CA1127485A - Solar energy collector system having balanced heat-exchange fluid flow - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A coupling used between headers of adjacent collectors in an array of solar collectors of the liquid heat-exchange type to balance the flow of heat exchange fluid through the absorber of each collector. The coupling is formed with an internal baffle in which an orifice of predetermined area is defined dependent on its position in the array.
The coupling may also be used to vent entrapped air from the headers and to drain liquid from them.

Description

This invelltion rela-tes to solar ener~y collectors of the li~uid heat-excllange type.
Collectors of the liquid heat-exchange type generally comprise a housing having an absorber located therein. A
plurality of conduits are connected between upper and lower headers and in intimate heat-exchange relationship with the absorber. The headers of each collector may be connected to common manifolds or other conduits, or directly to the headers of adjacent collectors.
l~llen several of the collectors in an array are connected in a parallel flow arrangement for liquid in the conduits, a flow condition develops which creates non-uniform output temperatures in the collector array. The temperature of the liquid from the collectors in the center of the array is generally substantially higher than the temperature of the liquid from collectors at the ends of the array. This indi-cates that less liquid is flowing through the center collec-tors than through the end collectors, and therefore less total heat is transferred to the liquid in the center collectors, not~ithstanding the higher temperatures. The non-uniform fluid flow is due to the fact that both headers are of constant dimension from one end of the collector array to the other.
This causes a condition of relatively low flow resistance through the headers near the inlet and outlet ends of the array and relatively high flow resistance through the headers at the center of the array. The greater the resistance to fluid flow the lower the flow rate. The lower the flow rate of a fluid through a collector the higher the outlet temperature of the collector.
The non-uniform fluid flow could be counteracted by providing appropriately tapered head~rs or manifolds. How-ever, this is not a practical solution from the standpoint of manufacturing expense.
Another solution is to place balanciny valves between the connections of the headers of each collector, or between the respective manifolds and the collectors.
Such valves are, however, expensive and require large spa-cing between adjacent collectors, reducing the area of collector coverage where the area availabl~ to collect sun-light is limited. Furthermore, the individual valves eachrequire proper adjustment, which can take a considerable amount of time and is often not done properly by installers.
The present invention can provide a new and im-proved means for regulating the flow of liquid through manifolds or headers of a collector array, facilitating a shortened coupling between the headers and manifolds or the headers of adjacent collectors. The invention can fur-ther provide means for draining liquids from the system and/or bleeding air from the system, depending on the posi-tion of the means in the input headers or the output headers.
According to the invention, there is provided amethod to facilitate the balanced flow of liquid through an array of solar collectors of the heat exchange type, each collector having inlet and outlet headers with conduits ex-tending therebetween, comprising connecting said inlet headers into a liquid input line so as to establish connec-tion between each of said headers and a liquid input by means of coupling members each connected to a connection on an inlet header and another part of the input line so as to complete a liquid path through a passageway in the coup-ling member between the liquid input and said inlet headers, connecting said outlet headers into a liquid outlet line establishing a connection between said headers and a liquid ~3~

outlet by means of coupling members each connected to a connection on an outlet header and another part of the out-let line so as to complete a liquid path through a passage-way in the coupliny member between the liquid outlet and said outlet headers, at least some of said coupling members having integral baffles forming an orifice adapted to re-strict the flow through its passageway, and selecting the sizes of the orifices in said coupling members so that they change progressively from end to end of the array to balance the flow of liquid through the collectors of the array.
The invention also extends to solar collector arrays so constructed and to the coupling members used therein. The coupling members may further include a normal-ly closed bleeder vent which can be used either to bleed air or drain liquid - --3a-1.8~

from tile system depending on whether it is directed upwardly or down~ardly.
In a second embodiment, the member is resilient and includes an accordion fold to permit the headers to expand or contract. In this embodiment the bleed vent is optional.
An object of this invention is to provide a new and improved apparatus for regulating the flow of liquid in an array of parallel liquid heat-exchange solar energy collectors.
Another object of the invention is to provide a new and improved header or manifold coupling member for collectors of the type described which functions to regulate the flow of liquid to the respective collectors and facilitates re-ducing the spacing between collectors in the array.
A further object of the invention is to provide a new and improved coupling member of the type described which also permits bleeding and draining of the system.
The features of the invention which are believed to be novel are particularly pointed out and distinctly claimed in the concluding portion of this specification. The inven-tiOll, however, both as to its organization and operation together with further objects and advantages thereo~ may best be appreciated by reference to the following detailed description taken in conjunction with the drawings, wherein:
FIG. 1 is a plan view of a six collector array with the covers of three collectors partially cut away;
FIG. 2 is a view partially in section seen in the plane of lines 2-2 of Fig. l;
FIG. 3 is a sectional view seen in the plane o~ lines 3-3 of Fig. l;
FIG. 4 is an end view of a coupling member for coupling 3,5 the headers of adjacent collectors together;
FIG. 5 is a sectional view seen in the plane of lines 5-5 of Fig. 4;
FIGS. 6, 7 and 8 are views of the connector of Fig. 4 showing progressively lar~er areas of the internal baffle thereof removed;
FIG. 9 is a schematic diagram of the collector array of Fig. 1 showing the headers and the coupling member therebetween;
FIG. 10 is a side sectional view of a second embodiment of the invention; and FIG. 11 is a schematic diagram of a collector array between manifolds and having coupling members between the manifolds and the collectors.
An array 10 of collectors includes a plurality of individual collectors. As exemplified in Fig. 1, array 10 includes six collectors 11-16. Each collector comprises a housing 17 including side walls 18 and 19, end walls 20 and 21, a base 22 and trans-parent cover 23. Within the housing is situated an absorber 24 resting on insulation 25. Extending inside the collectors along the lower and upper ends of the absorber are lower and upper headers 26 and 27. A plurality of conduits 28 extend beween headers 26 and 27 in intimate heat-exchange relationship with absorber 24. The headers 26 and 27 are exemplified as being con-nected to headers of adjacent collectors to form inlet and outlet lines. Each header may alternatively be connected to manifolds (see Fig. 11) to form inlet and outlet lines. The ends of the headers in the extreme upstream and downstream collectors are terminated by caps 29 through 32. The lower header of the upstream collector 11 includes a liquid inlet 33 and the downstream i'9 ~

collector 16 upper header 27 includes an outlet 34. The ou-tlet and inlet are similar in construction. The outlet is exemplified in Fig. 3, and hereinafter described.
As exemplified in Fig. 2, each collec~or includes a housing shown as being of the type disclosed in Canadian Patent No.
1,093,408 issued to the present applicant on January 13, 1981.
Side wall 19 includes an inwardly directed ledge 35 ~or sup-porting transparent cover member 23. Tlle cover member is clamped between support ledge 35 and a cap 36, which is afixed to side wall 19 by means of scraws extending into the trough formed by vertical members 37 and 38 and horizontal member 39. A flashing reglet 40 provides a seat for flashing (not shown) extending between adjacent collectors.
Header 27 extends through an aperture 41 in side wall 19.
An adapter member 42 is seated in aperture 41 and carries therein an annulus of sealing member 43 which surrounds header 27 to insulate it from contact with the housing frame and prevent cooler ambient air from leaking into the collector.
Header 27 is provided with end connections 44 swaged to a sli~htly enlarged diameter. The enlarged ends receive a coupling member 45 described more fully hereinafter. Headers 26 are also provided with enlarged end connections to receive a coupling member 45.
An arrangement of the outlet 34 of the collector array is exemplified in Fig. 3. Header 27 terminates short of end wall 19 and is received within one arm of a tee-shaped fitting 46. The other arm of tee 46 received a cap 47. The lower leg of tee 46 received a fitting 48 adapted to receive a conduit (not shown) to a heat storage or heat utilization device, depending on the purpose of the heating system. The fitting 48 extends through base 22, the base including an adapter 49 extending into the collector. ~n annular sealing member 50 insulates tee 46 and fitting 48 from the base 22.
As exemplified in Figs. 4 an~ 5, coupling member 45 includes a hollow cylindrical body 51 derining a passageway 51a and havillg an internal baffle 52 extending thereacross.
Varying areas of baffle 52 are removed to define orifices having sizes depending on the location of a particular coup-ling member 45 in the array. A bleed vent 53 extends from the body, covered by cap 54 threaded thereon. The bleed vent 53 preferably extends from the center of the cylindrical body.
A collar 55 extends around the center of the body to provide ~ ~,,6~ co7~ccf~'~,7~i uniform separation for the opposing ~K~ of the headers con-nected thereto, and to facilitate soldering the ends to member 45.
Figs. 6, 7 and 8 exemplify three coupling members 45a, 45b and 45c in which differing areas of baffle 52 have been removed.
Fig. 6 exemplifies a coupling member 45a in which a small area of baffle 52 has been removed to provide a small orifice 20 52a. Coupling member 45b has a larger orifice 52b in its baffle and coupling member 45c, shown in Fig. 8, has a still larger orifice 52c in its baffle 52. It is apparent that flow through coupling member 45a will be restricted to a greater extent than through coupling member 45b, and flow through coupling member 45c will be restricted the least.
The array 10, as schematically exemplified in Fig. 9, has coupling member 45c coupling headers 26 of collectors 11 and 12, coupling member 45b coupling headers 26 of collectors 13 and 14, and coupling member 45a coupling headers 26 of collec-tors 15 and 16. The inlet 33 is situated in headers 26 of 3~
upstream collector 11. The heat-exchange conduits 28 of the individual eollectors are not shown in Fig. 9.
Coupling member 45a serves to eouple ~he headers 27 of eollee-tors 11 and 12, coupling member 45b couples headers 27 of collec-tors 13 and 14 and coupling member 45c couples headers 27 of collectors 15 and 16. Outlet 34 is situated in header 27 of down-stream eollector 16.
The couplin~ between the other header ends may be a coupling disclosed in our Canadian Patent Application Serial No. 321,191, filed February 9, 1977, arranged to eompensate for header expansion and contraetion.
In operation, the liquid entering from inlet 33 into headers 26 eneounters increased resistanee to flow due to the eoupling 45c in headers 26 and eoupling 45a in headers 27, thus insuring a given flow in the eonduits 28 of colleetor 11.
Couplings 45b in headers 26 present further resistance to direet flow of the liquid in both headers and thus provides a given flow in the eonduits 28 of eolleetors 12 and 13. Coupling 45b in headers 27 has a larger orifiee than eoupling 45a and pre-sents less resistanee to total liquid flow in header 27. There-fore, the liquid in the headers of eolleetors 11, 12 and 13 may flow at substantially the same rate.
Coupling 45a in headers 26 and eoupling 45e in headers 27 further inerease the resistanee to flow in both headers, whieh insures substantially uniform flow through the eonduits 28 of eolleetor 16.
Coupling 45c in headers 27 has the largest orifiee 52c of the eouplings in headers 27 to offer the least resistance to the liquid entering headers 27 of eollectors 11-15.
The arrangement of the eoupling members 45a-45e in the array of ~ig. 9 presents a system analogous to headers 26 having a decreasing cross-sectional area from collector 11 to collector 16, and headers 27 having an increasing cross-sectional area from collector 11 to collector 16. In this manner the pressure of the liquid at each conduit 28 at its junction with a header 26 is substantially constant resulting in substantially uniform liquid flow through each conduit 28.
This results in lligher overall efficiency of the collector array.
Bleed vent 53 can serve as either an air vent or as a drain, depending on whether the vent is directed upwardly or E do~nwardly. In array 10, exemplified in Fig. 9, the vents of the coupling members between ~eaders 27 are shown directed up~ardly and thus serve as air vents. The vents in coupling members in lower headers 26 are directed downwardly, and can serve as drains.
Baffle 52 shown in Figs. ~ and S is exemplified as being across the center of the body 51. Baffle 52 may be si-tuated any~here along passageway 51a. If baffle 52 is not directly opposite bleed vent 53, opening 56 need not initially be pro-vided in baffle 52.
Bleed vent 53 may be omitted from the coupling member.
In such event, opening 56 may similarly be omitted.
Baffle 52 may take any convenient shape. The baffle may be angled with respect to fluid flow; it may have, for example, a triangular cross-section, a smooth curve approximating a venturi. A venturi may reduce fluid turbulence in the system.
The sizes and relative sizes of openings 52a, 52b and 52c in the internal baffles 52 exemplified in Figs. 6, 7 and 8 are 3n by ~ay of example only. The particular size of the openings is selected to balance fluid flow to each of the collectors 11 thrQugh 16 in tile array 10. If a longer array is required in an installation having more collectors, more coupling mem-bers 45 may be providecl between subsequen-t pairs of collec-tors, and the orifices 52 in all of the coupling members must be adjusted accordingly.
Coupling member 45 may be formed from a rigid material sucll as brass, or alternatively may be formed from a resilient milterial such as silicone.
Fig. 10 exemplifies a coupling member 57 formed from a resilient material such as silicone. Member 57 includes a body 58 which is substantially cylindrical except for a cir-cumferential accordion fold 59 which will accommodate expan-sion and contraction of the headers.
Body 58 defines a passageway 60 having baffle 61 extend-ing thereacross. Member 57 is used in the same manner as member 45, with varying amounts of baffle 61 being removed depending on the location in the collector array, and the ends e, ~ cO~ c~ ,7~s~
of body 58 receiving the ~*~ of the headers therein.
Fig. 11 schematically illustrates an array 70 of six collectors 71 through 76, each having an inlet header 77 and an outlet header 78. A plurality of heat-exchange conduits 79 extend between headers 77 and 78 in each collector. The collectors are connected between an inlet manifold 80 and an outlet manifold 81.
The inlet headers of collectors 71-76 are connected to inlet manifold 8n, the headers of collectors 72 through 76 being connected through couplings 45e through 45a, respectively. The upstream collector 71 is connected directly to inlet manifold 80. Couplings 45d and 45e are similar to tj couplillg members 45a through 45c with successively larger portions of baffle 52 being removed in couplings 45d and 45e.
Similarly, tile outlet headers o-f collectors 71-76 are connected -to outlet manifold 81, the headers of collectors 71-75 being connected through coupling members 45a through 45e, respectively.
In the absence of coupling members 45a through 45e, with the varying size baffles, the flow of fluid through the col-lectors would not be balanced and the collectors towards the center would be warmer.
In operation, the effect of the couplings 45a-45e between manifold 8b and headers 77 is to present a substantially uniform fluid pressure in the manifold 77 of all of the collectors, and the couplings 45a-45e between headers 78 and mallifold 81 act to balance the total flow of liquid through each of the collectors. This arrangement effectively acts as an inlet manifold of decreasing tapering cross-section from upstream toward the downstream and an outlet manifold of increasing flaring cross-section from the upstream toward the downstream.
Alternately, the couplings may be installed in manifolds 80 and 81 to achieve a similar flow pattern.
Various arrangements of the balancing inserts may be utilized. They need not be placed above one another as shown in Fig. 9. For example, in an eight collector array9 three inserts 45a, 45b and 45c may be used in the return header between the first four collectors, and three inserts 45c, 45b, and 45a between the last four collectors in the supply headers.
This arrangement provides an advantage in that the total pressure drop across the entire array is less than for arrays witll the inserts above one another in the return and supply lleader connections as described in connection with Fig. 9.
The lower total pressure drop is desirable in that it reduces the pumping energy required to move a given amount of liquid through the collector.
It may thus be seen that the objects of the invention set forth as well as ~hose made apparent from the foregoing description are efficiently attained. While preferred embodilllents of the invent-on have been set forth for purposes of disclosure, modification to the disclosed embodiments of the invention as well as other embodiments thereof may occur to those skilled in the art. Accordingly, the appended claims are intended to cover all embodiments of the invention and modifications to the disclosed embodiments which do not depart from the spirit and scope of the invention.

Claims (26)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. In an array of solar collectors of the liquid heat-exchange type, each having inlet and outlet headers with conduits extending therebetween, the headers having connections by which they are connected into input and out-put lines; a coupling member adapted to connect between a connection of a header of one collector and a connection to another part of the line of which it forms part to facili-tate the balanced flow of liquid through the conduits of the collectors, said coupling member having two ends, one end coupled to each connection, said coupling member having a body defining a passageway therethrough between said ends, and an integral baffle extending across said passageway and defining an orifice of predetermined area adapted to re-strict the flow of liquid therethrough to balance the flow of liquid passing through the collectors.

2. A coupling member as defined in Claim 1, where-in said coupling member further includes a circumferential collar to space apart the connections to which it is adapted to couple.

3. A coupling member as defined in Claim 1, fur-ther comprising a normally-closed bleed vent extending from said body.

4. A coupling member as defined in Claim 1, where-in said body is resilient.

5. A coupling member as defined in Claim 4, where-in said body includes a circumferential accordion fold.

6. A solar collector array of the liquid heat-exchange type each having inlet headers and outlet headers, the inlet headers being interconnected and the outlet hea-ders being interconnected and a plurality of coupling members each coupling a connection to a header of one col-lector to a connection to a header of another collector to facilitate the balanced flow of liquid through the collec-tors, said coupling members having two ends, each end coup-led to one of the connections, means defining a passageway through said body between said ends, and an integral baffle extending across said passageway defining an orifice adap-ted to predeterminedly restrict liquid to flow therethrough and dimensioned to balance the flow of liquid passing through the collectors.

7. An array as defined in Claim 6, wherein the coupling members are associated with the headers of every other pair of collectors in the array.

8. An array as defined in Claim 6, wherein each of the coupling members includes a normally-closed bleed vent, each of the vents of the coupling members associated with the lower headers being inclined downwardly to facili-tate draining the array and each of the vents of the coup-ling members associated with the upper headers being in-clined upwardly to facilitate venting the array.

9. A solar collector array of the liquid heat-exchange type, each collector having headers connected to manifolds with heat-exchange conduits extending between said headers, and coupling members each adapted to couple a connection to a header to a connection to its associated manifold to facilitate the balanced flow of liquid through the collectors, said coupling members having one end con-nected to one connection and the other end connected to the other connection, means defining a passageway through said coupling members between said ends, and a baffle ex-tending across said passageway through said coupling defining an orifice dimensioned to restrict liquid flow therethrough to balance the flow of liquid passing through the individual collectors.

10. An array as defined in Claim 9, wherein the inlet header of the upstream-most collector, and the outlet header of the downstream-most collector, are both connected directly to the associated manifold.

11. A coupling member adapted to couple a con-nection to one end of a header of a solar energy collector of the liquid heat-exchange type to a connection to the remainder of a liquid inlet or outlet line of which it forms part, said coupling member having a body defining a passage-way between ends adapted to couple to said connections, and an integral baffle extending across said passageway whereby the size of a flow-restricting orifice through said coup-ling member may be predetermined by removing a predetermined portion of said baffle, said body further including a cir-cumferential collar to space apart the connections to which it is adapted to couple.

12. A coupling member as defined in Claim 11, further comprising a normally-closed bleed vent extending from said body.

13. A coupling member as defined in Claim 11, wherein said body is resilient and includes a circumferen-tial accordion fold.

14. A system for regulating fluid flow through a plurality of conduits extending in parallel from a line of headers comprising a plurality of coupling members coup-ling connections on said headers, each of said coupling members defining a passage therethrough and having an in-tegral baffle transverse of the passage, a portion of the baffle of each coupling member being removed in progressive area to define flow restricting orifices of progressively varying area along a length of said line of headers.

15. A method to facilitate the balanced flow of liquid through an array of solar collectors of the liquid heat-exchange type, comprising:
providing an array of solar collectors of the liquid heat-exchange type, each having spaced apart headers with conduits extending therebetween;
positioning said collectors so that headers of adjacent collectors may be connected to form an input hea-der line and an output header line, said input header line having a liquid input at one end of the array, said output header line having an output return at the other end of said array;
providing a plurality of coupling members, each member having two ends adapted to connect between connec-tions to the headers of adjacent collectors, said members defining a passageway between said ends to permit liquid to flow therethrough, an integral baffle extending across the passageway of said members and defining an orifice there-through;
forming a sequence of said coupling members in each header line, the orifices of the coupling member in the input header line being of decreasing area from the liquid input and of increasing area in the output header line towards said output return; and connecting the adjacent headers, at least two of said connections being provided by connecting each of the ends of a coupling member to connections to corresponding adjacent headers, whereby upon application of fluid to the input header line, the flow of fluid therealong will be increasingly restricted and directed through said conduits of each collector with substantially balanced flow in said conduits for the entire array.

16. The method of Claim 15, wherein at least one of said coupling members further includes an annular collar to space apart the ends of connections to adjacent headers.

17. The method of Claim 15, wherein at least one of said coupling members further comprises a normally-closed bleed vent extending from said body.

18. The method of Claim 15, wherein at least one of said coupling members is resilient.

19. The method of Claim 18, wherein said resili-ent coupling member further comprises a circumferential accordion fold.

20. The method of Claim 15, wherein each of said collectors have inlet and outlet headers, said inlet hea-ders being interconnected by said coupling members and said outlet headers being interconnected by said coupling members.

21. The method of Claim 20, further comprising connecting coupling members between connections to adjacent headers of every other connection of headers in the array.

22. The method of Claim 21, further comprising:
positioning each of the collectors to have an up-per header and a lower header, each of said coupling members further including a normally-closed bleed vent;
connecting coupling members to adjacent lower headers so that said vent is inclined downwardly to facilitate draining of the array; and connecting coupling members to adjacent upper headers so that said vents are inclined upwardly to faci-litate venting of the array.

23. A method to facilitate the balanced flow of liquid through an array of solar collectors of the liquid heat-exchange type, comprising:
providing an array of solar collectors of the liquid heat-exchange type, each collector having spaced apart headers and heat-exchange conduits extending between said headers;
providing an inlet manifold and an outlet mani-fold each adapted to be connected to corresponding headers of adjacent collectors;
positioning said collectors and manifolds so that connections may be established between said collector hea-ders and said inlet manifold and outlet manifold respec-tively, said inlet manifold having a liquid inlet at one end of the array and said outlet manifold having a liquid outlet at the other end of said array;
providing a plurality of coupling members, having two ends adapted to connect between a connection on a collector headers and a connection on a manifold, an inte-qral baffle extending across the passageway of said members and defining an orifice therethrough, the area of the ori-fice being determined by removal of a portion of said baffle;
forming a sequence of said coupling members es-tablishing connections between a manifold and connections on the associated headers of successive collectors in the array, the orifices of the coupling members being predeter-mined in size to restrict flow between a manifold and said headers to balance the flow of liquid through each of said collectors.

24. The method of Claim 23, wherein at least one of said coupling members further comprises a normally-closed bleed vent extending from said member.

25. The method of Claim 23, wherein at least one of said coupling members is resilient and includes a cir-cumferential accordion fold.

26. A method to facilitate the balanced flow of liquid through an array of solar collectors of the heat-exchange type, each collector having inlet and outlet headers with conduits extending therebetween, comprising connecting said inlet headers into a liquid input line so as to establish connection between each of said headers and a liquid input by means of coupling members each connec-ted to a connection on an inlet header and another part of the input line so as to complete a liquid path through a pas-sageway in the coupling member between the liquid input and said inlet header, connecting said outlet headers into a liquid outlet line establishing a connection between said headers and a liquid outlet by means of coupling members each connected to a connection on an outlet header and another part of the outlet line so as to complete a liquid path through a pas-sageway in the coupling member between the liquid outlet and said outlet headers, at least some of said coupling members having integral baffles forming an orifice adapted to restrict the flow through its passageway, and selecting the sizes of the orifices in said coupling members so that they change progressively from end to end of the array to balance the flow of liquid through the collectors of the array.