Solar energy collector system

A solar energy collector system including at least one heat exchange panel posessing a system of internal tubular passageways defining opposed headers connected by connecting portions of said passageways extending therebetween, said passageways including entry and exit portions extending from opposing ends of said headers to provide ingress and egress openings for a heat exchange medium. The panels include at least one internal, second passageway adjacent and in juxtaposition to said internal tubular passageways but spaced therefrom and independent therefrom.

BACKGROUND OF THE INVENTION 
The present invention relates to a solar energy collector system including 
at least one metal panel having a system of internal tubular passageways 
disposed between spaced apart portions of the thickness of the panel. A 
heat exchange medium is circulated through said passageways wherein said 
panels utilize solar energy for elevating the temperature of the heat 
exchange medium. 
It is well known that the radiation of the sun can be collected as a source 
of energy for heating or cooling or for direct conversion to electricity. 
Heating and cooling based on solar energy depend upon collection of rays 
of solar energy in a fluid heat transfer system. The heated fluid is 
pumped or allowed to flow to a place of utilization for the thermal energy 
it has acquired, with a temperature sensing device employed in association 
with the panel for controlling the circulation of fluid therethrough. 
In certain areas of the world, solar energy is the most abundant form of 
available energy if it can be harnessed economically. Even in more 
developed areas of the world, the economic harnessing of solar energy 
would provide an attractive alternative to the use of fossil fuels for 
energy generation particularly in this era of increased fuel costs. 
One of the problems attending the development of an efficient system for 
the conversion of solar energy resides with the specific structure and 
design of the solar energy absorbing device or solar collector. This solar 
energy collector generally comprises a rectangular plate-like structure 
possessing channels or passageways therein for the circulation of the 
energy absorbing fluid medium. Conventionally, these channels comprise a 
pair of opposed expanded passageways, known as headers, which are placed 
at opposite ends of the panel, and are connected by a plurality of tubular 
passageways which are often in parallel relation with respect to each 
other. In addition, it is necessary to provide a temperature sensing 
device in association with the plate-like structure in order to accurately 
and efficiently determine the temperature thereof and control the 
circulation of said heat exchange medium throughout the system. A 
plurality of these temperature sensing devices are often employed 
depending upon the particular system in order to provide very accurate 
temperature control and a highly efficient system. In addition, it is 
often desirable to provide other means in association with the panel or 
plate-like structure, such as a desiccant in order to absorb moisture from 
the closed system wherein the plate-like structure resides. That is, the 
plate-like structure is generally enclosed by a glass plate and it is 
desirable to absorb moisture from between the panel and glass plate. 
A represenatative panel structure is shown in our co-pending U.S. patent 
application Ser. No. 573,953, filed May 2, 1975, and now abandoned, the 
disclosure of which is incorporated herein by reference. In accordance 
with said co-pending application, it was determined that improved flow 
characteristics are obtainable in such a rectangular plate-like structure 
by a modification of the disposition of the headers wherein the headers 
define an angle of at least 91.degree. with respect to the direction of 
flow of the heat exchange medium. 
The aforementioned temperature sensing devices or other means are normally 
associated with the panel or plate-like structure by adhering same to the 
outside surface of the plate-like structure in a secondary operation. This 
represents an inefficient method which does not obtain maximum efficiency 
in the solar collector system. Also, it represents a costly secondary 
operation which may not result in accurate temperature determination. 
Accordingly, it is a principal object of the present invention to provide 
an improved solar energy collector system. 
It is a still further object of the present invention to provide an 
improved solar energy collector system including at least one heat 
exchange panel possessing a system of internal tubular passageways wherein 
said panel is suitable for integral internal disposition of a second 
passageway system which may be used in containing a control means, such as 
a temperature sensing device. 
Further objects and advantages of the present invention will appear 
hereinbelow. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, the foregoing objects and 
advantages may be readily achieved and an improved solar energy collector 
system provided. The improved solar energy collector system of the present 
invention includes at least one heat exchange panel possessing a system of 
internal tubular passageways defining opposed headers connected by 
connecting portions of said passageways extending therebetween, said 
passageways including entry and exit portions extending from opposed ends 
of said headers to provide ingress and egrees openings for said heat 
exchange medium. Preferably, a common distribution manifold is connected 
to each of said entry portions and a common collection manifold is 
connected to each of said exit portions. The improvement of the present 
invention comprises the provision of at least one internal second 
passageway in said heat exchange panel adjacent and in juxtaposition to 
said internal tubular passageways but spaced therefrom and independent 
therefrom. In the preferred embodiment two of said second passageways are 
provided, one of which is adjacent the entry portion and one of which is 
adjacent the exit portion. Generally, a control means is provided within 
said second passageway, such as a temperature sensing device operatively 
connected to means for controlling the flow of said heat exchange medium 
within the panel. The temperature sensing device may be connected to a 
control box which energizes a pump at a preselected temperature, for 
example 100.degree. F., to move the heat exchange medium through the 
system. The second passageway is provided with a crimped inlet opening 
terminating at an edge of said panel so that the control means may be 
firmly held within the second passageway. Alternatively, the second 
passageway may be used to hold other suitable means, such as a desiccant 
charge to absorb moisture between the panel and a glass cover which is 
generally provided over the panel. In this instance, a plurality of holes 
is provided in the second passageway. 
It can be readily seen that the solar energy collector system of the 
present invention achieves numerous and significant advantages. The second 
passageway provides an appropriate receptacle at any desired location 
integral with the heat exchange panel. The second passageway can be of 
virtually any appropriate size for the desired function. If a temperature 
sensing device is employed, said device can be located very close to the 
outlet or inlet tubes or both without interfering with the fluid flow 
within the system. This can provide a very accurate temperature sensing 
means within the panel itself, which is more accurate than a temperature 
sensing device attached to the outside of the panel. Also, the fact that 
the second passageway can be crimped shut provides a very secure assembly 
making it virtually impossible to dislodge the temperature sensing device 
while permitting opening for maintenance if desired. Also, these 
advantages are obtained inexpensively without the necessity for a costly 
secondary attachment operation. Alternatively, other means may be 
conveniently provided within the second passageway, such as a desiccant 
bag with appropriate holes drilled in the metal adjacent the second 
passageway. As a still further alternative, the control means within the 
second passageway may comprise a low wattage heater for use under freezing 
conditions.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
The panels of the present invention are utilized in a solar energy 
collector system as shown in FIG. 1 wherein a plurality of panels of the 
present invention 10 are mounted on a roof 11 of building 12 with conduits 
13 and 14 connected in any convenient fashion to the balance of the solar 
energy collector system which may be in the building. Thus, for example, 
cold water may pass into conduit 13 from the building 12 or may from a 
structure exterior thereto by means of conventional pump 15 or the like. 
The water flows along common manifold 13a and is distributed into panels 
10. The water flows through panels 10, is heated by means of solar energy, 
is collected in common manifold 14a and flows into conduit 14 for storage 
in storage chamber 16 or utilization in a heat exchange system inside the 
building in a known manner. The exact construction of the pump, storage 
and utilization means are well known and are only shown schematically 
herein. Naturally, if desired the water flow may be reversed with the cold 
water entering via conduit 14 and collected via conduit 13. Alternatively, 
the solar collector system of the present invention may be used or placed 
in any suitable environment, such as on the ground with suitable fasteners 
to prevent displacement by wind or gravity. It has been found that the 
solar energy collector system of the present invention may be readily used 
for residential heating purposes, such as providing hot water in a 
residential environment. For example, three panels in a solar energy 
collector system of the present invention having dimensions of 8'.times.4' 
would efficiently supply an average household of four with hot water for 
home use. Alternatively, the solar panels of the present invention may be 
conveniently used for heating water for swimming pools or for preheating 
water for domestic gas or oil fired domestic hot water heaters. The fluid 
is preferably retained in a closed system with the water in the system 
being heated in the solar unit and delivered to an insulated cistern or 
storage chamber such as is shown schematically by reference numeral 16 in 
FIG. 1 so that the heated fluid may be stored up during sunshine for use 
on cool, cloudy days or at night when the heating of the fluid in the 
panel will not be of sufficient degree to provide the desired heat at the 
point of use. 
A temperature sensing device, the exact disposition of which will be 
discussed hereinbelow, is provided in the solar energy collector system of 
the present invention to turn on pump 15 whenever the temperature reaches 
a predetermined reading. The pump will then pump the water through the 
system as generally outlined above. FIG. 1 shows a plurality of 
temperature sensing devices 17 connected to control box 18 via manifolds 
19a and line 19. 
As indicated hereinabove, the solar energy collector system of the present 
invention includes at least one heat exchange panel possessing a system of 
internal tubular passageways defining opposed headers connected by 
connecting portions of said passageways extending therebetween, said 
passageways including entry and exit portions extending from opposed ends 
of said headers to provide ingress and egress openings for a heat exchange 
medium. As will be seen hereinbelow, the panels utilized in the system of 
the present invention have a particularly preferred design for optimum 
efficiency. The metal panel or plate used in the system of the present 
invention is desirably fabricated by the ROLL-BOND.RTM. process as shown 
in U.S. Pat. No. 2,690,002. FIG. 2 illustrates a single sheet of metal 20, 
such as aluminum or copper or alloys thereof having applied to a clean 
surface 21 thereof a weld inhibiting material 22 corresponding to the 
ultimate desired passageway system and to the desired second passageway 
system. FIG. 3 shows the sheet 20 having superimposed thereon a second 
sheet 23 with the patterns of weld inhibiting material 22 sandwiched 
between the units. The units 20 and 23 are tacked together as by support 
welds 24 to prevent relative movement between the sheets as they are 
subsequently welded together as shown in FIG. 4 by passing through a pair 
of mill rolls 25 to form welded blank 26. It is normally necessary that 
the sheets 20 and 23 be heated prior to passing through the mill rolls to 
assure that they weld to each other in keeping with techniques well known 
in the rolling art. The resultant blank 26 is characterized by the sheets 
20 and 23 being welded together except at the areas of the weld inhibiting 
material 22. Blank 26 with the unjoined inner portion corresponding to the 
patterns of weld inhibiting material 22 may then be softened in any 
appropriate manner as by annealing, and thereafter the blank may be cold 
rolled to provide a more even thickness and again annealed. The portions 
of the panel adjacent the weld inhibiting material 22 are then inflated by 
the introduction of fluid distending pressure, such as air or water, in a 
manner well known in the art to form a system of internal tubular 
passageways 30 corresponding to the passageway pattern of weld inhibiting 
material shown in FIG. 5. The passageways 30 extend internally within 
panel 10 and are disposed between spaced apart portions of the thickness 
of the panel. Thus, panel 10 comprises a hollow sheet metal panel or plate 
having a system of fluid passageways 30 for a heat exchange medium 
extending internally therein. If the passageways are inflated by the 
introduction of fluid distending pressure between flat die platens, the 
resultant passageways have a flat topped configuration 31 as shown in FIG. 
6. If on the other hand, passageways 30 are formed without the presence of 
superimposed platens the resultant passageway configuration has a 
semicircular shape 32 as shown in FIG. 7. In addition to the foregoing, 
panel 10 also includes at least one second passageway 50 disposed between 
spaced apart portions of the thickness of the panel. The second 
passageways 50 are inflated by the introduction of fluid distending 
pressure in the same manner as the system of fluid passageways 30. If a 
plurality of second passageways 50 are provided, they may be 
simultaneously expanded by manifolding the inflation apparatus so that 
fluid distending pressure is simultaneously introduced into the plurality 
of said second passageways. As can be seen in FIG. 5, the internal second 
passageways are preferably located adjacent and in juxtaposition to the 
internal tubular passageways 30 but spaced therefrom and independent 
therefrom. In accordance with the embodiment shown in FIG. 5, two of said 
second passageways are provided, one of which is adjacent entry portion 35 
and the other of which is adjacent exit portion 36. 
As shown in FIG. 5, the passageways 30 include opposed headers 33 connected 
by connecting portions 34 of said passageways of substantially uniform 
cross section extending substantially longitudinally in panel 10 between 
headers 33 and interconnecting same, with the opposed headers 33 extending 
in a direction substantially transverse to said longitudinal passageways. 
Preferably, opposed headers 33 are connected by a plurality of spaced, 
parallel individual connecting portions 34 of said passageways extending 
between the headers. 
In accordance with the present invention, the passageways include entry 
portion 35 and exit portion 36 extending from the opposite ends of headers 
33 to opposed edges 40 and 41 of panel 10 to provide ingress and egress 
openings for the heat exchange medium. Headers 33 possess outer edges or 
boundary sides 42 and 43, respectively, defining the perimeter thereof 
adjacent entry portion 35 and exit portion 36, respectively, extending 
therefrom. In a preferred embodiment of the present invention the headers 
33 define an angle of at least 91.degree. with respect to the direction of 
fluid flow, indicated by phantom line 37 in FIG. 5. Thus, the external 
angle is defined by line 37 and adjacent boundary side 40 of header 33 and 
may generally range from 92.degree. to 100.degree., preferably from 
921/2.degree. to 971/2.degree.. If desired, the connecting portions 34 may 
also define angles of at least 1.degree. with respect to the direction of 
fluid flow (not shown). In all of the above instances where angles have 
been defined, it is to be understood that said angles are measured as they 
lie in the plane of the panel and comprise the convergence of the boundary 
side and connecting portion respectively with the longitudinal dimension 
of the panel represented by the line extended in phantom. The foregoing is 
more completely described in co-pending U.S. patent application Ser. No. 
632,502 now U.S. Pat. No. 4,109,711 issued Aug. 29, 1978, by the inventors 
herein, the disclosure of which is incorporated herein by reference. 
The provision of an angled header, and if desired angled connecting 
portions, enables uniform fluid distribution within panel 10. Thus, one 
provides a means to fully drain fluid from the unit and to provide a drain 
for collected gases thereby preventing air locks. Proper drainage 
mitigates the possibility of internal solution freezing in the unit with 
possible subsequent expansion and tube wall fracture. In addition, proper 
fluid drainage eliminates the possibility of sediment collecting in the 
unit which would create an environment conductive to corrosion. Also, a 
more efficient solar energy collector system is provided. 
An additional feature of the panels utilized in the system of the present 
invention is to provide headers 33 that include bonded portions 38 of 
metal which is welded together to provide improved header strength, 
improved fluid flow control and directionality and interruption in the 
flow of the heat exchange medium. This can be readily provided in 
accordance with the present invention by simply not including weld 
preventive material where one desires to provide the bonded portions 38. 
In the preferred embodiment, the entry and exit portions 35 and 36 
intersect each respective header at the center thereof and are in a line 
with each other. If desired, however, the entry and exit portions may 
intersect each respective header at opposite ends thereof as shown by 
entry and exit portions 35b and 36b in FIG. 9. Naturally, also, the entry 
and exit portions may if desired extend in the same direction as the 
header as shown in FIG. 9 in phantom as 35b' and 36b'. 
The symmetrical design of the panels of the present invention makes the 
panels easier to handle so that either end may be the upper portion. The 
angled header feature promotes drainage in both ends of the panel. FIGS. 8 
and 9 show variation in the panel design of the present invention. 
Naturally, numerous other variations can readily be devised. FIG. 8 shows 
a panel 10a wherein the portions of headers 33a defining an angle 37a with 
respect to entry and exit portions 35a and 36a, respectively, are 
scalloped as shown at 44. This header configuration enables efficient 
channeling of fluid flow throughout the system. As shown in FIG. 8, 
opposed headers 33a are connected by a plurality of individual, spaced 
parallel connecting portions 34a of said passageways extending between the 
headers. A plurality of bonded portions 38a are included in headers 33a. A 
plurality of said second passageways 50a are provided around the periphery 
of panel 10a for inclusion of a plurality of control means, if desired. 
FIG. 9 shows an alternative embodiment wherein panel 10b includes entry 
and exit portions 35b and 36b intersecting each respective header 33b at 
opposite ends thereof and defining angle 37b at opposite ends thereof. Two 
of said second passageways 50b are provided at opposite ends of panel 10b, 
one of which is adjacent entry portion 35b and the other of which is 
adjacent exit portion 36b. 
FIGS. 10 and 11 show details of the second passageway 50a. In accordance 
with FIG. 11, the second passageway is provided with opening 51 
terminating at an edge of the panel. FIG. 10 shows the opening crimped 
shut at 52 to securely hold the control means therein. In accordance with 
FIG. 10, a plurality of holes 53 are drilled in the metal adjacent the 
second passageway 50a for including a desiccant charge in the second 
passageway, for example, a molecular sieve or silica gel. The holes allow 
for proper venting. This feature is particularly desirable in geographical 
areas where the venting of the solar collector box would cause condensate 
to form on the interior thereof. In accordance with FIG. 11, a temperature 
sensor 54 is provided within the second passageway with lead 55 extending 
therefrom. As indicated hereinabove, the temperature sensor is operatively 
connected to a means for controlling the flow of the heat exchange medium 
within the panels. Alternatively, or in addition, one may provide a low 
wattage heater within the second passageway for use under freezing 
conditions. This is particularly advantageous as it effectively avoids 
freeze-up problems. 
An additional advantage of the present invention is that the secondary 
passages may be used to increase the structural strength of the unit by 
positioning them along the longitudinal and/or transverse panel edges. 
This invention may be embodied in other forms or carried out in other ways 
without departing from the spirit or essential characteristics thereof. 
The present embodiment is therefore to be considered as in all respects 
illustrative and not restrictive, the scope of the invention being 
indicated by the appended claims, and all changes which come within the 
meaning and range of equivalency are intended to be embraced therein.