COUNTERFLOW ENERGY RECOVERY VENTILATOR CORE COMPRISING SEAMLESS PLEATED SUPPORT MEDIA

Background

Energy recovery ventilator (ERV) cores are used e.g. to enhance energy efficiency in heating or cooling of buildings, dwellings, and the like.

Summary

In broad summary, herein is disclosed a counterflow energy recovery ventilator core comprising a seamless pleated support media bearing a water-vapor-permselective film that is co-pleated along with the pleated support media. These and other aspects will be apparent from the detailed description below. In no event, however, should this summary be construed to limit the claimable subject matter, whether such subject matter is presented in claims in the application as initially filed or in claims that are amended or otherwise presented in prosecution.

Brief Description of the Drawings

Fig. 1 is a perspective view, generally from the inbound side, of an exemplary ERV core comprising a pleated support media.

Fig. 2 is a conceptual side view, looking along the transverse axis/pleat direction, of an exemplary ERV core.

Fig. 3 is a conceptual side view, looking along the pleat direction, of an exemplary pleated support media of an ERV core.

Fig. 4 is a perspective exploded view, generally from the inbound side, of an exemplary ERV core comprising a pleated support media.

Fig. 5 is a perspective view, generally from the inbound side, of an exemplary pleated support media of an ERV core.

Fig. 6 is a side view, looking along the pleat direction, of an exemplary pleated support media of an ERV core.

Fig. 7 is a magnified isolated view of a pleat tip of the pleated support media of Fig. 6.

Fig. 8 is a magnified isolated view of a portion of the pleated support media of Fig. 6.

Fig. 9 is a is a perspective view, generally from the inbound side, of another exemplary ERV core comprising a pleated support media.

Fig. 10 is a conceptual side view, looking along the transverse axis/pleat direction, of an exemplary pleated support media of an ERV core.

Fig. 11 is a perspective view, generally from the inbound side, of another exemplary pleated support media of an ERV core.

Fig. 12 is a perspective view, generally from the inbound side, of another exemplary pleated support media of an ERV core. Fig. 13 is a perspective view, generally from the inbound side, of an exemplary edge-fed ERV core comprising a pleated support media.

Like reference numbers in the various figures indicate like elements. Some elements may be present in identical or equivalent multiples; in such cases only one or more representative elements may be designated by a reference number but it will be understood that such reference numbers apply to all such identical elements. Unless otherwise indicated, all figures and drawings in this document are not to scale and are chosen for the purpose of illustrating different embodiments of the invention. In particular the dimensions of the various components are depicted in illustrative terms only, and no relationship between the dimensions of the various components should be inferred from the drawings, unless so indicated.

Glossary

Although terms such as “first” and “second” may be used in this disclosure, it should be understood that those terms are used in their relative sense only unless otherwise noted. As used herein as a modifier to a property or attribute, the term “generally”, unless otherwise specifically defined, means that the property or attribute would be readily recognizable by a person of ordinary skill but without requiring absolute precision or a perfect match (e.g., within +/- 20 % for quantifiable properties). The term “substantially”, unless otherwise specifically defined, means to a high degree of approximation (e.g., within +/- 10% for quantifiable properties) but again without requiring absolute precision or a perfect match. The term “essentially” means to a very high degree of approximation (e.g., within plus or minus 2 % for quantifiable properties); it will be understood that the phrase “at least essentially” subsumes the specific case of an “exact” match. However, even an “exact” match, or any other characterization using terms such as e.g. same, equal, identical, uniform, constant, and the like, will be understood to be within the usual tolerances or measuring error applicable to the particular circumstance rather than requiring absolute precision or a perfect match.

The terms “inbound” and “outbound” are used herein with reference to a building that an ERV core is installed in. Inbound refers to the side and components of the core that handles air that is entering the building (sometimes referred to as “makeup” air); outbound refers to the side and components of the core that handles air that is leaving the building (sometimes referred to as “exhaust” air), e.g. to an outside environment. The terms “entrance” and “exit” are used with regard to the ERV core itself. That is, the inbound side of the core will have an inbound air entrance for inbound air to enter the core and an inbound air exit for inbound air to leave the core; the outbound side of the core will similarly have an outbound air entrance and an outbound air exit. The inbound and outbound sides of ERV cores and pleated support media thereof, and inbound and outbound entrances and exits, are indicated on various Figures as discussed in detail later herein. In the Figures, the inbound and outbound sides are typically shown respectively uppermost and lowermost; however, it will be appreciated that an ERV core may be positioned in any orientation.

The term Pleat Direction (D _p on various Figures) denotes a direction parallel to the long axis of the pleats of a pleated media of an ERV core, e.g. as indicated in Figs. 1 and 5. The term “transverse” denotes a direction aligned with the Pleat Direction of the pleated media. As indicated in Fig. 5, the pleated media will have a longitudinal axis Lo that is perpendicular to the Pleat Direction/transverse axis. The terms longitudinal and transverse are used for ease of description; use of these terms does not imply that the length (L, in Fig. 5) of a pleated media in the longitudinal direction must necessarily be greater than the width (W, in Fig. 5) of the pleated media along its transverse direction. As indicated in Fig. 6, the pleated media will also have a depth direction (D) that is perpendicular to the longitudinal direction Lo and to the Pleat Direction/transverse axis, as indicated in Fig. 6. Other parameters of the pleated media (e.g. pleat height P _H and pleat spacing Ps) are indicated in Fig. 6 and are discussed in detail later herein.

By “occlude”, “occluded”, “occlusive”, and like terms, is meant to block so that air cannot pass therethrough. By definition, a film that is occlusive is an impermeable, nonporous film.

By “porous” is meant a layer of media (e.g. a fibrous web) that comprises through-passages that allow air and water vapor to enter a major face of the layer, travel through the layer, and exit the opposing major face of the layer. By definition, a film that is porous is not an occlusive or impermeable film.

By water- vapor-permselective is meant a film that exhibits a high moisture vapor transmission rate (MVTR) but is essentially impermeable to liquid water and to air and constituents thereof.

Detailed Description

Shown in Fig. 1 in perspective view is an exemplary counterflow energy recovery ventilator (ERV) core 1. Ordinary artisans will be familiar with ERV cores, which are used to exchange thermal energy and water vapor between moving airstreams, while preventing any significant exchange of air (and any particulate and/or gaseous components therein) between the moving airstreams. Often, such cores are used in air exchange systems for buildings or sections of buildings (e.g. residences, homes, apartments, office buildings, etc.), in order to transfer thermal energy and water vapor e.g. from the outbound air into the inbound air, thereby reducing the need to condition the inbound air to modify its temperature and humidity toward a desired level. For example, in wintertime, the temperature and humidity of the inbound air can be increased; conversely, in summertime, the temperature and humidity of the inbound air can be reduced by transfer of thermal energy and water vapor to the outbound air. The use of an ERV core in an air exchange system of a building can thus reduce the load on the heating/ventilation/air conditioning (HVAC) system of the building. ERV cores and like articles and apparatus, and their principles of operation, are described e.g. in U.S. Patents 4040804, 9517433, and 9562726, all of which are incorporated by reference in their entirety herein for this purpose.

A herein-disclosed ERV core relies on a layer of pleated support media 10, shown in isolated side view (looking along the Pleat Direction) in Fig. 3. As indicated in Fig. 3, inbound air flows along channels provided by inbound pleat valleys 32, while outbound air flows along channels provided by outbound pleat valleys 22, in a direction opposite to that of the inbound air (i.e., in a counterflow configuration, as shown conceptually in Fig. 2). As the air flows along these channels, thermal energy and water vapor are transferred through pleat walls 30. A water-vapor-permselective film 50 is provided (typically, laminated to a major surface of support media 10) in order to accomplish this. By water-vapor-permselective is meant that film 50 exhibits a high moisture vapor transmission rate (MVTR) but is essentially impermeable to liquid water and to air and major constituents thereof (e.g. nitrogen and oxygen).

In many embodiments the pleated support media 10 may be a porous material, chosen to ensure that support media 10 does not present a significant barrier to transport of water vapor (and thermal energy) therethrough. Support media 10 may be chosen from any material that is suitably water-vapor-transmissive and that is amenable to being pleated, and to which a permselective film 50 can be attached e.g. by lamination. As disclosed herein, the permselective film 50 is laminated to the support media 10 after which the support media 10 bearing film 50 thereon is pleated. Support media 10 and film 50 will thus be in a co pleated configuration in which they are both pleated according to the same pleat spacing, pleat height, and other geometric characteristics, and are locally parallel to each other throughout their extent, as is evident e.g. from Fig. 3.

As indicated in Fig. 3, inbound air flows along channels provided by inbound pleat valleys 32, while outbound air flows along channels provided by outbound pleat valleys 22. (In this and other Figures, inbound air is denoted by an open circle with outbound air being denoted by a filled circle.) As indicated in Fig. 1, entering inbound air (I _EN ) may reach these channels through an inbound air entrance 2 and may leave these channels (as exiting inbound air I _EX ) through an inbound air exit 3. Such an arrangement may be provided by using an inbound facing 71 (e.g. any suitable impermeable film, impermeable in this instance meaning impermeable to water vapor as well as liquid water and air) that occlusively covers inbound pleat valleys 32 to form flow channels, while leaving inbound entrance 2 and exit 3 accessible. In many embodiments such a facing 71 may be e.g. bonded to the inbound pleat tips 31 and may be at least generally planar when viewed along the Pleat Direction (as will be evident from Fig. 1).

Similar arrangements may be made on the outbound side. That is, an impermeable outbound facing 72 may occlusively cover outbound pleat valleys 22 while leaving outbound entrance 4 and exit 5 accessible for flow of entering outbound air OEN and of exiting outbound air OEX, as generally indicated in Figs. 1 and 2. Such counterflow arrangements will be readily understood by ordinary artisans.

An ERV core configured in the general manner described above and depicted in Figs. 1 and 2 will be referred to herein as side-fed core. By this is meant that air enters the core from major sides of the core, e.g. in a direction that is generally perpendicular to the pleat valleys/flow channels 22 and 32. The air thus must make a turn to flow down the flow channels. Such side-fed arrangements are contrasted to edge-fed arrangements, which are discussed in detail later herein.

An exemplary side-fed core arrangement is shown in exploded view in Fig. 4. As evident from Fig. 4 (and as also depicted in Fig. 1), in such an arrangement, the corrugated edges 15 and 16 of pleated support media 10 may be covered by facings (e.g., impermeable films) 75 and 76 in order to occlude (seal) the edges. Other arrangements are possible, as discussed later herein. Non-corrugated edges 17 and 18 may also be covered with facings 77 and 78 as indicated in Fig. 4. In some embodiments, inbound and outbound facings 71 and 72, and non-corrugated edge facings 77 and 78, may all be portions of a single, continuous casing 70 that is wrapped around the entirety of the longitudinal length (L) of pleated media 10. Such a casing may exhibit a width that is less than the transverse width (W) of pleated media 10, in order that inbound and outbound entrances and exits 2, 3, 4 and 5 can be provided as discussed above.

Thus in some embodiments an occlusive casing 70 may be fitted onto (e.g. wrapped around) support media 10 after media 10 (and permselective film 50) have been pleated and stabilized in the pleated configuration. That is, media 10 and film 50 may be formed into a “pleat pack” of the desired size and shape, after which a casing 70 may be applied thereto. (Also, occlusive facings 75 and 76 may be applied to corrugated edges 15 and 16 of the pleat pack.) Such a casing may be made of any suitable material, e.g. plastic film, molded plastic, and the like. A material such as e.g. paperboard may be used as long as it is sufficiently occlusive (many such paperboards are available with coatings of e.g. wax or clay, which can provide an occlusive layer). In various embodiments, any such facing and/or casing may be comprised of common barrier materials such as e.g. poly (ethylene terephthalate), biaxially-oriented polypropylene, and the like.

Further details of pleated support media 10 will be discussed with reference to Figs. 5 and 6, which are isolated perspective and side views of media 10, with other components (permselective film 50, and facings and so on) omitted for clarity. As noted, pleated media 10 will comprise a set of oppositely-oriented pleats 20 with pleat walls 30 through which water vapor and thermal energy will be transferred. Pleated media 10 will comprise an inbound side 11 and major inbound surface 12, an outbound side 13 and major outbound surface 14, corrugated edges 15 and 16, and non-corrugated edges 17 and 18. Inbound side 11 of pleated media 10 will comprise inbound pleat valleys 32 which provide flow channels for inbound air, and inbound pleat tips 31; outbound side 13 will similarly comprise outbound pleat valleys/flow channels 22 and outbound pleat tips 21.

The longitudinal axis Lo and length L of pleated media 10 along axis Lo, and the transverse axis T and width W of pleated media 10 along axis T, are pointed out in Fig. 5; the depth axis D of pleated media 10 (which is typically perpendicular to axes Lo and T) is indicated in Fig. 6. In many embodiments pleated support media 10 (and ERV core 1 as a whole) may be rectangular in shape (which specifically includes square shapes) with e.g. four comers; in such embodiments pleated media 10 may thus have a generally rectangular perimeter (which does not preclude irregularities, notches, chamfered or angled comers, or the like, in the perimeter of media 10).

Further details of pleat geometry are discussed with reference to the side view of Fig. 6. Pleat spacing and pleat height are evaluated with the pleated media 10 in a nominally planar configuration in which the pleated media 10 exhibits a readily recognizable overall major plane (notwithstanding the local deviations from this plane that are inherent in each pleat), as in Fig. 6. The pleat height (pleat amplitude) is the distance (P _h in Fig . 6) from an outbound pleat tip 21 to an inbound pleat tip 31 , along the depth direction D as indicated in Fig. 6. In various embodiments, the pleat height of media 10 may be at least about 2, 4, 6, 8, 10, or 12 mm. In further embodiments, the pleat height may be at most about 200, 100, 80, 60, 40, 30, 20, or 10 mm. The pleat spacing (P _s in Fig. 6) is the distance between nearest-neighbor same-side pleat tips, along the longitudinal direction Di of the pleated media. Pleated media 10 may comprise any suitable pleat spacing. In various embodiments the pleat spacing may be at most about 20, 15, 10, 8, 6, 4, 3, or 2 mm; in further embodiments the pleat spacing may be at least about 1, 2, 3, 4, 5, 6, 8, or 10 mm.

The pleated media may also be characterized by the radius of curvature R _c of the pleat tips, as depicted in the magnified view of an exemplary pleat tip in Fig. 7. In some embodiments the pleat tips of pleated media 10 may have an average radius of curvature that is less than about 3 mm. In various embodiments, such pleats may comprise tips with an average radius of curvature of at most about 2.5, 2.0, 1.5, 1.0, or 0.5 mm. In some embodiments media 10 may be tightly pleated, meaning that the pleat tips exhibit a very small radius of curvature and the pleat spacing is very small, both in comparison to the pleat height. In various embodiments, the pleated media 10 may exhibit a pleat tip radius of curvature that is less than about 2 mm, and/or a pleat spacing that is less than about 4 mm, and/or a pleat height that is from about 6 mm to about 50 mm. Even in instances in which, for example, media 10 is tightly pleated, in some embodiments the media may be configured so that adjacent walls of pleats are not substantially parallel to each other (i.e., are not aligned within plus or minus 5 degrees of each other) over at least about 70, 80 or even 90 % of the pleat height, on average. Such arrangements can be contrasted to arrangements in which pleat walls are parallel over essentially the entirety ofthe pleat height, e.g. as depicted in the figures of U.S. Patents 4040804 and 9562726. While the above discussions mention tightly-pleated media, it is emphasized that in some embodiments the pleated media may exhibit a much more gentle (e.g. generally sinusoidal or corrugated) pleated configuration.

In various embodiments, support media 10 may comprise a thickness (“t”, as denoted in Fig. 7) of less than about 2.0, 1.5, 1.0, 0.8, 0.6, or 0.4 mm. In various embodiments, the support media may exhibit a basis weight of from at least about 10, 20, or 30 g/m ² , to at most about 100, 80, 60, or 40 g/m ² .

As noted earlier, a water-vapor-permselective film 50 is a film that exhibits a high moisture vapor transmission rate (MVTR) but is essentially impermeable (over any relevant time scale) to liquid water and to air and major constituents thereof (e.g. nitrogen and oxygen). In various embodiments, a water-vapor- permselective film will exhibit an MVTR of at least 1000, 2000, 5000, 8000, 10000, or 15000 grams per square meter per 24 hours, when tested in the general manner set forth in ASTM test method E96M-16. In further embodiments such a film will exhibit an N2 permeation rate of less than 1000, 800, 400, 100, 50 or 10 grams per square meter per day per bar (at 20 °C). In some embodiments a permselective film may exhibit barrier properties toward e.g. nitrogen and oxygen, that are in the same range or greater than those exhibited by common barrier materials such as e.g. poly (ethylene terephthalate), biaxially-oriented polypropylene, and the like. By essentially impermeable to liquid water is meant that the film will not exhibit passage of liquid water (e.g. convective flow of liquid water, the wicking of parcels of liquid water, etc.) over any relevant time scale.

In many embodiments, a water-vapor-permselective film will comprise at least a sublayer that is dense, e .g . is nonporous so that gaseous constituents of air cannot migrate through the sublayer via through- passages that lead from one major surface of the film to the other major surface. For example, in some embodiments a permselective film may take the form of an asymmetric membrane that exhibits a largely porous main body but with a dense skin (e.g. an integral skin) at one surface. In such circumstances, the barrier/permeability properties of the dense sublayer may largely control the overall MVTR and the gas permeability (e.g., the absence thereof) that is exhibited by the entire film. In some embodiments, the entire thickness of the permselective film will be dense (e.g. the film may be a nonporous film as made by extrusion, casting, blow molding, etc.).

In some embodiments permselective film 50 (e.g. a dense film) may take the form of a block copolymer with impermeable hard segments that provide mechanical integrity, and with soft segments that have high chain mobility and are relatively hydrophilic so as to allow water vapor to penetrate therethrough. Such materials are exemplified by, for example, various products available from Arkema under the trade designation PEBAX, which comprise crystalline polyamide hard segments and hydrophilic polyether soft segments. Such materials exhibit excellent MVTR while being relatively impermeable to liquid water and gases. One such material is, for example, PEBAX 1074, which comprises polyamide-12 hard segments and poly(ethylene oxide) soft segments. Many other materials of somewhat similar compositions may also be suitable. Other suitable materials include e.g. polyurethanes (often referred to as thermoplastic polyurethanes or TPUs) that similarly comprise hydrophilic soft segments. Various TPUs are available from Lubrizol under the trade designations PELLETHANE, TECOPHILIC, and TECOFLEX.

It may be advantageous that a permselective film 50 be relatively thin to maximize the ability of water vapor to pass therethrough. In various embodiments, a permselective film may be at most 20, 15, 10, 8, or 6 microns in thickness. In further embodiments, a permselective film may be at least 2, 4, or 5 microns in thickness. The permselective film should have adequate physical properties to allow the film to be attached (e.g. laminated) to support media 10 and to be co-pleated along with support media 10, without unacceptably rupturing or otherwise being damaged in a manner that would compromise its permselective performance. Methods of handling permselective films are discussed in further detail later herein. Permselective film 50 may be disposed on the major inbound surface 12, or the major outbound surface 14, of support media 10. However, in some embodiments it may be advantageous to provide film 50 on the major outbound surface 14 of support media 10, as discussed in detail later herein.

In at least some embodiments, pleated support media 10, as present in an ERV core 1, is seamless. By this is meant that media 10 extends the length and width of the core as a single, continuous piece (Fig. 5 presents an illustrative depiction of a seamless pleated support media). This is contrasted with arrangements in which the media of an ERV core is in the form of multiple pieces, e.g. strips, that are joined together e.g. in the manner disclosed in U.S. Patent 9562726.

Support media 10 may be made of, or include, any suitable material (whether present as a single layer, or as a multilayer media as described later herein) that can support permselective film 50, that does not unduly limit the transport of water vapor (and thermal energy) therethrough, and that is amenable to being pleated and to being maintained in the pleated configuration. Potentially suitable materials may include e.g. paper; porous films of thermoplastic or thermoset materials; microporous membranes such as phase-inversion membranes, organic polymeric nonwoven webs (such as melt blown or spunbond webs, carded webs, wet-laid or air-laid webs, and so on) of synthetic or natural fibers; scrims; woven or knitted materials; foams; fiberglass media; expanded materials or foils, fibrillated materials, or laminates or composites of two or more materials. A nonwoven organic polymeric web comprised of polyethylene, polypropylene or poly (lactic acid) may be suitable, for example. Any suitable method of making a nonwoven web (e.g., melt-blowing, melt-spinning, carding, and so on) may be used. In some embodiments, the nonwoven web may be a blown microfiber (BMF) web; in other embodiments the nonwoven web may be a meltspun web. In various embodiments, support media 10 may exhibit a pressure drop that is less than about 20, 15, 10, 5, or 2 mm of water.

In some embodiments, pleated support media 10 may perform at least one additional function beyond simply supporting permselective film 50. In some such embodiments, pleated support media 10 may be configured to perform channel-filtration of particles from air flowing down the pleat valleys. By channel-filtration is meant a mode of filtration in which at least some particles in an airstream that is moving past support media 10, are captured by support media 10 without the airstream actually flowing through the support media. This will be contrasted with through-filtration, which is a mode of filtration in which an airstream flows through a media (entering one major surface and exiting the other major surface) with particles being captured from the airstream as it flows through the media. It will be appreciated that particle- filtration of the type performed in e.g. HVAC filters, Room Air Purifiers, and so on, is typically through- filtration.

Conventionally, channel-filtration of particles from air (e.g. in HVAC filters and the like) is typically not attempted, due to the relatively low particle-capture rate and filtration performance. However, the present investigations have indicated that, e.g. due to the long, relatively narrow airflow channels provided by pleat valleys, sufficient removal of particles from the moving air can be achieved to make such an arrangement useful. This can be particularly true if the support media is charged so as to be an electret media. In particular, the presence of an electret media may allow fine particles (e.g., so-called PM 2.5 particles) to be removed from the moving airstream.

It will be appreciated that a channel-filtration arrangement which particles are removed from air that is flowing down a channel, by way of the particles being captured by fibers that make up the walls of the channels, is fundamentally different from a through-filtration arrangement in which particles are captured by fibers of a filtration media, as the air actually flows into the media, through the media, and out the other side of the media. It will also be appreciated that present arrangements (involving flow channels provided by a pleated support media) that are macroscopic (e.g. involving cross-sectional areas of tens or even hundreds of square millimeters), differ from filtration arrangements in which e.g. films are provided with microscopic channels in the pm size scale (for example, as described in U.S. Patent 6280824).

Thus, in some embodiments, pleated support media 10 may comprise at least one layer that comprises an electret material for purposes of performing channel-filtration. By an electret material is meant a material (e.g. an organic polymeric material) that, after a suitable charging processes, exhibits a quasi permanent electric charge. The electric charge may be characterized by an X-ray Discharge Test as disclosed e.g. in U.S. Patent Publication No. 2011/0290119. Such charged fibers can be formed into a nonwoven web by any suitable means. In some embodiments, support media 10 can be, or include a layer of, a melt-blown microfiber nonwoven web (e.g. of the general types disclosed in U.S. Patent 4,215,682 and U.S. Patent 7,989,371) or a spunbond nonwoven web, that may include at least some fibers that comprise electrets. Filter media that may be particularly suitable for certain applications might include e.g. media of the general type described in U.S. Patent 8162153 to Fox; media of the general type described in U.S. Patent Application Publication 2008/0038976 to Berrigan; media of the general type described in U.S. Patent Application Publication 2004/0011204 to Both; and media generally known as tribocharged media. Any such media can be charged to provide charged electret moieties if desired. Any suitable charging method may be used, chosen from e.g. corona charging, hydrocharging, tribocharging, and so on. If desired, the media may comprise one or more charging additives, e.g. chosen from any of the additives described in International Patent Publication WO2016/033097. In some embodiments, a media comprising charged electret moieties can also comprise a fluorinated surface treatment e.g. of the type disclosed in U.S. Patent 7887889 to David; such treatments may e.g. improve the performance of the media when exposed to oily mists and the like.

Thus, in some embodiments multilayer media, e.g., laminated media, can be used e.g. so that support media 10 also provides at least some particle filtration and thus functions as a support/filter media. In various embodiments, such media may comprise at least one filtration layer e.g. of any media discussed above (e.g. a meltblown microfiber electret web or a spunbonded electret web) laminated to one or more layers of other material that primarily serves to provide support and pleatability. For example, a plastic netting or mesh, a relatively stiff nonwoven scrim, etc., might be laminated to the filter media (and then pleated along with the media). Any such support media may be laminated together with any such filtration layer by any suitable method, e.g. by melt-bonding, by way of an adhesive (hot melt adhesive, pressure- sensitive adhesive, and so on), calendering or ultrasonic point-bonding, etc.

In particular embodiments a multilayer media may comprise a layer of support media, e.g. a fibrous support media, that primarily serves to provide physical support and to impart enhanced pleatability, in combination with a layer that achieves the above-described channel-filtration. For example, a fiberglass layer, when combined with a particle -filtration layer that is an organic polymeric electret nonwoven web, may allow the pleatability of the resulting laminate to be significantly enhanced over that exhibited by the filtration layer alone. That is, the inclusion of a fiberglass layer can allow an organic polymeric nonwoven web to be pleated to a relatively tight pleat configuration (e.g. a pleat spacing of less than about 3 mm in combination with a pleat height of greater than about 10 mm), in comparison to the organic polymeric nonwoven web alone. (This can be particularly true for e.g. BMF webs, which are characteristically rather soft and limp and thus not amendable to being aggressively pleated.) Fiberglass materials that may be suitable for inclusion in a multilayer support/filter media as disclosed herein include e.g. the products available from Hollingsworth and Vose under the trade designations HF-13732A, HE-14732A, HE-1073, HF-11732A and HF-0121.

A support media 10 (bearing a permselective fdm 50 thereon) may desirably exhibit a relatively high stiffness in order that the support media and fdm 50 can be pleated and can be maintained in the pleated configuration (e.g. without using spacers, separators, or the like, although in some circumstances such items may be used, as discussed later herein). The stiffness of a support media 10 (which, as noted above, may be a single layer, or may take the form of a multilayer support/filter media) may be characterized by the Gurley Stiffness of the layer (measured as described in the Test Methods). In various embodiments, a support media 10 (with or without a permselective film 50, which in many instances may not contribute substantially to the stiffness of the total structure) may exhibit a Gurley Stiffness of at least 200, 300, 400, 600, 800, or 1000 mg.

Particle filtration using channel-filtration as disclosed herein, may be performed on inbound air only, on outbound air only, or on both inbound and outbound air. However, in many embodiments, particle filtration may be performed only on the inbound air. That is, in many embodiments it may be desired to remove e.g. pollen, fine-particle pollutants, and so on, from air that is entering a building. Such considerations may, in some embodiments, dictate the choice of which side of support media 10 permselective film 50 will be disposed on. It will be appreciated that installing permselective film 50 onto a major surface of a support media that is intended to perform channel-filtration of particles, will cover the surface of the support media which may frustrate the effort to perform particle-filtration. Thus in some circumstances it may not be desirable to install permselective film 50 on the major inbound surface 12 of support media 10. However, since in many instances no particle -filtration of outbound air is needed or desired, permselective film 50 can be installed on major outbound surface 14 of support media 10. This can allow permselective film 50 to perform its water-transport function, while not interfering with the ability of support/filter media 10 to filter particles from the inbound air. (It is noted that, even in cases in which support media 10 is not intended to perform particle-filtration, in some embodiments it may be desired to install permselective film 50 on the major inbound surface 12 of support media 10, e.g. to lessen the chance of film 50 being damaged e.g. by any dirt or debris that may happen to enter from the outside environment).

The above-described arrangements enable another potentially advantageous configuration, as shown in exemplary embodiment in Fig. 8. As discussed later herein, a permselective film 50 that is e.g. only a few microns in thickness may be rather fragile. Thus, it may be advantageous to provide a support media 10 with a major surface that is as smooth and uniform as possible in order for film 50 to be laminated thereto without damage to film 50. Thus, in some embodiments a major surface of a fibrous support media 10 to which film 50 is to be bonded, may be e.g. densified so as to convert some of the fibers at that surface, to a more smooth mass with increased uniformity. However, it may not be desirable that the entire thickness of support media 10 be densified in this manner, as this might unduly reduce the ability of water vapor to travel through support media 10. Furthermore, if a surface of fibrous support media 10 that is intended to capture particles is densified in this manner, this might reduce that ability to capture particles. Thus in embodiments of the general type depicted in Fig. 8, the fibers in a zone 44 at or near a major surface of support media 10 to which permselective film 50 is attached (e.g., major outbound surface 14) may be densified, while maintaining the fibers 43 in a majority 42 of the thickness of support media 10 in an undensified condition. In particular, at least the opposing major surface (e.g. major inbound surface 12) may be maintained as a set of fibers that exhibits significant porosity, e.g. to facilitate channel-filtration of particles. Thus in specific embodiments major outbound surface 14 of support media 10 may be densified, with major inbound surface 12 (and, e.g. at least 40, 60, or 80 % of the thickness of support media 10) remaining undensified. By a densified surface of a fibrous support media is meant a surface that exhibits a porosity that is at least 30 % less than that of the opposing, undensified surface of the support media. In many cases, a densified surface can be easily identified simply by visual inspection through an optical microscope. Strictly speaking, a densified surface layer will often be a partially densified layer; that is, the fibers will typically not be completely consolidated (e.g. fully melted and re -solidified) to a fully dense, completely non-porous layer.

Thus, Fig. 8 depicts an arrangement in which support media 10 exhibits a densified layer 44 of fibers, the densified layer comprising major outbound surface 14 of support media 10. Meanwhile, the majority 42 of support media 10, and in particular major inbound surface 12, comprises fibers 43 that are not densified to any significant extent. Surface 14 may thus be amenable to having a permselective film 50 bonded thereto, while surface 12 may be amenable to performing channel-filtration (in particular, at least some fibers 43 near surface 12 may comprise electrets 45).

A major surface of a fibrous support media may be densified e.g. by the application of a heat treatment of suitable time and temperature, e.g. by passing the fibrous support media over a “hot can” or heated drum, through a calendering nip with one of the rolls being heated, etc., so that the fibers at the desired surface are softened (e.g. partially melted) and consolidated. The fibers will thus lose some of their individual character and will rather form an at least partially densified layer. The temperature of the roll, the residence time on the roll, and so on, may be chosen to impart the degree of densification. Ordinary artisans will appreciate that other methods are also possible; however, it may be advantageous that any such method preferentially heat the desired major surface without unduly heating the remainder of the thickness of the support media. In some embodiments, a major surface 14 of a fibrous support media may be densified by non-thermal methods, e.g. by mechanical methods. In some embodiments, a combination of mechanical and thermal methods may be used. In some embodiments, an additive method may be used in which a material is deposited (e.g. sprayed) onto the surface of the fibrous support media in such manner as to partially fill surface cavities and to otherwise enhance the uniformity of the surface. In some embodiments an adhesive (e.g. a spray adhesive) that is used to bond the permselective film to the fibrous support media, may serve such a function in addition to performing the bonding.

In some embodiments, rather than the opposing major surface 12 of the fibrous support media being merely left “as-is” rather than being densified, active steps may be taken to enhance the porosity of this surface and/or to enhance the extent to which fibers at this surface are exposed to the flowing airstream. Thus for example, major surface 12 of the support media might be e.g. fibrillated, needle-tacked, wire- brushed, fluffed, napped, or otherwise treated so as to enhance the extent to which individual fibers are exposed and/or extend from the support media.

A pleated support/filter media that is configured to perform channel-filtration of particles as disclosed herein, will be distinguished from a pleated support media that is not configured to perform channel-filtration of particles. A pleated support/filter media (particularly one that comprises electrets) may be distinguished e.g. by virtue of the Percent Removal (of particles) that is achieved. Percent Removal is a measure of the effectiveness of particle filtration and is evaluated according to the procedure detailed in the Test Methods later herein. In various embodiments, a pleated support/filter media as disclosed herein may perform channel-filtration of particles so as to achieve a Percent Removal of at least 10, 20, 40, 60, 80, 90, 95, or 98.

The above-discussed arrangements in which channel-filtration of particles is performed on inbound air, may be further enhanced by providing a particle filter 80 on entrance 2 through which inbound air (I _EN ) enters the pleat valleys/flow channels, as shown in Fig. 9. While filter 80 may be of any design, in some embodiments filter 80 may serve as a prefilter that is configured to remove coarse particles from the inbound air, with the above-described support/filter media being configured (e.g. comprising electrets) to remove fine particles from the pre-filtered inbound air. Of course, even in embodiments in which support media 10 is not configured to perform any significant particle filtration, a particle filter 80 (of any kind) may be provided on inbound air entrance 2 and/or on inbound air exit 3 if desired.

In some embodiments, a facing (e.g. an inbound facing 71 as described earlier herein) may play a role in particle -filtration rather than e.g. serving only as an impermeable, occlusive film. Thus in some embodiments, such an occlusive facing may comprise a major surface (e.g. that faces inbound flow channels 32) that is configured to perform, or at least assist in, particle filtration. For example, such a major surface may be configured to comprise electrets. In some embodiments, this major surface may have fibers disposed thereon (e.g. by flocking) which fibers may comprise electrets.

In some embodiments, neither inbound pleat valleys 32 nor outbound pleat valleys 22 will comprise any pleat separator or separators therein. By a pleat separator is meant an item that resides in a pleat valley and that prevents the pleat walls from coming too close together or touching. An arrangement in which no pleat separators are present, may be achieved e.g. by suitably choosing the stiffness (e.g. as manifested by a Gurley stiffness parameter) of the pleated media 10, and by suitably choosing the various geometric parameters (e.g. pleat height, pleat spacing, and so on) of the pleated media. Arrangements in which no pleat separators are present may be contrasted with, for example, the arrangements disclosed in U.S. Patent 4040804.

In other embodiments, pleat separators 61 (as shown in exemplary embodiment in Figs. 10 and 11) may be present, e.g. only in the inbound valleys, only in the outbound valleys, or in both. As evident in Figs. 10 and 11, a pleat separator 61 (of any type, composition or construction) will occupy only a portion of the valley in which it resides; in other words, a pleat separator will not occlude the pleat valley (in which case no airflow down the valley would be possible) but rather will allow airflow e.g. above and below the pleat separator, as indicated (by way of the open circles indicating inbound airflow) for the particular pleat separator marked 6G in Fig. 10. In some embodiments, the presence of such pleat separators, e.g. spaced down the pleat valley/flow channel as shown in Fig. 11, may actually disrupt the airflow (e.g. may cause turbulence or mixing) which may actually enhance the ability to transfer water out of or into the flowing air, and/or may enhance the ability to filter particles from the flowing air.

In some embodiments, at least some of the inbound and/or outbound pleat valleys may comprise pleat separators 61 in the form of parcels of hardened adhesive. The term “adhesive” is used broadly to signify any material that can be deposited, e.g. as a droplet or bead, onto a major surface of media 10 in a state (e.g., liquid, molten, softened, or semi-softened) in which it is sufficiently flowable or deformable that it can penetrate into pleat valleys (as the pleat valleys are formed during the pleating process) to satisfactorily form a pleat separator. Any suitable material may be used, including e.g. hot-melt adhesives, UV-cure adhesives, thermally-cured adhesives, moisture-cure adhesives, and so on. In some embodiments, the adhesive may be a hot-melt adhesive that is deposited through e.g. conventional hot-melt deposition methods (e.g. by use of a grid melter), after which the adhesive is cooled to harden. The adhesive is not required to necessarily exhibit any pressure-sensitive adhesive functionality after being hardened; in other words, the adhesive may be a non-tacky, e.g. hard material after being hardened.

In some embodiments, the adhesive may be deposited by passing the media underneath an adhesive-deposition nozzle or by moving the adhesive-deposition nozzle along the media. Typically, the operation of the adhesive-deposition nozzle may be intermittent (e.g. the deposition may be pulsed) so that parcels of adhesive are deposited at desired spacings along the longitudinal axis of the media, so as to correspond to the desired pleat spacing and pleat height. Multiple nozzles may be provided, e.g. spaced across the transverse width of the media at desired intervals.

In some embodiments the adhesive may be applied while the support media is held in a first, relatively open pleating pattern (that is, with a fairly large pleat spacing), with the pleated media then being compressed along its longitudinal axis to achieve the final (e.g. tighter) pleating pattern, after which the adhesive is then allowed to harden. In other embodiments, the media may not yet be pleated (but may have been scored to render it pleatable) when the adhesive is applied; in other words, the adhesive may be applied when the media is still in a flat, unpleated configuration. The media may then be compressed (with the adhesive still in an at least softened state) along the longitudinal direction of the media to a final pleated configuration. This can cause each adhesive parcel to fill a portion of the pleat valley. The adhesive may then be hardened while the support media is held in this pleated configuration. General methods of applying an adhesive to a pleated or pleatable media are disclosed e.g. in U.S. Patent 7896940, which is incorporated by reference in its entirety herein.

It will be appreciated that the use of adhesive parcels as pleat separators 61 can provide significant advantages in that each adhesive parcel may be bonded to both of the opposing pleat walls of the valley in which it resides. This enables the adhesive parcel to (in addition to acting as a spacer that prevents the opposing pleat walls from approaching each other) apply a restraining force that prevents the opposing pleat walls from separating from each other. Thus, such adhesive parcels can have an enhanced effect on pleat- stabilization. In fact, in some embodiments it may be possible to, for example, only include such pleat separators in inbound pleat valleys (or only in outbound pleat valleys) rather than having to include pleat separators in both inbound and outbound pleat valleys.

Such adhesive parcels may be applied in any desired pattern. For example, multiple parcels 61 may be spaced down the length of a particular pleat valley 32, as indicated in exemplary embodiment in Fig. 11. Any suitable spacing of parcels may be used. Parcels may be included in each inbound (and/or outbound) valley, as indicated in Fig. 10. Or, parcels may be alternatively placed in successive inbound and outbound valleys. Adhesive parcels may be applied simultaneously to the upstream and downstream major surfaces of the media; or, adhesive parcels may be applied to one major surface and then to the other major surface.

In a variation of the above approach, parcels of hardened adhesive may be used along one, or both, corrugated edges 15 and 16 of pleated support media 10 in a particular manner. In contrast to the use of such parcels as pleat separators (in which case the parcels only partially fill the pleat valley so that airflow is still allowed), an edge adhesive may be used to form “edge dams” that occlude corrugated edges 15 and 16. In such an approach, the parcels of adhesive are each configured to completely fill the valley (along the “depth” direction D of the pleated media) at the location along the valley at which the parcel is provided. Such edge dams may be provided in inbound valleys, in outbound valleys, or in both. Such an edge dam or dams may, for example, render it unnecessary to seal corrugated edges 15 and 16 of pleated media 10 with occlusive facings 75 and 76 of the type shown in Figs. 1 and 4. (Such edge dams may also render it unnecessary to e.g. dip edges 15 and 16 of pleated support media edge-wise into a potting material in the manner mentioned later herein.) In other words, such edge dams may serve as an occlusive seal that prevents airflow into (or out of) the pleat valleys at that edge of the pleated media. Such edge dams may be provided by e.g. depositing parcels of adhesive, or a continuous bead of adhesive extending along the longitudinal direction of the media, at a desired location closely proximate an edge 15 or 16 of support media 10, and then compressing the media to its final pleated configuration so that the adhesive completely fills the pleat valleys.

If desired, a sealant or potting material (e.g. a hardenable material such as an RTV silicone or the like) may be disposed along one or both corrugated edges 15 and 16 of pleated media 10 so that edges 15 and/or 16 are occluded edges. This may be done e.g. by dipping edges 15 and 16 edge-wise into a bead of the potting material. (Such a material is thus distinguished from an above-described adhesive edge dam that is applied to a major face of the pleated media.) The potting material, after hardening, may occlusively seal the corrugated edges of the pleated media. Such an approach may be used as an alternative to, or in addition to, the use of corrugated-edge occlusive facings 75 and 76, and/or the use of occlusive adhesive edge dams, that were described previously. However, in some embodiments, the use of occlusive facings and/or occlusive adhesive edge dams may eliminate the need for any such edge-sealing material. In at least some embodiments, pleated support media 10 does not comprise any type of pleat- stabilizing member (e.g., strips of chipboard, a layer of wire mesh, a nonwoven scrim, a set of filaments, etc.) that is bonded to pleat tips of a major side of the pleated support media to stabilize the pleat spacing. However, in some embodiments the inbound side and/or the outbound side of pleated media 10 may comprise at least one pleat-stabilizing member that extends at least generally along the longitudinal direction of the pleated media and that is bonded to multiple pleat tips. In some embodiments, such a pleat- stabilizing member or members may be at least substantially planar when viewed along the pleat direction. Pleat-stabilizing members that are bonded to pleat tips and that do not substantially enter, or reside in, the pleat valleys, are distinguished from the above-described pleat separators, e.g. in the form of adhesive parcels, that reside in the pleat valleys.

One such set of pleat stabilizing members are exemplified by filaments 65 as depicted in Fig. 12. Such filaments will collectively be substantially planar (linear in profile) when viewed along the pleat direction, as is evident from Fig. 12. In the particular arrangement in Fig. 12, the filaments are parallel to each other and extend substantially along the longitudinal axis of the pleated media. In some particular embodiments, any such filaments (or other pleat-stabilizing members) may be provided on the side of pleated support media 10 that is opposite permselective film 50. Thus for example, if film 50 is provided on the major outbound side 13 of media 10, filaments 65 may be provided on major inbound side 11 of media 10, as in the exemplary design of Fig. 12. Such filaments may be e.g. adhesively bonded or thermally bonded to the pleat tips. In particular embodiments, such filaments may be extruded onto the support media (while the support media is temporarily held, by any suitable pleating fixture, in the desired pleated configuration ) and bonded to the pleat tips, after which the pleated support media may be removed from the pleating fixture.

In some embodiments a facing 71 or 72 (as discussed earlier and as depicted e.g. in Fig. 4) may serve as a pleat-stabilizing member. That is, in some embodiments, a pleated support media may be completely formed (i.e. with the pleats in a stable condition), after which facings 71 and 72 may be applied thereto. In such instances, facings 71 and 72 may serve primarily to occlude the major sides of the pleated support media; they may not contribute significantly to the stabilizing of the pleats. However, in other instances, a facing 71 and/or 72 may help to stabilize the pleats. In particular embodiments, such a facing may be brought into contact with a pleated support media 10 while the media is temporarily held (e.g. by any suitable pleating fixture) in a desired pleated configuration. The facing(s) may be bonded to the pleat tips to stabilize the pleats in this configuration, after which the pleated support media may be removed from the pleating fixture.

Various aspects of producing an ERV core comprising a pleated seamless support media 10 bearing a permselective film will now be discussed. In general, the permselective film 50 can be laminated to support media 10 (e.g. with media 10 in a flat, as yet unpleated condition), by any suitable method. Such methods might include e.g. the use of a hot melt spray adhesive, a hot melt nonwoven adhesive, or by thermal lamination. After the lamination, the support media 10 bearing permselective film 50 thereon, can be co-pleated.

In order to achieve the highest possible transport of water vapor through permselective film 50, it may be desirable that film 50 be as thin as possible. Thus in various embodiments, film 50 may be e.g. 15, 12, 10, 8, 7, 6 or 5 microns in thickness. Some such films may be difficult to handle by conventional web handling methods and in particular may be difficult to laminate to a support media 10 (e.g. a fibrous web) that has a nonuniform major surface. The present investigations have indicated that it can be helpful to provide permselective film 50 with one or more sacrificial liners that enable the film to be easily handled. Thus for example, a permselective film 50 may be made e.g. by multilayer extrusion (e.g. by multilayer film-blowing methods) along with first and second outer liners between which permselective film 50 is sandwiched. One such liner (which may be, for example, a polyolefin such as LDPE) can then be removed to expose one major surface of the permselective film 50. This major surface of film 50 can then be laminated (e.g. by any of the above methods) to a major surface of support media 10. After the lamination is complete, the other liner can then be removed, thus leaving permselective film 50 behind on the major surface of the support media. The support media 10 and permselective film 50 can then be co-pleated.

Support media 10 can be pleated by any suitable method that can provide a desired pleat spacing. In some embodiments media 10 may be scored to provide score lines, along which the media can be folded to form very sharp pleat tips with a small radius of curvature. In some embodiments, the scoring may be done prior to the lamination of film 50 onto media 10; also, the scoring may be applied to the side of media 10 opposite that to which film 50 is to be laminated, e.g. to preserve the smoothest possible surface for film 50 to be laminated to.

The actual pleating of media 10 should be done in such manner as to avoid damage to permselective film 50. It is noted that some water-vapor-permselective films (e.g. many PEBAX films) are rather stretchy and thus may be able to survive sharp bending at the pleat tips, without undue damage. Furthermore, since in many cases the pleat tips may endup in contact with an occlusive facing (e.g. facing 71 or 72 as described earlier) even if some damage to the permselective film may be present at the pleat tips, this may be inconsequential since little or no actual transfer of water vapor may occur at such locations.

The actual pleating (whether or not the media has been scored) may be performed using any suitable pleating method and/or apparatus. Such methods may rely on, for example, the use of a system of flites, cleats, or paddles, and/or a helical screw conveyor. Various such approaches are described e.g. in U.S. Patents 4976677, 5389175, 7896940, and 9808753. Often, a pleatable media may be pleated so that the Pleat Direction follows the cross-web (transverse) direction of the media, with the longitudinal axis of the pleated media following the machine direction of the media.

In some embodiments, support media 10 (bearing film 50) may be formed over a pleating fixture that allows the media to be shaped into the desired pleated shape. The support media may be held on the pleating fixture at whatever conditions are needed in order to impart the media with a long-lasting pleated configuration. (In some embodiments such a pleating fixture may find further use, e.g. as an air-entry manifold, in the finished ERV core, as discussed later.) As noted earlier herein, in some embodiments the pleated media (bearing film 50) may be temporarily held in a pleated configuration and a facing (e.g. 71 or 72) applied to a major side thereof and bonded to the pleat tips thereof; in such a case the facing may serve to maintain the pleat spacing as well as an occlusive seal.

Once support media 10 and permselective film 50 have been co-pleated, further processing may be performed as desired in order to maintain the desired pleat configuration, to apply various facings, covers, wraps, and so on, to the major faces and/or the various edges of the pleated support media, to form the completed ERV core.

Discussions up till now have primarily concerned ERV cores that are configured in a side-fed arrangement, e.g. as shown in Fig. 1. However, it is also possible to configure a pleated support media 10 (bearing a permselective film 50) to provide an ERV core in an edge-fed configuration, as indicated in Fig. 13. That is, in a side-fed arrangement, air (for example, inbound air IEN) enters the pleat valleys through an opening (e.g., entrance 2) provided in a major side of the core, as shown in Fig. 1. In an edge-fed configuration, the air enters the pleat valleys edge-wise (along the Pleat Direction) through openings in a corrugated edge ofthe pleated support media. For instance, in Fig. 13, exemplary edge-fed core 1 comprises an inbound air entrance 6 and an inbound air exit 7; and, an outbound air entrance 8 (through which outbound entering air OEN enters the core) and an outbound air exit 9 (through which outbound exiting air OEX leaves the core).

In such embodiments, an air entry manifold 90 may be provided to facilitate the distribution of the air into the various openings. Thus in Fig. 9 an entry manifold 90 for outbound air is depicted (a similar entry manifold for inbound air may be present proximate opposing corrugated edge 15, but is not shown in Fig. 9). Entry manifold 90 comprises multiple air-delivery nozzles 91 that protrude transversely inward from the main body of manifold 90 and that are specifically shaped to fit within the various openings of the outbound air pleat valleys/flow channels 22. When manifold 90 is in place, these shaped portions (nozzles) 91 of air entry manifold 90 extend transversely into the various openings of the outbound air pleat valleys/flow channels 22.

It will be appreciated that in such an edge-feed configuration, facings 71 and 72 may cover the entirety of the major sides of pleated media 10, since there is no need to provide side-entry openings.

In some particular embodiments, an outbound air entry manifold and/or an inbound air entry manifold, e.g. of the general type depicted in Fig. 9, may be used in the pleating process and incorporated into the pleated support media at that point (rather than, for example, being fitted to the finished ERV core) . Specifically, such a manifold may be used as a pleating fixture, with support media 10 being conformed to the shaped portions 91 ofthe manifold 90) in order to form media 10 into a pleated structure. The pleating fixture 90 may then remain with the finished ERV core to serve as an air entry manifold.

Discussions heretofore have concerned arrangements in which air that is side-fed, is similarly side- exited (as in Fig. 1); and, in which air that is edge-fed, is similarly edge-exited (as in Fig. 13). It will be appreciated that hybrid approaches are possible e.g. in which air is side-fed but is edge-exited, or vice versa. In some embodiments an ERV core of the general type disclosed herein may be formed into a cylindrical shape, e.g. that resembles items often referred to as cartridge filters.

An ERV core as disclosed herein may be e.g. mounted into any suitable holder, enclosure, or the like, in order to perform the functions desired. For example, the ERV core may be installed into an enclosure that is plumbed to bring inbound and outbound air to the respective entrances of the core, and to remove inbound and outbound air that exits the core. (In some cases the ERV core itself may be supplied with a manifold to enable such arrangements.) Such an enclosure may be made of e.g. sheet metal, molded plastic, or any combination thereof. One or more resilient gaskets, seals or the like may be provided to securely hold the ERV core in the enclosure. In many embodiments, such a holder or enclosure may be part of an air-exchange system comprising one or more powered fans that motivate the inbound and/or outbound air to move through the ERV core.

In some instances, an ERV core as disclosed herein may be configured for long-term, e.g. semi permanent, use. In some embodiments, such a core may be configured so that it can be removed from the holder and cleaned (e.g. by vacuuming, washing, etc.). In some embodiments, an ERV core may be configured to be replaced after a suitable time (e.g., 3 months, 6 months, or one year).

In some embodiments, a support media 10 that is configured to perform particle filtration, may only perform particle filtration. However, in other embodiments, one or more layers of the media may contain one or more materials that at least partially remove one or more components (e.g., gases, vapors, odors, and so on) from the moving airstream. The components in the fluid may be e.g. sorbed onto or into an active sorbent, may be reacted with a reactive ingredient, may be exposed to a catalyst, and so on. Potentially suitable materials for such uses include e.g., activated carbon and surface-treated activated carbon; alumina and other metal oxides; sodium bicarbonate; metal particles (e.g., silver particles) that can remove a component from a fluid by adsorption, chemical reaction, or amalgamation; catalytic agents such as hopcalite and/or gold (which can catalyze the oxidation of carbon monoxide); clay and other minerals treated with acidic solutions such as acetic acid or alkaline solutions such as aqueous sodium hydroxide; ion exchange resins; molecular sieves and other zeolites; silica; biocides; fungicides and virucides. Mixtures of any such materials can be employed.

It will be appreciated that in many embodiments, the filtration of particles (and optionally, of any other gaseous or vaporous component) will be applied to the inbound air (that is, air from an external environment that is being exchanged into a building). However, in some embodiments, if desired for some particular reason, outbound air (that is being exhausted from a building) may be filtered in any such manner, whether instead of, or in addition to, the inbound air.

In still further embodiments a permselective film 50 may be sandwiched between layers of fibrous material. For example, a film 50 may be laminated to a layer of support material, after which a layer of particle-filtration fibers (e.g. electret fibers) can be deposited atop the permselective film 50. Such a design may be used in combination with any of the arrangements and methods disclosed herein. An ERV core as described herein may find use in any instance in which it is desired to exchange thermal energy (sensible heat) and water vapor (latent heat) between two streams of moving air. As noted, in many embodiments this may occur in the guise of an air-exchanging system for a building (e.g. a dwelling, light industrial building, office building, retail building, and so on) or a particular unit or portion of a building. However, such a core may be used in any suitable circumstance or application, for example to extract thermal energy and water vapor from a combustion-gas exhaust stream (of, e.g. a furnace, boiler, water heater, or most any engine or apparatus that generates hot and water- vapor-rich exhaust gases). The core may transfer the extracted thermal energy and water vapor to, for example, feed air that supplies the combustion apparatus. Such uses are not limited to e.g. internal combustion engines but might also include e.g. fuel cells and the like. Such an ERV core might also be used in non-building environments in which it is desired to introduce (and optically, to filter) outside air into an enclosed space. Thus, for example, such a core might be used in an air-exchange/filtration apparatus for a cabin of a motor vehicle (e.g. an automobile, aircraft, etc.).

Test Procedures

Guriev Stiffness

Gurley Stiffness is measured using a Gurley Stiffness Tester Model 417 IE (Digital), available from Gurley Precision Instruments, Troy, NY. The Stiffness is measured according to the procedures provided in the operating manual for the Tester. The Tester is calibrated with a standard brass shim prior to sample testing. For each material, three separate individual physical samples are tested. Each sample is a flat-web (unpleated) sample, cut (e.g. from roll) to a total length of 3.5 inches, corresponding to a test dimension of 3 inch length (with 0.25 inches of the sample being held in the upper clamp of the Tester and with 0.25 inches of the sample extending below the lower pendulum of the Tester). Sample width is 1 inch. If the sample exhibits an identifiable machine direction (downweb direction), the sample is cut so that the long (test) dimension is aligned with the machine direction of the sample. Samples comprising organic polymeric webs (e.g. nonwoven webs) are treated with a static discharge gun prior to testing. Each individual physical sample is tested two times, cycling back and forth from the left and right side of the sample. Results are averaged and are reported in milligrams of force (Gurley Units).

Percent Removal Percent Penetration Pressure Drop

Percent Removal, Percent Penetration, Pressure Drop, and related parameters are obtained using a challenge aerosol containing either DOP (dioctyl phthalate) liquid droplets or NaCl (sodium chloride) solid particulates, in generally similar manner as disclosed in PCT International Publication No. WO 2015/199972 and in U.S. Provisional Patent Application No. 62/015637, both of which are incorporated by reference herein. An Automated Filter Tester AFT Model 8130 (TSI, Inc., St. Paul MN) may be used, with a challenge aerosol that comprises DOP droplets or NaCl particulates, with a mass median diameter in the range of approximately 0.3 pm (e.g., a mass median diameter of approximately 0.26 for DOP, and a mass median diameter of approximately 0.33 for NaCl). The challenge aerosol may be delivered to provide a face velocity of 14 cm/s. In order to evaluate performance in channel-filtration, the test procedures and apparatus may be modified (from those described in the above-cited documents) to feed the airstream/challenge aerosol through a set of flow channels (rather than through a filtration web as with conventional through-filtration) of a sample pleated filter/support media of an ERV core, with the particle concentration being measured at the sample inlet and outlet. The Percent Removal of particles can thus be obtained (collectively, for the entire set of flow channels of the sample). The Percent Penetration is 100 minus the Percent Removal. The Pressure Drop through the flow channels can also be monitored, e.g. by way of transducers e.g. of the general type available from MKS Instruments (Andover, MA).

It will be apparent to those skilled in the art that the specific exemplary elements, structures, features, details, configurations, etc., that are disclosed herein can be modified and/or combined in numerous embodiments. All such variations and combinations are contemplated by the inventor as being within the bounds of the conceived invention, not merely those representative designs that were chosen to serve as exemplary illustrations. Thus, the scope of the present invention should not be limited to the specific illustrative structures described herein, but rather extends at least to the structures described by the language of the claims, and the equivalents of those structures. Any of the elements that are positively recited in this specification as alternatives may be explicitly included in the claims or excluded from the claims, in any combination as desired. Any of the elements or combinations of elements that are recited in this specification in open-ended language (e.g., comprise and derivatives thereof), are considered to additionally be recited in closed-ended language (e.g., consist and derivatives thereof) and in partially closed-ended language (e.g., consist essentially, and derivatives thereof). Although various theories and possible mechanisms may have been discussed herein, in no event should such discussions serve to limit the claimable subject matter. To the extent that there is any conflict or discrepancy between this specification as written and the disclosure in any document mentioned and/or incorporated by reference herein, this specification as written will control.