Abstract:
A solar concentrating collector includes corrugated board parabolic support segments with flexible strips and side tabs over the cut edge to support a laminate with reflective coated film. The reflector assembly has supporting arms and pivots about a heat absorbing conduit secured to vertical extensions of adjacent stationary posts. Selected external surfaces are weatherproofed. The conduit includes vacuum insulators and means to isolate conduit from insulator expansion. Upper arms support pulleys and cable take-ups for continuous collector position changes. Cross members of the extended post secure the fixed conduit, and at a higher level, a programmable drive to rotate two cable capstans for cables that pivot two adjacent reflector assemblies. Other embodiments include triangular or square fluid conduits with planar surfaces for photovoltaic cells and a modified reflective surface to disperse solar rays into a band of reflected sunlight directed to photocell areas.

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
   The use of linear parabolic reflector troughs for concentrating solar rays on a heat collector pipe is well known. Prior collector systems for heating fluids to generate power depend from and use many of the same components as systems going back 40 or more years. 
   Several current “state of the art” solar energy generating plants (SEGS) ranging from 30 to 320 megawatts are operating in the Mojave desert of California. The collectors include spaced parabolic truss supports extending transversely from about 6 to 18 ft wide. Collector systems heat fluids from 560 degrees to over 700 degrees F., and all use trusses extending outward from a pivoting central structure or tube, to support cast linear parabolic shaped mirrors to form the trough. 
   Current parabolic mirror reflectors and trusses together with the attached absorber conduit are pivoted about a central structure or tube using hydraulic actuators and speed reduction gear boxes. 
   The reflected rays are focused on a metallic pipe of extended length enclosed within a vacuumized glass tube of equal length. 
   Current designs have inherent cost and maintenance problems which together with the cyclic nature of the sun (including cloudy days) prevents solar power generating plants from producing cost effective power available around the clock. To mitigate these limitations, solar heat and natural gas power generation were used in a “combined cycle” system on some of the SEG plants. 
   Aside from cost and operating differences, the combined cycle plant still had CO2 emissions and is subject to fossil fuel price fluctuations or supply disruptions. 
   Generally, all solar collector power systems perform the same functions and require the same basic components including a parabolic reflector to focus solar rays on a heat absorbing conduit. Other components added to increase conversion efficiency include means to continuously pivot the reflector as the sun moves from east to west and the vacuumzed glass tube surrounding the heat absorbing pipe to reduce emissive heat loss to ambient air. 
   Because of the gradient from ambient temperature to maximum, the difference in expansion of the glass tube and absorber pipe in current SEG designs requires an “expansion bellows” between sections of conduit and are prone to leakage and loss of vacuum. Components of the invention lower emission heat loss and vacuum leakage. 
   The instant collector system of this invention relies on basic components disclosed in current systems, but due to substantial weight reduction uses downwardly extending arms to suspend the reflector panel for pivoting about a fixed absorber conduit supported from simplified panel supports at both ends, 
   The instant collector system counters the difference in expansion of pipe and enclosing glass by eliminating bellows of current designs and using a plurality of conduit insulators comprised of two concentric tubes sealed at the ends to define a vacuum space. Insulators are separated by resilient compression springs to allow for insulator expansion independent from expansion of the pipe. The insulator has central openings and surrounds the pipe. Supports for the fixed conduit and a suspended reflector panel are simplified because of weight reduction. 
   Prior art U.S. Pat. No. 4,416,263 described transversely aligned parabolic segments supported on a truss sub-base structure. The instant collector uses similar parabolic segments combined with other corrugated board members to define a unitary structure to eliminate the underlying truss substructure and underlying pivot shafts and bearings that rotate the &#39;263 reflector. 
   The primary objective of the instant collector system is cost reduction by using low cost corrugated board processed on existing machinery for high speed production of parabolic elements and using a cutting system to make parabolic shapes per U.S. Pat. Nos. 4,190,037 and 4,416,263 which states that flexible members on the top edge of support segments can be either U or L shaped, and cutouts between adjacent tabs can be eliminated if the bending modulus of the flexible piece so allows. FIGS. 2, 3, and 4 of U.S. Pat. No. 4,416,263 show typical flexible pieces. 
   Prior art U.S. Pat. No. 4,190,037 describes the use of expanded polyurethane, plastics, or corrugated paperboard as materials for support segments (Col 3 lines 35-38). 
   Using abundantly available and low cost corrugated board stock processed at high speed to form the parabolic shape of transverse segments in a unitary panel, a simplified collector support and pivot system in and vacuum insulators manufactured in large quantities like florescent lights, the instant disclosure offers potential for low cost collection of solar energy for supplementary electric power generation and, with commercially available devices for electrolysis to produce hydrogen from a renewable non-fossil fuel solar energy source for use in fuel cells. 
   In another embodiment, the heat absorbing fluid conduit allows concentrated solar rays to impinge on photovoltaic solar cells mounted on side planar surfaces. The parabolic curve is modified to project a dispersed band of solar rays on the extended surface of the solar cells. 
   With the above and other objectives in view, more information and understanding of the present invention may be achieved by reference to the following detailed description. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective top view of a solar concentrating collector illustrating a unitary reflector assembly with portions of the reflective surface removed, reflector pivot arms suspended from a conduit secured to a stationary support, a plurality of conduit insulators between pivotable bushings and arm support connections. Vertical plate extensions of the support includes a digital motor, helical/plate gear cable drive and attached members for a cable path with take-ups, pulleys, and connection to the reflector. 
       FIG. 2  is a plan top view schematic of a unitary reflector, cable drive systems between adjacent reflectors including cable drive components, pulleys and cable take-ups. The heat absorbing conduit along a focal line and means to secure it to the support are not shown (see  FIG. 11 ) Portions of the reflector surface are cutaway. 
       FIG. 3  is an end view schematic viewed from  3 - 3  of  FIG. 2  illustrating the reflector assembly position for concentrating rays at solar zenith (solid), early A.M, and late P.M. (dashed). The cable path for pivoting the reflector about the fixed conduit at solar zenith is shown solid. 
       FIG. 4  is a is a side elevation schematic viewed from  4 - 4  of  FIG. 2  illustrating the stationary support between adjacent collectors including vertical extension members to support the motor, helical/plate gear and capstan cable drive system. Vertical members include a plate and clamping means for securing the conduit to the stationary support. 
       FIG. 5  is a schematic end elevation viewed along  5 - 5  of  FIG. 4  illustrating the centrally mounted digital motor, helical/plate gear drive, pulleys and dual take-up cable drive for pivoting the reflector about the fixed conduit. The reflector is suspended by arms connected to a housing with bushings assembled on the conduit 
       FIG. 6  is a schematic end elevation viewed along  6 - 6  of  FIG. 4  illustrating a capstan, and cable drive pulleys mounted on one of two horizontal support arms, a conduit with pivoting housing connected to a reflector support arm, a unitary reflector and the central stationary support. 
       FIG. 7  is a schematic enlarged plan view similar to  FIG. 2  viewed from  7 - 7  of  FIG. 5  illustrating the cable drive motor/gears, capstan, cable pulleys and take-ups. 
       FIG. 8  is a schematic enlarged plan view from  8 - 8  of  FIG. 4  illustrating the conduit coupling with expansion space between adjacent conduit ends, means for clamping the coupling and conduit to the stationary support, and conduit pivot means outside of vertical supports for connection to reflector assembly arms. 
       FIG. 9  is an enlarged side cross section of the conduit clamp and coupling viewed along  9 - 9  of  FIG. 8  illustrating expansion space between adjacent conduit ends, resilient fluid seals and threaded means to apply a force against the deformable seals. Conduit and clamping means are secured to the stationary support. 
       FIG. 10  is an enlarged end view of the clamp and coupling shown in  FIG. 9 . 
       FIG. 11  is a side elevation of a collector conduit illustrating reflector support members at both ends with a plurality of intermediate conduit vacuum insulators with intermediate flexible members between insulators for expansion takeup. 
       FIG. 12  is an expanded side elevation of a conduit vacuum insulator illustrating a double glass sealed vacuum chamber, end seal means, and flexible resilient expansion take-ups. 
       FIG. 13  is an enlarged end elevation of the flexible expansion takeup. 
       FIG. 14  is a side elevation of a full length single glass embodiment of a vacuum chamber surrounding the heat absorbing conduit. 
       FIG. 15  is an enlarged side elevation of a conduit end seal for the single vacuum chamber of  FIG. 14 . 
       FIG. 16  is an end elevation of a modified parabolic curve reflector surface Illustrating solar rays directed to project a dispersed band of concentrated rays toward a loci of points for absorption on photovoltaic solar cells secured to inclined opposite sides of a triangular fluid conduit. The modified surface curve is shown solid. 
       FIG. 17  is an end elevation of a reflector surface modified (shown solid) to reflect and disperse solar rays from both sides toward a loci of focal points along the bottom surface of a square fluid conduit. 
       FIG. 18  is an end elevation of a reflector surface modified (shown solid) to reflect and disperse solar rays from each side toward a loci of focal points on opposite sides of a square fluid conduit. 
       FIG. 19  is a side elevation of a conduit coupling illustrating transition from triangular/square to round shapes at selected intervals of a collector array. The coupling includes an internal plug and inlet/outlet connections 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   In  FIG. 1 , the parabolic trough concentrating collector  1  reflects solar rays from reflector surface  2  (portions cutaway) supported by a plurality of parabolic shaped transversely aligned corrugated board segments  3  with flexible strips  27  superposed and attached to side surfaces (as shown in  FIGS. 1 ,  5 ,  6 ). 
   Reflected rays are directed to a focal line F co-incident with the centerline of conduit  4  which is secured to cross member  5  of vertically extended support  6  by clamp  7 . 
   In  FIG. 1 , support extensions  6 ,  6 ′ and cross supports  5 ,  14  are attached to stationary post  8  and are fixed. Housing  9  with inside bushings  10  include a downwardly extending portion  11  for connection to and support of reflector support arms  12 ,  12 ′ which are attached to both ends of unitary reflector  13 . The reflector  13 , support arms  12 ,  12 ′, housing extensions  11 ,  11 ′ and housings  9 ,  9 ′ pivot from conduit  4 . 
   In  FIG. 1 , the upper support extensions  6 ,  6 ′ include cross member  14  to support a programmable motor  15  and helical gear  16  engaging plate gear  17  through cross shaft  18  and turns cable drive capstan pulleys  19 ,  19 ′ extending from opposite sides of arms  20 ,  20 ′ to advance cable  24  for pivoting reflector  13  and cable  24 ′ for adjacent reflector  13 ′. Cable systems for each reflector  13  include air cylinders  23 ,  23 ′ located between arms  20 ,  20 ′ attached to vertically slidable take-up pulleys  22 ,  22 ′, and arranged for cable  24  slack take-up in transverse paths on both sides of the focal plane as the reflector is pivoted from morning to afternoon positions. 
   In  FIG. 1 , cylinders  23 ,  23 ′ control slack for cable path  24  for connection at  25 ,  25 ′ on opposite sides of reflector  13 . A similar cable system with capstan  19 ′ and cylinders  23 ,  23 ′ mounted on arm  20 ′ define a cable path  24 ′ (shown dashed) to pivot an adjacent reflector  13 ′ for attachment to opposite ends  25 ″,  25 ″ (shown near the bottom of  FIG. 1 ). 
   In  FIG. 1 , conduit  4  has a heat absorbing coating, and is surrounded by vacuum insulators  26  detailed in  FIGS. 11 ,  12 . 
   In  FIG. 2 , cable system  24  on support arms  20  on the left side is attached to reflector  13  at  25 ,  25 ′. A second cable system  24 ′ on arm  20 ′ (left side) is attached to reflector  13  at  25 ″,  25 ″. Each fixed support between collectors includes cable elements for connection to adjacent reflectors, for example,  13 , and  13 ′ on the left side and  13 ,  13 ″ on the right side. 
   In  FIG. 2 , arms  20 ,  20 ′ are attached to vertical, support members  6 .  6 ′cross supports  5  for supporting conduit clamp  7 , and support  14  for cable drive motor  15 , helical gear  16  and plate gear  17 , and cable pulleys  21  on arms  20 ,  20 ′are as described above and further detailed in  FIGS. 5 ,  6 . 
   In  FIG. 2 , unitary reflector assembly  13  includes parabolic shaped corrugated board supports  3  with flexible strips  27  on the curved surface for bonded attachment of a laminate with a reflective surface or a transparent material with an underlying reflective coating that faces the focal line. Parabolic supports  3  may be contained in slots between members  29  and bonded to  29  and corrugated board side panels  28 . 
   In  FIG. 3 , reflector assembly  13  is symmetrical about focal plane F. Support arms  12 ,  12 ′ are attached to the reflector and are suspended from portion  11  of housing  9  (shown in  FIG. 4 ) for pivoting about conduit  4 . 
   In  FIG. 3 , conduit  4  is secured to cross support  5  with clamp  7  and via columns  6 ,  6 ′ is fixed to stationary post  8 . 
   In the central position (shown solid) cable  24  is attached to reflector  13  as described above. 
   In  FIG. 3 , the cable system includes vertically movable pulleys  22 ,  22 ′ of  FIG. 1  and is shown solid with the reflector centered, and in the extended lower position  30 ,  30 ′ as the reflector pivots in either direction. Multiple cable wraps on the capstan prevent slippage, and slack occurs before and after the capstan when the reflector pivots. Downward movement of take-up pulleys  22 ,  22 ′ removes slack and maintains cable tension around capstan pulleys  19 ,  19 ′. Dashed arc  31  is the path of reflector bottom corners. 
   In  FIG. 4 , anchored post  8  has vertical extensions  6 ,  6 ′. Clamp  7  bolted to cross member  5  holds conduit  4  tight against cross support  5  in a non-rotating state. Housings  9 , with internal bushing  10  and extension portion  11  are connected to reflector arm  12  and allow reflector  13  to pivot as controlled by the programmed cable drive system. 
   In  FIG. 4 , upper cross member  14  supports the cable drive motor  15 , and helical gear  16  for engagement with plate gear  17  on shaft  18  which extends beyond vertical supports  6 ,  6 ′ for attachment of capstans  19 ,  19 ′ to drive cables  24 ,  24 ′ as described above. Enlarged views are shown in  FIGS. 5-7 . 
   In  FIGS. 5 and 6  all components are positioned and function as described herein. 
   In  FIG. 7 , plate  14  supports cable drive motor  15  and helical gear  16  for engagement with plate gear  17  on shaft  18  which rotates capstans  19 ,  19 ′ to drive cable  24 ,  24 ′ as described above. Cable pulleys  21 , take-up pulleys  22  and cylinders  23 ,  23 ′ are described above. 
   In  FIG. 8 , vertical supports  6 ,  6 ′ include intermediate plate support  5  to support conduit clamp  7 . Space S between adjacent conduit ends allows for conduit expansion. See  FIG. 9  for conduit expansion seals inside coupling  32  and conduit  4  are held stationary by clamp  7 . 
   In  FIG. 8 , housing  9  with inside bushing  10 , depending portion  11  for connection to reflector arms  12  and the attached unitary reflector  13  pivot about conduit  4  as described above. 
   Referring back to  FIG. 1 , a plurality of vacuum insulators  26  comprised of end connectors  26  and inner and outer glass tubes (see  FIG. 12 ) form a closed vacuum chamber  41 , are subject to expansion, and can slide on conduit  4 . 
   In  FIG. 8 , flexible springs  33  at each end of an insulator  26  deflect to absorb expansion without effect on conduit  4  or housing  9 . 
   In  FIG. 9 . clamp  7  secures coupling  32  and internal parts  35 ,  36 ,  37 , and conduits  4 ,  4 ′ spaced apart a distance S for conduit expansion clearance. Expansion of enclosing vacuum insulators  26  is isolated from expansion of conduit  4  (see  FIGS. 11 ,  12 ). Holes  38  arew for plug adjustment/removal. 
   In  FIG. 9 , conduits  4 ,  4 ′ slide within seal retainer  35 , and seal plug  36 . The inside circumference of  35  and outer circumference of seal plug  36  are threaded. Plug  36  is screwed inward to compress resilient conduit seal  37  to allow expansion movement parallel to focal axis F. 
   In  FIG. 10 , clamp  7  secures coupling  32  and internal parts to cross support  5 . Conduit saddle piece  7 ′ supports and positions conduit  4  for peripheral contact by clamp  7 . 
   In  FIG. 11 , conduit  4  is enclosed within a plurality of vacuum insulators slideable along the conduit and separated by flexible springs  33  to allow expansion of insulators  26  isolated from and without exerting force on conduit  4 . 
   In  FIG. 12 , double wall insulators  34  include end pieces  43 ,  43 ′, outer glass tube  39 , inner glass tube  40  hermetically sealed as at  42  with vacuum space  41  between  39  and  40 . Flexible springs  33  are adjacent insulator ends. 
   In  FIG. 13 , annular portion  44  of flexible spring  33  includes offset arms  45  and tabs  46  for contact with and force against end pieces  43 ,  43 ′ of the Insulator. 
   In the embodiment of  FIG. 14 , full length vacuum insulator  47  surrounds conduit  4  and extends between seal end caps  48 ,  48 ′. Details of seals for separate expansion of the single glass tube  51  and conduit  4  to maintain vacuum are described in  FIG. 15 . 
   In  FIG. 15 , seal end cap  48  and inside members fit over conduit  4 . Inner glass tube retainer  49  includes an annular relief for insertion of seal ring  50  and the end of glass tube  51 . Tube retainer  49  bears against seal ring  50 . Wedge shaped conduit seal  52  exerts axial force and seal pressure with axial force applied by an annular projection adjacent the conduit (see arrows) as the end cap is advanced inwardly by screw threads  53 . Outer flexible boot  54  provides a second vacuum seal between the glass tube and the conduit. Hose clamps  55  tighten outer flex boot vacuum seal  54  against end cap  48  and conduit  4 . 
   In  FIG. 16 , a reflector surface  2  is superposed over the curved upper edge of a reference parabolic shaped segment  3  (shown dashed) to focus solar rays along a focal line F coincident with the centerline of conduit  4 . 
   In  FIG. 16  for use with photovoltaic cells, the segment curve and shape of the reflector surface  2  is modified (shown solid) from a reference shape to reflect and disperse solar rays into a band of light directed to a loci of focal points impinging on photovoltaic cells P secured to both planar surfaces  62 ,  62 ′ on opposite sides of a triangular fluid conduit  63 . 
   One end of a transition section  57  fits over triangular conduit  63  and the other end fits over a round section of conduit  4  for insertion into coupling  32  (coupling shown in  FIG. 9 ). 
   In  FIG. 17 , a reference parabolic reflector  2 ′ is shown dashed. 
   In  FIG. 17  for use with photovoltaic cell, the parabolic curve and reflector shape  2 ′ is modified (shown solid) to reflect solar rays along a loci of focal points to project a band of light on the planar under surface  64  of a square conduit  55  and on photovoltaic cells P secured to the surface. 
   Transition coupling  57  fits over an end of conduit  55  and over a round piece of conduit  4  for insertion into coupling  32  (coupling shown in  FIG. 9 ). 
   In  FIG. 18 , a reference parabolic shape  2 ′ is shown dashed. A plurality of segments  3  and the reflector surface  2  are modified (shown solid) to disperse and reflect solar rays as a band of light impinging on photovoltaic cells P on both vertical sides  66 ,  66 ′ of conduit  65 . Transition coupling  57  fits over an end of conduit  65  and over a round piece of conduit for insertion into coupling  32  (coupling shown in  FIG. 9 ) 
   In  FIG. 19 , square or triangular shaped conduits provide planar support for photovoltaic cells P and include transition coupling  57  from triangular  58  to round  59  or square or round for insertion into coupling  32  of  FIG. 9 . 
   In  FIG. 19 , pre-selected transition couplings  57  have an internal plug  60  and inlet or outlet connections  61  to expel water over a pre-selected temperature to avoid solar cell damage. 
   All external surfaces of the unitary reflector assemblies of  FIGS. 1 ,  16 ,  17 , and  18  have an impervious coating for weatherproofing 
   The present invention may be embodied in other specific forms without departing from the spirit or special attributes, and it is therefore not restrictive, reference being made to the appended claims to indicate the scope of the invention. 
   REFERENCE NUMBERS 
   
       
         1  solar collector 
         2  reflector surface 
         3  parabolic transverse supports 
         4  heat absorbing conduit 
         5  cross member 
         6  upper support extension 
         7  conduit/coupling clamp 
         8  stationary post 
         9  housing 
         10  bushing 
         11  housing extension 
         12  reflector support arms 
         13  unitary reflector 
         14  cable drive support 
         15  programmable motor 
         16  helical gear 
         17  plate gear 
         18  drive cross shaft 
         19  cable drive capstan 
         20  horizontal arms 
         21  cable pulleys 
         22  take-up pulley upper position 
         23  air cylinder 
         24  cable 
         25  cable connector on reflector 
         26  conduit vacuum insulator 
         27  flexible strip with tabs 
         28  reflector side panels 
         29  para. support retainer 
       F solar ray focal line. 
         30  take-up pulley: lower position 
         31  arc of reflector path 
       S conduit expansion space 
         32  conduit coupling 
         33  flexible spring 
         34  double glass insulator 
         35  seal retainer 
         36  seal plug 
         37  conduit seal 
         38  outer glass tube 
         39  inner glass tube 
         40  vacuum space 
         42  hermetic seal 
         43  end piece 
         44  annular portion: spring 
         45  bent spring offset 
         46  contact tabs 
         47  full length insulator 
         48  conduit seal end cap 
         49  glass tube retainer 
         50  seal ring 
         51  glass tube 
         52  conduit wedge seal 
         53  adjusting threads 
         54  outer boot vacuum seal 
         55  sela hose clamps 
         56  vacuum space 
         57  transition piece 
         58  square/triangular section 
         59  round section 
         60  internal plug 
         61  fluid inlet/outlet 
         62  inclined side planes 
         63  triangular conduit 
         64  horizontal lower plane 
         65  square fluid conduit 
         66  sq. conduit side planes