U.S. patent application number 16/392848 was filed with the patent office on 2019-09-19 for counter-flow energy recovery ventilator (erv) core.
The applicant listed for this patent is CORE Energy Recovery Solutions Inc.. Invention is credited to Jordan Benda BALANKO, James Franklin DEAN, Ryan Nicholas HUIZING, David Erwin KADYLAK, Curtis Warren MULLEN.
Application Number | 20190285289 16/392848 |
Document ID | / |
Family ID | 48667581 |
Filed Date | 2019-09-19 |
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United States Patent
Application |
20190285289 |
Kind Code |
A1 |
DEAN; James Franklin ; et
al. |
September 19, 2019 |
COUNTER-FLOW ENERGY RECOVERY VENTILATOR (ERV) CORE
Abstract
A heat and humidity exchanger has example application in
exchanging heat and water vapor between fresh air entering a
building and air being vented from the building. The heat and
humidity exchanger has a self-supporting core formed from layered
sheets of a moisture-permeable material. Plenums are arranged to
direct fluid streams into and out of the core. The plenums may be
on opposing sides of the core to permit counterflow exchange of
heat and water vapor.
Inventors: |
DEAN; James Franklin; (West
Vancouver, CA) ; KADYLAK; David Erwin; (Surrey,
CA) ; HUIZING; Ryan Nicholas; (Vancouver, CA)
; BALANKO; Jordan Benda; (West Vancouver, CA) ;
MULLEN; Curtis Warren; (Vancouver, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CORE Energy Recovery Solutions Inc. |
Vancouver |
|
CA |
|
|
Family ID: |
48667581 |
Appl. No.: |
16/392848 |
Filed: |
April 24, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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15184757 |
Jun 16, 2016 |
10317095 |
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16392848 |
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14360245 |
May 22, 2014 |
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PCT/CA2012/050918 |
Dec 19, 2012 |
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15184757 |
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61577209 |
Dec 19, 2011 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
Y02B 30/56 20130101;
F28D 21/0015 20130101; F28F 2275/025 20130101; F28D 9/0025
20130101; Y02B 30/563 20130101; F28F 9/0268 20130101; F28F 9/26
20130101; F28D 9/0037 20130101; F24F 2012/008 20130101; F24F
2003/1435 20130101; F24F 11/46 20180101; F24F 3/147 20130101 |
International
Class: |
F24F 3/147 20060101
F24F003/147; F28F 9/02 20060101 F28F009/02; F28D 21/00 20060101
F28D021/00; F28D 9/00 20060101 F28D009/00; F28F 9/26 20060101
F28F009/26 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 7, 2012 |
CA |
PCT/CA2012/000560 |
Claims
1. A heat and humidity exchanger core comprising: a plurality of
water vapor-permeable layers stacked and joined together; at least
some of the water vapor-permeable layers comprising molded sheets,
the molded sheets comprising a sheet of a composite material
comprising a porous formable support layer and an air-impermeable
and water-vapor-permeable coating supported by the support layer
wherein the sheet of composite material is formed to include
out-of-plane features, the molded sheet having a central section
and first and second manifold regions, the out-of-plane features in
the central section configured to, together with adjacent ones of
the layers of the core, define a first plurality of channels
extending between the first and second manifold regions on a first
face of the molded sheet and a second plurality of channels
extending between the first and second manifold regions on a second
first face of the molded sheet opposed to the first face when the
molded sheet is stacked between the adjacent ones of the layers of
the core, the channels of the first and second pluralities of
channels having heights of at least 2 mm, the heights of the
plurality of channels determined at least in part by dimensions of
the out-of-plane features of the central section, an inlet plenum
and an outlet plenum between each adjacent pair of the stacked
layers, the inlet plenum defined at least in part by the first
manifold region of one of the stacked molded sheets, and the outlet
plenum defined at least in part by the second manifold region of
the one of the stacked molded sheets, the plurality of channels
fluidly connecting the inlet plenum to the outlet plenum, the
manifold regions configured such that the inlet and outlet plenums
each fluidly connect the first plurality of channels, the inlet
plenum is arranged to direct a first flow into the plurality of
channels at one side of the central section and the outlet plenum
is arranged to receive the first flow on the other side of the
central section.
2. The heat and humidity exchanger core of claim 1 wherein the
molded sheets are hexagonal, the central section of each molded
sheet is rectangular and extends between opposing edges of the
hexagonal sheet, and the first and second manifold regions of each
molded sheet are triangular.
3. The heat and humidity exchanger core of claim 1 wherein each of
the plurality of water vapor-permeable layers comprises one of the
molded sheets.
4. The heat and humidity exchanger core of claim 3 wherein each of
the plurality of channels is defined between the central sections
of an adjacent pair of the stacked molded sheets and each of the
plurality of channels is quadrilateral in cross-section.
5. The heat and humidity exchanger core of claim 3 wherein each of
the plurality of channels defined by the central sections of
adjacent pairs of stacked molded sheets is rectangular in
cross-section and the channels have widths of at least 2 mm.
6. The heat and humidity exchanger core of claim 1 wherein the
molded sheets make up alternate ones of the stacked layers and flat
water-vapor-permeable sheets make up alternate ones of the stacked
layers.
7. The heat and humidity exchanger core of claim 6 wherein each of
the plurality of channels is defined between the central section of
one of the molded sheets and a flat surface of one of the flat
sheets and the channels of the plurality of channels are triangular
in cross-section.
8. The heat and humidity exchanger core of claim 6 wherein the flat
sheets are made from the same material as the molded water
vapor-permeable sheets.
9. The heat and humidity exchanger core of claim 1 wherein the
support layer of the molded water vapor-permeable sheets comprises
a non-woven fabric and the molded water vapor-permeable sheets
comprise a nanofibrous layer on the nonwoven fabric.
10. The heat and humidity exchanger core of claim 1 wherein the
molded sheets are formed to provide out-of-plane features in the
first and second manifold regions.
11. The heat and humidity exchanger core of claim 10 wherein the
out-of-plane features in each of the first and second manifold
regions comprise walls defining a periphery of a corresponding one
of the plenums.
12. The heat and humidity exchanger core of claim 10 wherein the
out-of-plane features in the first and second manifold regions
comprise a plurality of ribs formed in each of the first and second
manifold regions.
13. The heat and humidity exchanger core of claim 1 wherein the
core is potted with a sealant material on at least two faces of the
core, whereby adjacent ones of the stacked layers are joined
together by the sealant material.
14. The heat and humidity exchanger core of claim 1 wherein the
molded sheets are stamped.
15. The heat and humidity exchanger core of claim 1 wherein the
central sections of the molded sheets are formed to provide
parallel corrugations.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. application Ser.
No. 15/184757 filed 16 Jun. 2016, which is a continuation of U.S.
application Ser. No. 14/360245 filed 22 May 2014 entitled
COUNTER-FLOW ENERGY RECOVERY VENTILATOR (ERV) CORE, which is a 371
of PCT International Application No. PCT/CA2012/050918 filed 19
Dec. 2012 entitled COUNTER-FLOW ENERGY RECOVERY VENTILATOR (ERV)
CORE, which claims the benefit under 35 U.S.C. .sctn. 119 of U.S.
Application No. 61/577209 filed 19 Dec. 2011 entitled COUNTER-FLOW
ENERGY RECOVERY VENTILATOR (ERV) CORE. PCT International
Application No. PCT/CA2012/050918 also claims priority from PCT
International Application No. PCT/CA2012/000560 filed 7 Jun. 2012
entitled SELECTIVE WATER VAPOUR TRANSPORT MEMBRANES COMPRISING A
NANOFIBROUS LAYER AND METHODS FOR MAKING THE SAME. All of these
applications are hereby incorporated herein by reference for all
purposes.
FIELD OF THE INVENTION
[0002] The present invention relates to heat and humidity
exchangers. Example embodiments provide energy recovery ventilator
(ERV) cores comprising a water-permeable membranes and ERV systems
that include such cores. The invention may be applied in any of a
wide variety of applications where heat and humidity exchange is
required. Examples include heat and moisture recovery in building
ventilation systems, humidification and heat transfer in fuel
cells, separation of gases, and desalination treatment of
water.
BACKGROUND
[0003] Heat and humidity exchangers (also sometimes referred to as
humidifiers) have been developed for a variety of applications,
including building ventilation (HVAC), medical and respiratory
applications, gas drying, and more recently for the humidification
of fuel cell reactants for electrical power generation. Many such
devices involve the use of a water-permeable membrane across which
heat and moisture may be transferred between fluid streams flowing
on opposite sides of the membrane.
[0004] Planar plate-type heat and humidity exchangers use membrane
plates that are constructed of planar, water-permeable membranes
(for example, Nafion.RTM., cellulose, polymers or other synthetic
membranes) supported with a spacer and/or frame. The plates are
typically stacked, sealed and configured to accommodate intake and
exhaust streams flowing in either cross-flow or counter-flow
configurations between alternate plate pairs, so that heat and
humidity are transferred between the streams via the membrane.
[0005] Other types of exchangers include hollow tube humidifiers
and enthalpy wheel humidifiers. Hollow tube humidifiers have the
disadvantage of high pressure drop, and enthalpy wheels tend to be
unreliable because they have moving parts and tend to have a higher
leak rate.
[0006] A heat recovery ventilator (HRV) is a mechanical device that
incorporates a heat and humidity exchanger in a ventilation system
for providing controlled ventilation into a building. The heat and
humidity exchanger heats or cools incoming fresh air using exhaust
air. Devices that also exchange moisture between the incoming fresh
air and the exhaust air are generally referred to as Energy
Recovery Ventilators (ERVs), sometimes also referred to as Enthalpy
Recovery Ventilators. An ERV may remove excess humidity from the
ventilating air that is being brought into a building or it may add
humidity to the ventilating air. ERVs may be used to save energy
and/or to improve indoor air quality in buildings.
[0007] ERVs typically comprise an enclosure, fans to move the air
streams, ducting, as well as filters, control electronics and other
components. The key component in the ERV which transfers the heat
and humidity between the air streams is called the core or the
exchanger. The two most common types of ERVs are those based on
planar membrane plate-type devices and those based on rotating
enthalpy wheel devices, both mentioned above. Planar plate-type ERV
cores use layers of static plates that are sealed and configured to
accommodate the intake and exhaust streams flowing in either
cross-flow or counter-flow configurations between alternate pairs
of plates.
[0008] FIG. 1 shows an example of a planar plate-type heat and
humidity exchanger made from stacked planar sheets of membrane 3
with rigid corrugated spacers 6 inserted between the membrane
sheets. The spacers maintain proper sheet spacing as well as
defining airflow channels 5 for wet and dry streams on opposite
sides of each membrane sheet, in a cross-flow arrangement, as
indicated by broad arrows 1 and 2 respectively. The stack is
encased within a rigid frame 4.
[0009] A benefit of planar plate-type heat and humidity exchanger
designs for ERV, fuel cell, and other applications, is that they
are readily scalable because the quantity (as well as the
dimensions) of the modular membrane plates can be adjusted for
different end-use applications. Existing planar plate-type ERV
cores are bulky and less effective than would be desired in
facilitating enthalpy exchange.
[0010] Another approach to heat and humidity exchanger design is to
incorporate a pleated water-permeable material in the exchanger.
For example, U.S. Pat. No. 4,040,804 describes a heat and moisture
exchanger for exchanging heat and moisture between incoming and
outgoing air for room ventilation. The exchanger has a cartridge
containing a single pleated sheet of water-permeable paper. Air is
directed in one direction along the pleats on one side of the
pleated paper, and the return air flows in the opposite direction
along the pleats on the other side of the pleated paper. The ends
of the cartridge are closed by dipping them in wax or a potting
compound that can be cast and that adheres to the paper. The pleats
are separated or spaced, and air passages between the folds are
provided, by adhering grains of sand to the pleated paper.
[0011] FIG. 2 shows an example of a heat and humidity exchanger
suitable for energy recovery ventilator (ERV) applications which
comprises a pleated water-permeable membrane cartridge disposed in
a housing. A plastic flow field element can be disposed within some
or all of the folds of the pleated membrane for directing the
stream over the inner surfaces of the folds, as described in US
Patent Application Publication No. 2008/0085437. The flow field
element controls the relative flow paths of the two streams on
opposite sides of the membrane and enhances flow distribution
across one or both membrane surfaces. The flow field elements can
also assist in supporting the pleated membrane and controlling the
pleat spacing within the pleated membrane cartridge. In the
embodiment shown in FIG. 2, a first fluid stream is directed in a
U-shaped flow path 122 from an inlet port 124 on one face of
housing 115 to an outlet port 128 on the same face of housing 115.
The first fluid stream is thus directed from inlet port 124 into a
set of substantially parallel folds 126 on one side of pleated
membrane cartridge 120, then along the length of the folds 126, and
then out via port 128. A second fluid stream is similarly directed
in a substantially U-shaped flow path 132 from an inlet port 134 to
an outlet port 138 on the same face of housing 115 (both ports 134
and 138 being on the opposite face of housing 115 from ports 124
and 128). The second fluid stream is directed from port 134 into a
corresponding set of substantially parallel folds 136 on the other
side of pleated membrane cartridge 120, then along the length of
the folds 136, and then out via port 138. The flow path 122 of the
first fluid stream is in a substantially counter-flow configuration
relative to flow path 132 of the second fluid stream.
[0012] There are also examples of ERV cores with stacked planar
membrane sheets that operate in a substantially counter-flow
configuration to transfer heat and humidity across planar membrane
sheets. The membrane sheets can be interleaved with rigid plastic
spacers that define flow channels as described in U.S. Pat. No.
7,331,376.
[0013] The flow field inserts or spacers used in the heat and
humidity exchangers described above often provide controlled or
directional gas flow distribution over the membrane surface.
However, the fluid flow paths across the membrane surface tend to
be quite tortuous and turbulent, so the flow can be quite
restricted and the pressure drop across the overall apparatus can
be significant. If there are many closely-spaced ribs to support
the membrane, the ribs will tend to impede or block the fluid flow,
and also increase pressure drop. With more widely-spaced ribs the
membrane can deflect into the channel also increasing the pressure
drop. Therefore, the use of non-permeable flow field inserts is
generally undesirable.
[0014] Compact heat and humidity exchangers or HRV cores in which
there is heat transfer between channels in two dimensions in
counter-flow are described in U.S. Pat. No. 5,725,051 in which the
heat transfer medium is a thermoformed rigid plastic sheet. The
plastic is impermeable to water so there is no humidity transfer
across the medium. In another similar example, the heat transfer
medium is aluminum, but again there is no humidity transfer because
the medium is not water-permeable.
[0015] As described above, conventional ERV cores with a
water-permeable membrane require a spacer to support the membrane.
Spacers generally impede or block heat and moisture transfer and
they can increase the pressure drop if there is deflection of the
membrane into the channel.
[0016] The inventors have recognized that there remains a need for
cost effective and efficient ERV systems and cores.
SUMMARY
[0017] This invention has several aspects and encompasses a wide
range of specific embodiments. Aspects of the invention provide
building ventilation systems; heat and humidity exchangers; cores
for heat and humidity exchangers; sub-assemblies for cores of heat
and humidity exchangers; and methods for fabricating heat and
humidity exchangers.
[0018] One example aspect provides a heat and humidity exchanger
comprising a core. The core comprises a plurality of water
vapor-permeable sheets. The sheets are layered or stacked. at least
some of the sheets are pleated to provide a plurality of groups of
channels extending through the core. Each of the plurality of
groups of channels comprises channels defined between two adjacent
ones of the sheets and extending along the pleats of at least one
of the pleated sheets. A plurality of plenums is formed on opposed
sides of the core. The plenums on each of the opposed sides of the
core are configured such that the channels of groups of channels on
opposing sides of the same one of the sheets are fluidly connected
to different ones of the plenums. The plenums are defined at least
in part by manifold members attached along opposite edges of the
sheets, at least one of the manifold members comprising a sheet
that is connected to and follows an edge of one of the pleated
water vapor-permeable sheets.
[0019] Another aspect provides a heat and humidity exchanger
comprising a core comprising a plurality of channels. A first group
of the plurality of channels extends from a first plenum through
the core to a second plenum. A second group of the plurality of
channels extends from a third plenum through the core to a fourth
plenum. Each of the plurality of channels in the first group has
walls in common with a plurality of the channels of the second
group and each of the plurality of channels in the second group
having walls in common with a plurality of the channels of the
first group. The plurality of channels is defined by a plurality of
water vapor-permeable membrane sheets. At least one of the water
vapor-permeable membrane sheets being pleated. The pleated water
vapor-permeable membrane sheet defines a plurality of the walls of
each of a plurality of the first group of channels. The first and
fourth plenums are separated at least in part by a manifold sheet
that is connected to and follows an edge of the pleated water
vapor-permeable membrane sheet.
[0020] Another aspect provides a heat and humidity exchanger
comprising a core comprising a plurality of channels each having a
triangular cross-section. A first group of the plurality of
channels extends from a first plenum through the core to a second
plenum. A second group of the plurality of channels extends from a
third plenum through the core to a fourth plenum. Each of the
plurality of channels in the first group has walls in common with a
plurality of the channels of the second group and each of the
plurality of channels in the second group has walls in common with
a plurality of the channels of the first group. Each of the common
walls is water vapor-permeable.
[0021] Another aspect provides a heat and water vapor exchanger
comprising a core structure comprising a plurality of layered water
vapor permeable sheets attached together to form a self-supporting
structure. A plurality of the layered water vapor permeable sheets
are pleated such that triangular channels extend through the core.
A manifold structure comprises manifold members attached along
edges of the vapor permeable membrane sheets of the core. The
manifold members form stacked plenums such that channels extending
through the core between different pairs of adjacent ones of the
water vapor permeable membrane sheets are in fluid communication
with different ones of the plenums.
[0022] Further aspects of the invention and features of example
embodiments of the invention are described below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] The accompanying drawings illustrate non-limiting
embodiments of the invention.
[0024] FIG. 1 is an isometric view of a heat and humidity exchanger
comprising a stack of planar membrane layers interleaved with rigid
corrugated spacers (prior art).
[0025] FIG. 2 is an isometric view of a heat and humidity exchanger
comprising a pleated membrane cartridge disposed in a housing
(prior art).
[0026] FIG. 3 is a schematic cross-sectional view of a pleated
water-permeable membrane.
[0027] FIG. 4A is a schematic cross-sectional view illustrating two
pleated water-permeable membrane sheets that can be joined to form
a diamond-shaped channel. FIG. 4B is a schematic cross-sectional
view illustrating four pleated water-permeable membrane sheets
arranged to form an array of diamond-shaped channels. FIG. 4C is a
schematic cross-sectional view of a pleated membrane combination
like those shown in FIGS. 4A and 4B with flattened peaks. FIG. 4D
is a non-isometric 3D view of an embodiment of an ERV core showing
the central pleated membrane section with diamond- or
parallelogram-shaped channels.
[0028] FIG. 5A is a schematic cross-sectional view illustrating two
box-pleated water-permeable membrane sheets that can be joined to
form channels of a square or rectangular cross-section. FIG. 5B is
a schematic cross-sectional view illustrating four pleated
water-permeable membrane sheets arranged to form an array of
square- or rectangular-shaped channels.
[0029] FIG. 6A is a schematic cross-sectional view illustrating a
pleated and a flat sheet of water-permeable membrane that can be
joined to form channels of triangular cross-section. FIG. 6B is a
schematic cross-sectional view showing a stack of alternating
pleated and flat sheets of water-permeable membrane forming a
sub-assembly of channels of triangular cross-section.
[0030] FIG. 7A is a simplified exploded 3D view of a pair of
pleated membranes forming parallel channels with a diamond-shaped
cross-section, with manifold sections attached to each membrane
sheet. FIG. 7B shows a simplified 3D partial cut-away view of the
assembly of FIG. 7A with two fluid streams following through the
diamond-shaped channels in counter-flow.
[0031] FIG. 8 is a plan view of the upper manifold/membrane
assembly shown in FIGS. 7A & 7B.
[0032] FIG. 9A is a cross-sectional view at location A-A in FIG. 8.
FIG. 9B shows a view looking down the channels from a cross-section
at location B-B in FIG. 8. FIG. 9C shows a view looking down the
channels from a cross-section at location C-C in FIG. 8. FIG. 9D is
a cross-sectional view at location D-D in FIG. 8 showing the
zig-zag cross-section of the pleated membrane.
[0033] FIG. 10 is a diagram showing how the plenums created between
adjacent manifold sections in a stacked core assembly (similar to
that shown in FIG. 7) correspond to the diamond-shaped channels
that they are supplying/discharging.
[0034] FIG. 11A is a simplified exploded isometric view of an
assembly like that of FIG. 7A, but interleaved with an additional
flat membrane sheet forming parallel channels with a
triangular-shaped cross-section. FIG. 11B shows the flow of the two
fluid streams on opposite sides of a manifold section that has ribs
to direct the flow. FIG. 11C is a plan view illustrating the flow
pattern of the two fluid streams in an assembly similar to the one
shown in FIG. 11A.
[0035] FIG. 12 is a diagram showing how the plenums created between
the flat membrane sheets and adjacent manifold sections in a
stacked core assembly (similar to that shown in FIG. 11) correspond
to the triangular-shaped channels that they are
supplying/discharging.
[0036] FIG. 13 shows how the plenums created between adjacent
manifold sections in a stacked core assembly similar to that shown
in FIG. 5B would correspond to the square-shaped channels that they
are supplying/discharging.
[0037] FIG. 14A is a plan view of a manifold/membrane subassembly
with a central pleated membrane and a manifold section at each end,
where the channels have a diamond cross-section. FIG. 14B is a plan
view of a manifold/membrane subassembly with a central pleated
membrane and a manifold section at each end, where the channels
have a triangular cross-section.
[0038] FIG. 15 is a photo of a compression molded layer made
entirely from a formable water permeable membrane.
[0039] FIG. 16 is a graph illustrating the performance of an ERV
core comprising a prototype stacked pleated membrane core.
[0040] FIG. 17 is a graph illustrating the pressure drop for two
prototype ERV cores comprising stacked triangular-pleated
membranes.
[0041] FIG. 18 is a graph illustrating the performance of the two
prototype ERV cores comprising stacked triangular-pleated
membranes.
DETAILED DESCRIPTION
[0042] FIGS. 1 and 2 are described above.
[0043] Performance of heat and humidity exchangers can be improved,
and the required heat and humidity exchanger size can be reduced,
by providing heat and humidity exchanger constructions that provide
one or more of: enhancing flow distribution across one or both
surfaces of heat and vapor exchange membranes; controlling the
relative flow paths of fluids on opposite sides of heat and vapor
exchange membranes; providing improved support for heat and vapor
exchange membranes; reduced pressure drop across the heat and
humidity exchanger; increased membrane surface area per unit volume
of the exchanger; and/or membranes that have improved water
transport and other properties.
[0044] Certain embodiments disclosed herein provide ERV cores with
water-permeable membranes configured to allow multi-dimensional
transfer of moisture as well as heat. Multi-dimensional transfer
across a water-permeable membrane can provide more efficient energy
recovery and allow the ERV core to be more compact for a given
level of performance. Embodiments as described herein may be used
to transfer heat and moisture between two streams flowing in a
counter-flow configuration for more efficient energy recovery.
[0045] Designs and manufacturing methods as described herein may be
applied to provide ERV core constructions that are free of spacers.
In such constructions, thin, flexible membranes may be shaped and
attached to one another to provide self-supporting layers and core
structures that are robust enough to withstand significant pressure
differentials.
[0046] FIG. 3 is a cross-sectional view showing a sheet of pleated
water-permeable membrane. The pleated membrane defines the walls of
channels through which a fluid stream (e.g. wet or dry air) can be
directed to flow, and across which heat and humidity may be
exchanged. The membrane may be attached to plastic manifold
sections (as described in more detail below) to direct the fluid
stream from inlet ports into the channels and from the channels to
outlet ports. The membrane should be sufficiently thin to allow
adequate exchange of heat between the two streams, driven by the
temperature gradient between the streams. The membrane is also
water-permeable to allow moisture to pass through the material,
driven by the vapor pressure differential or water concentration
gradient between the two streams. Thinner membranes will tend to
have higher heat and moisture transport rates. Ideally the membrane
is also impermeable to air, and contaminant gases, to prevent the
mixing and crossover of the two streams through the membrane.
[0047] In the present approach, layers of pleated membrane are
stacked to form a sub-assembly or cartridge for disposition in a
heat and humidity exchanger. The pleated membrane may be prepared,
for example, by folding a sheet of membrane such as with heat
and/pressure to provide plastic deformation to the folded edge
(e.g. with push-bar pleating technology), or by forming a membrane
to have pleats, such as with gears or score-and-pleat rotary
pleating technology. The angle of the pleats may be varied. For a
constant channel hydraulic diameter, larger pleat tip angles allow
more layers of membrane to be provided in a core of a certain
height, but with less overall membrane area per layer. Conversely,
for a constant channel hydraulic diameter, smaller pleat tip angles
will provide more membrane area per layer but fewer layers for the
same core. In some embodiments, the pleats are formed to have
angles in the range of 70 degrees to 100 degrees. Some embodiments
have pleat angles in the range of 50 to 70 degrees (e.g. 60
degrees). Pleat tip angles close to 60 degrees can advantageously
provide improved heat and mass transfer, with the high use of
membrane area, for a given core height.
[0048] FIG. 4A is a cross-sectional view illustrating two pleated
water-permeable membrane sheets that can be joined to form channels
with a diamond-shaped cross-section (or a parallelogram-shaped
cross-section). The peaks of one pleated membrane can be attached
to the peaks of the adjacent pleated membrane, for example, by
gluing, bonding, heat-welding or sealing. In this configuration,
the joined pleated membrane sheets are self-supporting and require
no spacer or supporting material other than the membrane itself.
Adhering, or otherwise attaching, peaks in one pleated membrane
sheet to peaks in adjacent membrane sheets can provide sufficient
strength for the membrane channel to withstand a pressure
differential. In some embodiments, a polyurethane glue is used to
adhere the peaks of one pleated membrane to the corresponding peaks
of an adjacent membrane. Other suitable glues or adhesives can also
be used for the same purpose. Glues that are permeable to water
vapor will allow water transport to occur even in the regions where
the pleated membranes are attached to one another. Glues that are
permeable to water vapor transfer may be of the class that are
polymer-based, with soft chain sections that allow water to pass
through, such as Permax.TM. from Lubrizol. Depending on the
membrane material, it may be possible to weld the pleated membrane
sheets to one another at the peaks. For example, thermal, vibration
or ultrasonic welding may be used.
[0049] FIG. 4B is a cross-sectional view illustrating four pleated
water-permeable membrane sheets arranged to form an array of
diamond-shaped channels. Two different fluid streams can be
directed through alternate channels in a counter-flow
configuration. Flow into the plane of the paper is indicated by a
cross, and flow out of the plane of the paper is indicated by a
dot. In such an array each diamond-shaped channel shares its walls
with as many as four other channels. Heat and humidity can be
transferred across all four walls of the channel through the
water-permeable membrane. For a given channel, the flow in adjacent
channels is in the opposite direction to the flow in the given
channel. This is referred to as a counter-flow configuration.
[0050] Each fluid stream is independent of the other and does not
depend on the peak-to-peak adhesion of the pleated membranes to
provide a seal, so there is reduced potential for cross-leakage
between the two streams. If a peak seal were not perfect, any leak
into an adjacent channel would be a channel carrying the same
fluid, and would not cause mixing of the two streams or adversely
affect heat or mass transfer.
[0051] FIG. 4C is a cross-sectional view also showing an
arrangement of water-permeable membrane sheets forming an array of
diamond-shaped channels. In this example, the peaks of the
diamonds, along the pleated lines of the membrane, are flattened to
provide a larger area for attachment to peaks in adjacent membrane
sheets. This embodiment can provide a mechanically stronger
sub-assembly of membrane sheets with substantially the same
sensible and latent transfer as the arrangement shown in FIG. 4B.
An alternative to flattening the peaks is to form the peaks of one
pleated membrane layer, with a small trough or valley that extends
along the crests of the peaks. Peaks of an adjacent layer may then
nest into the troughs or valleys. Such troughs or valleys may be
formed in the crests on only one face of the pleated membrane layer
or in the crests on both faces of the pleated membrane layer.
[0052] FIG. 4D shows a 3D representation of a stacked pleated
membrane sub-assembly with diamond-shaped channels. Even though it
can be made using a thin, flexible membrane material, the structure
is self-supporting. This approach of stacking and gluing (or
otherwise attaching) pleated membrane sheets provides a very high
membrane surface area per unit volume of the exchanger providing a
device with high effectiveness of heat and moisture transfer.
[0053] FIG. 5A is a cross-sectional view illustrating two
box-pleated water-permeable membrane sheets that can be joined to
form channels with a square or rectangular cross-section. In this
example, the box-pleats form a castellation, and the castellation
pattern is offset between adjacent membrane sheets allowing the
sheets to be joined to form square or rectangular channels. Each
pleat line on one of the membrane sheets is glued, or otherwise
attached, to the corresponding pleat line on an adjacent membrane
sheet. Like the diamond configuration described above, the glued
membrane sheets are self-supporting and require no spacers or other
material to provide rigidity or support, and the channels are able
to withstand pressure differentials.
[0054] FIG. 5B is a cross-sectional view illustrating four
box-pleated water-permeable membrane sheets arranged to form an
array of square-shaped or rectangular-shaped channels. Two
different fluid streams can be directed through alternate channels
in a counter-flow configuration. As before, flow into the plane of
the paper is indicated by a cross, and flow out of the plane of the
paper is indicated by a dot. Each channel shares its walls with as
many as four other channels. Heat and humidity can be transferred
across all four walls through the water-permeable membrane.
[0055] The square- and diamond-shaped channels arrangements are
topologically and functionally equivalent, and sub-assemblies with
square channels can be oriented during assembly to provide diamond
channels and vice versa. Other channel shapes such as
parallelograms may also be created by stacking layers of pleated
membranes.
[0056] In some embodiments, the pleated membrane sheets may be
separated by a mesh or other suitable material, configured in a
sheet or in strips arranged perpendicular to the channels, or other
suitable configuration. This construction can be used instead of,
or in addition to, the use of glue or welding along the pleat
lines. This approach can reduce the tendency for the pleats to slip
into one another during assembly and can provide structural
support. This construction can be applied in the square or diamond
arrangements described above.
[0057] FIG. 6A is a cross-sectional view showing a pleated
water-permeable membrane sheet and a flat water-permeable membrane
sheet positioned below it. The pleated lines (the lower peaks in
the cross-sectional view) in the pleated membrane sheet can be
glued, welded or otherwise attached to the flat membrane sheet to
create parallel channels of triangular cross-section. These
channels each have three boundaries across which heat and humidity
can be transferred. Stacking alternate sheets of pleated membrane
and flat membrane creates a mechanically self-supported structure
that requires no spacers or other supporting material. In this
arrangement, again all flow channels walls are water-permeable
allowing heat and humidity transfer to occur between all adjacent
channels.
[0058] FIG. 6B is a cross-sectional view of a stack of membrane
sheets in this configuration with the membranes forming an array of
channels that are triangular in cross-section. Two different fluid
streams can be directed through alternate channels in a
counter-flow configuration. As before, flow into the plane of the
paper is indicated by a cross, and flow out of the plane of the
paper is indicated by a dot. Each channel shares its walls with as
many as three other channels. Heat and humidity can be transferred
across all three walls through the water-permeable membrane.
[0059] The manufacturing method of pleating and then gluing,
welding or otherwise attaching pleated membrane sheets to one
another allows thinner membrane materials to be used and still have
the strength to be self-supporting in the resulting 3D-structure.
The resulting sub-assembly does not have to be held under tension.
Furthermore this self-supporting structure can provide channels
having walls that offer increased rigidity because they are
supported by other parts of the structure even though the walls may
be formed of a relatively thin, flexible membrane material. This
increased rigidity may offer reduced pressure drop and improved
uniformity of flow distribution through the core. Further, the
structure facilitates providing channels that have consistent
channel dimensions which further aids in achieving good uniformity
of flow among the channels.
[0060] In the embodiments of stacked, pleated membrane
sub-assemblies described above the pleated water-permeable membrane
layers define a three-dimensional array of parallel channels
arranged in a regular pattern. Each of the channel walls, defined
by the membrane material, separates channels of first and second
types, e.g. for carrying wet and dry streams, respectively. The two
fluid streams can be directed through the channels so that the wet
and dry streams flow in counter-flow to one another. This provides
more efficient transfer of heat and moisture with high sensible and
latent transfer.
[0061] In order to provide manifolds for supply and discharge of
the gas streams, the individual sheets of pleated membrane can each
be attached to a manifold section (before they are stacked) forming
a manifold/membrane sub-assembly. The manifold/membrane
sub-assemblies may then be stacked and glued together to form a
core. The manifold section can be in the form of a unitary frame
that borders the sheet of pleated membrane on all sides, or can be
in two (or more) separate pieces that are, for example, attached to
opposite ends of the pleated membrane sheet.
[0062] The manifold section can be made of a different material
than the membrane, such as a material that is not permeable to
water or gas, and is stiffer and stronger than the membrane. For
example, the manifold section material can be plastic, aluminum or
any other suitable material that provides some structural support
to the membrane and the stacked core, while still providing heat
transfer in the manifold region. Preferably the material of the
manifold section is less than 0.012 inches (about 1/4 mm) in
thickness. The manifold section may be made of a flame retardant
material which will reduce the tendency for a flame to spread to
the membrane section and increase compliance with flammability
requirements. For example, the manifold section may be made of
aluminum or other metals; PVC, which is generally inherently
self-extinguishing; or a plastic comprising one or more
flame-retardant additives, such as magnesium hydroxide.
[0063] Manifold sections may be made in a wide range of different
ways. For example, features in manifold section(s) can be
vacuum-formed or thermoformed or stamped therein. In some
embodiments the manifold sections are formed with features and then
attached to the membrane. Alternatively the manifold sections could
be injection molded as separate plastic pieces, and then attached
to the pleated membrane, or they could be injection molded directly
onto the edges of the pleated membrane. The membrane can be adhered
to the manifold section using a suitable glue, adhesive or other
bonding agent, tape or the like. Some polyurethane-based glues have
been found to be suitable for this purpose. Other types of adhesive
can be used, such as epoxies, hot melts, cyanoacrylates, and even
membrane coating materials that may also be useful to prevent or
reduce cross-over contamination. Alternatively, depending on the
membrane and manifold section material, it may be possible to
thermally weld, vibration weld, ultrasonically weld, or otherwise
bond the components together.
[0064] The attachment of the membrane to the manifold section
should create a leak-proof seal to prevent cross-contamination
between the two fluid streams. The bond should be strong enough to
prevent delamination of the membrane from the manifold section when
there is a high differential pressure between the fluid streams on
opposite sides of the membrane.
[0065] A benefit to this composite structure with pleated membrane
adhered to the transitioning manifold sections is that the manifold
sections may provide mechanical support to the water transfer
membrane. Where manifold sections provide such mechanical support,
the core may be self-supporting with reduced attachment between
adjacent layers. Each layer may be constructed separately. The
layers may each form a self-supporting structure, much like a
truss. The layers, each including manifold sections and a
moisture-exchange section may then be stacked together to form a
heat and humidity exchanger.
[0066] The ratio of water-permeable membrane area to water
impermeable manifold material area in the layers of the pleated
membrane core assembly may be adjusted to adjust the relative
amounts of sensible heat and latent heat (moisture) that are
transferred by the pleated membrane core. Increasing the area of
water permeable membrane facilitates increased moisture
transfer.
[0067] In other embodiments the manifold section may comprise the
same material as the water permeable membrane region, for example
the manifold section may comprise a water-permeable membrane layer
that is formable. This sheet of formable material may make up a
layer that includes both a pleated region which will define
counter-flow channels when stacked together with an adjacent layer
and manifold regions that are configured so as, when stacked
together with an adjacent layer, to direct a flow into channels at
one end of the pleated region and to receive the flow on the other
side of the pleated region (see FIG. 15 below, for example). For
example, such a layer may be made of coated PET non-woven membrane,
with properties that allow it to be molded or formed with pleats,
ribs, bumps, and/or other out-of-plane features through the
application of heat and/or pressure. Embodiments where a manifold
section is also water-permeable permit increased humidity transfer
due to the larger transfer area. The transition from the inlet or
outlet to the center straight channels can follow the same lofting
as described below, to transition from a wide rectangular area into
alternating cells of channels arranged laterally.
[0068] The design of the manifold sections is such that, when they
are stacked in the assembled core, they enable a first fluid stream
to enter into alternate channels laterally (a first type of
channel), and enable a second fluid stream (flowing through the
core in the opposite direction) to exit from the other channels
(second type of channel). Similarly at the other face of the core,
the manifold receives the first fluid stream from the first channel
type and directs the second fluid stream into the alternating
channels of the second type. The two fluid streams are fluidly
isolated from one another so that they do not mix. The manifolds
can be designed to ensure smooth flow transition between the
manifold regions and the channels so as to reduce or minimize the
overall pressure drop through the exchanger device.
[0069] The manifold sections may be constructed to include features
that improve performance of a heat and humidity exchanger by
providing increased heat and/or humidity transfer between fluids
and/or reduced pressure drop. For example: [0070] a. Ribs in intake
manifold sections may be configured to direct flow evenly into each
channel, and ribs in output manifold sections may be configured to
allow flow from multiple channels to smoothly recombine into an
output flow; [0071] b. In embodiments where the manifold is bounded
on one side by a flat membrane sheet, ribs in the manifold sections
may be arranged to provide good support to the membrane sheet by
providing closer rib-to-rib spacing especially in areas where the
membrane sheet could sag; [0072] c. Material of the manifold
sections may be made thin (e.g. 0.004 inches to 0.012 inches--about
0.01 cm to 0.03 cm). The use of thin materials for the manifold
section can enhance the smoothness of the transitions from channels
into the manifolds, increase the cross-sectional areas of plenums
formed between the manifold sections, and also improve heat
transfer through the material of the manifold sections.
[0073] FIG. 7A shows a simplified exploded 3D view of an assembly
700 comprising a pair of pleated membrane sheets 710 and 720 that,
when stacked, form parallel channels with a diamond-shaped
cross-section. Manifold sections 730 and 740 are attached to each
membrane sheet. The two manifold sections form a plenum 750 between
them, with a rectangular opening via which a first fluid stream can
be supplied to the channels formed between the two membrane layers.
The stacked manifold sections 730 and 740 are shaped to provide
smooth transition regions 735 and 745 between the plenum 750, which
has a rectangular cross-section, and the triangles that form half
of each diamond-shaped channel. As another assembly is stacked
above the one illustrated in FIG. 7A, a similar plenum is formed
above the upper manifold section 730, for the second fluid steam
which is exiting the diamond-shaped channels defined in part by
upper surface of the upper membrane 710. Thus the stacked manifold
sections form a series of layered plenums alternating for the first
and second fluids respectively. FIG. 7B shows a simplified 3D
partial cut-away view of two fluid streams following through the
diamond-shaped channels in counter-flow. The first fluid stream
(indicated by arrows 770) enters a first set of diamond-shaped
channels 775 via the plenum formed between the two manifold
sections 730 and 740, and the second fluid stream (indicated by
arrows 780) exits a second set of diamond-shaped channels 785 via
the plenum formed above the upper manifold section 730. The fluids
are in a cross-flow configuration in the manifold region.
[0074] FIG. 8 is a plan view of the upper manifold/membrane
assembly shown in FIGS. 7A & 7B.
[0075] FIGS. 9A-D are intended to illustrate the smooth transition
from the manifold region into the channels. FIG. 9A is a
cross-sectional view at location A-A in FIG. 8. FIG. 9A shows the
plenum 750 for the first fluid stream 770 below the manifold
section 730, and the plenum for the second fluid steam 780 above
the manifold section 730. The first stream 770 enters the lower
plenum 750 and the second stream 780 exits the upper plenum, as
indicated by the broad arrows. FIG. 9B shows a view looking down
the channels from a cross-section at location B-B in FIG. 8. The
plenum floor/roof is still flat at this point but gradually
transitions into a zig-zag cross-section to correspond to the
membrane pleats. These transitions in the transition region 735 of
manifold section 730 are visible in FIG. 9B as solid triangles
above and below the flat plane of the plenum roof/floor. FIG. 9C
shows a view looking down the channels from a cross-section at
location C-C in FIG. 8. This shows the gradual shaping of the
manifold section in transition region 735 into a wavy
cross-section. At this point the waves are not quite as deep as the
zig-zag membrane pleats, and the further slope of manifold
transition regions 735 are visible above and below the wavy
cross-section in FIG. 9C. FIG. 9D is a cross-sectional view at
location D-D in FIG. 8 showing the zig-zag cross-section of the
pleated membrane 710.
[0076] FIG. 10 shows how the plenums created between adjacent
manifold sections in a stacked core assembly (similar to that shown
in FIG. 7A) correspond to the diamond-shaped channels that they are
supplying/discharging. The first fluid can flow in a straight path
between the unshaded area of the channels of the first type and the
supply plenum for the first fluid. Similarly, the second fluid can
flow in a straight path between the unshaded area of the channels
of the second and the discharge plenum for the second fluid. In
this embodiment there is a straight path connection between the
plenum and most of the cross-sectional area of the corresponding
channels. This reduces the pressure drop by avoiding an abrupt
transition in the direction of flow, and eliminating the need for a
long transition region, between the plenum and the channel.
[0077] FIG. 11A shows a simplified exploded isometric view of an
assembly 1100 like that of FIG. 7A, but with an additional flat
membrane sheet 1115 interposed between the pair of pleated membrane
sheets 1110 and 1120 thereby forming parallel channels with a
triangular-shaped cross-section. The pleated membranes 1110 and
1120 are preferably glued or otherwise bonded to the flat membrane
sheet 1115 along the pleat lines, to improve structural rigidity of
the assembly and to allow the membrane channels to better withstand
pressure differentials. The bond along the pleat lines does not
need to be leak-proof, however, as any leak would be into an
adjacent channel of the same type (i.e. carrying the same fluid
stream). Manifold sections 1130 and 1140 are attached to each
pleated membrane sheet. Plenums 1150 and 1155, each with a
rectangular opening, are formed between each manifold section 1130
and 1140 and the adjacent flat membrane sheet 1115, via which a
first and second fluid streams can be supplied to the channels
formed between the pleated and flat membrane layers. The manifold
sections 1130 and 1140 are shaped to provide smooth transition
regions 1135 and 1145 between the plenums, which have a rectangular
cross-section, and the triangular-shaped channels. FIG. 11B shows
the flow of two fluid streams (in a cross-flow configuration) on
opposite sides of one manifold section 1130a that in the
illustrated embodiment has ribs 1190 to direct the flow and support
the membrane 1115. FIG. 11C is a plan view illustrating the flow
pattern of two fluid streams in an assembly similar to the one
shown in FIG. 11A.
[0078] In the embodiment illustrated in FIG. 11A, the flat membrane
sheet extends into manifold region. This can be advantageous as it
allows heat and moisture transfer to occur between the fluid steams
in adjacent plenums, as well as in the pleated membrane region.
However, without adequate support in this region, deflection of the
membrane can occur, increasing the pressure drop, and so it may be
necessary to provide supporting ribs or features in the manifold
sections. The flat sheet of membrane is attached to the edges of
the adjacent manifold sections to create a leak-proof seal.
Suitable adhesives, or welding techniques may be used, such as for
example, thermal welding, vibration welding, ultrasonic welding, or
RF welding.
[0079] In other similar embodiments, the flat membrane sheet does
not extend into the manifold region, but is attached to manifold
sections made from a different material. These stack with the
manifold sections shown in FIG. 11A to define alternating plenums
for the first and second fluid streams. In either case, the stacked
manifold sections are shaped to provide smooth transitions between
the plenums (which have a rectangular cross-section) and the
triangular-shaped channels.
[0080] FIG. 12 shows how the plenums created between the flat
membrane sheets and adjacent manifold sections in a stacked core
assembly (similar to that shown in FIG. 11A) correspond to the
triangular-shaped channels that they are supplying/discharging. The
first fluid can flow in a straight path between unshaded area of
the channels of the first type and the supply plenum for the first
fluid. Similarly, the second fluid can flow in a straight path
between the unshaded area of the channels of the second type and
the discharge plenum for the second fluid. Once again, in this
embodiment there is a straight path connection between the plenum
and most of the cross-sectional area of the corresponding
channels.
[0081] A manifolding arrangement similar to those described above
can be provided for box-pleated membrane sub-assemblies, such as
shown in FIG. 5B. FIG. 13 shows how the plenums created between
adjacent manifold sections in such a stacked core assembly would
correspond to the square-shaped channels that they are
supplying/discharging. The first fluid can flow in a straight path
between unshaded area of the channels of the first type and the
supply plenum for the first fluid. Similarly, the second fluid can
flow in a straight path between the unshaded area of the channels
of the second type and the discharge plenum for the second fluid.
In this embodiment there is a straight path connection between the
plenum and about 50% of the cross-sectional area of the
corresponding channels.
[0082] The manifold sections can have features formed in one or
both surfaces to direct the flow from the plenums into the
corresponding channels, such as the ribs shown in FIG. 11B. Such
features can, for example, improve flow distribution. They can also
support the membrane if it extends into this region (for example,
as in the embodiments illustrated in FIG. 11A). Features that will
promote mixing or turbulence of the fluid streams can also be
incorporated into the manifold sections to improve performance. The
use of vacuum-formed or thermoformed manifold entrance and exit
sections allows a variety of counter-flow sizes to be produced with
varying channel heights without significant investment in tooling
(such as would be the case with injection molded separators
currently in use).
[0083] In illustrated embodiments the manifold members are each
connected to the core along a first edge, have an up-turned wall
along a second edge and a down-turned wall along a third edge such
that, when stacked together the manifold members form a column of
plenums that open alternately to sides corresponding to the first
and second edges.
[0084] FIG. 14A is a plan view of a manifold/membrane subassembly
1400 with a central pleated membrane 1410 and manifold sections
1430 and 1440 attached at each end, where the channels have a
diamond cross-section. The manifold sections 1430 and 1440 include
ribs on one side to direct the fluid stream into the respective
channels. FIG. 14B is a plan view of a manifold/membrane
subassembly 1450 with a central pleated membrane 1460 and manifold
sections 1480 and 1490 attached at each end, where the channels
have a triangular cross-section. In this embodiment the manifold
sections 1480 and 1490 include ribs on both sides of the midplane
of the manifold section to direct the fluid streams into the
respective triangular-shaped channels.
[0085] The assembled core can be potted along the sides and ends.
It can be encased in a metal or plastic frame which can also assist
in blocking flame spread to allow for compliance with flammability
standards. A metal frame can also act as a heat sink. For ERV
applications the core can be housed in an enclosure, which can also
house fans to move the air streams, ducting, as well as filters,
control electronics and other components.
[0086] The present membrane cores are readily manufacturable and
can be readily scaled to different sizes, as the pleated membrane
can be cut to different sizes to suit the particular end-use
application and the number of layers in the stack can be
varied.
[0087] Any membrane material that can be pleated and has the
requisite water-permeability and other properties, is suitable for
use in the above-described pleated membrane cores. Membranes that
have been used or suggested for ERV applications include cellulose
films; cellulose fibre or glass fibre papers or porous polymer
films that are coated or impregnated with a hydrophilic polymer or
a hydrophilic polymer-desiccant mixture; thin film composites
manufactured via interfacial polymerization; laminated membranes
made from a blown film on a non-woven support layer; laminated
membranes comprising an ionomer film bonded to a porous support;
and sulphonated and carboxylated ionomer films. Other materials
involve applying a water-permeable coating to the microporous
substrate. Composite membrane materials comprising a porous
desiccant-loaded polymer substrate that is coated on one surface
with a water-permeable polymer have been found to be particularly
suitable for ERV and similar applications. Examples of such
membranes are described in published PCT Application No.
WO2010/132983. Membranes of this type can retain a pleat once
folded, which tends to increase the strength of the membrane
channels in the core designs described herein.
[0088] In some embodiments, a membrane that is formable or can be
corrugated may be used. Engineered composite membrane materials
which can be formed to create features and hold various structures,
may allow increased performance and decreased cost in
membrane-based devices such as those described herein. For example,
the use of a electrospun nanofibrous membrane on a formable backer
in a counter-flow heat and humidity transfer device takes advantage
of the formable property of the membrane. A number of methods may
be available with which to form the membrane, e.g. with channels or
other features, (with or without the use of heat) such as
compression molding, vacuum forming or stamping.
[0089] FIG. 15 is a photo of a layer made entirely from a formable
water permeable membrane comprising a coated nanofibrous layer on a
polyester spunbond nonwoven fabric support layer. The layer
comprises manifold regions at each end, and a central section with
straight channels, all made of the same material. The features were
formed in the membrane layer by heating it (80.degree. C.) in a
compression mold. Such layers can be stacked to form an ERV core
assembly In a specific example embodiment, sheets of polyester
spunbond nonwoven fabric (Smash Specialty Nonwoven Y15100) were
obtained from Asahi Kasei. These materials are designed for
formability under low heat (<100.degree. C.). Coatings of PAN
nanofibres were deposited on these support layers with three
different loadings. The nanofibrous layers were then impregnated
with aqueous solutions of a polyetherpolyurethane co-polymer at
three concentrations (13, 15, and 17% by weight). The materials
were dried in an oven at 50.degree. C.
EXPERIMENTAL EXAMPLES
Example 1
First Prototype ERV Core--Multi-Directional Transfer
[0090] Multi-directional transfer was demonstrated using a
prototype with a vacuum-formed corrugated plastic spacer designed
to have approximately the same heat transfer as a pleated membrane.
The prototype showed the predicted increase in heat transfer
compared to a counter-flow design with only vertical
(1-dimensional) transfer for the same pressure drop. The increase
was due to the multi-dimensional nature of the transfer.
Example 2
Second Prototype ERV Core--Pleated Membrane
[0091] A second prototype was made using pleated membrane in the
counter-flow section, with thermoformed plastic manifold sections
for the entrances and exits. A polyurethane glue was used to attach
the membrane to the manifold sections. When compared on a
normalized flow basis, the heat transfer compared favorably to
state-of-the-art commercial HRV cores. The prototype performed
better in moisture transfer than commercially available cores.
[0092] The graph shown in FIG. 16 shows the performance of an ERV
core, comprising this second prototype stacked pleated membrane, as
a function of flow rate. The graph shows the effectiveness of
sensible heat and latent (moisture) transfer for the pleated
membrane core.
Example 3
Third and Fourth Prototype ERV Cores
[0093] A third prototype was made with triangular channels in a
core with a larger footprint size. A fourth prototype was also
built with taller triangular channels.
[0094] Dimensions of the channels may be selected to provide a
desired balance between rate of heat and mass transfer and pressure
drop. The third prototype triangular-pleated membrane core had a
pitch, or layer-to-layer membrane spacing, of 3.2 mm in the
straight counter-flow section. This resulted in a channel entrance
height of approximately 1.6 mm. Such a small height signifies a
relatively low hydraulic diameter in the entrance and exit areas of
each layer, resulting in a pressure drop that was higher than
desired. The fourth prototype was constructed to demonstrate that
pressure drop can be reduced by providing different channel
dimensions. In the fourth prototype, the layer-to-layer spacing was
4.5 mm. This increased the entrance and exit heights of the
manifolds to approximately 2.2 mm. The reduction in pressure drop
achieved in the fourth prototype versus the third prototype is
illustrated in FIG. 17.
[0095] With an increase in pitch spacing in the center channel
section, fewer layers would be incorporated for the same overall
height, or volume, of core. A reduction in number of layers would
result in a reduction in the overall membrane surface area in the
core, reducing the transport area and diminishing performance.
However, this was compensated in the fourth prototype by
incorporating more tightly spaced pleats (less distance between
pleats) in the pleated counter flow sections, thereby packing more
membrane in the straight counter-flow section in the middle of the
core. By going from about a 90.degree. pleat tip angle to about a
60.degree. pleat tip angle, enough membrane was incorporated into
the fourth prototype to offset the reduction in the number of
layers.
[0096] An ERV is typically operated in laminar flow in the layers
of the core, so heat and mass transfer is only a function of
hydraulic diameter and Nusselt number (a type of dimensionless
temperature gradient), which is constant for a given geometry if
the flow is laminar. As discussed in the literature (e.g., Int. J.
Heat Mass Transfer, Vol. 18, pp. 849-862, 1975), for triangular
ducts in laminar flow the Nusselt number will decrease as one moves
away from an equilateral triangle. The change of pleat angle from
90.degree. to 60.degree. in the fourth prototype therefore also
compensated for the decrease in number of layers.
[0097] The graph shown in FIG. 18 shows the performance of these
third and fourth prototype ERV cores, as a function of flow rate.
The graph shows the effectiveness of sensible heat and latent
(moisture) transfer was quite similar for the two prototypes.
[0098] Heat and humidity exchangers as described herein may be
applied, for example, to exchange heat and humidity between a flow
of fresh air entering a building and a flow of air being vented
from a building.
[0099] While a number of exemplary aspects and embodiments have
been discussed above, those of skill in the art will recognize
certain modifications, permutations, additions and sub-combinations
thereof. It is therefore intended that the following appended
claims and claims hereafter introduced are interpreted to include
all such modifications, permutations, additions and
sub-combinations as are within their true spirit and scope.
[0100] Some non-limiting example enumerated embodiments of the
present invention are as follows: [0101] 1. A heat and humidity
exchanger comprising: [0102] a core comprising a plurality of water
vapor-permeable sheets, the sheets layered and at least some of the
sheets pleated to provide a plurality of groups of channels
extending through the core, each of the plurality of groups of
channels comprising channels defined between two adjacent ones of
the sheets and extending along the pleats of at least one of the
pleated sheets, [0103] a plurality of plenums formed on opposed
sides of the core, the plenums on each of the opposed sides of the
core configured such that the channels of groups of channels on
opposing sides of the same one of the sheets are fluidly connected
to different ones of the plenums; [0104] wherein the plenums are
defined at least in part by manifold members attached along
opposite edges of the sheets, at least one of the manifold members
comprising a sheet that is connected to and follows an edge of one
of the pleated water vapor-permeable sheets. [0105] 2. A heat and
humidity exchanger according to example enumerated embodiment 1
wherein the manifold members comprise sheets of material that are
ribbed on at least one side. [0106] 3. A heat and humidity
exchanger according to example enumerated embodiment 2 wherein the
manifold members comprise sheets of material that are ribbed on two
opposing sides. [0107] 4. A heat and humidity exchanger according
to example enumerated embodiment 2 wherein the manifold members are
triangular in plan view and the ribs extend from close to the
attached edge of the manifold members toward an open edge of the
manifold member. [0108] 5. A heat and humidity exchanger according
to any one of example enumerated embodiments 1 to 4 wherein the
manifold members comprise sheets of material having a thickness not
exceeding 0.012 inches. [0109] 6. A heat and humidity exchanger
according to any one of example enumerated embodiments 1 to 5
wherein the manifold members comprise a water vapor-permeable
material. [0110] 7. A heat and humidity exchanger according to
example enumerated embodiment 6 wherein the manifold members are
made of the same material as the water vapor-permeable membrane
sheets. [0111] 8. A heat and humidity exchanger according to any
one of example enumerated embodiments 1 to 7 wherein the manifold
members are stiffer than the water vapor-permeable membrane sheets.
[0112] 9. A heat and humidity exchanger according to example
enumerated embodiment 8 wherein the manifold members comprise a
thermally-conductive material. [0113] 10. A heat and humidity
exchanger according to any one of example enumerated embodiments 1
to 6 wherein the manifold members comprise a material that is
different from a material of the water vapor-permeable sheets.
[0114] 11. A heat and humidity exchanger according to example
enumerated embodiment 10 wherein the manifold members comprise a
thermoformed plastic material. [0115] 12. A heat and humidity
exchanger according to any one of example enumerated embodiments 1
to 11 wherein manifold members comprise a fire-retardant material.
[0116] 13. A heat and humidity exchanger according to any one of
example enumerated embodiments 1 to 12 wherein the manifold members
attached to the pleated water vapor-permeable sheets have edges
formed to follow the pleats of the pleated sheets and a transition
zone wherein the manifold members gradually become flatter with
distance from the edges of the manifold members. [0117] 14. A heat
and humidity exchanger according to any one of example enumerated
embodiments 1 to 13 wherein the manifold members comprise a frame
extending around periphery of the water vapor-permeable membrane
sheet to which the manifold member is attached. [0118] 15. A heat
and humidity exchanger according to any one of example enumerated
embodiments 1 to 14 wherein the pleated water vapor-permeable
sheets are glued to the adjacent water vapor-permeable sheets.
[0119] 16. A heat and humidity exchanger according to example
enumerated embodiment 15 wherein the glue is a water-permeable
glue. [0120] 17. A heat and humidity exchanger according to example
enumerated embodiment 15 wherein the core is self-supporting.
[0121] 18. A heat and humidity exchanger according to any one of
example enumerated embodiments 1 to 17 wherein the core is made up
of alternating flat water vapor-permeable membrane sheets and
pleated water vapor-permeable membrane sheets. [0122] 19. A heat
and humidity exchanger according to example enumerated embodiment
18 wherein the flat membrane sheets extend between manifold members
attached to adjacent pleated sheets to separate adjacent plenums.
[0123] 20. A heat and humidity exchanger according to example
enumerated embodiment 19 wherein the manifold members comprise
sheets of material that are ribbed on two opposing sides and the
flat water vapor-permeable membrane sheets are supported between
ribs of the adjacent manifold members. [0124] 21. A heat and
humidity exchanger according to any one of example enumerated
embodiments 18 to 20 wherein the channels are triangular in
cross-section. [0125] 22. A heat and humidity exchanger according
to example enumerated embodiment 21 wherein the pleated water
vapor-permeable sheets have pleat angles of
60.degree..+-.15.degree.. [0126] 23. A heat and humidity exchanger
according to example enumerated embodiment 22 wherein the channels
have heights of 4.5.+-.2.5 mm. [0127] 24. A heat and humidity
exchanger according to any one of example enumerated embodiments 1
to 23 wherein the pleated water vapor-permeable sheets are attached
to adjacent water vapor-permeable sheets along folds of the pleated
water vapor-permeable sheets. [0128] 25. A heat and humidity
exchanger according to example enumerated embodiment 24 wherein the
pleated water vapor-permeable sheets are formed with flattened
crests. [0129] 26. A heat and humidity exchanger according to any
one of example enumerated embodiments 1 to 17 wherein the channels
are defined between adjacent pleated water vapor-permeable sheets
and crests of the adjacent water vapor-permeable pleated sheets are
attached to one another. [0130] 27. A heat and humidity exchanger
according to one of example enumerated embodiments 1 to 17 or 26
wherein the plurality of channels are quadrilateral in
cross-section. [0131] 28. A heat and humidity exchanger according
to example enumerated embodiment 27 wherein the plurality of
channels are square or rectangular in cross-section. [0132] 29. A
heat and humidity exchanger according to example enumerated
embodiment 27 wherein the plurality of channels are diamond-shaped
in cross-section. [0133] 30. A heat and humidity exchanger
according to any one of example enumerated embodiments 1 to 29
comprising a sealant material sealing faces of the core that extend
parallel to the channels. [0134] 31. A heat and humidity exchanger
according to any one of example enumerated embodiments 1 to 29
wherein the water vapor-permeable sheets of the core are sealed to
adjacent water vapor-permeable sheets along edges of the sheets
extending parallel to the channels. [0135] 32. A heat and humidity
exchanger according to any one of example enumerated embodiments 1
to 31 wherein the plenums are connected to carry first and second
fluid flows through the channels of the core such that the first
and second flows are carried in alternating ones of the groups of
channels and the first and second flows flow in opposing directions
through the core. [0136] 33. A heat and humidity exchanger
according to any one of example enumerated embodiments 1 to 32
wherein a first group of the plurality of channels extends from a
first plenum through the core to a second plenum, a second group of
the plurality of channels extends from a third plenum through the
core to a fourth plenum, each of the plurality of channels in the
first group have walls in common with a plurality of the channels
of the second group and each of the plurality of channels in the
second group have walls in common with a plurality of the channels
of the first group. [0137] 34. A heat and humidity exchanger
according to any one of example enumerated embodiments 1 to 33
wherein each of the channels comprises a plurality of walls and
each of the channel walls is water vapor-permeable. [0138] 35. A
heat and humidity exchanger according to any one of example
enumerated embodiments 1 to 34 wherein for at least a plurality of
the channels in a plurality of the groups each of the water
vapor-permeable walls is in common with another channel belonging
to a different one of the groups of channels. [0139] 36. An energy
recovery ventilator for a building comprising a heat and humidity
exchanger according to any one of example enumerated embodiments 1
to 35. [0140] 37. Use of a heat and humidity exchanger according to
any one of example enumerated embodiments 1 to 35 for exchanging
heat and humidity between a flow of fresh air entering a building
and a flow of air exiting the building. [0141] 38. A heat and
humidity exchanger comprising: [0142] a core comprising a plurality
of channels, a first group of the plurality of channels extending
from a first plenum through the core to a second plenum, a second
group of the plurality of channels extending from a third plenum
through the core to a fourth plenum, each of the plurality of
channels in the first group having walls in common with a plurality
of the channels of the second group and each of the plurality of
channels in the second group having walls in common with a
plurality of the channels of the first group; [0143] the plurality
of channels defined by a plurality of water vapor-permeable
membrane sheets, at least one of the water vapor-permeable membrane
sheets being pleated, the pleated water vapor-permeable membrane
sheet defining a plurality of the walls of each of a plurality of
the first group of channels; [0144] wherein the first and fourth
plenums are separated at least in part by a manifold sheet that is
connected to and follows an edge of the pleated water
vapor-permeable membrane sheet. [0145] 39. A heat and humidity
exchanger according to example enumerated embodiment 38 wherein the
second and third plenums are separated at least in part by a second
manifold sheet that is connected to and follows an edge of the
pleated water vapor-permeable membrane sheet. [0146] 40. A heat and
humidity exchanger according to example enumerated embodiment 38 or
39 wherein the channels of the first and second groups of channels
are straight and parallel to one another. [0147] 41. A heat and
humidity exchanger according to any one of example enumerated
embodiments 38 to 40 wherein the plenums are defined at least in
part by manifold members attached to the water vapor-permeable
membrane sheets of the core and the manifold members comprise
sheets of material that are ribbed on at least one side. [0148] 42.
A heat and humidity exchanger according to example enumerated
embodiment 41 wherein the manifold members comprise sheets of
material that are ribbed on two opposing sides. [0149] 43. A heat
and humidity exchanger according to any of example enumerated
embodiments 41 to 42 wherein the manifold members are triangular in
plan view and the ribs extend from close to the attached edge of
the manifold members toward an open edge of the manifold member.
[0150] 44. A heat and humidity exchanger according to any one of
example enumerated embodiments 41 to 43 wherein, the manifold
members provide separating portions that separate adjacent ones of
the plenums and the separating portions comprise sheets of material
having a thickness not exceeding 0.012 inches. [0151] 45. A heat
and humidity exchanger according to any one of example enumerated
embodiments 41 to 44 wherein the manifold members comprise a water
vapor-permeable material. [0152] 46. A heat and humidity exchanger
according to example enumerated embodiment 45 wherein the manifold
members are made of the same material as the water vapor-permeable
membrane sheets. [0153] 47. A heat and humidity exchanger according
to any one of example enumerated embodiments 41 to 46 wherein the
manifold members are stiffer than the water vapor-permeable
membrane sheets. [0154] 48. A heat and humidity exchanger according
to example enumerated embodiment 47 wherein the manifold members
comprise a thermally-conductive material. [0155] 49. A heat and
humidity exchanger according to any one of example enumerated
embodiments 41 to 45 wherein the manifold members comprise a
material that is different from a material of the water
vapor-permeable sheets. [0156] 50. A heat and humidity exchanger
according to any one of example enumerated embodiments 41 to 44
wherein the manifold members comprise a thermoformed plastic
material. [0157] 51. A heat and humidity exchanger according to any
one of example enumerated embodiments 41 to 50 wherein the manifold
members comprise a fire-retardant material. [0158] 52. A heat and
humidity exchanger according to any one of example enumerated
embodiments 41 to 51 wherein the manifold members attached to the
pleated water vapor-permeable sheets have edges formed to follow
the pleats of the pleated sheets and a transition zone wherein the
manifold members gradually become flatter with distance from the
edges of the manifold members. [0159] 53. A heat and humidity
exchanger according to any one of example enumerated embodiments 41
to 52 wherein the manifold members comprise a frame extending
around periphery of the water vapor-permeable membrane sheet to
which the manifold member is attached. [0160] 54. A heat and
humidity exchanger according to any one of example enumerated
embodiments 38 to 53 wherein the pleated water vapor-permeable
sheets are glued to the adjacent water vapor-permeable sheets.
[0161] 55. A heat and humidity exchanger according to example
enumerated embodiment 54 wherein the pleated water vapor-permeable
sheets are glued to the adjacent water vapor-permeable sheets by a
water-permeable glue. [0162] 56. A heat and humidity exchanger
according to example enumerated embodiment 54 wherein the core is
self-supporting. [0163] 57. A heat and humidity exchanger according
to any one of example enumerated embodiments 38 to 56 wherein the
core is made up of alternating flat water vapor-permeable membrane
sheets and pleated water vapor-permeable membrane sheets. [0164]
58. A heat and humidity exchanger according to example enumerated
embodiment 57 wherein the flat membrane sheets extend between
manifold members attached to adjacent pleated sheets to separate
adjacent plenums. [0165] 59. A heat and humidity exchanger
according to example enumerated embodiment 58 wherein the manifold
members comprise sheets of material that are ribbed on two opposing
sides and the flat water vapor-permeable membrane sheets are
supported between ribs of the adjacent manifold members. [0166] 60.
A heat and humidity exchanger according to example enumerated
embodiment 57 wherein the channels are triangular in
cross-section.
[0167] 61. A heat and humidity exchanger according to example
enumerated embodiment 60 wherein the pleated water vapor-permeable
sheets have pleat angles of 60.degree..+-.15.degree.. [0168] 62. A
heat and humidity exchanger according to example enumerated
embodiment 61 wherein the channels have heights of 4.5.+-.2.5 mm.
[0169] 63. A heat and humidity exchanger according to any one of
example enumerated embodiments 38 to 62 wherein the pleated water
vapor-permeable sheets are attached to adjacent water
vapor-permeable sheets along folds of the pleats. [0170] 64. A heat
and humidity exchanger according to example enumerated embodiment
63 wherein the pleated water vapor-permeable sheets are configured
with pleats having flattened crests. [0171] 65. A heat and humidity
exchanger according to any one of example enumerated embodiments 38
to 64 wherein the channels are defined between adjacent pleated
water vapor-permeable sheets and crests of the adjacent water
vapor-permeable pleated sheets are attached to one another. [0172]
66. A heat and humidity exchanger according to example enumerated
embodiment 38 wherein the plurality of channels are quadrilateral
in cross-section. [0173] 67. A heat and humidity exchanger
according to example enumerated embodiment 66 wherein the plurality
of channels are square or rectangular in cross-section. [0174] 68.
A heat and humidity exchanger according to example enumerated
embodiment 66 wherein the plurality of channels are diamond-shaped
in cross-section. [0175] 69. A heat and humidity exchanger
according to any one of example enumerated embodiments 38 to 68
comprising a sealant material sealing faces of the core that extend
parallel to the channels. [0176] 70. A heat and humidity exchanger
according to any one of example enumerated embodiments 38 to 68
wherein the water vapor-permeable sheets of the core are sealed to
adjacent water vapor-permeable sheets of the core along edges of
the sheets extending parallel to the channels. [0177] 71. A heat
and humidity exchanger according to any one of example enumerated
embodiments 38 to 68 wherein the plenums are connected to carry
first and second fluid flows through the channels of the core such
that the channels carrying the first flow are separated from
channels carrying the second flow by the water vapor permeable
membrane sheets of the core. [0178] 72. A heat and humidity
exchanger according to any one of example enumerated embodiments 38
to 71 wherein a first group of the plurality of channels extends
from a first plenum through the core to a second plenum, a second
group of the plurality of channels extends from a third plenum
through the core to a fourth plenum, each of the plurality of
channels in the first group have walls in common with a plurality
of the channels of the second group and each of the plurality of
channels in the second group have walls in common with a plurality
of the channels of the first group. [0179] 73. A heat and humidity
exchanger according to any one of example enumerated embodiments 38
to 71 wherein each of the channels comprises a plurality of walls
and each of the channel walls is water vapor-permeable. [0180] 74.
A heat and humidity exchanger according to any one of example
enumerated embodiments 38 to 71 wherein the core is formed from a
plurality of layers, and each of the plurality of layers is
self-supporting. [0181] 75. A heat and humidity exchanger according
to example enumerated embodiment 74 wherein each of the plurality
of layers comprises one of the water vapor permeable membrane
sheets attached to one or more manifold members. [0182] 76. A heat
and humidity exchanger according to example enumerated embodiment
75 wherein each of the plurality of layers comprises a pleated
water vapor permeable membrane sheets attached along folds to
another water vapor permeable membrane sheet. [0183] 77. An energy
recovery ventilator for a building comprising a heat and humidity
exchanger according to any one of example enumerated embodiments 38
to 76. [0184] 78. Use of a heat and humidity exchanger according to
any one of example enumerated embodiments 38 to 76 for exchanging
heat and humidity between a flow of fresh air entering a building
and a flow of air exiting the building. [0185] 79. A heat and
humidity exchanger comprising: [0186] a core comprising a plurality
of channels each having a triangular cross-section, a first group
of the plurality of channels extending from a first plenum through
the core to a second plenum, a second group of the plurality of
channels extending from a third plenum through the core to a fourth
plenum, each of the plurality of channels in the first group having
walls in common with a plurality of the channels of the second
group and each of the plurality of channels in the second group
having walls in common with a plurality of the channels of the
first group, each of the common walls being water vapor-permeable.
[0187] 80. A heat and humidity exchanger according to example
enumerated embodiment 79 wherein the channels of the first and
second groups of channels are straight and parallel to one another.
[0188] 81. A heat and humidity exchanger according to any one of
example enumerated embodiments 79 or 80 wherein the core comprises
a plurality of vapor-permeable membrane stacked vapor-permeable
membrane sheets and the plenums are defined at least in part by
manifold members attached to the water vapor-permeable membrane
sheets of the core. [0189] 82. A heat and humidity exchanger
according to example enumerated embodiment 81 wherein the manifold
members comprise sheets of material that are ribbed on at least one
side. [0190] 83. A heat and humidity exchanger according to example
enumerated embodiment 82 wherein the manifold members comprise
sheets of material that are ribbed on two opposing sides. [0191]
84. A heat and humidity exchanger according to any of example
enumerated embodiments 82 to 83 wherein the manifold members are
triangular in plan view and the ribs extend from close to the
attached edge of the manifold members toward an open edge of the
manifold member. [0192] 85. A heat and humidity exchanger according
to any of example enumerated embodiments 82 to 84 wherein the
manifold members are each connected to the core along a first edge,
have an up-turned wall along a second edge and a down-turned wall
along a third edge such that, when stacked together the manifold
members form a stack of plenums that open alternately to sides
corresponding to the first and second edges [0193] 86. A heat and
humidity exchanger according to any one of example enumerated
embodiments 81 to 85 wherein, the manifold members provide
separating portions that separate adjacent ones of the plenums and
the separating portions comprise sheets of material having a
thickness not exceeding 0.012 inches. [0194] 87. A heat and
humidity exchanger according to any one of example enumerated
embodiments 81 to 86 wherein the manifold members comprise a water
vapor-permeable material. [0195] 88. A heat and humidity exchanger
according to any one of example enumerated embodiments 81 to 86
wherein the manifold members are made of the same material as the
water vapor-permeable membrane sheets. [0196] 89. A heat and
humidity exchanger according to any one of example enumerated
embodiments 81 to 88 wherein the manifold members are stiffer than
the water vapor-permeable membrane sheets. [0197] 90. A heat and
humidity exchanger according to any one of example enumerated
embodiments 81 to 86 wherein the manifold members comprise a
material that is different from a material of the water
vapor-permeable sheets. [0198] 91. A heat and humidity exchanger
according to example enumerated embodiment 90 wherein the manifold
members comprise a thermoformed plastic material. [0199] 92. A heat
and humidity exchanger according to any one of example enumerated
embodiments 81 to 91 wherein the manifold members comprise a
fire-retardant material. [0200] 93. A heat and humidity exchanger
according to any one of example enumerated embodiments 81 to 92
wherein the core comprises a plurality of pleated water vapor
permeable membrane sheets and manifold members attached to the
pleated water vapor-permeable sheets have edges formed to follow
the pleats of the pleated sheets and a transition zone wherein the
manifold members gradually become flatter with distance from the
edges of the manifold members. [0201] 94. A heat and humidity
exchanger according to any one of example enumerated embodiments 81
to 93 wherein the manifold members comprise a frame extending
around periphery of the water vapor-permeable membrane sheet to
which the manifold member is attached. [0202] 95. A heat and
humidity exchanger according to example enumerated embodiment 93
wherein the pleated water vapor-permeable sheets are glued to the
adjacent water vapor-permeable sheets. [0203] 96. A heat and
humidity exchanger according to example enumerated embodiment 95
wherein the pleated water vapor-permeable sheets are glued to the
adjacent water vapor-permeable sheets by a water-permeable glue.
[0204] 97. A heat and humidity exchanger according to any one of
example enumerated embodiments 79 to 95 wherein the core is
self-supporting. [0205] 98. A heat and humidity exchanger according
to example enumerated embodiment 97 wherein the core is made up of
alternating flat water vapor-permeable membrane sheets and pleated
water vapor-permeable membrane sheets. [0206] 99. A heat and
humidity exchanger according to example enumerated embodiment 98
wherein the flat membrane sheets extend between manifold members
attached to adjacent pleated sheets to separate adjacent plenums.
[0207] 100. A heat and humidity exchanger according to example
enumerated embodiment 99 wherein the manifold members comprise
sheets of material that are ribbed on two opposing sides and the
flat water vapor-permeable membrane sheets are supported between
ribs of the adjacent manifold members. [0208] 101. A heat and
humidity exchanger according to any one of example enumerated
embodiments 79 to 100 wherein the channels have heights of
4.5.+-.2.5 mm. [0209] 102. An energy recovery ventilator for a
building comprising a heat and humidity exchanger according to any
one of example enumerated embodiments 79 to 101. [0210] 103. Use of
a heat and humidity exchanger according to any one of example
enumerated embodiments 79 to 101 for exchanging heat and humidity
between a flow of fresh air entering a building and a flow of air
exiting the building. [0211] 104. A heat and water vapor exchanger
comprising: [0212] a core structure comprising a plurality of
layered water vapor permeable sheets attached together to form a
self-supporting structure, a plurality of the layered water vapor
permeable sheets being pleated such that triangular channels extend
through the core; [0213] a manifold structure comprising manifold
members attached along edges of the vapor permeable membrane sheets
of the core, the manifold members forming stacked plenums such that
channels extending through the core between different pairs of
adjacent ones of the water vapor permeable membrane sheets are in
fluid communication with different ones of the plenums. [0214] 105.
A heat and water vapor exchanger according to example enumerated
embodiment 104 wherein the core comprises a stack of pleated sheets
of water vapor permeable membrane alternating with flat sheets of
water vapor permeable membrane. [0215] 106. A heat and water vapor
exchanger according to example enumerated embodiment 104 or 105
wherein the manifold members are of a material different from that
of the water vapor permeable membrane sheets.
Interpretation of Terms
[0216] Unless the context clearly requires otherwise, throughout
the description and the claims: [0217] "comprise," "comprising,"
and the like are to be construed in an inclusive sense, as opposed
to an exclusive or exhaustive sense; that is to say, in the sense
of "including, but not limited to". [0218] "connected," "coupled,"
or any variant thereof, means any connection or coupling, either
direct or indirect, between two or more elements; the coupling or
connection between the elements can be physical, logical, or a
combination thereof. [0219] "herein," "above," "below," and words
of similar import, when used to describe this specification shall
refer to this specification as a whole and not to any particular
portions of this specification. [0220] "or," in reference to a list
of two or more items, covers all of the following interpretations
of the word: any of the items in the list, all of the items in the
list, and any combination of the items in the list. [0221] the
singular forms "a," "an," and "the" also include the meaning of any
appropriate plural forms.
[0222] Words that indicate directions such as "vertical,"
"transverse," "horizontal," "upward," "downward," "forward,"
"backward," "inward," "outward," "vertical," "transverse," "left,"
"right," "front," "back"," "top," "bottom," "below," "above,"
"under," and the like, used in this description and any
accompanying claims (where present) depend on the specific
orientation of the apparatus described and illustrated. The subject
matter described herein may assume various alternative
orientations. Accordingly, these directional terms are not strictly
defined and should not be interpreted narrowly.
[0223] Where a component (e.g. a core, structure, plenum, fan,
duct, etc.) is referred to above, unless otherwise indicated,
reference to that component (including a reference to a "means")
should be interpreted as including as equivalents of that component
any component which performs the function of the described
component (i.e., that is functionally equivalent), including
components which are not structurally equivalent to the disclosed
structure which performs the function in the illustrated exemplary
embodiments of the invention.
[0224] Specific examples of systems, methods and apparatus have
been described herein for purposes of illustration. These are only
examples. The technology provided herein can be applied to systems
other than the example systems described above. Many alterations,
modifications, additions, omissions and permutations are possible
within the practice of this invention. This invention includes
variations on described embodiments that would be apparent to the
skilled addressee, including variations obtained by: replacing
features, elements and/or acts with equivalent features, elements
and/or acts; mixing and matching of features, elements and/or acts
from different embodiments; combining features, elements and/or
acts from embodiments as described herein with features, elements
and/or acts of other technology; and/or omitting combining
features, elements and/or acts from described embodiments.
[0225] It is therefore intended that the following appended claims
and claims hereafter introduced are interpreted to include all such
modifications, permutations, additions, omissions and
sub-combinations as may reasonably be inferred. 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.
* * * * *