U.S. patent application number 13/227606 was filed with the patent office on 2012-03-15 for solar thermal panels.
Invention is credited to Brendan J. O'Grady.
Application Number | 20120060830 13/227606 |
Document ID | / |
Family ID | 45805446 |
Filed Date | 2012-03-15 |
United States Patent
Application |
20120060830 |
Kind Code |
A1 |
O'Grady; Brendan J. |
March 15, 2012 |
SOLAR THERMAL PANELS
Abstract
Systems and methods for employing solar thermal energy for
heating are disclosed. In some embodiments, a system is disclosed,
in which a thermal-fluid-filled solar-thermal panel that has been
sealed to prevent leakage of the thermal fluid. In other
embodiments, a method of sealing a solar thermal panel is
disclosed. In one preferred embodiment, the solar thermal panel is
sealed by applying heat to one edge of the solar thermal panel,
thereby melting the edge and forming a seal.
Inventors: |
O'Grady; Brendan J.; (Ada,
MI) |
Family ID: |
45805446 |
Appl. No.: |
13/227606 |
Filed: |
September 8, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61381545 |
Sep 10, 2010 |
|
|
|
Current U.S.
Class: |
126/660 ;
29/890.033 |
Current CPC
Class: |
F24S 10/501 20180501;
F24S 10/502 20180501; Y10T 29/49355 20150115; F24S 10/55 20180501;
Y02B 10/20 20130101; Y02E 10/44 20130101 |
Class at
Publication: |
126/660 ;
29/890.033 |
International
Class: |
F24J 2/22 20060101
F24J002/22; B21D 53/02 20060101 B21D053/02 |
Claims
1. A method of manufacturing a solar thermal panel, comprising the
steps of: extruding a polymer panel comprising layers, the polymer
panel further comprising an open edge; and melting the open edge to
form a sealed edge.
2. The method of claim 1, wherein the melting step comprises the
steps of: pressing the top of the polymer panel with a heated die,
thereby causing the layers to melt together to form a seal.
3. The method of claim 1, wherein the melting step comprises the
steps of: heating the open edge with a radiative heat source.
4. The method of claim 1, wherein the melting step comprises the
steps of: heating the open edge with a convective heat source.
5. The method of claim 1, wherein the melting step comprises the
steps of: heating the open edge with a conductive heat source.
6. A solar thermal panel manufactured using the method of claim
1.
7. A solar thermal panel comprising: a bottom channel for carrying
thermal fluid, the bottom channel having a bottom-channel seal to
prevent leakage of the thermal fluid from the bottom channel; a
first hole located near a first edge of the bottom channel, the
first hole for receiving the thermal fluid from an external source;
a second hole located near a second edge the bottom channel, the
second hole for expelling the thermal fluid from the solar thermal
panel; and a top channel located above the bottom channel, the top
channel having a top-channel seal.
8. The panel of claim 7, further comprising: an inlet attached to
the first hole; and an outlet attached to the second hole.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. provisional
patent application Ser. No. 61/381,545, having the title "Solar
Thermal System," filed 2010 Sep. 10, which is incorporated herein
by reference in its entirety.
FIELD OF THE DISCLOSURE
[0002] The present disclosure relates generally to solar thermal
panels and, more particularly, to systems and methods for
manufacturing and sealing solar thermal panels.
BACKGROUND
[0003] Collecting the sun's energy with solar panels for use in
home heating and water heating is a concept that has previously
been explored and implemented. However, most currently-existing
designs focus on efficiency, rather than cost. As a result, solar
thermal panels have not gained widespread use. Thus, a heretofore
unaddressed need exists in the industry to address the
aforementioned deficiencies and inadequacies.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] Many aspects of the disclosure can be better understood with
reference to the following drawings. The components in the drawings
are not necessarily to scale, emphasis instead being placed upon
clearly illustrating the principles of the present disclosure.
Moreover, in the drawings, like reference numerals designate
corresponding parts throughout the several views.
[0005] FIG. 1 is a diagram that shows one embodiment of a solar
thermal system.
[0006] FIG. 2 is a front profile view of a solar thermal panel.
[0007] FIG. 3 is a side profile view of a solar thermal panel.
[0008] FIG. 4 is a side profile view of a solar thermal panel being
sealed.
[0009] FIG. 5 is a perspective view of a solar thermal panel.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0010] Reference is now made in detail to the description of the
embodiments as illustrated in the drawings. While several
embodiments are described in connection with these drawings, there
is no intent to limit the disclosure to the embodiment or
embodiments disclosed herein. On the contrary, the intent is to
cover all alternatives, modifications, and equivalents.
[0011] Brief Overview
[0012] The present disclosure teaches various systems and methods
relating to solar thermal panels and solar thermal systems. Unlike
conventional solar thermal panels, various embodiments of the
inventive solar thermal panels are cost-effective to manufacture,
thereby allowing for mass production of the solar thermal panels.
In some embodiments, a method of sealing a solar thermal panel is
disclosed. In one preferred embodiment, the solar thermal panel is
sealed by applying heat and pressure to one edge of the solar
thermal panel, thereby melting the edge and forming a seal. In
other embodiments, a system is disclosed, in which a
thermal-fluid-filled solar-thermal panel that has been sealed by
applying heat to its edge to prevent leakage of the thermal
fluid.
[0013] Previous Failed Attempts and Eventual Success
[0014] Before describing the various embodiments of the invention,
it is worthwhile to understand how the inventive solar thermal
panels and systems were developed, along with the corresponding
processes for manufacturing these panels and systems. Although the
inventive solar thermal panel and its method of manufacture may
appear simple, numerous failed attempts prior to the eventual
success in building the disclosed working models demonstrate the
non-trivial nature of the inventive solar thermal panels, systems,
and methods. Consequently, one having ordinary skill in the art
will appreciate the difficulties associated with manufacturing the
disclosed solar thermal panels and systems.
[0015] A particularly challenging problem related to properly
sealing the panel to prevent leakage of the thermal fluid from the
solar thermal panel. As one can imagine, in order to maximize the
heat capacity within the solar thermal system, much (if not all) of
the thermal fluid should be maintained within the solar thermal
panel. Unfortunately, if there are leaks in the solar thermal
panel, then the thermal fluid can escape, taking with it any heat
that is stored in the thermal fluid.
[0016] Sealing the solar thermal panel posed a particularly
difficult problem that was not easily overcome. For example, U.S.
Pat. Nos. 4,114,597 and 4,178,914 describe headers for unitary
solar collectors. These headers are separate components that are
attached to the outside of the unitary solar collector. Attempting
to attach separate headers to the outside of the solar thermal
panel posed problems because the interface between the headers and
the unitary solar collector, if not perfectly sealed, created
points-of-failure where the thermal fluid escaped from the system.
All attempts to externally seal the solar thermal panel with this
separate and distinct component (such as a header or a pipe)
resulted in incomplete seals, which consequently resulted in
leakage of thermal fluid from the system. This occurred despite
numerous attempts with many different types of sealants and
adhesives. Thus, while it may appear trivial to externally seal the
solar thermal panel, the reality of employing a separate component
to achieve a leak-resistant seal proved to be unworkable.
[0017] Moving away from a separate header that attached to the
outside of the solar thermal panel, attempts were also made to seal
the solar thermal panel by removing a portion of the inner channel
to create a cavity, and then friction-fitting a pipe in the
resulting cavity and sealing the interface between the pipe and the
wall of the solar thermal panel. Although intuition suggests that
both friction and a commercial sealant, when used in conjunction,
would provide a leak-resistant seal, all of the attempts to achieve
a leak-resistant seal in this manner also failed. The point of
failure was, again, the interface between the solar thermal panel
and the inner pipe. Again, all attempts using a separate and
distinct component resulted in incomplete seals, which again
resulted in leakage of thermal fluid from the system. Despite
numerous attempts with varying combinations of pipe sizes and
sealants, a leak-resistant seal was never achieved. In other words,
employing this separate internal component did not achieve a
leak-resistant seal. Mainly, the seals were the points-of-failure
because the entire length of the solar thermal panel needed to
maintain the seal. Thus, over multiple heating-cooling cycles, the
solar thermal panel would expand and contract, thereby causing the
adhesive (which expanded and shrank at a different rate) to fail
and no longer maintain a leak-resistant seal.
[0018] Many other attempts were made to create a leak-resistant
seal, those also failed.
[0019] Insofar as sealing the solar thermal panel with a separate
component resulted in failures, despite the numerous permutations
of pipe sizes and sealing compounds, efforts were directed to
finding ways to seal the solar thermal panel without the use of
separate components. Eventually, attempts were made to achieve a
leak-resistant seal by melting the open ends of the solar thermal
panel, rather than employing separate and distinct sealing
components. Early attempts included melting the edge of the solar
thermal panel by applying heat to the edge. While applying heat to
the edge of the solar thermal panel may seem trivial, even this
method posed challenges. For example, finding the right conditions
under which a proper seal would form was not a trivial task.
[0020] In terms of heat exposure, prolonged exposure caused not
only the edge of the solar thermal panel to melt, but also caused
the internal ribs and layers to melt, thereby resulting in an
internal leakage of thermal fluid from one layer to another. In
terms of finding the correct temperature, if the applied heat was
insufficient, then the edges would not melt together. Conversely,
if the applied heat was too high, then undesirable effects were
seen, such as the melting of the internal ribs and layers as well
as material breakdown. Additionally, when there was uneven heat
distribution, this resulted in non-uniform melting of the edges,
thereby creating an unsightly solar thermal panel.
[0021] Persistence in view of all of those failures eventually led
to a redirection of research efforts to the panels, methods, and
systems that are described with reference to FIGS. 1 through 5. In
other words, the embodiments of the invention, as herein described,
are the result of numerous failures and difficulties, all of which
may appear trivial in hindsight, but which were in reality
extraordinarily difficult to overcome.
Various Embodiments
[0022] With these difficulties in mind, attention is turned to
FIGS. 1 through 5, which show preferred embodiments of a solar
thermal panel, a solar thermal system employing the solar thermal
panel, and methods for manufacturing the solar thermal panel.
[0023] FIG. 1 is a diagram that shows one embodiment of a solar
thermal system. While the system of FIG. 1 shows a closed loop that
circulates thermal fluid 2, it should be appreciated by those
having skill in the art that the system may also be configured as
an open-loop system.
[0024] The system, as shown in FIG. 1, comprises a closed loop that
circulates thermal fluid 2. This closed loop includes a solar
thermal panel 1a, a control unit 5, a storage tank 3, and a first
pump 4. The solar thermal panel 1a comprises a panel temperature
gauge 7, which measures the temperature of the fluid 2 within the
solar thermal panel 1a. The storage tank 3 comprises a fluid
temperature gauge 6, a heat exchanger 12, a cold water inlet 11,
and a hot water pipe (not labeled). The control unit 5 is
operatively coupled to the first pump 4, the panel temperature
gauge 7, and the fluid temperature gauge 6.
[0025] In operation, the thermal fluid 2 circulates through the
solar thermal panel 1a, where the fluid 2 absorbs solar energy and
heats up as a result. The thermal fluid 2 can reach temperatures up
to 150 degrees Fahrenheit, which is typical for hot water heaters.
Based on the readings of the panel temperature gauge 7 and the
fluid temperature gauge 6, the control unit 5 will either activate
or deactivate the first pump 4. For example, when the reading of
the panel temperature gauge 7 is higher than the reading of the
fluid temperature gauge 6, the control unit 5 will activate the
first pump 4, which pumps the thermal fluid 2 from the tank 3 to
the solar thermal panel 1a.
[0026] The storage tank 3 receives cold water through a cold water
inlet 11, and the cold water is pumped through the heat exchanger
12. As the cold water travels through the heat exchanger 12, the
temperature difference between the cold water and the thermal fluid
2 causes the cold water to heat, while simultaneously causing the
heated thermal fluid 2 to cool. The heated water exits through the
hot water pipe (not labeled). The first pump 4 circulates the
cooled thermal fluid 2 back to the solar thermal panel 1a, where
the fluid 2 absorbs solar energy and heats up, thereby repeating
the cycle.
[0027] For some embodiments, such as the one shown in FIG. 1, the
hot water pipe (not labeled) of the storage tank 3 is operatively
coupled to a booster heater 13, which includes a hot water outlet
14. For those embodiments, the hot water pipe (not labeled)
provides the heated water to the booster heater, which further
heats the water. That water can then be used by drawing it from the
hot water outlet 14.
[0028] In addition to using the thermal fluid 2 to heat water for
use, the system of FIG. 1 also shows a closed loop in which the
thermal fluid 2 is used for space heating. An exemplary system for
space heating comprises a booster heater 13, a second pump 9, an
ambient temperature gauge 10, and a hydronic heating system 8. The
second pump 9 and the ambient temperature gauge 10 are operatively
coupled to the control unit 5, which activates or deactivates the
second pump 9 based on the reading of the ambient temperature gauge
10.
[0029] In operation, when the reading of the ambient temperature
gauge 10 is below a set thermostat temperature, the control unit
activates the second pump 9, thereby circulating the heated thermal
fluid 2 from the storage tank 3 to the booster heater 13. The
booster heater 13 further heats the thermal fluid 2, which is then
pumped through the hydronic heating system 8 via the second pump 9.
As the fluid 2 travels through the hydronic heating system 8, it
cools as a result of heat transfer to the heated space. The cooled
thermal fluid 2 is then pumped back to the storage tank 3, where
the cycle may repeat.
[0030] As one can appreciate, the efficiency of the entire system
depends in large part on the efficiency of the solar thermal panel
1a, which allows the thermal fluid to collect and store the solar
thermal energy. Having described the system, the solar thermal
panel 1a of FIG. 1 is described in greater detail with reference to
FIGS. 2 through 5.
[0031] FIG. 2 is a front profile view of a preferred embodiment of
the solar thermal panel 1a of FIG. 1.
[0032] As shown in FIG. 2, the solar thermal panel 1a comprises
horizontal layers 15a, 15b, 15c (collectively 15), which
horizontally separate the internal space within the solar thermal
panel 1a into top channels 17 and bottom channels 18. Preferably,
these layers comprise clear polymer material that allows a large
percentage of solar radiation to pass through the layers 15. The
solar thermal panel 1a also comprises vertical ribs 16, which
vertically separate the internal space within the solar thermal
panel 1a into channels that carry the thermal fluid 2 through the
solar thermal panel 1a. Preferably, the solar thermal panel 1a is
placed above a solid structure, such as a residential roof (not
shown). To increase the heat absorption by the thermal fluid 2, and
also to reduce heat loss from a residential structure, the bottom
of the solar thermal panel 1a can be coated with an absorbing layer
19, and the solar thermal panel 1a can be placed above an
insulating layer 20.
[0033] Given this multi-layered structure, the solar thermal panel
1a carries the thermal fluid 2 through its bottom channels 18. The
top channels 17 act as both a transmissive layer and an insulating
layer. In other words, the air gap within the top channels 17 allow
for transmission of solar radiation while simultaneously providing
insulation to the bottom channels 18. For some embodiments, the top
channels 17 can be evacuated to provide a partial vacuum, thereby
improving the solar thermal panel's insulation properties. Once the
solar radiation reaches the absorbing layer 19, the solar radiation
is converted to thermal energy. The thermal energy is then absorbed
by the thermal fluid 2, which is carried in the bottom channels 18
adjacent to the absorbing layer 19. The heated thermal fluid then
circulates through a solar thermal system, similar to that shown in
FIG. 1.
[0034] As one having skill in the art can appreciate, the solar
thermal panel 1a is sealed in such a way that the thermal fluid 2
does not undesirably leak out of the system. Attention is now
turned to processes for manufacturing sealed solar thermal
panels.
[0035] FIG. 3 is a side profile view of a solar thermal panel as it
is manufactured through an extrusion process. Specifically, the
solar thermal panel comprises an extruded polymer sheet 1d. One
particular type of multi-layered extruded polymer sheet is
LEXAN.RTM., a product from General Electric Company. As shown in
FIG. 3, when the extruded polymer sheet 1d is extruded in
accordance with known methods, the resulting sheet comprises
multiple layers 15a, 15b, 15c, which define top channels 17 and
bottom channels 18. Since the process of extruding multi-layered
polymer sheets is well known in the art, further discussion of that
particular process is omitted here.
[0036] FIG. 4 is a side profile view of a solar thermal panel 1c
being sealed. As noted above, although the process of fabricating
an extruded polymer sheet 1d is widely known in the industry, the
process of sealing the extruded polymer sheet 1d is non-trivial.
FIG. 4 shows one embodiment of a process for manufacturing a sealed
extruded polymer panel 1c.
[0037] In a preferred embodiment, the extruded polymer panel 1c is
sealed as it emerges from the extrusion process. As the extruded
polymer panel 1c passes over a bottom die 22, a heating die 21 is
applied in a direction that is vertical to the extruded polymer
panel 1c, thereby creating an impact seal 23, which melts the
extruded polymer panel 1c at the point of impact to create a sealed
edge.
[0038] As described above, the temperature of the heating die 21,
the heat distribution within the heating die 21, and the speed at
which the heating die 21 is applied should be controlled so as to
provide a proper seal. Specifically, the heating die 21 should be
at a temperature that is slightly higher than the melting
temperature of the polymer material, but not so high as to char or
burn the polymer material. Also, the heating die 21 should be
uniformly heated in order to avoid non-uniform melting of the
extruded polymer panel 1c. Finally, the rate at which the heating
die 21 is applied should be sufficiently slow enough that the
extruded polymer panel 1c melts, rather than being crushed by the
weight of the heating die 21. Insofar as all of these factors
depend on the characteristics of the polymer material, and insofar
as one having skill in the art can calculate these factors, further
discussion of applying the heating die 21 is omitted here. It
should also be appreciated by those skilled in the art that the
heat-sealing of the extruded polymer panel 1c can be done by other
forms of conduction, convection heating, radiant heating, or
various combinations thereof. Thus, for example, should the
extruded polymer panel not be sealed immediately after extrusion, a
different manufacturing process using conduction, convection, or
radiation may be employed to achieve the seal after the extrusion
process.
[0039] The polymer panel 1c, once sealed, now provides a base from
which a functional solar thermal panel can be fabricated. One such
panel is shown with reference to FIG. 5.
[0040] FIG. 5 is a perspective view of a functional solar thermal
panel 1b, which has been fabricated from the sealed extruded
polymer panel 1c of FIG. 4. Specifically, FIG. 5 shows a solar
thermal panel 1b, with a first set of holes 24a associate with an
inlet 25a, and a second set of holes 24b, associated with an outlet
25b. One can readily appreciate that the inlet 25a and the outlet
25b may be reversed, depending on the direction of the flow of the
thermal fluid 2. The first set of holes 24a are drilled through the
bottom channels 18 (FIG. 2) near a distal edge of the solar thermal
panel 1b, and the inlet 25a is connected to the first set of holes
24a. The second set of holes 24b are drilled through the bottom
channels 18 (FIG. 2) near a proximal edge of the solar thermal
panel 1b, and an outlet 25b is connected to the second set of holes
24b. In preferred embodiments, the holes 24a, 24b are located
approximately one inch from their respective edges.
[0041] In operation, the inlet 25a allows for entry of thermal
fluid 2 (FIG. 2) into the solar thermal panel 1b. Once the thermal
fluid 2 enters the solar thermal panel through the inlet 25a, the
fluid travels through the bottom channels 18 (FIG. 2) of the solar
thermal panel 1b. Eventually, the fluid 2 fills the bottom channels
18 of the solar thermal panel 1b and is expelled through the outlet
25b.
[0042] Placing this in the context of FIG. 1, the fluid that gets
pumped into the solar thermal panel 1a by the first pump 4 will
enter the solar thermal panel 1a through the inlet 25a.
Consequently, once that fluid 2 has traveled through the solar
thermal panel 1a and has been heated by the solar radiation, the
fluid 2 is expelled through the outlet 25b and pumped to the
storage tank 3.
[0043] As shown in FIG. 1, the solar thermal panel 1a can be
attached to a residential roof, or mounted on walls, or can be used
in any position that is consistent with the desired purpose.
Typically, polymer materials, such as LEXAN.RTM., have an estimated
life of 30 years. These types of solar thermal panels can be
configured for use in existing structures, or as roofing materials
for new structures.
[0044] Variants
[0045] Although exemplary embodiments have been shown and
described, it will be clear to those of ordinary skill in the art
that a number of changes, modifications, or alterations to the
disclosure as described may be made. For example, while a
residential roofing system has been described with reference to the
solar thermal panels, it should be appreciated that the system can
be used in residential, commercial, or industrial settings.
Additionally, one having skill in the art will understand that the
system of FIG. 1 can be configured to be wholly programmable and
automated, or can require manual input by a user. Also, one having
skill in the art will understand that the thermal fluid can be
water, glycol, or other fluid that has desired heat capacity
properties. Furthermore, one having skill in the art will
appreciate that the absorbing layer 19 can comprise tar paper,
paint, or other substance that is conducive to absorbing solar
energy. Finally, it should be appreciated that, while FIG. 1 shows
an embodiment that employs pumps 4, 9 to transport the fluid 2, a
wholly passive system that is based on thermal convection can be
used to transport the thermal fluid 2.
[0046] All such changes, modifications, and alterations should
therefore be seen as within the scope of the disclosure.
* * * * *