U.S. patent application number 12/688073 was filed with the patent office on 2011-01-13 for solar thermal heating utilizing dynamic particle flow balancing.
Invention is credited to Alex Nugent.
Application Number | 20110005514 12/688073 |
Document ID | / |
Family ID | 43426503 |
Filed Date | 2011-01-13 |
United States Patent
Application |
20110005514 |
Kind Code |
A1 |
Nugent; Alex |
January 13, 2011 |
SOLAR THERMAL HEATING UTILIZING DYNAMIC PARTICLE FLOW BALANCING
Abstract
A solar heating apparatus, which includes a panel having one or
more layers or a group of such layers, wherein one or more layers
among such a group of layers constitutes a transparent medium. The
panel includes at least two other layers among the group of layers,
which constitute a reflective medium. The panel additionally
includes one or more spaces formed between the layers and at least
one other space formed between the other layers. A heat transfer
fluid can be located within the space between the layers. The heat
transfer fluid contains heat-absorbing particles, which are
suspended in the heat transfer fluid and subject to a flow-force
through the panel in a direction against a force of gravity. The
heat-absorbing particles are held in light in the panel via a
balance of a flow-force and the force of gravity. The
heat-absorbing particles drift to the bottom of the panel when the
flow-force stops.
Inventors: |
Nugent; Alex; (Santa Fe,
NM) |
Correspondence
Address: |
ORITZ & LOPEZ, PLLC
P.O. Box 4484
Albuquerque
NM
87196-4484
US
|
Family ID: |
43426503 |
Appl. No.: |
12/688073 |
Filed: |
January 15, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61224780 |
Jul 10, 2009 |
|
|
|
61293688 |
Jan 10, 2010 |
|
|
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Current U.S.
Class: |
126/678 ;
126/634; 126/704 |
Current CPC
Class: |
F24S 10/501 20180501;
F24S 2023/84 20180501; F24S 70/10 20180501; F24S 90/00 20180501;
Y02B 10/20 20130101; F24S 40/50 20180501; F24S 23/82 20180501; F24S
80/56 20180501; F24S 80/20 20180501; Y02E 10/44 20130101 |
Class at
Publication: |
126/678 ;
126/634; 126/704 |
International
Class: |
F24J 2/48 20060101
F24J002/48; F24J 2/04 20060101 F24J002/04 |
Claims
1. A solar heating apparatus, comprising: a panel having a
plurality of layers, wherein at least two layers among said
plurality of layers comprise a transparent medium and at least two
other layers among said plurality of layers comprise a reflective
medium; at least one space formed between said at least two layers;
at least one other space formed between said at least two other
layers; and a heat transfer fluid located within said space between
said at least two layers, said liquid heat transfer fluid having
heat-absorbing particles therein, said heat-absorbing particles
suspended in said heat transfer fluid and subject to a flow-force
through said panel in a direction against a force of gravity, said
heat-absorbing particles held in light in said panel via a balance
of a flow-force and said force of gravity, said heat-absorbing
particles subject to drifting to a bottom of said panel when said
flow-force stops.
2. The apparatus of claim 1 wherein said panel comprises plastic
and wherein said heat-absorbing particles comprise silicon
carbonate particles.
3. The apparatus of claim 1 further comprising a heat mass, said
heat transfer fluid subject to a circulation through said heat
mass.
4. The apparatus of claim 1 wherein said fluid comprises a low
freezing point.
5. The apparatus of claim 1 further comprising a vacuum located
within said space formed between said at least two layers.
6. The apparatus of claim 1 further comprising a gas located within
said space formed between said at least two layers.
7. A solar heating apparatus, comprising: a solar panel, wherein a
plurality of particles are maintained in light via a balance of a
flow-force and gravity, such that said plurality of particles fall
to a bottom of said shaded area wherein said flow-force
terminates.
8. The apparatus of claim 7 wherein said solar panel comprises
plastic.
9. The apparatus of claim 7 wherein said solar panel comprises
glass.
10. The apparatus of claim 7 wherein said solar panel comprises a
plurality of layers, wherein at least two layers among said
plurality of layers comprise a transparent medium and at least two
other layers among said plurality of layers comprise a reflective
medium.
11. The apparatus of claim 10 wherein said solar panel further
comprises at least one space formed between said at least two
layers and at least one other space formed between said at least
two other layers.
12. The apparatus of claim 11 further comprising: a heat transfer
fluid located within said space between said at least two layers,
said liquid heat transfer fluid having heat-absorbing particles
therein, said heat-absorbing particles suspended in said heat
transfer fluid and subject to a flow-force through said panel in a
direction against a force of gravity, said heat-absorbing particles
held in light in said panel via a balance of a flow-force and said
force of gravity, said heat-absorbing particles subject to drifting
to a bottom of said panel when said flow-force stops.
13. A solar thermal heating system, comprising: a building to be
heated; a solar panel, wherein a plurality of particles are
maintained in light via a balance of a flow-force and gravity, such
that said plurality of particles fall to a bottom of said shaded
area wherein said flow-force terminates in order to generate
thermal heat for heating said building.
14. The system of claim 13 wherein said solar comprises a plurality
of layers, wherein at least two layers among said plurality of
layers comprise a transparent medium and at least two other layers
among said plurality of layers comprise a reflective medium.
15. The system of claim 14 further comprising: at least one space
formed between said at least two layers; at least one other space
formed between said at least two other layers; and a heat transfer
fluid located within said space between said at least two layers,
said liquid heat transfer fluid having heat-absorbing particles
therein, said heat-absorbing particles suspended in said heat
transfer fluid and subject to a flow-force through said panel in a
direction against a force of gravity, said heat-absorbing particles
held in light in said panel via a balance of a flow-force and said
force of gravity, said heat-absorbing particles subject to drifting
to a bottom of said panel when said flow-force stops.
16. The system of claim 15 wherein said panel comprises
plastic.
17. The system of claim 15 further comprising a heat mass, said
heat transfer fluid subject to a circulation through said heat
mass.
18. The system of claim 15 wherein said fluid comprises a low
freezing point.
19. The system of claim 15 further comprising a vacuum located
within said space formed between said at least two layers.
20. The system of claim 15 further comprising a gas located within
said space formed between said at least two layers.
Description
CROSS-REFERENCE TO PROVISIONAL PATENT APPLICATION
[0001] This patent application claims the benefit under 35 U.S.C.
.sctn.119(e) of U.S. Provisional Application Ser. No. 61/224,780
entitled, "Solar Heating Utilizing Dynamic Particle Flow
Balancing," which was filed on Jul. 10, 2009 and is incorporated
herein by reference in its entirety. This patent application
further claims the benefit under 35 U.S.C. .sctn.119(e) of U.S.
Provisional Application Ser. No. 61/293,688 entitled, "Solar
Heating Utilizing Dynamic Particle Flow Balancing," which was filed
on Jan. 10, 2010 and is incorporated herein by reference in its
entirety.
TECHNICAL FIELD
[0002] Embodiments relate to solar energy and solar heating
applications. Embodiments also relate to solar thermal heating
panels and associated devices and components.
BACKGROUND
[0003] Solar energy is an attractive source of energy for heating,
for example, a home or office building. Solar thermal devices are
currently employed in some homes and other buildings to heat water.
Such thermal solar devices are not usually utilized to heat the
house. A major problem with using solar thermal water heating to
heat a house is that many panels are required during the winter to
produce the heat needed. During the summer, spring and fail, the
solar intensities can be much higher, while at the same time there
may be not be a need for heat. Another significant problem is that
the cost of solar thermal panels for a home heat application is
high, since a large number is required.
[0004] Such systems present the significant problem of dissipating
the waste heat generated by the solar collectors. One solution is
to divert the hot water to a radiator and thus dissipate the heat
into the atmosphere. This is, however, an expensive solution.
Another solution is to physically cover the collectors. This is not
ideal and even dangerous, as it leaves open the possibility that
one could forget to cover the collectors or may simply be unable to
perform for the task. Another solution involves the use of a motor
to automatically turn the panels over. This is also an expensive
solution and is prone to breakage due to motor failure or wind
drag, which causes wear on the gear assembly.
[0005] Another possible solution is to utilize a black liquid as
the solar absorber and pump this black liquid through an insulated
clear panel. However, there remains the problem of finding a stable
black heat transfer fluid that will not damage the pump and the
problems and potential huge mess of a leak. Since this fluid would
have to be drained, the safety of the overall heating system is
contingent on the pumps or valves not malfunctioning. After many
uses, it is quite possible that the black liquid will stain the
inside of the panel, leading to original problems of overheating
during non-use. In addition, the panels may require a large pump,
as a closed-loop circulation is not possible.
[0006] A number of prior art solar thermal heating panels and
related systems have been proposed. For example, U.S. Pat. No.
5,657,745 entitled "Solar Heat Collecting Panel," which issued on
Aug. 19, 1007 to Rudolf K. Damminger, utilizes a metallic heat
absorption plate rather than a black liquid. U.S. Pat. No.
5,657,745, which is incorporated herein by reference, involves
heating the black liquid to a high temperature. This approach,
however, results in a number of problems. Any sufficiently
insulated collector will attain high temperatures. The problem
results in shutting it off when it is desired to stop heating. In
this case, there is no method to prevent high stagnation
temperatures, which could lead to the circulation fluid boiling,
the panels melting, wood catching on fire, etc.
[0007] An example of a prior art solar energy device is disclosed
in U.S. Patent Application No. 20070210287, entitled "Transparent
Plastic Articles Having Controlled Solar Energy Transmittance
Properties and Methods of Making," by inventor Carlos Guerra, which
published on Sep. 13, 2007. U.S. Patent Application No. 20070210287
is also incorporated herein by reference and involves embedding
plastic with special properties to prevent the transfer of light at
wavelengths not in the visible spectrum so as to reduce the heat
transfer. Although the material and article of U.S. Patent
Application No. 20070210287 could be used in, for example, airplane
windows, but is not suitable for use in solar thermal heating
applications.
[0008] An example of a solar heating panel is disclosed in U.S.
Patent Application Publication No. 20080236572, entitled "Solar
Heating Panel Fabricated From Multi-Wall Plastic Sheets," by
Guenter Schaefer, which published on Oct. 2, 2009. The device
disclosed in U.S. Patent Application Publication No. 20080236572,
which is incorporated herein by reference, utilizes a multi-wall
plastic sheet and a dark material below a central absorber. The
problem, again, with such a device is how does one actually turn
the panel off? Because the absorber is built into the panel, there
is not a practical and safe method or apparatus for turning the
panel off when one does not desire to collect heat. This is of
tremendous concern when the panel is constructed of plastic, which
will melt and deform at high temperatures.
[0009] The cost of heating a home or building is the majority of
energy use for the average household. Although solar thermal energy
provides an abundant source of energy for heating, unfortunately
most households utilize fossil fuels to provide heat. This is
unnecessary; as a properly designed house can incorporate solar
windows to completely eliminate or dramatically reduce heating
costs. Unfortunately our society has been shortsighted in this
respect and we have the problem of heating millions of incredibly
inefficient homes. The use of plastic as a source of a solar panel
for heat generation is attractive because it is an abundant and
inexpensive material and is both flexible and lightweight. Glass
and metal, the dominate materials in the thermal solar panel
market, do not share these attributes.
[0010] A significant problem with plastic, however, is that
exposure to high temperatures may degrade or deform the material,
rendering the panels useless. To achieve an efficient temperature
gain during cold ambient temperatures, the panels must be insulated
from thermal loss. However, the insulation can lead to extremely
high temperatures within the collector if the heat is not removed.
If a pump fails, the electricity goes out, or a blockage forms in
the circulation path, the circulation will stop and the temperature
will rise in the panels. This is called the stagnation temperature,
which can exceed boiling for highly insulated panels. This is a
significant problem currently inhibiting the use of plastic as a
source of solar heat generation.
BRIEF SUMMARY
[0011] The following summary of the invention is provided to
facilitate an understanding of some of the innovative features
unique to the present invention, and is not intended to be a full
description. A full appreciation of the various aspects of the
invention can be gained by taking the entire specification, claims,
drawings, and abstract as a whole.
[0012] It is, therefore, one aspect of the embodiments to provide
for an improved solar heat source.
[0013] It is still another aspect of the embodiments to provide for
a heating system utilizing dynamic particle flow balancing.
[0014] It is a further aspect of the embodiments to provide for an
inexpensive and effective solar thermal panel that can be "turned
off" when not in use.
[0015] It is a further aspect of the embodiments to provide for the
effective use of low-cost plastics as a medium for solar heat
collection.
[0016] The above and other aspects can be achieved as will now be
described. A solar heating apparatus is disclosed, which includes a
panel having a group of layers, wherein one or more layers among
the group of layers constitute a transparent medium. The panel
includes at least one other layer among the group of layers, which
constitute a reflective medium. The panel additionally includes one
or more spaces formed between the layers and at least one other
space formed between the other layers. A heat transfer fluid can be
located within the space between the layers. The heat transfer
fluid contains heat-absorbing particles, which are suspended in the
heat transfer fluid and subject to a flow-force through the panel
in a direction against a force of gravity. The heat-absorbing
particles are held in light in the panel via a balance of a
flow-force and the force of gravity. The heat-absorbing particles
drift to the bottom of the panel when the flow-force stops. The
panel is preferably composed of plastic, although glass and/or
other media may be utilized as well for high temperature operations
that exceed the working temperature of plastic. Additionally, such
an apparatus can include the use of a heat mass, wherein the heat
transfer fluid is subject to circulation through the heat mass. The
utilized fluid preferably possesses a low freezing point.
Additionally, a vacuum or a gas may be located within the space
formed between the two layers.
[0017] A solar thermal panel is thus disclosed, which is based on
liquid-particle dynamics, and which can reduce the cost of solar
thermal panels by 75% or more. When fluid is pumped through the
panels they become black and highly absorbent. When fluid is not
circulating the panels become highly reflective. The
overheating-prevention mechanism allows for the construction of an
all-plastic solar thermal panel. A prototype panel has been
constructed from commonly available materials to validate the
principle.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The accompanying figures, in which like reference numerals
refer to identical or functionally-similar elements throughout the
separate views and which are incorporated in and form part of the
specification, further illustrate the present invention and,
together with the detailed description of the invention, serve to
explain the principles of the present invention.
[0019] FIG. 1 illustrates a heating system, in accordance with an
embodiment;
[0020] FIG. 2 illustrates a side sectional view of the solar panel
depicted in FIG. 1, in accordance with an embodiment;
[0021] FIG. 3 illustrates a front view and a side view of the panel
depicted in FIGS. 1-2, in accordance with an embodiment;
[0022] FIG. 4 illustrates a front view of the panel, in accordance
with an embodiment;
[0023] FIG. 5 illustrates a front view of the panel with the
circulation pump, in accordance with an embodiment;
[0024] FIG. 6 illustrates a system, which may be employed with the
system and components depicted in FIG. 1-5, in accordance with an
embodiment;
[0025] FIG. 7 illustrates a front view of the disclosed panel, in
accordance with an embodiment;
[0026] FIG. 8 illustrates a front view of the disclosed panel, in
accordance with an embodiment;
[0027] FIG. 9 illustrates an example of particle panel at various
stages of activity, in accordance with an embodiment;
[0028] FIG. 10 illustrates turbulent flow the front side of a
particle panel during operation, in accordance with the disclosed
embodiments;
[0029] FIG. 11 illustrates laminar flow on the back side of a
particle panel during operation, in accordance with the disclosed
embodiments;
[0030] FIG. 12 illustrates a schematic diagram of convection cells,
in accordance with the disclosed embodiments;
[0031] FIG. 13 illustrates a graph depicting the onset of
convection currents, which cause increased heat dissipation in a
cell, in accordance with the disclosed embodiments;
[0032] FIG. 14 illustrates an alternative panel design allowing for
horizontal placement, in accordance with the disclosed embodiments;
and
[0033] FIG. 15 illustrates the design of FIG. 14 during four times
after the panel circulation is turned off, showing how the panel
transitions from an absorbing to non-absorbing, in accordance with
the disclosed embodiments.
DETAILED DESCRIPTION
[0034] The particular values and configurations discussed in these
non-limiting examples can be varied and are cited merely to
illustrate an embodiment of the present invention and are not
intended to limit the scope of the invention. Note that in FIGS.
1-6, identical or similar parts or elements are generally indicated
by identical reference numerals.
[0035] FIG. 1 illustrates a heating system 100, in accordance with
an embodiment. In the configuration of system 100, a building 109
generally includes a roof 111 upon which a thermal solar panel 101
is located. Light (as indicated by arrows 110) impinges on the
panel 101, where it is absorbed as heat by particles 219 suspended
in a liquid that flows through the panel 101 in a direction against
the force of gravity. Note that the particles 219 can be, for
example, but not limited to silicon carbonate particles.
[0036] The liquid is circulated through a heat mass 104, through a
controller 105, and finally through a circulation pump 106. A
circulation pipe 102 is connected to the panel 101. Note that an
inset 113 is illustrated in FIG. 1, which depicts a detailed
pictorial view of the circulation pipe 102. The inset 113 indicates
that the circulation pipe 102 includes the use of a secondary pipe
103 as a double walled circulation pipe for heat insulation
purposes. It can be appreciated that although a pitched roof 111 is
shown in FIG. 1 with respect to the building 109, it can be
appreciated that the panel 101 may be located on a flat roof.
Furthermore it can be appreciated that the panels 101 may be
located on a surface other than a building roof, for example, the
ground or a dedicated structure.
[0037] The controller 105 can communicate with one or more sensors
142, 143 and 144 which are described in greater detail herein. In
general, the heat mass 104 can be configured as an environment or
object that absorbs and dissipates heat from another object
utilizing thermal contact (e.g., either direct or radiant). As heat
is collected by the panels, the heat moves into the heat mass 104,
which radiates the heat (as indicated by arrows 108) into the
building 109. The controller 105 may be optionally connected to a
computer network (e.g., the Internet) via a network connection
107.
[0038] The controller 105 can be configured as a device that
monitors and affects the operational conditions of system 100. Such
operational conditions can include output variables of the system
100, which may be affected by adjusting particular input variables.
For example, controller 105 may be a thermostat for detecting air
temperature (e.g., an output variable) and directing the activities
of system 100. The air temperature reading within (and or external)
to the building 109 may constitute feedback utilizing by controller
105, and the air within the house with respect to a desired
temperature may be considered a set point value.
[0039] FIG. 2 illustrates a side sectional view of the solar panel
101 depicted in FIG. 1, in accordance with an embodiment. The
panel(s) 101 can be constructed of, for example, four layers 220,
221, 222, and 223. Layers 222 and 223 are transparent and can be
configured from materials, such as, for example, plastic, glass or
any another transparent medium. Layer 221 can be configured as a
reflective medium composed from a material, such as, for example, a
thin polyester film. One example of such a film is
Biaxially-oriented polyethylene terephthalate (boPET) polyester
film, which can be employed for its high tensile strength, chemical
and dimensional stability, transparency, reflectivity, gas and
aroma barrier properties and electrical insulation.
Biaxially-oriented polyethylene terephthalate (boPET) is known by
its trade names Mylar and Melinex. It can be appreciated, of
course, that other types of materials may also be utilized in
association with or in lieu of biaxially-oriented polyethylene
terephthalate (boPET).
[0040] Alternatively or in association with such material, layer
221 may be simply painted white. Layer 220 may be configured from
any suitable material that possesses good heat retention
properties. The space between layers 222 and 223 can be filled with
a gas or a vacuum. The space between 220 and 221 can also be filled
with a gas or a vacuum or any insulated material, for example
fiberglass or Styrofoam. The space between 221 and 222 may be
filled with a clear liquid heat transfer fluid having small
heat-absorbing particles 219. Such a liquid heat transfer fluid
preferably possesses a low freezing point. A small lower portion
210 of panel 223 can be painted to provide shade from solar
rays.
[0041] Photons 211, 212, 213 and 214 demonstrate the basic
operation of the system 100 and the panel 101. Photons 211 that hit
surface 210 are reflected and provide shade. Photons pass through
transparent layers 223 and 222 may either be absorbed by a particle
in the fluid 213, reflected from layer 221 and then absorbed 214,
or else reflected out of the panel 101 and lost 212. It is desired
that the panels minimize the lost photons during operation.
Gratings 224, 218 act as filters to prevent the particles from
circulating through the entire system. Plugs 229, 230, 227 and 228
prevent liquid from entering the spaces between layers 222, 223 and
220, 221.
[0042] FIG. 3 illustrates a front view 301 and a side view 303 of
the panel 101 depicted in FIGS. 1-2, in accordance with an
embodiment. The circulation pipe 102 depicted in FIG. 1 can be
connected to the input port 226 and output port 216 illustrated in
FIG. 2. Liquid heat transfer fluid flows into the panel 101 as
indicated by arrow 209 and out of the panel 101 as indicated by
arrow 215. The flow of fluid can be distributed into multiple
vertical channels 333 via an input flow distributor 225. Liquid is
directed from the channels to an output port 216 via an output flow
distributor 217. Particles 219 in the channels are subject to two
primary forces: advection or flow as indicated by arrow 331, and
gravity as indicated by arrow 332. Note that alternatively, the
particles 219 may float rather than sink, or in combination
therewith. In such an arrangement, the flow pushes the particles
down and the buoyancy pushes them back up. Such a configuration
allows for the construction of lighter panels and also panels that
may become hotter due to increasing time in the collector by
providing a snaking path up and down, where the "up" paths utilizes
particles that sink and the "down" path utilize particles that
float.
[0043] FIG. 4 illustrates a front view of the panel 101, in
accordance with an embodiment. The flow force pushes the particles
upward, while gravity pushes the particles downward. As the
particles 219 are pushed upward they eventually are blocked by the
grating 318. As particles 219 are accumulated on the grating 438
within a channel 439, the resistance to flow in the channel 439
increases, which causes a reduction in the flow of fluid through
the channel 436, 434 and an increase in flow 437, 435 in another
channel 440. This results in the particles being pulled down by
gravity in channel 439 and upward by flow in channel 440. The end
effect is a distribution of the particles throughout the
channels.
[0044] FIG. 5 illustrates a front view of the panel 101 in the
absence of circulation provided by the circulation pump 106, in
accordance with an embodiment. When the circulation pump 106 is
turned off, the flow through the channels stops, which causes the
particles to fall to the bottom of the channels below the shaded
surface 210. As the channels no longer contain particles, the panel
no longer absorbs heat. Thus, in the event of a system failure such
as a leak in the circulation pipe or panel, a problem with the
circulation pump, or a deliberate shut down via the controller, the
flow within the system will be shut off and the panels will go into
an inactive state, characterized by particles settling below the
shaded region 541 wherein heat is not accumulated but rather
reflected by area 210.
[0045] The controller 105 can measure the flow of heat circulation
fluid as well as fluid temperature. In addition, the controller 105
may be connected to one or more sensor(s) 142, 143, and 144 that
respectively measure the temperature, light radiance, humidity,
wind speed, or any other environmental variable, the inside
temperature, the temperature of the heat-mass 104, and so forth.
Via the network connection 107, remote computational services may
be accessed, such as, for example, weather prediction services and
data. In addition, the controller 105 may output the measured
values of the sensors to a remote data collection service (e.g.,
via the Internet). The controller 105 may modify the flow of the
circulation pump 106 to transport heat from the solar panels to the
heat mass 104.
[0046] FIG. 6 illustrates a system 600, which may be employed with
the system 100 and components thereof depicted in FIG. 1-5, in
accordance with an embodiment. Note that some buildings may already
possess a radiant heat system, where hot fluid is circulated
through a concrete floor. Such buildings may utilize heat mass 104
as a means of heat delivery. However, many buildings do not posses
built-in heat mass. In such a case, heat mass 104 may be
constructed, which allows for a number of possibilities for
enhancing the effectiveness of the overall system 100. A drawback
of storing heat in a large heat mass is that heat is radiated into
the adjacent room and the rate of heat transfer into the room may
not be controlled. As the heat mass become larger, this introduces
problems due to the ability to accurately predict the weather. For
example, if it is predicted that the night will be particularly
cold, then the heat mass should be heated to a higher temperature.
If this turns out not to be true, then the house 109 will be
excessively hot. It is thus appropriate to control the rate of heat
transfer into and out of the heat mass.
[0047] This can be accomplished with a thermal mass 605 contained
within an insulated enclosure 604. Heat is transferred into the
heat mass though a pipe 606. A radiator imbedded within the thermal
mass 608 is connected to an external radiator 602 through a highly
heat-conductive medium. This medium could be passive, for example a
solid metal, or active, for example a circulating fluid or heat
pump. Heat is radiated into the house via an active heat transfer
mechanism. As an example, a fan 601 connected to a motor 605 may
blow air through a radiator 602. The motor 605 may be connected to
the controller 105 through an electronic interface 607.
[0048] FIG. 7 illustrates a front view of the panel 101, in
accordance with an embodiment. The flow force pushes the particles
downward, while buoyancy of the particle pushes the particles
upward. One can appreciate that this is simply an inversion of the
case where the particles sink. As the particles are pushed downward
they eventually are blocked by the grating. As particles 701 are
accumulated on the grating within a channel 439, the resistance to
flow in the channel 439 increases, which causes a reduction in the
flow of fluid through the channel 436, 434 and an increase in flow
437, 435 in another channel 440. This results in the particles
being pulled up by their buoyancy 702 and downward by flow 703. The
end effect is a distribution of the particles throughout the
channels.
[0049] FIG. 8 illustrates a front view of the panel 101, in
accordance with an embodiment. Channels comprising particles that
sink 801 and particles that float 802 are arranged in a snaking
path 803. Liquid heat transfer fluid enters the system through
input port 226 and exits through output port 216. Alternating
sections of non-buoyant and buoyant particles comprise a path
whereby a heat transfer fluid flows. Shaded regions 210 are
provided in the condition that the flow stops, thus shielding the
particles from solar absorption. Such an embodiment may be used to
raise the temperature of the heat transfer fluid to a higher
temperature in a smaller panel.
[0050] Note that in some high-temperature embodiments, the
disclosed panel(s) can be employed to heat liquid, which is stored
in a thermal tank. A home generator, for example, can utilize heat
to run a steam engine, which creates electricity that is pumped
back into the grid. Steam is condensed and purified water results.
Waste water from showers and sinks can be utilized. Such a system
can generate house heat, water heat, electricity and also recycle
water.
[0051] A further embodiment involves the arrangement of a large
number of such panels to pre-heat a fluid like oil, which is then
passed through a smaller number of panels made from glass, heating
the oil past 100.degree. C. Such a fluid like oil can be then
utilized to turn water to steam to run a turbine and generate
electricity. The fact that the disclosed panels are inexpensive to
produce and relatively durable can result in the production of
cheap solar electricity. Currently solar thermal electric plants
utilize mirrors focused onto pipes or a central tower. Mirror
(e.g., glazed glass) is much more expensive then the disclosed
panels, which are constructed from polycarbonate and black
particles (e.g., like sand). The key is that one may utilize, for
example, 100.times. the plastic panels to preheat and only utilize
glass (which is even less expensive then mirror) to super heat.
Construction cost of a plant could be reduced enormously (e.g.,
perhaps 10.times. reduction), which would make solar electricity
generated in this manner competitive with coal.
[0052] It is interesting to observe that household heating is a
problem of the northern and southern latitudes. In this case,
during the winter the sun is low on the horizon, which requires
that the panels be placed near vertically. Such a configuration is
preferable with respect to the some of the disclosed embodiments,
as gravity pulls the particles down against the upward flow. The
disclosed embodiments solve a significant problem, which is
retrofitting millions of inefficient homes to provide heat in an
environmentally sound manner.
[0053] Note that heating and cooling account for 63% of the average
household energy consumption. Whereas considerable attention is
focused on electricity generation, the majority of residential
energy is consumed producing or removing heat. The sun produces on
average 5 kWh per square meter per day in the U.S. A roof
one-fourth covered with solar thermal panels could provide a
substantial majority of the heating and cooling for a house. Why
does every home not have solar thermal panels covering a
significant portion of its roof? Solar thermal panels are
surprisingly expensive, ranging from $300 to $1000 per square
meter, not including shipping and installation, which are
substantial because of the panel weight and size. It would cost
from $15,000 to $50,000 to cover 1/4 of the average roof with solar
panels, not including installation. If the cost of a solar thermal
panel could be reduced to $100/sq. meter, it would have significant
economic ramifications. The entry barrier to green energy would be
removed for most. $1,000 worth of panels could provide most or all
energy for hot water, and $5,000 could provide both water and space
heat, and potentially cooling in the summer.
[0054] Thus, why are solar thermal panels expensive? Efficient
capture of heat when the ambient temperature is low requires
insulation. Insulation prevents heat from escaping back into the
air once it is captured, but it also causes a problem. If the heat
is not removed from the panel, the temperature will rise to very
high levels. This is the primary reason modern solar thermal panels
are expensive: the panels must be capable of withstanding high
stagnation temperatures. If an insulated solar thermal panel could
be constructed entirely of cheap thermoplastics, it would cost a
tiny fraction of current systems. This is observed in solar heating
applications where insulation is not required, for example pool
heating. The problem, of course, is that thermoplastics melt if
exposed to high temperature.
[0055] Insulated solar thermal panels can be constructed of
plastic. What is needed is a completely reliable mechanism to
regulate the panel's temperature. A particle panel provides this
function. A particle panel for heating applications is oriented
mostly vertical so that it is perpendicular to the sun, which is
low on the horizon in the winter for all latitudes that actually
need the energy. Liquid flows up through the panel. Small black
particles trapped inside the panel via two wire filters are pushed
up by the liquid flow, but are also pulled down by gravity. When
the liquid is flowing, the particles are pushed against the wire
mesh, stabilizing the flow rate to the particles sink rate, thus
distributing themselves over the panel and becoming an efficient
light absorber. When the flow stops or the fluid is drained back,
the particles sink to the bottom, occupying a substantially lower
cross-sectional area. A reflective surface behind the panel then
reflects the light away and the panel stays cool. The ability to
turn off when not in use prevents the panels from exceeding the
upper working temperature of thermoplastics, thus allowing the
construction of an all-plastic insulated panel.
[0056] FIG. 9 illustrates an example of particle panel 101 at
various stages of activity, in accordance with an embodiment. In
the embodiment depicted in FIG. 9, a prototype particle panel has
been constructed from double-wall polycarbonate and acrylic plastic
to validate the concept. The panel 101 turns on in approximately 10
seconds at household pressure. The power output was measured on a
sunny November day in Santa Fe, N. Mex. and ranged from 750-830
W/m.sub.2. 45 micron stainless-steel wire mesh was melted into the
channels of the plastic sheet, preventing the particles from
escaping. 65 micron silicon carbonate particles were used. These
particles are manufactured for use in the abrasives industry and
are available pre-sifted into a multitude of grain sizes for
relatively low cost. 50 pounds of particles were purchased for
$120, which is enough for approximately 150 m.sub.2 of panel.
Another less expensive source of particles is coal slag, a waste
product of coal-fired electric plants. In addition to low cost, a
particle panel is likely to be highly efficient. In a traditional
solar panel, heat is absorbed onto a solid black plate, where it
must travel upward of 10 cm before transferring into water flowing
through a pipe. This bottle neck can result in heat build-up, which
translates to lower efficiencies due to heat loss. The particle
panel design could greatly reduce this thermal conduction
bottleneck. Although silicon carbonate has a lower heat
conductivity than copper by a factor of 100, for example, the
distance that the heat must travel to reach the water is only the
particle radius, which is a factor of, for example, 3000 smaller.
Thermal conduction thus favors the particle panel by a factor of,
for example, 30. Of course, a great deal of further optimization
could be done by decreasing the particle size and increasing the
particle thermal conductivity, not to mention creating particle
mixtures.
[0057] FIG. 10 illustrates a configuration 890 depicting turbulent
flow the front side of the particle panel 101 during operation, in
accordance with the disclosed embodiments. FIG. 11 illustrates a
configuration 891 depicting laminar flow on the back side of the
particle panel 101 during operation, in accordance with the
disclosed embodiments. FIG. 12 illustrates a schematic diagram 893
of convection cells (e.g., Benard Convection Cells), in accordance
with the disclosed embodiments. FIG. 13 illustrates a graph 895
depicting the onset of convection currents, which cause increased
heat dissipation in a cell, in accordance with the disclosed
embodiments.
[0058] The prototype particle panel stabilizes at a working
pressure. During its on-state, if the panel is tilted slightly
convection currents form quickly, with turbulent flow moving the
fluid (e.g., water) up the front side and laminar flow down the
back side. The existence of turbulent flow on the front side of the
panel and laminar flow on the back side could be consistent with an
energy-transfer maximization principle. It is well known that
turbulence increases the efficiency of heat exchangers. Under an
entropy-maximizing assumption.sub.2 the particle-liquid dynamics of
the panel will configure for maximal energy transfer rates. Similar
emergent phenomena can be observed in Benard Convection Cells.
Benard convection cells spontaneously appear in a liquid layer when
heat is applied from below. Initially all dissipation through the
fluid occurs via conduction and molecule to molecule interaction.
When the gradient reaches a critical level the transition to highly
organized convection occurs. Accompanying this transition is
increased heat dissipation.
[0059] If the same self-organizing principles are at work in a
particle panel it will have tremendous value. The efficiency of
heat transfer requires that the panels keep as low a working
temperature as possible. The liquid dynamics of the panel could
keep the panels at a temperature that maximizes energy
transfer.
[0060] Note that absorption coolers use a heat source to power a
cooling cycle rather than electricity. Both absorption air coolers
and compression air coolers use a refrigerant with a very low
(e.g., sub-zero Fahrenheit) boiling point. In both types, when this
refrigerant evaporates or boils, it takes some heat away with it,
providing the cooling effect. The main difference between the two
types is the way the refrigerant is changed from a gas back into a
liquid so that the cycle can repeat. An absorption refrigerator
changes the gas back into a liquid using a different method that
needs only heat, and has no moving parts. The minimum temperature
needed to drive an absorption cooler is, for example, 88.degree. C.
Solar thermal cooling systems are already being produced. The upper
working temperature of polycarbonate is, for example, 115.degree.
C., which means plastic particle panels could be used as an energy
source for air conditioning. Cooling, both for refrigeration and
house space, accounts for 20% of the average American's energy
costs. Whereas the prototype particle panel utilized gravity for
continuous operation, a modified design using convection currents
could be constructed. This allows the panels to lay horizontal,
thus maximizing energy absorption in the summer months.
[0061] An example of a panel design for cooling applications is
shown in the configurations depicted in FIG. 14 and FIG. 15. FIG.
14 illustrates an alternative panel design for panel 101, which
allows for horizontal placement, in accordance with another
embodiment. Top and side views of the alternative design of panel
101 are shown in FIG. 14. FIG. 15 illustrates one possible design
of panel 101 depicted in FIG. 14 during four times (t=0, t=1, t=2,
and t=3) after the panel circulation is turned off, demonstrating
how the panel transitions from an absorbing to non-absorbing, in
accordance with the disclosed embodiments. In general, heat
transfer fluid is circulated into port IN1 and optionally into port
IN2 associated with panel 101. Horizontal, tilted and reflective
slats run along the width of the panel 101 depicted in FIGS. 14-15.
As the fluid is pumped into the panel 101, a circulation current is
created, which distributes particles 219 trapped within the panel
101 to the sun-facing side, thereby collecting thermal energy and
transferring this energy into the circulating fluid. When the
circulation is shut off, the particles 219 sink between the slats
to the bottom of the panel 101. The reflective slate then provides
shade for the particles 219 while reflecting light out of the panel
101. Such a design allows the panel(s) 101 (e.g., one or more
panels) to be oriented with the surface directed vertically, thus
maximizing solar adsorption during the summer months when the sun
is near vertical and energy for air conditioning systems as
needed.
[0062] The cost of a solar system involves more than the cost of
the panels. Currently available panels are extremely heavy, at 38
pounds per square meter, for example. This does not include a
crating charge, which amounts to $33 per square meter. Shipping in
the continental United States ranges, for example, from $0.30 to
$1.00 per pound, depending on the distance. It therefore costs from
$44.00/m.sub.2 to $71.00/m.sub.2 just to deliver a modern solar
thermal panel. A plastic particle panel would be constructed of
thin plastics and foam and weigh approximately 1 pound. Its size,
weight and superior durability means it can fit in a standard
cardboard box and shipped via standard mail. It is conceivable that
under efficient manufacturing conditions, the cost to buy and ship
a particle panel could be comparable the cost to just ship a
traditional panel.
[0063] Once a solar panel has arrived, it must be installed.
Conventional solar panels suffer from high stagnation temperatures,
which can potentially boil circulating fluid. The high maximal
temperatures that can develop require substantially more expensive
plumbing systems, including pressure relief values, pressure
checks, and copper pipe. The low temperatures and pressures of
particle panel could eliminate a significant cost of plumbing, as
the panels could be hooked up with plastic tubing and operated at
low working pressures. The weight of traditional panels is another
big consideration during installation.
[0064] Heating a house with solar energy requires that a system
within the house distribute the heat. Many houses contain hydronic
heating systems, where hot water is circulated through the floor.
In these cases, the conversion is simple and inexpensive. In the
absence of a hydronic system, inexpensive space heaters could be
installed. The unit would consist of a volume of water (e.g., 50 to
100 gallons or more) stored in an insulated container. Liquid could
be pumped from the container to a radiator, where a fan would blow
the heat into the room. For a room kept at, for example, 25.degree.
C., 100 gallons of water at 50.degree. C. could store 10.6 kWh of
energy. This is equivalent to an average 1.0 kW electric space
heater operating continuously all night long. Such a system could
be constructed very affordable. The area on the roof above a
typical room is sufficient to capture the energy needed for heating
during the day and storing sufficient energy for the night. If a
larger thermal mass is used, 100% solar heating and cooling becomes
possible.
[0065] Water has the highest volumetric heat capacity of all
commonly used materials and can be added by the home owner for
negligible cost. Thermal mass water tanks could be constructed,
either in an insulated shed or buried. A cubic volume of 25.degree.
C. water 3 meters squared, for example, could store 780 kWh of heat
energy. This is equivalent to $100 in electric energy at, for
example, 13 /kWh and is sufficient to ride out a 10-day winter
storm. Twenty-two hours of direct sun exposure falling on 50
m.sub.2 of 70% efficient panels could fill the thermal tank.
[0066] The panels disclosed herein (e.g., panel 101) can eliminate
the cost barrier to green energy for most home owners. The total
system cost will be substantially lower than existing solar
systems, and the panel efficiency could be much higher. Combined
with thermal energy storage, most homes could be converted to 100%
solar heating and cooling.
[0067] It will be appreciated that variations of the
above-disclosed and other features and functions, or alternatives
thereof, may be desirably combined into many other different
systems or applications. Also that various presently unforeseen or
unanticipated alternatives, modifications, variations or
improvements therein may be subsequently made by those skilled in
the art which are also intended to be encompassed by the following
claims.
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