Note: Descriptions are shown in the official language in which they were submitted.
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ENERGY EXCHANGE ASSEMBLY WITH
MICROPOROUS MEMBRANE
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application relates to and claims priority benefit
from United
States Patent Application No. 14/192,019, entitled "Energy Exchange Assembly
With
Microporous Membrane," filed February 27, 2014, which, in turn, relates to and
claim
priority benefits from United States Provisional Patent Application No.
61/784,638, entitled
"Air-To-Air Energy Recovery Core With Microporous Membrane," filed March 14,
2013,
which is hereby expressly incorporated by reference in its entirety.
BACKGROUND OF THE DISCLOSURE
[0002] Embodiments of the present disclosure generally relate to an
energy
exchange assembly, such as an energy recovery core, that incorporates a
microporous
membrane.
[0003] Energy exchange assemblies are used to transfer energy, such as
sensible
and/or latent energy, between fluid streams. For example, air-to-air energy
recovery cores
are used in heating, ventilation, and air conditioning (HVAC) applications to
transfer heat
(sensible energy) and moisture (latent energy) between two airstreams. A
typical energy
recovery core is configured to precondition outdoor air to a desired condition
through the
use of air that is exhausted out of the building. For example, outside or
supply air is
channeled through the energy recovery core in proximity to exhaust air. Energy
between the
supply and exhaust air streams is transferred therebetween. In the winter, for
example, cool
and dry outside air is warmed and humidified through energy transfer with the
warm and
moist exhaust air. As such, the sensible and latent energy of the outside air
is increased,
while the sensible and latent energy of the exhaust air is decreased. The
energy recovery
core typically reduces post-conditioning of the supply air before it enters
the building,
thereby reducing overall energy use of the system.
[0004] Air-to-air recovery cores may include a membrane through which
heat
and moisture are transferred between air streams. The membrane may be
separated from
adjacent membranes using a spacer. In an energy recovery core, the amount of
heat
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transferred is generally determined by a temperature difference and convective
heat transfer
coefficient of the two air streams, as well as the material properties of the
membrane. The
amount of moisture transferred in the core is generally governed by a humidity
difference
and convective mass transfer coefficients of the two air streams, but also
depends on the
material properties of the membrane.
[0005] One known type of membrane used in an energy recovery core is a
non-
porous hygroscopic membrane. This membrane has a hygroscopic coating which is
bonded
to a resin or paper-like substrate material. The hygroscopic coating is used
to drive moisture
transfer through the membrane, while the substrate is used for an added layer
of support.
The hygroscopic coating may be configured to allow very little air transfer
through the
membrane at standard operating differential pressures. However, the ability
for the
membrane to transfer moisture typically depends on the relative humidity of
the air. In a
very humid environment, hygroscopic membranes have a low vapor diffusion
resistance. In
low humidity environments, however, hygroscopic membranes have a high vapor
diffusion
resistance. As such, an energy recovery core including such membranes
generally exhibits a
large change in latent effectiveness between heating and cooling conditions.
[0006] Another known type of membrane used in an energy recovery core
is a
composite polymer membrane. The composite polymer membrane has a thin vapor-
promoting polymer film coated on a porous polymer substrate. The polymer film
is used to
drive moisture transfer through the membrane and prohibit airflow through the
membrane at
standard operating differential pressures. The porous polymer substrate may be
used to
reinforce the membrane while allowing the transfer of vapor therethrough. In
adding and
bonding multiple polymer layers together, however, the resistance to moisture
transfer (i.e.,
the vapor diffusion resistance) through the membrane increases. Depending on
the polymer
film used in the composite membrane, the vapor diffusion resistance may be
highly
dependent on the relative humidity of the air streams.
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SUMMARY OF THE DISCLOSURE
[0007] Certain embodiments of the present disclosure provide an energy
exchange assembly that may include one or more membrane panels. The one or
more
membrane panels may include a microporous membrane that has a pore size
between 0.02
and 0.3 micrometers (um) and a porosity between 45% and 80%.
[0008] Optionally, the energy exchange assembly may further include a
plurality
of spacers that define air channels. The air channels may be configured to
receive air
streams therethrough. Each of the one or more membrane panels may be disposed
between
two spacers. The one or more membrane panels may be configured to allow a
transfer of
sensible energy and latent energy across the one or more membrane panels
between the air
channels. Optionally, the pore size of the microporous membrane may be between
0.04 and
0.2 um. The porosity of the microporous membrane may be between 50% and 75%.
The
microporous membrane may have a vapor diffusion resistance below 40
seconds/meter
(sec/m) and an air permeability below 0.06 ft3/min/ft2.
[0009] Certain embodiments of the present disclosure provide an energy
exchange system that may include a supply air flow path configured to channel
supply air to
an enclosed structure, a regeneration air flow path configured to channel
regeneration air
from the enclosed structure to an outside environment, and an energy exchange
assembly
disposed within the supply air flow path and the regeneration air flow path.
The energy
exchange assembly may include a plurality of spacers and a plurality of
membrane panels.
Each membrane panel may include a microporous membrane that has a pore size
between
0.02 and 0.3 micrometers (pm) and a porosity between 45% and 80%. Each of the
spacers
may be positioned between two of the membrane panels to define air channels
through the
spacer between the two membrane panels. The air channels may be configured to
receive
air streams therethrough. The membrane panels may be configured to allow a
transfer of
sensible energy and latent energy across the membrane panels between the air
channels.
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BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Figure 1 illustrates a perspective top view of an energy
exchange
assembly, according to an embodiment of the present disclosure.
[0011] Figure 2 illustrates a perspective exploded top view of two
adjacent layers
of the energy exchange assembly shown in Figure 1, according to an embodiment
of the
present disclosure.
[0012] Figure 3 illustrates an end view of two adjacent layers of the
energy
exchange assembly shown in Figure 1, according to an embodiment of the present
disclosure.
[0013] Figure 4 illustrates a magnified microporous membrane of the
energy
exchange assembly shown in Figure 1, according to an embodiment of the present
disclosure.
[0014] Figure 5 illustrates a graph plotting vapor diffusion
resistance versus
mean relative humidity for comparison between three membranes.
[0015] Figure 6 illustrates a simplified schematic view of an energy
exchange
system operatively connected to an enclosed structure, according to an
embodiment of the
present disclosure.
[0016] Before the embodiments are explained in detail, it is to be
understood that
the disclosure is not limited in its application to the details of
construction and the
arrangement of the components set forth in the following description or
illustrated in the
drawings. The disclosure is capable of other embodiments and of being
practiced or being
carried out in various ways. Also, it is to be understood that the phraseology
and
terminology used herein are for the purpose of description and should not be
regarded as
limiting. The use of "including" and "comprising" and variations thereof is
meant to
encompass the items listed thereafter and equivalents thereof as well as
additional items and
equivalents thereof.
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DETAILED DESCRIPTION OF THE DISCLOSURE
[0017] The foregoing summary, as well as the following detailed
description of
certain embodiments will be better understood when read in conjunction with
the appended
drawings. As used herein, an element or step recited in the singular and
proceeded with the
word "a" or "an" should be understood as not excluding plural of the elements
or steps,
unless such exclusion is explicitly stated. Furthermore, references to "one
embodiment" are
not intended to be interpreted as excluding the existence of additional
embodiments that also
incorporate the recited features. Moreover, unless explicitly stated to the
contrary,
embodiments "comprising" or "having" an element or a plurality of elements
having a
particular property may include additional such elements not having that
property.
[0018] Figure 1 illustrates a perspective top view of an energy
exchange
assembly 10, according to an embodiment of the present disclosure. The energy
exchange
assembly 10 may be an energy recovery core, a plate heat exchanger, or the
like configured
to transfer energy between fluid streams, such as first and second air streams
12 and 14. As
such, the energy exchange assembly 10 may be an air-to-air energy recovery
core assembly.
[0019] The energy exchange assembly 10 may include a plurality of
microporous
membranes 16 separated by spacers 18. The membranes 16 may be formed of a
microporous material that is configured to allow sensible and latent energy to
pass
therebetween. The membranes 16 may be designed with a pore size and a porosity
that
achieves a desired balance of air permeability and vapor permeability. For
example, the
characteristics of the microporous membranes 16 may be designed to enhance the
transfer of
vapor across the membranes 16 while also reducing the air transfer across the
membranes 16.
By stacking the membranes 16 and the spacers 18, channels 19 are formed that
allow the
first and second air streams 12 and 14 to pass through the energy exchange
assembly 10.
[0020] The energy exchange assembly 10 may be oriented so that the
first air
stream 12 may be outside air that is to be conditioned, while the second air
stream 14 may
be exhaust, return, or scavenger air that is used to condition the outside air
before the outside
air is supplied to downstream HVAC equipment and/or an enclosed space as
supply air.
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Heat and moisture may be transferred between the first and second air streams
12 and 14
through the membranes 16 within the energy exchange assembly 10.
[0021] The microporous membranes 16 and spacers 18 may be secured
between
outer upstanding brackets 20, a base 22, and a top wall 24. As shown, the
brackets 20 may
generally be at the corners of the energy exchange assembly 10. The base 22,
the top wall
24, and the brackets 20 provide a main housing defining an internal chamber
into which the
membranes 16 and the spacers 18 are secured.
[0022] The energy exchange assembly 10 may include a plurality of
layers or
levels 26 which are vertically stacked along an elevation axis z. Each layer
26 may include
a spacer 18 positioned between two microporous membranes 16. One membrane 16
may be
below the spacer 18, while the other membrane 16 in the layer 26 is disposed
above the
spacer 18. In an embodiment, the spacers 18 and membranes 16 are stacked in an
alternating pattern such that only one membrane 16 separates adjacent spacers
18. Thus,
adjacent layers 26A, 26B may share one membrane 16. The spacers 18 in adjacent
layers
26A, 26B may be oriented orthogonally to each other such that the air channels
19 through
the spacers 18 channel the air in different directions. For example, the air
channels 19 in the
layers 26A may be oriented parallel to an axis y, while the air channels 19 in
the layers 26B
may be oriented parallel to an axis x, which is perpendicular (or oriented at
an acute angle)
to the axis y. Thus, the levels 26A may be oriented to receive the second air
stream 14 at an
inlet side 30 and direct the second air stream 14 to an outlet side 31, while
the levels 2613
may be oriented to receive the first air stream 12 at an inlet side 32, which
is perpendicular
to the inlet side 30, and direct the first air stream 12 to an outlet side 33,
which is
perpendicular to the outlet side 31. Therefore, the air stream 14, passing
through the levels
26A, travels in a cross-flow direction with the air stream 12 passing through
the levels 26B.
In this manner, sensible and/or latent energy may be exchanged between the
levels 26A and
26B.
[0023] For example, as shown in Figure 1, the first air stream 12 may
enter the
inlet side 32 as cool, dry air. As the first air stream 12 passes through the
energy exchange
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assembly 10, the temperature and humidity of the first stream 12 are both
increased through
energy transfer with the second air stream 14 that enters the energy exchange
assembly 10
through the inlet side 30 as warm, moist air. Accordingly, the first air
stream 12 passes out
of the outlet side 33 as warmer, moister air (as compared to the first air
stream 12 before
passing into the inlet side 32), while the second air stream 14 passes out of
the outlet side 31
as cooler, drier air (as compared to the second air stream 14 before passing
into the inlet side
30). In general, the temperature and humidity of the first and second air
streams 12 and 14
passing through the levels 26A and 26B tends to at least partially equilibrate
with one
another. For example, warm, moist air within the levels 26A is cooled and
dried by heat
exchange with the cooler, drier air in the levels 26B. Cool, dry air within
the levels 26B is
warmed and moistened by the warmer, cooler air within the levels 26A. As a
result, the
second air stream 14 that passes through the levels 26A may be cooler and
drier after
passing through the energy exchange assembly 10. Conversely, the first air
stream 12 that
passes through the levels 26B may be warmer and moister after passing through
the energy
exchange assembly 10.
[0024] Figure 2 illustrates a perspective exploded top view of two
adjacent layers
26 of the energy exchange assembly 10 shown in Figure 1, according to an
embodiment of
the present disclosure. The layers 26 include alternating spacers 18 and
microporous
membranes 16, which are stacked on top of each other in a layer stack 202. The
microporous membranes 16 may form a part of membrane panels 206, which are
alternatively stacked with the spacers 18. The membrane panels 206 may each
include a
sheet of the microporous membrane 16 and an outer frame 208 to which the
membrane 16 is
attached, disposed, or integrated. The outer frame 208 may be a plastic or
other polymer
frame that retains the microporous membrane 16 in a stretched or at least
tight configuration
within an inner space (not shown) defined by the frame 208. The frame 208 may
engage the
spacers 18 when assembling the layer stack 202. In an alternative embodiment,
the
membrane panels 206 do not include an outer frame 208.
[0025] The microporous membranes 16 may include thin, porous sheets
composed of expanded polytetrafluoroethylene (ePTFE), polypropylene (PP),
nylon,
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polyvinylidene fluoride (PVDF), polyethersulfone (PES), combinations thereof,
or the like.
The membranes 16 may be hydrophobic or hydrophilic (for example, if composed
of nylon).
The membranes 16 optionally may be manufactured by a dry stretch process, a
wet stretch
process, or another process. In at least one embodiment, the membrane panels
206 may
include a backing layer (not shown in Figure 2) that is bonded to the
microporous membrane
16 to provide structural support to the membrane 16. The backing layer may be
a spunbond
non-woven or a non-woven mesh. The backing layer may be made from materials
including
polypropylene (PP), polyethylene (PE), polyester, nylon, fiberglass, and/or
the like. The
backing layer of the membrane panel 206 provides support to the microporous
membrane 16,
making the membrane 16 stiffer and more durable. In at least one embodiment,
each
backing layer is bonded to a single sheet or layer of the microporous membrane
16 to form
each membrane panel 206.
[0026] The spacers 18 may be formed of plastic, metal, or the like. As
shown in
Figure 2, the spacers 18 include walls 210 that are aligned parallel to each
other, and
connecting cross-bars 212 that structurally support the walls 210. The air
channels 19 are
formed between adjacent walls 210 and extend along the length of the walls
210. For
example, the walls 210 may engage the membrane panels 206 above and below the
spacer
18. The height of the walls 210 may define the height of the channels 19. The
cross-bars
212 may have a small height relative to the walls 210 to prohibit the cross-
bars 212 from
impeding the flow of air through the channels 19. In alternative embodiments,
the spacers
18 may have various other sizes and shapes. For example, the spacers may be
corrugated
with curved, undulating walls or saw tooth angled walls instead of upstanding
walls.
[0027] During assembly of the layer stack 202, a lower spacer 18A is
mounted
on top of a lower membrane panel 206A. A middle membrane panel 206B is
subsequently
mounted on top of the spacer 18A. An upper spacer 18B is then mounted on the
middle
membrane panel 206B, and an upper membrane panel 206C is mounted on the upper
spacer
18B. As used herein, relative or spatial terms such as "top," "bottom,"
"upper," "lower,"
and "middle" are only used to distinguish the referenced elements and do not
necessarily
require particular positions or orientations in the energy exchange assembly
10 (shown in
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Figure 10) or in the surrounding environment of the energy exchange assembly
10. The
stacking pattern may continue to produce an energy exchange assembly 10 of a
desired
height. In an embodiment, the upper spacer 18B is rotated 90 relative to the
lower spacer
18A. Consequently, the channels 19 through the spacer 18A are orthogonal to
the channels
19 through the spacer 18B, so that air flows through the channels 19 of the
adjacent layers
26A, 26B in a cross-flow direction. Alternatively, the membranes 16 and the
spacers 18
may be arranged to support various other air flow orientations, such as
counter-flow,
concurrent flow, and the like.
[0028] Figure 3 illustrates an end view of two adjacent layers 26 of
the layer
stack 202 (shown in Figure 2) according to an embodiment of the present
disclosure. The
two layers 26 include three membrane panels 206 and two spacers 18 that
separate the
panels 206. The spacers 18 may each include upstanding parallel walls 210 that
define air
channels 19 therebetween. For example, the spacers 18 may be oriented
orthogonally to
each other such that the walls 210 of the upper spacer 18B are oriented
perpendicularly to
the walls 210 of the lower spacer 18A. Air flow is configured to flow in the
directions 220
and 222 through the air channels 19 between the membrane panels 206. Direction
220 is
shown to extend into the page, and direction 222 is shown to extend towards
the right.
Optionally, the directions 220, 222 may be reversed. The first air stream 12
(shown in
Figure 1) may be configured to flow in the direction 222, and the second air
stream 14
(Figure 1) may be configured to flow in the direction 220. Sensible and latent
energy may
be transferred to or from the air streams in the direction of arrows 224
through the
membrane panels 206. The membrane panels 206 include a microporous membrane
(shown
in Figure 2) that is designed to maximize the amount of vapor that transfers
across the
membrane panels 206 while minimizing the transfer of air across the panels
206.
[0029] Figure 4 illustrates a magnified microporous membrane 16 of the
energy
exchange assembly 10 shown in Figure 1, according to an embodiment. In order
to balance
the air permeability with vapor permeability (for example, vapor diffusion
resistance), the
microporous membrane 16 may have a specific range of characteristics. For
example, the
microporous membrane 16 may include various pores 402 that extend through the
thin
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membranes 16. The pores 402 may have a pore size or diameter 404 that is less
than 0.5
micrometers (um). In an embodiment, the pore size 404 of the pores 402 is
between 0.01
and 0.4 um. As used herein, the term "between" that introduces a range of
values means
"between and including" such that the range includes the listed end values.
More
specifically, the pore size 404 may be between 0.02 and 0.3 Jim. More
specifically, the pore
size 404 may be between 0.04 and 0.2 JIM, or more specifically between 0.06
and 0.1 um.
The pore size 404 and/or range of sizes is selected to reduce the vapor
diffusion resistance of
the membrane 16 to allow vapor transfer while also sufficiently reducing air
permeability
through the membrane 16. In an embodiment, the shape of the pores 402 is not
limited. For
example, the pores 402 may be elliptical, as shown in Figure 4, or may be
rectangular,
circular, or the like.
[0030] The microporous membrane 16 may have a porosity between 40% and
80%. The porosity is the fraction or percentage of voids or empty spaces
within a material.
In an embodiment, the porosity of the microporous membrane 16 may be between
45% and
80%. More specifically, the porosity may be between 50% and 75%, or more
specifically
between 55% and 70%.
[0031] In an embodiment, the microporous membrane 16 may have a
membrane
vapor diffusion resistance below 50 second/meters (sec/m) (measured using the
DMPC
method with the inlet air streams set to 5% relative humidity (RH) and 95% RH)
and an air
permeability below 0.08 ft3/min/ft2 (0.041 cm3/sec/cm2) at 0.5 inches of water
(inH20)
(based on ASTM D737) (approximately 125 Pa). More specifically, the membrane
vapor
diffusion resistance may be below 40 sec/m and the air permeability below 0.06
ft3/min/ft2
(0.03 cm3/sec/cm2) at 0.5 inH20. For example, the membrane vapor diffusion
resistance
may be below 35 sec/m and the air permeability below 0.0574 ft3/min/ft2 (0.029
cm3/sec/cm2) at 0.5 inH20.
[0032] Referring now back to Figure 2, the thickness of the
microporous
membrane 16 also affects the rigidity and moisture vapor transfer rate (MVTR),
which is
directly related to the vapor diffusion resistance. For example, the rigidity
of the membrane
16 increases by selecting a thicker material with the same pore size and
porosity. However
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increasing the thickness of the membrane 16 reduces the MVTR. Therefore, the
thickness
may be selected to achieve a balance between rigidity and MVTR. The thickness
of the
membrane 16 may be reduced while preserving rigidity by laminating the
membrane 16 onto
the backing layer (not shown). For example, the thickness of the membrane 16
may be less
than 50 gm, such as between 10 and 40 gm. More specifically, the thickness of
the
membrane 16 may be between 15 and 40 gm. When the membrane 16 is bonded to the
backing layer, the thickness of the membrane panel 206 may be between 100 and
400 gm,
such as between 200 and 300 gm. The backing layer may have higher pore sizes
and
porosities relative to the microporous membrane 16, so the backing layer does
not
significantly affect (for example, has only a negligible impact on) vapor
transmission and/or
air transmission through the membrane panel 206. In at least one embodiment,
the backing
layer and the membrane 16 have a combined stiffness (defined as the product of
the modulus
of elasticity and the material thickness) above 15 MPa=rnm. More specifically,
the stiffness
may be above 25 MPa=mm.
[0033] As an example, a microporous membrane for use in an air-to-air
energy
recovery core may be made out of polypropylene, with a pore size of 0.06 gm, a
porosity of
55%, and a thickness of 25 gm, and may be bonded it to a polyethylene mesh
backing. The
resulting membrane may have a vapor diffusion resistance of 28 sec/m, airflow
permeability
of 0.0146 ft3/min/ft2 (0.0074 cm3/sec/cm2) at 0.5 inches of water (inH20)
(approximately
125 Pa), and a stiffness of 55 MPa=mm. When the resulting membrane is used in
the
membrane panels of an energy exchange core having a size of 21 in. x 21 in. x
18.625 in.
(53.3 cm x 53.3 cm x 47.3 cm) and a channel thickness of 3.5 mm, the resulting
performance of the energy exchange core is a total effectiveness of 55% and an
Outdoor Air
Correction Factor of 1.07 at a differential pressure of 5 inH20 (based on
ASHRAE Standard
84) (approximately 1.244 kPa).
[0034] As another example, a microporous membrane for use in an air-to-
air
energy recovery core may be formed of polypropylene, having a pore size of 0.1
gm, a
porosity of 67%, and a thickness of 20 gm, and is bonded it to a 3.0 oz.
(approximately 85 g)
polypropylene spunbond non-woven backing. The resulting membrane has a vapor
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diffusion resistance of 17 sec/m, airflow permeability of 0.0382 ft3/mingt2
(0.019
cm3/sec/cm2) at 0.5 inH20, and a stiffness of 27 MPa=mm. When the resulting
membrane is
used in the same energy exchange assembly of size 21 in. x 21 in. x 18.625 in.
(53.3 cm x
53.3 cm x 47.3 cm) with a channel thickness of 3.5 mm, the resulting
performance is a total
effectiveness of 60% and an Outdoor Air Correction Factor of 1.07 at a
differential pressure
of 2 inH20 (based on ASHRAE Standard 84) (approximately 250 Pa).
[0035] Figure 5 illustrates a graph 500 plotting vapor diffusion
resistance versus
mean relative humidity for comparison between three membranes. The graph 500
compares
a microporous membrane 502, as described herein, to other known membranes,
including a
non-porous hygroscopic membrane 504 and a composite polymer membrane 506. As
shown
in Figure 5, the microporous membrane 502 may have less vapor diffusion
resistance than
both the non-porous hygroscopic membrane 504 and the composite polymer
membrane 506.
In addition, the microporous membrane 502 may have a low (or even negligible)
dependency on humidity, as shown by the relative lack of a slope 508 in the
trend line for
the microporous membrane 502. The vapor diffusion resistance of the other two
membranes
504, 506 may be at least moderately dependent on humidity.
[0036] As seen in Figure 5, the disadvantage of the non-porous
hygroscopic
membrane 504 is that the ability for the membrane to transfer moisture is
highly dependent
on the relative humidity of the air. In a very humid environment, hygroscopic
membranes
have a low vapor diffusion resistance, while in a low humidity environment,
the membranes
have a high vapor diffusion resistance. This characteristic is shown by the
drastic slope 510
in Figure 5 as the humidity increases.
[0037] One of the primary disadvantages of the composite polymer
membrane
506 is that by adding and bonding multiple polymer layers together, the
resistance to
moisture transfer through the membrane increases. Thus, as shown in Figure 5,
the vapor
diffusion resistance is significantly higher than that of the microporous
membrane 502.
Depending on the polymer film used in the composite membrane 506, the vapor
diffusion
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resistance may also be at least moderately dependent on the relative humidity
of the air, as
seen in Figure 5 by the negative slope 512 of the trend line for the composite
membrane 506.
[0038] In addition, although not shown in Figure 5, manufacturing the
microporous membrane as a single layer membrane with a supporting backing
layer may be
cheaper to produce than typical multi-layer membranes. The typical multi-layer
membranes
either incorporate a hydrophobic or hydrophilic coating or an additional
second membrane
layer in order to achieve low water vapor diffusion resistance and low air
permeability. In
an exemplary embodiment, the microporous membrane does not include any
additional
coating or layer, excluding the support backing which does not affect vapor
diffusion or air
permeability.
[0039] Figure 6 illustrates a simplified schematic view of an energy
exchange
system 300 operatively connected to an enclosed structure 302, according to an
embodiment
of the present disclosure. The energy exchange system 300 may include a
housing 304, such
as a self-contained module or unit that may be mobile (for example, the
housing 304 may be
moved among a plurality of enclosed structures), operatively connected to the
enclosed
structure 302, such as through a connection line 306, such as a duct, tube,
pipe, conduit,
plenum, or the like. The housing 304 may be configured to be removably
connected to the
enclosed structure 302. Alternatively, the housing 304 may be permanently
secured to the
enclosed structure 302. As an example, the housing 304 may be mounted to a
roof, outer
wall, or the like, of the enclosed structure 302. The enclosed structure 302
may be a room of
a building, a commodities storage structure, or the like.
[0040] The housing 304 includes a supply air inlet 308 that connects
to a supply
air flow path 310. The supply air flow path 310 may be formed by ducts,
conduits, plenum,
channels, tubes, or the like, which may be formed by metal and/or plastic
walls. The supply
air flow path 310 is configured to deliver supply air 312 to the enclosed
structure 302
through a supply air outlet 314 that connects to the connection line 306. The
supply air 312
may be received in the supply air flow path 310 from the atmosphere (for
example, an
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outside environment). Alternatively, the supply air 312 may be received from
the enclosed
structure 302 as return supply air.
[0041] The housing 304 also includes a regeneration air inlet 316 that
connects
to a regeneration air flow path 318. The regeneration air flow path 318 may be
formed by
ducts, conduits, plenum, tubes, or the like, which may be formed by metal
and/or plastic
walls. The regeneration air flow path 318 is configured to channel
regeneration air 320
received from the enclosed structure 302 to the atmosphere (for example, an
outside
environment) through an exhaust air outlet 322. Alternatively, the
regeneration air 320 may
be received from the atmosphere and channeled back to the atmosphere through
the exhaust
air outlet 322.
[0042] As shown in Figure 6, the supply air inlet 308 and the
regeneration air
inlet 316 may be longitudinally aligned. For example, the supply air inlet 308
and the
regeneration air inlet 316 may be at opposite ends of a linear column or row
of ductwork. A
separating wall 324 may separate the supply air flow path 310 from the
regeneration air flow
path 318 within the column or row. Similarly, the supply air outlet 314 and
the exhaust air
outlet 322 may be longitudinally aligned. For example, the supply air outlet
314 and the
exhaust air outlet 322 may be at opposite ends of a linear column or row of
ductwork. A
separating wall 326 may separate the supply air flow path 310 from the
regeneration air flow
path 318 within the column or row.
[0043] The supply air inlet 308 may be positioned above the exhaust
air outlet
322, and the supply air flow path 310 may be separated from the regeneration
air flow path
318 by a partition 328. Similarly, the regeneration air inlet 316 may be
positioned above the
supply air outlet 314, and the supply air flow path 310 may be separated from
the
regeneration air flow path 318 by a partition 330. Thus, the supply air flow
path 310 and the
regeneration air flow path 318 may cross one another proximate to a center of
the housing
304. While the supply air inlet 308 may be at the top and left of the housing
304, the supply
air outlet 314 may be at the bottom and right of the housing 304. Further,
while the
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regeneration air inlet 316 may be at the top and right of the housing 304, the
exhaust air
outlet 322 may be at the bottom and left of the housing 304.
[0044] Alternatively, the supply air flow path 310 and the
regeneration air flow
path 318 may be inverted and/or otherwise re-positioned. For example, the
exhaust air
outlet 322 may be positioned above the supply air inlet 308. Additionally,
alternatively, the
supply air flow path 310 and the regeneration air flow path 318 may be
separated from one
another by more than the separating walls 324 and 326 and the partitions 328
and 330 within
the housing 304. For example, spaces, which may contain insulation, may also
be
positioned between segments of the supply air flow path 310 and the
regeneration air flow
path 318. Also, alternatively, the supply air flow path 310 and the
regeneration air flow path
318 may simply be straight, linear segments that do not cross one another.
Further, instead
of being stacked, the housing 304 may be shifted 90 degrees about a
longitudinal axis
aligned with the partitions 328 and 330, such that that supply air flow path
310 and the
regeneration air flow path 318 are side-by-side, instead of one on top of
another.
[0045] An air filter 332 may be disposed within the supply air flow
path 310
proximate to the supply air inlet 308. The air filter 332 may be a standard
HVAC filter
configured to filter contaminants from the supply air 312. Alternatively, the
energy
exchange system 300 may not include the air filter 332.
[0046] An energy transfer device 334 may be positioned within the
supply air
flow path 310 downstream from the supply air inlet 308. The energy transfer
device 334
may span between the supply air flow path 310 and the regeneration air flow
path 318. For
example, a supply portion or side 335 of the energy transfer device 334 may be
within the
supply air flow path 310, while a regenerating portion or side 337 of the
energy transfer
device 334 may be within the regeneration air flow path 318. In an alternative
embodiment,
the energy transfer device 334 or an additional energy transfer device may be
disposed
within the supply air flow path 310 downstream of the energy exchange assembly
336 and
within the regeneration air flow path 318 upstream of the energy exchange
assembly 336 in
order to provide energy transfer between the supply air 312 and the
regeneration air 320.
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The energy transfer device 334 may be a desiccant wheel, a heat pipe, or a
heat plate, for
example. However, the energy transfer device 334 may be various other systems
and
assemblies, such as including liquid-to-air membrane energy exchangers
(LAMEEs), as
described below.
[0047] An energy exchange assembly 336, which may be formed as
described
above with respect to Figures 5-16, is disposed within the supply air flow
path 310
downstream from the energy transfer device 334. The energy exchange assembly
336 may
be positioned at the junction of the separating walls 324, 326 and the
partitions 328, 330.
The energy exchange assembly 336 may be positioned within both the supply air
flow path
310 and the regeneration air flow path 318. As such, the energy exchange
assembly 336 is
configured to transfer energy between the supply air 312 and the regeneration
air 320.
[0048] One or more fans 338 may be positioned within the supply air
flow path
310 downstream from the energy exchange assembly 336. The fan(s) 338 is
configured to
move the supply air 312 from the supply air inlet 308 and out through the
supply air outlet
314 (and ultimately into the enclosed structure 302). Alternatively, the
fan(s) 338 may be
located at various other areas of the supply air flow path 310, such as
proximate to the
supply air inlet 308. Also, alternatively, the energy exchange system 300 may
not include
the fan(s).
[0049] The energy exchange system 300 may also include a bypass duct
340
having an inlet end 342 upstream from the energy transfer device 334 within
the supply air
flow path 310. The inlet end 342 connects to an outlet end 344 that is
downstream from the
energy transfer device 334 within the supply air flow path 310. An inlet
damper 346 may be
positioned at the inlet end 342, while an outlet damper 348 may be positioned
at the outlet
end 344. The dampers 346 and 348 may be actuated between open and closed
positions to
provide a bypass line for the supply air 312 to bypass around the energy
transfer device 334.
Further, a damper 350 may be disposed within the supply air flow path 310
downstream
from the inlet end 342 and upstream from the energy transfer device 334. The
damper 350
may be closed in order to allow the supply air 312 to flow into the bypass
duct 340 around
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the energy transfer device 334. The dampers 346, 348, and 350 may be modulated
between
fully-open and fully-closed positions to allow a portion of the supply air 312
to pass through
the energy transfer device 334 and a remaining portion of the supply air 312
to bypass the
energy transfer device 334. As such, the bypass dampers 346, 348, and 350 may
be
operated to control the temperature and humidity of the supply air 312 as it
is delivered to
the enclosed structure 302. Examples of bypass ducts and dampers are further
described in
United States Patent Application No. 13/426,793, entitled "System and Method
For
Conditioning Air In An Enclosed Structure," which was filed March 22, 2012,
and is hereby
incorporated by reference in its entirety. Alternatively, the energy exchange
system 300
may not include the bypass duct 340 and dampers 346, 348, and 350.
[0050] As shown in Figure 6, the supply air 312 enters the supply air
flow path
310 through the supply air inlet 308. The supply air 312 is then channeled
through the
energy transfer device 334, which pre-conditions the supply air 312. After
passing through
the energy transfer device 334, the supply air 312 is pre-conditioned and
passes through the
energy exchange assembly 336, which conditions the pre-conditioned supply air
312. The
fan(s) 338 may then move the supply air 312, which has been conditioned by the
energy
exchange assembly 336, through the energy exchange assembly 336 and into the
enclosed
structure 302 through the supply air outlet 314.
[0051] With respect to the regeneration air flow path 318, an air
filter 352 may
be disposed within the regeneration air flow path 318 proximate to the
regeneration air inlet
316. The air filter 352 may be a standard HVAC filter configured to filter
contaminants
from the regeneration air 320. Alternatively, the energy exchange system 300
may not
include the air filter 352.
[0052] The energy exchange assembly 336 may be disposed within the
regeneration air flow path 318 downstream from the air filter 352. The energy
exchange
assembly 336 may be positioned within both the supply air flow path 310 and
the
regeneration air flow path 318. As such, the energy exchange assembly 336 is
configured to
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transfer sensible energy and latent energy between the regeneration air 320
and the supply
air 312.
[0053] A heater 354 may be disposed within the regeneration air flow
path 318
downstream from the energy exchange assembly 336. The heater 354 may be a
natural gas,
propane, or electric heater that is configured to heat the regeneration air
320 before it
encounters the energy transfer device 334. Optionally, the energy exchange
system 300 may
not include the heater 354.
[0054] The energy transfer device 334 is positioned within the
regeneration air
flow path 318 downstream from the heater 354. As noted, the energy transfer
device 334
may span between the regeneration air flow path 318 and the supply air flow
path 310.
[0055] As shown in Figure 6, the supply side 335 of the energy
transfer device
334 is disposed within the supply air flow path 310 proximate to the supply
air inlet 308,
while the regeneration side 337 of the energy transfer device 334 is disposed
within the
regeneration air flow path 310 proximate to the exhaust air outlet 322.
Accordingly, the
supply air 312 encounters the supply side 335 as the supply air 312 enters the
supply air
flow path 310 from the outside, while the regeneration air 320 encounters the
regeneration
side 337 just before the regeneration air 320 is exhausted out of the
regeneration air flow
path 318 through the exhaust air outlet 322.
[0056] One or more fans 356 may be positioned within the regeneration
air flow
path 318 downstream from the energy transfer device 334. The fan(s) 356 is
configured to
move the regeneration air 320 from the regeneration air inlet 316 and out
through the
exhaust air outlet 322 (and ultimately into the atmosphere). Alternatively,
the fan(s) 356
may be located at various other areas of the regeneration air flow path 318,
such as
proximate to the regeneration air inlet 316. Also, alternatively, the energy
exchange system
300 may not include the fan(s).
[0057] The energy exchange system 300 may also include a bypass duct
358
having an inlet end 360 upstream from the energy transfer device 334 within
the
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regeneration air flow path 318. The inlet end 360 connects to an outlet end
362 that is
downstream from the energy transfer device 334 within the regeneration air
flow path 318.
An inlet damper 364 may be positioned at the inlet end 360, while an outlet
damper 366 may
be positioned at the outlet end 362. The dampers 364 and 366 may be actuated
between
open and closed positions to provide a bypass line for the regeneration air
320 to flow
around the energy transfer device 334. Further, a damper 368 may be disposed
within the
regeneration air flow path 318 downstream from the heater 354 and upstream
from the
energy transfer device 334. The damper 368 may be closed in order to allow the
regeneration air to bypass into the bypass duct 358 around the energy transfer
device 334.
The dampers 364, 366, and 368 may be modulated between fully-open and fully-
closed
positions to allow a portion of the regeneration air 320 to pass through the
energy transfer
device 334 and a remaining portion of the regeneration air 320 to bypass the
energy transfer
device 334. Alternatively, the energy exchange system 300 may not include the
bypass duct
358 and dampers 364 and 166.
[0058] As shown in Figure 6, the regeneration air 320 enters the
regeneration air
flow path 318 through the regeneration air inlet 316. The regeneration air 320
is then
channeled through the energy exchange assembly 336. After passing through the
energy
exchange assembly 336, the regeneration air 320 passes through the heater 354,
where it is
heated, before encountering the energy transfer device 334. The fan(s) 356 may
then move
the regeneration air 320 through the energy transfer device 334 and into the
atmosphere
through the exhaust air outlet 322.
[0059] As described above, the energy exchange assembly 336, which may
be
formed according to any of the methods described above, may be used with
respect to the
energy exchange system 300. Optionally, the energy exchange assembly 336 may
be used
with various other systems that are configured to condition outside air and
supply the
conditioned air as supply air to an enclosed structure, for example. The
energy exchange
assembly 336 may be positioned within a supply air flow path, such as the path
310, and a
regeneration or exhaust air flow path, such as the path 318, of a housing,
such as the housing
304. The energy exchange system 300 may include only the energy exchange
assembly 336
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within the paths 310 and 318 of the housing 304, or may alternatively include
any of the
additional components shown and described with respect to Figure 6.
[0060] Embodiments of the present disclosure provide an energy
exchange
assembly, such as an energy recovery core, that utilizes a microporous
membrane in
membrane panels to increase the latent effectiveness of the assembly. The
membrane panels
may not require a hydrophilic layer or multiple composite layers, other than a
structural
backing layer which may be added for support. The microporous membrane may not
be
significantly dependent on the relative humidity of the air, which allows the
energy
exchange assembly to have a similar effectiveness in a hot, humid climate and
a cool, dry
climate. The microporous membrane may include many pores, which allow water
vapor
through the membrane. The pore size of the pores may be designed to increase
the water
vapor transfer rate and reduce the vapor diffusion resistance. Some air may
also pass
through the pores across the membrane, but the amount of airflow may be
maintained at an
acceptable level by optimizing the properties of the membrane. For example,
the properties
of the microporous membrane, such as pore size and porosity, may be designed
to achieve a
balance between optimizing vapor transfer while maintaining acceptable air
leakage.
[0061] It is to be understood that the above description is intended
to be
illustrative, and not restrictive. For example, the above-described
embodiments (and/or
aspects thereof) may be used in combination with each other. In addition, many
modifications may be made to adapt a particular situation or material to the
teachings of the
various embodiments of the disclosure without departing from their scope.
While the
dimensions and types of materials described herein are intended to define the
parameters of
the various embodiments of the disclosure, the embodiments are by no means
limiting and
are exemplary embodiments. Many other embodiments will be apparent to those of
skill in
the art upon reviewing the above description. The scope of the various
embodiments of the
disclosure should, therefore, be determined with reference to the appended
claims, along
with the full scope of equivalents to which such claims are entitled. In the
appended claims,
the terms "including" and "in which" are used as the plain-English equivalents
of the
respective terms "comprising" and "wherein." Moreover, the terms "first,"
"second," and
CA 02901492 2015-08-17
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"third," etc. are used merely as labels, and are not intended to impose
numerical
requirements on their objects. Further, the limitations of the following
claims are not
written in means-plus-function format and are not intended to be interpreted
based on 35
U.S.C. 112(f), unless and until such claim limitations expressly use the
phrase "means for"
followed by a statement of function void of further structure.
[0062] This written description uses examples to disclose the various
embodiments of the disclosure, including the best mode, and also to enable any
person
skilled in the art to practice the various embodiments of the disclosure,
including making
and using any devices or systems and performing any incorporated methods. The
patentable
scope of the various embodiments of the disclosure is defined by the claims,
and may
include other examples that occur to those skilled in the art. Such other
examples are
intended to be within the scope of the claims if the examples have structural
elements that
do not differ from the literal language of the claims, or if the examples
include equivalent
structural elements with insubstantial differences from the literal languages
of the claims.
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