), causing optical solar energy to be transmitted (or transferred) to a second end 40-1b, where the solar (light) energy is collected and converted into heat energy. It may be noted that the concave collectors 40 and 40-1 may be provided having proportions and scaling that is quite different then the conceptual exemplary representations of FIGS. 5A through 6B.
Turning now to FIG. 6A, a conceptual representation of a first embodiment of a portion of a fixed structure solar energy collecting apparatus 20-1 is depicted. This simple embodiment employs a support structure 60, along with elongated members 60a, for forming a plurality of openings into which focusing elements 30 are supported and fixed. As shown, the focusing elements 30, along with corresponding concave collectors 40, provide three focusing-collecting pairs, which are angled in 45 degree steps from one to the next. That is, there is a 45 degree rotation from focusing element F1 to focusing element F2, and another 45 degree rotation from focusing element F2 to focusing element F3 This arrangement will enable solar energy to be received and collected over an extended temporal interval, say in the range of 6 to 8 hours.
The embodiment of the solar energy collecting apparatus 20-1 of FIG. 6A depicts an arrangement wherein concave collectors 40 are formed (having a spherical curvature) within a structure that may be termed a heat energy conductor 70, which may be considered to include a thermal coupling structure for aiding in transferring and delivering collected solar heat energy. As shown, the heat energy conductor 70 depicted in FIG. 6A includes a first steel (layer) portion 70a, into which the concave collectors 40 and a solar energy receiving surfaces 40a thereof are formed. As such, the steel portion 70a is provided by what may be termed a `high melting point material` (HMPM), while a copper portion 70b is provided as a `low melting point material` (LMPM). It may also be helpful to provide concave surface 40a as a black colored surface. This structure enables the solar energy focused by the focusing elements 30 to be received and collected, which may involve handling localized temperatures (at the focal point) in the range of substantially 100 degrees to 1600 degrees centigrade, or so.
Returning to FIG. 6A, a concise description of the operation of the solar energy collecting apparatus 20-1 will be provided. The same basic principles of operation will also be consistent with the operation of the embodiments of FIGS. 6B through 14. For the depiction of FIG. 6A it may be noted that North is up, East is to the right, etc. Accordingly, early in the day, the Sun will rise in the East (on the right side of FIG. 6A), and move in a counter clockwise (CCW) direction. Initially, as at 6 AM, the first focusing-collecting pair including focusing element F1 and the axially aligned and spaced concave collector 40, will be actively focusing, receiving, and collecting solar energy. In addition, a second focusing-collecting pair (with F2) will also be focusing, receiving, and collecting solar energy. However, at 6 AM in the morning the third focusing-collecting pair (with F3) is not actively receiving solar energy. As the day progresses, the Sun will rise. At 9 AM all three focusing-collecting pairs depicted in FIG. 6A will be actively focusing, receiving, and collecting solar energy.
An alternate manner in which to analyze the solar energy collecting capabilities of the embodiment of FIGS. 6A and 6B, and equivalent arrangements that employ a plurality of focusing-collecting pairs, is to consider the temporal intervals over which each focusing-collecting pair will be actively collecting solar energy. When considering the F1 focusing-collecting pair, as depicted, solar energy would be actively collected during an interval starting from approximately sunrise and continue until about 9 AM--at which point the angle of the Sun will soon no longer permit the focusing element F1 to focus solar energy upon the concave receiving surface 40a of concave collector 40. For the F2 focusing-collecting pair, an active interval (as depicted) would be from about 6 AM until about Noon. And for the F3 focusing-collecting pair the active temporal interval would be from about 9 AM until about 3 PM.
As a skilled individual would appreciate, the more focusing-collecting pairs that are included, especially when preferably tightly spaced so as to substantially form a (convex) curved spherical surface, the more solar energy the apparatus of the invention can collect per unit time. A further discussion of this practical implementation aspect of the present invention will be provided when discussing FIGS. 9, 10A, and 10B.
Turning now to FIG. 6B, another embodiment of a solar energy collecting apparatus 20-2 provides the same arrangement of support structure 60/60a and spaced focusing elements 30 as was found in the embodiment of FIG. 6A. However, in FIG. 6B a modified heat energy conductor 70-1 now employs a optical concave collector 40-1 which is arranged with a transparent concave surface 40-1a for receiving solar energy focused upon the surface 40-1a. The received solar (light) energy will be optically received causing an optical transmitting of the received solar energy to a second end 40-1b of the concave collector 40-1. As depicted, at the second end 40-1b the solar (light) energy may be converted to heat energy effecting a heating of portion 70a, which may best be provided as a high melting point material (HMPM) for aiding in collecting and transferring the heat energy for storage and or immediate use. It may be noted that the body of the optical concave collector 40-1 may be constructed using any suitable optical transmission material including at least one of sapphire, quartz, ruby, high temperature glass, etc. Importantly, the actual material employed for an optical concave collector 40-1 may actually depend on the respective embodiment in which the concave collector 40-1 is employed and factors such as the latitude of the installation, the rate at which solar (heat) energy is transferred and or utilized, the size and quality of the focusing elements employed, etc.
Turning now to FIGS. 7 and 8, two high level block-type diagrams of several other embodiments of fixed structure solar energy collecting apparatus of the invention will be discussed. As can be seen in FIG. 7, a plurality of tightly packed/spaced focusing-collecting pairs are provided. Each focusing-collecting pair includes a focusing element 30 which is axially aligned and supported/fixed in spaced relationship to a concave collector 40. As discussed when referring to FIG. 6A, the concave collectors 40 may be formed (e.g., cast) within a high melting point material (HMPM), which may be realized as a first steel portion 70a. The steel portion 70a is again a first HMPM layer that covers a second LMPM layer, depicted as a copper portion 70b. A thermal coupling 72 may be provided between the steel portion 70a and the copper portion 70b, as required.
Importantly, as indicated in FIG. 7, the simplified focusing-collecting pairs, with a focusing element 30 axially aligned and paired with a concave collector 40, may be considered a `heat collection` front end. As further illustrated, the heat collection front end may be coupled to additional heat transporting layers, such as the first (HTMP) steel portion 70a and or the second (LTMP) copper portion 70b, which may be considered at least a portion of a `heat delivery` portion. As shown, a suitable thermal coupling arrangement, including thermal coupling 72 and heat energy conductor 70, may be employed for coupling and delivering the collected solar energy to a heat accepting portion 78. For example, if the collected solar energy is to be stored, the collected solar energy may be employed to increase the temperature of a heat storage mass, such as provided by a mass of high density thermal bricks. Alternately, the collected heat may be, at least in part, used immediately to power a heat-to-torque converting mechanism, such as a sterling engine.
Referring now to FIG. 8, a high level block diagram representation of a possibly most generalized solar energy collecting apparatus 20 includes a plurality of focusing-collecting pairs, with each including a focusing element 30, a concave collector 40, along with the required support structure 60. The functions of the focusing element 30 and concave collector 40 are as discussed hereinabove. The support structure 60 may be employed for multiple purposes, including a supporting of the focusing elements within voids or openings of the support structure, while also possibly supporting each of the concave collectors--possibly with separate or discrete supporting structure portions.
It should be understood that the embodiment of FIG. 8 may provide for the focusing-collecting pairs to be tightly packed, with juxtaposed (adjacent) focusing-collecting pairs oriented slightly off axis (say by 2 to 5 degrees) with other proximate focusing-collecting pairs. A depiction of one preferred embodiment of a solar energy collecting apparatus having a plurality of tightly packed focusing-collecting pairs, which is consistent with the high level representations of FIGS. 7 and 8, is provided in FIG. 9. As clearly shown in FIG. 9, an outer or exterior planar surface of the focusing elements 30 provides a substantial portion of a curved (outer) surface 64 of a solar energy collecting dome 62. The dome 62 is shown installed upon a roof 90 of a building 86, wherein the building may further include other items, which are not explicitly illustrated, such as energy transfer, energy storage, and or energy conversion means. It may be noted that the openings of FIGS. 9, 10A, and 10B, may actually be spaced somewhat further apart, possibly with a heavier framework structure and thicker elongated members. The actual spacing of one focusing element from another, along the curved surface 64 may best be determined by the underlying structure and spacing of the plurality of concave collectors 40, and the associated concave collector and thermal coupling structures employed therewith.
Returning briefly to FIG. 8, the solar energy collecting apparatus 20 may include a solar energy heat collection function or portion, as well as a heat energy transfer function or portion. In practice, such means will certainly be required, and have been depicted in FIG. 8 as the heat energy conductor 70 and the heat accepting portion 78. Contemplated `heat accepting portions` will enable collected heat energy that is received from a heat energy conductor 70 via a thermal coupling 72 to be stored (for later use when needed) and or employed as a heat input source (for immediate use) to a variety of devices and systems that immediately use the available heat energy.
When considering the most efficient and practical embodiments of the present invention, a variety of preferred curved surfaces 64, as depicted in FIGS. 9 through 14 will now be discussed. When considering such embodiments of the solar energy collecting apparatus 20, an included support structure 60 may include a plurality of coupled elongated members 60a, and or other pre-formed components (not illustrated) for forming a plurality of closely or tightly packed and non-overlapping voids or openings 66. As depicted in FIG. 9, each of the openings 66 may be substantially filled by a focusing element 30. For the depictions of FIGS. 10A and 10B, the focusing elements 30 are provided as Fresnel lenses, which are substantially planar and form at least 80 to 90 percent of an exterior surface of the curved surface 64. As discussed hereinabove, alternate lens structures of the focusing elements may be more ball or sphere-like in shape (not shown), causing the curved (outer) surface of the apparatus to have a much less flattened appearance.
Turning again to FIGS. 10A and 10B, it should be noted that the openings 66 may be provided having any useful and efficient shape. For example, as shown the openings 66 of FIG. 10A are hexagonal in shape, while the openings 66 of FIG. 10B are substantially quadrilateral in shape. However, other shapes may be employed when forming the openings, including one or more of triangular, octagonal, honey-comb shaped, circular, etc.
Similarly, when considering preferred outer or overall exterior shapes employable with the embodiments of the solar energy collecting apparatus 20 of the invention, generally spherical, ball, dome, or other curved shapes and the associated curved outer surfaces, may be most preferred. These and other possible shapes are specifically employed to place and orient a plurality of proximate, preferably tightly packed focusing-collecting pairs to be able to actively receive and collect solar energy during most of the hours of a typical sunny day. However for one or more reasons, a full sphere or dome may not be needed, required, or practical. As such, other curved shapes such as a partial dome, a partial hemispherical shape, or a section/slice of a sphere or hemisphere may be most preferable. In addition, although preferred smooth curved surfaces are depicted in the figures, other less smooth surfaces possibly having discontinuities and other protruding structures are certainly contemplated.
Turning now to FIG. 11, a portion of a dome shaped solar energy collecting apparatus 20-4 is shown with an inner possibly dome shaped heat energy conductor 70. As shown, a (solar) heat energy conductor 70 may be formed with a plurality of concave collectors 40 formed within the conductor 70. It may be noted that as depicted, a first support structure 60 including a plurality of elongated members 60a may be employed for supporting and fixing the focusing elements for forming the curved surface 64 of the solar energy collecting apparatus. In addition, a very different and inner second support structure may be employed in the form of the heat energy conductor 70 for supporting inner concave collectors 40 in aligned and spaced relationship to the focusing elements 30 of the outer curved surface 64.
A number of possible additions and or alterations to the basic solar energy collecting apparatus 20-4 of the invention is certainly contemplated. For example, as shown in FIGS. 12 and 13, the basic dome or sphere shaped curved surface of a solar energy collecting apparatus 20-5 may be modified to include an air exhaust vent 80 providing an opening 80a to an interior within the curved surface 64. The vent 80, and opening 80a may be employed for a number of uses ranging from passive cooling to solar-to-wind powered generation mechanisms.
As shown in FIG. 14, yet another possibly embodiment of a solar energy collecting apparatus 20-6 includes an alternate internal structure for supporting and thermally coupling to the concave collectors 40. As shown, each concave collector 40 may be supported by at least one stem 44. Each stem 44 must be strong enough to support the weight of a concave collector 40, as well as provide an efficient thermal coupling of the concave collector 40 to an included heat energy conductor, or an equivalent structure, for enabling the received and collected solar energy to be output as a heat source. Accordingly, the stems 42 may be provided having complex internal structures for enabling collected heat energy to be readily delivered for storage or energizing an included heat powered mechanism.
While there have been described herein a plurality of the currently preferred embodiments of the means and methods of the present invention, those skilled in the art will recognize that other and further modifications may be made without departing from the invention. For example, other support structures may be employed for supporting the focusing element and or concave collectors of the invention. As such, the foregoing descriptions of the specific embodiments of the present invention have been provided for the purposes of illustration, description, and enablement. They are not intended to be exhaustive or to limit the invention to the specific forms disclosed and or illustrated. Obviously numerous modifications and alterations are possible in light of the above teachings, and it is fully intended to claim all modifications and variations that fall within the scope of the appended claims provided hereinafter.