CA1087946A - Solar energy collection system - Google Patents
Solar energy collection systemInfo
- Publication number
- CA1087946A CA1087946A CA315,800A CA315800A CA1087946A CA 1087946 A CA1087946 A CA 1087946A CA 315800 A CA315800 A CA 315800A CA 1087946 A CA1087946 A CA 1087946A
- Authority
- CA
- Canada
- Prior art keywords
- collector
- tube
- envelope
- transparent surface
- rays
- 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
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
- F24S10/00—Solar heat collectors using working fluids
- F24S10/40—Solar heat collectors using working fluids in absorbing elements surrounded by transparent enclosures, e.g. evacuated solar collectors
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
- F24S23/00—Arrangements for concentrating solar-rays for solar heat collectors
- F24S23/70—Arrangements for concentrating solar-rays for solar heat collectors with reflectors
- F24S23/80—Arrangements for concentrating solar-rays for solar heat collectors with reflectors having discontinuous faces
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/40—Solar thermal energy, e.g. solar towers
- Y02E10/44—Heat exchange systems
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Life Sciences & Earth Sciences (AREA)
- Sustainable Development (AREA)
- Sustainable Energy (AREA)
- Thermal Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Photovoltaic Devices (AREA)
Abstract
IMPROVED SOLAR ENERGY COLLECTION SYSTEM
ABSTRACT OF THE DISCLOSURE
A solar energy collector comprises an elongate evacuated envelope through which passes a two-way flow pipe. A nearly ideal reflector surface having an efficiency greater than 75% is provided in the envelope to reflect and focus incident light on the fluid flow pipe.
ABSTRACT OF THE DISCLOSURE
A solar energy collector comprises an elongate evacuated envelope through which passes a two-way flow pipe. A nearly ideal reflector surface having an efficiency greater than 75% is provided in the envelope to reflect and focus incident light on the fluid flow pipe.
Description
10~734~i The pres~nt invcntion relates to a solar energy r,' collection system. This application is a division of copending Canadian application Serial No. 293,819 filed December 23, 1977.
In our prior Canadian patent application Serial No. 275,382, (now Canadian Patent No. 1,027,820) there is described a solar energy collector compriSing an outer evacuated envelope having an upper transparent surface to admit light rays to the envelope and a two-way tube extending in the envelope from one end thereof towards - the other and having a selectively absorbing surface for ; selectively absorbing energy having predetermined wave-lengths and rejecting other wavelengths.
An elontage reflector surface is located ,~ internally of the envelope and is arranged to reflect light received through the upper transparent surface onto the two-way tube. The locus of the reflector surface is designed to achieve maximum efficiency and is the shape -,' required to ensure that all incident rays reoeived into ;; 20 the envelope through the upper transparent surface)within the acceptance angle determined by the equation:
~' ~ . C = 1 ;' sin~
:''.', . "
where C is the concentration ratio (i.e., the ratio of the transverse width of the upper transparent surface to the outer circumference of the tube) and ~ is the -~';' acceptance angle, are concentrated on the two-way tube ~`' while rays outside the acceptance angle are reflected.
, .. .
The shape of the reflector surface determined by the above equation represents the maximum efficiency . , , of the collector. In accordance with the present . . ~
' :
''' ' , ' ~ ' . ., , ,. ~
~ 7946 .. invention, the locus o~ the rePlector surface i.s the shape required to ensure that from ahout 75% of, preferably . from about 90% of, to less than the maximum efficiency of the collector is realized. Although there is a decrease in efficiency, advantages in truncation o the reflector . surface, with consequentially reduced material costs, result.
. . .
Accordingly, the present invention provides a . solar collector comprising: an outer evacuated elongate ;- 10 envelope having an upper transparent surface to admit ~- light rays to the envelope, a tube extending in the envelope from one end thereof towards the other for conveying fluid to be heated into the collector and for removing heated fluid from the collector, the tube comprising a concentrically-arranged pair of inner and _, , :~.- . outer tubes extending from one end of the envelope ~ substantially to the other and an end closure at the other ,;:;,;
. end constructed to define a flow channel from the inner to the outer tube or vice versa, whereby fluid to be ... ` 20 heated enters the collector from the same end as heated ................ fluid is removed from the collector, a selectively ~` absorbing surface on the tube for selectively absorbing ., ~ .
:.; . energy having predetermined wavelengths and rejecting .. . .
.. other wavelengths, and an elongate reflector surface . .~ .
located internally of the envelope and arranged to .
; reflect light received through the transparent surface onto the tube, the upper transparent surface and the tube ., ,.~
being dimensioned to provide a concentration ratio which is the ratio of the transverse width of the upper trans-~ . 30 parent surface to the outer circumference of the tube and `. has a value greater than about 0.5, the locus of the ~: - 3 -. .
.. , ~ .
~ .
. . .
- 10~17946 reElec~.or sur~ace b~iny ~he sh~p~ requ:ir~d to ~nsure that :
from about 75% oE to less than -the maximum eficiency of the coll~ctor is realized, the maximum efficiency being .
~; provided by the shape required to ensure that all incident .
rays received into the envelope through the upper trans-~ parent surface within the acceptance angle determined by ~ .
;. the equation~
C=
sin~
where C is the concentration ratio and ~ is the acceptance .
angle, are concentrated on the tube while rays outside the acceptance angle are reflected. - :
The invention is described further, by way o illustration, with reference to the accompanying drawings, . -.
wherein: .
, . ~ . , .:
; Figure 1 is a perspective view, with parts cut away, illustrating a solar coIlector constructed in accor- .
., dance with this invention; and .
Figure 2 is a section taken on line 2-2 of ~.
. 20 Figure 1. .-.. ~ In the drawings, a solar collector 10 is pro- ¦
~ vided in the form of an elongate, integral generally tub- ~ 1 r::; ular element, preferably fabricated wholly of glass or .-. other convenient material, having a tubular end portion ~ 12.
A tube 14 extends generally axially of the collector 10 and the portion of the tube 14 extending .~.
into the collector 10 beyond the tubular end portion 12 is surrounded by an axially extending parallel tubular .. 30 portion 16 integral with and of the same diameter as the ' :'.
... .
.,:
. .. : - ,, ~ , -~7946 :
tubular end portion 12 at one end and closed at the other !
beyon~ the ~xtremi ty oE th~ ~ube ~ o d~E:Lne a :Eluid .Elow path ~hrough the collector 10. rrhe ~luid flow pakh extends ~ internal~y ~ the tube 14 and then between the internal sur-;~ face of the tubular portion 16 and the outer surface o~ the tube 14, or vice versa, depending on the direction of fluid flow.
An outer envelope 18 surrounds and encloses the tube 14 and the tubular portion 16 and is integral with the tubular end portion 12. The space 20 between the ~uter envelope 18 and the tubular portion 16 is evacuated.
The outer envelope 18 is contoured as shown in the sectional view of Figure 2 and has a relatively flat top ~' surface portion 22 to allow entry of sun rays into the collector 10.
The remainder of the inner surface of the outer envelope 18 is coated with a highly reflective material 24, such as silver, to reflect sun rays entering the collector 10 through the top surface 22 and impinging on the envelope inner surface.
, :~
The tubular portion 16 has a high absorbance at all incident angles in the spectral wavelength of 0 to 3 x 10 6 meters. In order to decrease heat losses, the absorbance for higher wavelengths should be low. The selective absorbance , may be achieved by coating the outer surface of the tubular;~ ., ~` portion 16 with a suitable material, such as chrome black.
The circular cross section of tube 16 may be replaced by ..~1 ~ any other desired cross-sectional shape.
., .
In the collector 10, the concentration ratio (C) refers to the relative dimensions of the radiation-receiving portion and radiation-absorbing portion of the collector, ,.;.
.: , .~., ~ ., . ~,; .
~;
- .
. . .
. , , , . -.... . .
., ~- 10`~79"~
while the acceptance ang:Le (~) reEexs to ~he angle withln which all rays entering the collector 10 through the radia-tion-receiving portion are absorbed by the radiation- ¦
absorbing por~ion of the collector while rays entering the ~- collector through the radiation-receiving portion outside that angle are reflected.
Referring to Figure 2, the concentration ratio (C) ; of the collector is determined by the ratio: ¦
C = Entrance Aperture Width = A
Absorber Tu~e Circumference 2 ~ R
~ lO The acceptance angle (~) is the angle to the vertical ; axis within w~ich all rays entering the collector through the upper surface 22 are absorbed by the two~way tube 16 while .. , , rays outside that angle are reflected back without being absorbed. The limiting condition far acceptance of rays ',l for absorption is a ray which is reflected by the reflecting :,. .
surface to pass tangentlally to the two-way tube 16, as illustrated.
; In a collector of maximum efficiency, the ~'! acceptance angle (0) is determined by the concentration ratio (C~ in accordance with the equation:
. i ~C =
; sin and the locus of the reflecting surface 24 of the collector ;~.
is the shape corresponding to that equation.
It will be seen from the above equations that, as the concentration ratio (C) increases, the acceptance angle (~) decreases. The value of the acceptance angle will determine the length of time during a given day when .. . .
the collector will absorb light rays, assuming that the collector is located in a fixed relationship with respect to the sun mavement. The value of the concentration ratio will determine the temperature rise attainable in the .;, .
, i~ ~) :
'' ' ' . , .
.
7~34~
;
two-way tube during the time that rays are accepted :~ within the acceptance ~ngle, with an increase in concentra-tion ratio leading to an increase in temperature under otherwise flxed conditions.
; The minimum concentration ratio for the -` ` collector is about 0.5 and the upper limit of concentration .
ratio for a fixed location system is about 10. If the ~ collector is mounted to track the sun's movement on a . .
' daily basis or if the sun's rays can be concentrated :~
~ 10 within the narrow acceptance angle which exists at these :~
`i high concentration ratios, then the concentration ratio : may exceed 10, although it will rarely exceed 50.
,jj .
i:l Preferably, the concentration ratio is about `~~ 1.0 to about 3.0, most preferably about 1.5 to about 2.0, .
which provides a good balance of acceptance angle and :
' concentration ratio, so that the collector has a sufficiently wide acceptance angle to absorb rays over a .
1 long period of daylight hours, while at the same time ~
:: providing a good heating effect on the fluid flowing .
.. 1 . .
through the collector. .
If the physical height of the body portion 18 ~; is decreased without otherwise altering the shape of the , reflector surface 24, as shown in the modification of Figure 2 wherein the dotted outline represents the locus ,~; i ~` of maximum efficiency and the solid outline represents ~:
. ; .
; the decreased height body, the concentration ratio is decreased and thus leads to a less than maximum efficiency of collector 10.
. ~
: Since, however, the upper portions of the reflec- !
.. 30 ting surface 24 adjacent the upper surface 22 are almost , , parallel and have only a minor effect on the rays which ,.."~
.... .
:, . ;, .
. .
.: - .
g~6 :
are absorb~d by the tube 16, the loss in e~Elciency nee~
~ only be minor, while the material saving achle~ed thereby : ~` is considerabl~. ¦
In this invention, the maximum loss of e~ficiency rom ideal conditions is about 25~, while preferably the loss o~ ef~iciency tolerated on truncation is less than about .
10%. -The outer envelope 18 of the collector preferably is comprised of (1) an upper surface portion formed of ~, 10 glass and constituting the transparent surface and (2) a lower body portion constructed of vitreous ceramic :
. .~ . , 's` material formed from clay and various fluxes. Vitreous.
, ceramic materials are inexpensive and readily available, :
and can be ~ormed into shaped objects by molding or , axtrusion, making them ideal for formation of an integral molded or extruded lower body portion.
~ The collectors of this invention may achieve a ,I photovoltaic function by producing an electrical output from collected solar energy. The two-way tube 16 may be -coated with light energy actuable electricity generating material layers which communicate through suitable elec- ¦
' trical connection to exterior of each collector 10.
.,~
...
.
: ." .
'`', ~ -:
., : :
~:.,. ;
,. i , , ` ;'~ .
, . ~ .
, ~; ..
~ - 6B
, ' ' '?~'~lJ`
: ~ ~;i rj .~.
"
'.. ;, ' . , -' ' ' . ' ~ ~ .: .
'~'; ', '' ' ' ~ ' , :, . ~ . .. .
In our prior Canadian patent application Serial No. 275,382, (now Canadian Patent No. 1,027,820) there is described a solar energy collector compriSing an outer evacuated envelope having an upper transparent surface to admit light rays to the envelope and a two-way tube extending in the envelope from one end thereof towards - the other and having a selectively absorbing surface for ; selectively absorbing energy having predetermined wave-lengths and rejecting other wavelengths.
An elontage reflector surface is located ,~ internally of the envelope and is arranged to reflect light received through the upper transparent surface onto the two-way tube. The locus of the reflector surface is designed to achieve maximum efficiency and is the shape -,' required to ensure that all incident rays reoeived into ;; 20 the envelope through the upper transparent surface)within the acceptance angle determined by the equation:
~' ~ . C = 1 ;' sin~
:''.', . "
where C is the concentration ratio (i.e., the ratio of the transverse width of the upper transparent surface to the outer circumference of the tube) and ~ is the -~';' acceptance angle, are concentrated on the two-way tube ~`' while rays outside the acceptance angle are reflected.
, .. .
The shape of the reflector surface determined by the above equation represents the maximum efficiency . , , of the collector. In accordance with the present . . ~
' :
''' ' , ' ~ ' . ., , ,. ~
~ 7946 .. invention, the locus o~ the rePlector surface i.s the shape required to ensure that from ahout 75% of, preferably . from about 90% of, to less than the maximum efficiency of the collector is realized. Although there is a decrease in efficiency, advantages in truncation o the reflector . surface, with consequentially reduced material costs, result.
. . .
Accordingly, the present invention provides a . solar collector comprising: an outer evacuated elongate ;- 10 envelope having an upper transparent surface to admit ~- light rays to the envelope, a tube extending in the envelope from one end thereof towards the other for conveying fluid to be heated into the collector and for removing heated fluid from the collector, the tube comprising a concentrically-arranged pair of inner and _, , :~.- . outer tubes extending from one end of the envelope ~ substantially to the other and an end closure at the other ,;:;,;
. end constructed to define a flow channel from the inner to the outer tube or vice versa, whereby fluid to be ... ` 20 heated enters the collector from the same end as heated ................ fluid is removed from the collector, a selectively ~` absorbing surface on the tube for selectively absorbing ., ~ .
:.; . energy having predetermined wavelengths and rejecting .. . .
.. other wavelengths, and an elongate reflector surface . .~ .
located internally of the envelope and arranged to .
; reflect light received through the transparent surface onto the tube, the upper transparent surface and the tube ., ,.~
being dimensioned to provide a concentration ratio which is the ratio of the transverse width of the upper trans-~ . 30 parent surface to the outer circumference of the tube and `. has a value greater than about 0.5, the locus of the ~: - 3 -. .
.. , ~ .
~ .
. . .
- 10~17946 reElec~.or sur~ace b~iny ~he sh~p~ requ:ir~d to ~nsure that :
from about 75% oE to less than -the maximum eficiency of the coll~ctor is realized, the maximum efficiency being .
~; provided by the shape required to ensure that all incident .
rays received into the envelope through the upper trans-~ parent surface within the acceptance angle determined by ~ .
;. the equation~
C=
sin~
where C is the concentration ratio and ~ is the acceptance .
angle, are concentrated on the tube while rays outside the acceptance angle are reflected. - :
The invention is described further, by way o illustration, with reference to the accompanying drawings, . -.
wherein: .
, . ~ . , .:
; Figure 1 is a perspective view, with parts cut away, illustrating a solar coIlector constructed in accor- .
., dance with this invention; and .
Figure 2 is a section taken on line 2-2 of ~.
. 20 Figure 1. .-.. ~ In the drawings, a solar collector 10 is pro- ¦
~ vided in the form of an elongate, integral generally tub- ~ 1 r::; ular element, preferably fabricated wholly of glass or .-. other convenient material, having a tubular end portion ~ 12.
A tube 14 extends generally axially of the collector 10 and the portion of the tube 14 extending .~.
into the collector 10 beyond the tubular end portion 12 is surrounded by an axially extending parallel tubular .. 30 portion 16 integral with and of the same diameter as the ' :'.
... .
.,:
. .. : - ,, ~ , -~7946 :
tubular end portion 12 at one end and closed at the other !
beyon~ the ~xtremi ty oE th~ ~ube ~ o d~E:Lne a :Eluid .Elow path ~hrough the collector 10. rrhe ~luid flow pakh extends ~ internal~y ~ the tube 14 and then between the internal sur-;~ face of the tubular portion 16 and the outer surface o~ the tube 14, or vice versa, depending on the direction of fluid flow.
An outer envelope 18 surrounds and encloses the tube 14 and the tubular portion 16 and is integral with the tubular end portion 12. The space 20 between the ~uter envelope 18 and the tubular portion 16 is evacuated.
The outer envelope 18 is contoured as shown in the sectional view of Figure 2 and has a relatively flat top ~' surface portion 22 to allow entry of sun rays into the collector 10.
The remainder of the inner surface of the outer envelope 18 is coated with a highly reflective material 24, such as silver, to reflect sun rays entering the collector 10 through the top surface 22 and impinging on the envelope inner surface.
, :~
The tubular portion 16 has a high absorbance at all incident angles in the spectral wavelength of 0 to 3 x 10 6 meters. In order to decrease heat losses, the absorbance for higher wavelengths should be low. The selective absorbance , may be achieved by coating the outer surface of the tubular;~ ., ~` portion 16 with a suitable material, such as chrome black.
The circular cross section of tube 16 may be replaced by ..~1 ~ any other desired cross-sectional shape.
., .
In the collector 10, the concentration ratio (C) refers to the relative dimensions of the radiation-receiving portion and radiation-absorbing portion of the collector, ,.;.
.: , .~., ~ ., . ~,; .
~;
- .
. . .
. , , , . -.... . .
., ~- 10`~79"~
while the acceptance ang:Le (~) reEexs to ~he angle withln which all rays entering the collector 10 through the radia-tion-receiving portion are absorbed by the radiation- ¦
absorbing por~ion of the collector while rays entering the ~- collector through the radiation-receiving portion outside that angle are reflected.
Referring to Figure 2, the concentration ratio (C) ; of the collector is determined by the ratio: ¦
C = Entrance Aperture Width = A
Absorber Tu~e Circumference 2 ~ R
~ lO The acceptance angle (~) is the angle to the vertical ; axis within w~ich all rays entering the collector through the upper surface 22 are absorbed by the two~way tube 16 while .. , , rays outside that angle are reflected back without being absorbed. The limiting condition far acceptance of rays ',l for absorption is a ray which is reflected by the reflecting :,. .
surface to pass tangentlally to the two-way tube 16, as illustrated.
; In a collector of maximum efficiency, the ~'! acceptance angle (0) is determined by the concentration ratio (C~ in accordance with the equation:
. i ~C =
; sin and the locus of the reflecting surface 24 of the collector ;~.
is the shape corresponding to that equation.
It will be seen from the above equations that, as the concentration ratio (C) increases, the acceptance angle (~) decreases. The value of the acceptance angle will determine the length of time during a given day when .. . .
the collector will absorb light rays, assuming that the collector is located in a fixed relationship with respect to the sun mavement. The value of the concentration ratio will determine the temperature rise attainable in the .;, .
, i~ ~) :
'' ' ' . , .
.
7~34~
;
two-way tube during the time that rays are accepted :~ within the acceptance ~ngle, with an increase in concentra-tion ratio leading to an increase in temperature under otherwise flxed conditions.
; The minimum concentration ratio for the -` ` collector is about 0.5 and the upper limit of concentration .
ratio for a fixed location system is about 10. If the ~ collector is mounted to track the sun's movement on a . .
' daily basis or if the sun's rays can be concentrated :~
~ 10 within the narrow acceptance angle which exists at these :~
`i high concentration ratios, then the concentration ratio : may exceed 10, although it will rarely exceed 50.
,jj .
i:l Preferably, the concentration ratio is about `~~ 1.0 to about 3.0, most preferably about 1.5 to about 2.0, .
which provides a good balance of acceptance angle and :
' concentration ratio, so that the collector has a sufficiently wide acceptance angle to absorb rays over a .
1 long period of daylight hours, while at the same time ~
:: providing a good heating effect on the fluid flowing .
.. 1 . .
through the collector. .
If the physical height of the body portion 18 ~; is decreased without otherwise altering the shape of the , reflector surface 24, as shown in the modification of Figure 2 wherein the dotted outline represents the locus ,~; i ~` of maximum efficiency and the solid outline represents ~:
. ; .
; the decreased height body, the concentration ratio is decreased and thus leads to a less than maximum efficiency of collector 10.
. ~
: Since, however, the upper portions of the reflec- !
.. 30 ting surface 24 adjacent the upper surface 22 are almost , , parallel and have only a minor effect on the rays which ,.."~
.... .
:, . ;, .
. .
.: - .
g~6 :
are absorb~d by the tube 16, the loss in e~Elciency nee~
~ only be minor, while the material saving achle~ed thereby : ~` is considerabl~. ¦
In this invention, the maximum loss of e~ficiency rom ideal conditions is about 25~, while preferably the loss o~ ef~iciency tolerated on truncation is less than about .
10%. -The outer envelope 18 of the collector preferably is comprised of (1) an upper surface portion formed of ~, 10 glass and constituting the transparent surface and (2) a lower body portion constructed of vitreous ceramic :
. .~ . , 's` material formed from clay and various fluxes. Vitreous.
, ceramic materials are inexpensive and readily available, :
and can be ~ormed into shaped objects by molding or , axtrusion, making them ideal for formation of an integral molded or extruded lower body portion.
~ The collectors of this invention may achieve a ,I photovoltaic function by producing an electrical output from collected solar energy. The two-way tube 16 may be -coated with light energy actuable electricity generating material layers which communicate through suitable elec- ¦
' trical connection to exterior of each collector 10.
.,~
...
.
: ." .
'`', ~ -:
., : :
~:.,. ;
,. i , , ` ;'~ .
, . ~ .
, ~; ..
~ - 6B
, ' ' '?~'~lJ`
: ~ ~;i rj .~.
"
'.. ;, ' . , -' ' ' . ' ~ ~ .: .
'~'; ', '' ' ' ~ ' , :, . ~ . .. .
Claims (5)
1. A solar collector comprising:
an outer evacuated elongate envelope having an upper transparent surface to admit light rays to the envelope, a tube extending in the envelope from one end thereof towards the other for conveying fluid to be heated into the collector and for removing heated fluid from the collector, said tube comprising a concentrically-arranged pair of inner and outer tubes extending from one end of the envelope substantially to the other and an end closure at the other end constructed to define a flow channel from the inner to the outer tube or vice versa, whereby fluid to be heated enters the collector from the same end as heated fluid is removed from the collector, a selectively absorbing surface on said tube for selectively absorbing energy having predetermined wavelengths and rejecting other wavelengths, and an elongate reflector surface located internally of the envelope and arranged to reflect light received through the transparent surface onto said tube, said upper transparent surface and said tube being dimensioned to provide a concentration ratio which is the ratio of the transverse width of the upper transparent surface to the outer circumference of the tube and has a value greater than about 0.5, the locus of said reflector surface being the shape required to ensure that from about 75% of to less than the maximum efficiency of the collector is realized, said maximum efficiency being provided by the shape required to ensure that all incident rays received into the envelope through the upper transparent surface within the acceptance angle determined by the equation:
where C is the concentration ratio and .theta. is the acceptance angle, are concentrated on said tube while rays outside the acceptance angle are reflected.
an outer evacuated elongate envelope having an upper transparent surface to admit light rays to the envelope, a tube extending in the envelope from one end thereof towards the other for conveying fluid to be heated into the collector and for removing heated fluid from the collector, said tube comprising a concentrically-arranged pair of inner and outer tubes extending from one end of the envelope substantially to the other and an end closure at the other end constructed to define a flow channel from the inner to the outer tube or vice versa, whereby fluid to be heated enters the collector from the same end as heated fluid is removed from the collector, a selectively absorbing surface on said tube for selectively absorbing energy having predetermined wavelengths and rejecting other wavelengths, and an elongate reflector surface located internally of the envelope and arranged to reflect light received through the transparent surface onto said tube, said upper transparent surface and said tube being dimensioned to provide a concentration ratio which is the ratio of the transverse width of the upper transparent surface to the outer circumference of the tube and has a value greater than about 0.5, the locus of said reflector surface being the shape required to ensure that from about 75% of to less than the maximum efficiency of the collector is realized, said maximum efficiency being provided by the shape required to ensure that all incident rays received into the envelope through the upper transparent surface within the acceptance angle determined by the equation:
where C is the concentration ratio and .theta. is the acceptance angle, are concentrated on said tube while rays outside the acceptance angle are reflected.
2. The solar collector of claim 1 wherein said reflector surface locus is in the shape required to ensure that no less than about 90% of the maximum efficiency of the collector is realized.
3. The solar collector of claim 1 or 2, wherein said concentration ratio has a value of about 1.0 to about 3Ø
4. The solar collector of claim 1 wherein said outer envelope is comprised of (1) an upper surface portion formed of glass and constituting said transparent surface and (2) a lower body portion formed of vitreous ceramic material.
5. The solar collector of claim 1 wherein said tube has light-energy actuable electricity generating material layers provided thereon and electrical connectors extending from said layers externally of the envelope.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA315,800A CA1087946A (en) | 1977-12-23 | 1978-11-03 | Solar energy collection system |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA293,819A CA1047343A (en) | 1977-12-23 | 1977-12-23 | Solar energy collection system |
| CA315,800A CA1087946A (en) | 1977-12-23 | 1978-11-03 | Solar energy collection system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1087946A true CA1087946A (en) | 1980-10-21 |
Family
ID=25668618
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA315,800A Expired CA1087946A (en) | 1977-12-23 | 1978-11-03 | Solar energy collection system |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1087946A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2621108A2 (en) * | 1984-07-02 | 1989-03-31 | Emmanuel Emile Michel | Solar generator of the "thermal influence by irradiation" (I.N.T.I.) type |
-
1978
- 1978-11-03 CA CA315,800A patent/CA1087946A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2621108A2 (en) * | 1984-07-02 | 1989-03-31 | Emmanuel Emile Michel | Solar generator of the "thermal influence by irradiation" (I.N.T.I.) type |
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