CA1097169A - Refractor-reflector radiation concentrator - Google Patents
Refractor-reflector radiation concentratorInfo
- Publication number
- CA1097169A CA1097169A CA309,799A CA309799A CA1097169A CA 1097169 A CA1097169 A CA 1097169A CA 309799 A CA309799 A CA 309799A CA 1097169 A CA1097169 A CA 1097169A
- Authority
- CA
- Canada
- Prior art keywords
- reflector
- concentrator
- refractor
- major surface
- linear echelon
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Abstract
A small-area focus solar concentrator comprising a linear echelon refractor and a linear echelon reflector. The increments of the refractor are crossed at approximately 90.degree. to the increments of the reflector. The refractor and reflector cooperate to focus solar radiation incident on the front surface of the refractor to a small area focus in front of the refractor. The refractor-reflector structure permits relatively low cost, high power concentrators using refractorreflector matrices. Also, the refractor-reflector structure can be used to focus normal or non-normal incident radiation outside the path of the radiation to reduce or eliminate blockage of the radiation by an absorber located at the focus.
Description
~'7~169 The present invention relates to an optical concentrator for collecting and focusing incident radiation into a small area focus in front of the concentrator, and having an optical axis and front and rear portions intersected by the optical axis, wherein the front portion of the concentrator having a linear echelon refractor formed therein; the rear portion of the concentrator having a linear echelon reflector formed therein; and the con-centrator further comprising means for joining said refractor and said reflec-tor to form a refractor-reflector structure having the increments of sa:d linear echelon reflector crossed at approximately 90 relative to the incre-ments of said linear echelon refractor for directing radiation incident onthe front portion of the concentrator to the focus in front of the concen-trator.
A programmed matrix of individual concentrator panels can be used to form a large area refractor-reflector concentrator structure which focuses radiation to a high flux density. Also, normal and non-normal incident radiation can be focused outside the path of t:he inciclent radiation to reduce or eliminate blockage of the incident radiation by an absorber located at the focus.
The invention will now be described in greater detail with refer-ence to the accompanying drawings, in which:
Figure 1 is a perpsective representation of a crossed, linearechelon refractor-linear echelon reflector concentrator which embodies principles of the present invention, schematically showing the small area focusing of incident radiation.
Figure 2 is a vertical cross-sectional view, taken along the lines
A programmed matrix of individual concentrator panels can be used to form a large area refractor-reflector concentrator structure which focuses radiation to a high flux density. Also, normal and non-normal incident radiation can be focused outside the path of t:he inciclent radiation to reduce or eliminate blockage of the incident radiation by an absorber located at the focus.
The invention will now be described in greater detail with refer-ence to the accompanying drawings, in which:
Figure 1 is a perpsective representation of a crossed, linearechelon refractor-linear echelon reflector concentrator which embodies principles of the present invention, schematically showing the small area focusing of incident radiation.
Figure 2 is a vertical cross-sectional view, taken along the lines
2-2 of Figure 1, schematically tracing the vertical path of a meridional ray which passes through the concentrator.
. . - : .
..
.
; : ' :
~r397~9 Figure 3 is a horizontal cross-sectional view, taken along the lines 3-3 of Figure 1, schematically tracing the horizontal path o a meridional ray which -la-.. ... . . . .. .
"
: . . ~ ; . : . : : :
~9~9 passes through the concentrator.
Flgure 4 is a cross-sectional view of an alter-natlve embodiment of the present lnvention~ a concentrator panel element whlch is sealed about the edges.
Figure 5 is a cross-sectional view of another alternative embodiment o~ the present lnvention, a concen-trator panel element having an optically clear adhesive occupylng the space between the refractor and the reflector.
Figure 6 is a cross-sectional view of another alternative embodiment of the present invention, a concen-trator panel element having the reflector structure formed on an outer sur~ace.
Figure 7 is a cross-sectional view of stlll another alternative embodiment of the present invention, a concentrator panel ln whlch the refractor and the re-flector are ~ormed in outer sur~aces of a single, optically clear sheet.
Figure 8 is a cross-sectional view, taken at 90 to the vlew shown in Figure 7, of a single sheet con-centrator panel o~ the type shown in Figure 7 havingprotective members covering the refractor and reflector increments.
Figures 9A and 9B illustrate exemplary matrix arrangements for, respectively, the refractor and the re-flector of the present invention.
Figure 10 is a schematlc representation of off-set focusing o~ normal incident radiation by a concentrator embodylng the principles of the present invention.
Figure 11 schematically illustrates offset , :. :
.: .. :.
~97 focusing of non-normal incident radiation by a concentrator embodying the principles of the present invention.
Flgure 12 schematically illustrates comblnation focusing of normal and non-normal incident radiation by a concentrator center panel and two concentrator side panels.
Referring to Figure 1, there is shown an exemp-lary optical concentrator panel 10 that embodies the prin-` ciples of the present invention. The concentrator panel 10 comprises a refractor structure 11 ln the form of an optlcally clear sheet 15 having ma~or surfaces on opposite front and back sides thereof that are formed, respectivelyg into a smooth surface 12 and a linear echelon refractor 13.
The refractor 13 comprises a substantially parallel array of increments 14-14. The concentrator panel 10 ~urther compri~es a reflector structure comprising a sheet 17 havlng a substantially planar, linear echelon reflector 18 formed ln the front surface thereof and positioned in opposed spatial relationship to (or contacting) the linear echelon refractor 13. The reflector 18 comprises a sub-O
stantially parallel array of increments 19-19 which form reflectlve surfaces. Preferably, the reflector 18 is ~pecularly re~lective and can be made reflective in a number of ways well known to those skllled in the art, as by applylng metal deposition to previously ~ormed incre~
ments 19-19.
With the llnear increments 19 19 of reflector 18 crossed ~l.e.~ positioned at an angle of approximately 90) with the linear increments 14-14 of the refractor 13 as shown ln Figure 1, the configuration of the refractor ,, . . ,., ;~
~L~3~7~69 lncrements and the reflector increments can be deslgned to focus radiation incident upon the smooth front sur~ace 12 of the refractor structure 11 to a small area ~ocus, p 9 in front of the refractor structure. As used here, "in rront of" refers to the three-dimensional space on the lncident radiation side of a plane coinciding with the plane of the concentrator and includes, but ls not llmited to, the space directly in front o~ the concentrator.
The area o~ "p" and the percentage of incldent radlation focused or "collected" at "p" is determlned by ~actors such as the values of the re~ractor and the re-flector increment angles and the accuracy o~ manufacture of the linear lncrements 14-14 and 19-19. Typically, the concentrator provides satisfactor~ per~ormance 1~ the re-fractor 13 and reflector 18 are crossed at an angle wlthlnthe approximate range 90 ~ 5.
It should be noted that the linear echelon re-fractor 13 has the structure of, and could be called~ a linear echelon lens. Thls structure, a linear Fresnel lens, is the analog of a solld cylindrlcal lens and is capable o~ ~ocusing rad~ation to a line focus. As dls-cussed below, the re~ractor 13 and the reflector 18 are deslgned to operate as an entity in ~ocusing llght, rather than as separate elements havlng separate line ~oci which cooperate to provide a point or small area focus. The generic term "refractor" is applied to structure 13 throughout, to avoid the in~erence of separate elements, separately ~ocused.
The ~ocuslng act~on o~ the optical concentrator , , ~
.. , .. ~ . - ~
. - . , .
~L~3~173L69 panel 10 can be examined by simpli~ied, meridlonal ray traces through single linear increments 14 and 19 ~n the X-Z and X-Y planes, respectively. As shown in Figure 2, in the X-Z plane the incldent ray is re~racted at the air 5 inter~ace of the smooth front surface 12 and at the air lnter~ace of re~ractor increment 14; then is reflected by the reflector linear increment 19; and is refracted at the alr interfaces of the refractor increment 14 and the smooth ~ront sur~ace 12 in traversing back through the refractor structure 11 to the ~ocus p. As shown ln Figure 3, in the X-Y plane the ray is refracted at the air inter~aces of planar surface 12 and refractor increment 14, then re-~lected at the rerlector increment 19 for refractlon at the refractor increment 14 and planar surface 12 in tra-versing the refractor structure 11 to the ~ocus p.
These slmplifled, two-dimenslonal ray traces are lllustratlve of the worklng of the concentrator panel 10 and are also useful in designing the re~ractor increment an~les and the reflector increment angles. Re~erring to Figure 2, the refractor increment angle is angle a sub-tended between sur~ace 32 and sur~ace 12. Similarly, re-~erring to Flgure 3, the reflector increment angle ls ~
subtended between sur~ace 34 and surface 40. The light ray paths through the concentrator and, thus, the focusing o~ the light rays are preferably controlled or altered by varying the angles a and ~ o~ the lndividual refractor and reflector increments. Those skilled in the art will appreciate that it is rrequently desirable to optimize the initial values o~ angles ~ and ~ provided by a two-, ; ,;
.
, . . . .
~, , , ~ , .
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dlmensional ray trace using a skew or three-dimensional ray trace.
Referring again to Fi~ure 1, the inward facing deslgn of the refractor 13 and reflector 18 decreases degradation of the refractor and reflector by wind, rain, sun, etc., and, because the external surfaces are smooth, facilitates cleaning the panel. The panel can be sealed from the amblent. For example, the ad~acent, lnward-facing refractor structure 11 and reflector structure 16 can be ~oined at mating, non-incremental areas formed ln the back surface of the optically clear sheet 15 and ln the front surface of the reflector sheet 17. This is illustrated ln Figure 4, where the refractor and reflector structures are shown as having matlng borders 23 and 24 which can be ~oined by means such as adhesive (not shown).
Also, a support panel 21 (indicated by the dotted outline in Flgure 4) can be affixed to the back of the reflector structure 16 so that the reflector structure and the re-~ractor structure 11 can be thin elements and need not be sel~-supporting.
Alternatively, as shown in Figure 5, an optlc-ally clear polymeric adheRlve 22 whlch has a lower index of refraction th~n the clear sheet 15 of positlve refrac-tor 13 (or a hlgher index of refractlon than sheet 15 when the re~ractor i~ negatlve) can be used to fill the space between the inward raclng refractor lncrements 14-14 and re~lector lncrements 19-19 and to attach the refractor to the reflectorO For example, if the optically clear sheet 15 is cellulose aceta~e butyrate (CAB), a sultable .. -.
. .,.~ ., ~ ., .
~7169 materlal 22 ls polyperrluorooctylsulronamldoethyl acrylate.
Thls approach eliminates the borders 23 and 24 (Flgure 4) and eliminates air interfaces at the refractor and the re-flector.
In still another alternative con~iguration, as shown ln Figure 6, the reflector increments 19-19 are on the outslde surface of the concentrator panel. In this embodlment~ sheet 17 ls clear to permit radiation to tra-verse the sheet. A support panel 28 (indlcated by dotted outllne) can be af~ixed to the back of the re~lector struc-ture 16.
Figure 7 shows another alternative conriguration, one in which the refractor structure 11 and the reflector structure 16 are formed in a single clear sheet 42. That is, the refractor lncrements 14-14 and the re~lector in-crements 19 19 are ~ormed in opposite sides o~ the sheet 42. This simple con~iguration e:liminates air interraces between the re~ractor and re~lector structures.
Referring to Figure 8, the sheet 42 can be en-~0 capsulated by a protective structure. The illustratedprotective structure comprises panels 43 and/or 44 whlch have flat outer surfaces to facilitate cleaning. The panels can be a~ixed to the re~ractor or reflector in several ways. As shown by way of example in Figure 8, the flat interlor surrace Or the clear protective panel 43 ls a~fixed to the refractor by an optlcally clear poly-meric adhesive 45, while the ~lat interior surface o~ panel 44 is attached to the re~lector by an adhesive 46, which need not be optically clear.
.
, .. . ~ .
' ' The above-described concentrator panel design is adaptable to the manu~acture of large area concentrator structures using programmed matrices of lndividual re~rac-tor and re~lector elements. The individual elements are 5 derived from the refractor structure 11 and the reflector structure 16 of concentration panel 10 (Figure 1). These matrix structures are use~ul for high power applications, such as thermal engines.
As shown in Figures 9A and 9B, typical cooperat-10 ing re~ractor matrix 31 and reflector matrix 36 utillze rows and columns, respectively, o~ refractor and reflector elements. The re~ractor matrix 31 o~ Figure 9A utilizes rows of indlvidual refractor elements 1-6 whlch are paral-le~ to the horlzontal axis of symmetry 37. The re~lector 15 matrix 36 of Figure 9B utlllzes columns of linear re~lector elements A-F which are parallel to the vertical axis o~
symmetry 38.
Corresponding rows and columns on opposite sldes Or the axes 37 and 38 are reversed relative to one another.
20 That ls, the axes 37 and 38 divide their respective ma-trices 31 and 36 into mirror lmage halves. When the re-~ractor matrix 31 and the re~lector matrix 36 are brought together with the axes 37 and 38 crossed 3 the re~ractor- t reflector matrices cooperate to provide small area ~ocus-25 ing of lncldent solar radlation in the same manner as the slngle element concentrator panel 10 o~ Figure 1. It wlll be appreciated that these arrangements are illustrative only, ~or other arrangements will be readily devised by those ~killed in the art.
.
- ~
: ~
. . . .
~9716~
g A 28 cm. x 28 cm. (11 in. x 11 in.) concentrator panel 10 was built to the design o~ Figure 1. The sheets 15 and 17 were polymethyl methacrylate (PMMA; n - 1.49) and had 50 linear increments per inch measured along a line perpendicular to the length o~ the increments. The thickness, t, o~ the sheets was .152 cm. (o.o60 lnch).
Vapor dèposltion was used to coat the surfaces 34 (Figure
. . - : .
..
.
; : ' :
~r397~9 Figure 3 is a horizontal cross-sectional view, taken along the lines 3-3 of Figure 1, schematically tracing the horizontal path o a meridional ray which -la-.. ... . . . .. .
"
: . . ~ ; . : . : : :
~9~9 passes through the concentrator.
Flgure 4 is a cross-sectional view of an alter-natlve embodiment of the present lnvention~ a concentrator panel element whlch is sealed about the edges.
Figure 5 is a cross-sectional view of another alternative embodiment o~ the present lnvention, a concen-trator panel element having an optically clear adhesive occupylng the space between the refractor and the reflector.
Figure 6 is a cross-sectional view of another alternative embodiment of the present invention, a concen-trator panel element having the reflector structure formed on an outer sur~ace.
Figure 7 is a cross-sectional view of stlll another alternative embodiment of the present invention, a concentrator panel ln whlch the refractor and the re-flector are ~ormed in outer sur~aces of a single, optically clear sheet.
Figure 8 is a cross-sectional view, taken at 90 to the vlew shown in Figure 7, of a single sheet con-centrator panel o~ the type shown in Figure 7 havingprotective members covering the refractor and reflector increments.
Figures 9A and 9B illustrate exemplary matrix arrangements for, respectively, the refractor and the re-flector of the present invention.
Figure 10 is a schematlc representation of off-set focusing o~ normal incident radiation by a concentrator embodylng the principles of the present invention.
Figure 11 schematically illustrates offset , :. :
.: .. :.
~97 focusing of non-normal incident radiation by a concentrator embodying the principles of the present invention.
Flgure 12 schematically illustrates comblnation focusing of normal and non-normal incident radiation by a concentrator center panel and two concentrator side panels.
Referring to Figure 1, there is shown an exemp-lary optical concentrator panel 10 that embodies the prin-` ciples of the present invention. The concentrator panel 10 comprises a refractor structure 11 ln the form of an optlcally clear sheet 15 having ma~or surfaces on opposite front and back sides thereof that are formed, respectivelyg into a smooth surface 12 and a linear echelon refractor 13.
The refractor 13 comprises a substantially parallel array of increments 14-14. The concentrator panel 10 ~urther compri~es a reflector structure comprising a sheet 17 havlng a substantially planar, linear echelon reflector 18 formed ln the front surface thereof and positioned in opposed spatial relationship to (or contacting) the linear echelon refractor 13. The reflector 18 comprises a sub-O
stantially parallel array of increments 19-19 which form reflectlve surfaces. Preferably, the reflector 18 is ~pecularly re~lective and can be made reflective in a number of ways well known to those skllled in the art, as by applylng metal deposition to previously ~ormed incre~
ments 19-19.
With the llnear increments 19 19 of reflector 18 crossed ~l.e.~ positioned at an angle of approximately 90) with the linear increments 14-14 of the refractor 13 as shown ln Figure 1, the configuration of the refractor ,, . . ,., ;~
~L~3~7~69 lncrements and the reflector increments can be deslgned to focus radiation incident upon the smooth front sur~ace 12 of the refractor structure 11 to a small area ~ocus, p 9 in front of the refractor structure. As used here, "in rront of" refers to the three-dimensional space on the lncident radiation side of a plane coinciding with the plane of the concentrator and includes, but ls not llmited to, the space directly in front o~ the concentrator.
The area o~ "p" and the percentage of incldent radlation focused or "collected" at "p" is determlned by ~actors such as the values of the re~ractor and the re-flector increment angles and the accuracy o~ manufacture of the linear lncrements 14-14 and 19-19. Typically, the concentrator provides satisfactor~ per~ormance 1~ the re-fractor 13 and reflector 18 are crossed at an angle wlthlnthe approximate range 90 ~ 5.
It should be noted that the linear echelon re-fractor 13 has the structure of, and could be called~ a linear echelon lens. Thls structure, a linear Fresnel lens, is the analog of a solld cylindrlcal lens and is capable o~ ~ocusing rad~ation to a line focus. As dls-cussed below, the re~ractor 13 and the reflector 18 are deslgned to operate as an entity in ~ocusing llght, rather than as separate elements havlng separate line ~oci which cooperate to provide a point or small area focus. The generic term "refractor" is applied to structure 13 throughout, to avoid the in~erence of separate elements, separately ~ocused.
The ~ocuslng act~on o~ the optical concentrator , , ~
.. , .. ~ . - ~
. - . , .
~L~3~173L69 panel 10 can be examined by simpli~ied, meridlonal ray traces through single linear increments 14 and 19 ~n the X-Z and X-Y planes, respectively. As shown in Figure 2, in the X-Z plane the incldent ray is re~racted at the air 5 inter~ace of the smooth front surface 12 and at the air lnter~ace of re~ractor increment 14; then is reflected by the reflector linear increment 19; and is refracted at the alr interfaces of the refractor increment 14 and the smooth ~ront sur~ace 12 in traversing back through the refractor structure 11 to the ~ocus p. As shown ln Figure 3, in the X-Y plane the ray is refracted at the air inter~aces of planar surface 12 and refractor increment 14, then re-~lected at the rerlector increment 19 for refractlon at the refractor increment 14 and planar surface 12 in tra-versing the refractor structure 11 to the ~ocus p.
These slmplifled, two-dimenslonal ray traces are lllustratlve of the worklng of the concentrator panel 10 and are also useful in designing the re~ractor increment an~les and the reflector increment angles. Re~erring to Figure 2, the refractor increment angle is angle a sub-tended between sur~ace 32 and sur~ace 12. Similarly, re-~erring to Flgure 3, the reflector increment angle ls ~
subtended between sur~ace 34 and surface 40. The light ray paths through the concentrator and, thus, the focusing o~ the light rays are preferably controlled or altered by varying the angles a and ~ o~ the lndividual refractor and reflector increments. Those skilled in the art will appreciate that it is rrequently desirable to optimize the initial values o~ angles ~ and ~ provided by a two-, ; ,;
.
, . . . .
~, , , ~ , .
~, - ' .,: - ~ ~ .
dlmensional ray trace using a skew or three-dimensional ray trace.
Referring again to Fi~ure 1, the inward facing deslgn of the refractor 13 and reflector 18 decreases degradation of the refractor and reflector by wind, rain, sun, etc., and, because the external surfaces are smooth, facilitates cleaning the panel. The panel can be sealed from the amblent. For example, the ad~acent, lnward-facing refractor structure 11 and reflector structure 16 can be ~oined at mating, non-incremental areas formed ln the back surface of the optically clear sheet 15 and ln the front surface of the reflector sheet 17. This is illustrated ln Figure 4, where the refractor and reflector structures are shown as having matlng borders 23 and 24 which can be ~oined by means such as adhesive (not shown).
Also, a support panel 21 (indicated by the dotted outline in Flgure 4) can be affixed to the back of the reflector structure 16 so that the reflector structure and the re-~ractor structure 11 can be thin elements and need not be sel~-supporting.
Alternatively, as shown in Figure 5, an optlc-ally clear polymeric adheRlve 22 whlch has a lower index of refraction th~n the clear sheet 15 of positlve refrac-tor 13 (or a hlgher index of refractlon than sheet 15 when the re~ractor i~ negatlve) can be used to fill the space between the inward raclng refractor lncrements 14-14 and re~lector lncrements 19-19 and to attach the refractor to the reflectorO For example, if the optically clear sheet 15 is cellulose aceta~e butyrate (CAB), a sultable .. -.
. .,.~ ., ~ ., .
~7169 materlal 22 ls polyperrluorooctylsulronamldoethyl acrylate.
Thls approach eliminates the borders 23 and 24 (Flgure 4) and eliminates air interfaces at the refractor and the re-flector.
In still another alternative con~iguration, as shown ln Figure 6, the reflector increments 19-19 are on the outslde surface of the concentrator panel. In this embodlment~ sheet 17 ls clear to permit radiation to tra-verse the sheet. A support panel 28 (indlcated by dotted outllne) can be af~ixed to the back of the re~lector struc-ture 16.
Figure 7 shows another alternative conriguration, one in which the refractor structure 11 and the reflector structure 16 are formed in a single clear sheet 42. That is, the refractor lncrements 14-14 and the re~lector in-crements 19 19 are ~ormed in opposite sides o~ the sheet 42. This simple con~iguration e:liminates air interraces between the re~ractor and re~lector structures.
Referring to Figure 8, the sheet 42 can be en-~0 capsulated by a protective structure. The illustratedprotective structure comprises panels 43 and/or 44 whlch have flat outer surfaces to facilitate cleaning. The panels can be a~ixed to the re~ractor or reflector in several ways. As shown by way of example in Figure 8, the flat interlor surrace Or the clear protective panel 43 ls a~fixed to the refractor by an optlcally clear poly-meric adhesive 45, while the ~lat interior surface o~ panel 44 is attached to the re~lector by an adhesive 46, which need not be optically clear.
.
, .. . ~ .
' ' The above-described concentrator panel design is adaptable to the manu~acture of large area concentrator structures using programmed matrices of lndividual re~rac-tor and re~lector elements. The individual elements are 5 derived from the refractor structure 11 and the reflector structure 16 of concentration panel 10 (Figure 1). These matrix structures are use~ul for high power applications, such as thermal engines.
As shown in Figures 9A and 9B, typical cooperat-10 ing re~ractor matrix 31 and reflector matrix 36 utillze rows and columns, respectively, o~ refractor and reflector elements. The re~ractor matrix 31 o~ Figure 9A utilizes rows of indlvidual refractor elements 1-6 whlch are paral-le~ to the horlzontal axis of symmetry 37. The re~lector 15 matrix 36 of Figure 9B utlllzes columns of linear re~lector elements A-F which are parallel to the vertical axis o~
symmetry 38.
Corresponding rows and columns on opposite sldes Or the axes 37 and 38 are reversed relative to one another.
20 That ls, the axes 37 and 38 divide their respective ma-trices 31 and 36 into mirror lmage halves. When the re-~ractor matrix 31 and the re~lector matrix 36 are brought together with the axes 37 and 38 crossed 3 the re~ractor- t reflector matrices cooperate to provide small area ~ocus-25 ing of lncldent solar radlation in the same manner as the slngle element concentrator panel 10 o~ Figure 1. It wlll be appreciated that these arrangements are illustrative only, ~or other arrangements will be readily devised by those ~killed in the art.
.
- ~
: ~
. . . .
~9716~
g A 28 cm. x 28 cm. (11 in. x 11 in.) concentrator panel 10 was built to the design o~ Figure 1. The sheets 15 and 17 were polymethyl methacrylate (PMMA; n - 1.49) and had 50 linear increments per inch measured along a line perpendicular to the length o~ the increments. The thickness, t, o~ the sheets was .152 cm. (o.o60 lnch).
Vapor dèposltion was used to coat the surfaces 34 (Figure
3~ with a specularly re~lective, aluminum coating. The angles a and ~ were designed via ray trace analysis to provide a collection ef~iciency o~ 0.95. That is, angles ~ and ~ were used that established a diameter o~ the small area ~ocus, or "containment circle" p, ~or which 95% o~ the transmitted ray~ pass through the ~ocus. This diameter is about 1.90 cm. (.75 inch) for the 28 cm. x 28 cm. (11 in.
x 11 in.) concentrator panel.
A large area, e.g., 335 cm. x 335 cm. (11 ~t. x 11 ft.), concentrator can be readlly assembled using a ;;~
plurality of 28 cm. x 28 cm. (11 ln. x 11 in.) concentrator panels in the matrix design o~ Figures 9A and 9B. Based upon the 1.9 cm. (.75 inch) diameter containment circle or rOcus for the 28 cm. x 28 cm. (11 in. x 11 in.) panel 10, a ~ocus radius of about 10 cm. (4.0 lnches) would provide a collection e~iciency o~ 0.95 ror the 335 cm. x 335 cm.
(11 ft. x 11 ~t~) panel matrix. The power in watts within the rocus can be estimated by:
W = H x AC x TR x CE, where H - solar flux den~ity, assume approximately 100 watts per square foot incldent on panel;
-: . , .: .
" .
, ~:.' ' : . . ~
~ g~j9 AC = concentrator panel area;
TR = transmission and re~lection efficiency, 0.96 transmission per inter~ace and o.88 per reflection provides TR = (.96)4 (.88) = 0.75;
CE - collection efficiency, designed to be 0.95.
For a 335 cm. x 335 cm. (11 ~t. x 11 ft.) panel that concentrates 95~ o~ the transmitted solar radiation with a 10 cm. (4 inch) radius contalnment circle at 335 cm. (11 ft.), the power is then approximately:
W - 100 x 121 x 0.75 x 0.95 = 8.5 kilowatt.
The matrix con~iguratlon o~ the present invention is not limlted to that shown in Flgures 9A and 9B. For example, the number of panels in ~the rows (columns) could be reduced by using extruded lense~ Or greater width (height).
The crossed linear solar panel descrlbed above may be designed to focus normal solar radiation (lncoming rays which are incident at an angle of 90 to the panel) to a point on an optlcal axis 47 (Figure 1) whlch is directed perpendicular to ths panel and passes through the center of the panel. In this case9 the focus is with-in the path o~ the perpendicular or normal incident raysand the design is termed "normal" ~ocus. However, other deslgn con~iguratlons are possible which diminish or avold the resultant blockln~ of incoming radiation by the flux absorber (not shown). For example, as shown schematically ., , : . ~ ,: . ~, . .
.. ... . . ..
....
~.~39716~
in Figure lO, solar concentrator panel or panel matrlx 25 (using refractor-re~lectbr matrices derived from matrices 31 (Figure 9A~ and 36 (Figure 9B) or an individual concen-trator based upon panel 10) directs normal radiation to a focus "p" which is outside o~ or offset ~rom the incldent rays and thus out of the path of the incident radiation.
This reduces or eliminates blockage. The deslgn is termed ~ -"normal of~-set" focus.
Alternatively, as shown in Figure ll, a solar panel or panel matrix 26 can be programmed for ~ocuslng non-normal radiation to a focus which is of~set to elimi-nate receiver blockage of the non-normal radiation. This design is "non-normal o~rset." 0~ course, "non-normal" ;~-~
focus design, i.e., focus within the path of the incident, non-normal radiation is also posslble.
Combinations of normal, normal offset, non-normal and non-normal offset focus designs are possible. As shown by way of example in Figure 12, combination concentrator 27 uses normal center panel lO and non-normal offset slde panels 2~-26.
It should be noted that, unlike the matrices 31 and 36 shown in Figures 9A and 9B, the non-normal and off-set matrix designs usually will not have mirror-image halves.
This is because, and as ls evident ~rom Figures lO and 11 3 the light-directing requirements for the non-normal and of~set deslgns are non-symmetrical.
It wlll be appreciated by those skllled in the art th~t incorporation o~ designs such as of~set or non-normal ~ocus designs ln one piece, prior art concentrators , ~f3~ ~ ~ 6 may require complex shapes and difficult and expensive forming processes. In addition, because of radial symmetry, the circular Fresnel reflector cannot direct non-normal radiation to an offset focus as per Figure 11. However, of~set, non-normal and other design conflgurations can be readily achieved using either an individual concentrator panel or a panel matrix incorporatlng the principles of the present invention.
.: ' :, ~ - :. , : :
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x 11 in.) concentrator panel.
A large area, e.g., 335 cm. x 335 cm. (11 ~t. x 11 ft.), concentrator can be readlly assembled using a ;;~
plurality of 28 cm. x 28 cm. (11 ln. x 11 in.) concentrator panels in the matrix design o~ Figures 9A and 9B. Based upon the 1.9 cm. (.75 inch) diameter containment circle or rOcus for the 28 cm. x 28 cm. (11 in. x 11 in.) panel 10, a ~ocus radius of about 10 cm. (4.0 lnches) would provide a collection e~iciency o~ 0.95 ror the 335 cm. x 335 cm.
(11 ft. x 11 ~t~) panel matrix. The power in watts within the rocus can be estimated by:
W = H x AC x TR x CE, where H - solar flux den~ity, assume approximately 100 watts per square foot incldent on panel;
-: . , .: .
" .
, ~:.' ' : . . ~
~ g~j9 AC = concentrator panel area;
TR = transmission and re~lection efficiency, 0.96 transmission per inter~ace and o.88 per reflection provides TR = (.96)4 (.88) = 0.75;
CE - collection efficiency, designed to be 0.95.
For a 335 cm. x 335 cm. (11 ~t. x 11 ft.) panel that concentrates 95~ o~ the transmitted solar radiation with a 10 cm. (4 inch) radius contalnment circle at 335 cm. (11 ft.), the power is then approximately:
W - 100 x 121 x 0.75 x 0.95 = 8.5 kilowatt.
The matrix con~iguratlon o~ the present invention is not limlted to that shown in Flgures 9A and 9B. For example, the number of panels in ~the rows (columns) could be reduced by using extruded lense~ Or greater width (height).
The crossed linear solar panel descrlbed above may be designed to focus normal solar radiation (lncoming rays which are incident at an angle of 90 to the panel) to a point on an optlcal axis 47 (Figure 1) whlch is directed perpendicular to ths panel and passes through the center of the panel. In this case9 the focus is with-in the path o~ the perpendicular or normal incident raysand the design is termed "normal" ~ocus. However, other deslgn con~iguratlons are possible which diminish or avold the resultant blockln~ of incoming radiation by the flux absorber (not shown). For example, as shown schematically ., , : . ~ ,: . ~, . .
.. ... . . ..
....
~.~39716~
in Figure lO, solar concentrator panel or panel matrlx 25 (using refractor-re~lectbr matrices derived from matrices 31 (Figure 9A~ and 36 (Figure 9B) or an individual concen-trator based upon panel 10) directs normal radiation to a focus "p" which is outside o~ or offset ~rom the incldent rays and thus out of the path of the incident radiation.
This reduces or eliminates blockage. The deslgn is termed ~ -"normal of~-set" focus.
Alternatively, as shown in Figure ll, a solar panel or panel matrix 26 can be programmed for ~ocuslng non-normal radiation to a focus which is of~set to elimi-nate receiver blockage of the non-normal radiation. This design is "non-normal o~rset." 0~ course, "non-normal" ;~-~
focus design, i.e., focus within the path of the incident, non-normal radiation is also posslble.
Combinations of normal, normal offset, non-normal and non-normal offset focus designs are possible. As shown by way of example in Figure 12, combination concentrator 27 uses normal center panel lO and non-normal offset slde panels 2~-26.
It should be noted that, unlike the matrices 31 and 36 shown in Figures 9A and 9B, the non-normal and off-set matrix designs usually will not have mirror-image halves.
This is because, and as ls evident ~rom Figures lO and 11 3 the light-directing requirements for the non-normal and of~set deslgns are non-symmetrical.
It wlll be appreciated by those skllled in the art th~t incorporation o~ designs such as of~set or non-normal ~ocus designs ln one piece, prior art concentrators , ~f3~ ~ ~ 6 may require complex shapes and difficult and expensive forming processes. In addition, because of radial symmetry, the circular Fresnel reflector cannot direct non-normal radiation to an offset focus as per Figure 11. However, of~set, non-normal and other design conflgurations can be readily achieved using either an individual concentrator panel or a panel matrix incorporatlng the principles of the present invention.
.: ' :, ~ - :. , : :
: ,. . .: . ~:
Claims (10)
The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
1. An optical concentrator for collecting and focusing incident radiation into a small area focus in front of the concentrator, and having an optical axis and front and rear portions intersected by the optical axis, wherein the front portion of the concen-trator having a linear echelon refractor formed therein;
the rear portion of the concentrator having a linear echelon reflector formed therein; and the concentrator further comprising means for joining said refractor and said reflector to form a refractor-reflector structure having the increments of said linear echelon reflector crossed at approximately 90° relative to the increments of said linear echelon refractor for directing radiation incident on the front portion of the concentrator to the focus in front of the concentrator.
the rear portion of the concentrator having a linear echelon reflector formed therein; and the concentrator further comprising means for joining said refractor and said reflector to form a refractor-reflector structure having the increments of said linear echelon reflector crossed at approximately 90° relative to the increments of said linear echelon refractor for directing radiation incident on the front portion of the concentrator to the focus in front of the concentrator.
2. The concentrator of claim 1, wherein said concentrator further comprises at least a second crossed refractor-reflector structure adapted to direct radiation incident on the front portion thereof to the focus in front of the concentrator.
3. The optical concentrator of claim 2, wherein said front portion comprises a planar sheet of optically clear material having first and second major surfaces on opposite sides thereof, said first major surface being substantially smooth and said second major surface having a linear echelon refractor formed therein; and said rear portion comprising a reflector structure having at least a first substantially planar major surface and a linear echelon reflector formed in said first major surface of the reflector structure.
4. The concentrator of claim 3, wherein said joining means comprises mating, non-incremental portions formed in said second major surface of the planar sheet and in said first major surface of the reflector structure.
5. The concentrator of claim 3, wherein said joining means comprises optically clear material between said linear echelon refractor and said linear echelon reflector which affixes said planar sheet to said reflector structure.
6. The concentrator of claim 3, wherein said reflector structure is an optically clear sheet having a second substantially planar major surface on the opposite side of said structure from said first major surface, said second major surface of the reflector structure being closer to said planar sheet than said first major surface of the reflector structure.
7. The optical concentrator of claim 2, wherein said joining means comprises an optically clear sheet having front and rear major surfaces, said linear echelon refractor and said linear echelon reflector being formed, respectively, in said front major surface and said rear major surface.
8. The optical concentrator of claim 7 wherein at least one of said linear echelon refractor and said linear echelon reflector having a protective covering thereover.
9. The concentrator of claim 3, 4, or 5 wherein said major surfaces are approximately 11 in. by 11 in. and wherein said refractor increments and said reflector incre-ments number approximately fifty per inch measured along a line extending perpendicular to the length of the incre-ments, and said planar sheet being approximately 0.060 inches thick for providing a collection efficiency of 0.95 within a focus of approximately 0.75 inch diameter.
10. A concentrator for focusing radiation to a small area of high flux intensity, wherein said concentra-tor comprises at least two concentrator panels, each panel comprising:
a planar sheet of optically clear material having first and second major surfaces formed, respectively, in front and back sides thereof, the first major surface being substantially smooth and the second major surface having a linear echelon lens formed therein;
a planar, linear echelon reflector corresponding to the planar sheet of optically clear material, the incre-ments of the linear echelon reflector being crossed at approximately 90° to the increments of the linear echelon lens; and the linear echelon lens cooperating with the corresponding linear echelon reflector to direct radiation incident on the first, smooth major surface of the planar sheet to a focus in front thereof.
a planar sheet of optically clear material having first and second major surfaces formed, respectively, in front and back sides thereof, the first major surface being substantially smooth and the second major surface having a linear echelon lens formed therein;
a planar, linear echelon reflector corresponding to the planar sheet of optically clear material, the incre-ments of the linear echelon reflector being crossed at approximately 90° to the increments of the linear echelon lens; and the linear echelon lens cooperating with the corresponding linear echelon reflector to direct radiation incident on the first, smooth major surface of the planar sheet to a focus in front thereof.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA309,799A CA1097169A (en) | 1978-08-22 | 1978-08-22 | Refractor-reflector radiation concentrator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA309,799A CA1097169A (en) | 1978-08-22 | 1978-08-22 | Refractor-reflector radiation concentrator |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1097169A true CA1097169A (en) | 1981-03-10 |
Family
ID=4112182
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA309,799A Expired CA1097169A (en) | 1978-08-22 | 1978-08-22 | Refractor-reflector radiation concentrator |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1097169A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4505264A (en) * | 1983-12-27 | 1985-03-19 | Universite Laval | Electromagnetic wave concentrator |
-
1978
- 1978-08-22 CA CA309,799A patent/CA1097169A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4505264A (en) * | 1983-12-27 | 1985-03-19 | Universite Laval | Electromagnetic wave concentrator |
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