Note: Descriptions are shown in the official language in which they were submitted.
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TILE SYSTEMS WITH ENHANCED THERMAL PROPERTIES AND
METHODS OF MAKING AND USING SAME
CROSS-REFERENCE TO RELATED APPLICATION
The present application claims the benefit of United States Provisional Patent
Application
Serial Number 61/177,224 filed 11 May 2009, and entitled "Tile Systems with
Enhanced
Thermal Properties and Methods of Making and Using Same," which is hereby
incorporated by
reference in its entirety as if fully set forth below.
TECHNICAL FIELD
The various embodiments of the present invention relate generally to tile
systems. More
particularly, the various embodiments of the invention relate to tile systems
with improved
thermal performance and to methods of making and using such tile systems.
BACKGROUND
Ceramic tiles are prized for their aesthetic and wear-resistant properties for
applications
such as floor and wall coverings. One disadvantage that ceramic tiles have
relative to other
decorative covering materials (e.g., solid wood, plastic laminates, and
carpeting) is that surfaces
covered with ceramic tiles tend to feel colder. During winter months, interior
spaces are actively
heated, and the significant temperature difference between outside and inside
drives the heat loss
through the floor and walls. There is a need to reduce the heat lost through
the floor and walls
by increasing the thermal insulating ability of ceramic tile products.
Often there is the desire to warm floors by installing radiant heating systems
underneath
the flooring; and, if the flooring is to be actively heated, then ceramic tile
is often preferred due
to its superior ability to conduct heat to its upper surface, where the heat
can be used to heat the
room and its occupants via radiative, convective, and conductive means.
Thermal energy from a
floor heating system flows away from the heating elements in all directions.
Heat transferred up
through the flooring is used for heating, while heat flowing towards the sub-
floor is lost. The
overall system efficiency will be at least partly determined by the relative
rates of heat transfer
towards and away from the floor's top surface. As such, in addition to
reducing heat lost to the
sub-floor, there is a need to increase the ability of ceramic tile to conduct
heat from heating
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elements towards the room. Additionally, whether the floor is directly heated
or not, the sub-
floor and foundation act as a heat sink, and so the overall system efficiency
can be increased if
the flooring is constructed to prevent or reduce heat loss to the sub-floor.
As was described
above for floors, heating systems also can be installed either onto walls or
as a part of the wall,
and the desire to improve the flow of heat into the space adjacent to the wall
outer surface while
also reducing the loss of heat in the opposite direction is governed by the
same considerations.
Accordingly, there is a need for tile systems having improved thermal
properties. It is to
the provision of such systems, and the associated methods of manufacture and
use that the
various embodiments of the present invention are directed.
BRIEF SUMMARY
Various embodiments of the present invention are directed to improved floor
and wall tile
systems with enhanced thermal properties. The tile systems provide enhanced
thermal properties
to floor and wall coverings. The improved tile systems, which can be
implemented in either
heated or unheated applications, generally include a tile and a phase change
material (PCM).
The PCMs can provide heat capacity via sensible and latent heat storage
methods.
According to some embodiments, a tile system includes a tile and a PCM that is
in
thermal communication with the tile. The PCM does not comprise a portion of
the tile, and is
configured to increase the heat capacity of the tile system. The tile system
can also include an
optional heating element in thermal communication with the PCM and/or a
thermally insulating
layer disposed between the tile and a surface of a floor or wall on which the
tile system is
disposed.
In some cases, the PCM is a solid state PCM. In other cases, it is a liquid
PCM
encapsulated in a thermally conductive container (e.g., a metal container).
Similarly, in some
situations, the tile is a ceramic tile.
The PCM can be positioned in a variety of locations. For example, the PCM can
be
disposed in a cavity within a backside surface of the tile. It can also be
disposed directly on a
backside surface of the tile.
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In some embodiments, the tile comprises a portion of a floating floor or wall
tile unit.
Such a tile unit can include a substrate, such that the tile is disposed on,
or within a cavity within,
the substrate. In these situations, in addition to the above-described
locations, the PCM can be
disposed: between a backside surface of the tile and a top surface of the
substrate; at least
partially within a cavity within a top surface of the substrate; entirely
within the substrate (e.g.,
when the PCM comprises a portion of the substrate); on, or within a cavity
within, a backside
surface of the substrate; or a combination of one or more of the foregoing
locations.
According to some embodiments of the present invention, a tile system can
include a tile
unit that includes a substrate and a tile that is disposed on, or within a
cavity within, the
substrate; and a PCM in thermal communication with the tile. The PCM does not
comprise a
portion of the tile, and it is configured to increase the heat capacity of the
tile system. The PCM
can be disposed in a cavity within a backside surface of the tile, directly on
the backside surface
of the tile, between the backside surface of the tile and a top surface of the
substrate, at least
partially within a cavity within the top surface of the substrate, entirely
within the substrate, on a
backside surface of the substrate, within a cavity within the backside surface
of the substrate, or a
combination comprising at least one of the foregoing.
The tile system can also include a heating element in thermal communication
with the
phase change material and/or a thermally insulating layer disposed between the
tile unit and a
surface of a floor or wall on which the tile unit is disposed. In certain
situations, the thermally
insulating material can be located below the heating element, while the tile
is located above the
heating element and the PCM can be between the tile and thermally insulating
material.
In some implementations, the substrate can have a thermally conductive element
that is in
thermal communication with the PCM and the tile. In this manner, the thermally
conductive
element can facilitate heat transfer between the PCM and the tile.
Other embodiments are directed to methods of making the tile systems. The
improved
tile systems can be readily manufactured, having both a modest manufacturing
cost and a
relatively non-complicated geometry and construction.
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Still other embodiments are directed to methods of using the tile systems. The
tile
systems can be installed using techniques that are either standard in the
traditional tile industry
or, for groutless tile products, an easier alternative that allows a do-it-
yourself installation. The
tile systems provide for relatively simple installation of tile surfaces
having both the enhanced
thermal properties, which are not normally found in tile systems.
Other aspects and features of embodiments of the present invention will become
apparent
to those of ordinary skill in the art, upon reviewing the following detailed
description in
conjunction with the accompanying figures.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 includes schematic illustrations of (a) the backside of a conventional
high-
temperature ceramic tile, and (b) a cross-sectional side-view of the same tile
with a phase change
material (PCM) disposed in certain cavities on the posterior of the tile
according to some
embodiments of the present invention.
Fig. 2 is a schematic illustration of a groutless ceramic floor tile according
to some
embodiments of the present invention.
Fig. 3a is a schematic plan-view illustration of the underside of a groutless
ceramic floor
tile wherein PCMs are disposed within the cavities within the underside of the
substrate
according to some embodiments of the present invention.
Fig. 3b is a schematic illustration of a cross-sectional side-view of a
groutless ceramic
floor tile wherein PCMs are disposed within the cavities within the topside
surface of the
substrate according to some embodiments of the present invention.
Fig. 4 includes schematic illustrations of the underside of a groutless
ceramic floor tile
wherein PCMs are disposed (a) directly on the underside surface of the
substrate and (b) within a
cavity within the underside of the substrate according to some embodiments of
the present
invention.
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Fig. 5 is a schematic illustration of a groutless ceramic tile floor system
with two
groutless tiles mated together, wherein the PCMs are disposed between the
ceramic tile
decorative component and the substrate according to some embodiments of the
present
invention.
Fig. 6 is a schematic illustration of a groutless ceramic tile floor system
with two
groutless tiles mated together, wherein the PCMs are positioned in defined
cavities in the
substrate itself according to some embodiments of the present invention.
Fig. 7 is a schematic illustration of a groutless ceramic tile floor system
with two
groutless tiles mated together, wherein the PCMs are incorporated into the
polymeric frame itself
as an additive according to some embodiments of the present invention.
Fig. 8 is a schematic illustration of a groutless ceramic tile floor system
with two
groutless tiles mated together, wherein the PCMs are positioned onto the
backside of the
polymeric frame according to some embodiments of the present invention.
Fig. 9 is a schematic illustration of (a) a side cross-section, (b) a bottom
view, and (c) a
top view of a groutless wall tile unit according to some embodiments of the
present invention.
Fig. 10 is a schematic illustration of (a) rear view and (b) a top view of an
installed
groutless wall tile system according to some embodiments of the present
invention.
DETAILED DESCRIPTION
Referring now to the figures, wherein like reference numerals represent like
parts
throughout the several views, exemplary embodiments of the present invention
will be described
in detail. Throughout this description, various components may be identified
having specific
values or parameters, however, these items are provided as exemplary
embodiments. Indeed, the
exemplary embodiments do not limit the various aspects and concepts of the
present invention as
many comparable parameters, sizes, ranges, and/or values may be implemented.
The terms
"first," "second," and the like, "primary," "secondary," and the like, do not
denote any order,
quantity, or importance, but rather are used to distinguish one element from
another. Further, the
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terms "a," "an," and "the" do not denote a limitation of quantity, but rather
denote the presence
of "at least one" of the referenced item.
Disclosed herein are improved tile systems and methods of making and using the
tile
systems. For either heated or unheated, floor or wall applications, the
improved tile systems
described herein provide increased efficiency of heating and/or cooling a
building by enhancing
the ability of tiles to store and release thermal energy, thereby minimizing
the dynamic
temperature differences that normally develop and are the driving force behind
unwanted heating
or heat loss. Further, the methods used to obtain these advantages are
consistent with established
manufacturing and installation processes considered normal for tiles and other
flooring or wall
decor. The various embodiments of the present invention allow for products
having thermally
enhanced properties without the deleterious effects on other, normally desired
properties, namely
wear resistance, appearance, and ease of installation.
Heat transfers from a hotter region or object to a cooler region or object,
and the transfer
of heat over time (i.e., the "rate") is determined by the temperature
difference between the "hot"
and "cold" objects (i.e., the "temperature gradient") and the radiative,
convective, and
conductive thermal properties of the objects of interest. For buildings,
significant amounts of
heat are lost via radiation; particularly through windows and roofs. Buildings
in colder climates
are normally well-insulated to reduce the conductive, convective, and
radiative transfer of
building heat from the interior walls to the exterior surfaces. Heat can also
be lost from a
building through the floor, where it passes through the sub-floor and into the
foundation; or heat
can be lost through the wall, where the heat is lost to radiative or
convective transfer from the
external wall. The costs associated with heating and cooling a building can be
reduced if the
transfer of heat can be reduced and/or the temperature gradient between
conditioned spaces and
their immediate surroundings (e.g. floor, walls, and ceiling) can be reduced.
To achieve this goal, the tile systems disclosed herein generally include a
(i.e., at least
one) tile and a phase change material (PCM) that does not comprise a portion
of the tile itself.
The tile can be any type of tile, including a ceramic tile, marble tile,
granite tile, quartz tile,
natural stone tile, porcelain tile, glass tile, a variety of metal or polymer
tiles, wood plank,
laminate floor tile (i.e., floating floor unit), and the like. In addition,
the tiles can be
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conventional (i.e., non-floating) floor or wall tiles, or they can be
incorporated into a floating
floor or wall tile system, as will be described in more detail below.
For convenience, and not by way of limitation, reference will now be made to
ceramic
tiles. It should be recognized by those skilled in the art to which this
disclosure pertains that
other types of tile, such as those listed above, can be used in place of
ceramic tiles in the
embodiments described below.
Table 1 provides the thermal properties of traditional ceramic tiles compared
with other
flooring and wall material types. Relative to most other building and
construction materials
(e.g., wall board, insulation, wood paneling, carpeting, laminated flooring,
polymers, and the
like), ceramic tiles generally exhibit a higher rate of heat conduction (i.e.,
"thermal
conductivity"). In addition, ceramic tiles normally possess a higher value of
thermal effusivity, a
property that combines several material properties (heat capacity, density and
thermal
conductivity) into a single parameter. The thermal effusivity is a measure of
how quickly a
cooler object will absorb heat when placed into contact with a hotter object.
The effusivity
values in Table 1 illustrate why an unheated ceramic tile floor can "feel"
colder than a floor
made using wood, plastic laminates or carpet, because the tile can pull heat
away from the body
more quickly.
TABLE 1
Thermal Conductivity Thermal Effusivity Heat Capacity [Joules
Material
[Watts / m K] [Watts / I(s m2 K)] / Kg K]
Porcelain floor tile 1.484 1675 792
Mosaic floor tile 1.196 1453 750
Porous wall tile 0.969 1255 740
Simulated wood laminate 0.266 595 1380 *
Engineered wood laminate 0.210 542 1000 *
Polyurethane elastomer 0.255 623 1371
All measurements are for 25 C.
* - denotes the value at 25 C is extrapolated from data at slightly higher
temperatures.
Table 2 provides the range of thermal property values normally seen for
various types of
standard ceramic tile products. The limits of these property values can be
expanded somewhat
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with concerted effort. Achieving very large value increases or decreases,
however, is unlikely,
particularly for the heat capacity. Thus, methods of increasing the thermal
property values, for
example, the heat capacity, of ceramic tile products are necessary.
TABLE 2
Thermal
Thermal Effusivity Heat Capacity Density
Ceramic Tile Product Conductivity
[Watts / I(s m2
[Watts / m K] K)] [Joules / g K] (g/cc)
High Fire Porcelain 1 1.523 1703 0.802 2.376
High Fire Porcelain 2 1.484 1675 0.792 2.387
Mosaic Tile 1.196 1453 0.750 2.354
High Fire Porcelain 3 1.241 1476 0.740 2.373
Low Fire Porcelain 1 1.073 1369 0.740 2.363
Wall Tile 0.969 1255 0.740 2.195
Materials typically store heat through an increase in temperature, and the
thermal energy
stored this way is termed "sensible heat." The amount of sensible heat that
can be stored by an
object is set by its heat capacity, which is related to the material(s) of
construction as well as the
structure (e.g., porous versus highly dense). There is another heat storage
mechanism where the
storage or release of "latent heat" takes place at nearly constant temperature
when a substance
changes its physical state. An example of latent heat absorption is when a
solid melts to form a
liquid, whereas an example of latent heat evolution occurs when a liquid
solidifies to form a
solid.
PCMs store sensible heat as their temperature increases. When a specific
temperature is
reached, however, the PCM undergoes a phase transformation and can store a
relatively large
amount of latent heat. In transformations involving latent heat, the
temperature does not increase
or decrease markedly until the phase transformation is completed. Most PCMs of
interest
experience a solid-liquid phase transformation (i.e., melting). Paraffin waxes
and salt hydrates
are traditional PCMs; and, since they melt, the containment method or design,
particularly for the
corrosive salts, is a fundamental issue in employing PCMs.
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Some PCMs experience a second, solid-solid phase transformation at a
temperature
below their melting point. Although the latent heat absorbed or evolved is
normally lower than
for the solid-liquid transformation, solid state PCMs (SS-PCMs) are attractive
for some
applications because they do not require a containment method or design. To
make better use of
PCMs that melt into liquids, methods have been developed to encapsulate solid-
liquid PCMs
inside a shell of some other material that is phase and shape stable over the
temperature range of
use.
The tile systems of the present invention can make use of both liquid PCMs and
SS-
PCMs. The liquid PCMs, when used, are accompanied by a container or shell so
as to prevent
leakage or loss of the liquid PCM to the external environment. Such a
container or shell should
be made of a thermally conducting material so as to allow heat to more easily
transfer between
the PCM and the tile.
The PCMs can be incorporated in a variety of locations on, or adjacent to, the
tiles. As
stated above, in some cases, the tiles can be conventional or non-floating
tiles, which are
installed directly on a floor or wall using cementitious or resinous
fixatives. In other cases, the
tiles are incorporated into a floating tile system in which the tile itself is
indirectly installed on a
floor or wall via some intermediate substrate or base structure or structures.
The individual tile
units in a groutless tile system are composite structures having the means
necessary to effect safe
and easy installation of the tiles onto the floors or walls without using
additional fixatives or
grouting materials. Examples of floating tile systems include so-called
"groutless tile" floor or
wall systems. Groutless tile flooring systems, while briefly described below,
are described in
more detail in commonly-assigned United States Patent Application Publication
No.
2008/0184646 and International Patent Application Publication No. WO
2008/097860, which are
incorporated by reference herein in their entireties as if fully set forth
below. Similarly, while
described in brief below, groutless tile wall systems are described in more
detail in commonly-
assigned International Patent Application No. PCT/US2009/068113, which is
incorporated by
reference herein in its entirety as if fully set forth below.
In an example of a non-floating floor or wall system, the ceramic tile, which
is
manufactured with a cavity-containing back pattern, has a solid PCM or an
encapsulated liquid
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PCM disposed on its backside such that the PCM and the ceramic tile are
chemically and/or
mechanically bonded. Such a composite tile can be installed using industry
standard methods
(e.g., using an adhesive grouting material). One such composite tile shown in
Fig. 1.
Fig. la includes a schematic illustration of the backside of a conventional
high-
temperature ceramic tile, generally designated by reference numeral 100. The
backside of the
tile 100 includes hexagonal-shaped hollow spaces/regions or cavities 102. Such
patterns are
normally designed into ceramic tiles because these patterns save on material
and facilitate
several unit operations during manufacture. The pattern shown is one of many
such patterns a
ceramic tile may have on its backside that can accommodate the PCMs. In the
pattern shown in
Fig. la, for a conventional 12-inch x 12-inch ceramic tile, about 30 to about
40 milliliters (mL)
of a PCM can be placed into the about 0.7 millimeter (mm) deep cavities via a
number of
methods, and the volume capacity of the back pattern could be increased
substantially.
Fig. lb provides a schematic illustration of a side view of such a PCM-
containing
ceramic tile 100. In this illustration, the PCMs 104 are incorporated into a
portion of the
plurality of cavities 102. It should be noted that the number of cavities 102
into which the PCMs
104 are disposed can vary based on the application and the level of heat
storage desired. Thus, if
greater heat storage is desired, a larger number of PCMs 104 can be placed in
the cavities 102 of
the ceramic floor or wall tile 100. The particular location where the PCMs are
placed can be also
be tailored for the particular application.
In another non-floating floor or wall system example, the ceramic tile can
have a flat or
substantially-flat backside, such that one or more PCMs are disposed directly
on the backside
surface of the tile. A solid PCM or an encapsulated liquid PCM can be
chemically and/or
mechanically bonded to the backside surface of the tile. Just as with the
tiles with the cavity-
containing backsides, such a composite tile can be installed using industry
standard methods.
In contrast to non-floating tiles, when a groutless tile floor or wall system
is used, the
PCM can be incorporated in a number of locations. As will be described and
illustrated, the
PCM can be incorporated either: 1) in the back-pattern of the ceramic tile
(this is already
described above for non-floating tile systems); 2) in a continuous layer
between the bottom
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surface of the ceramic tile and a top layer of the groutless tile's base or
substrate layer; 3) in
cavities formed inside the groutless tile's base or substrate layer; 4) as a
filler/component of the
groutless tile's base or substrate layer; 5) in the back-pattern of the
groutless tile's base or
substrate layer; and/or 6) as one or more of the previous five situations in
combination.
For convenience, and not by way of limitation, reference will now be made to
groutless
tile floor systems where each tile is encased by a polymeric frame or
substrate to provide a so-
called "groutless tile" unit. Again, such groutless tile units and systems are
described in more
detail in commonly-assigned United States Patent Application Publication No.
2008/0184646
and International Patent Application Publication No. WO 2008/097860. In
addition to having a
ceramic tile encased by a polymeric frame, the tile units of these floor
systems generally include
mechanical joints for connecting adjacent groutless tiles.
Fig. 2 illustrates an exemplary groutless floor tile, which can be used in the
tile systems
disclosed herein. The groutless tile is generally designated by numeral 200.
The groutless tile
200 includes a durable, decorative component 202 (e.g., ceramic tile, marble
tile, granite tile,
quartz tile, natural stone tile, porcelain tile, hardwood planks, engineered
wood planks, glass tile,
a variety of metal or polymer tiles, and the like) that is disposed on a
substrate 204. The
decorative component 202 will be described as a ceramic tile in this
illustration of a tile unit for
convenience.
The decorative component 202 can be affixed to the substrate 204 using a wide
variety of
methods. The substrate 204 can be constructed of a suitable material that is
chemical resistant,
stain resistant, at least partially non-porous, and formable to within
sufficient precision. In
exemplary embodiments, the substrate 204 is formed from a polymeric material.
While the
groutless tile unit 200 is depicted as square-shaped in Fig. 2, it will be
clear that alternatively
shaped groutless tiles (e.g., circles, rectangles, diamonds, hexagons,
octagons, triangles, and the
like) are also contemplated.
The substrate 204 shown in Fig. 2, is designed to have larger dimensions than
the
decorative component 202 such that the decorative component 202 can be
disposed within a
groove defined within the substrate 204. The top surface of the decorative
component 202 and
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the top surface of the substrate 204 can form a continuous surface, if
desired. The substrate 204
includes a flange portion 206 disposed along the side edges or walls of the
substrate 204. The
flange portion 206 provides the location of a mechanical joint, which is
designed such that it is
operable for coupling together one or more adjacent groutless tiles 200. When
two or more
adjacent groutless tiles 200 are coupled using the mechanical joint of the
flange portion 206, it is
the top surfaces of the substrates 204 of the coupled tile units 200, which
are adjacent to the top
surfaces of the decorative components 202, that can provide the appearance of
a grouted finish.
Fig. 3 schematically illustrates the backside and side cross-section of one
type of design
for a groutless floor tile as shown in Fig. 2. In the backside view of Fig.
3a, the groutless tile 300
includes the substrate 304 and the decorative component 302 (of which the back
side is shown in
the cut-away circle). The substrate 304 includes the flange portions 306,
which are disposed
along the side edges or walls of the substrate 304 and are used to form the
mechanical joints to
couple adjacent groutless tiles. The substrate 304 also includes a plurality
of cavities 308. These
cavities 308, which can be formed when the substrate 304 is molded or by
removing portions of
the substrate 304 after the substrate has been manufactured, can be designed
to accommodate the
PCMs 310.
In the side cross-section of the groutless floor tile 300 shown in Fig. 3b,
the ceramic tile
decorative component 302 is disposed within a groove or channel within the
substrate 302, as
described above, with the exception that the substrate 304 has additional
cavities on the topside
surface that can provide locations for the PCMs 310. It should be noted that,
instead of (or in
addition to) placing them in cavities within the substrate 304, one or more
PCMs 310 can be
placed directly on the topside surface of the substrate such that a sandwich
is formed between the
ceramic tile decorative component 302 and the substrate 304.
To manufacture such a design, a cohesive layer or discrete portions of PCMs
310 could
be adhered to the ceramic tile component 302 or simply placed against the
ceramic tile
component 302. Next, the combined ceramic tile component 302 with the PCM 310
can be
molded around using the polymeric material that forms the substrate 304.
Alternatively, after
molding the substrate 304, the PCMs 310 can be melted and inserted into the
cavities molded
into the polymeric substrate 304.
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Fig. 4 schematically illustrates the backside of another type of design for a
groutless floor
tile as shown in Fig. 2. In the backside view of Fig. 4a, only the substrate
404 is shown. The
substrate 404 includes the flange portions 406, which are disposed along the
side edges or walls
of the substrate 404 and are used to form the mechanical joints to couple
adjacent groutless tiles.
The substrate 404 further includes a plurality of protruding legs 412, which
can be used to at
least partially support the groutless tile on the flooring surface on which it
is installed. In this
design, the PCM 410 can be disposed directly on the backside surface of the
substrate 404.
Alternatively, in the backside view of Fig. 4b, wherein only the substrate 404
is shown
again, the PCM 410 can be disposed within a cavity 408 within the backside of
the substrate 404,
similar to the design of Fig. 3a. The cavity 408 in this design (like the
cavities 308 of the design
shown in Fig. 3a can be configured to penetrate through the entire thickness
of the substrate 404
such that the PCM 410 makes direct contact to the back of the ceramic tile
decorative component
(not shown).
Thus, the cavities shown in Figs. 3 and 4 can be designed to accommodate PCMs
such
that the PCMs are directly in contact with the backside of the ceramic tile
and/or with the
thermally insulating polymer substrate between the ceramic tile and the sub-
floor. Regardless of
whether the PCMs are incorporated in the cavities on the bottom or top of the
substrate, the
mechanical integrity or strength of the composite tile structure is not
degraded. Thus, an
adequate underlying structural support is provided to the ceramic tile
component on top.
Figs. 5 through 8 provide additional views of various embodiments making use
of a
groutless floor tile system, with PCMs shown in various locations. These
illustrations all show
two groutless tiles mated together. For example, in Fig. 5, the PCMs 510 are
placed between the
ceramic tile component 502 and the substrate 504, making contact to both the
ceramic tile
component 502 and the substrate 504. In Fig. 6, the PCMs 610 are placed in
defined cavities
within the substrate 604, but do not contact the ceramic tile component 602.
In Fig. 7, the PCMs
710 are incorporated into the substrate 704 itself as an additive. Again, the
PCMs 710 of Fig. 7
do not contact the ceramic tile component 702. Finally, In Fig. 8, the PCMs
810, which do not
contact the ceramic tile component 802, are placed onto the backside of the
substrate 804.
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For convenience, and not by way of limitation, reference will now be made to
groutless
tile wall systems that comprise a tile unit, a mounting unit, a wall-fastening
device that is
configured to fasten the mounting unit to a wall, and a tile unit-fastening
device that is
configured to fasten the tile unit to the mounting unit. In general, the
mounting unit occupies a
small fraction (e.g., less than 30 percent) of an area of the wall. When the
tile unit is fastened to
the mounting unit, and the mounting unit is fastened to the wall, at least a
portion of the tile unit
does not contact the wall directly. This portion corresponds to at least the
portion that is fastened
to the mounting unit, but can include up to the entire surface of the tile
unit. Again, such
groutless tile units and systems are described in more detail in commonly-
assigned International
Patent Application No. PCT/US2009/068113.
The tile units used in these groutless wall tile systems can be designed
similar to the
groutless floor tile units. That is, these tile units can include a decorative
tile component
disposed within a groove or channel of a polymeric frame or substrate. These
tile units,
however, do not necessarily require any mechanical joints for connecting
adjacent groutless tile
units because they are held in place by the tile unit-fastening devices.
One example of such a tile unit is shown in Fig. 9. Fig. 9 includes side-, top-
, and
bottom-views of a groutless wall tile unit 900. In this illustration, the
groutless wall tile unit
includes four decorative ceramic tiles 902 disposed in a channel within a
substrate 904. The
substrate can include a recessed mounting point 918 for mating with the tile
unit-fastening device
(not shown). If the edges of the ceramic tiles 902 are not mated together,
then a sealant 912 can
be placed in the spaces between the ceramic tiles 902 in a given tile unit
900. Optionally, the
ceramic tiles 902 can be fixed into place using an adhesive or fixative 914.
Another example of a groutless wall tile system is shown in Fig. 10. Fig. 10
includes
front and rear views of an installed groutless wall tile system, wherein the
groutless wall tile
units 1000 are mounted to a wall (not shown) by means of a mounting unit 1020
that adopts a
rail-like structure. The rail-like mounting units are fixed to the wall by
means of mounting unit-
fastening devices (not shown) that can be screws, nails, bolts, or the like.
The groutless wall tile
units 1000 include a decorative ceramic tile component 1002 that is disposed
on a substrate or
platform 1004. The substrate 1004 includes tile unit-fastening devices 1018 in
the form of clips
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or hooks that can attach to the rail-like mounting unit 1020. As indicated in
the rear view of the
installed tile system of Fig. 10a, there is a gap or design space between the
surface of the ceramic
tiles 1002 of the tile units 1000 and the wall surface (which would be in
direct contact with the
backside surface of the rail-like mounting units 1020.
Just as was the case for the groutless tile floor units, the PCMs can be
placed in a variety
of locations on or within the groutless tile wall units. Specifically, the
PCMs can be placed
between the top surface of the substrate and the bottom surface of the
decorative ceramic tile
component, within cavities on the topside and/or backside of the substrate,
within the substrate as
a filler material, and/or in any cavities on the backside of the decorative
ceramic tile component
itself. In addition to these locations, when the tile system allows for it,
the PCMs can be placed
in the gap or design space between the tile units and the wall itself. In this
manner, a larger
continuous layer of a PCM can be used because there is less concern for space
than there would
be in trying to place a PCM in the substrate of a groutless tile unit.
The wall or floor tile systems that make use of so-called groutless tiles,
which do not
require cementitious or resinous grouting material for installation, confer
additional advantages
relating to the greater ease of installation as well as the ability to non-
destructively/temporarily
remove (e.g., for inspection and repair) and reinstall the tile systems. In
addition, it is possible
for the material used to form the substrates for the ceramic tiles to be
formed from one or more
distinctive materials or components that can provide specific intrinsic
thermal properties. For
example, when the substrate is formed from a polymeric (e.g., polyurethane,
polystyrene,
polyvinylchloride, or the like) foam, the substrate can confer a thermally
insulative property to
the tile behind the backside surface of the tile. This can serve to decrease
the flow of heat to or
from the space towards which the tile's decorative top surface is facing. In
another example, the
substrate can be designed to facilitate the conduction of heat between the
tile and the PCM. For
example, components comprising a thermally conductive material (e.g., metal,
graphite, or the
like) can be disposed between the ceramic tile and the PCM, thereby permitting
heat to be
transferred more readily between the ceramic tile and the PCM. Yet another
example involves
designing the substrate to have a thermally conductive material disposed
between the ceramic
tile and PCM, while a thermally insulative material is disposed around those
surfaces of the PCM
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that are not in conductive thermal contact with the ceramic tile. Such a
design can slow or
prevent the transfer of heat between the PCM and the wall or floor onto which
the tile systems
are installed, while simultaneously facilitating the conduction of heat
between the ceramic tile
and the PCM.
In some cases, the improved tile systems described herein can include a
heating element,
which is placed in thermal communication with the PCM. For non-floating wall
or floor tiles,
this heating element can be disposed between the tile and the floor or wall.
For floating wall or
floor tile systems, the heating element can be included as part of the
substrate or can be separate
from the tile unit. This optional heating element can serve to activate the
PCM by contributing
heat to the PCM, which can then transfer such heat more efficiently to the
ceramic tile. The
heating element can be controlled using known techniques used in conventional
radiant heating
systems. Such techniques would be understood by those skilled in the art to
which the various
embodiments of the present invention pertain.
The tile systems described herein can also implement an optional thermally
insulating
layer to further reduce heat loss. For example, with non-floating floor or
wall tiles, this can be a
thin fabric or foam underlayment that is placed between the ceramic tiles
(which contain PCMs
on their backside surfaces and/or within any cavities on their backside
surfaces). With floating
floors, the optional thermally insulating layer can be placed between the
substrate and the wall or
floor surface, between the PCM and the substrate surface in cases where the
PCM is placed
between the ceramic tile and the topside surface of the substrate, in the
cavities within the
backside surface of the substrate such that the PCM is between the thermally
insulating layer and
the bottom of the cavity within the substrate, and/or the like.
In certain embodiments, regardless of whether a ceramic tile or groutless tile
is used, the
ceramic tile itself may possess a chemical formula and structure such that its
intrinsic thermal
properties are enhanced relative to standard ceramic tiles.
During operation, the tile systems described herein will be able to store
latent heat or
absorb thermal energy from their environment (i.e., the "space" in which the
tile system is
installed) without as large a concomitant increase in their temperature as
would be seen in the
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absence of a PCM. As the driving force for thermal conduction, convection, or
radiation
between surfaces is the difference in temperature, the ability to obtain
thermal storage with a
reduced temperature increase leads to a reduction in unwanted heat transfers
(i.e., heat "losses").
It is these unwanted heat transfers that lead to more energy consumed in the
process of heating or
cooling a living space. Thus, the use of PCM as a passive means for improved
heat storage and
energy efficiency is effected using the tile systems described herein.
Similarly, for tile systems that also include the optional heating elements,
the PCM can
further increase the thermal heat capacity of the floor or wall, thereby
allowing more heat from
the heating elements to be transferred to, and stored in, the floor or wall.
Further, this additional
heat is transferred and stored in the floor or wall at a lower heating element
temperature than
would be required without the use of a PCM. As a result, there is greater
overall efficiency in
the heating system. The reason for this phenomenon is that the transfer of
heat in the direction
opposite the tile surface (i.e., into the floor or wall) is considered lost
heat, and the amount of lost
heat generally increases as the heating element temperature increases. Thus,
if a lower heating
element temperature is used to achieve the same or better result (i.e., the
same amount of, or
more, heat transferred to the tile, and ultimately into the room in which the
tile system is
installed), then the overall efficiency of the system is increased.
The tile systems disclosed herein can be used in a variety of manners. For
example, the
tile systems can be used simply to transfer heat to and from the tile surface,
which will result in a
transfer of heat to and from the room or environment in which the tile system
is installed. In
addition, the tile systems can be used to decrease the consumption of energy,
for example in
heating, ventilation and air conditioning costs. This can be accomplished by
matching the heat
flow dynamics(e.g., including the actual storage and release of heat, the rate
of heat transfer, and
the like) of the PCM-containing tile system such that the release of heat can
be off-set to a
desired time of day. For example, the tile system can be configured, with the
appropriate choice
of PCM, tile material, and other optional components as described above, such
that heat is
collected by the PCM during the day, and released in the evenings when the sun
is down, the
load on the air conditioning system is lowered and its efficiency is
increased, and the electric
rates are lower. Similarly, the tile system can be configured such that heat
is transferred to the
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tile surface (and, ultimately, to the room or environment in which the tile
system is installed) by
the PCM during the day, and collected in the evenings, as may be desired for
the particular
application.
The various embodiments of the present invention are further illustrated by
the following
non-limiting example.
EXAMPLE 1: Calculated Benefits of PCM Incorporation
This example illustrates the effect that adding PCMs to ceramic tile products
can have.
In this analysis, the latent heat storage capability for a number of PCM
candidates, which
undergo their transition over the temperature range around room temperature
(i.e., about 20 C to
about 40 C), was compared with the sensible heat storage capacity of a typical
porcelain ceramic
tile, having a dimension of 12 inches by 12 inches and weighing about 1.5
kilograms, and a
composite tile comprising the same typical porcelain ceramic tile encapsulated
with about 350
grams of polyurethane over that same temperature range.
Assumptions made include volume available to accommodate PCMs in both tile
types
and the temperature range of interest. The volume of the back-pattern of the
back side of a
typical ceramic tile was set at 30 cubic centimeters. The heat storage
capacity of such a tile was
set at 24,060 Joules at the temperature range of interest. Similarly, the
volume of available space
in the groutless tile polymeric frame was set at 100 cubic centimeters; and
the heat storage
capacity of such a groutless tile was set at 33,657 Joules at the temperature
range of interest.
The known properties of the PCM candidates are provided in Table 31. These
properties
include transition temperature, heat of fusion, and density.
Based on the properties of the PCM candidates and the assumed volume and heat
storage
of the tile component, the data in Table 4 was calculated. As shown by the
data of Table 3, the
use of PCMs results in a latent heat storage capability that is a substantial
fraction of the original
i Douglas C. Hittle ["Phase Change Materials in Floor Tiles for Thermal Energy
Storage", October 2002; Award
No. DE-FC26-00NT40999]
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heat storage capacity for both tiles, particularly for the composite, or
groutless, tile, where one
could expect to incorporate more PCM into the structure. The data in Table 4
does not account
for the increase in sensible heat storage due to the capacity of the PCM, but
this storage
component would further increase the overall heat storage capacity and
effectiveness for tiles
containing the PCMs.
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TABLE 3
Material Transition Heat of Density (gram
Temperature Fusion per cubic
( C) (Joules centimeter)
per gram)
Solid state PCM
Pentaerythritol (PE) 188 269 1.390
Pentaglycerine (PG) 89 139 1.220
Neopentyl Glycol (NPG) 48 119 1.060
60% NPG + 40% PG 26 76 1.124
Normal Paraffin / Waxes
Tetradecane C14 5.5 228 0.825
Hexadecane C16 16.7 237 0.835
Octadecane C18 (Technical grade) 28 244 0.814
Eicosane C20 36.7 244 0.856
Commercially Available PCMs from Outlast Technologies
Kenwax 18 31.2 165 0.765
Kenwax 19 36.8 151 0.811
Technical Grade Octadecane 28 244 0.814
TABLE 4
Material Additional Heat Storage (Joules per square foot)
Ceramic Tile % Gain Groutless Tile % Gain
60% NPG + 40% PG 2563 11 % 8542 25%
Octadecane C18 (Technical grade) 5958 25% 19862 59%
Eicosane C20 6266 26% 20886 62%
Kenwax 18 3787 16% 12623 38%
Kenwax 19 3674 15% 12246 36%
Technical Grade Octadecane 5958 25% 19862 59%
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The embodiments of the present invention are not limited to the particular
components,
process steps, and materials disclosed herein as such components, process
steps, and materials
may vary somewhat. Moreover, the terminology employed herein is used for the
purpose of
describing exemplary embodiments only and the terminology is not intended to
be limiting since
the scope of the various embodiments of the present invention will be limited
only by the
appended claims and equivalents thereof.
Therefore, while embodiments of this disclosure have been described in detail
with
particular reference to exemplary embodiments, those skilled in the art will
understand that
variations and modifications can be effected within the scope of the
disclosure as defined in the
appended claims. Accordingly, the scope of the various embodiments of the
present invention
should not be limited to the above discussed embodiments, and should only be
defined by the
following claims and all equivalents.
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