Parabolic trough solar collector

Abstract

A parabolic trough solar collector for concentrated solar power (CSP) applications includes a solar concentrator, a central mount to which the solar concentrator is coupled, and a receiver tube fixed at a focal point above the solar concentrator. The solar concentrator is operable to actuate relative to a single axis through the receiver tube. The surface of the solar concentrator is arranged with a fixed slope relative to a horizontal plane.

Description

[0001] PARABOLIC TROUGH SOLAR COLLECTOR

[0002] CROSS-REFERENCE TO RELATED APPLICATION

[0003] This application claims the benefit of priority of United States provisional patent application 63 / 693,631, filed 11 September 2024, the entirety of which is incorporated herein by reference.

[0004] FIELD

[0005] This disclosure relates generally to parabolic trough collectors (PTC) or parabolic trough solar collectors, and particularly to a fixed-slope single-axis parabolic trough solar collector for concentrated solar power (CSP) applications.

[0006] BACKGROUND

[0007] At present, conventional parabolic trough collectors (PTC) for concentrated solar power (CSP) applications include a receiver tube that is fixed in relation to a trough, such that both components translate rotationally about a single axis of rotation while tracking the sun. This fixed relationship results in an incident angle between solar rays and a reflective surface of the PTC, where an increased angle of incidence results in losses such as a lower thermal efficiency that is achievable by the PTC.

[0008] SUMMARY

[0009] There is thus a need in the art for PTC units that, by their construction and the use of selected materials, mitigate an incident angle between solar rays and a reflective surface of the PTC by enabling independent movement of a parabolic trough module (PTM) relative to a stationary receiver tube. The enabled independent movement effects a fixed tilt in the design of the PTC, allowing for better tracking of the reflective surface relative to the solar rays.

[0010] In an aspect of the present disclosure, a parabolic trough solar collector includes a solar concentrator, a central mount, and a heat collecting element assembly. The solar concentrator includes a truss assembly; a plurality of mirror panels coupled to the truss assembly; and at least one bearing track hoop coupled to the truss assembly. The central mount includes a pylon; a frame coupled to the pylon; and at least one set of bearings coupled to the frame, wherein the at least one set of bearings are operable to engage with the at least one bearing track hoop, and wherein the solar concentrator is actuatable relative to the central mount via the at least one bearing track hoop and the at least one set of bearings. The heat collecting element (HCE) assembly includes at least one HCE mount; and a receiver tube operable to couple to the at least HCE mount via a connector. The receiver tube is fixed at a focal length above the solar concentrator, and the solar concentrator is actuatable relative to the receiver tube via the connector.

[0011] In embodiments, the plurality of mirror panels is arranged in parabolic rows and directed toward the receiver tube fixed at the focal length above the solar concentrator. In embodiments, the plurality of mirror panels includes sixteen mirror panels arranged in four parabolic rows and four columns.

[0012] In embodiments, the at least one bearing track hoop is coupled to the truss assembly via at least one standoff. In embodiments, the at least one bearing track hoop includes a first bearing track hoop and a second bearing track hoop, and the at least one set of bearings include two sets of bearings operable to engage with the first bearing track hoop and two additional sets of bearings operable to engage with the second bearing track hoop. In embodiments, the first bearing track hoop is positioned at one-quarter of the length of the solar concentrator as measured from a first end of the parabolic trough solar collector, and the second bearing track hoop is positioned at three-quarter of the length of solar concentrators as measured from the first end.

[0013] In embodiments, the frame includes a plurality of beam segments. In embodiments, the plurality of beam segments including a first beam segment coupled to the pylon and at least a second beam segment joined to an end of the first beam segment. In embodiments, the at least one set of bearings are positioned on the at least a second beam segment.

[0014] In embodiments, the at least one bearing track hoop forms a half-circle. In embodiments, the parabolic trough solar collector further includes a motor operable to drive the at least one bearing track hoop through the at least one set of bearings. In embodiments, the connector is a bearing.

[0015] In embodiments, the receiver tube includes an absorber tube operable to hold a transfer fluid to be heated by the solar concentrator; shielding surrounding the sides of the absorber tube along at least a portion of a length of the absorber tube; and bellows at each end of the shielding, where the absorber tube is longer than the shielding such that the absorber tube extends through the bellows. In embodiments, the shielding is an evacuated glass tube, and wherein the absorber tube is a metal pipe.

[0016] In embodiments, a proximal end of the parabolic trough solar collector is increased in height as compared to a distal end of the parabolic trough solar collector relative to a horizontal plane. In embodiments, the parabolic trough solar collector is at a 33-degree angle relative to the horizonal plane in a North-South configuration, and the proximal end is aligned with North and the distal end is aligned with South. In another aspect of the present disclosure, a solar collector assembly includes a plurality of parabolic trough solar collectors; and a receiver tube assembly comprising a plurality of receiver tubes, where a receiver tube of the plurality of receiver tubes corresponds to a parabolic trough solar collector of the plurality of parabolic trough solar collectors, and where the parabolic trough solar collector is actuatable relative to the receiver tube.

[0017] In embodiments, adj acent receiver tubes of the plurality of receiver tubes are coupled together via a constituent pipe to allow a transfer fluid to pass through the plurality of receiver tubes. In embodiments, the plurality of receiver tubes is configured in a Z-shape pattern across the plurality of parabolic trough solar collectors.

[0018] In another aspect of the present disclosure, a concentrated solar plant includes a solar collector assembly; an upstream process unit operable to provide a transfer fluid to the solar collector assembly; and a downstream process unit operable to harvest heat from a heated transfer fluid received from the solar collector assembly.

[0019] While specific embodiments and applications have been illustrated and described, the present disclosure is not limited to the precise configuration and components described herein. Various modifications, changes, and variations which will be apparent to those skilled in the art may be made in the arrangement, operation, and details of the methods and systems disclosed herein without departing from the spirit and scope of the overall disclosure.

[0020] As used herein, unless otherwise specified, the terms “about,” “approximately,” etc., when used in relation to numerical limitations or ranges, mean that the recited limitation or range may vary by up to 10%. By way of non-limiting example, “about 750” can mean as little as 675 or as much as 825, or any value therebetween. When used in relation to ratios or relationships between two or more numerical limitations or ranges, the terms “about,” “approximately,” etc. mean that each of the limitations or ranges may vary by up to 10%; by way of non-limiting example, a statement that two quantities are “approximately equal” can mean that a ratio between the two quantities is as little as 0.9: 1.1 or as much as 1.1 :0.9 (or any value therebetween), and a statement that a four-way ratio is “about 5:3: 1 : 1” can mean that the first number in the ratio can be any value of at least 4.5 and no more than 5.5, the second number in the ratio can be any value of at least 2.7 and no more than 3.3, and so on. The embodiments and configurations described herein are neither complete nor exhaustive. As will be appreciated, other embodiments are possible utilizing, alone or in combination, one or more of the features set forth above or described in detail below.

[0021] BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A is a depiction of useful perpendicular and non-useful parallel components of an incident solar irradiance vector onto a reflective surface.

[0023] Figure IB is a depiction of a slope angle P required to negate cosine losses of solar irradiance onto a reflective surface.

[0024] Figure 2 is a perspective view of a rendering of a PTC array configured in series and parallel rows, according to embodiments of the present disclosure.

[0025] Figure 3A is a rendering of a parabolic trough module (PTM) operable as a standalone parabolic trough collector (PTC) with an independent support structure, according to embodiments of the present disclosure.

[0026] Figure 3B is the PTM of Figure 3 A with a receiver tube, according to embodiments of the present disclosure.

[0027] Figure 4 is a top perspective view of a rendering of mirror panel counterparts that form a section of a solar concentrator surface, according to embodiments of the present disclosure.

[0028] Figure 5 is a perspective view of a rendering of a solar concentrator of a PTM, according to embodiments of the present disclosure.

[0029] Figure 6 is a perspective view of a rendering of a solar concentrator of a PTM with partial bearing track hoops, according to embodiments of the present disclosure.

[0030] Figure 7 is a perspective view of a rendering of a central mount and positioned bearing sets, according to embodiments of the present disclosure.

[0031] Figure 8 a front elevation view of a rendering of a bearing set, according to embodiments of the present disclosure.

[0032] Figure 9 is a perspective view of an off-center position of a support pylon in relation to a central mount, according to embodiments of the present disclosure.

[0033] Figure 10 is a front elevation view of a rendering of a heat collecting element (HCE) with absorber tube, glass envelope, gutters, and seals, according to embodiments of the present disclosure.

[0034] Figure 11A is a perspective view of a rendering of a receiver tube including HCE and nominal pipe constituents, according to embodiments of the present disclosure. Figure 1 IB is a perspective view of a rendering of a PTC array configured in series and parallel rows with an assembly of receiver tubes, according to embodiments of the present disclosure.

[0035] Figure 12 is a front elevation view of a rendering of an HCE mount to secure HCE to a support infrastructure, according to embodiments of the present disclosure.

[0036] DETAILED DESCRIPTION

[0037] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as is commonly understood by one of ordinary skill in the art. All patents, applications, published applications, and other publications to which reference is made herein are incorporated by reference in their entirety. If there is a plurality of definitions for a term herein, the definition provided in the Summary prevails unless otherwise stated.

[0038] The present disclosure provides a parabolic trough solar collector for concentrated solar power (CSP) applications. In particular, the present disclosure includes a fixed-slope single axis tracking parabolic trough solar collector, or parabolic trough collector (PTC). The PTC is positioned at a fixed slope angle to mitigate cosine losses experienced in conventional PTC designs. It is understood that the optimal slope angle to fix the PTC coincides with the zenith angle that occurs at solar noon on the day of the solar equinox for a given location. This optimal slope angle, in addition to the zenith angle, corresponds to the latitude angle of the location where the PTC is to be operated. A particularity of the design of the present disclosure is associated with having a stationary and rigid receiver tube that serves as both the focal line and axis of rotation for the collector. To facilitate this action, parabolic trough modules (PTM) are combined with bearing track hoops, mounted onto a central support structure, and rotated by means of a direct drive motor. The PTC design of the present disclosure will achieve a significant reduction of cosine losses in comparison to its conventional PTC counterpart, resulting in increased optical efficiency when deployed into operation.

[0039] PTC utilized in CSP applications are a type of solar concentrating device (SCD) for concentrating solar irradiance on a focal point. By concentrating solar rays from a surface of relatively large aperture onto a surface of a relatively small diameter (i.e., the focal point), solar flux is substantially increased, relatively high local temperatures result, and an ability to exploit solar irradiance in the form of usable thermal power is achieved.

[0040] An SCD includes a solar concentrator, a heat collecting element (HCE), a support structure, and a tracking system. In the case of a PTC, a receiver tube is traditionally positioned at the focal point of the trough (e.g., positioned at the focal line (i.e. the focal point) of the parabolic concentrator over the length of the collector), where the position of the focal point is determined by the geometry of the parabolic shape selected for the design.

[0041] Traditionally, the receiver tube is fixed in relation to the trough, and both components translate rotationally about a single axis of rotation while tracking the sun. In contrast, embodiments of the present disclosure include a PTC which implements a fixed rigid receiver tube that serves as the focal point and axis of rotation for the trough, allowing the concentrator to move independently about the stationary receiver. Heat is extracted from the PTC by means of a heat transfer fluid (HTF) that circulates through the receiver tube. The useful thermal energy collected and stored within the HTF is utilized downstream of the PTC as the heat source for a power block that converts thermal power into electrical power.

[0042] Designing the PTC to establish independent movement of a PTM about a stationary receiver enables a fixed tilt. In one example, assuming a North-South orientation, a fixed tilt refers to elevating the North end of the PTC with respect to the South end. Permanently elevating the North end of the PTC results in an incline or slope over the length of the PTC with respect to horizontal. In some aspects of the present disclosure, the PTC is broken down into independent PTM that serve as standalone PTC.

[0043] The intent of tilting the PTM is to mitigate the incident angle between solar rays and the reflective surface. The larger the angle of incidence, the larger the experienced cosine losses, and, ultimately, the lower thermal efficiency that is achieved by the PTC. If the incident solar irradiance onto a reflective surface is described by a two-dimensional vector, the experienced cosine losses relate to the useful component of the vector that is perpendicular to the surface compared to the magnitude of the original vector.

[0044] As seen in Fig. 1 A, calculating the useful component of the solar irradiance vector involves taking the cosine of the incident angle and multiplying that quantity by magnitude of the original vector, or I * cos 0 = Z±, where Z is the magnitude of the original vector, 0 is the incident angle, and Z±is the useful component of the vector. As shown in Fig. 1 A, Z is the non-useful component of the vector. An incident angle between a reflector and incident solar rays of 0 degrees (°), 10°, 20°, 30°, 50° would result in estimated cosine losses of 0.0%, 1.5%, 6.3%, 13.3%, and 35.7%, respectively.

[0045] Cosine losses, which can have a significant impact on optical efficiency, may be mitigated by reducing the incident angle of solar radiation on the PTC reflective surface. Mitigation of the incident angle between incoming solar rays and the PTC surface is the rationale behind sloping the collector. As seen in Fig. IB, tilting the reflective surface with respect to horizontal by angle 5 can negate the angle of incidence and reduce the parallel i.e., non-useful, component of the irradiance vector to zero.

[0046] The local solar zenith angle is also a consideration when determining the optimal permanent slope for the PTC. The local solar zenith angle is measured by taking the angle between the direction of incoming solar rays and the vertical direction. This local zenith angle varies throughout a daily solar cycle, as well as on a seasonal basis. With consideration that the slope of the PTC will be fixed despite seasonal and daily variations of the zenith angle, the average local zenith angle is utilized to derive an optimal slope angle. The average zenith angle for any given location is equivalent to that experienced during the solar equinox.

[0047] Due to the dynamics of single-axis solar tracking with the design of the present disclosure, the slope of the PTC is most effective at mitigating cosine losses at solar noon when the sun is directly South and at its highest point in the sky (assuming a North-South configuration). Therefore, the fixed slope angle of the PTC corresponds with the local zenith angle at solar noon to optimize optical efficiency, which coincides with the latitude angle of the location being analyzed. With geometric reasoning, it can be realized that the local zenith angle equates to the slope angle i.e., angle 5, necessary to obtain an incident angle equal to zero. This embodiment of the proposed design assumes a site location at a latitude of 33° N. As such, it is contemplated that an optimal slope angle to permanently fix the solar collectors is 33°.

[0048] Fig. 2 illustrates a solar collector assembly 100 (SCA 100) that includes a plurality of parabolic trough modules (PTM) 102, according to embodiments of the present disclosure. In some embodiments, the SCA 100 can include 1, 2, ... N PTMs 102, where N is any positive integer. As illustrated in Fig. 3, a row of PTM 102 is considered a parabolic trough collector (PTC) 104. Multiple parallel PTC 104 can be connected in series of parallel rows (oriented on a fixed North-South axis), with respect to the circulation of HTF, to form the SCA 100. It is contemplated that arranging the PTM 102 in the configuration shown in Fig. 2 allows for similar results to traditional SCA known in the art.

[0049] Figs. 3 A and 3B illustrates a single PTM 102 that serves as a standalone PTC, according to embodiments of the present disclosure. One benefit of a single PTM 102 serving as a standalone PTC is the accommodation of elevation differentials. Fixing a traditional SCA at a 33° slope typically presents a structural challenge due to a significant elevation differential from the South end to the North end of the PTC that comprise the SCA, as the individual PTM are coincident to the preceding and proceeding troughs. In one example, arranging the PTC in the coincident trough configuration with the PTC fixed at a 33° tilt would require a 54-meter (m) elevation increase from the South to the North ends of the traditional SCA, which would be impractical in terms of designing the support structure. Instead, the standalone configuration of Fig. 3 allows for the height differential between preceding and proceeding ends of the troughs of individual PTM 102 in the SCA 100, as illustrated in Fig. 2.

[0050] As illustrated in Figs. 3 A and 3B, the PTM 102 includes a solar concentrator 106, a central mount 108, and a heat collecting element (HCE) assembly 110. The solar concentrator 106 is supported by the central mount 108 and is configured to rotate about an axis of rotation 118 through the HCE assembly 110. Although not shown, the HCE assembly 110 is operable to receive a receiver tube 168 via HCE mounts 180, where the receiver tube 168 is positioned at the axis of rotation 118.

[0051] Figs. 4-6 illustrate the solar concentrator 106 of the PTM 102, according to embodiments of the present disclosure. The solar concentrator 106 includes a plurality of mirror panels 112 that form a solar concentrator surface 114. In some embodiments, the plurality of mirror panels 112 include 1, 2, ... N mirror panels 112, where N is any positive integer. In one non-limiting example, the mirror panels 112 are formed from a low iron float glass with silver backing. In another non-limiting example, the mirror panels 112 are 4 millimeters (mm) thick. It is noted, however, that the mirror panels 112 are not limited to 4 mm thickness. In general, the mirror panels 112 can be any thickness that is sufficient to accommodate induced stresses while not impeding the reflective quality of the panels 112, without departing from the scope of the present disclosure.

[0052] Referring now to Fig. 4, an example solar concentrator surface 114 includes mirror panels 112A-112D with respective mirror surfaces 116A-116D. As illustrated in Fig. 4 (and Fig. 3), the mirror panels 112A-112D are concave inward toward the central axis 118. The mirror surfaces 116A-116D have a select curvature, such that the solar concentrator surface 114 forms a parabolic heat concentrating surface that reflects solar rays 120 to the central axis 118. In some embodiments, the mirror panels 112 are fabricated with molds in an oven to ensure a permanent and accurate parabolic shape across the solar concentrator surface 114. It is noted herein the mirrors panels 112A-112D may be considered within a parabolic row 122.

[0053] In one non-limiting example, the solar concentrator surface 114 has a 5.76 m aperture and a 1.71 m focal length (e.g., at which the central axis 118 is positioned). In this non-limiting example, the solar concentrator 106 may have a 94% overall reflectivity in which 97% of all reflective rays 120 fall incident onto a receiver tube (not shown).

[0054] As illustrated in Figs. 5-6, the plurality of mirror panels 112 are arranged in a set of parabolic rows 122 and columns 124. In some embodiments, the rows 122 and / or columns 124 include 1, 2, . . . N rows 122 and / or columns 124, respectively, where N is any positive integer. In one non-limiting example, the solar concentrator 106 includes 16 mirror panels 112 arranged in 4 rows 122 and 4 columns 124. In another non-limiting example, the PTM 102 has an overall length of approximately 7 m.

[0055] In some embodiments, adjacent mirror panels 112 are separated by a gap (e.g., to allow rain, etc. to flow between the mirror panels 112). In other embodiments, adjacent mirror panels abut against one another in a non-interfering manner, such that a gap is not present. It is noted herein that gaskets or sealant able to withstand the operating temperature of the solar concentrator surface 114 may be positioned between adjacent mirror panels 112 to fill a gap but allow for shifting or adjustment of the mirror panels 112.

[0056] The plurality of mirror panels 112 are coupled to a truss assembly (or truss infrastructure) 126. The truss assembly 126 includes a plurality of truss members arranged in a select configuration. In some embodiments, the plurality of truss members includes 1, 2, ... N truss members arranged in any configuration, where N is any positive integer. In one non-limiting example, the truss assembly 126 includes a top chord 130 and bottom chord 132, with webs 134 set at a non-zero angle between 0° and 180° coupled therebetween. In another non-limiting example, the truss assembly 126 includes posts 136 and / or ties 138 between the top chord 130 and the bottom chord 132. For instance, the posts 136 may be perpendicular or substantially perpendicular to the top chord 130 and / or the bottom chord 132 in a first orthogonal direction. In addition, the ties 138 may be perpendicular or substantially perpendicular to the top chord 130 and / or the bottom chord 132 in a second, different orthogonal direction. Fig. 5 illustrates an example set of orthogonal axes.

[0057] In embodiments, the truss assembly 126 includes or is configured to couple to an end plate 140. The end plate 140 may be fabricated from a solid piece of material or may include truss-like elements similar to those listed above with respect to the truss assembly 126. In one non-limiting example, at least a portion 142 of the end plate 140 extends above the solar concentrator surface 114. In this example, as illustrated in Fig. 3, the portion 142 may be positioned at a proximal end or edge of the solar concentrator 106. In the instance where the PTM 102 is in a North-South configuration, “proximal” may refer to the raised North end or edge, and “distal” may refer to the lowered South end or edge of the PTM 102. It is noted that the portion 142 may be used for positioning or securing counterweights to the solar concentrator 106, as an additional location for tie-downs or receiver tube assemblies, or other uses that may require a bracket or grounded structure connected to the truss assembly 126.

[0058] Ceramic pads 144 on a rear surface of the mirror panels 112 form a connection (e.g., physical, thermal, electrical, or the like) between the mirror panels 112 and the truss assembly 126. In some embodiments, the ceramic pads 144 include 1, 2, ... N ceramic pads 144, where N is any positive integer. The ceramic pads 144 may be the direct points of contact between the mirror panels 112 and the truss assembly 126, or may be positioned on or between brackets that extend upward from the truss assembly 126. The ceramic pads 144 may have relatively high thermal resistivity and compressive strength and may serve as a form of insulation between the mirror panels 112 and the truss assembly 126. The primary physical characteristics necessary for material selection of the ceramic components are compressive strength and heat conductivity. These physical qualities should be sufficient to meet the expected loads and stresses experienced by applicable components of the PTM 102 within an appropriate safety margin and provide a desired heat loss efficiency, respectively. Other considerations may include, but are not limited to, the thermal expansion and thermal stresses of the material across the entire range of temperatures between ambient temperatures and operating temperatures. Those of ordinary skill in the art will understand and appreciate how to select an appropriate ceramic material for a desired application based on consideration of these and other factors.

[0059] To achieve rotation of the PTM 102 about a receiver tube (not shown), which represents or is positioned at an axis of rotation for the PTM 102, the solar concentrator 106 includes partial bearing track hoops 146 coupled to the truss assembly 126 via standoffs 148. In some embodiments, the partial track hoops 146 include 1, 2, . . . N partial track hoops 146, and / or the standoffs 148 includes 1, 2, ... M standoffs 148, where N and / or M is any positive integer. The standoffs 148 may be integrated within the truss assembly 126 (e.g., are extensions of elements such as posts 136 as described herein). Alternatively, or in addition, the standoffs 148 may be coupled to the truss assembly 126. In one non-limiting example, the standoffs 148 are located at positions of one-quarter (%) and three-quarter (%) of the length (e.g., along the y-axis as illustrated in Fig. 5) of the solar concentrator 106.

[0060] In embodiments, track hoops 146 extend upward above the solar concentrator surface 114. In this example, the parabolic solar concentrator surface 114 forms an arc having an angle of between 90° and 180°, whereas the track hoops 146 forms a half-circle of 180° (or approximately 180°). In one non-limiting example, the bearing track hoops 146 are fabricated from square steel tubing. In another non-limiting example, the bearing track hoops 146 are bent into a 6 m diameter half-circle.

[0061] Figs. 7-9 illustrate the central mount 108 of the PTM 102, according to embodiments of the present disclosure. The central mount 108 is operable to support the PTM 102 as a standalone PTC. In some embodiments, the central mount 108 fixes the PTM 102 at a desired 33° angle in the North-South configuration (e.g., where the PTM 102 forms a 33° angle with a horizontal plane, with the North end or edge being higher than the South end or edge).

[0062] Referring now to Fig. 7, the central mount 108 includes a pylon 148, a frame 150 with beam segments 152, and one or more sets of bearings 154. In some embodiments, the beam segments 152 include 1, 2, ... N beam segments 152, and / or the sets of bearings 154 include 1, 2, ... M sets of bearings 154, where N and / or M is any positive integer. In general, the beam segments 152 may include any known cross-section without departing from the scope of the present disclosure. One exemplary cross-section for the beam segments 152 is an I-beam cross section.

[0063] In one non-limiting example, the pylon 148 may be a flat bottom cylindrical tube that extends from a concrete caisson (not shown) to which it is coupled (e.g., via fasteners, by being inserted within the caisson, or the like). To angle the solar concentrator 106, the top end of the pylon 148 may cut at an angle. For example, the angle may be a 33° angle oriented in a North-South direction with respect to a horizontal plane.

[0064] The angled top end of the pylon 148 is operable to receive and / or be coupled to a lower flat face 156 of a beam segment 152. In some examples, the beam segments 152 are I-beams, and a lower flat face 156 of a leg of the I-beam is positioned on the angled top end of the pylon 148. In these examples, the width of the flat face of the leg of the I-beam may be substantially similar to a diameter or width of the angled top end of the pylon 148, such that the edges of the I-beam leg 152 and the pylon 148 are coincident and coupled together (e.g., via fasteners, welds, or the like). Sets of bearings 154 are positioned on an upper flat face 158 of the I-beam segments 152, and are operable to receive and / or engage with (e.g., guide) the bearing track hoops 146 (as illustrated in Fig. 9) to facilitate rotational movement of the solar concentrator 106 about the receiver tube (not shown).

[0065] In some embodiments, the central mount 108 may include three I-beam segments 152, where a lower flat face 156 of a first I-beam segment 152 is coupled to the angled top end of the pylon 148, and the second and third I-beam segments 152 are joined to the proximal and distal ends, respectively of the first I-beam segment 152. Here, the three I- beam segments 152 form a I-shape, with the main body of the “I” running the length of the solar concentrator 106 and the legs of the I-shape extending laterally from the main body to support the lateral portions of the solar concentrator 106.

[0066] In the above embodiments, four sets of bearings 154 are positioned at the lateral ends of the upper flat face 158 of the second and third I-beam segments 152, with one set of bearings 154 positioned at each of the four lateral ends. The first I-beam segment 152 (or main body) may be of a length that the second and third I-beam segments 152 are proximate to the bearing track hoops 146 (e.g., as shown in Fig. 9), such that two sets of bearings 154 engage the more proximal first bearing track hoop 146 and two additional sets of bearings 154 engage the more distal bearing track hoop 146.

[0067] It is noted herein, however, that additional beam segments 152 may extend from the main body, with additional bearings 154 that correspond to additional bearing track hoops 146, without departing from the scope of the present disclosure. In addition, it is noted that the PTM 102 may include a single beam segment 152 coupled to the pylon 102, with a single set of bearings 154 for a single bearing track roller 146, without departing from the scope of the present disclosure.

[0068] Referring now to Fig. 8, each set of bearings 154 includes roller bearings 160. In some embodiments, the roller bearings 160 include 1, 2, ... N roller bearings 160, where N is any positive integer. For example, three roller bearings 160 may be set in a plane 161, with two being vertically oriented and one horizontally oriented. In this example, a top edge 162 of the horizontally oriented roller bearing 160 may be coincident or aligned with the bottom edges 164 of the vertically oriented roller bearings 160. The spacing between the roller bearings 160 is sufficient to receive and contact surfaces (e.g., exterior surfaces) of the bearing track hoops 146, allowing for the bearing track hoop 146 (and thus the solar concentrator 106) to actuate relative to the central mount 108.

[0069] It is noted that the surfaces of the bearing track hoops 146 may include teeth or other interlocking components that correspond to a drive system installed on the central mount 108. The drive system is usable to achieve accurate solar tracking throughout a daily cycle. The drive system may include a motor 166 that rotates a geared shaft able to engage with exposed teeth of the surfaces of the bearing track hoops 146. For example, there may be a single motor 166 that drives all the bearing track hoops 146, some of the bearing track hoops 146, or a particular individual bearing track hoop 146. As the geared shaft of the motor 166 rotates, each bearing track hoop 146 is actuated while being guided by the respective sets of bearings 154. Increased precision of the actuation can be achieved by increasing the frequency and abundance of teeth present on the bearing track hoop 146.

[0070] Referring now to Fig. 9, the PTM 102 is illustrated with the solar concentrator 106 rotated to a lateral end of the bearing track hoops 146 after actuating through the bearings 154. From this position of the solar concentrator 106, the placement of the pylon 148 of the central mount 106 is not centered on the I-beam segment 152 that is coupled to the pylon 148. Instead, the solar concentrator 106 and the beam segments 152 are positioned relative to the pylon 148 such that the position of the pylon 148 coincides with the center of mass for the PTM 102. This allows for the use of a single pylon 148, reducing cost and increasing the ability to position the PTM 102 on a particular ground surface (e.g., as opposed to where multiple pylons 148 are used, which may constrain the options for the positioning of the pylons 148 on a ground surface).

[0071] Although not illustrated, the pylon 148 (and / or the central mount 108 in general) may include one or more secondary support members (e.g., “feet” or “legs”) that extend from the pylon 148 and / or from the frame 150, without departing from the scope of the present disclosure.

[0072] Figs. 10-12 illustrate the HCE assembly 110 of the PTM 102, according to embodiments of the present disclosure. The HCE assembly 110 is operable to couple to the truss assembly 126 of the solar concentrator 106.

[0073] Referring now to Fig. 10, the HCE assembly 110 includes one or more receiver tubes 168. In some embodiments, the receiver tubes 168 include 1, 2, ... N receiver tubes 168, where N is any positive integer. The receiver tube 168 includes an absorber tube 170 enclosed in evacuated shielding 172, where the shielding surrounds the sides of the absorber tube 170 along at least a portion of a length of the absorber tube 170. For example, the absorber tube 170 is a metal pipe, and the evacuated shielding 172 is an evacuated glass tube. Both the absorber tube 170 and the shielding 172 have a coating that improves the obtainable performance in respective roles. For example, the shielding 172 is coated with an antireflective finish on both the interior and exterior surfaces, which curtails the magnitude of radiation reflected by the glass that would otherwise be incident on the absorber tube 170. By way of another example, the absorber tube 170 is coated in a cermet material (e.g., a material from a class of heat-resistant materials made of ceramic and sintered metal) with selective heat transfer properties that significantly increase the absorptivity of solar radiation incident on the absorber tube 170 and improve the heat transfer to an HTF within the absorber tube 170. Bellows 174 on either end of the shielding 172 allow for a hermetic seal between the absorber tube 170 the shielding 172, including where the absorber tube 170 is longer than the shielding 172 and extends through the bellows 174, by accommodating the expansion and contraction that the absorber tube 170 undergoes due to extreme temperature differentials experienced over a daily cycle. In some embodiments, gutters may be placed on the inner surface of the shielding 172. For example, the gutters may absorb gases that infiltrate the vacuum within the evacuated shielding 172.

[0074] In selecting an appropriate HTF, the physical characteristics of the selected transfer fluid should be sufficient to deliver thermal energy to upstream and / or downstream processes within a thermal system of (or including) the SC A 100. Specifically, special consideration should be given to physical properties of the selected transfer fluid such as heat capacity, thermal conductivity, viscosity, and saturation pressures across the expected operating conditions of the thermal system. In some embodiments, to ensure that the transfer fluid remains in the liquid phase across the entire range of temperatures encountered in the system, the transfer fluid may be pressurized. Those of ordinary skill in the art will understand and appreciate how to select an appropriate transfer fluid for a desired application based on consideration of these and other factors.

[0075] Referring now to Figs. 11A-11B, the receiver tubes 168 may be configured in a receiver tube assembly 176 that connects adjacent PTM 102. Within the receiver tube assembly 176, adjacent receiver tubes 168 may connect to (or with) a pipe constituent 178. Due to the nature of PTM 102 being set at a fixed tilt along a North-South oriented axis, intermediate sections of receiver tube 168 in between each PTM 102 may be perpendicular, and therefore not coincident, with the focal line of the PTM 102. The receiver tube assembly 176 thus includes receiver tubes 168 in a repeating Z-shape pattern (although any pattern may be used, without departing from the scope of the present disclosure). To reduce material costs, the intermediate perpendicular segments of the receiver tube assembly 176 that do not receive concentrated solar radiation may be a noncoated continuation of the metal pipe that comprises the absorber tube 170.

[0076] A depiction of the receiver tube assembly 176 including the receiver tubes 168 and the pipe constituents 178 is seen in Fig. 11 A, and a positioning of the receiver tube assembly 176 is illustrated relative to the SCA 100 in Fig. 1 IB. Although not shown, it is contemplated that the receiver tube assembly 176 may be a closed recirculating loop, where the transfer fluid is transported to downstream process units that harvest or utilize the thermal energy after the transfer fluid is heated by the SC A 100 and / or to upstream process units that cool the transfer fluid before being returned to the receiver tubes 168.

[0077] The rigid, stationary characteristics of the receiver tubes 168 within the receiver tube assembly 176 relative to the PTM 102 are implemented to address known issues with existing solar concentrator designs. To facilitate the translation of the receiver tube 168 along with the PTC 104 involves points in which the receiver tube 168 traditionally has the ability to pivot, particularly at a junction at either end of the PTC 104 where the receiver tube 168 connects with the upstream and downstream PTM 102 and the HTF running through the respective receiver tubes 168. However, during prolonged operation, these dynamic junctions proved susceptible to notable leakage. The leakage at these failure points leads to additional operation and maintenance costs to maintain the liquid volumes of HTF within the closed recirculating loop through the receiver tube assembly 176, as well as a contribution to additional heat loss. By replacing these connections with standard rigid bends (e.g., elbows, etc.) as illustrated in the present disclosure, mitigation of fluid and heat losses into the surrounding environment is achieved.

[0078] Referring now to Fig. 12, the HCE assembly 110 includes one or more HCE mounts 180. In some embodiments, the HCE mounts 180 include 1, 2, ... N HCE mounts 180, where N is any positive integer. The HCE mounts 180 support the one (or more) receiver tubes 170 for each PTM 102, positioning the receiver tubes 168 relative to the solar concentrator surface 114 so that it maintains coincidence with the focal line of the solar concentrator 106. The HCE mounts 180 includes clamps 182 that engage the truss assembly 126 of the solar concentrator 106 (e.g., as shown in Fig. 3). HCE supports 184 coupled to the clamps 182 extend through spaces between the mirror panels 112 of the solar concentrator 106 to a focal point, and a connector 186 is positioned at the focal point of each HCE mount 180. The connector 186 may include, but is not limited to, a bearing or other non-interfering bracket that is operable to engage the receiver tube 168 and allow for independent movement of the solar concentrator 106 relative to the receiver tube 168 about an axis through the connector 186. In this regard, the receiver tube 168 (and thus the receiver tube assembly 176) may remain in a fixed position, while the solar concentrator 106 can actuate relative to the central mount 108 and rotate about the respective receiver tubes 168 via the bearing track hoops 146.

[0079] In general, at least some structural components of the SC A 100 (e.g., the PTM 102 including the solar concentrator 106, the central mount 108, the HCE assembly 110, and components thereof; the receiver tube assembly 176 and components thereof; etc.) may comprise the same or similar materials to provide consistent degrees of structural integrity throughout the SC A 100. By way of non-limiting example, at least some structural components of the SC A 100 may be constructed entirely or primarily from materials that provide corrosion resistance (e.g., caused by weather, etc.) and sufficient tensile and yield strengths under the operating conditions of the SCA 100.

[0080] In general, it is to be expressly understood that any dimensions and design and materials choices described throughout the present disclosure with respect to the SCA 100 are exemplary and illustrative only; that changes, modifications, and variations to these dimensions and design and materials choices may be possible and desirable in certain embodiments and applications; and that such changes, modifications, and variations will be understood and appreciated by those of ordinary skill in the art and are therefore within the scope of the present disclosure.

[0081] The present disclosure also includes a concentrated solar plant (CSP). The CSP includes the SCA 100 as described throughout the present disclosure, one or more upstream process units operable to provide transfer fluid to the SCA 100, and one or more downstream process units operable to receive heated transfer fluid from the SCA 100 and harvest thermal energy from the heated transfer fluid. The CSP optionally includes recirculation process units to cool and recirculate the transfer fluid to the SCA 100 via the upstream process units following the harvesting of the thermal energy via the downstream process units from the heated transfer fluid received from the SCA 100.

[0082] The present disclosure also provides methods for assembling components of the SCA 100 (e.g., the PTM 102 including the solar concentrator 106, the central mount 108, the HCE assembly 110, and components thereof; the receiver tube assembly 176 and components thereof; etc.), which may be manufactured by any suitable devices, methods, and systems known to those skilled in the art, into the SCA 100. The methods for assembling may include, but are not limited to, fabricating the central mount 108 with the pylon 148, frame 150, sets of bearings 154, and drive system including motors 166; installing the pylon 148 and / or the central mount 108 within a ground surface; fabricating the solar concentrator 106 including the truss assembly 126 and the plurality of mirror panels 112; coupling the solar concentrator 106 to the central mount 108; coupling the HCE mount assembly 110 to the solar concentrator 106; coupling the receiver tube 168 to the HCE mount assembly 110 to form the PTM 102; and / or coupling adjacent receiver tubes 168 of adjacent PTM 102 together via constituent tubes 178. The present disclosure also provides methods for operating the SC A 100. The methods for using may include, but are not limited to, setting the solar concentrator 106 at a first position relative to the receiver tube 168 at a first time within a daily cycle; setting the solar concentrator 106 at a second position relative to the receiver tube 168 at a second time within a daily cycle; ... up to setting the solar concentrator 106 at a Nth position relative to the receiver tube 168 at a Nth time within a daily cycle, where N is any positive integer; circulating heated transfer fluid from the receiver tube 168 to one or more downstream processes; and / or circulating cooled transfer fluid from one or more upstream processes to the receiver tube 168.

[0083] It is noted herein the solar concentrator 106 may be manually actuated by an operator relative to the receiver tube 168. In addition, it is noted herein the SCA 100 may include a tracking system and / or control system for the SCA 100. The components of the tracking system and / or control system may be coupled to the SCA 100 (e.g., to the drive system including motor 166) via wired connections and / or via wireless connections.

[0084] The control system may include one or more control units (e.g., a controller, server, or the like). The one or more control units may include processors and memory (e.g., a memory medium, memory device, or the like). The processors may be configured to execute program instructions maintained on or stored in the memory. The processor of the one or more control units may execute any of the various method or process steps necessary to operate the SCA 100 and / or the CSP.

[0085] The control system may include a user interface coupled (e.g., physically coupled, electrically coupled, communicatively coupled, or the like) to the one or more control units. For example, the user interface may be a separate device coupled to the one or more control units. By way of another example, the user interface and the one or more control units may be located within a common or shared housing. The user interface may include one or more displays, one or more user input devices, and / or one or more port connectors (e.g., for the transmitting and / or receiving of power and / or data, and the like).

[0086] The control system may include one or more sensors coupled (e.g., physically coupled, electrically coupled, communicatively coupled, or the like) to or integrated in the one or more control units, the SCA 100, and / or the and / or the CSP. The one or more sensors may be operable to determine various operational, physical, and / or environmental parameters of the SCA 100, the CSP, and / or the control system; the environment surrounding the SCA 100, the CSP, and / or the control system, and the like. For instance, the sensors may be operable to determine the location of the sun and adjust the positioning of the solar concentrator 106 relative to the receiver tube 168 based on the location of the sun. In addition, the sensors may be operable to determine the temperature of the heated transfer fluid within the receiver tube 168 and / or elsewhere in the connected thermal system.

[0087] The control system may include one or more transmitters and / or receivers coupled (e.g., physically coupled, electrically coupled, communicatively coupled, or the like) to or integrated in the one or more control units, the SC A 100, and / or the CSP. The one or more transmitters and / or receivers may be configured to transmit data to and / or receive data from the SCA 100 and / or the CSP (e.g., from sensors installed within the SCA 100 and / or the CSP) or from external third-party control units (e.g., controllers, servers, or the like) either via wired connections or wireless connections, which may be configured as transmitting (Tx) units, receiving (Rx) units, or combination Tx / Rx units.

[0088] The control system may be configured to monitor the SCA 100 and / or the CSP via received and / or transmitted data. The control system may be configured to generate control signals to adjust one or more components of the SCA 100 and / or the CSP via a feedback loop or a feed forward loop based on the received and / or transmitted data. The control system may be configured to receive and / or transmit data in a standardized format and / or a non-standardized format. Where the data is in a non- standard! zed format, the data may be converted to a standardized format upon receipt and / or prior to transmission to sensors, third-party control units, or the like.

[0089] The control system may assist in the manual actuation of the solar concentrator 106. Alternatively, or in addition, the control system may automatically actuate the solar concentrator 106 based on pre-set program instructions, based on data received from sensor (e.g., regarding the positioning of the sun), and the like. In this regard, thermal efficiency may be optimized by reducing cosine losses caused by an improperly-positioned or angled solar concentrator 106.

[0090] The concepts illustratively disclosed herein suitably may be practiced in the absence of any element which is not specifically disclosed herein. It is apparent to those skilled in the art, however, that many changes, variations, modifications, other uses, and applications of the disclosure are possible, and changes, variations, modifications, other uses, and applications which do not depart from the spirit and scope of the disclosure are deemed to be covered by the disclosure.

[0091] The foregoing discussion has been presented for purposes of illustration and description. The foregoing is not intended to limit the disclosure to the form or forms disclosed herein. In the foregoing Detailed Description, for example, various features are grouped together in one or more embodiments for the purpose of streamlining the disclosure. The features of the embodiments may be combined in alternate embodiments other than those discussed above. This method of disclosure is not to be interpreted as reflecting an intention that the claims require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the following claims are hereby incorporated into this Detailed Description, with each claim standing on its own as a separate embodiment.

[0092] Moreover, though the present disclosure has included description of one or more embodiments and certain variations and modifications, other variations, combinations, and modifications are within the scope of the disclosure, e.g., as may be within the skill and knowledge of those in the art, after understanding the present disclosure. It is intended to obtain rights which include alternative embodiments to the extent permitted, including alternate, interchangeable, and / or equivalent structures, functions, ranges, or steps to those claimed, regardless of whether such alternate, interchangeable, and / or equivalent structures, functions, ranges, or steps are disclosed herein, and without intending to publicly dedicate any patentable subject matter.

Claims

CLAIMSWhat is claimed is:

1. A parabolic trough solar collector, comprising: a solar concentrator comprising: a truss assembly; a plurality of mirror panels coupled to the truss assembly; and at least one bearing track hoop coupled to the truss assembly; a central mount comprising: a pylon; a frame coupled to the pylon; and at least one set of bearings coupled to the frame, wherein the at least one set of bearings are operable to engage with the at least one bearing track hoop, and wherein the solar concentrator is actuatable relative to the central mount via the at least one bearing track hoop and the at least one set of bearings; and a heat collecting element (HCE) assembly, comprising: at least one HCE mount; and a receiver tube operable to couple to the at least HCE mount via a connector, wherein the receiver tube is fixed at a focal length above the solar concentrator, and wherein the solar concentrator is actuatable relative to the receiver tube via the connector.

2. The parabolic trough solar collector of claim 1, wherein the plurality of mirror panels is arranged in parabolic rows and directed toward the receiver tube fixed at the focal length above the solar concentrator.

3. The parabolic trough solar collector of claim 2, wherein the plurality of mirror panels includes sixteen mirror panels arranged in four parabolic rows and four columns.

4. The parabolic trough solar collector of any one of claims 1-3, wherein the at least one bearing track hoop is coupled to the truss assembly via at least one standoff.

5. The parabolic trough solar collector of any one of claims 1-4, wherein the at least one bearing track hoop includes a first bearing track hoop and a second bearing track hoop, and wherein the at least one set of bearings include two sets of bearings operable to engage with the first bearing track hoop and two additional sets of bearings operable to engage with the second bearing track hoop.

6. The parabolic trough solar collector of claim 5, wherein the first bearing track hoop is positioned at one-quarter of the length of the solar concentrator as measured from a first end of the parabolic trough solar collector, and wherein the second bearing track hoop is positioned at three-quarter of the length of solar concentrators as measured from the first end.

7. The parabolic trough solar collector of any one of claims 1-6, wherein the frame includes a plurality of beam segments.

8. The parabolic trough solar collector of claim 7, wherein the plurality of beam segments including a first beam segment coupled to the pylon and at least a second beam segment joined to an end of the first beam segment.

9. The parabolic trough solar collector of claim 8, wherein the at least one set of bearings are positioned on the at least a second beam segment.

10. The parabolic trough solar collector of any one of claims 1-9, wherein the at least one bearing track hoop forms a half-circle.

11. The parabolic trough solar collector of any one of claims 1-10, further comprising a motor operable to drive the at least one bearing track hoop through the at least one set of bearings.

12. The parabolic trough solar collector of any one of claims 1-11, wherein the connector is a bearing.

13. The parabolic trough solar collector of any one of claims 1-12, wherein the receiver tube comprises: an absorber tube operable to hold a transfer fluid to be heated by the solar concentrator; shielding surrounding the sides of the absorber tube along at least a portion of a length of the absorber tube; and bellows at each end of the shielding, wherein the absorber tube is longer than the shielding such that the absorber tube extends through the bellows.

14. The parabolic trough solar collector of claim 13, wherein the shielding is an evacuated glass tube, and wherein the absorber tube is a metal pipe.

15. The parabolic trough solar collector of any one of claims 1-14, wherein a proximal end of the parabolic trough solar collector is increased in height as compared to a distal end of the parabolic trough solar collector relative to a horizontal plane.

16. The parabolic trough solar collector of claim 15, wherein the parabolic trough solar collector is at a 33-degree angle relative to the horizonal plane in a North-South configuration, and wherein the proximal end is aligned with North and the distal end is aligned with South.

17. A solar collector assembly, comprising: a plurality of parabolic trough solar collectors; and a receiver tube assembly comprising a plurality of receiver tubes, wherein a receiver tube of the plurality of receiver tubes corresponds to a parabolic trough solar collector of the plurality of parabolic trough solar collectors, and wherein the parabolic trough solar collector is actuatable relative to the receiver tube.

18. The solar collector assembly of claim 17, wherein adjacent receiver tubes of the plurality of receiver tubes are coupled together via a constituent pipe to allow a transfer fluid to pass through the plurality of receiver tubes.

19. The solar collector assembly of claim 18, wherein the plurality of receiver tubes is configured in a Z-shape pattern across the plurality of parabolic trough solar collectors.

20. A concentrated solar plant, comprising: a solar collector assembly; an upstream process unit operable to provide a transfer fluid to the solar collector assembly; and a downstream process unit operable to harvest heat from a heated transfer fluid received from the solar collector assembly.

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