WO2021119795A1

WO2021119795A1 - Solar energy collector

Info

Publication number: WO2021119795A1
Application number: PCT/CA2019/051849
Authority: WO
Inventors: Robert De Chazal
Original assignee: Sundraco Power Inc
Current assignee: Sundraco Power Inc
Priority date: 2019-12-18
Filing date: 2019-12-18
Publication date: 2021-06-24
Anticipated expiration: 2022-06-18

Abstract

A solar energy collection system has a radiation concentrator in the form of a horizontally elongate parabolic reflector having a focus line; a heat exchanger comprising a target conduit which lies along or adjacent to the focus line of the parabolic reflector and carries a thermal fluid; and a subsystem configured to move the thermal fluid through the heat exchanger.

Description

SOLAR ENERGY COLLECTOR

Field of the Invention

[0001] The present invention relates generally to systems and methods for collecting heat energy from solar radiation, and delivering it for use in electrical power generation, industrial systems, and/or space heating.

Background

[0002] There is a need in the art for efficient collectors of useable energy from the concentration of solar radiation.

Summary

[0003] In one aspect, the invention may comprise a solar energy collection system comprising: a) a radiation concentrator comprising a horizontally elongate parabolic reflector having a focus line; b) a heat exchanger comprising a target conduit which lies along or adjacent to the focus line of the parabolic reflector and carries a thermal fluid; and c) a subsystem configured to move the thermal fluid through the heat exchanger.

[0004] In some embodiments, the parabolic reflector has a shape consisting of one segment of a parabola taken from one side of the parabolic plane of symmetry.

[0005] In some embodiments, the radiation concentrator may comprise a plurality of optical panel arrays, arranged in a horizontal row. Each optical panel array may comprise a plurality of optical panels, arranged in a vertical row, wherein each optical panel has a curved reflective surface. The radiation concentrator may comprise an optical panel array cluster comprising a plurality of optical panel arrays, mounted on a framework of support beams, such as parabolic I-beams, and a support truss.

[0006] In some embodiments, the radiation concentrator is mounted on a substructure, configured to be rotatable about a horizontal axis substantially coincident with the focus line. The substructure may comprise a base, a pivot arm which pivots about the horizontal axis, and an elbow pivot for pivotably mounting the optical panel array cluster to the pivot arm, by means of an extension arm depending from the cluster. The optical panel array cluster may be rotated by movement of the pivot arm and/or the elbow pivot.

[0007] In some embodiments, the system may comprise opposing optical panel arrays, on opposing sides of the target conduit.

[0008] In some embodiments, the target conduit may comprise an inner exchanger conduit and an annular gap conduit, wherein the gap conduit defines a longitudinal gap which receives solar energy from the radiation concentrator, and the exchanger conduit comprises a hot pipe, a portion of which is exposed to the gap, and a cold sleeve partially surrounding the hot pipe. Optionally, the hot pipe and cold sleeve are separated by an insulating space.

[0009] The gap may be sealed with a gap insert, comprising spaced apart ambient air tubes and a transparent window allowing passage of solar energy through the gap insert. The gap insert window may comprise a lens for modulating the shape of solar energy passing through the gap insert. [0010] In some embodiments, the ambient air tubes may define a plurality of perforations for directing forced outside air into the gap conduit. Preferably, each ambient air tube defines two rows of perforations, which direct air at an oblique angle into the gap conduit.

[0011] In some embodiments, the hot pipe comprises inner guides for causing non-linear or turbulent flow of the thermal fluid within the hot pipe, which is preferably helical flow.

[0012] In some embodiments, the portion of the hot pipe exposed to the gap comprises a heat transfer strip, which is preferably formed from an efficient heat conductor and/or heat absorber, and preferably has an outer surface which is crenulated.

[0013] In some embodiments, the system further comprises a control system operatively connected to means to rotate the radiation concentrator and/or means to move thermal fluid through the target conduit, the system configured to:

(a) rotate the radiation concentrator in accordance with the measured or predicted elevation of the sun above the horizon;

(b) rotate the target conduit along its longitudinal axis;

(c) control the flow rate of thermal fluid through the target conduit; and/or

(d) control the recycle rate of thermal fluid within the target conduit.

Brief Description of the Drawings

[0014] 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 of the present invention. Additionally, each of the embodiments depicted is but one of a number of possible arrangements utilizing the fundamental concepts of the present invention. [0015] Figure 1 is a schematic depiction of the solar troughs of one embodiment.

[0016] Figure 2 is a perspective view of one embodiment of a concentrated solar power trough segment.

[0017] Figure 3 is a perspective view of a back of an optical panel array cluster (OP AC). [0018] Figure 4 is a perspective view of a optical panel array (OP A). [0019] Figure 5 is a schematic representation of the parabolic geometry of one embodiment.

[0020] Figure 6 is a perspective view of an OP AC aimed at focal line on a target conduit. [0021] Figure 7 is a perspective view of a folded OP AC.

[0022] Figure 8 is a schematic representation of a double-sided deployment, with two OPACs arrayed with a single target conduit. [0023] Figure 9 is a perspective view of a parabolic I-beam (cap removed) and an optical panel.

[0024] Figure 10 shows an optical panel linking device, with an inset showing a detailed view.

[0025] Figure 11 is perspective cross-sectional view of a target conduit and its support and control structure. Figure 11a shows a detail of a gap insert in cross section. Figure 1 lb shows the cross-sectional view of the hot pipe with the central screw.

[0026] Figure 12 shows a partial cutaway and exploded view of a target conduit, showing a gap insert, with an insert showing a detailed view. [0027] Figure 13 is a perspective view showing seasonal positions of an OP A, rotated about an axis coincident with the target conduit.

[0028] Figure 14 shows a cutaway view of a target conduit, showing a riffle wing and fins.

[0029] Figure 15 shows a schematic representation of fluid flow in a target conduit, with an inset showing a detail of a recycler.

[0030] Figure 16 shows a cross-sectional view and a perspective view of the target conduit turnaround of one embodiment.

Description of Embodiments of the Invention

[0031] As used herein, the terms “vertical” and “horizontal” are used to describe the relative positioning, orientation or direction of certain elements, based on a substantially horizontal array, where the parabolic focal line is substantially horizontal. The present invention is not restricted to any one orientation, however, so these terms are not intended to be absolute limitations.

[0032] In some embodiments, the invention may comprise one or more of the following features of the elements of the device.

Concentrator

[0033] The radiation concentrator comprises coordinated arrays of light-reflective surfaces, called optical panel arrays (“OP As”) (202), configured in an optical panel array cluster (“OP AC”) (200), which is an assembly of OPAs in a shallow trough having a curved cross- section, as shown in Figures 4 and 5. Each OPA comprises a plurality of optical panels (“OPs”)

(201). In one embodiment, each OP is a plank-like, long and narrow rectangular prism, the front side of which is made highly reflective while the back and side surfaces are preferably covered with a protective coating. The prism may be composed at least in part of a light-weight, rigid material. The OPs (201) are vertically stacked, with their long dimension horizontal as shown in Figure 2 and 4, to form an OPA (202), such that each OPA forms a single reflective surface. Each OPA is substantially parabolic in cross-section, which focusses light on a substantially horizontal line (’’focal line”) (203), as shown in Figure 5, located along or very near a target conduit (“TC”) (300) and parallel with it, as shown in Figure 6.

[0034] Each OP (201) has a reflective surface, such as is shown in Figures 2 and 4, which is itself a shallow curve in cross-section unique to the OP’s position within the OPA (202), ensuring that the OPA as a unit behaves, aside from contact lines between the OPs, as if it were a single, smooth, parabolic reflective surface. The overall reflective surface of the OPA (202) is shaped as a segment of one side of a parabola, which segment is called the “defining parabola” (204), as shown in Figure 4. Figure 5 illustrates how one so-called side of a parabola is separated from the other by the plane of symmetry of the parabola to which direct solar insolation must be confined for an effective focus to be maintained on the focal line (203). [0035] In one embodiment, the OP As are positioned and aligned along an east-west direction, with OP As facing toward the solar noonday sun whether in the northern or southern hemisphere. Accordingly, the long axis of the TC (300) is parallel and orientated along the east-west line. The focal line (203) of the OP As’ parabola situated on or proximal to the TC on a surface which faces the OP As, as is shown in Figure 5.

[0036] In preferred embodiments, the OP As (202) are mounted on a substructure so as to be rotatable about a horizontal axis which is coincident with that of the TC. Any such rotation may result in the focal line of the OP A not moving, or tracing a small arc about the TC. Accordingly, the OP As may be rotated to track the sun’s changes in its elevation above the horizon throughout the day and seasons. Preferably, the focal line and the TC of an OPA are situated at such a distance from the OPA so as to have the sun shadow of the TC never interfere with the operation of the OPA.

[0037] In one example, as shown in Figures 2, 3 and 7, an OP AC (200) comprises three OP As. In some embodiments, the OP AC comprises a structural framework of light-weight, support beams, which are curved to match the parabolic shape of the OP As. Each beam is preferably an I-beam, referred to herein as parabolic I-beams (“PIBs”) (205) and end PIBs (206), which along with trusses and cables collectively form the structural framework into which OP As are placed. The PIBs act as vertical cross-ribs of the horizontal trough, and which support and control the position of the OP As.

[0038] PIBs (205) are fixed by a horizontal supporting structure, such as shown in Figure 3, which may comprise a light-weight, support truss (208) which is positioned to support each PIB (205, 206). The truss (208) also serves as attachment points for stabilizing, anchor cables (209) connected to the PIBs, which are preferably adjustable.

[0039] OPACs are bracketed at either end by end PIBs (206), which in some embodiments, project below the constituent OP As as PIB extensions (207). An OP AC is supported by support and control structures (“SACS”) (400), as shown in Figure 2, which are suitably anchored to the ground. Thus, OPACs may be firmly attached to one another to form single, continuous parabolic troughs, such as in Figure 1. [0040] Each OP AC may be pivoted about a substantially horizontal axis centred on elbow pivots (403), as illustrated in Figure 2, at least to maintain the sun on the plane of symmetry of the defining parabola throughout collection of radiation by changing the angle of the OP AC. Each such elbow pivot is located on or proximal to the defining parabola (204), or the extension of the same, in such a position below the OP AC so as to avoid shadows of the target conduit, for example, from falling on any OPs during solar energy collection.

[0041] Each OP AC (200) may also be rotated about a substantially horizontal axis, substantially coincident with the axis of target conduit (300), at locations called “shoulder pivots” as shown in Figure 2, which rotation also varies the tilt of the OP AC (200).

[0042] As a result, the combination of the two possible axes of rotation allows the trough to be precisely positioned so as to focus radiation onto, or proximal to, the TC (300), on the intended focal line (203), regardless of the elevation of the sun at any given moment.

[0043] In preferred embodiments, light-weight beams called pivot arms connect the elbow pivots (403) and shoulder pivots (404) as may be seen in Figure 2. The shoulder pivots are attached to Support Posts (402) by conventional mechanisms located on the posts.

[0044] In preferred embodiments, the weight of the OP AC (200) is counter-balanced by a Counterweight (406) on the pivot arm’s extension, as shown in Figures 2 and 7.

[0045] In preferred embodiments, OPACs (200) are rotated about the shoulder pivots (404) and about the elbow pivots (403) sequentially or simultaneously. As shown in Figure 2, the pivoting mechanism for the elbow pivot comprises an elbow pivot cable (407) which extends to and attaches to the top of an end PIB (206), wraps around the TC (300), and attaches to a lower end of a PIB extension (207), the movement of which cable may be controlled by a small motor and winch (408) anchored near on or near the shoulder pivot (404). In another embodiment, not illustrated, a horizontal rod may run the length of the trough through each of its constituent elbow pivots, and be controlled by a pivoting mechanism at one or both ends of the trough. As described below, the pivoting motors or winches may be controlled by a central control system. [0046] Locking mechanisms, not illustrated, will prevent rotation about either or both the shoulder and elbow pivots. If both pivots are locked, the OPACs will be held in position. [0047] The OPACs (200) may be be rotated to track the elevation of the sun throughout the day, either by sensing the sun's position or by predicting the sun's movement given the geolocation of the installation. When necessary the OPACs may be rotated forward slightly about the pivots to shelter their optical surfaces from precipitation, and may also be rotated into a storage or sheltered position with the OP AC facing downward in a near horizontal position, seen in Figure 7. This may be the default non-collection position and may be required in the event of severe winds and weather, when maintenance including the replacement of OPs is required, and in the event of the removal all OPs in emergencies. When in the near-horizontal position, the OPACs come to rest against stops, which, with locks, restrain the OPACs’ movement. When in the near horizontal position, the OPACs may be heated by heat moving through the XC for the purpose of snow and/or ice removal.

[0048] In low latitude locations where at noon the sun is nearly directly overhead in a zenith position, a dual deployment of sets of OPACs (200) may be useful. As shown in Figure 8, two OPACs wings may rotate in unison around the TC. In such cases, the troughs may be orientated with their longitudinal axes running north-south, in contrast to the east-west orientation of OPACs which may be preferred at sites close to and higher than north or south earth latitudes of approximately 40°.

[0049] As may be seen in Figure 9, in one embodiment, the ends of each optical panel (201) are shaped and set in caps called end caps (220) which protect the OP from contact abrasion, which end caps are preferably fashioned from a metal. The end caps have attached to them a guidance mechanism which, in concert with their adjacent PIB (205), allows for thermal expansion while also maintaining the OP (201) in proper optical alignment. In some embodiments, the guidance mechanism comprises an elongated leaf spring (221), as shown in Figure 9, placed between the end cap and its adjacent PIB, which leaf spring is set into a shallow defining parabola groove (222) precisely machined along the length and into the side of the adjacent PIB.

[0050] The leaf spring (221) may also be tensioned to allow for easy installation and replacement of OPs (201) within any OPA (202), which is accomplished in this preferred embodiment by sliding the OP along its defining parabola grooves (222), as illustrated in Figure 9.

[0051] PIBs (205 & 206) may be unitary or, preferably, may be assembled from components. As shown in Figure 9, in one embodiment, each PIB is composed of symmetrical halves, being mirror images of each other down a vertical axis. Each side of each half PIB bears the defining parabola groove (222) while its opposite side is machined flat. The halves may be bolted together, with bolt holes precisely placed so as to ensure the alignment of their defining parabolas when mirror halves are joined, thereby allowing the construction of OPACs and entire troughs. [0052] As shown in Figure 10, in some embodiments, a small linking device (223) connects adjacent OPs (201), which linking device allows for vertical thermal expansion of the attached panels while maintaining a constant link between adjacent panels. The linking device may be a clip of appropriate shape and material which links and bridges the gap between adjacent panel end caps. Alternatively, the function of linking may be accomplished by complementary (dovetailed) profiles built into the ends of the adjacent OPs (not illustrated).

Target Conduit

[0053] In its simplest implementation, the target conduit may simply be a linear pipe, where cold fluid enters at one end, is heated as it passes through the target conduit, and exits the other end. However, in preferred embodiments, the target conduit comprises concentric fluid flows, with a cold side and hot side. In any event, the target conduit is configured to receive solar energy along the focal line of the OP AC, thereby heating a thermal fluid which flows in the target conduit.

[0054] As shown in Figure 11, the target conduit (300) may comprise two concentrically arranged conduits: an outer shell conduit, referred to as a gap conduit (“GC”), (310), and an inner conduit referred to as an exchanger conduit (“XC”) (330). An insulating layer (315) preferably surrounds the target conduit (300), except for a gap portion, as described below. [0055] In a preferred embodiment, as shown in Figures 2, the GC (310) is supported by yokes (411) at the top of each support post (402), and is fixed to the OPACs (200) by mechanisms comprising shoulder pivots, pivot arms (405), and elbow pivot cables (407). Roller bearings (410) support the GC and allow its rotation about its central axis. [0056] In one embodiment, the XC (330) is fixed at either end of the trough, while its GC (310) and its affixed OP AC (200) rotate about the XC (330). In an alternative embodiment (not illustrated), the XC may be fixed to the GC, requiring the entire TC (300) and OP AC to rotate in unison. The latter configuration would require special accommodations to be made at the junction of the TC with whatever outlet flues are required to deliver the heated thermal fluid for its intended purpose.

[0057] In a preferred embodiment, as shown in Figure 11, the GC is formed by, in part, a gap conduit wall tube (311) which is broken by a longitudinal gap which runs substantially the length of the conduit, located close to the focus line of the OPACs (200). The gap is sealed by a transparent gap insert (320) which allows the entry of focused radiation into the interior of the GC. This radiation may enter directly and unimpeded, or the gap insert (320) may include a lens (312) shaped to direct the energy beam to the XC at a desired width.

[0058] As shown in Figure 11, the XC (330) comprises an inner central hot pipe (331), and outer cold sleeve (332), which are separated by an optional insulating vacuum sleeve (333), which insulates the hot pipe from direct heat loss to the cold sleeve. The cold sleeve (332) may be divided into separate compartments. Heat transfer fins may be provided to facilitate heat transfer into the cold sleeve (332).

[0059] The cold sleeve and hot pipe together form a sealed thermal fluid circuit and are connected to one another within the parabolic trough at the far end of the trough where the thermal fluid, having travelled though the cold sleeve, is turned smoothly by a Turnaround into the hot pipe leading back to the origin, as illustrated in the schematic Figure 15. [0060] Between the GC and the XC, an air space is maintained as an ambient air sleeve (313). Because the cold sleeve does not extend entirely circumferentially around the hot pipe, a portion of the hot pipe is exposed to an enlarged entry chamber (312). Thus, the entry chamber allows the direct exposure of a segment of the wall of the hot pipe, the heat transfer strip (“HTS)”, to focused radiation entering the TC.

[0061] A gap insert (320), shown in Figures 11 and 12, comprises upper and lower spaced apart ambient air tubes (“AAT”) (321), a lens cradle (324), and a plurality of lenses (326). The AATs are affixed to either side of the lens cradle, and are sealingly seated into the gap in the Gap Conduit Wall (311) by way of the AAT Flanges (323). The lens cradle ribs (325) bridge the gap between the AATs to provide strength to the GC, while providing seating for the Lenses. Lens Bevels (327) in the ends of the Lenses are preferably reflective so as to allow as little loss of incoming concentrated insolation as possible, while also allowing room for the lens cradle ribs. [0062] The AATs (321) are open at one end and receive forced ambient air by a fan (not shown). As shown in Figure 11, the AATs (321) distribute ambient air along the length of the TC (300), and to release it into the entry chamber (312) through a plurality of AAT perforations (322). In one preferred embodiment, each AAT comprises two lines of perforations (322), one line sending a fine stream of ambient air out towards its adjacent AAT, and one away, as shown in Figure 11.

[0063] The air flow through the AAT helps cool the gap insert (320), which is exposed to very high temperatures within the entry chamber, and directs heated air into the entry chamber toward the ambient air sleeve (313), where it serves to transfer otherwise wasted heat to the cold sleeve. Perforations (314) in the GC Wall (311) allow release of air from the ambient air sleeve to the surroundings.

[0064] As shown in Figures 11, 12, 13, and 14, the wall of the hot pipe (331) exposed to the entry chamber (312) comprises at least one heat transfer strip (334), which strip runs the length of the hot pipe aligned with the gap in the gap conduit outer wall. As the GC (310) and connected OPACs (200) rotate with the yearly changes in the elevation of the sun, as shown in Figure 13, a narrow band of focused radiation will migrate across the HTS, depending both on the time of day and the time of year. The HTS may be formed of a material which is an efficient heat conductor, such as any appropriate metal. The HTS is preferably painted or colored in a black colour, to enhance heat absorption.

[0065] In preferred embodiments, the outer surface of the HTS (334) is crenulated for greater surface exposure, as shown in Figure 11, and the inner surface of the HTS comprises small extrusions or fins, called riffles (343), which expand the heat transfer surface area, and cause turbulence, eddies, and small vortices in the thermal fluid moving across them, which turbulence enhances heat transfer to the thermal fluid.

[0066] The hot pipe (331) may include internal guides to the flow of thermal fluid within the hot pipe. In a preferred embodiment, as shown in Figure 11, the guide is in the shape of a screw, the Central Screw (340), which forces the thermal fluid into a helical, or cyclonic, path, causing it to sweep obliquely across the inner surface of the HTS (334), as illustrated in Figure 14. In a preferred embodiment, the central screws are anchored near the top of each support post (402), and extend into the XC toward the next support post. [0067] In some embodiments, as shown in Figure 14, as the thermal fluid follows its helical path, riffle wings (341) force it toward the HTS (334). Turbulence caused by riffles (343) on both the riffle wing and the HTS will increase the transfer of heat to the thermal fluid. Riffle wing fins (342), illustrated in Figure 14, transfer heat radiated by the HTS (334) to the passing thermal fluid.

[0068] Thermal fluid circulates from end-to-end in the trough in the cold sleeve (332), as shown schematically in Figure 15. Although Figure 15 shows the cold sleeve and hot pipe as being a U-shaped conduit, they are concentrically disposed in preferred embodiments, as shown in Figure 11. As used herein, "concentric" means that one flow path is disposed within another flow-path. The conduits need not share geometric centers, but may be offset.

[0069] At the far end from the entry to the cold sleeve, the thermal fluid enters a turnaround (334) where the fluid is redirected into the hot pipe for its return trip through the TC, as shown in Figure 16.

[0070] In a preferred embodiment, as shown in the schematic Figure 15, a recycler (350) shunts some of the heated thermal fluid from the hot pipe (331) back into the cold sleeve to permit the thermal fluid to achieve an appropriate operating temperature. In the recycler (350), an adjustable valve or nozzle (352) permits some heated thermal fluid to exit the device while redirecting some fluid to the cold sleeve by way of a shunt (353) and a Venturi tube (355). The nozzle (352) may be adjusted such that all or substantially all of the heated fluid exits the device, in situations where at least a portion of the thermal fluid reaches a desired temperature with a single pass through the XC. The nozzle may be controlled by a control system to provide a suitable or desired level of recycling of heated fluid. Suitably located temperature sensors will provide temperature data to guide the control system.

[0071] The heated thermal fluid from the hot pipe may then be transported to its end use which may be as heat itself, or the conversion of its heat to mechanical or electrical energy by way of a heat engine.

[0072] The thermal fluid may be any suitable liquid or gas, but is preferably a gas such as nitrogen or air, or, with an appropriately modified TC, a liquid such as a thermal oil. A relatively inert gas such as nitrogen may be preferred. If a liquid is used, and the system reaches a temperature above the liquid boiling point, then suitable pressure controls will be required. [0073] All materials used in the system will be suitable for its intended purpose, which is well within the skill of one skilled in the art. Materials with suitable temperature-refractory properties must be chosen for components which may reach very high temperatures, particularly components in the target conduit, which may receive focused solar radiation. Control System

[0074] A control system may be operatively connected to different sensors and actuators to configure any adjustable aspect of the system, for purposes of efficiency and/or safety. For example, actuators may operate pivoting of the pivot arm (405) and the elbow pivot (403), in accordance with the measured or predicted elevation of the sun above the horizon, in order to position the focus line of the OP AC by rotating the OP AC. As well, the GC may be rotated along its central axis to suitably position the gap to receive the reflected solar energy. As well, the flow of thermal fluid through the XC may be controlled in response to the amount of solar energy available. If cloudy conditions, or early or late day conditions reduce the amount of solar energy available, the flow rate of thermal energy may be reduced and/or thermal fluid recycling increased, to achieve a desired thermal fluid temperature. Or in mid-day, cloudless conditions, the flow rate may be increased and/or thermal fluid recycling decreased or eliminated, to maximize heat production.

[0075] The control system is preferably a conventional computing device having a processor, memory and implementing computer algorithms configured to implement the control steps described herein. The control system may be completely or partially automated.

Definitions and Interpretation

[0076] The description of the present invention has been presented for purposes of illustration and description, but it is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. Embodiments were chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.

[0077] The corresponding structures, materials, acts, and equivalents of all means or steps plus function elements in the claims appended to this specification are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. [0078] References in the specification to "one embodiment", "an embodiment", etc., indicate that the embodiment described may include a particular aspect, feature, structure, or characteristic, but not every embodiment necessarily includes that aspect, feature, structure, or characteristic. Moreover, such phrases may, but do not necessarily, refer to the same embodiment referred to in other portions of the specification. Further, when a particular aspect, feature, structure, or characteristic is described in connection with an embodiment, it is within the knowledge of one skilled in the art to affect or connect such aspect, feature, structure, or characteristic with other embodiments, whether or not explicitly described. In other words, any element or feature may be combined with any other element or feature in different embodiments, unless there is an obvious or inherent incompatibility between the two, or it is specifically excluded.

[0079] It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for the use of exclusive terminology, such as "solely," "only," and the like, in connection with the recitation of claim elements or use of a "negative" limitation. The terms “preferably,” “preferred,” “prefer,” “optionally,” “may,” and similar terms are used to indicate that an item, condition or step being referred to is an optional (not required) feature of the invention.

[0080] The singular forms "a," "an," and "the" include the plural reference unless the context clearly dictates otherwise. The term "and/or" means any one of the items, any combination of the items, or all of the items with which this term is associated. [0081] As will be understood by the skilled artisan, all numbers, including those expressing quantities of reagents or ingredients, properties such as molecular weight, reaction conditions, and so forth, are approximations and are understood as being optionally modified in all instances by the term "about." These values can vary depending upon the desired properties sought to be obtained by those skilled in the art utilizing the teachings of the descriptions herein. It is also understood that such values inherently contain variability necessarily resulting from the standard deviations found in their respective testing measurements.

[0082] The term "about" can refer to a variation of ± 5%, ± 10%, ± 20%, or ± 25% of the value specified. For example, "about 50" percent can in some embodiments carry a variation from 45 to 55 percent. For integer ranges, the term "about" can include one or two integers greater than and/or less than a recited integer at each end of the range. Unless indicated otherwise herein, the term "about" is intended to include values and ranges proximate to the recited range that are equivalent in terms of the functionality of the composition, or the embodiment.

[0083] As will be understood by one skilled in the art, for any and all purposes, particularly in terms of providing a written description, all ranges recited herein also encompass any and all possible sub-ranges and combinations of sub-ranges thereof, as well as the individual values making up the range, particularly integer values. A recited range (e.g., weight percents or carbon groups) includes each specific value, integer, decimal, or identity within the range.

Any listed range can be easily recognized as sufficiently describing and enabling the same range being broken down into at least equal halves, thirds, quarters, fifths, or tenths. As a non-limiting example, each range discussed herein can be readily broken down into a lower third, middle third and upper third, etc.

[0084] As will also be understood by one skilled in the art, all language such as "up to", "at least", "greater than", "less than", "more than", "or more", and the like, include the number recited and such terms refer to ranges that can be subsequently broken down into sub-ranges as discussed above. In the same manner, all ratios recited herein also include all sub-ratios falling within the broader ratio. Accordingly, specific values recited for radicals, substituents, and ranges, are for illustration only; they do not exclude other defined values or other values within defined ranges for radicals and substituents.

[0085] One skilled in the art will also readily recognize that where members are grouped together in a common manner, such as in a Markush group, the invention encompasses not only the entire group listed as a whole, but each member of the group individually and all possible subgroups of the main group. Additionally, for all purposes, the invention encompasses not only the main group, but also the main group absent one or more of the group members. The invention therefore envisages the explicit exclusion of any one or more of members of a recited group. Accordingly, provisos may apply to any of the disclosed categories or embodiments whereby any one or more of the recited elements, species, or embodiments, may be excluded from such categories or embodiments, for example, as used in an explicit negative limitation.

Claims

CLAIMS:

1. A solar energy collection system comprising: a) a radiation concentrator comprising a horizontally elongate parabolic reflector having a focus line; b) a heat exchanger comprising a target conduit which lies along or adjacent to the focus line of the parabolic reflector and carries a thermal fluid; and c) a subsystem configured to move the thermal fluid through the heat exchanger.

2. The system of claim 1 wherein the radiation concentrator comprises a plurality of optical panel arrays, arranged in a horizontal row.

3. The system of claim 2 wherein each optical panel array comprises a plurality of optical panels, arranged in a vertical row, wherein each optical panel has a curved reflective surface.

4. The system of any one of claims 1-3 wherein the radiation concentrator comprises a optical panel array cluster comprising a plurality of optical panel arrays, mounted on a framework of support beams, such as parabolic I-beams, a support truss, and anchoring cables.

5. The system of any one of claims 1-4, wherein the radiation concentrator is mounted on a substructure, configured to be rotatable about a horizontal axis substantially coincident with the focus line.

6. The system of claim 5 wherein the substructure comprises a base, a pivot arm which pivots about the horizontal axis, and an elbow pivot for pivotably mounting the optical panel array cluster to the pivot arm, by means of an extension arm depending from the cluster.

7. The system of claim 6 wherein the optical panel array cluster can be rotated by movement of the pivot arm and/or the elbow pivot.

8. The system of any one of claims 2-7 comprising opposing optical panel arrays, on opposing sides of the target conduit.

9. The system of any one of claims 1-8, wherein the target conduit comprises an inner exchanger conduit and an annular gap conduit, wherein the gap conduit defines a longitudinal gap which receives solar energy from the radiation concentrator, and the exchanger conduit comprises a hot pipe, a portion of which is exposed to the gap, and a cold sleeve partially surrounding the hot pipe.

10. The system of claim 9 wherein the hot pipe and cold sleeve are separated by an insulating space.

11. The system of claim 9 or 10 wherein the gap is sealed with a gap insert, comprising spaced apart ambient air tubes and a transparent window allowing passage of solar energy through the gap insert.

12. The system of claim 11 wherein the gap insert window comprises a lens for modulating the shape of solar energy passing through the gap insert.

13. The system of claim 11 or 12, wherein the ambient air tubes comprise a plurality of perforations for directing forced outside air into the gap conduit.

14. The system of claim 13 wherein each ambient air tube defines two rows of perforations, which direct air at an oblique angle into the gap conduit.

15. The system of any one of claims 9 to 14, wherein the hot pipe comprises inner guides for causing non-linear or turbulent flow of the thermal fluid within the hot pipe, preferably helical flow.

16. The system of any one of claims 9 to 15, wherein the portion of the hot pipe exposed to the gap comprises a heat transfer strip, which is preferably formed from an efficient heat conductor and/or heat absorber.

17. The system of claim 16 wherein the outer surface of the heat transfer strip is crenulated.

18. The system of any one of claims 1-17, wherein the radiation concentrator comprises a parabolic reflector having a shape consisting of a segment of a parabola taken from one side of the parabolic plane of symmetry.

19. The system of any one of claims 1-18, further comprising a control system operatively connected to means to rotate the radiation concentrator and/or means to move thermal fluid through the target conduit, and configured to;

(a) rotate the radiation concentrator in accordance with the measured or predicted elevation of the sun above the horizon; (b) rotate the target conduit along its longitudinal axis;

(c) control the flow rate of thermal fluid through the target conduit; and/or

(d) control the recycle rate of thermal fluid within the target conduit.