CA1110938A - Solar energy collector - Google Patents
Solar energy collectorInfo
- Publication number
- CA1110938A CA1110938A CA293,284A CA293284A CA1110938A CA 1110938 A CA1110938 A CA 1110938A CA 293284 A CA293284 A CA 293284A CA 1110938 A CA1110938 A CA 1110938A
- Authority
- CA
- Canada
- Prior art keywords
- panel
- header
- headers
- collector
- liquid
- 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
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- 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
- F24S10/50—Solar heat collectors using working fluids the working fluids being conveyed between plates
- F24S10/502—Solar heat collectors using working fluids the working fluids being conveyed between plates having conduits formed by paired plates and internal partition means
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- 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
- F24S10/50—Solar heat collectors using working fluids the working fluids being conveyed between plates
- F24S10/501—Solar heat collectors using working fluids the working fluids being conveyed between plates having conduits of plastic material
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24S—SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
- F24S80/00—Details, accessories or component parts of solar heat collectors not provided for in groups F24S10/00-F24S70/00
- F24S80/30—Arrangements for connecting the fluid circuits of solar collectors with each other or with other components, e.g. pipe connections; Fluid distributing means, e.g. headers
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- 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
ABSTRACT OF THE DISCLOSURE
A solar energy collector is described for use in a solar heating system. According to one aspect of the inven-tion, the collector includes first and second headers, each including an internal chamber disposed about a longitudinal axis and a slot communicating with said chamber and defined by opposed generally parallel surfaces which extend outwardly from said chamber and longitudinally of the header. An extruded plastic panel extends between the headers and de-fines a plurality of open-ended passages extending from end to end of the panel and along which liquid can flow for heating by solar radiation. Opposite end portions of the panel are received in the slots in the respective headers with upper and lower surfaces of each said portion in surface-to-surface contact with said opposed parallel surfaces defining the slot in the relevant header, and the panel is sealed to the headers in liquid-tight fashion. The slots in the headers are dis-posed in a common plane offset from and parallel to a plane containing the axes of said chambers of the respective headers so that, when the collector is disposed on a support surface in use, the headers can be positioned with the panel closely adjacent to said surface and presenting an air gap of minimum height between the panel and said surface so as to minimize exposure of the panel to wind damage in use.
A solar energy collector is described for use in a solar heating system. According to one aspect of the inven-tion, the collector includes first and second headers, each including an internal chamber disposed about a longitudinal axis and a slot communicating with said chamber and defined by opposed generally parallel surfaces which extend outwardly from said chamber and longitudinally of the header. An extruded plastic panel extends between the headers and de-fines a plurality of open-ended passages extending from end to end of the panel and along which liquid can flow for heating by solar radiation. Opposite end portions of the panel are received in the slots in the respective headers with upper and lower surfaces of each said portion in surface-to-surface contact with said opposed parallel surfaces defining the slot in the relevant header, and the panel is sealed to the headers in liquid-tight fashion. The slots in the headers are dis-posed in a common plane offset from and parallel to a plane containing the axes of said chambers of the respective headers so that, when the collector is disposed on a support surface in use, the headers can be positioned with the panel closely adjacent to said surface and presenting an air gap of minimum height between the panel and said surface so as to minimize exposure of the panel to wind damage in use.
Description
3~3 This invention relates to a solar energy collector for use in a solar heating system.
Solar energy collectors have previously been pro-posed in which each collector comprises two headers joined by an extruded plastic panel having multiple tubular passages through which liquid can be passed and in which the liquid is heated when the panel is exposed to solar radiation.
Examples of such collectors are shown in United States Defensive Publication T952,004 (Brackman) and in United States ~atent No. 3,934,323 (Ford et al). In the Brackman collector, the panel is attached to the headers by a poly-propylene sealer, while in the Ford et al collector, the panel is heat welded to the headers.
A problem encountered with collectors of the gen-eral type discussed above is that they are susceptible to wind damage in use. Thus, in a typical solar heating system, an array of solar energy collectors is mounted on an in-clined roof or other support surface for optimum exposure to solar radiation. The headers of each panel lie on the support surface and the panel is spaced above the surface, as a result of which air can flow below the panel and may tend to lift it from the surface in windy conditions.
Another problem with prior art solar energy collectors derives from the fact that the collectors are essentially exposed to high levels of solar radiation in use. Since many plastic materials deteriorate when ex-posed to solar radiation for extended periods, the materials 28 from which the units are made must be carefully selected.
~ ' g3~3 This in turn makes for difficulty in providing for effective, liquid-tight sealing of the panel to the headers of the unit since many conventional sealing materials do not readily form effective, durable seals with plastic materials which are relatively inert with respect to solar radiation.
An object of the present invention is to provide an improved solar energy collector for use in a solar heating system.
According to one aspect of the invention, the collector includes first and second headers, each including an internal chamber disposed about a longitudinal axis and a slot communicating with said chamber and defined by opposed generally parallel surfaces which extend outwardly from said chamber and longitudinally of the header. An extruded plastic panel extends between the headers and de-fines a plurality of open-ended passages extending from end to end of the panel and along which liquid can flow for heatin~ by solar radiation. Opposite end portions of the panel are received in the slots in the respective headers with upper and lower surfaces of each said portion in surface-to-surface contact with said opposed parallel surfaces de fining the slot in the relevant header, and the panel is sealed to the headers in liquid-tight fashion. The slots in the headers are disposed in a common plane parallel to ;, a plane containing the axes of said chambers of the respec-tive headers, and offset from said plane by a distance less ~ than the distance between said longitudinal axis of each i header and the wall of said internal chamber at the position of said slot.
3~3 In order that the invention may be more clearly understood, reference will now be made to the accompanying drawings which illustrate a number of embodiments of the invention by way of example, and in which:-Fig. 1 is a perspective view of a solar energycollector according to a first embodiment of the invention, in association with a second similar collector;
Fig. la is a diagrammatic longitudinal sectional view through the collector shown in Fig. l;
Fig. 2 is a partly sectioned perspective view of part of one end of the collector of Fig. l;
Fig. 3 is a sectional view on line III-III of Fig. 2;
Fig. 4 is an exploded perspective view of one end of one of the headers of the collector shown in the previous ,' views;
Fig. 5 is a detail sectional view on line V-V
of Fig. l;
Fig. 6 is a perspective view of a solar energy 20 collector according to a second embodiment of the invention, the collector being shown in a position of use on a roof surface;
Fig. 7 is an exploded perspective view of a detail of Fig. 6;
Fig. 8 is an exploded perspective view of one end of one of the headers of the unit shown in Fig. 6;
Fig. 9 is a detail view in the direction of arrow A in Fig. 8; and, Fig. 10 is a longitudinal sectional view through 3~3 a solar eneryy collector accoding to a further embodiment of the invention.
Referring first to Fig. 1, a solar energy collector according to a first embodiment of the invention is generally denoted 20 and a second similar collector coupled to col-lector 20 is shown at 201. Collector 20 includes first,and second headers 22 and 24 and an extruded plastic panel 26 which extends between the headers. The cross-sectional shape of panel 26 is visible in E'ig. 2 and it will be seen that the panel is of thin, rectangular cross-section and defines a plurality of open-ended passages 28 which extend from end to end of the panel. Panels of this type are commercially available for use as packaging boards. In this embodiment, panel 26 is extruded in a polypropylene co-polymer to which particles of carbon black have been added to give the panel a black colour and thereby impart good solar radiation ab-sorbing properties.
The two headers 22 and 24 of the collector 20 are essentially the same and therefore only header 24 will be described. Header 24 includes a main centre section 30 of a length sli~htly greater than the width of panel 26, and two end fitments 32 and 34 attached to the outer end portions of the main centre section 30. In this embodi-- ment, section 30 is 49 inches long and panel 26 is 48 inches in width. The panel is centralized with respect to the length of section 30 so that the section protrudes by about half an inch beyond each end of panel 26. The cross-sectional 28 shape of the main centre section 30 of header 24 is visible i38 in Figs. 2 and 4. Section 30 is of uniform cross-sectional shape throughout its length and includes a generally cylindri-cal portion 36 which defines a cylindrical internal cavity 38, and two wall portions 40 and 42 which project outwardly from portion 36 parallel to one another and which extend longitudin-ally of section 30. A slot 44 is defined between wall portions 40 and 42 and is offset from the longitudinal axis X-X
of the cylindrical ahamber 38 of section 30 so as to extend generally tangentially with respect to chamber 38.
Referring now particularly to Fig. 3, each header includes sealing strips 46 and 48 which are secured by ad-hesive to the inner surfaces of the respective wall portions 40 and 42 of section 30. The sealing strips are made of closed-cell neoprene rubber and have inner surfaces 50 and 52 respectively which define slot 44. The slot is dimen-sioned so that an end portion of panel 26 inserted into slot 44 is closely received between the sealing strips 46 and 48.
The panel is held in place by a series of self-tapping screws, one of which is indicated at 54 in Fig. 3, which are in-serted through the wall portions 40 and 42, the sealing strips 46 and 49 and the panel 26. In this embodiment, the screws are spaced at approximately 2 inch intervals across the width of panel 26.
It will be appreciated that tightening of the screws 54 in manufacture of the collector draws the wall portions 40 and 42 of the header centre section 30 inwardly to effect liquid-tight sealing engagement between the neo-prene sealing strips 46, 48 and the end portions of panel 26. A similar sealing arrangement is provided for the main centre section of header 22 although this arrangement has g3~3 not been specifically illustrated in the drawings.
Fig. la is a diagrammatic view of the solar col-lector 20 shown in Fig. 1 mounted on an inclined roof surface 56. It will be noted that the headers 22 and 24 are arranged so that the slot 44 in the centre section 30 of header 24 -lies in a common plane, denoted Pl, with the corresponding slot 58 of the centre section of header 22 and that this plane is offset from and parallel to a plane, denoted P2, containing the axis X-X of internal chamber 38 of header 10 section 30, and the corresponding longitudinal axis Y-Y
of header 22. Collector 20 is arranged on the roof surface 56 so that the panel 26 is disposed closely adjacent to the surface and presents an air gap of minimum height be-tween the panel and the surface so as to minimize exposure of the panel to wind damage in use. The height of the air gap is in fact equal to the height of the lower wall portion 42 of the main section 30 of header 24. In a prac-tical embodiment, this height would be of the order of i 0.250 inches. From the headers, the panel does in fact - 20 curve downwardly into contact with the support surface 56 and is held in contact with the surface as will be described.
Accordingly, an air gap effectively exists only below the portions of the panel 26 ad~acent the headers 22 and 24.
- Another advantage which derives from applicant's form of header is that internal pressure of liquid entering panel 26 from a header tends to urge the upper and lower walls of the panel outwardly against the sealing strips 46 and 48, thereby increasing sealing efficiency between the panel and the header.
As indicated previously, header 24 also includes ~ ~ .
end fitments 32 and 34. Fitment 34 is shown in detail in Fig. 4 is an exploded position with respect to an end of the header centre section 30 and panel 26. Fitment 34 is a one-piece plastic molding and includes an inner end por-tion 60 shaped to define a recess 62 which is complementary to and dimensioned to closely receive the opposing end por-tion of header centre section 30. The depth of recess 62 is chosen to be substantially equal to the distance by which panel 26 is inset from the end of header section 30 so that the fitment in fact buts against panel 26 when in position on the end portion of section 30. The position of the fitment at this time is shown in chain dotted line at 341 in Fig. 4. Fitment 34 also includes an integral cylindrical extension 64 which projects outwardly from the inner end portion 60 and which is co-axial with the gener-ally cylindrical portion 36 of the main header section 30 when the fitment is in position on the section. Fitment 34 further includes an integral flange 66 which is disposed parallel to the bottom wall portion 42 of section 30 when the fitment is in place. Flange 66 is formed with an open-ing 68 to receive a screw for attaching the header to a ~ support surface as will be described.
; In order to ensure effective sealing of the fit-ment 34 to header section 30, a specially shaped sealing element, also of neoprene rubber, is positioned in the slot 44 of header section 30 between the outer side face of panel 26 and the end of section 30. This element is denoted 70 in Fig. 4 and is secured in place in slot 44 by adhesive.
It will of course be appreciated that the fitment 32 at the other end of the header centre section 30 is essen-iy~
tially the same as fitment 34, although of opposite hand,and that similar sealing arrangements are provided at that end oE section 30.
In this embodiment, both the header centre section 30 and the fitments 32 and 34 are made of a rigid ABS plas-tic materia]. Section 30 is a one-piece extrusion of uni-form cross-sectional shape throughout its length and is in fact manufactured in continuous lengths which may be cut to size as appropriate. The fitments 32 and 34 on the other hand are injection molded as one-piece uniis.
The fitments 32 and 34 are secured to the header centre section 30 using a çonventional MEK (methyl-ethyl-ketone) solvent. The assembly sequence is to first of all secure the panel 26 in the slot in the main header section 30 with the interposition of the neoprene sealing strips 46 and 48, and to secure the sealing element 70 (and the corresponding element at the other end of the section) into the end of the slot. Recess 62 in fitment 34 and the outer end portion of section 30 to be received in the recess are then both coated with MEK solvent and the fitment is assembled to the section as indicated by arrow 72 in Fig. 4. Fitment 32 is assembled to the opposite end of section 30 in similar fashion.
; As indicated previously, the header 22 at the upper end of panel 26 is essentially the same as header 24.
In Fig. 1, the end fitments of header 22 are denoted 74 and 76. Each fitment includes a flange similar to the flange 66 of fitment 34 (see Fig. 4) formed with an opening to receive a screw. Accordingly, four attachment points are provided for each panel in association with the end fitments _ g _ 3~3 of the respective headers. The four attachment points for the panel 26 shown in Fig. 1 are denoted respectively 78, 80, 82 and 84. The panel may be held in place by screws, nails or the like extending through the openings in the fitments at these attachment points and secured to the roof or other support surface on which the collector is positioned.
As will be explained subsequently in connection with the succeeding embodiment, in some situations, it may be de-sirable to secure to the surface the top header only in order to allow for longitudinal expansion and contraction of the panel under varying temperature conditions. However, the particular method of attachment will be determined in accordance with the discretion of the installer; not all of the available attachment points will necessarily be used in practice.
Also shown in association with panel 26 in Fig. 1 are four hold-down tabs 86. One of the tabs is shown in vertical cross-section in Fig. 5. It will be seen that the tab includes a flat, generally rectangular upper portion 88 which lies on top of the panel, and an integral collar portion 90 formed with an opening 92 to receive a screw such as that indicated at 94. Portion 88 is disposed flush with the top of collar portion 90. Tab 86 also includes à recess 96 defined between portion 88 and collar portion 90, which recess is of a height corresponding to the thick-ness of panel 26. It will be appreciated that, when the hold-down tab is secured to the roof surface 56 by screw 94, panel 26 will be held flat against the roof and will be re-strained against outward movement under the effect of wind.
Nevertheless, the panel will be free to slide longitudinally in the recess 96 in the hold-down tab as the panel expands and contracts due to temperature variations.
The solar collector is connected to the other com-ponents of the solar heating system in which it is used by way of the end fitments of the headers. For example, in Fig. 1, unit 20 is shown coupled to a second similar collector 201. The collectors are positioned side-by-side as shown and adjacent end fitments are coupled together by flexible vinyl tubes 98 and 100. A further, similar tube is shown at 102 in association with the end fitment 34 at the bottom right hand end of panel 26. Tube 102 is di-mensioned to fit closely over the tubular portion 64 of fit-ment 34 and is held in place on portion 64 by means of a gear clamp 104. A second similar clamp is shown at 106 for coupling the opposite end portion of tube 102 to another part of the system. It will be noted that portion 64 has a thickened peripheral rim 108 at its outer end over which tube 102 is fitted and behind which gear clamp 104 is tightened onto portion 64. This makes for secure, leak-free coupling of the tube to the fitment.
It will of course be appreciated that, although the two collectors 20 and 201 have been shown closely ad-jacent to one another, this is not essential. The vinyl tubes may be of any length and, since they are flexible, can accommodate virtually any relative positioning of adjacent collectors or other parts of the system. Thus, the collector will be connected to other associated equip-ment (not shown) such as pumps, valves, vacuum breakers and the like by way of similar flexible vinyl tubes. Also, it will be appreciated that the collectors need not be con-nected top heacler to top header and bottom header to bottomhe~der as shown in Fig. 1. Where the collector is used in a system in which incoming liquid to be heated is introduced into the bottom header and flows upwardly through the panel, it may be desirable to connect the top header of one col-lector to the bottom header of the adjacent collector so that the liquid flows upwardly through the panels of both collectors. Such an arrangement may be readily effected using flexible vinyl tubes of appropriate length.
Where it is necessary to blank off an end of a header, a plug or bung is secured in the outer end of the tubular portion 64 of the relevant header fitment. A
suitable plug is shown at 110 in association with fitment 76 at the upper right hand end of collector 20 in Fig. 1.
The plug is made of rubber and is force fitted into the outer end of the tubular portion of the fitment. For tem-porary installations, a force fitted plug will normally be adequate. In a permanent installation, however, the plug will be secured in place by adhesive.
Referring to Fig. 2, reference numeral 112 denotes an insert intended to be located in an end portion of one of the passages 28 in panel 26 for the purpose of restrict-ing liquid flow therethrough. One of these inserts is in fact provided in each end of each passage 28 in the panel.
Others of these inserts are visible insid~ the centre header section 30 in Fig. 2 and are indicated in dotted outline at 112 in panel 26 in Fig. 1. Each insert is of elongate rectangular shape and is of square shape in cross-section, having a longitudinally extending bore 114. The inserts are molded in an ABS plastic materiàl so that the panel re taining screws 54 can pass throu~h them if necessary. In any event, the purpose of the inserts 112 is, as indicated previously, to restrict the flow of liquid through the panel so that the liquid is in effect slowed down in its travel and remains within the panel 26 for a time sufficient to allow it to absorb a reasonable amount of solar energy.
The inserts 112 also serve the function of supporting the upper and lower walls of panel 26 during tightening of the panel retaining screws 54 to guard against accidential crushing of the panel due to overtightening of the screws.
However, it has been found in practice that the inserts are not essential for this purpose and that there is fairly minimal risk of crushing the panel if normal manu-facturing precautions are taken. Neither are the inserts essential for restricting liquid flow through the panel.
For example, if the collector is used in a closed circula-tion circuit, flow of liquid through the panel can be con-trolled by appropriately controlling the delivery rate of the purnp in the circuit. Alternatively, particularly where the unit is used in an open circuit, an adjustable restrictor valve can be provided in the discharge from an individual collector or array of collectors to provide a back pressure for controlling liquid flow. This arrangement has the ad-vantage that the valve can he adjusted to control the flow rate of the liquid in accordance with prevailing ambient temperature conditions and operating requirements.
Reference will now be made to Figs. 6 to 9 of the drawings which illustrate an alternative embodiment of the invention. Since many of the principal parts of the collector shown in these figures are very similar to parts g3~3 shown in Figs. 1 to 5, prime~ refcrence numerals have been used in Figs. 6 to 9 to indicate such parts. Thus, the collector itself is generally denoted 20' in Fig. 6 and is shown mounted on a roof surface 56'. The unit includes upper and lower headers 22' and 24' respectively and a panel 26'. Each header includes a main centre section and end fitments which, while they are basically similar to the section and fitments shown in the previous figures, incor-porate eertain modifications which will be described in eonnection with Figs. 8 and 9. However, reference will first be made to Fig. 7 in describing an alternative form of panel hold-down arrangement used in this embodiment.
Thus, the hold-down tabs 86 of the previous embodiment have been replaced by tabs denoted 116 in Fig. 6 and associated hold-down straps 118.
Referring to Fig. 7, eaeh hold-down tab ineludes a generally rectangular portion 120 and an integral eollar portion 122. A serew opening 124 is provided in the eollar portion 122 for reeeiving a serew 126 to be driven into the roof surface 56'. The tab is formed below portion 120 with a right angular reeess 128 of a height eorresponding to the thiekness of panel 26' arranged so that, when the tab is serewed to the roof surfaee, the panel is retained in reeess 128. The tab is designed to allow the panel to slide in recess 128 as it expands and eontraets due to temper-ature ehanges as deseribed in eonneetion with the previous embodiment. In faet, the partieular eolleetor shown in Figs. 7 to 9 is intended to be attaehed to the roof sur-faee by the upper header 22' only; that is, attaehment points 82' and 84'. The bottom header 24' will be free to move as the panel expands and contracts longitudinally as indicated by arrows 130. The hold-down straps and tabs merely hold the panel against the roof surface.
The straps 118 are of thin rectangular shape in cross-section and both they and the tabs 116 are made of an ABS plastic material. At its outer end, each tab is formed with a screw opening 132 which aligns with the opening 124 in the appropriate hold-down tab 116. Thus, as seen in Fig. 7, a single screw 126 is used to retain both an end of the relevant strap 118 and the tab itself. Lo-cating ribs 134 are provided on the upper surface of tab 116 and the strap fits between the ribs.
Referring now to Figs. 8 and 9, the centre section 30' of header 24' is of similar shape to the header section 3~ described in connection with the previous embodiment.
However, instead of separately attached neoprene sealing strips 46 and 48, section 30' incorporates integrally molded sealing strips 136 and 138 which define the walls of slot 44'. Section 30' is extruded in one piece complete with the sealing strips 136 and 138 by a known extrusion technique. The generally cylindrical portion 36' of sec-tion 30' and the upper and lower wall portions 40' and 42' which define slot 44' are made of a rigid vinyl material, while the sealing strips 136 and 138 are made of a soft vinyl and are compressible for sealing against panel 26'.
Further, a plurality of parallel, longitudinally extending sealing ribs 136a and 138a are molded into the sealing strips to provide for improved sealing between the strips and the panel 26'. As in the previous embodiment, the panel is retained in slot 44' by self-tapping screws 54'.
A further modification compared with the previous embodiment is that an integral sealing formation 140 is molded into the recess 62' in end fitment 34' and replaces the sealing element 70 used in the end of the centre header section (See Fig. 4). Formation 140 is positioned to fit into the end of slot 44' and seal against the relevant edge of panel 26'. As in the previous embodiment, an MEK solvent is applied both to section 30' and to end fitment 34' for securing the fitment to the section. Solvent will also be applied to formation 140 and inside the end of slot 44' at this time to ensure firm sealing of the end fitment to the section. Also, for added security of fixing, three openings 142 are provided in the inner end portion 60' of fitment 34' for receiving self-tapping screws 144 which are driven into the end portion of section 30'.
Finally, Fig. lO shows a further embodiment of the invention which may be used in association with either of the previously described embodiments to provide improved heating efficiency.
Fig. lO shows a longitudinal sectional view through a collector according to this embodiment. The headers and panel are as shown in connection with the embodiment of Figs. l to 5 and are denoted by double primed reference num-erals corresponding to the numerals used previously. For clarity of illustration, the end fitments of the headers have not been shown. The collector shown in Fig. 10 has been designed to take advantage of the so-called "greenhouse effect" and includes a sheet of transparent plastic material of the type sold under the trade mark MYLAR which is posi-tioned above and at a spacing from panel 26" so~as to pro-3~3 vide an air gap between the panel and the sheet. The MYLAR sheet is denoted 146 in Fig. 10 and is positioned with its end portions directly on top of panel 26" so that the sheet 146 is in effect trapped between the panel and the upper sealing strip 46" in the slots in the respective headers.
The panel retaining screws 54" also penetrate the MYLAR
sheet. The air gap between the MYLAR sheet 146 and panel 26" is provided by a series of protuberances or "bumps"
148 on the upper surface of panel 26". The protuberances are distributed in a 2 inch square grid pattern over the upper surface of the panel and are formed by drops of a hot melt adhesive. The side margins of sheet 146 are free so that the air gap between the panel and the sheet is open at its sides.
It will be appreciated that the presence of the MYLAR sheet will cause solar radiation incident on the panel to be trapped inside the air gap, causing a "greenhouse effect" to take place and effectively increasing the heat transferred to the liquid in the solar collector.
As indicated previously, the embodiment of Fig.
10 may also be used in association with a collector having headers and a panel of the form described with reference to Figs. 6 to 9. In that event, the hold-down straps 118 may sexve to space the MYLAR sheet 146 from the surface of the panel, thereby avoiding the need for the protuberances 148. It is further to be understood that, while a sheet of MYLAR plastic has been found to be satisfactory in practice, sheets made of other materials transparent to infrared radiation may alternatively be employed.
It should also be noted that, while the preceding 3~3 description relates to specific embodiments of the inven-tion, many modifications are possible within the broad scope of the invention. For example, the particu]ar plastic materials specifically referred to above are not to be considered as essential and may be replaced by suitable alternatives. Also, it is to be noted that, while the solar energy collectors described herein have been designed primarily for use in solar heating systems for swimming pools, there is no limitation in this and that the units may be used in other types of solar heating system. The systems themselves are conventional and it is believed unnecessary to describe them here. Nevertheless, it is to be noted that such systems may include both closed circulation cir-cuits using glycol based liquids and incorporating heat exchange means for transferring collected heat to another heat storage medium, and systems in which water circulates through the solar energy collector(s), and is used directly, e.g. in a swimming pool.
In the preceding description, the headers are described as being generally of hollow cylindrical shape.
While this particular shape may be preferred for ease of manufacture, installation and for promoting smooth flow of liquid through the header, it is to be understood that there is no limitation to this particular shape. Further, while the headers are described as comprising a centre sec-tion having separate end fitments attached thereto, there is no limitation in this regard. In another embodiment, the headers could each be molded in one piece. Where separate end fitments are provided, they could of course be attached other than by solvent welding. Suitable ad-3~3 hesives could also alternatively be used, or the end fitments could be attached by mechanical Means with the interposition of suitable gaskets.
In the embodiments described with reference to the drawings, each end fitment has a recess at its inner end which receives an end portion of the centre header section, and the panel is inset from the ends of the centre section of the header. In an alternative embodiment, the panel could extend right up to the end of the centre sec-tion and the end fitments could be molded to fit aroundthe panel.
In the drawings, the panel is shown as retained in the slot~in each header by a series of self-tapping screws. It is to be understood that this type of mechan-ical fastening of the panel to the headers is not essential.
Within the broa,d scope of the invention, the panel could be retained by adhesive in the slot in each header. The adhesive could be in the form of external beads along the joint lines between each header and the panel, or it could be applied to the co-operating surfaces of the panel and header. In this event, the slot could be formed directly in the wall of a header rather than being defined between projecting wall poriions as described. Where mechanical fastening means are employed, however, it should be noted that there is no limitation to self-tapping screws. Other alternatives are rivets and nuts and bolts.
In regard to the embodiment shown in Fig. 10 of the drawings, the plastic sheet 146 is shown trapped between the panel and the upper sealing strip 46". It is, however, to be noted that the sheet could be retained in other ways.
For example, its end portion could be disposed on top of the header wall portion 40" and held in place by the panel retaining screws 54". Also, it should be noted that the air gap between sheet 146 and panel 26" may be formed other than in the ways described. For example, the plastic sheet could be simply bowed between the two headers, provided of course it was sufficiently rigid.
Solar energy collectors have previously been pro-posed in which each collector comprises two headers joined by an extruded plastic panel having multiple tubular passages through which liquid can be passed and in which the liquid is heated when the panel is exposed to solar radiation.
Examples of such collectors are shown in United States Defensive Publication T952,004 (Brackman) and in United States ~atent No. 3,934,323 (Ford et al). In the Brackman collector, the panel is attached to the headers by a poly-propylene sealer, while in the Ford et al collector, the panel is heat welded to the headers.
A problem encountered with collectors of the gen-eral type discussed above is that they are susceptible to wind damage in use. Thus, in a typical solar heating system, an array of solar energy collectors is mounted on an in-clined roof or other support surface for optimum exposure to solar radiation. The headers of each panel lie on the support surface and the panel is spaced above the surface, as a result of which air can flow below the panel and may tend to lift it from the surface in windy conditions.
Another problem with prior art solar energy collectors derives from the fact that the collectors are essentially exposed to high levels of solar radiation in use. Since many plastic materials deteriorate when ex-posed to solar radiation for extended periods, the materials 28 from which the units are made must be carefully selected.
~ ' g3~3 This in turn makes for difficulty in providing for effective, liquid-tight sealing of the panel to the headers of the unit since many conventional sealing materials do not readily form effective, durable seals with plastic materials which are relatively inert with respect to solar radiation.
An object of the present invention is to provide an improved solar energy collector for use in a solar heating system.
According to one aspect of the invention, the collector includes first and second headers, each including an internal chamber disposed about a longitudinal axis and a slot communicating with said chamber and defined by opposed generally parallel surfaces which extend outwardly from said chamber and longitudinally of the header. An extruded plastic panel extends between the headers and de-fines a plurality of open-ended passages extending from end to end of the panel and along which liquid can flow for heatin~ by solar radiation. Opposite end portions of the panel are received in the slots in the respective headers with upper and lower surfaces of each said portion in surface-to-surface contact with said opposed parallel surfaces de fining the slot in the relevant header, and the panel is sealed to the headers in liquid-tight fashion. The slots in the headers are disposed in a common plane parallel to ;, a plane containing the axes of said chambers of the respec-tive headers, and offset from said plane by a distance less ~ than the distance between said longitudinal axis of each i header and the wall of said internal chamber at the position of said slot.
3~3 In order that the invention may be more clearly understood, reference will now be made to the accompanying drawings which illustrate a number of embodiments of the invention by way of example, and in which:-Fig. 1 is a perspective view of a solar energycollector according to a first embodiment of the invention, in association with a second similar collector;
Fig. la is a diagrammatic longitudinal sectional view through the collector shown in Fig. l;
Fig. 2 is a partly sectioned perspective view of part of one end of the collector of Fig. l;
Fig. 3 is a sectional view on line III-III of Fig. 2;
Fig. 4 is an exploded perspective view of one end of one of the headers of the collector shown in the previous ,' views;
Fig. 5 is a detail sectional view on line V-V
of Fig. l;
Fig. 6 is a perspective view of a solar energy 20 collector according to a second embodiment of the invention, the collector being shown in a position of use on a roof surface;
Fig. 7 is an exploded perspective view of a detail of Fig. 6;
Fig. 8 is an exploded perspective view of one end of one of the headers of the unit shown in Fig. 6;
Fig. 9 is a detail view in the direction of arrow A in Fig. 8; and, Fig. 10 is a longitudinal sectional view through 3~3 a solar eneryy collector accoding to a further embodiment of the invention.
Referring first to Fig. 1, a solar energy collector according to a first embodiment of the invention is generally denoted 20 and a second similar collector coupled to col-lector 20 is shown at 201. Collector 20 includes first,and second headers 22 and 24 and an extruded plastic panel 26 which extends between the headers. The cross-sectional shape of panel 26 is visible in E'ig. 2 and it will be seen that the panel is of thin, rectangular cross-section and defines a plurality of open-ended passages 28 which extend from end to end of the panel. Panels of this type are commercially available for use as packaging boards. In this embodiment, panel 26 is extruded in a polypropylene co-polymer to which particles of carbon black have been added to give the panel a black colour and thereby impart good solar radiation ab-sorbing properties.
The two headers 22 and 24 of the collector 20 are essentially the same and therefore only header 24 will be described. Header 24 includes a main centre section 30 of a length sli~htly greater than the width of panel 26, and two end fitments 32 and 34 attached to the outer end portions of the main centre section 30. In this embodi-- ment, section 30 is 49 inches long and panel 26 is 48 inches in width. The panel is centralized with respect to the length of section 30 so that the section protrudes by about half an inch beyond each end of panel 26. The cross-sectional 28 shape of the main centre section 30 of header 24 is visible i38 in Figs. 2 and 4. Section 30 is of uniform cross-sectional shape throughout its length and includes a generally cylindri-cal portion 36 which defines a cylindrical internal cavity 38, and two wall portions 40 and 42 which project outwardly from portion 36 parallel to one another and which extend longitudin-ally of section 30. A slot 44 is defined between wall portions 40 and 42 and is offset from the longitudinal axis X-X
of the cylindrical ahamber 38 of section 30 so as to extend generally tangentially with respect to chamber 38.
Referring now particularly to Fig. 3, each header includes sealing strips 46 and 48 which are secured by ad-hesive to the inner surfaces of the respective wall portions 40 and 42 of section 30. The sealing strips are made of closed-cell neoprene rubber and have inner surfaces 50 and 52 respectively which define slot 44. The slot is dimen-sioned so that an end portion of panel 26 inserted into slot 44 is closely received between the sealing strips 46 and 48.
The panel is held in place by a series of self-tapping screws, one of which is indicated at 54 in Fig. 3, which are in-serted through the wall portions 40 and 42, the sealing strips 46 and 49 and the panel 26. In this embodiment, the screws are spaced at approximately 2 inch intervals across the width of panel 26.
It will be appreciated that tightening of the screws 54 in manufacture of the collector draws the wall portions 40 and 42 of the header centre section 30 inwardly to effect liquid-tight sealing engagement between the neo-prene sealing strips 46, 48 and the end portions of panel 26. A similar sealing arrangement is provided for the main centre section of header 22 although this arrangement has g3~3 not been specifically illustrated in the drawings.
Fig. la is a diagrammatic view of the solar col-lector 20 shown in Fig. 1 mounted on an inclined roof surface 56. It will be noted that the headers 22 and 24 are arranged so that the slot 44 in the centre section 30 of header 24 -lies in a common plane, denoted Pl, with the corresponding slot 58 of the centre section of header 22 and that this plane is offset from and parallel to a plane, denoted P2, containing the axis X-X of internal chamber 38 of header 10 section 30, and the corresponding longitudinal axis Y-Y
of header 22. Collector 20 is arranged on the roof surface 56 so that the panel 26 is disposed closely adjacent to the surface and presents an air gap of minimum height be-tween the panel and the surface so as to minimize exposure of the panel to wind damage in use. The height of the air gap is in fact equal to the height of the lower wall portion 42 of the main section 30 of header 24. In a prac-tical embodiment, this height would be of the order of i 0.250 inches. From the headers, the panel does in fact - 20 curve downwardly into contact with the support surface 56 and is held in contact with the surface as will be described.
Accordingly, an air gap effectively exists only below the portions of the panel 26 ad~acent the headers 22 and 24.
- Another advantage which derives from applicant's form of header is that internal pressure of liquid entering panel 26 from a header tends to urge the upper and lower walls of the panel outwardly against the sealing strips 46 and 48, thereby increasing sealing efficiency between the panel and the header.
As indicated previously, header 24 also includes ~ ~ .
end fitments 32 and 34. Fitment 34 is shown in detail in Fig. 4 is an exploded position with respect to an end of the header centre section 30 and panel 26. Fitment 34 is a one-piece plastic molding and includes an inner end por-tion 60 shaped to define a recess 62 which is complementary to and dimensioned to closely receive the opposing end por-tion of header centre section 30. The depth of recess 62 is chosen to be substantially equal to the distance by which panel 26 is inset from the end of header section 30 so that the fitment in fact buts against panel 26 when in position on the end portion of section 30. The position of the fitment at this time is shown in chain dotted line at 341 in Fig. 4. Fitment 34 also includes an integral cylindrical extension 64 which projects outwardly from the inner end portion 60 and which is co-axial with the gener-ally cylindrical portion 36 of the main header section 30 when the fitment is in position on the section. Fitment 34 further includes an integral flange 66 which is disposed parallel to the bottom wall portion 42 of section 30 when the fitment is in place. Flange 66 is formed with an open-ing 68 to receive a screw for attaching the header to a ~ support surface as will be described.
; In order to ensure effective sealing of the fit-ment 34 to header section 30, a specially shaped sealing element, also of neoprene rubber, is positioned in the slot 44 of header section 30 between the outer side face of panel 26 and the end of section 30. This element is denoted 70 in Fig. 4 and is secured in place in slot 44 by adhesive.
It will of course be appreciated that the fitment 32 at the other end of the header centre section 30 is essen-iy~
tially the same as fitment 34, although of opposite hand,and that similar sealing arrangements are provided at that end oE section 30.
In this embodiment, both the header centre section 30 and the fitments 32 and 34 are made of a rigid ABS plas-tic materia]. Section 30 is a one-piece extrusion of uni-form cross-sectional shape throughout its length and is in fact manufactured in continuous lengths which may be cut to size as appropriate. The fitments 32 and 34 on the other hand are injection molded as one-piece uniis.
The fitments 32 and 34 are secured to the header centre section 30 using a çonventional MEK (methyl-ethyl-ketone) solvent. The assembly sequence is to first of all secure the panel 26 in the slot in the main header section 30 with the interposition of the neoprene sealing strips 46 and 48, and to secure the sealing element 70 (and the corresponding element at the other end of the section) into the end of the slot. Recess 62 in fitment 34 and the outer end portion of section 30 to be received in the recess are then both coated with MEK solvent and the fitment is assembled to the section as indicated by arrow 72 in Fig. 4. Fitment 32 is assembled to the opposite end of section 30 in similar fashion.
; As indicated previously, the header 22 at the upper end of panel 26 is essentially the same as header 24.
In Fig. 1, the end fitments of header 22 are denoted 74 and 76. Each fitment includes a flange similar to the flange 66 of fitment 34 (see Fig. 4) formed with an opening to receive a screw. Accordingly, four attachment points are provided for each panel in association with the end fitments _ g _ 3~3 of the respective headers. The four attachment points for the panel 26 shown in Fig. 1 are denoted respectively 78, 80, 82 and 84. The panel may be held in place by screws, nails or the like extending through the openings in the fitments at these attachment points and secured to the roof or other support surface on which the collector is positioned.
As will be explained subsequently in connection with the succeeding embodiment, in some situations, it may be de-sirable to secure to the surface the top header only in order to allow for longitudinal expansion and contraction of the panel under varying temperature conditions. However, the particular method of attachment will be determined in accordance with the discretion of the installer; not all of the available attachment points will necessarily be used in practice.
Also shown in association with panel 26 in Fig. 1 are four hold-down tabs 86. One of the tabs is shown in vertical cross-section in Fig. 5. It will be seen that the tab includes a flat, generally rectangular upper portion 88 which lies on top of the panel, and an integral collar portion 90 formed with an opening 92 to receive a screw such as that indicated at 94. Portion 88 is disposed flush with the top of collar portion 90. Tab 86 also includes à recess 96 defined between portion 88 and collar portion 90, which recess is of a height corresponding to the thick-ness of panel 26. It will be appreciated that, when the hold-down tab is secured to the roof surface 56 by screw 94, panel 26 will be held flat against the roof and will be re-strained against outward movement under the effect of wind.
Nevertheless, the panel will be free to slide longitudinally in the recess 96 in the hold-down tab as the panel expands and contracts due to temperature variations.
The solar collector is connected to the other com-ponents of the solar heating system in which it is used by way of the end fitments of the headers. For example, in Fig. 1, unit 20 is shown coupled to a second similar collector 201. The collectors are positioned side-by-side as shown and adjacent end fitments are coupled together by flexible vinyl tubes 98 and 100. A further, similar tube is shown at 102 in association with the end fitment 34 at the bottom right hand end of panel 26. Tube 102 is di-mensioned to fit closely over the tubular portion 64 of fit-ment 34 and is held in place on portion 64 by means of a gear clamp 104. A second similar clamp is shown at 106 for coupling the opposite end portion of tube 102 to another part of the system. It will be noted that portion 64 has a thickened peripheral rim 108 at its outer end over which tube 102 is fitted and behind which gear clamp 104 is tightened onto portion 64. This makes for secure, leak-free coupling of the tube to the fitment.
It will of course be appreciated that, although the two collectors 20 and 201 have been shown closely ad-jacent to one another, this is not essential. The vinyl tubes may be of any length and, since they are flexible, can accommodate virtually any relative positioning of adjacent collectors or other parts of the system. Thus, the collector will be connected to other associated equip-ment (not shown) such as pumps, valves, vacuum breakers and the like by way of similar flexible vinyl tubes. Also, it will be appreciated that the collectors need not be con-nected top heacler to top header and bottom header to bottomhe~der as shown in Fig. 1. Where the collector is used in a system in which incoming liquid to be heated is introduced into the bottom header and flows upwardly through the panel, it may be desirable to connect the top header of one col-lector to the bottom header of the adjacent collector so that the liquid flows upwardly through the panels of both collectors. Such an arrangement may be readily effected using flexible vinyl tubes of appropriate length.
Where it is necessary to blank off an end of a header, a plug or bung is secured in the outer end of the tubular portion 64 of the relevant header fitment. A
suitable plug is shown at 110 in association with fitment 76 at the upper right hand end of collector 20 in Fig. 1.
The plug is made of rubber and is force fitted into the outer end of the tubular portion of the fitment. For tem-porary installations, a force fitted plug will normally be adequate. In a permanent installation, however, the plug will be secured in place by adhesive.
Referring to Fig. 2, reference numeral 112 denotes an insert intended to be located in an end portion of one of the passages 28 in panel 26 for the purpose of restrict-ing liquid flow therethrough. One of these inserts is in fact provided in each end of each passage 28 in the panel.
Others of these inserts are visible insid~ the centre header section 30 in Fig. 2 and are indicated in dotted outline at 112 in panel 26 in Fig. 1. Each insert is of elongate rectangular shape and is of square shape in cross-section, having a longitudinally extending bore 114. The inserts are molded in an ABS plastic materiàl so that the panel re taining screws 54 can pass throu~h them if necessary. In any event, the purpose of the inserts 112 is, as indicated previously, to restrict the flow of liquid through the panel so that the liquid is in effect slowed down in its travel and remains within the panel 26 for a time sufficient to allow it to absorb a reasonable amount of solar energy.
The inserts 112 also serve the function of supporting the upper and lower walls of panel 26 during tightening of the panel retaining screws 54 to guard against accidential crushing of the panel due to overtightening of the screws.
However, it has been found in practice that the inserts are not essential for this purpose and that there is fairly minimal risk of crushing the panel if normal manu-facturing precautions are taken. Neither are the inserts essential for restricting liquid flow through the panel.
For example, if the collector is used in a closed circula-tion circuit, flow of liquid through the panel can be con-trolled by appropriately controlling the delivery rate of the purnp in the circuit. Alternatively, particularly where the unit is used in an open circuit, an adjustable restrictor valve can be provided in the discharge from an individual collector or array of collectors to provide a back pressure for controlling liquid flow. This arrangement has the ad-vantage that the valve can he adjusted to control the flow rate of the liquid in accordance with prevailing ambient temperature conditions and operating requirements.
Reference will now be made to Figs. 6 to 9 of the drawings which illustrate an alternative embodiment of the invention. Since many of the principal parts of the collector shown in these figures are very similar to parts g3~3 shown in Figs. 1 to 5, prime~ refcrence numerals have been used in Figs. 6 to 9 to indicate such parts. Thus, the collector itself is generally denoted 20' in Fig. 6 and is shown mounted on a roof surface 56'. The unit includes upper and lower headers 22' and 24' respectively and a panel 26'. Each header includes a main centre section and end fitments which, while they are basically similar to the section and fitments shown in the previous figures, incor-porate eertain modifications which will be described in eonnection with Figs. 8 and 9. However, reference will first be made to Fig. 7 in describing an alternative form of panel hold-down arrangement used in this embodiment.
Thus, the hold-down tabs 86 of the previous embodiment have been replaced by tabs denoted 116 in Fig. 6 and associated hold-down straps 118.
Referring to Fig. 7, eaeh hold-down tab ineludes a generally rectangular portion 120 and an integral eollar portion 122. A serew opening 124 is provided in the eollar portion 122 for reeeiving a serew 126 to be driven into the roof surface 56'. The tab is formed below portion 120 with a right angular reeess 128 of a height eorresponding to the thiekness of panel 26' arranged so that, when the tab is serewed to the roof surfaee, the panel is retained in reeess 128. The tab is designed to allow the panel to slide in recess 128 as it expands and eontraets due to temper-ature ehanges as deseribed in eonneetion with the previous embodiment. In faet, the partieular eolleetor shown in Figs. 7 to 9 is intended to be attaehed to the roof sur-faee by the upper header 22' only; that is, attaehment points 82' and 84'. The bottom header 24' will be free to move as the panel expands and contracts longitudinally as indicated by arrows 130. The hold-down straps and tabs merely hold the panel against the roof surface.
The straps 118 are of thin rectangular shape in cross-section and both they and the tabs 116 are made of an ABS plastic material. At its outer end, each tab is formed with a screw opening 132 which aligns with the opening 124 in the appropriate hold-down tab 116. Thus, as seen in Fig. 7, a single screw 126 is used to retain both an end of the relevant strap 118 and the tab itself. Lo-cating ribs 134 are provided on the upper surface of tab 116 and the strap fits between the ribs.
Referring now to Figs. 8 and 9, the centre section 30' of header 24' is of similar shape to the header section 3~ described in connection with the previous embodiment.
However, instead of separately attached neoprene sealing strips 46 and 48, section 30' incorporates integrally molded sealing strips 136 and 138 which define the walls of slot 44'. Section 30' is extruded in one piece complete with the sealing strips 136 and 138 by a known extrusion technique. The generally cylindrical portion 36' of sec-tion 30' and the upper and lower wall portions 40' and 42' which define slot 44' are made of a rigid vinyl material, while the sealing strips 136 and 138 are made of a soft vinyl and are compressible for sealing against panel 26'.
Further, a plurality of parallel, longitudinally extending sealing ribs 136a and 138a are molded into the sealing strips to provide for improved sealing between the strips and the panel 26'. As in the previous embodiment, the panel is retained in slot 44' by self-tapping screws 54'.
A further modification compared with the previous embodiment is that an integral sealing formation 140 is molded into the recess 62' in end fitment 34' and replaces the sealing element 70 used in the end of the centre header section (See Fig. 4). Formation 140 is positioned to fit into the end of slot 44' and seal against the relevant edge of panel 26'. As in the previous embodiment, an MEK solvent is applied both to section 30' and to end fitment 34' for securing the fitment to the section. Solvent will also be applied to formation 140 and inside the end of slot 44' at this time to ensure firm sealing of the end fitment to the section. Also, for added security of fixing, three openings 142 are provided in the inner end portion 60' of fitment 34' for receiving self-tapping screws 144 which are driven into the end portion of section 30'.
Finally, Fig. lO shows a further embodiment of the invention which may be used in association with either of the previously described embodiments to provide improved heating efficiency.
Fig. lO shows a longitudinal sectional view through a collector according to this embodiment. The headers and panel are as shown in connection with the embodiment of Figs. l to 5 and are denoted by double primed reference num-erals corresponding to the numerals used previously. For clarity of illustration, the end fitments of the headers have not been shown. The collector shown in Fig. 10 has been designed to take advantage of the so-called "greenhouse effect" and includes a sheet of transparent plastic material of the type sold under the trade mark MYLAR which is posi-tioned above and at a spacing from panel 26" so~as to pro-3~3 vide an air gap between the panel and the sheet. The MYLAR sheet is denoted 146 in Fig. 10 and is positioned with its end portions directly on top of panel 26" so that the sheet 146 is in effect trapped between the panel and the upper sealing strip 46" in the slots in the respective headers.
The panel retaining screws 54" also penetrate the MYLAR
sheet. The air gap between the MYLAR sheet 146 and panel 26" is provided by a series of protuberances or "bumps"
148 on the upper surface of panel 26". The protuberances are distributed in a 2 inch square grid pattern over the upper surface of the panel and are formed by drops of a hot melt adhesive. The side margins of sheet 146 are free so that the air gap between the panel and the sheet is open at its sides.
It will be appreciated that the presence of the MYLAR sheet will cause solar radiation incident on the panel to be trapped inside the air gap, causing a "greenhouse effect" to take place and effectively increasing the heat transferred to the liquid in the solar collector.
As indicated previously, the embodiment of Fig.
10 may also be used in association with a collector having headers and a panel of the form described with reference to Figs. 6 to 9. In that event, the hold-down straps 118 may sexve to space the MYLAR sheet 146 from the surface of the panel, thereby avoiding the need for the protuberances 148. It is further to be understood that, while a sheet of MYLAR plastic has been found to be satisfactory in practice, sheets made of other materials transparent to infrared radiation may alternatively be employed.
It should also be noted that, while the preceding 3~3 description relates to specific embodiments of the inven-tion, many modifications are possible within the broad scope of the invention. For example, the particu]ar plastic materials specifically referred to above are not to be considered as essential and may be replaced by suitable alternatives. Also, it is to be noted that, while the solar energy collectors described herein have been designed primarily for use in solar heating systems for swimming pools, there is no limitation in this and that the units may be used in other types of solar heating system. The systems themselves are conventional and it is believed unnecessary to describe them here. Nevertheless, it is to be noted that such systems may include both closed circulation cir-cuits using glycol based liquids and incorporating heat exchange means for transferring collected heat to another heat storage medium, and systems in which water circulates through the solar energy collector(s), and is used directly, e.g. in a swimming pool.
In the preceding description, the headers are described as being generally of hollow cylindrical shape.
While this particular shape may be preferred for ease of manufacture, installation and for promoting smooth flow of liquid through the header, it is to be understood that there is no limitation to this particular shape. Further, while the headers are described as comprising a centre sec-tion having separate end fitments attached thereto, there is no limitation in this regard. In another embodiment, the headers could each be molded in one piece. Where separate end fitments are provided, they could of course be attached other than by solvent welding. Suitable ad-3~3 hesives could also alternatively be used, or the end fitments could be attached by mechanical Means with the interposition of suitable gaskets.
In the embodiments described with reference to the drawings, each end fitment has a recess at its inner end which receives an end portion of the centre header section, and the panel is inset from the ends of the centre section of the header. In an alternative embodiment, the panel could extend right up to the end of the centre sec-tion and the end fitments could be molded to fit aroundthe panel.
In the drawings, the panel is shown as retained in the slot~in each header by a series of self-tapping screws. It is to be understood that this type of mechan-ical fastening of the panel to the headers is not essential.
Within the broa,d scope of the invention, the panel could be retained by adhesive in the slot in each header. The adhesive could be in the form of external beads along the joint lines between each header and the panel, or it could be applied to the co-operating surfaces of the panel and header. In this event, the slot could be formed directly in the wall of a header rather than being defined between projecting wall poriions as described. Where mechanical fastening means are employed, however, it should be noted that there is no limitation to self-tapping screws. Other alternatives are rivets and nuts and bolts.
In regard to the embodiment shown in Fig. 10 of the drawings, the plastic sheet 146 is shown trapped between the panel and the upper sealing strip 46". It is, however, to be noted that the sheet could be retained in other ways.
For example, its end portion could be disposed on top of the header wall portion 40" and held in place by the panel retaining screws 54". Also, it should be noted that the air gap between sheet 146 and panel 26" may be formed other than in the ways described. For example, the plastic sheet could be simply bowed between the two headers, provided of course it was sufficiently rigid.
Claims (15)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A solar energy collector for use in a solar heating system, the collector comprising:
first and second headers, each defining: an internal chamber disposed about a longitudinal axis and having an in-ternal wall; and a slot communicating with said chamber and extending longitudinally of the header, the header having opposed generally parallel surfaces defining opposite sides of said slot; and, an extruded plastic panel which extends between the headers and which defines a plurality of open-ended passages extending from end to end of the panel and along which liquid can flow for heating by solar radiation, opposite end portions of the panel being received in the slots in the respective headers with upper and lower sur-faces of each said portion in surface-to-surface contact with said opposed generally parallel surfaces of the rele-vant header, and the panel being sealed to the headers in liquid-tight fashion;
the slots in the headers being disposed in a com-mon plane parallel to a plane containing the axes of said chambers of the respective headers, and offset from said plane by a distance less than the maximum distance between said longitudinal axis of each header and the internal wall of said internal chamber.
first and second headers, each defining: an internal chamber disposed about a longitudinal axis and having an in-ternal wall; and a slot communicating with said chamber and extending longitudinally of the header, the header having opposed generally parallel surfaces defining opposite sides of said slot; and, an extruded plastic panel which extends between the headers and which defines a plurality of open-ended passages extending from end to end of the panel and along which liquid can flow for heating by solar radiation, opposite end portions of the panel being received in the slots in the respective headers with upper and lower sur-faces of each said portion in surface-to-surface contact with said opposed generally parallel surfaces of the rele-vant header, and the panel being sealed to the headers in liquid-tight fashion;
the slots in the headers being disposed in a com-mon plane parallel to a plane containing the axes of said chambers of the respective headers, and offset from said plane by a distance less than the maximum distance between said longitudinal axis of each header and the internal wall of said internal chamber.
2. A collector as claimed in claim 1, wherein each header includes an outer wall shaped to form a main tubular portion which defines said internal chamber, and opposed wall portions which extend longitudinally of and project out-warding from said tubular portion generally parallel to one another, and between which said slot is defined.
3. A collector as claimed in claim 1, wherein said internal chamber in each header is of generally cylindrical shape, and wherein said common plane in which the slots in the headers are disposed is generally tangential with re-spect to the internal walls of the chambers in the headers.
4. A collector as claimed in claim 1, wherein each header includes: an elongate centre section which is of a length corresponding generally to the width of said panel, and which has opposite ends and a uniform cross-sectional shape throughout its length, said section including said chamber and slot; and end fitments secured in liquid-tight fashion to said opposite ends of said centre section; each said end fitment including a cylindrical projection co-axial with said internal chamber of the header and closing said end except for said fitment, whereby the header can be coupled in said solar heating system by way of said fitment.
5. A collector as claimed in claim 4, wherein each of said end fitments includes a recess of a shape complementary to the external shape of the relevant end portion of said centre section of the associated header and in which said portion is received, and wherein said centre section and end fitments are made of materials which are bonded together by a solvent adhesive.
6. A collector as claimed in claim 4 or 5, wherein each of said end fitments includes an integral attachment flange adapted to receive means for securing the flange to a support surface, whereby the collector may be retained on said surface.
7. A solar energy collector for use in a solar heating system, the collector comprising:
first and second headers, each defining: an inter-nal chamber disposed about a longitudinal axis and having an internal wall; and a slot communicating with said chamber and extending longitudinally of the header, the header having opposed generally parallel surfaces defining opposite sides of said slot; and, an extruded plastic panel which extends between the headers and which defines a plurality of open-ended passages extending from end to end of the panel and along which liquid can flow for heating by solar radiation, opposite end portions of the panel being received in the slots in the respective headers with upper and lower sur-faces of each said portion in surface-to-surface contact with said opposed generally parallel surfaces of the rele-vant header, and the panel being sealed to the headers in liquid-tight fashion;
the slots in the headers being disposed in a com-mon plane parallel to a plane containing the axes of said chambers of the respective headers, and offset from said plane by a distance less than the maximum distance between said longitudinal axis of each header and the internal wall of said internal chamber;
wherein each header includes an outer wall shaped to form a main tubular portion which defines said internal chamber, and opposed wall portions which extend longitudinally of and project outwardly from said tubular portion generally parallel to one another, and between which said slot is defined; and, wherein the opposed generally parallel surfaces of each header are defined by resilient sealing strips dis-posed at inner faces of said opposed wall portions of the header, and wherein each header further includes mechanical fastening means extending through said wall portions, said sealing strips and said panel, and arranged to mechanically draw said wall portions inwardly to cause said sealing strips to compress against the panel and form a liquid-tight seal therewith.
first and second headers, each defining: an inter-nal chamber disposed about a longitudinal axis and having an internal wall; and a slot communicating with said chamber and extending longitudinally of the header, the header having opposed generally parallel surfaces defining opposite sides of said slot; and, an extruded plastic panel which extends between the headers and which defines a plurality of open-ended passages extending from end to end of the panel and along which liquid can flow for heating by solar radiation, opposite end portions of the panel being received in the slots in the respective headers with upper and lower sur-faces of each said portion in surface-to-surface contact with said opposed generally parallel surfaces of the rele-vant header, and the panel being sealed to the headers in liquid-tight fashion;
the slots in the headers being disposed in a com-mon plane parallel to a plane containing the axes of said chambers of the respective headers, and offset from said plane by a distance less than the maximum distance between said longitudinal axis of each header and the internal wall of said internal chamber;
wherein each header includes an outer wall shaped to form a main tubular portion which defines said internal chamber, and opposed wall portions which extend longitudinally of and project outwardly from said tubular portion generally parallel to one another, and between which said slot is defined; and, wherein the opposed generally parallel surfaces of each header are defined by resilient sealing strips dis-posed at inner faces of said opposed wall portions of the header, and wherein each header further includes mechanical fastening means extending through said wall portions, said sealing strips and said panel, and arranged to mechanically draw said wall portions inwardly to cause said sealing strips to compress against the panel and form a liquid-tight seal therewith.
8. A collector as claimed in claim 7, wherein each said header includes a one-piece extrusion comprising a first relatively rigid material forming said outer wall of the header and a second relatively soft material forming said sealing strips.
9. A collector as claimed in claim 8, wherein each of said sealing strips is shaped to define a plurality of longitudinally extending sealing ribs for sealing engage-ment with the said panel.
10. A solar energy collector for use in a solar heating system, the collector comprising:
first and second headers, each defining: an internal chamber disposed about a longitudinal axis and having an in-ternal wall; and a slot communicating with said chamber and extending longitudinally of the header, the header having opposed generally parallel surfaces defining opposite sides of said slot; and, an extruded plastic panel which extends between the headers and which defines a plurality of open-ended passages extending from end to end of the panel and along which liquid can flow for heating by solar radiation, opposite end portions of the panel being received in the slots in the respective headers with upper and lower sur-faces of each said portion in surface-to-surface contact with said opposed generally parallel surfaces of the rele-vant header, and the panel being sealed to the headers in liquid-tight fashion;
the slots in the headers being disposed in a com-mon plane parallel to a plane containing the axes of said chambers of the respective headers, and offset from said plane by a distance less than the maximum distance between said longitudinal axis of each header and the internal wall of said internal chamber;
wherein each header includes: an elongate centre section which is of a length corresponding generally to the width of said panel and which has opposite ends and a uni-form cross-sectional shape throughout its length, said section including said chamber and slot; and end fitments secured in liquid-tight fashion to said opposite ends of said centre section; each said end fitment including a cylindrical projection co-axial with said internal chamber of the header and closing said end except for said fitment, whereby the header can be coupled in said solar heating system by way of said fitment;
wherein each of said end fitments includes a recess of a shape complementary to the external shape of the rele-vant end portion of said centre section of the associated header and in which said portion is received, and wherein said centre section and end fitments are made of materials which are bonded together by a solvent adhesive; and, wherein the centre section of each header has outer end portions which project to a predetermined extent beyond said extruded plastic panel, wherein said recess in each end fitment is adapted to receive one of said pro-jecting outer end portions of the header centre section, each fitment further including an integrally formed sealing element dimensioned to project into and seal the portion of said slot in said outwardly projecting end portion of the header centre section.
first and second headers, each defining: an internal chamber disposed about a longitudinal axis and having an in-ternal wall; and a slot communicating with said chamber and extending longitudinally of the header, the header having opposed generally parallel surfaces defining opposite sides of said slot; and, an extruded plastic panel which extends between the headers and which defines a plurality of open-ended passages extending from end to end of the panel and along which liquid can flow for heating by solar radiation, opposite end portions of the panel being received in the slots in the respective headers with upper and lower sur-faces of each said portion in surface-to-surface contact with said opposed generally parallel surfaces of the rele-vant header, and the panel being sealed to the headers in liquid-tight fashion;
the slots in the headers being disposed in a com-mon plane parallel to a plane containing the axes of said chambers of the respective headers, and offset from said plane by a distance less than the maximum distance between said longitudinal axis of each header and the internal wall of said internal chamber;
wherein each header includes: an elongate centre section which is of a length corresponding generally to the width of said panel and which has opposite ends and a uni-form cross-sectional shape throughout its length, said section including said chamber and slot; and end fitments secured in liquid-tight fashion to said opposite ends of said centre section; each said end fitment including a cylindrical projection co-axial with said internal chamber of the header and closing said end except for said fitment, whereby the header can be coupled in said solar heating system by way of said fitment;
wherein each of said end fitments includes a recess of a shape complementary to the external shape of the rele-vant end portion of said centre section of the associated header and in which said portion is received, and wherein said centre section and end fitments are made of materials which are bonded together by a solvent adhesive; and, wherein the centre section of each header has outer end portions which project to a predetermined extent beyond said extruded plastic panel, wherein said recess in each end fitment is adapted to receive one of said pro-jecting outer end portions of the header centre section, each fitment further including an integrally formed sealing element dimensioned to project into and seal the portion of said slot in said outwardly projecting end portion of the header centre section.
11. A solar energy collector for use in a solar heating system, the collector comprising:
first and second headers, each defining: an internal chamber disposed about a longitudinal axis and having an in-ternal wall; and a slot communicating with said chamber and extending longitudinal1y of the header, the header having opposed generally parallel surfaces defining opposite sides of said slot; and, an extruded plastic panel which extends between the headers and which defines a plurality of open-ended passages extending from end to end of the panel and along which liquid can flow for heating by solar radiation, opposite end portions of the panel being received in the slots in the respective headers with upper and lower sur-faces of each said portion in surface-to-surface contact with said opposed generally parallel surfaces of the rele-vant header, and the panel being sealed to the headers in liquid-tight fashion;
the slots in the headers being disposed in a com-mon plane parallel to a plane containing the axes of said chambers of the respective headers, and offset from said plane by a distance less than the maximum distance between said longitudinal axis of each header and the internal wall of said internal chamber; and, in each of said open ended passages of said ex-truded plastic panel, at least one liquid flow controlinsert comprising a body of cross~sectional shape com-plementary to and adapted to fit closely in said passage, and formed with a longitudinally extending bore of prede-termined size through which liquid can flow in travelling along the relevant passage.
first and second headers, each defining: an internal chamber disposed about a longitudinal axis and having an in-ternal wall; and a slot communicating with said chamber and extending longitudinal1y of the header, the header having opposed generally parallel surfaces defining opposite sides of said slot; and, an extruded plastic panel which extends between the headers and which defines a plurality of open-ended passages extending from end to end of the panel and along which liquid can flow for heating by solar radiation, opposite end portions of the panel being received in the slots in the respective headers with upper and lower sur-faces of each said portion in surface-to-surface contact with said opposed generally parallel surfaces of the rele-vant header, and the panel being sealed to the headers in liquid-tight fashion;
the slots in the headers being disposed in a com-mon plane parallel to a plane containing the axes of said chambers of the respective headers, and offset from said plane by a distance less than the maximum distance between said longitudinal axis of each header and the internal wall of said internal chamber; and, in each of said open ended passages of said ex-truded plastic panel, at least one liquid flow controlinsert comprising a body of cross~sectional shape com-plementary to and adapted to fit closely in said passage, and formed with a longitudinally extending bore of prede-termined size through which liquid can flow in travelling along the relevant passage.
12. The com~ination of:
(a) a solar energy collector for use in a solar heating system, the collector comprising:
first and second headers, each defining: an internal chamber disposed about a longitudinal axis and having an in-ternal wall; and a slot communicating with said chamber and extending longitudinally of the header, the header having opposed generally parallel surfaces defining opposite sides of said slot; and, an extruded plastic panel which extends between the headers and which defines a plurality of open-ended passages extending from end to end of the panel and along whi.ch liquid can flow for heating by solar radiation, opposite end portions of the panel being received in the slots in the respective headers with upper and lower sur-faces of each said portion in surface-to-surface contact with said opposed generally parallel surfaces of the rele-vant header, and the panel being sealed to the headers in liquid-tight fashion;
the slots in the headers being disposed in a com-mon plane parallel to a plane containing the axes of said chambers of the respective headers, and offset from said plane by a distance less than the maximum distance between said longitudinal axis of each header and the internal wall of said internal chamber; and, (b) a plurality of hold-down tabs for use in securing the collector to a support surface, each tab including a first portion adapted to receive means for attaching the tab to said surface adjacent a side edge of said extruded plastic panel, and a second portion adapted to project outwardly over said panel and defined in part by a recess of a depth corresponding generally to the thickness of said panel and intended to receive an edge portion of said panel, said re-cess being shaped to restrain the panel against outward move-ment away from said support surface while allowing movement of the panel generally parallel to said surface as the panel expands and contracts due to temperature variations.
(a) a solar energy collector for use in a solar heating system, the collector comprising:
first and second headers, each defining: an internal chamber disposed about a longitudinal axis and having an in-ternal wall; and a slot communicating with said chamber and extending longitudinally of the header, the header having opposed generally parallel surfaces defining opposite sides of said slot; and, an extruded plastic panel which extends between the headers and which defines a plurality of open-ended passages extending from end to end of the panel and along whi.ch liquid can flow for heating by solar radiation, opposite end portions of the panel being received in the slots in the respective headers with upper and lower sur-faces of each said portion in surface-to-surface contact with said opposed generally parallel surfaces of the rele-vant header, and the panel being sealed to the headers in liquid-tight fashion;
the slots in the headers being disposed in a com-mon plane parallel to a plane containing the axes of said chambers of the respective headers, and offset from said plane by a distance less than the maximum distance between said longitudinal axis of each header and the internal wall of said internal chamber; and, (b) a plurality of hold-down tabs for use in securing the collector to a support surface, each tab including a first portion adapted to receive means for attaching the tab to said surface adjacent a side edge of said extruded plastic panel, and a second portion adapted to project outwardly over said panel and defined in part by a recess of a depth corresponding generally to the thickness of said panel and intended to receive an edge portion of said panel, said re-cess being shaped to restrain the panel against outward move-ment away from said support surface while allowing movement of the panel generally parallel to said surface as the panel expands and contracts due to temperature variations.
13. A combination as claimed in claim 12, wherein said hold-down tabs are adapted to be used in pairs at opposite sides of said extruded plastic panel, and wherein the com-bination further comprises, for use in association with each such pair of tabs, a hold-down strap intended to ex-tend transversely of the panel between said tabs and having end portions each adapted to receive said means for attaching the associated tab to said support surface.
14. A solar energy collector for use in a solar heating system, the collector comprising:
first and second headers, each defining: an internal chamber disposed about a longitudinal axis and having an in-ternal wall; and a slot communicating with said chamber and extending longitudinally of the header, the header having opposed generally parallel surfaces defining opposite sides of said slot; and, an extruded plastic panel which extends between the headers and which defines a plurality of open-ended passages extending from end to end of the panel and along which liquid can flow for heating by solar radiation, opposite end portions of the panel being received in the slots in the respective headers with upper and lower sur-faces of each said portion in surface-to-surface contact with said opposed generally parallel surfaces of the rele-vant header, and the panel being sealed to the headers in liquid-tight fashion;
the slots in the headers being disposed in a com-mon plane parallel to a plane containing the axes of said chambers of the respective headers, and offset from said plane by a distance less than the maximum distance between said longitudinal axis of each header and the internal wall of said internal chamber; and, a sheet of a plastic material disposed at a spacing from the outer surface of said extruded plastic panel so as to define an air gap between the panel and said sheet, whereby a "greenhouse effect" occurs between the panel and sheet when the collector is in use.
first and second headers, each defining: an internal chamber disposed about a longitudinal axis and having an in-ternal wall; and a slot communicating with said chamber and extending longitudinally of the header, the header having opposed generally parallel surfaces defining opposite sides of said slot; and, an extruded plastic panel which extends between the headers and which defines a plurality of open-ended passages extending from end to end of the panel and along which liquid can flow for heating by solar radiation, opposite end portions of the panel being received in the slots in the respective headers with upper and lower sur-faces of each said portion in surface-to-surface contact with said opposed generally parallel surfaces of the rele-vant header, and the panel being sealed to the headers in liquid-tight fashion;
the slots in the headers being disposed in a com-mon plane parallel to a plane containing the axes of said chambers of the respective headers, and offset from said plane by a distance less than the maximum distance between said longitudinal axis of each header and the internal wall of said internal chamber; and, a sheet of a plastic material disposed at a spacing from the outer surface of said extruded plastic panel so as to define an air gap between the panel and said sheet, whereby a "greenhouse effect" occurs between the panel and sheet when the collector is in use.
15. A collector as claimed in claim 14, further com-prising means on the upper surface of said extruded plastic panel for mechanically spacing said transparent plastic sheet above the surface of the panel for defining said air gap, said means comprising a plurality of upwardly protuberant elements distributed over the upper surface of said panel and arranged to hold the sheet clear of said upper surface.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA293,284A CA1110938A (en) | 1977-12-16 | 1977-12-16 | Solar energy collector |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA293,284A CA1110938A (en) | 1977-12-16 | 1977-12-16 | Solar energy collector |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1110938A true CA1110938A (en) | 1981-10-20 |
Family
ID=4110305
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA293,284A Expired CA1110938A (en) | 1977-12-16 | 1977-12-16 | Solar energy collector |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1110938A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2610394A1 (en) * | 1987-02-02 | 1988-08-05 | Kaysersberg Sa | Plastic heat-exchanger comprising a panel and two manifolds |
| US20120145142A1 (en) * | 2004-11-01 | 2012-06-14 | Reuben Clark | Solar Panel and Method for Heating Pools and Spas |
| WO2015044882A1 (en) * | 2013-09-24 | 2015-04-02 | Pontificia Universidad Católica De Chile | Device for stiffening and sealing a solar collector |
-
1977
- 1977-12-16 CA CA293,284A patent/CA1110938A/en not_active Expired
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2610394A1 (en) * | 1987-02-02 | 1988-08-05 | Kaysersberg Sa | Plastic heat-exchanger comprising a panel and two manifolds |
| US20120145142A1 (en) * | 2004-11-01 | 2012-06-14 | Reuben Clark | Solar Panel and Method for Heating Pools and Spas |
| US9133971B2 (en) * | 2004-11-01 | 2015-09-15 | Reuben Clark | Solar panel and method for heating pools and spas |
| WO2015044882A1 (en) * | 2013-09-24 | 2015-04-02 | Pontificia Universidad Católica De Chile | Device for stiffening and sealing a solar collector |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |