Note: Descriptions are shown in the official language in which they were submitted.
CA 02684115 2009-10-28
HEATING UNIT FOR WARMING FLUID CONDUITS
BACKGROUND
Background and Relevant Art
[0001] The ability to distribute heat has provided a number of
opportunities for
increasing human comfort levels for certain activities and has made other
activities not
previously feasible able to be accomplished. One field where external heating
has
found particular use is in industries where individuals work with liquid or
gaseous
materials. For example, when transporting liquids or gases through a conduit,
such as a
hose or pipe, it can be desirable to maintain the liquid or gas at a desired
temperature or
within a desired temperature range. Maintaining the fluid conduit at a desired
temperature can provide numerous benefits, including preventing the liquid or
gas from
changing states during transportation, i.e., from a gas to a liquid, or from a
liquid to a
solid, freezing and/or breaking of the fluid conduit due to extreme
temperatures, as well
as delivering the liquid or gas at a particular temperature for an intended
use.
[0002] Heating units of various types have been previously implemented for
heating
pipes. Typically pipe warmers are relatively long, narrow straps that wrap
around a
pipe to provide heat to the pipe and its contents. However, typical pipe
warmers only
cover a portion of the pipe. Pipe warmers constructed in this fashion often
rely on the
conductive nature of a metallic pipe to distribute heat to the contents of the
pipe.
However, these types of pipe warmers typically result in uneven heating of the
pipe and
its contents. In particular, most pipe heaters turn on at an activation
temperature near
32 F and only remain on while the temperature is below the activation
temperature.
Thus, the portion of the pipe and its contents near the pipe warmer may be
maintained
at the activation temperature, while other portions of the pipe and its
contents may be
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CA 02684115 2009-10-28
,
insufficiently heated. If more even heat distribution is desired, multiple
pipe warmers
may be required. However, this requires the availability of multiple outlet
receptacles
and the use of additional power.
[0003] The subject matter claimed herein is not limited to
embodiments that solve
any disadvantages or that operate only in environments such as those described
above.
Rather, this background is only provided to illustrate one exemplary
technology area
where some embodiments described herein may be practiced.
BRIEF SUMMARY
[0004] One embodiment described herein is directed to a heating
unit for use in
providing evenly distributed heat to one or more fluid conduits. The heating
unit
includes a first pliable cover layer and a second pliable cover layer. A
pliable electrical
heating element is disposed between the first and the second cover layers. The
pliable
electrical heating element includes a heat generating element for converting
electrical
energy to heat energy and a heat spreading element that is attached to the
heat
generating element. The heat spreading element comprises carbon that is
thermally
coupled to the heat generating element for distributing the heat energy. A
thermal
insulation layer is attached to a first side of the pliable electrical heating
element and is
positioned adjacent the first cover layer. Additionally, a receiving power
connector is
electrically connected to the heat generating element and is configured to
couple to an
electrical power source. The heating unit further includes a sealing flap and
one or
more fasteners. The one or more fasteners are disposed in the first and second
pliable
cover layers in a fashion allowing the heating unit to be wrapped and secured
around
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CA 02684115 2009-10-28
one or more fluid conduits. The heating unit is sized to substantially cover
the entire
outer surface of the one or more fluid conduits.
[0005] This Summary is provided to introduce a selection of concepts in a
simplified form that are further described below in the Detailed Description.
This
Summary is not intended to identify key features or essential features of the
claimed
subject matter, nor is it intended to be used as an aid in determining the
scope of the
claimed subject matter.
100061 Additional features and advantages will be set forth in the
description which
follows, and in part will be obvious from the description, or may be learned
by the
practice of the teachings herein. Features and advantages of the invention may
be
realized and obtained by means of the instruments and combinations
particularly
pointed out in the appended claims. Features of the present invention will
become more
fully apparent from the following description and appended claims, or may be
learned
by the practice of the invention as set forth hereinafter.
BRIEF DESCRIPTION OF THE DRAWINGS
100071 In order to describe the manner in which the above-recited and other
advantages and features can be obtained, a more particular description of the
subject
matter briefly described above will be rendered by reference to specific
embodiments
which are illustrated in the appended drawings. Understanding that these
drawings
depict only typical embodiments and are not therefore to be considered to be
limiting in
scope, embodiments will be described and explained with additional specificity
and
detail through the use of the accompanying drawings in which:
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CA 02684115 2009-10-28
[0008] Figure 1 illustrates a exemplary embodiment of a heating unit
according to
the present invention;
[0009] Figure 2 illustrates a partially exploded view of the heating unit
of Figure 1;
[0010] Figure 3 illustrates an exploded view of some of the components of
the
heating unit of Figure 1 showing the construction of the heating unit with
adhesive
layers;
[0011] Figure 4 illustrates details of a heat spreading element of the
heating unit of
Figure 1;
[0012] Figures 5A and 5B illustrate comparative alternate temperature
arrangements
for the heating unit of Figure 1:
[0013] Figures 6A through 6C illustrate one method of applying the heating
unit of
Figure 1 to one or more fluid conduits.
DETAILED DESCRIPTION
[0014] Disclosed herein are embodiments of a heating unit for use in fluid
conduit
warming applications. In particular, embodiments may include a heating unit
configured to substantially cover the entire outer surface of one or more
fluid conduits,
including substantially the full circumference of the fluid conduit. As used
herein, fluid
conduit may include hoses, pipes, tubes, channels, and the like. Additionally,
while the
heating unit of the present invention is described as being used to heat fluid
conduits, it
will be appreciated that the heating unit may also be used to provide heat to
other
objects. For example, wires, poles, and the like can also be heated using the
heating
unit disclosed herein.
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=
[0015] The heating unit includes a heating element which
provides heat and spreads
the heat over the surface of the heating unit. The heating unit may also
include an
insulation layer to prevent heat from being lost to an environment external to
the fluid
conduit. For example, Figure 1 illustrates one embodiment of a heating unit
configured
as a fluid conduit warmer 100 covering multiple fluid conduits 10. While
Figure 1
illustrates the heating unit as a fluid conduit warmer, it will be appreciated
that the
heating unit can be sized, shaped, or otherwise configured to provide heat to
other types
of conduits and similar objects.
[0016] An example of components implemented in one embodiment
is illustrated in
Figures 2 and 3. These Figures illustrate the construction of the heating
unit, including
materials used to assemble the heating unit. Figure 2 illustrates a partially
exploded
view illustrating the flexible nature of a heating unit 100 that includes a
first cover layer
102, an insulation layer 104, a heating element 106, and a second cover layer
108. In
some embodiments, the heating element 106 includes a heat generating strip 114
and a
heat spreading element 122, each of which will be described in greater detail
below.
The heating unit 100 further includes an incoming electrical connector 110.
The
heating unit can also include an outgoing electrical connector 112. While the
example
illustrated in Figure 2 is illustrated as partially exploded, some finished
embodiments
may be manufactured such that the insulation layer 104 and the heating element
106
may be sealed between the first cover layer 102 and the second cover layer
108.
Sealing processes and details will be discussed in more detail below.
[0017] Figure 3 illustrates a fully exploded view of the
heating unit 100 so as to
more clearly illustrate the individual components of the heating unit 100. As
illustrated
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CA 02684115 2009-10-28
in Figure 3, first and second cover layers 102 and 108 are generally planar
sheets of
material that are disposed on opposing sides of the internal components of
heating unit
100. During construction of heating unit 100, first cover layer 102 is
positioned as
illustrated in Figure 3. Next, insulation layer 104 is positioned on top of
first cover
layer 102 and heating element 106 is then positioned on top of insulation
layer 104.
Finally, second cover layer 108 is positioned on top of heating element 106.
With the
various components of heating unit 100 so positioned, the peripheral edges of
first and
second layers 102 and 108 can be joined, sealed, or otherwise closed.
[0018] Heating unit 100, constructed as described herein, can be used in
numerous
applications that require heat to be transferred to an object or surface. As
described
herein, the various components of heating unit 100 are flexible such that
heating unit
100 can be wrapped around objects, laid on top, beneath, or hung adjacent
objects or
surfaces, and rolled or folded up when not in use. In order to ensure that
heating unit
100 and its various components retain their shape and their positions relative
to one
another, the various components of heating unit 100 can be attached to one
another. For
example, the various components of heating unit 100 can be glued, bonded, or
otherwise held together. Attaching the components of heating unit 100 together
helps to
prevent the components from moving relative to one another within heating unit
100.
[0019] For example, attaching heating element 106 to insulation layer 104
ensures
that heating element 106 will stay positioned next to insulation layer 104 and
will not
sag, bunch, or otherwise move within heating unit 100. In particular, because
insulation
layer 104 is formed of a stiffer material than heating element 106, attaching
heating
element 106 to insulation layer 104 provides stiffness to heating element 106.
While
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CA 02684115 2009-10-28
insulation layer 104 is referred to as being formed of a "stiffer" material,
it will be
appreciated that in some embodiments insulation layer 104 may still be
flexible such
that it can be wrapped around a barrel or folded around a box, for example.
Similarly,
heat generating strip 114 and heat spreading element 122 can be attached to
one another
to ensure that heat generating strip 114 is properly positioned on heat
spreading element
122, even after heating unit 100 is rolled, folded, and used several times.
Likewise,
heating element 106 and/or insulation layer 104 can be attached to first
and/or second
cover layers 102 and 108 to prevent the internal components of heating unit
100 from
moving within first and second cover layers 102 and 108.
[00201 Figure 3
illustrates one exemplary embodiment in which various
components of heating unit 100 are attached together. For convenience of
illustration,
incoming electrical connector 110 and outgoing electrical connector 112 are
omitted
from Figure 3. In the embodiment illustrated in Figure 3, there are two
interfaces
between the heating unit components for attachment between the components. As
used
herein, an attachment interface is a surface where two or more components of
heating
unit 100 are attached together. The first attachment interface 136 is between
the top
surface of insulation layer 104 and the bottom surface of heating element 106.
As noted
herein, heating element 106 includes a heat generating strip 114 mounted on a
heat
spreading element 122. In the illustrated embodiment, the heat generating
strip 114 is
mounted on the bottom surface of heat spreading element 122 such that heat
generating
strip 114 is positioned between heating spreading element 122 and insulation
layer 104.
Attachment interface 136 is therefore between the top surface of insulation
layer 104
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and the bottom surface of heat spreading element 122, with heat generating
element 114
mount on heat spreading element 122 therebetween.
[0021] The
second attachment interface 140 is between the top surface of heat
spreading element 122 and the bottom surface of second cover layer 108. In
other
embodiments, there is only the first attachment interface 136. Still in
other
embodiments, there are additional attachment interfaces, such as between the
bottom
surface of insulation layer 104 and the top surface of first cover layer 102.
[0022]
Attachment interfaces 136 and 140 can be created by attaching the above
identified components of heating unit 100 in any suitable manner so that the
components maintain their relative positions one to another. In one exemplary
embodiment, attachment interfaces 136 and 140 are created using an adhesive
between
the components of heating unit 100. One such adhesive suitable for attaching
together
the components of heating unit 100 is 30-NF FASTBONDTm available from 3M
located
in St. Paul, Minnesota.
FASTBONDTm is a non-flammable, heat resistant,
polychloroprene base adhesive.
[0023] In order
to properly adhere the components of heating unit 100 together with
FASTBONDTm, the interfacing surfaces should be clean and dry. With the
surfaces
prepared, a uniform coat of FASTBONDTm is applied to both interfacing
surfaces.
After applying, the FASTBONDTm is allowed to dry completely, which typically
takes
about 30 minutes. Once the FASTBONDTm on both surfaces is dry, the two
FASTBONDTm coated surfaces are joined together.
[0024] For
example, when attaching insulation layer 104 to heat spreading element
122, a coat of FASTBONDTm is applied to the top surface of insulation layer
104 and
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,
the bottom surface of heat spreading element 122 over the top of heat
generating strip
114. Once the FASTBONDTm on each surface is dry, heat spreading element 122 is
positioned on top of insulation layer 104 and the two layers of FASTBONDTm
adhere to
one another. The same process can be followed to attach second cover layer 108
to the
top surface of heat spreading element 122 or to attach the first cover layer
102 to the
bottom surface of insulation layer 104.
[0025]
In the illustrated embodiment, second cover layer 108 is attached to
heating
element 106 and heating element 106 is attached to insulation layer 104.
Notably,
however, insulation layer 104 and heating element 106 can be left unattached
from first
and/or second cover layers 102 and 108. Not attaching insulation layer 104 and
heating
element 106 to first and/or second cover layers 102 and 108 provides for
flexibility and
give in heating unit 100 when heating unit 100 is folded, rolled, or wrapped
around an
object. Specifically, heating unit 100 is configured to be wrapped around an
object such
that second cover layer 108 is adjacent the object and first cover layer 102
is positioned
away from the object (see Figure 1 in which first cover layer 102 is showing).
When
first and/or second cover layers 102 and 108 are not attached to insulation
layer 104
and/or heating element 106, first and/or second cover layers 102 and 108 are
able to
move relative to insulation layer 104 and heating element 106 and stretch as
heating
unit 100 is wrapped around an object. In other embodiments, however,
insulation layer
104 and first cover layer 102 are attached to one another while heating
element 106 and
second cover layer 108 are attached to one another. For example, when heating
unit
100 is used on flat surfaces, such as the ground or a roof, the need for first
and second
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CA 02684115 2009-10-28
cover layers 102 and 108 to be able to move relative to insulation layer 104
and heating
element 106 is not as great.
[0026] The following discussion will now treat additional details and
embodiments
of the various components of the heating unit 100. Referring now to Figure 4
and as
noted above, in some embodiments the heating element 106 includes a heat
generating
strip 114. The heat generating strip 114 may be, for example, an electro-
thermal
coupling material or resistive element. In some embodiments, the heat
generating strip
may be a copper, copper alloy or other conductor. In one embodiment, the
conductor is
a network of copper alloy elements configured to generate about 9W of power
per linear
foot of the heat generating strip. This may be achieved by selection of
appropriate
alloys for the heat generating element 114 in combination with selection of
appropriate
heat generating element wire sizes and circuit configurations. The conductor
may
convert electrical energy to heat energy, and transfer the heat energy to the
surrounding
environment. Alternatively, the heat generating element 114 may comprise
another
conductor, such as semiconductors, ceramic conductors, other composite
conductors,
etc., capable of converting electrical energy to heat energy. The heat
generating strip
114 may include one or more layers for electrical insulation, temperature
regulation,
and ruggedization.
[0027] Notably, other heat sources may be used in addition to or as
alternatives to
the heat generating strip. For example, some embodiments may include the use
of
exothermic chemical reactions to generate heat or heating tubes which a heated
liquid
runs through.
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[0028] With continuing reference to Figure 4, the heat generating strip 114
is
illustrated with two heat generating conductors 116 and 118. One of the two
conductors
is connected to a first terminal of the incoming electrical connector 110
while the other
conductor is connected to a second terminal of the electrical connector 110.
The first
and second terminals may be connected to electrical sources as appropriate,
such as
generator supplied AC or DC sources, batteries, power inverters, etc. The two
conductors 116 and 118 may be connected at one end to create a closed circuit
allowing
current to flow through the two conductors to generate heat.
[0029] In the example illustrated in Figure 4, the two conductors are
connected
through a thermostat 120. In this example, the thermostat 120 includes a hi-
metal strip
based temperature control that disconnects the two conductors 116 and 120 at a
pre-
determined temperature. Examples of predetermined temperatures may be 33 F, 50
F,
75 F, 90 F, 110 F, and 130 F. Notably, these are only examples, and other
temperatures may be alternatively used. This can be used to regulate the
temperature of
the heating unit 100 to prevent overheating, or to maintain the temperature at
a
temperature of about the pre-determined temperature.
[0030] Embodiments may be implemented where the temperature is determined
by
selecting a thermostat 120 with a fixed temperature rating. Other embodiment
may be
implemented where the temperature setting of the thermostat can be adjusted to
a
predetermined temperature at manufacturing time. In some embodiments, the
thermostat may be user accessible to allow a user to adjust the thermostat
settings.
While in the example illustrated the thermostat is located at the ends of the
conductors
116 and 118, it should be appreciated that in other embodiments the thermostat
may be
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placed inline with one of the conductors 116 and 118. Additionally, some
embodiments
may include low voltage control circuitry including temperature control
functionality,
which controls application of power to the conductors 116 and 118 to regulate
temperature.
[0031] It
should further be appreciated that embodiments may be implemented
where other temperature or current protections are included. For
example,
embodiments may include magnetic and/or thermal circuit breakers, fuses,
semiconductor based over-current protection, ground fault protection, arc
fault
protection, etc. In some embodiments, these may be located at the ends of the
conductors 116 and 118 or inline with one or more of the conductors 116 and
118 as
appropriate.
[0032]
Additionally, controlling temperature may be accomplished by controlling
the density of the heat generating element 114. This may be accomplished by
controlling spacing between different portions of the heat generating element
allowing
for more or less material used for the heat generating element 114 to be
included in the
heating unit 100. This method may be especially useful when heat generating
elements
have a constant Wattage output per length of heat generating element. Thus a
longer
heat generating element 114 provides more heat than a shorter heat generating
element
114. Figures 5A and 5B illustrate a comparative example where two alternative
embodiments are illustrates. Each of the embodiments illustrates a heating
unit 100 of
the same size, but with different heat generating elements densities. The
first
embodiment illustrates a heating element 106A with a less dense heat
generating
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=
element 114A, while the second embodiment illustrates a heating element 106B
with a
more dense heat generating element 114B.
[0033]
By way of the method described herein, the temperature of fluid conduits
10
can be regulated. In particular, by way of a thermostat or the selection and
configuration of the heating unit components, the temperature of the fluid
conduits can
be maintained at a desired temperature or within a desired temperature range.
For
example, when a fuel supply, such as propane gas, is flowing through fluid
conduit 10,
it is important to maintain the propane in its gaseous form to prevent
interruptions to the
flow of the propane. Thus, to prevent the propane from changing into its
liquid form,
the propane must be maintained above its boiling point temperature, which is
approximately -43 F. Similarly, if water is flowing through fluid conduit 10,
it may be
important to maintain the water at a desired temperature. For example,
maintaining the
water above 32 F will prevent the water from freezing. Additionally, the fluid
or gas
flowing through fluid conduit 10 may need to be maintained at a desired
temperature for
an intended use at a destination location. For example, if water is flowing
through fluid
conduit 10 to a shower facility, it may be desirable to maintain the water at
a higher
temperature, such as 80 F. Thus, the thermostats, configuration of the heating
unit
components, and the temperature protection mechanisms described herein enable
a fluid
conduit 10 to be maintained at a desired temperature or within a desired
temperature
range. By way of example, some desired temperatures may be -43 F to 0 F, 33 F
to
50 F , 75 to 100 F, and 90 F to 130 F. Notably, these are only examples, and
other
temperatures may be alternatively used.
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[0034] Returning attention to Figure 4, as noted above, the electrical
heating
element 106 may further include a heat spreading element. In general terms,
the heat
spreading element 122 is a layer of material capable of drawing heat from the
heat
generating element 114 and distributing the heat energy away from the heat
generating
element 114. Specifically, the heat spreading element 122 may comprise a
metallic foil,
wire mesh, carbon mesh, graphite, a composite material, or other material.
[0035] The heat-spreading element 122 in one embodiment is an electrically-
conductive material comprising carbon. Graphite is one example of an
electrically-
conductive material comprising carbon. However, other suitable materials may
include
carbon-based powders, carbon fiber structures, or carbon composites. Those of
skill in
the art will recognize that material comprising carbon may further comprise
other
elements, whether they represent impurities or additives to provide the
material with
particular additional features. Materials comprising carbon may be suitable so
long as
they have sufficient thermal conductivity to act as a heat-spreading element.
In one
embodiment, the material comprising carbon comprises sufficient electrical
conductivity to act as a ground connection, as will be discussed in more
detail below.
The heat-spreading element 122 may further comprise a carbon derivative, or a
carbon
allotrope.
[0036] One example of a material suitable for a heat spreading element 122
is a
graphite-epoxy composite. The in-plane thermal conductivity of a graphite-
epoxy
composite material is approximately 370 watts per meter per Kelvin, while the
out of
plane thermal conductivity of the same material is 6.5 watts per meter per
Kelvin. The
thermal anisotropy of the graphite/epoxy composite material is then 57,
meaning that
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heat is conducted 57 times more readily in the plane of the material than
through the
thickness of the material. This thermal anisotropy allows the heat to be
readily spread
out from the surface which in turn allows for more heat to be drawn out of the
heating
element 114.
[0037] The heat spreading element 122 may comprise a material that is
thermally
isotropic in one plane. The thermally isotropic material may distribute the
heat energy
more evenly and more efficiently. One such material suitable for forming the
heat
spreading element 122 is GRAFOIL available from Graftech Inc. located in
Lakewood, Ohio. In particular, GRAFOIL is a flexible graphite sheet material
made
by taking particulate graphite flake and processing it through an
intercalculation process
using mineral acids. The flake is heated to volatilize the acids and expand
the flake to
many times its original size. The result is a sheet material that typically
exceeds 98%
carbon by weight. The sheets are flexible, lightweight, compressibly
resilient,
chemically inert, fire safe, and stable under load and temperature. The sheet
material
typically includes one or more laminate sheets that provide structural
integrity for the
graphite sheet.
[00381 Due to its crystalline structure, GRAFOIL is significantly more
thermally
conductive in the plane of the sheet than through the plane of the sheet. This
superior
thermal conductivity in the plane of the sheet allows temperatures to quickly
reach
equilibrium across the breadth of the sheet.
[0039] Typically, the GRAFOIL will have no binder, resulting in a very low
density, making the heated cover relatively light while maintaining the
desired thermal
conductivity properties. For example, the standard density of GRAFOIL is
about 1.12
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g/ml. It has been shown that three stacked sheets of 0.030" thick GRAFOIL C
have
similar thermal coupling performance to a 0.035" sheet of cold rolled steel,
while
weighing about 60% less than the cold rolled steel sheet.
100401 Another product produced by GrafTech Inc. that is suitable for use
as a heat
spreading element 122 is EGRAF SPREADERSHIELDTM. The thermal conductivity
of the SPREADERSHIELDTM products ranges from 260 to 500 watts per meter per
Kelvin within the plane of the material, and that the out of plane (through
thickness)
thermal conductivity ranges from 6.2 down to 2.7 watts per meter per Kelvin.
The
thermal anisotropy of the material ranges from 42 to 163. Consequently, a
thermally
anisotropic planar heat spreading element 122 serves as a conduit for the heat
within the
plane of the heat spreading element 122, and quickly distributes the heat more
evenly
over a greater surface area than a foil. The efficient planar heat spreading
ability of the
planar heat spreading element 122 also provides for a higher electrical
efficiency, which
facilitates the use of conventional power supply voltages such as 120 volts on
circuits
protected by 20 Amp breakers, instead of less accessible higher voltage power
supplies.
In some embodiments, the heat spreading element 122 is a planar thermal
conductor. In
certain embodiments, the graphite may be between 1 thousandth of an inch thick
and 40
thousandths of an inch thick. This range may be used because within this
thickness
range the graphite remains pliable and durable enough to withstand repeated
rolling and
unrolling as the heating unit 100 is unrolled for use and rolled up for
storage.
100411 The heat spreading element 122 may comprise a flexible thermal
conductor.
In certain embodiments, the heat spreading element 122 is formed in strips
along the
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length of the heat generating element 114. In alternative embodiments, the
heat
spreading element 122 may comprise a contiguous layer.
[0042] In some embodiments, the heat spreading element 122 may also include
functionality for conducting electrical energy and converting electric energy
to thermal
energy in a substantially consistent manner throughout the heat spreading
element.
Graphite heat spreading elements may be particularly well suited for these
embodiments. In such an embodiment, a heat generating element 114 may be
omitted
from the heating unit 100 as the heat spreading element 122 serves the
purposes of
conveying current, producing heat due to resistance, and evenly distributing
the heat.
[0043] The small size and thickness of the graphite minimizes the weight of
the heat
spreading element 122. The graphite containing heat spreading element may be
pliable
such that the graphite can be rolled lengthwise without breaking the
electrical path
through the graphite.
[0044] In some embodiments, the heat spreading element 122 may include an
insulating element formed of a thin plastic layer on both sides of the heat-
spreading
element 122. The insulating element may additionally provide structure to the
heat-
spreading material used in the heat spreading element 122. For example, the
insulating
element may be polyethylene terephthalate (PET) in the form of a thin plastic
layer
applied to both sides of heat-spreading element 122 comprising graphite. Those
of skill
in the art will appreciate that such a configuration may result in the
insulating element
lending additional durability to the heat-spreading element 122 in addition to
providing
electrical insulation, such as electrical insulation from the electrical
current in the heat
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generating element 114. It should be noted that the heating generating element
114 may
include its own electrical insulation as well as described above.
[0045] In some embodiments, the heat spreading element 122 may include a
heat
conducting liquid such as water, oil, grease, etc.
[0046] In certain embodiments, the heat generating element 114 is in direct
contact
with the heat spreading element 122 to ensure efficient thermo-coupling.
Alternatively,
the heat spreading element 122 and the heat generating element 114 are
integrally
formed. For example, the heat spreading element 122 may be formed or molded
around
the heat generating element 114. Alternatively, heat generating strip 114 and
the heat
spreading element 122 may be adhesively coupled as described herein.
[0047] Notably, while temperature may be controlled with the use of
thermostats as
described above, other embodiments may implement other design criteria to
control
temperature. For example, some embodiments may use appropriate selection of
the
heat spreading element 122 and/or the arrangement of the heat generating
element 114.
Illustratively, the heat retention properties of the heat spreading element
122 may be a
factor in regulating temperatures at which a heating unit 100 will operate.
Further, the
density of the heat generating element 114 with respect to the size of the
heating unit
100 or the heat spreading element 122 can be used set the operating
temperatures or to
regulate temperatures.
[0048] In some embodiments, the heating unit can be sized to substantially
enclose
fluid conduits of various lengths and diameters. Additionally, as described
elsewhere
herein, multiple heating units can be coupled together to provide heat to
fluid conduits
of nearly any size. In one exemplary embodiment, the heating unit is
approximately
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twelve and one half (121/2) feet long and one (1) foot wide. In another
exemplary
embodiment, the heating unit is approximately six (6) feet long and eight (8)
inches
wide. In still another embodiment, the heating unit is approximately twenty-
five (25)
feet long and two and one half (21/2) feet wide. It will be appreciated,
however, that the
heating unit can be sized and configured to substantially enclose fluid
conduits of any
size or shape.
[0049] Returning once again to Figures 2 and 3, Figures 2 and 3 illustrate
an
insulating layer 104. The insulating layer 104 may be used to reflect or
direct heat or to
prevent heat from exiting in an undesired direction. For example, it may be
desirable to
have all or most of the generated heat be directed towards a particular
surface of the
heating unit 100. In the embodiment illustrated in Figures 1 and 6A-6C, for
example, it
may be desirable to direct heat towards the walls of the fluid conduits 10
while directing
heat away from an exterior environment in which the fluid conduits 10 are
located. In
the example illustrated, it may be desirable to have heat directed towards the
side of the
heating unit 100 which includes the second cover layer, while directing heat
away from
the side that includes the first cover layer. The insulating layer 104 may be
used to
accomplish this task. Some exemplary embodiments of the heating unit have been
implemented where about 95% of heat generated is directed towards a desired
surface
of the heating unit.
[0050] The insulating layer 104 may include a sheet of polystyrene, cotton
batting,
GORE-TEX , fiberglass, foam rubber, etc. In certain embodiments, the
insulating
layer 104 may allow a portion of the heat generated by the heat generating
element 114
to escape the top of the second cover layer 108 if desired. For example, the
insulating
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CA 02684115 2009-10-28
layer 104 may include a plurality of vents to transfer heat to the second
cover layer 108.
In certain embodiments, the insulating layer 104 may be integrated with either
the first
cover layer 102 or the second cover layer 108. For example, the first cover
layer 102
may include an insulation fill or batting positioned between two films of
nylon.
[0051] In some embodiments, first and second cover layers 102 to 108 may
comprise a textile fabric. The textile fabric may include natural or synthetic
products.
For example, the first and second cover layers 102 to 108 may comprise burlap,
canvas,
cotton or other materials. In another example, first and second cover layers
102 to 108
may comprise nylon, vinyl, or other synthetic textile material. The first and
second
cover layers 102 to 108 may comprise a thin sheet of plastic, metal foil,
polystyrene, or
other materials.
[0052] In manufacturing the heating unit 100, the heating element 106 and
insulation layer 104 may be sealed between the first and second cover layers
102 and
108. As illustrated in Figures 2 and 3, the first and second cover layers 102
and 108
extend slightly beyond the heating element 106 and insulation layer 104. This
allows
the first and second cover layers 102 and 108 to be sealed, such as by using
an adhesive,
heat welding, or another other appropriate method or combination of methods.
[0053] Additionally, the heating unit 100 may be constructed such that the
first and
second cover layers 102 and 108 may include one or more fasteners 124 for
securing or
connecting the heating unit 100. In some embodiments, the fasteners 124 may be
attached or formed into the corners of the heating unit 100. Additionally,
fasteners 124
may be distributed about the perimeter of the heating unit 100. In some
embodiments,
the fastener 124 is a hook and loop fastener such as Velcro . For example, the
heating
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CA 02684115 2009-10-28
unit 100 may include a hook fabric on one side and a loop fabric on an
opposite side. In
other alternative embodiments, the fastener 124 may include grommets, snaps,
zippers,
adhesives, or other fasteners. Further, additional objects may be used with
the fasteners
to accomplish fastening. For example, when grommets are used, elastic cord,
such as
fixed or adjustable bungee cord may be used to connect to grommets on opposite
sides
of the heating unit 100. This may be used, for example, to securely wrap the
heating
unit around an object, such as a fluid conduit.
[0054] A number of fastener arrangements may be implemented for securing
the
opposing sides of the heating unit together. For example, Figure 1 illustrates
a first
portion of the heating unit 100 having a plurality of grommets therein.
Associated with
each of the grommets is an elastic chord that can be wrapped around the
heating unit
with both ends of the chord being attached to its associated grommet. Other
fasteners
that can be employed to secure the heating unit around fluid conduits include
snap
fasteners, zippers, hook and loop type fasteners such as VELCRO , and the
like.
Fasteners 124 can be adapted to enable selective coupled and decoupling to
allow
heating unit 100 to be selectively opened and closed. Alternatively, fasteners
124 can
be adapted to permanently close heating unit 100. For example, grommet
fasteners 124
can be secured to opposing portions of heating unit 100, where a single
grommet may
be secured to both opposing portions such that the heating unit permanently
maintains a
substantially wrapped shape.
[0055] In some embodiments, the first cover layer 102 may be positioned at
the top
of the heating unit 100 and the second cover layer 108 may be positioned on
the bottom
of the heating unit 100. In certain embodiments, the first cover layer 102 and
the
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CA 02684115 2009-10-28
second cover layer 108 may comprise the same or similar material.
Alternatively, the
first cover layer 102 and the second cover layer 108 may comprise different
materials,
each material possessing properties beneficial to the specified surface
environment.
[0056] For example, the first cover layer 102 may comprise a material that
is
resistant to sun rot such as such as polyester, plastic, and the like. The
second cover
layer 108 may comprise material that is resistant to mildew, mold, and water
rot such as
nylon. The cover layers 102 and 108 may comprise a highly durable material.
The
material may be textile or sheet, and natural or synthetic. For example, the
cover layers
102, 108 may comprise a nylon textile. Additionally, the cover layers 102, 108
may be
coated with a water resistant or waterproofing coating. For example, a
polyurethane
coating may be applied to the outer surfaces of the cover layers 102, 108.
Additionally,
the top and bottom cover layers 102, 108 may be colored, or coated with a
colored
coating such as paint. In some embodiments, the color may be selected based on
heat
reflective or heat absorptive properties. For example, the top layer 102 may
be colored
black for maximum solar heat absorption. The bottom layer 102 may be colored
grey
for a high heat transfer rate or to maximize heat retention beneath the cover.
[0057] As illustrated in Figures 1, 2, and 6A-6C, the heating unit can also
include a
sealing flap 142 that extends along the length of the heating unit 100 that is
adapted to
reduce the amount of heat lost when the heating unit 100 is wrapped around a
fluid
conduit. Along one edge of the heating unit 100 illustrated in Figure 2, the
top and
bottom cover layers 102, 108 extend beyond the heating element 106 and the
insulating
layer 104 to form sealing flap 142. While the illustrated embodiment does not
include
heating element 106 or insulating layer 104 in the sealing flap 142 of heating
unit 100,
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CA 02684115 2009-10-28
it will be appreciated that heating element 106 and insulating layer 104 can
also extend
into the sealing flap 142 of heating unit 100. It will be appreciated that
sealing flap 142
can be formed independently of top and bottom cover layers 102, 108. For
example,
sealing flap 142 can be formed separately from top and bottom cover layers
102, 108
and attached to top and/or bottom cover layers 102, 108/
[0058] Heating unit 100 can be wrapped and secured around the outer wall(s)
of one
or more fluid conduits as illustrated in Figures 6A-6C. Specifically, as
illustrated in
Figure 6A, with heating unit 100 laid open, the fluid conduits can be
positioned
generally in the middle thereof such that the lengths of the heating unit and
the fluid
conduits are parallel. So positioned, the heating unit 100 can be folded over
the fluid
conduits as shown in Figure 6B. As noted herein, each of the components of
heating
unit 100 is pliable, thus enabling heating unit 100 to be folded over or
wrapped around
fluid conduit 10. To facilitate the folded of heating unit 100 over fluid
conduit 10,
insulating layer 104 can include a score therein.
[00591 With the heating unit 100 folded over the fluid conduit 10, the
sealing flap
142 can then be folded over to cover any openings between the opposing sides
of the
heating unit 100. Fasteners 124 can then be used to secure the heating unit
100. For
example, in Figure 6C, fasteners 124 comprise grommets and elastic chords. The
grommets and elastic chords are spaced along at least one of the long edges of
heating
unit 100. The elastic chords can be wrapped around the heating unit 100 to
maintain
heating unit 100 on the fluid conduits.
[0060] The embodiment shown in Figures 1-3 includes a six (6) foot power
cord
132 connected to the heat generating element 114. Other cord lengths may also
be
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CA 02684115 2009-10-28
implemented within the scope of embodiments of the invention. The power cord
may
additionally be connected to an incoming electrical connector 110 such as an
AC power
plug, bare wire connector, alligator clip connectors, a cigarette lighter plug
connector or
other appropriate connector for connecting the power cord to a source of
power.
[0061] Notably, some embodiments may be implemented with interchangeable
incoming electrical connectors. For example, embodiments may include a kit
which
includes a heating unit 100 with a two pin auto connector. The kit may further
include a
wire without an additional connector connected to a mating two pin auto
connector, a
set of alligator clips connected to a mating two pin auto connector, and a
cigarette
lighter plug connected to a mating two pin auto connector. A user can then
select an
appropriate incoming electrical connector 110. For example, a user may select
the wire
without an additional connector if the heating unit is to be hard wired to an
electrical
system, such as an automobile, boat, or other electrical system. Cigarette
lighter plugs
or alligator clip connectors could be selected for more temporary connectors.
[0062] Some embodiments may also include various fault protections. For
example, embodiments may include an incoming electrical connector 110 which
includes ground fault circuit interruption capabilities so as to make the
heating unit 100
suitable for use in wet or outdoor environment. Embodiments may include over
current
protection such as breakers or fuses. Embodiments may include arc fault
circuit
interruption capabilities to address problems related to fatigue of wires or
crushing of
wires.
[0063] Embodiments may further include provisions for grounding the heating
unit
100. For example, the heating unit is illustrated in Figures 1-3 includes an
incoming
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CA 02684115 2009-10-28
electrical connector in the form an AC plug, which includes two power
terminals 128
and a grounding terminal 130. The power cord 132 may include three conductors,
one
connected to each power terminal 128, and the third connected the grounding
terminal
130. The two conductors connected each to a respective power terminal 128
connect as
described above to the heat generating element 114. The third conductor may be
connected so as to ground the heating unit 100. This may be done, for example
by
including an electrically conductive layer (not shown) in the heating unit 100
which is
electrically connected to the grounding terminal 130.
[0064] In an
alternative embodiment, due to the electrically conductive nature of the
heat spreading element 122 when a graphite based material is used for the heat
spreading element 122, the grounding terminal 130 may be electrically coupled
to the
heat spreading element 122. This may be accomplished in one example, by using
a
ground coupling in the form of a spade connector or other connector which
passes
through a protective layer of the heat spreading element so as to be in
electrical contact
with the conductive portions of the heat spreading element 122. In one
embodiment,
the ground couplings comprise planar rectangular metal connection blades that
would
normally be used as the hot and/or neutral connection blades of a power
coupling such
as a power coupling which connects to a power source. In one embodiment,
ground
coupling spade connector further comprises barbs configured to cut into the
heat-
spreading element 122 and engage the heat-spreading element 122 such that the
blade
does not come loose. In alternative embodiments, the blade may be connected to
the
heat-spreading element 122 with an adhesive that does not electrically
insulate the heat-
spreading element 122 from the blade. In addition, the plane of the blade may
be placed
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CA 02684115 2013-07-25
parallel to the plane of the heat-spreading element 122 such that a maximum
amount of
the surface area of the blade is in direct contact with the heat-spreading
element 122.
Such a configuration may increase the contact area between the two surfaces
and results
in a better electrical and physical connection. Furthermore, such a
configuration can
leverage the lower in-plane resistivity of the heat-spreading element 122.
[0065] Additionally, some embodiments may include an outgoing electrical
connector 112. This may be used, for example to allow chaining of heating
units
together. In the example illustrated, the outgoing electrical connector 112 is
connected
electrically to the incoming electrical connector 110 through conductors 126
passing
through the heating unit 100. Other embodiments may allow the incoming
electrical
connector 110 and outgoing electrical connector 112 to be more or less
proximate to
each other as appropriate.
[0066] A grounding terminal 132 of the outgoing electrical connector 112
may be
electrically connected to the grounding terminal 130 of the incoming
electrical
connector 110. This may be accomplished by wiring the two terminals together
or
connecting both grounding connectors to the same grounding surface, such as a
grounding layer, or to the heat spreading element 122 as described above.
[0067] Some embodiments may further include timing circuitry such that a
user can
select when heating should occur. The timer may be an electronic controlled
device
supplied by the electrical connector 112 and may include internal switching
such as
relays or solid state switches for supplying power to the heat generating
strip 114.
[0068] The present invention may be embodied in other specific forms. The
described embodiments are to be considered in all respects only as
illustrative and not
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CA 02684115 2013-07-25
restrictive. The scope of the claims should not be limited by the preferred
embodiments
set forth in the examples, but should be given the broadest interpretation
consistent with
the description as a whole.
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