Note: Descriptions are shown in the official language in which they were submitted.
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~. This invention relates to solar energy and
j:: . more particularly to improved structure for collecting
solar energy.
The capability o~ utilizi~g the energy which
S comes from the sun.has received widespread attention in ~.
rece~t months, particularly since the now well-known
n: "energy crisis". The basic prir.ciples of solar energy
collection are known and there have been proposed many 1.;
` : ~:. different arrangements for accomplishing this basic
purpose. ~7hile the need to utilize solar energy clearly
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- exists and the basic principles by which solar energy
can be utilized are known, the actual utilization is
minimal. The most common explanation is that while known
solar energy collectors work and have the capability to
efficiently operate in a very economical and highly
favorable ecological manner, the initial costs are said
to be prohibitive. The still existing need is for an
effective collector which can be produced on a large
scale basis at greatly reduced costs compared with those
o~ known constructions.
- An object of the present invention is to
provide a solar energy collector which will meet the
above noted needs. In accordance with the principles
of the present invention this objective is obtained by
providing a solar energy collector which i5 of laminated
sheet structure, the various layers of the laminated
sheet structure being ~abricated by molding or extruding
plastic material and effecting a simple assemblage thereof
which is effective in operation.
Another object of the present invention is to
provide a solar powered water or air heater which can be
readily and easily recycled with minimum labor and energy
consumption for purposes of materials conservation.
` Another object of the present invention is to -
_`~ 25 provide a solar powered water or air heater which can be
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shipped, stored,,and placed in seryLce with min~mum packaging
and handling expense'xe~ultin~ in lo~'~nst~lled costs.
Another obj'ect o~ the'present ~n~ention concerns
design fea`tures ahle'to regulate'the'internal system temper-
ature thus preventing materials degradation in cas-e of fluid
circulaton failure.
A further object of the present invention is to
` provide a solar powered air or water heater which collects
'. more radiation than it emits by control of internal surface
orientations.
Yet another object of this invention is to provide ;,
a solar powered air or water heater which efficiently collects
nearly all incident wave lengths and emits only a small
amount of radiation by control of internal surface properties. '
t In accordance with one broad aspect, the invention
relates to a radiant energy heat exchanger comprising:
a panel structure having sides of substantial area
', bounded by a thin periphery including opposed peripheral end
'' portions, one of said sides being operable to face in a
direction to receive radiant energy with the other side facing
in opposed relation to said opera~le side, said panel structure
including
a base defining the other side of said panel structure
and having a multiplicity of transversely spaced barrier walls
extending longitudinally between the end portions of said
panel structure, each of said barrier walls including outer
portions disposed outwardly in a direction toward the operable
side of said panel structure and extending longitudinally
between the end portions thereof, adjacent pairs of barrier
walls defining in said base a multiplicity of side-by-side
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channels extending lon~itudinally between the'end portions of
said p~neI structure,'
an inner' sheet':~brm wall section sea'lin~l~ connected
with each pai~ of ad~acent ~arrier walls at positions along
the outer porti`ons thereof and extending transversely across
the associated pair of adjacent ~arrier walls and longitudinally
between the end portions of said panel structure so as to
enclose the associated channel and thereby provide a plurality
of inner fluid containing channel spaces extending longitu-
dinally between the end portions of said panel structure,
an outer sheet form wall section sealingly connected
with each pair of adjacent barrier walls at positions along
the outer portions thereof and extending transversely across r
the associated pair of adjacent barrier walls outwardly of the
associated inner wall and section longitudinally between the
end portions of said panel structure, the exterior surfaces
of said outer wall sections defining coextensive areas of
the operable side of said panel structure,
an intermediate sheet form wall section sealingly
connected with each pair of adjacent barrier walls at
positions along the outer portions thereof and extending
across the associated pair of adjacent barrier walls between
the associated inner and outer wall sections and longitudinally
between the end portions of said panel structure so as to
define a multiplicity of outer and intermediate fluid con-
taining spaces in outwardly disposed relation with respect to
said multiplicity of inner fluid containing channel spaces,
said sheet form wall sections being constructed to
~acilitate the passage of radiant energy inwardly there-
through so that a ~low of fluid directed through said inner
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fluid containing channel spaces from a position adjacent one
end portion of said paneI structure to a position adjacent
the other end portl'on o~ said paneL structure will result ~n
radiant energy being received by the fluid flow only after
such radiant ener~y passes inwardly through said sheet form
wall secti~ons and said outer fluid containing spaces,
said base being constructed to retard the passage
of radiant energy therethrough.
TXese and other objects of the present invention
will become more apparent during the course of the following :~ -
detailed description and appended claims.
The invention may best be understood with reference
to the accompanying drawings, wherein an illustrative
embodiment is shown.
In the drawings:
Figure 1 is a front elevational view of one form
of a solar energy collector embodying the principles of the
present invention;
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, Figure 2 lS an enlarged, fragmentary sectional
view taken along the line 2-2 of Figure l;
Figure 3 is a fragmentary sectional view taken
along the,line 3-3 of Figure l;
Figure 4 is an enlarged fragmentary sectional
,, view taken along the line 4-4 of Fi~ure l;
Flgure 5 is a fragmentary front elevational view
, of another form of solar energy collector embodying the
principles of the present invention;
Figure 6 is an enlarged fragmentary sectional
- - view taken along the line 6-6 of Fi~ure 5;
~, Figure 7 is a view simila~r to Figure 6 showing
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the manner in which the collector i~ rolled up for
transportation and storage;
Figure 8 is a view simila,r to Figure 6 illustrating
the component parts of the collecto,F shown in Figure 5
i~ in a position which they may assume during assembly; and
Flgure 9 is a fragmentary sectional view illus-
trating one configuration for manifl?lding the collector
shown in Figure S.
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--~ Referring now more particularly to Figures 1-4
of the drawings, there is shown therein a panel form of a
solar energy collector, generally indicated at 10, embody-
ing the principles of the present invention. The solar
energy cpllector panel L0 is formed essentially of
laminated sheet structure from relatively inexpensive
moldable plastic materials. As best shown in Figure 2,
the laminated sheet structure of the collector 10 has a
relatively rigid panel form providing an operative side
of substantial area to be mounted in a position to receive
the solar energy and an opposite coextensive side which
may be regarded as a mounting side, both sides being
bounded by a relatively thin periphery.
In the preferred embodiment shown the mounting
side of the collector panel 10 is provided by a base
layer 12, which may be regarded as a relatively thick sheet
formation, preferably made from a suitable foamed plastic
materlal, such as urethane, styrene or urea formaldehyde.
The base layer 12 is thus characterized by lightness of
weight and rigidity. Moreover, by utilizing injection
molding techniques to form the base layer 12 of foamed
plastic material, the base layer 12 may be conveniently
formed with configurations embodying the principles of the
~ present invention. As best shown, one side 14 of the base
G 25 layer 12 is planar and this side defines the mounting side
f'~~ of the collector panel 10. The opposite side of the base
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layer 12 is formed with a multiplicity of cooperating pairs of
angularly related inclined surfaces 1~, each pair of surfaces 16
diverging outwardly with respect to one another in a direction
away from the planar side 14 to cooperatively define an
elongated channel shape.
While it is within the contemplation of the present
invention that the surfaces 16 of the foamed plastic of the base
layer 12 provide both the heat retention function of the opaque
walls and the fluid impervious function of fluid passages, it is
preferred to adhere a barrier film 18 to these surfaces to pro-
vide both functions. Desirably, the film 18 is initially vacuum
formed and then held against the upper surface form of the mold
as the plastic foam is added during the molding of the base layer
12. The ilm 18 is opaque and may be of any desired color. Suit-
able plastic materials for the film 18 include polycarbonates,acrylics, polyvinyl chlorides, polyvinyl fluoride, rubber com-
pounds, etc. It will also be understood that the barrier film 18
may provide only the fluid impervious function in which case a
sprayed-on coating or integral skin may provide the opaque
function.
The sheet formation of the collector panel is
completed by the provisions of three transparent plastic
sheets 20, 22 and 24 mounted over the base layer 12 and barrier
\ \ film 18.
The lower film sheet 20 is bonded on the upper
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ridge portions of the walls provided by barrier film 18
in the configuration shown in Figure 2 to extend across
each channel and define with the remaining unbonded
portions of the barrier wall a closed fluid conveying
channel 26.
Film 20 is bonded on the upper ridges of barrier
layer 18 in any suitable-manner, such as by heat welding,
solvent welding, or adhesive bonding techniques. A pre-
ferred manner is to utilize the heat available from
channel molds which hold film 18 to soften film 20 suffi-
_ ciently to produce welding to barrier film 18 when the
surfaces are joined under mold pressure. Sheets 22 and
24 are bonded along strips or lines at the ridge peaks in
a similar manner. The lower surface of the sheet 22 extend-
ing between each pair of adjacent peaks defines with the
coextensive upper surface of the sheet 20 a lower insulating
air space 28. Likewise, the upper surface portions of the
sheet 22 define upper insulating air spaces 30 with the
coextensive lower surface portions of the sheet 24. Sheet
22 is intentionally formed to the bridged surface shown, as
is film sheet 20 for purposes of allowing for uneven
expansion and contraction of the various members in response
to climateological and application conditions. Upper
sheet 24 is somewhat thicker than films 18, 20 and 22, and
_ 25 is selected to offer protection from projectiles, hail, and
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~ , other hazards, in addition to confining insulating air
. ~ within space 30.
The collector panel 10 is preferably made to
be a self-contained unit by manifolding the ends of the
channels. 26 and the air spaces 28 and 30. This may be`
accomplished in any desired fashion, however a preferred
mode, as illustrated in the drawings, embodies the
provision of a tapered manifold trough surface at each
end of the base layer 12 which is covered with the
barrier film 18 to form a ta2ered manifold trough 32
. communicating with the associated end o, the channels 26.
Communication with each manifold trough 32
exteriorly of the panel 10 is provided by any suitable
means, such as a plastic pipe section 34 which is either
mounted within cavities molded in the base layer or
provided in situ at the time the base layer is molded.
Any portion of the film 18 covering the adjacent end of
each pipe 34 during assembly is simply cut away.
Each manifold trough 32 is preferably enclosed
and sealed about the associated pipe 34 by means of the
adjacent portions of the three sheets 20, 22 and 24. As
best shown in Figure 4, the portions~ofthe sheets 20, 22
and 24 which overlie each manifold trough 32 are spaced
-~ apart from each other and remain unsecured. The end
_ 25 portions of the three sheets 20, 22 and 24 which overlie
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, the end wall of the base layer 12 defining the associated
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; ~ manifold trough 32 are secured together in sealed relation.
and to the upper surface of the base layer. In this way,
the portions of the sheets 20 and 22 overlying each manifold
_ough 32 define a manifold space for the adjacent ends of
. ~ the lower air~spaces 28, while the portions of the sheets
22 and 24 overlying each manifold trough define a manifold
space for the adjacent ends of the upper air spaces 30.
Prevention against over-heating due to insufficient
heat removal rates is an important consideration in instances
where failure of the fl~id circulation system would allow
~ - system temperatures to exceed material or fabrication
limits. Most applications involve placins the collector
panels 10 on somewhat inclined surfaces. This facilitates
gatherins maximum amounts of solar enersy, draining the
system for cleaning and freeze protection, and for draining
surface moisture following snow or rain showers. Pressure
and temperature control for the air spaces 28 and 30 can he
provided by the use o conventional valving illustrated
: schematically in Figure 1 of the drawings at 36 and 38. In
the schematic arrangement shown, an openins (not shown) is
formed in the portion o the intermediate sheet 22 overlying
the manifold trough and underlying the valve 36 so as to
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communicate the manifold spaces of both air spaces 28
and 30. It will be understood that the manifolds for the
_ 25 air spaces 28 and 30 may be maintained separate and provided
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with separate valves, if desired. Buoyant forces result-
ing from heating air masses between the transparent films
result in mass flow of the heated air out valve 36 as
illustrated in Figure 1 when such valve is open. Control
S of valve,36 can be provided by constructing the valve of
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materials which have high thermal,expansion coefficients
resulting in automatic opening at predetermined temperatures.
Another type of automatic control is to operate valve 36
~- by solenoids and provide normally - c~losed - power - on
functions with valve opening to occur in case of power
_ failure or any other failure resulting in deficient fluid
flow. The specific construction of valves operated by
'~ material expansion-contraction forces or solenoids is
well-known, and need not be further discussed in this dis-
closure. Providing valves 38 at lower extremities to
allow cool air to replace hot air passing through valve 36
thus enables maintenance of the system within design temper-
ature. In areas where airborne dust prevails, filter strips
over the vent valve inlet areas may be required to prevent
build-up of dust on internal surfaces.
It will be understood that collector panels 10 in
the unitized form described above are arranged to be
installed with procedures normally utilized in installing
`'- other types of wall or roofing panels with appropriate con-
- 25 nections to the pipes 34 of the panels. Normally, the
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~- - panels lO will be regarded as add-on panels rather than
panels which also serve as the exterior protective paneling
as well. ~evertheless, such dual functioning is contemplated
although other embodiments of the present invention herein-
after described are preferred in such dual functioning
situations~ Factory assembled panels including layers 12,
18, 20 and 22 may be utilized as a combination collector
and membrane roof surface with a sheet 24 applied as a con-
tinuous glazing for exclusion of water. Characteristic
lG materials selection for the sheets or 'ilms 20, 22 and 24
_ are the same as those of film 18, namely, polycarbonates,
acrylic, polyv1nyl chloride, polyvinyl fluoride, and
rubber compounds.
Referring now more particularly to Figures 5-9,
there is shown therein a second embodiment of the present
invention which facilitates manufacture and application of
; relatively large collection areas. A rigid characteristic
such as provided by the panel lO is not utilized but instead
a rolled mat form, generally indicated at 40, which
facilitates shi?ping and storage much like large carpets
or sheet-like floor coverings. Production of 100' wide
"continuous" lengths for purposes of reducing manufacturing
and application costs is offered for large heat collection
requirements. The thickness of the embodiment as shown in
__ 25 the enlarged section of Figure 6 is typically less than 3/4".
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r ``` In its preferred form the rolled mat collector
40 is made up of two plastic extrusions 42 and 44 suitably
bonded together in a manner hereinafter more fully
explained. ~he extrusion 42 constitutes the base layer
of the collector 40 similar to the base layer 12 and
~ilm 18 previously described of the panel 10. Extrusion
42 is formed of opaque plastic material, whereas extrusion
44 is formed of transparent plastic material. and is com-
parable to the transparent sheets 20, 22 and 24 of the
panel 10.
As best shown in Figures 6-8, opaque extrusion
42 has a cross-sectional configuration which provides
cooperating pairs of walls 46 defining a ~-shape which
diverge outwardly in a manner similar to the comparable
walls of the film 18. The free edge of each leg of the
V-shaped walls is integrally joined with the free edge.
o an adjacent leg of an adjacent pair of walls. Moreover,
the lower apexes of adjacent V-shaped walls are integrally
interconnected with inwardly foldable wall sections 48.
Extrusion 44 has a cross-sectional configuration
which defines a series of side-by-side lower and upper
: air spaces 50 and 52 similar to the air spaces 28 and 3
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previously described, each of which is provided by lower,
intermediate and upper thin wall sections 54, 56 and 58
integrally joined with each other along opposite edges
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--~ and with adjacent opposite edges of adjacent wall sections
54, 56, and ~8.
Assembly of the upper transparent extrusion 44
on the lower opaque extrusion 42 is by heat ~onding in
the configuration shown wherein the wall sections 54
extend across the wall sections 46 to form enclosed fluid
channels 60 (Figure 6), similar to the channels 26
previously described. As best shown in Figure 5, the
- bonaing is interrupted periodically along the length of
the extrusions, as indicated by the phantom lines 62, for
_ a purpose hereinafter to be more fully explained.
For shippins and storage a length of assembled
extrusions 42 and 44, as for example 144 inches, is cut
from the continuously formed and assembled extrusions.
Such length may contain 6 to 8 unbonded sections. The
length is then rolled up like a rug with the assembly
assuming the curvature as shown in Figure 7. It will be
noted that the wall sections 48 fold inwardly to permit
the rolling-up action. In application, the collector 40
is typically oriented with the water passageways or
channels 60 extending along the slope of the surface that
the collector i5 attached to. Unrolling the system while
simultaneously stretching wall sections 48 rlat over the
surface to which a suitable adhesive has been sprayed
~_ 25 produces a rigidized large area collector system. To
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~ ~! facilitate connection of the collector to inlet and outlet
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conduits, the collector is cut along the center of the
unbonded sections 62 which upper and lower e~trusions 42
and 44 produce two flaps of bonding over per orated inlet
S and outlqt tubing 64 as is clearly illustrated in
Figure 9. For widths less than the manufactured-width,
the collector 40 may be cut-along any water channel line
and sealed at each end. Thus rectangular areas of nearly
any width and length dimensions can be accommodated with
the rolled mat collector 40.
In operation, both embodiments employ the multiple
layers of plastic material to reduce heat loss fron! the water
within the channels. The upper transparent sheets or thin
wall sections produce a layer of stagnant air between it
-15 and the inner sheets or wall sections, thus preventing wind
cooling of the inner collector materials. The middle sheet
or wall section reaches a temperature more or less equal to
the water channel material and thus blocks radiation from
the water channel to the cool portions of the sky around
the sun. The air spaces next to the water channels insulate
with the middle film promoting equalization of water
channel and middle film temperatures. In applications
where surface winds are minimized by architectural features
or landscaping, the middle sheet 22 or wall sections 56
__ 25 may be omitted without serious loss in collection efficiency.
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The extended surface represen,ed by the wetted
area of the lower channel deLining walls of the embodimer.ts
provides an opa~ue absorber for radia~ion passins through
the transparen, fil~s and water wi.hin the channels.
Lisht rays not totally absorbed ana converted into heat
are rerlected toward opposite walls thereby considerably
increasing (compared to conventional fla, plate scnemes)
conversion of available insolen/ce in'o heat energy. ~adia-
tion from the opaque wetLed surfaces are at infrared wave-
lengths which are efCiciently absorbed by the water in the
channels. Hea'L loss through radiation is li.~i,ed by the
relatively small transparent area perper.dicular to a coole.
sink. Thus, the system operates as a radiation trap havir.s
a collection area ef ectively larger ~han its loss area
by the ratio oL the wetted opaque area to ~he wetted
transparent area. Essentially the same a~alysis ap~lies
to the opaque portion with respec' to transparent ~ortion
where the medium being heated wi.hin the channel is air
instead 0c waLer.
Relative di~ensions including ,he inc uded anc,le
between the wetted walls defining the channels, the l~r.gtn
ol wetted wall compared to dry walls, and film ~hicknesses
can be emperically optimized for minimum total costs.
Resulting configurations which utilize polycarbonate ma.er,al
selections included angles between 30 a~d 60 with 1/16"
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minimum air spacings between the transparent films. Increas-
ing the minimum air spacing and~or decreasing the included
angle increases the water temperatures achievable. However,
overheating the plastic film may result during fluid circula-tion ,
failures unless outside sprinklers, shade, or venting of the
stagnant air layers are provided to prevent operation beyond
design temperatures. Utilization of glass or other high
temperature material selections for the transparent members
would increase the acceptable design temperatures but long
useful lives have been achieved for water temperatures of 170F
in embodiments using polycarbonate transparent films. Thus,
external sprinkling to prevent operation beyond design limits
and for purposes of rinsing the system to maintain dust free
transparent surfaces has proved preferable to more expensive
material selections.
Improvement of low sun angle collection compared to
flat glazed flat plate collectors is also offered by thermo-
forming upper sheets or thin wall sections. Optimum curvatures
and lens profiles differ with the angle of inclincation to the
sun and with the chosen included angle. It is intended
that local manufacturers of the invention provide optimized
curvature of upper sheet 24 or upper wall sections 58 for
local conditions of low angle collection. In relatively
cool ~orthern ambients where relatively high humidities pre-
vail, the included angle may be 30 and sections of sheet 24
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or wall sections 58 may be c~rved on a 1" radius. In hot
dry climates the included angle may be 60 and the sheet
24 or wall sections 58 may be curved on a 2" radius.
; ~ , It thus will be seen that~the objects of this
invention have been fully and effectively accomplished. It
will be realized, however, that the foregoing preferred
specific embodiment has been shown and described for the
purpose of illustrating the functional and structural prin-
ciples of this invention and is subject to change without
departure .rom such principles. Therefore, this invention
~ includes all modifications encompassed within the spirit and
scope of the following claims.
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