Note: Descriptions are shown in the official language in which they were submitted.
CA 02789343 2013-10-04
PREFABRICATED THERMAL ENERGY STORAGE ENCLOSURE
DESCRIPTION
FIELD OF THE INVENTION
This disclosure relates generally to enclosures for the storage of thermal
energy, and
more specifically to such enclosures utilizing solid phase storage medium or
media as opposed
to a liquid phase storage medium. Said enclosures are constructed of
prefabricated insulated
sandwich panel assemblies forming the walls, floor and roof sections, suitable
for manufacture
as pre-assembled units and/or in kit form, with varying options in terms of
ancillary components,
such as internal heat transfer coils as described herein.
BACKGROUND OF THE INVENTION
It is generally known that storage of thermal energy for later release and
transfer to a
structure, process or other entity requiring heat can be a useful and cost
efficient undertaking.
This concept is often used, for example, in active solar heating systems,
commonly in
residential, institutional, and commercial installations for domestic water
heating or space
heating. Other examples are process systems requiring thermal energy in
commercial and
industrial settings, and in heating water in swimming pools and similar
facilities.
The benefits of such systems are in a reduction in the consumption of
traditional non-
renewable energy resources such as fossil fuels, in direct energy cost
savings, or as an aid in
enabling the deferral of construction of new capital-intensive electric
generating facilities through
the increased use of off-peak generation, an advantage that also benefits the
consumer in the
form of lower power rates.
It is commonly accepted that the need for more efficient use of renewable
energy
sources, such as solar power, and better utilization of non-renewable energy
resources, as in
off-peak electrical generation, will continue to grow as traditional fossil
fuel resources are further
depleted.
Storage of thermal energy for later release, as described above, is often
achieved
through the use of storage tanks containing a medium of water, brine, or other
liquids, or in a
storage medium of earth, rocks or other solid materials, all provided with
some means of
transferring said energy into, and recovery from, the energy storage medium.
In some cases
phase change materials (PCMs) are used to take advantage of the latent heat of
fusion capacity
available in such materials.
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A number of previous patents have been issued for apparatuses that focus on
the
storage of thermal energy, however there are distinct and significant
differences in the
processes and apparatuses described in those patents in accomplishing this
objective from
those of the current invention, as summarized hereinafter.
Firstly, those patents generally identify solar as the sole energy source of
interest, as
opposed to one or both of solar and electrical as per the current invention.
Some previous patents, namely Can. 1,040,953 (Atkinson, issued October 24,
1978)
and Can. 1,020,828 (Strickland et al, issued November 15, 1977) provide for
thermal energy
storage in an enclosure, both utilizing rocks as the storage medium, but also
focus on the
novelty of the means of the actual collection of said energy. The apparatuses
defined by said
patents are not particularly well-suited to the utilization of state-of-the-
art but conventional solar
collectors, for instance, as the means of energy collection. Also, retrieval
of the stored thermal
energy is by air circulation, which has practical limitations in many
applications. In addition, and
of significance with respect to the current invention, the ease and
practicality of construction of
said enclosures are not prime considerations in these patents, as with the
current invention.
Other existing patents, namely Can. 1,108,879 (Balch, issued September 15,
1981), and
Can. 1,082,545 (Yaun, issued July 29, 1980) are for systems and apparatuses in
which the
energy storage is achieved through utilization of ground mass in buried
systems. These typically
rely on relatively complex processes and apparatuses in storing and retrieving
the thermal
energy. By their nature they are typically intended for larger scale energy
storage than that
generally intended with the current invention.
Still other previous patents, namely Can. 1,206,106 (Hofius and Moses, issued
June 17,
1986), and Can. 1,160,923 (Stice, issued January 24, 1984), focus primarily on
the containers
for retention of a thermal energy storage medium, and manufacturing of the
same. Said patents
offer distinctly different approaches to thermal energy storage requiring more
highly specialized
processes in the manufacturing of the inventive containers in comparison to
those required with
the current invention, and also are tailored to the use of PCMs as the primary
energy storage
media. As noted heretofore, PCMs do have one advantage over the particulate
solid materials
proposed herein, but they also typically have some disadvantages, including
relatively high
costs and the potentially problematic trait of experiencing relatively
significant magnitudes of
expansion and contraction in passing through the phase change temperature, a
trait that must
be physically accommodated in the apparatuses of the energy storage method
employed. The
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inventive containers of the aforementioned patents that hold the PCMs also
collect the solar
energy directly, and are not particularly well-suited to the utilization of
high efficiency
conventional solar collectors, or off-peak electrical generation as sources
for said energy, as
proposed in the current invention.
The most common method of providing thermal energy storage in active solar
systems
in residential, commercial, institutional, and industrial settings, has been
through single or
multiple storage tanks containing water as the energy storage medium. Although
water is known
to have higher specific and volumetric heat capacities than most solid phase
materials, and can
thus store greater quantities of heat per given mass and volume respectively,
concerns related
to the risks of storing relatively large quantities of water can, for a
variety of reasons, effectively
impose fixed capacity limits on thermal storage systems using that medium.
Concerns over leakage of the contained liquid in these storage tanks typically
increase
with increasing storage volume, and also with increasing operating
temperatures due to safety
considerations of potential human contact exposure. If additional thermal
energy storage is
desired beyond that achievable at a given operating pressure, it is necessary
to increase said
pressure of the storage tank or tanks, thereby further increasing safety
concerns related to the
accidental release of steam. Furthermore, storage of thermal energy in water
storage tanks with
the water retained for some time within a relatively moderate temperature
range of between 20
and 50 C (68 - 122 F) can lead to the spread of microorganisms responsible
for legionnaire's
disease, (ref. OSHA Technical Manual, Section 3, Chapter 7, Legionnaire's
Disease - updated
effective 06/24/2008) resulting in increased risk to individuals exposed to
said water.
Thermal storage capacity limitations of water tanks as discussed above can
impose
restrictions on the capabilities of potential installations, such as in
restricting residential and
institutional solar heating systems to the supply of domestic hot water (DHW)
alone, rather than
being supportive to the design of said systems to also provide supplemental
thermal energy for
space heating.
Where some form of solid phase thermal storage medium is used, rather than
liquid
phase, enclosures have not been available in an economical prefabricated form
that facilitates
construction and satisfies economic viability requirements to the extent being
proposed in the
current invention. Because of the relatively high temperatures that can be
attained in thermal
storage systems in some energy collection processes, specialized knowledge of
material
characteristics and specific design and construction details appropriate for a
suitable enclosure
are required. Such specialized knowledge requirements can thereby constrain
potential
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constructors not trained in the art, resulting in the need for specialists in
the field, and potentially
leading to higher costs than can be justified in many situations. Alternately,
defective designs
and unsatisfactory performance can also result.
Accordingly there is a need in the art for a pre-engineered prefabricated
enclosure, for
use with solid phase thermal energy storage media that is economical, of
adequate strength,
highly thermally insulated, able to withstand the exposure temperatures to
which it is subjected,
and with the required thermal storage capacity and means of heat transfer,
such as
appropriately configured heat transfer coils of electrical wiring or piping
design, with all
components in a form that can be readily assembled by persons without
specialized knowledge
of the process and material characteristics required in the construction of
said enclosure and
ancillaries. Said heat transfer coils should be in a form suitable for
connection to standard state
of the art energy recovery systems, such as solar-based or electric, with the
latter typically being
in conjunction with an off-peak generation purchase agreement.
The enclosure should be of a design that can be varied in size to cover a
range of
thermal energy storage capacities and applications. The enclosure should be
adaptable to
either interior or exterior installations, with the latter being in a form
suitable for mounting of
solar collectors on the roof of said enclosure if advantageous in a solar-
based system, and also
one that satisfies the aesthetic requirements of the installation. This latter
consideration, namely
aesthetics, can be significant in establishing an embodiment of the thermal
energy storage
enclosure as the preferred alternative in an outside setting to other energy-
saving and/or cost-
saving options that may be available, but that may not offer as great an
economic advantage
through reduced energy costs.
SUMMARY OF THE INVENTION
As an aspect of the present invention, there is provided a prefabricated or
kit enclosure
for storing thermal energy comprising: an enclosure four walls, a top, and a
bottom; at least one
thermal energy storage medium contained in the enclosure; an input means for
transferring
thermal energy into the at least one thermal energy storage medium; and an
output means for
transferring thermal energy out of the at least one thermal energy storage
medium, the walls,
the top, and the bottom of the enclosure comprise at least three layers, an
inner layer for
providing structural support for containing the at least one thermal energy
storage medium, an
outer layer for providing structural support, and a middle layer for providing
insulation for the
thermal energy stored in the at least one thermal energy storage medium, and
the at least three
layers being bonded together with an adhesive to act compositely to form a
structural insulated
panel.
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The present invention is a prefabricated insulated enclosure for the storage
of thermal
energy in solid phase particulate storage medium or media (PTESM) at
temperatures up to
125 C and possibly higher, that provides a practical alternative to a single
or multiple water
storage tank(s) typically used for this application, such as in solar-heated
DHW and space
heating installations, and also as an alternative to other methods and
enclosures that utilize a
solid phase storage medium, but that lack the innovations and advantages
featured in the
current invention. The PTESM used to fill the enclosure can be sand, gravel,
or other powder or
granulated material, or, as described later in this section, a combination of
particulate media
grades, with the different grades separated by a cylindrical metallic
structural partition, thereby
benefiting the heat transfer processes involved due to specific properties
characteristic of each
grade as discussed herinafter. In addition, it is also possible to incorporate
PCMs as a portion of
the PTESM used, thereby benefiting from latent heat capacity of the PCMs in
addition to the
sensible heat capacity of the PTESM. The inventive enclosure is adaptable to
both interior
installations, and exterior installations with appropriate weather protection
elements added to
the enclosure as further described hereinafter.
The inventive enclosure is constructed of a set of panel-type envelope
components
forming the two side walls, two end walls, roof and floor. Said envelope panel
components are
designed as prefabricated composite "sandwich" type assemblies with rigid
facing panels and a
core of sheet or board-type insulation, or alternately, a foamed-in-place type
of insulation. In one
embodiment of the current invention, these components are bonded to each other
to act
compositely in providing flexural and shear strength in resisting the lateral
loading imposed on
the walls by the PTESM, as well as gravity loading, both due to the weight of
the PTESM and
other interior components as further described hereinafter, and also of
external environmental
loading in the instances of exterior installations of the inventive enclosure.
Said external
environmental loadings are discussed further hereinafter. This design concept
for said
embodiment of the sandwich panel is similar to that employed in structural
insulated panels,
commonly known as SIPs, as used in the exterior envelope construction of some
buildings.
The aforementioned sandwich panel envelope components have the thermal
insulative
resistance required to restrict heat loss from the PTESM to acceptable values,
as determined
through economic analyses that generally consider the following; cost savings
through reduced
purchase requirements of conventional energy, enclosure and system
construction and
installation costs, and calculated rates of thermal energy loss through
enclosure envelope
components. Maximum anticipated exposure temperature from contact with the
heated PTESM
impacts on the aforementioned materials used for said sandwich panel
construction, namely,
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the interior facing panels, combination structural and insulative core, and
bonding adhesive(s).
Given that the panels for the inventive enclosure combine the structural
characteristics of the
aforementioned SIP panels along with a high temperature resistance
necessitated by the
relatively high temperature potentially attainable in the storage medium, the
said panels for the
inventive enclosure shall hereinafter be referred to as HTSIP ("high
temperature structural
insulated panel") as an abbreviated form of identification.
In a second embodiment of this invention the flexural and shear strength
requirements of
the wall sections of the insulative enclosure are provided by external
structural framing against
which the sandwich wall panels are braced. Similarly, the floor panel can be
provided with
additional structural support in the form of a prefabricated but conventional
floor framing
assembly, or alternately, a base slab, typically of concrete construction.
Depending on the
height of wall, span of the floor, and weight and lateral loading
characteristics of the PTESM, it
may not otherwise be economically practical to provide the strength required
to the floor as in an
HTSIP type assembly. In these cases the non-structural sandwich panels shall
hereinafter be
referred to as HTSANIP ("high temperature sandwich insulated panel") as an
abbreviated form
of identification.
In another embodiment of the invention the insulative core of said sandwich
panels are
constructed of multiple bonded layers of different insulative materials such
that adequate
structural and thermal performance is provided by the core in achieving the
required structural
performance of said sandwich panels. Less costly materials can then be used
where maximum
temperature resistance requirements through the thickness of said insulative
core are reduced
as a result of the temperature gradient that naturally occurs through the
sandwich panel
assemblies with increasing distance from the aforementioned and heated PTESM
In yet another embodiment of the current invention additional sandwich panel
layered
components, comprising a high temperature insulative layer and high
temperature protective
liner panel in contact with the PTESM, are bonded to the prefabricated
insulated sandwich
panel assemblies of the walls, floor and roof of the enclosure, thereby
providing added
protection against deterioration in the structural and/or thermal performance
of the sandwich
panel assemblies as a result of the aforementioned temperature gradient, and
thus avoiding
similar deterioration in the structural and/or thermal performance of the
enclosure as a whole
assembly.
In yet another embodiment of the current invention the enclosure is provided
with two
separate prefabricated internal heat transfer systems, with the "input" system
consisting of one
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or more heat transfer coils to transfer the thermal energy from the energy
source to the PTESM
in the inventive enclosure, and the "output" system consisting of one or more
heat transfer coils
to transfer said stored energy to the end use application, or in some cases to
one or more
intermediate energy transfer devices, such as an inside water tank with
relatively small thermal
storage capacity in comparison to the inventive enclosure.
Said "input" heat transfer systems can be one of a range of alternative
designs, namely
in the form of piping for containment of liquid as the heat transfer medium,
ducting for
containment of hot air as the heat transfer medium, or electric resistance
wiring. Said "output"
heat transfer systems are generally in the form of piping for containment of
liquid as the heat
transfer medium. Where the heat transfer system type is in the form of piping,
external fins
attached to said piping may be provided to improve the efficiency of energy
transfer to or from
the PTESM. Configuration and construction of these heat transfer system
elements are
designed to facilitate the placement of the PTESM with minimal risk of damage
to said elements
during the process of filling the inventive enclosure with said medium
(media), and also to
preferentially transfer heat from storage areas of higher temperature of said
medium (media)
within the inventive enclosure rather than from storage areas of lower
temperature of said
medium (media). In one embodiment of the invention the aforementioned
prefabricated
structural sandwich panel assemblies are provided with insulative sleeves (16)
at the locations
where the aforementioned piping, wiring, and ducting of the associated
aforementioned thermal
energy transfer device(s) penetrate said sandwich panels, thus providing
protection to portions
of the insulative core that may otherwise be damaged if exposed to direct
contact with the
heated inlets and outlets of the heat transfer devices.
In another embodiment of the invention the enclosure is provided with one or
more
heretofore identified cylindrical metallic fabrication(s) extending vertically
between the interior
faces of the floor and roof sandwich panels of the inventive enclosure to
allow separation of
different PTESM grades, thereby providing additional benefits as summarized
below;
The separation of PTESM grades as noted better optimizes the use of the
different
performance characteristics of the storage media both inside and outside the
barrier created by said cylindrical fabrication(s). A preferred grade of PTESM
for
placement inside the confines of said cylindrical fabrication(s) is one such
that a
balance is provided in the cost of the medium and in reducing the potential
for
damage to the heat transfer coils positioned within said fabrication(s) during
the
PTESM filling process, or during the removal of the PTESM in the event
servicing
of said coils is required, while still providing adequate heat transfer
capabilities,
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confines of said cylindrical fabrication(s) is one, different from the
aforementioned
"inside" grade, such that a balance is provided in the cost of the medium and
in
maximizing both heat transfer efficiency and thermal energy storage capacity,
such as with gravel.
Servicing and removal of the heat transfer coils positioned within said
cylindrical
fabrication(s) is facilitated through the ability to remove just the PTESM
material
within said fabrication(s) by suction or other process, and leaving
undisturbed the
PTESM material occupying the space between said cylindrical fabrication(s) and
the inside faces of the enclosure.
In another embodiment of the invention the enclosure is provided with conduit
propitiously positioned within the interior space to accommodate wiring and
temperature sensor
devices for the purpose of recording process data and providing data to the
process control
system employed in managing the heat transfer processes involved.
The inventive enclosure can be pre-assembled, or made available in kit form,
with the
previously described HTSIP and/or HTSANIP components prefabricated for ready
assembly in a
location remote from the area of said fabrication. In various embodiments of
the invention, the
other heretofore-described ancillary components can be included in said kit.
Although the inventive enclosure is suitable for use in a variety of
environments,
including residential, institutional, commercial and industrial, the
anticipated highest demand is
in residential applications, and more specifically, in active solar heating
systems, for either DHW
heating or space heating, or both combined. In such solar heating systems, the
PTESM in the
enclosure is heated by conventional solar collectors, with temperature
regulation by a
compatible conventional control system as typically used in solar heating
systems employing
storage tanks for containment of water or other liquids as the means of
storing the thermal
energy. The PTESM is able to take greater advantage of the higher temperature
capabilities of
some designs of collectors, such as "vacuum tube-" or "evacuated tube" - type
solar collectors,
in comparison to what is practical in the storage of water in conventional hot
water storage
tanks. In addition to heating applications, the enclosure is also able to
provide thermal energy in
powering the refrigeration cycle by means of thermally-driven coolers in space
cooling systems.
A number of parameters in the design of the inventive enclosure and
aforementioned
ancillary components can be varied and thus accordingly impact thermal energy
storage
capacity and efficiency. These parameters include overall enclosure size and
thermal insulative
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resistance of the HTSIP envelope, thermal characteristics of the PTESM, and
design
specifications of the internal heat transfer coils.
In numerous applications, such as in solar-based residential combined DHW and
space
heating systems, significantly greater thermal energy storage capacity is
typically achievable
with the inventive enclosure than with traditional water tank storage. To
illustrate this point, the
theoretical thermal energy storage capacities of typical configurations in
each of the two storage
systems were calculated.
Interior measurements of the inventive enclosure were taken as 1800 mm x 2400
mm x
1800 mm for comparison to a 760 litre (200 US gal) water storage tank,
generally considered a
"large" tank for a residential system, and one more likely to be used for
combined DHW and
space heating rather than just DHW alone, a more common configuration. The
PTESM for the
inventive enclosure was assumed to be silica sand with a specific heat value
of 1,280 kJ/M3 K,
in comparison to water, with a comparable value of 4,180 kJ/M3 K. Maximum
operating
temperatures of 125 C and 90 C were assumed for the inventive enclosure and
storage tank
respectively, in consideration of the higher temperature capabilities
typically achievable with the
PTESM in the inventive enclosure. A common reference ambient temperature of 35
C was
assumed as the minimum useful temperature for heating purposes. Based on the
foregoing
parameters and including an allowance for reduced thermal storage capacity due
to the space
occupied within the inventive enclosure by heat transfer coils and other
peripherals, the
theoretical thermal energy storage capacities were determined to be 866 MJ
(240 kw-hr) and
170 MJ (47 kw-hr) for the inventive enclosure and water storage tank
respectively relative to the
base thermal energy content at the assumed common ambient temperature in the
two sample
systems as described.
Obviously the difference in thermal energy storage capacities would be even
greater for
a smaller water storage tank more typical for this application, particularly
in a residential system.
Such a difference may influence the decision regarding degree of conversion to
a more
environmentally sensitive energy system; potentially even to the extent it
could be determined
not to proceed with the conversion in the first place. As previously noted,
the size of the
inventive enclosure and associated volume of PTESM can be varied over a wide
range with
minimal increased risk resulting from the increased thermal storage
capacities, in contrast to the
situation with water storage based systems, as discussed heretofore, and
further hereinafter.
The enclosure is adaptable to either an interior or exterior site
installation. In an exterior
installation, the basic inventive enclosure structure is typically protected
from weather elements
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by means of conventional roof and wall sheathing and other conventional cover
materials. In the
case of the enclosure being constructed of HTSIP elements, as heretofore
defined, the said
enclosure also forms the base structural element in resisting the additional
imposed design
loadings of an environmental nature. Aesthetic requirements can be met in
those instances
through the selection of appropriate cover materials and trim elements,
including facade-style
window and door elements, and by tailoring the shape of the visible "building"
as desired,
thereby providing an appearance that is complementary to the site and
adjoining buildings.
An additional benefit of an exterior setting for a solar energy installation
utilizing the
inventive enclosure as noted above is that of the roof providing a convenient
and preferential
location for solar collector mounting that is more-readily accessible than is
often typically the
case, in turn allowing for improved access for inspection and maintenance of
said collectors,
along with the possibility of adjusting the orientation of said roof to
maximize the solar radiation
collection efficiency of said collectors.
The invention provides several advantages over existing hot water storage
systems in
many potential applications;
As discussed heretofore, thermal energy storage capacity can be more easily
varied over a larger range thereby increasing the potential for greater
storage for
periods of darkness and low solar radiation, thereby yielding increased
savings
through greater reductions in conventional energy costs.
The concern over liquid spillage of the storage medium is eliminated, other
than
the potential risk of a smaller amount of PCM if used as replacement for some
fraction of the PTESM. Although in those systems employing liquid-type solar
collector systems, process fluids at high temperatures still exist in the heat
transfer
piping systems and in possible auxiliary equipment, such as an optional
intermediate small energy transfer tank that can be used in the heat exchange
system serving the end-use application, the total volume of hot fluids is
significantly reduced. When the inventive system is used in conjunction with
off-
peak electrical generation, concern over liquid spillage is limited to just
that of the
circulating liquid type heat recovery system employed in the recovery of
thermal
energy from the PTESM of the inventive enclosure.
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Higher insulation levels can more easily be provided for with the inventive
enclosure in comparison to that practically achievable with conventional hot
water
storage tank installations.
The maximum temperature of the storage medium can typically be increased in
comparison to water-based storage, although it is recognized that this
advantage
is offset to some degree by the lower specific heat capacity of many potential
common medium materials, such as sand: in comparison to water.
In addition to the aforementioned advantages over alternative existing
designs, the
inventive enclosure incorporates other features that increase the practicality
of the form of
thermal energy storage it affords to many potential users of said energy as
follows:
The invention can be readily retrofitted to existing houses. As heretofore
noted, the
enclosure can be installed in either an interior or exterior setting. In
further
variations of site selection options, it can be located inside an existing or
proposed
building that is outside the main residence, such as a detached garage
structure,
with the connective piping to the end use structure typically insulated and
routed
through burial in a trench or in some other effective manner.
The enclosure can accommodate a range of PTESM materials. Sand and gravel
are considered the most economical relative to initial cost, however other
materials
may prove to be more cost effective taking into consideration thermal capacity
and
alternative energy costs. As previously noted one alternative to further
increase
storage capacity for a given enclosure is in the use of PCMs as a replacement
fraction of the PTESM mass.
The prefabricated nature of the construction, including the integral and
appropriately-
configured heat transfer system assemblies, utilizing materials specifically
selected to meet
necessary thermal, structural, and aesthetic requirements, along with the
other advantages
afforded by the inventive enclosure, as heretofore outlined, in satisfying the
energy demands of
the heating and/or cooling system(s) of the end use application are considered
key elements in
the novelty of the invention. The enclosure system thus has considerably
greater practicality,
including economic viability, for construction by the typical end-user, either
with assistance from
a contractor, or as a "do it yourself project, than the alternative of
attempting to construct a
system utilizing similar concepts but without the benefit of the engineering
design or
prefabrication of required components
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= . =
Other advantages and features of the invention will become more apparent from
the
following description and the accompanying drawings which are illustrative of
preferred
embodiments of the invention claimed herein.
BRIEF DESCRIPTION OF THE DRAWINGS
Drawings which illustrate embodiments of the invention and included herein are
as
follows;
Figure 1 is a sectional view taken at a vertical plane through the basic
embodiment of
the invention with a single grade of core insulation and depicting heretofore
described "input"
heat transfer coil and "output" heat transfer coil in schematic form along
with the insulative
sleeves of the penetrations of the supply and return piping for said heat
transfer coils where
penetrating the HTS1P or HTSANIP of the enclosure wall.
Figure 2 is a sectional view taken at a horizontal plane through another
embodiment of
the current invention with a dual grade of core insulation in the heretofore
described HHTSIP,
and depicting heretofore described "input" and "output" heat transfer coils in
schematic form,
with the heretofore described metallic cylindrical fabrication and two
different and isolated
grades of PTESM.
Figure 3 is a sectional view through the same embodiment of the current
invention as in
Figure 2 above but with the view taken at a vertical plane through the
invention.
Figure 4 is a sectional view through an abutting corner of vertical and
horizontal HHTSIP
panels illustrating the dual grade nature of core insulations, and the thermal
break detail
heretofore described at said corner.
Figure 5 is a sectional view at the junction of connecting side edges of
abutting HHTSIP
panels illustrating the thermal break detail heretofore described at said
junction, and also
depicting the embodiment of said panel where two grades of insulation are
bonded to form a
structural core such that adequate structural and thermal performance is
provided by the core in
achieving the required structural performance of said sandwich panels as a
whole, but
permitting less costly insulative material to be used where maximum
temperature resistance
requirements through the thickness of said insulative core are reduced as
heretofore described.
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= .
Figure 6 is a sectional view taken at a vertical plane through an embodiment
of the
current invention as in Figure 3 above but depicting the installation in an
exterior location with
weatherproofing additions to the inventive enclosure, and in this embodiment
depicting separate
external structural floor support as heretofore described as a possible
preferred or required
element.
Figure 7 is an elevation view depicting the installation of the inventive
enclosure in an
exterior location as in Figure 6 but with the inventive enclosure hidden by
standard "outbuilding"
type features such as wall siding, roof structure and facade style window and
door elements, in
satisfying additional aesthetic preferences, in addition to contributing to
the weather resistant
functionality of said building.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The basic embodiment of the previously-defined HTSIP assembly as illustrated
in Figure
1 consists of a minimum of three layers, namely an outside facing panel (1), a
middle insulative
core (2), and an interior liner panel (3). The layers are bonded together with
adhesive (4) with
the strength required to allow the layered assembly to act compositely in
resisting the imposed
structural loadings as heretofore described. In another embodiment of the
current invention the
insulative core is self-bonding to the facing panels, as in the case of a
foamed-in-place
polyurethane grade insulation, and said adhesive is thereby not required. It
is critical that the
composite assembly maintains adequate strength at the maximum exposure
temperatures
anticipated at each interface and depth throughout the thickness of the
assembly. The most
severe (ie highest) exposure temperature occurs at the interface of the PTESM
and the interior
liner panel (3), and decreases through the thickness of the various layers in
the HTSIPs of the
inventive enclosure to a minimum at the exterior surface of the outside facing
(1).
The interior facing (3) can be a rigid panel such as fiber-reinforced cement
board, or
other panel product with adequate strength properties at the higher
temperatures anticipated
from exposure to the heated PTESM. The insulating core (2) can be one of a
variety of products
that provides the desired combination of mechanical and insulative properties
at the maximum
design operating temperature, such as polyisocyanurate foam and cellular glass
rigid
insulations. The exterior facing (1) can be a rigid panel such as plywood, or
other engineered
wood product, fiber-reinforced cement board, or Other similar product with
adequate mechanical
properties. This embodiment of the HTSIP shall hereinafter be identified as
the basic HTSIP.
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CA 02789343 2013-10-04
In one embodiment of the current invention, per figures 2 - 6, where dictated
by the
maximum operating temperature in the PTESM, the basic HTSIP assembly described
above (1,
2, 3, 4) is provided with additional protection against said temperature
consisting of an
additional layer of high-temperature-resistant insulation (5), such as
cellular glass or mineral
fiber type and a separate high temperature liner panel (6) in direct contact
with the PTESM (19).
These additional layers are bonded together with suitable high temperature
adhesive (7), and to
the internal facing panel of said basic HTSIP with heretofore described
adhesive (4). In this
embodiment of the current invention it is possible that the rigid structural
panel thereby
positioned in the interior of the sandwich panel assembly (3), and provided
with the additional
thermal protection heretofore described, can in some cases be a wood-based
product such as
plywood or OSB whereby required strength properties are maintained at the
maximum
anticipated operating temperature at that location in the assembly. As
heretofore noted, it is also
possible that depending on the temperature gradient through the thickness of
said embodiment
of the sandwich panel assembly, a polystyrene or other grade of insulation
with lower maximum
operating temperature capability but also less costly grade can be used as the
structural core
element (2), or as the outer layer (2b) in a bonded multi-layer structural
core in the heretofore
described HTSIP assembly and contributing to the strength requirements of said
panel. This
bonded multi-layer structural core (2a, 2b) is illustrated in the embodiment
depicted in Figure 5.
This structural sandwich panel assembly with even higher temperature
resistance then
becomes another embodiment of the HTSIP assembly, and is hereinafter
identified as HHTSIP
(Higher High Temperature SIP).
The panels are connected along their edges using structural angle sections (8)
predrilled
at pre-determined spacings and fastened to adjoining panels along their edges
with
conventional screw type fasteners (9) of the design size and strength required
to resist the
loading imposed by the PTESM. In some embodiments of the current invention a
wood spacer
(10) is installed along the edges of the panel assembly to further stabilize
this connection when
required
An important feature of the edge detail of.the HTSIP assembly, as shown by
Figure 1, is
that the edge of the foam core is shaped (11) to minimize thermal bridging
through the thickness
of the panel assemblies in this connecting corner region of abutting panels of
the inventive
enclosure. As further security in maintaining this thermal break and guarding
against thermal
energy loss at said connecting areas, a strip of high temperature blanket-type
insulation (12) in
the range of 3 mm thick is inserted in said corner region during the assembly
process of the
inventive enclosure.
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CA 02789343 2013-10-04
. -
Similar to the low thermal bridging objective of the HTSIP assembly detail
referenced
above, a thermal break is also incorporated in the HHTSIP assembly (1 lb) as
illustrated in
Figure 4 in the layer of high-temperature insulation (5) as a means of
reducing the maximum
temperature exposure to the basic HTSIP assembly component of the HHTSIP
assembly
heretofore described.
In addition to the construction measures adopted at connecting comer regions
heretofore described, in some embodiments of the inventive enclosure, as
illustrated in Figures
1 and 4, the outer panel facing (lb) of the horizontal roof HTSIP or HHTSIP is
extended beyond
the outermost contact edge of the outer vertical panel facing of the side wall
(1), with said
extension (lc) being in the range of 10 mm. In these embodiments, a horizontal
spacer strip
(13), typically of wood or plastic material, is installed against the top and
bottom edges of the
vertical HTSIPs and secured by the aforementioned structural angle sections
(8) and attendant
securing fasteners (9) to maintain the necessary relative positioning of the
roof and floor panels
with the vertical wall panels of the inventive enclosure. These design details
aid in the
assurance of full load bearing in the transmittal of gravity loading through
the roof panel (lb) to
said vertical panels of the inventive enclosure. The security of this load
transfer detail becomes
even more critical when the inventive enclosure is installed outdoors, with
said enclosure
providing the structural support in resisting additional loading to that of a
typical indoor
installation, namely the dead loads of the external roof construction and any
solar collector units
and associated framing mounted on said roof, and live loads imposed by snow
and wind as
pertinent to the geographic region of the enclosure installation.
Where the size of the inventive enclosure is such that multiple HTSIP or
HHTSIP panels
are required for one or more sets of opposite faces of the enclosure, an edge
detail (11a) similar
to that of Figure 5 is provided to minimize thermal bridging through
connecting side edges of
abutting panels. As heretofore noted in the case of the comer edge junctures
of the inventive
enclosure, a strip of high temperature blanket type insulation (12a) in the
range of 3 mm thick is
also inserted in the joint of said connecting side edges as added insurance
against thermal
bridging.
As heretofore noted, in one embodiment of the current invention, the flexural
and shear
strength requirements of the HTSANIP wall sections of the inventive enclosure
are provided by
extarnal structural framing (13a) against which the sandwich wall panels are
braced, as
illustrated in Figure 3. Said framing can be conventional construction, as in
the use of lumber
components, with the loading from the inventive enclosure transferred from
said sandwich wall
CA 02789343 2013-10-04
=
panels by some standard structural element as a filler panel (13b) possessing
sufficient
compressive rigidity.
In one embodiment of the current invention input and output heat transfer
coils (14, 15)
are selectively positioned and spaced to optimize heat transfer into and from
the PTESM. In the
embodiments shown in Figures 1, 2, 3 and 6, said heat transfer coils are shown
schematically
as coiled piping, however the input heat transfer coil(s) (14) can alternately
be ductwork or
electric resistance wiring as heretofore noted. Said heat transfer coil
piping, ductwork or electric
resistance wiring penetrate the inventive enclosure walls in heretofore
described insulative
sleeves (16) terminating at ends (14a) for input heat transfer coil(s) and
ends (15a) for output
heat transfer coil(s), with said terminations suitable for connection to the
process system
services external to the inventive enclosure. Said insulative sleeves (16)
serve to minimize heat
loss from the inventive enclosure, and as with the HTSIP or HHTSIP assembly
previously
described, thereby maintain adequate performance at the maximum design
exposure
temperature anticipated.
As heretofore noted in this section, in one embodiment of the current
invention one or
more metallic cylindrical fabrication(s) (17) is provided to allow the use of
two separate grades
of PTESM, typically a finer grade, such as sand (18), within the boundary of
said fabrication(s),
and a coarser grade, such as gravel (19), outside the boundary of said
fabrication(s).
In another embodiment of this invention, one or more roof HTSIP or HHTSIP
assembly(ies) is designed to be removable to facilitate access to the
aforementioned heat
transfer coils for servicing without the dismantling of the entire inventive
enclosure thereby
minimizing the amount of PTESM to be removed. In this case the adjacent roof
and wall HTSIPs
or HHTSIPs that remain in position adjacent to the temporarily removed
panel(s), and reinforced
as required, provide the necessary stiffness and strength in maintaining the
overall dimensions
and structural integrity of the enclosure under the applied loadings that
remain during said
servicing procedure.
In another embodiment of the current invention, heretofore mentioned conduits
(20) are
positioned within the enclosure to accommodate wiring and enable the secure
embedment of
temperature sensor devices within the PTESM (18, 19) and within the insulative
layers of the
envelope of the inventive enclosure itself (2, 5) if desired, for the purpose
of recording operating
data and providing data to the process control system that manages the heat
transfer processes
involved. Fittings (21) are installed in said conduit at the embedment
locations for said sensors,
as shown in Figures 3 and 6. Said conduits penetrate the walls of the
inventive enclosure in
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CA 02789343 2013-10-04
insulative sleeves similar to those heretofore described for heat transfer
device enclosure wall
penetrations (16), with end terminations (20a) compatible with exterior data
collection and
control system wiring.
As heretofore indicated, when installed outside, the inventive enclosure is
protected from
the environmental elements by a weather resistant envelope, consisting of a
roof structure (22),
siding and associated strapping (23), and with windows (24) and doors (25) of
a facade nature,
all contributing to the presentation of desired appearance in the form of a
site-compatible
"outbuilding" as illustrated in Figures 6 and 7. In the embodiment depicted in
said figures a
separate extemal structural floor support frame (26) as heretofore described
is depicted in place
under the HHTSANIP floor panel assembly. Where the energy source is solar,
exposed roof
space thus provided can serve as a preferred area for mounting of solar
collectors (27). The
roof structure in such construction can be made asymmetrical as shown
schematically in said
figures to preferentially increase space available to said collectors in a
solar heating system.
Maximizing solar exposure for said collectors can thereby be achieved through
combination of
this expanded roof surface and the selective orientation of said roof surface.
In this embodiment
the inventive enclosure is designed as the structural core of the structure in
withstanding the
additional environmental loadings imposed in an exterior setting, as a means
of eliminating the
need for additional structural elements and their associated costs, thus
contributing to the
economic viability of the inventive enclosure-based energy storage system. As
heretofore noted,
other embodiments of the current invention achieving similar functionality of
the energy storage
process are achievable using HTSANIP panels in which exterior structural
framing is employed
to resist the interior loading imposed by the PTESM and also exterior loading
on the structure
from environmental effects.
As will be apparent to those skilled in the art in light of the foregoing
disclosure, many
modifications to the invention described herein are possible without departing
from the spirit and
scope thereof. Accordingly, the scope of the current invention is to be
construed in accordance
with the substance of the claims as defined in that section of the current
application.
Construction of the inventive HTSIP and HTSANIP enclosure panels as heretofore
described is accomplished using methods essentially as employed in the
construction of
sandwich panels, including structural insulated panels, such as are typically
used in the
envelope construction of some buildings. These methods include assembly of the
sandwich
panel layers, including the insulative core sheet(s) and facings, and
typically either using
adhesives and possibly heat in joining said components under pressure, or in
the utilization of a
self-bonding grade of insulation, as in the case of a foamed-in-place urethane
grade. The
17
CA 02789343 2013-10-04
general methods employed in this process are thus well practiced and
understood, except that
the various component materials must be specifically selected for anticipated
maximum design
temperatures and loadings, and other details such as connections and
penetrations require
consideration of the end use application for the current invention. It is
significant that the
maximum design temperatures are typically greater than those encountered in
said building
envelope applications. In the case of the HHTSIP panels as heretofore noted,
the basic
procedure remains similar except that an additional insulative layer is
introduced to the
sandwich panel assembly as a means of further increasing its maximum operating
temperature
capability.
Also as heretofore noted the inventive enclosure with attendant ancillary
components
can be pre-assembled to various stages of completion, or the various
components prefabricated
in a centralized manufacturing facility suitable for final assembly in the
field.
INDUSTRIAL APPLICABILITY
As heretofore noted, the inventive enclosure and associated ancillary
components have
many potential applications where thermal energy is required, whether that be
in residential,
commercial, institutional or industrial applications. It is anticipated
however that the most widely
targeted application will be for space heating systems and DH W heating
systems in single- and
multi-residential, institutional and light commercial situations and also for
heating the water of
swimming pools and similar facilities. Also as noted heretofore, the energy
source most widely
anticipated to be utilized with the inventive enclosure applications is solar,
although said
enclosure is also suitable for use in storage of thermal energy from an
electrical source,
generally in off-peak generation / time-of-use applications. In addition
however the thermal
energy retained in the enclosure can also be used in powering the
refrigeration cycle by means
of thermally-driven coolers in space cooling systems.
=
18
