EA039572B1 - Method for producing an enthalpy exchanger and enthalpy exchanger - Google Patents

Abstract

The invention provides enthalpy exchanger elements (E, E') and enthalpy exchangers comprising such elements. Furthermore, the invention discloses a method for producing such enthalpy exchanger elements and enthalpy exchangers, comprising the steps of a) providing an air-permeable sheet element (1); b) laminating at least one side (1a, 1b) of the sheet element (1) with a thin polymer film (3, 4) with water vapor transmission characteristics; and c) forming the laminated sheet element (1) into a desired shape exhibiting a three-dimensional corrugation pattern (5, 5, ...).

Description

The invention relates to elements of an enthalpy exchanger and enthalpy exchangers containing such elements. In addition, the present invention proposes a method for obtaining these elements of the enthalpy exchanger and enthalpy exchangers.

It is well known to use various types of heat exchangers for various purposes. Typically, heat exchangers are used to extract thermal energy from one liquid or fluid to another. This kind of thermal energy is called sensible energy. Thermal energy or sensible energy from one fluid, typically air, is extracted into another fluid that flows adjacent to the first fluid, such as in parallel, counter or cross flow, with the second fluid at a lower temperature. By inverting the fluid streams, the exchange between the two streams will create a colder fluid. Heat exchangers used to recover sensible energy are usually made of metal or polymer elements. There are different types as there may be cross flow, parallel flow or counter flow configurations. These elements delimit the flow channels between them in such a way that fluids can flow between them. Such devices are used, for example, in residential and commercial ventilation (HRV).

Another type of energy exchanger refers to the so-called latent energy, which includes the moisture contained in the air. It is known that metal or polymeric substances coated with a desiccant or membranes made of cellulose or a polymer impregnated with a desiccant are used for the exchange of latent energy. Between the plates made of cellulose or polymer, air channels are installed or created to allow the passage of fluids along the surface of the plates, thereby ensuring the transfer of moisture from one fluid to another. Since membranes generally lack structural strength, it is known that they can be combined with scaffolds or grids, which thereby limit the distances between the membranes.

In the case of a combination of the processes described above, i.e. heat exchange and moisture exchange, energy exchangers are called enthalpy exchangers. Such enthalpy exchangers ensure the exchange of sensible and latent energy, which leads to the recovery of total energy.

Membrane materials currently available are supplied in roll form. The membrane material is the most important part of the enthalpy exchanger. The membrane must be fixed and sealed in the form of a lattice or frame and located in such a way as to allow the passage of fluid between each layer of the membrane. Thus, it is clear that prior art enthalpy exchangers represent a compromise solution. They will generally lose in terms of sensible energy exchange to improve latent energy exchange due to the selective scope and characteristics of the membranes currently used.

Such an enthalpy exchanger constructed from suitable elements is described, for example, in WO 02/072242 A1. Corresponding membranes made of fibers are installed on the gratings. Lattices containing a membrane or spacers between adjacent membranes, i.e. separators and membranes in an alternating sequence, connected by brackets or stacked, as a result of which the direction of the plates is changed to create different directions of air flow.

In view of this prior art, the object of the present invention is to provide elements of an enthalpy exchanger and enthalpy exchangers, as well as a method for their production, providing the creation of enthalpy exchangers, while the efficiency of both the exchange of sensible energy and the exchange of latent energy in each element of the enthalpy exchanger increases, and the cost the production of enthalpy exchanger elements and enthalpy exchangers consisting of such elements is decreasing.

Another object of the present invention is to provide elements of an enthalpy exchanger and enthalpy exchangers with a high specific exchange surface in the case of steam, as well as a method for their production.

To achieve this goal, the present invention proposes a method for obtaining elements of an enthalpy exchanger, including the steps:

a) providing a breathable sheet component;

b) laminating at least one side of said sheet component with a thin polymeric film with water vapor permeability properties; and

c) shaping the laminated sheet component into a desired shape having a three-dimensional corrugated pattern.

The result is an enthalpy exchanger element that provides both the transfer of heat and water molecules in the form of vapor through the specified element from one side to the other side almost over the entire surface area of the element, which now has a higher specific exchange surface than the same elements on prior art. In contrast, molecules larger or less polar than water molecules, such as carbon dioxide and odor-related molecules, are prevented from passing through said element. In addition, the sheet component and the water vapor selective barrier material laminated to at least one side of the sheet component are molded into the desired corrugation.

- 1 039572 forms, using only one stage of molding (single-stage molding). Thus, on the one hand, the total (ie, sensible plus latent) energy transfer efficiency in the enthalpy exchanger element according to the present invention is increased, while, on the other hand, the production cost of such an element is reduced.

Alternatively, the sequence of steps b) and c) can be reversed in said process, i.e. molding the (not yet laminated) sheet component into a desired shape having a three-dimensional corrugated pattern, and then laminating at least one side of the molded sheet component with a thin water vapor permeable polymer film (two-stage molding).

Water vapor permeability means a water vapor permeation rate of at least 500 g/m ² /24 h, preferably at least 1000 g/m ² /24 h, even more preferably at least 1500 g/m ² /24 h and most preferably at least 2000 g/m ² /24 h as measured using the vertical cup method according to modified ASTM E 96-66 B; modifications: T _water = 30°C, T _air = 21°C, rel. humidity = 60%, air flow = 2 m/s.

Step c) of forming the laminated sheet component into the desired shape having a three-dimensional corrugated pattern may include a first step c1) and a second step c2).

Step c1) involves obtaining a first corrugated pattern or a reinforcing corrugated pattern with corrugations extending in the first direction and having a relatively fine structure. The first corrugated relief may have a sinusoidal, rectangular or triangular periodic profile. Such a first periodic profile of the first corrugated pattern preferably has a period of 0.5 to 2 mm and an amplitude of 0.5 to 1 mm. The first corrugated pattern may include adjacent ridges. There may be a certain distance between adjacent ridges, i.e. the space of the laminated or not yet laminated sheet component between adjacent ridges is a substantially flat area, where adjacent ridges may protrude in the same or opposite directions with respect to the sheet component. The height or depth, as well as the width of these separately located ridges, can be from 0.2 to 1 mm. The distance between the ridges can be 1 to 10 times greater than the width of the ridge. This optional first step c1) contributes to the overall rigidity of the enthalpy exchanger element.

Step c2) includes obtaining a second corrugated pattern or main corrugated pattern with corrugations extending in the second direction and having a relatively large structure that limits the geometrical dimensions of the cross section of the channel of the heat exchanger plate. Again, the second corrugated pattern may have a sinusoidal, rectangular or triangular periodic profile, but with larger dimensions than the first corrugated pattern. Such a second periodic profile of the second corrugated pattern preferably has a period of 2 to 10 mm and an amplitude of 2 to 10 mm. As a result, the optional first step c1) and the required second step c2) provide an enthalpy exchanger element with double corrugation and increased rigidity.

The first direction, i.e. the direction of the ridges of the first corrugated pattern forms an angle with respect to the second direction, i.e. the direction of the ridges of the second corrugated relief, while the specified angle is preferably from 45 to 90°, more preferably from 85 to 90° and most preferably about 90°.

The sheet material of the sheet component may comprise a polymer, preferably a thermoplastic polymer. The sheet component is therefore amenable to, for example, heat treatment in the molding step c). As thermoplastic polymer, polystyrene (PS), polyvinyl chloride (PVC), viscose or polyester such as polyethylene terephthalate (PET) or copolyester are preferably selected. The polymer of the sheet material preferably does not contain any plasticizer. The polymer of the sheet material may contain a biocide (bactericide and/or fungicide).

In a preferred embodiment, the sheet component is a web, preferably a nonwoven web. The web may contain only thermoplastic fibers, or a combination of thermoplastic fibers and thermoset fibers, or a combination of thermoplastic fibers and resin, or a combination of thermoplastic fibers and inorganic fibers. Most preferably, the web contains multicomponent or bicomponent fibers along with standard thermoset and/or thermoplastic fibers. Said web preferably contains more than 50% by weight of multicomponent or bicomponent fibers and may contain only multicomponent or bicomponent fibers. In addition, the fabric may contain metal fibers and/or wick fibers, providing high thermal conductivity together with mechanical strength and high capillary action (moisture conductivity), respectively. The inorganic fibers may be glass fibers, silicon carbide fibers or any mineral fibers.

Alternatively, the sheet component is a woven web, preferably having an anisotropic structure and resulting anisotropic properties. For example, the woven web may comprise thicker polymer fibers in the first fiber direction and thinner polymer fibers in the second fiber direction. The second direction of the fibers may be from 90 to 100°, preferably about 90°, relative to the first direction of the fibers. Because of the thicker polymeric fibers in the first fiber direction, an anisotropic woven fabric can withstand more stretch along the first fiber direction without being mechanically weakened (or even damaged) than along the second fiber direction with thinner polymer fibers.

Alternatively, the sheet component may comprise a nonwoven web which may have an anisotropic structure and resulting anisotropic properties, and a woven web preferably having an anisotropic structure and resulting anisotropic properties.

The sheet component may contain additional reinforcing fibers to provide additional strength. Such reinforcing fibers may be at least fibers selected from metal fibers, carbon fibers or thermoplastic polymer fibers. The reinforcing fibers may extend within the sheet component in a first general direction. The reinforcing fibers are preferably non-straight. In particular, they may have an undulating pattern, for example a triangular or sinusoidal flat pattern, preferably with a period of 1 to 3 mm and an amplitude of 1 to 3 mm. Alternatively, they may be of a swirling shape, for example a helical shape, preferably with a helix diameter of less than 1 mm.

The reinforcing fibers may be continuous fibers or staple fibers with a minimum length of 5 mm. The metal fibers can be selected from aluminum, copper, silver or steel fibers with a diameter of 10 to 200 µm, preferably 20 to 100 µm.

The first common direction of the undulating pattern and/or the twisting shape of the reinforcing fibers preferably forms an angle with respect to the direction of the second corrugated pattern that defines the geometrical dimensions of the cross section of the channel of the heat exchanger plate. These directions preferably form with respect to each other an angle of from 45 to 90°, more preferably from 85 to 90° and most preferably about 90°.

During step c) or in particular during steps c1) and c2), but especially during step c2), the indirect reinforcing fibers are straightened. In particular, the undulating relief and/or the swirling shape is stretched and thus smoothed out in the profile, i.e. the amplitude of the undulating relief decreases and its period increases and/or the diameter of the swirling/helical shape decreases and its period (or pitch) increases. Once the indirect carbon and/or metal fibers are fully straightened, the sheet component will no longer be able to stretch along the first general direction.

In addition, when the sheet component is heated above the softening temperature of the thermoplastic polymer fibers before or during step c) or, in particular, before or during steps c1) and/or c2), the thermoplastic fibers will deform under local tension and/or bending. After the shaping step c) or the shaping steps c1) and c2), the permanent deformation of the thermoplastic polymer fibers will contribute to the dimensional stability, i.e. preservation of the form, an element of the enthalpy exchanger.

Preferably, if carbon fibers are included in the sheet component, they extend along the second direction of the second (main) corrugated pattern. Thus, during the molding step c) or during the molding sub-step c2), the carbon fibers will not undergo any bending. However, these fibers contribute to the overall strength of the sheet component before and after molding step c) or c2).

Preferably, if metal fibers are included in the sheet component, they may extend along any direction within the sheet component. Thus, during the molding step c) or during the molding sub-step c2) the metal fibers will undergo bending under metal cold working conditions even if the sheet component is heated above the softening temperature of the thermoplastic polymer fibers. After the shaping step c) or the shaping steps c1) and c2), the permanent deformation of the metal fibers will contribute to the dimensional stability, i.e. preservation of the form, an element of the enthalpy exchanger.

The web fibers preferably have diameters of 1 to 40 µm, more preferably 3 µm to 40 µm, and most preferably 5 to 20 µm. As a result, when laminating a web with a thin polymer film with water vapor permeability properties in lamination step b), the fibers of the web in direct contact with the thin polymer film will only cover a small portion of the surface of the thin polymer film, thus minimizing any blockage of the thin polymer film. polymer film. In addition, even if they do not permanently deform, as described above for thermoplastic polymer fibers or metal fibers, any web fibers subjected to elastic bending during step c) will have a high degree of flexibility, facilitating step c) of molding.

Fibers or filaments of a web within a sheet component, and in particular fibers and filaments on nets

- 3 039572 surface of the sheet component, may preferably have linear mass densities (filament weights) from 1 to 10 dtex (1 tex = 1 g/1000 m; 1 dtex = 1 g/10000 m). Such thin fibers have a strong capillary effect, which allows them to quickly transfer moisture. In addition, when applied to the surface of the sheet or both surfaces of the sheet, they provide a smoother and less abrasive surface. First, it helps reduce the risk of damage to the very thin adjacent functional membrane layer laminated to the appropriate surface. Secondly, it helps prevent any near-surface air from forming on the non-laminated surface of the sheet.

The web fibers may have substantially circular, triangular, or oval cross sections. In addition, the web fibers may have X-shaped or star-shaped cross sections. The web may contain fibers with different cross sections, preferably selected from the types of cross sections mentioned.

In addition, to improve structural stability after the forming step, the web may contain a surface impregnation composition, preferably a thermoplastic or thermoset polymer. In addition or alternatively, the web may comprise a surface impregnation compound which can be cross-linked after molding step c), preferably a resin which can be cured by UV irradiation after molding step c).

The web or element of the enthalpy exchanger may contain a hydrophobically treated layer on one of its sides and a thin polymer film on the other side, i.e. there is a single water-repellent impregnation.

This can be done in step b) by laminating only one side of the web with a thin polymer film with water vapor permeability properties and allowing the other side of the web to be hydrophobized before, during or after said lamination step b). Such hydrophobization can be performed even after molding step c).

The hydrophobization of the web is preferably carried out before step b) of lamination, i. e. before, during or after step a). This prevents accidental hydrophobicization of the web-facing surface of the thin polymeric film with water vapor permeability properties.

The web or element of the enthalpy exchanger may comprise a hydrophobically treated layer on both of its sides and inside a thin polymer film extending between said sides and parallel to the first hydrophobically treated layer and the second hydrophobically treated layer of the web or element of the enthalpy exchanger, i.e. There is a double water-repellent impregnation.

This can be achieved through the following steps.

First, hydrophobizing one side of the first web or the entire first web before, during or after any step b) of lamination.

Secondly, carrying out hydrophobization of one side of the second web or the entire second web before, during or after any stage b) of lamination.

Third, laminating one side of the first web with the first side of a thin polymer film with water vapor permeability properties.

Fourthly, laminating one side of the second web with the second side of a thin polymer film with water vapor permeability properties to obtain a three-layer structure containing a thin polymer film located between the first web and the second web.

Finally, according to step c), such a laminated sheet component having a first web/thin film/second web type three-layer structure is formed into a desired shape having a three-dimensional corrugated pattern.

Steps three and four are preferably performed simultaneously, ie. by joint lamination or one-stage lamination of the first web and the second web with one thin polymer film with water vapor permeability properties to obtain a three-layer structure with a thin polymer film located between two sheets of the web.

The hydrophobization of the first web and/or the second web is preferably carried out before any laminating step b) i. e. before, during or after step a) of providing the web. Again, this prevents inadvertently hydrophobicizing the surface of any thin polymeric film with water vapor permeability properties facing the web, i.e. first canvas or second canvas.

Instead, the hydrophobization of the first web and/or the second web can be carried out after the molding step c).

The sheet component may consist of a single web layer containing any of the fiber combinations described in the previous paragraph. Alternatively, the sheet component may consist of several, preferably two or three, stacked layers of web attached to each other, with each layer containing a different fiber selected from the fiber combinations described in the previous paragraph.

Several folded layers of fabric may have different thread weights. These layers may be

- 4 039572 the first layer containing relatively thin threads, for example, from 1 to 10 decitex, and the second layer containing relatively large threads, for example, from 10 to 40 decitex.

The second layer with larger or heavier filaments is preferably attached to the thin polymer film (membrane), which provides a small area of direct contact between the surface of the sheet component and the thin polymer film attached thereto, and thus increases the active membrane surface area of the thin polymer film. At least a portion of the heavier filaments are preferably bicomponent fibers which allow the thin polymer film to be attached to the surface of the sheet component with less or no adhesive.

Alternatively, depending on the type of filaments, it may be preferable if the first layer with thinner filaments is brought into contact with or attached to a thin polymer film (membrane), which provides a smooth surface at the sheet component/thin polymer film interface that does not damage the polymer film during molding step c) in forming the corrugated pattern or during molding sub-step c2) in forming the second corrugated pattern or during the final application.

Regardless of its position within the sheet component, a second layer with heavier or thicker yarns will provide an open and highly breathable layer of the sheet component.

In addition, the sheet component may contain fine filaments or fibers with strong capillary properties to enhance the transfer of moisture through the sheet component. When measured according to DIN 53924, fine filaments or fibers preferably exhibit a height increase of at least 30 to 60 mm after 30 s and more preferably a height increase of at least 40 to 60 mm after 30 s.

If the forming in step c) or step c2) is carried out by vacuum forming by the forces of the upper corrugating tool, the sheet component may have an asymmetric structure throughout its thickness. In particular, it may comprise a layer with relatively thin filaments on the side exposed to vacuum, which provides good reproduction of the geometric dimensions of the mold, and relatively large filaments facing the upper crimping tool, which provides the sheet component with the required structural strength.

The sheet component may comprise a nonwoven fabric layer and a woven fabric layer attached to each other. The woven fabric preferably has an anisotropic structure and resulting anisotropic mechanical properties as described above.

A portion of the fibers within the sheet component, preferably 5 to 60% by weight, may be hollow fibers. A portion of the fibers within the sheet component, preferably 20 to 70% by weight, may be bicomponent fibers. The cross sections of such bicomponent fibers may have a circular and/or non-circular cross section.

A portion of the fibers within the sheet component, preferably 5 to 60% by weight, may be hydrophilic fibers exhibiting strong capillary properties that enhance moisture transfer. The surface of such capillary fibers is preferably hydrophilic and their core is hydrophobic.

A portion of the fibers within the sheet component, preferably 5 to 30% by weight, may be water-absorbing fibers, preferably hydropolymers, providing an aqueous buffer in case of excess moisture.

The sheet component may have a textured surface and/or an embedded mesh structure. As a result, this type of sheet component will cover the minimum surface area of the adjacent thin polymer film attached to the sheet component. Such an embedded mesh structure may be the first described above or the reinforcing corrugated pattern obtained in the first molding step c1).

In addition to, or as an alternative to, the measures described above to increase the structural strength of the sheet component prior to subsequent lamination, a sheet component that has not yet been laminated can be treated with

1) hydrocoupling and/or hydroplexing; and/or

2) surface texturing; and/or

3) combining a mesh structure with a relief adapted to the geometric dimensions of the second or main corrugated relief.

In addition to or as an alternative to the above measures to increase the structural strength and formability of the sheet component, said sheet component can be made with an anisotropic distribution of fibers, which provides higher overall strength of the sheet component and/or higher strength of the sheet component in a preferred direction. In particular, as mentioned above, the distribution of anisotropic fibers can be provided with at least a fiber selected from carbon fibers, metal fibers, or thermoplastic polymer fibers included in at least one of several layers of the sheet component.

The metal fibers and/or thermoplastic polymer fibers are preferably arranged in a nearly orthogonal orientation with respect to the second direction of the second (main) corrugated pattern, or said fibers may extend along any direction within the sheet component. The carbon fibers are preferably oriented parallel to the second direction of the second (main) corrugated pattern.

Stage b) lamination may include bonding, preferably thermal bonding, sealing and/or gluing a thin polymer film with a sheet component. A thermoplastic adhesive (hot melt adhesive), a hot-melt adhesive or a UV-curable adhesive is preferably used to form a bond between the resin film and the sheet component.

According to a preferred embodiment, the polymer thin film is a monolithic membrane, i. e. a non-porous membrane exhibiting, in the case of individual water molecules, the mechanism of dissolution-diffusion transfer. The maximum stretch of such a monolithic membrane is preferably 100 to 300%, more preferably 150 to 200%.

According to a further preferred embodiment, the polymer thin film is a multilayer film containing a sequence of polymer layers made from different types of polymers. Thus, using several given types of polymers, it is possible to design and manufacture thin polymer films with different water vapor permeability properties.

The type of polymer for making each polymer layer is preferably selected from the group consisting of polyester-ether copolymer, polyesteramide and polyesterurethane.

The total thickness of the thin polymeric multilayer film is preferably 5 to 200 µm, more preferably 10 to 150 µm.

The thickness of each individual polymeric layer within the thin polymeric multilayer film may be from 1 to 20 µm, preferably from 4 to 20 µm, and most preferably from 4 to 15 µm.

In general, the polymer film(s) or polymer layer(s) should be as thin as possible to ensure high transfer rates. In the arrangement of the enthalpy exchanger element of the present invention, the water vapor transfer boundary layer is a three-dimensional sheet component adjacent to or between two polymer laminates. To ensure the mechanical strength and reliability of the laminate(s) on the one hand and high transfer rates on the other hand, a layout with a polymer film (laminate) thickness of 1 to 20 µm, preferably 4 to 20 µm and most preferably 4 to 15 µm is chosen. . Thus, the three-dimensional sheet component is as thin as possible and as permeable as possible. The sheet component is preferably a web with a thickness of 200 to 600 µm, preferably 300 to 500 µm. The sheet component is preferably a web with a fiber volume fraction of 10 to 65% by web volume, preferably 20 to 50% by web volume.

The thermoplastic polymer(s) of the thin polymer film preferably does not contain any plasticizer. Instead, the thin polymer film may contain a biocide (bactericide and/or fungicide). Such a biocide will inhibit the growth of bacteria and fungi on the polymer and thus provide longer periods of operation without cleaning.

As mentioned above with respect to a thermoplastic polymer, the molding step c) may be a shirring step or a thermoforming step, preferably a vacuum forming step. The thermoforming step provides at least a first mold section (eg, bottom tool) comprising first corrugated structures co-defining a predetermined corrugated pattern of the enthalpy exchanger element to be manufactured. Along with at least the first mold section, a second mold section (e.g., top tool) is provided at the thermoforming stage, containing second corrugated structures in addition to the first corrugated structures and/or forming vacuum, jointly limiting the predetermined corrugated pattern of the enthalpy exchanger element to be manufactured.

Prior to the actual molding operation of the laminated sheet component at a certain predetermined molding temperature of the first mold section or at certain predetermined molding temperatures of the first and second mold sections, the laminated sheet component is preferably preheated to a preheating temperature that is several degrees lower than the temperature molding. When shirring, the preheating temperature can be lower.

The molding temperature is preferably provided by internally heated first and/or second mold sections.

The preheat temperature is preferably provided by exposing the as yet unformed laminated sheet to electromagnetic radiation (eg at infrared or microwave frequencies) and/or mechanical waves (eg at ultrasonic frequencies).

The present invention also provides an enthalpy exchange element, preferably obtained using the method described in the previous paragraphs, including a sheet component and a predetermined corrugated pattern, wherein the first thin polymer film is laminated to the first side of the sheet component and/or the second thin polymer film laminated on the second side of the sheet component, and both thin polymer films have the properties of water vapor permeability.

The first thin resin film and the second thin resin film may be identical to each other. By laminating both sides of the sheet component, an enthalpy exchanger element with excellent hygienic properties is obtained. By laminating only one side of the sheet component, the thermoplastic polymer of the sheet material is preferably hydrophobized and/or contains a biocide (bactericide and/or fungicide), again providing an enthalpy exchange element with excellent hygiene properties.

The first thin resin film and the second thin resin film may be different from each other. This provides additional freedom to adjust and optimize the heat and moisture transfer characteristics of the enthalpy exchanger element.

Finally, the present invention provides an enthalpy exchanger comprising at least three sheet-like or plate-like enthalpy exchanger elements as described in any of the preceding paragraphs, which are stacked and attached to each other by their respective corrugated patterns in a parallel orientation to form parallel flow passages. that allow fluids to flow through them. The individual elements of the enthalpy exchanger can be attached to each other and sealed by welding, preferably using laser welding, and/or gluing, preferably using epoxy.

A non-limiting embodiment of the present invention is described in more detail below with reference to the drawings, in which FIG. 1 is a schematic representation of a method for obtaining elements of an enthalpy exchanger according to the present invention;

fig. 2 is a schematic representation of an enthalpy exchanger according to the present invention, or a part thereof containing a plurality of elements of an enthalpy exchanger according to the present invention;

fig. 3 is an SEM (scanning electron microscopy) micrograph of a cross section of a part of an intermediate product obtained by carrying out the process for producing an enthalpy exchanger element according to the present invention;

fig. 4 is an SEM micrograph of a cross section of a portion of an enthalpy exchanger element obtained by the method of the present invention;

fig. 5 is an SEM micrograph similar to that shown in FIG. 3, which shows, on a larger scale, a cross section of a smaller portion of an intermediate product obtained by carrying out the method for producing an enthalpy exchanger element according to the present invention; and fig. 6 is an SEM micrograph similar to that shown in FIG. 4, which shows, on a smaller scale, a cross-sectional view of a major part of an enthalpy exchanger element obtained by the method of the present invention.

In FIG. 1 shows a schematic representation of a method for obtaining elements of an enthalpy exchanger according to the present invention. Cross-sections of intermediate products are shown, i.e. the results of each of the stages S1, S2 and S3.

In the first stage S1, a breathable sheet component 1 is provided, containing voids or holes 2.

In the second step S2, both sides 1a, 1b of the sheet component 1 are laminated with a thin polymer film 3, 4 with water vapor permeability properties.

In the third step S3, the laminated sheet component 1 is molded into a desired shape having a three-dimensional corrugated pattern 5.

The sheet component 2 is a nonwoven web containing only thermoplastic fibers or a combination of thermoset fibers and thermoplastic fibers. The web may contain bicomponent fibers along with conventional thermoset and/or thermoplastic fibers.

The thin polymer film 3, 4 is a multilayer film which may contain a sequence (not shown) of polymer layers made from different types of polymers.

The forming step S3 is a thermoforming step, preferably a vacuum forming step.

The thermoforming step S3 uses at least a first mold section (e.g. a lower tool, not shown) containing the first corrugated structures, together

- 7 039572 limiting the predetermined corrugated relief 5 of the element E, E' of the enthalpy exchanger to be manufactured. Along with at least the first mold section, a second mold section (e.g., top tool, not shown) is used in thermoforming step S3, comprising second corrugated structures in addition to the first corrugated structures and/or a forming vacuum jointly limiting a predetermined corrugated relief element E, E' of the enthalpy exchanger to be manufactured.

The obtained element E of the enthalpy exchanger, containing the first thin polymer film 3 on the first side 1a of the sheet component 1 and the second thin polymer film 4 on the second side 1b of the sheet component 1, contains a corrugated structure 5 with alternating squeezed parts 5a and squeezed/stretched parts 5b. The squashed portion 5a extends in a first direction (horizontal direction in FIG. 1) and the squashed/stretched portions 5b extend in a second direction different from the first direction. The angle α between the first direction and the second direction in the corrugated pattern 5 of the enthalpy exchange element E is preferably 90 to 120°, preferably 95 to 105°, a corresponding example is shown in FIG. 1. Alternatively, in contrast to the example shown in FIG. 1, the angle α between the first direction and the second direction in the corrugated pattern 5 of the enthalpy exchange element E is 80 to 90°, preferably 85 to 90°.

In FIG. 2 shows a schematic representation of a first type E1-E2-B3 enthalpy exchanger or a second type E1'-E2'-B3' enthalpy exchanger according to the present invention. The first type E1-E2-B3 comprises a plurality of enthalpy exchanger elements B1, B2, B3 in which the first resin thin film 3 and the second resin thin film 4 (FIG. 1) are films of the same type. The second type B1'-E2'-B3' comprises a plurality of enthalpy exchanger elements E1', E2', B3', in which the first polymer thin film 3 and the second polymer thin film 4 (Fig. 1) are films of different types, including the case when one of the two films 3, 4 has zero thickness, i.e. the enthalpy exchange element contains only one thin polymer film 3 or 4 on one side 1a or 1b of the sheet component 1.

In FIG. 2 does not show the outer walls of the casing/package of the enthalpy exchanger E1-E2-B3 or B1'-E2'-B3'. The air intake/air outlet parts (not shown) of the enthalpy exchanger E1-E2-B3 or B1'-E2'-B3' are provided with reliefs for air distribution in such a way that the air flows in adjacent ventilation ducts in the enthalpy exchanger E1-E2-B3 or B1'- E2'-B3' run in opposite directions as shown by the symbol O indicating airflow moving towards the viewer and the symbol X indicating airflow moving away from the viewer.

In FIG. 3 shows a SEM (Scanning Electron Microscopy) micrograph of a cross section of a breathable sheet component 1 whose upper side 1a is laminated with a first thin resin film 3 and whose bottom side 1b is laminated with a second thin resin film 4 as a result of step b) of the method according to the present invention.

The laminating step b) may include bonding, preferably thermal bonding, and/or gluing the thin polymer films 3, 4 to the sheet component 1. A thermoplastic adhesive (hot melt adhesive) may be used to form a bond between the polymer film 3 and 4 and the sheet component 1.

The sheet component 1 is a non-woven fabric containing a plurality of fibers 6. The fibers 6 can be thermoplastic fibers alone or a combination of thermoset fibers and/or mineral fibers on one side and thermoplastic fibers on the other side. Most preferably, the web includes multicomponent or bicomponent fibers along with standard thermoset and/or thermoplastic fibers. As can best be seen from a comparison of FIG. 3 from FIG. 4, the fibers 6 of the nonwoven sheet component 1 shown in FIG. 3 are less densely packed than the fibers 6 of the nonwoven sheet component 1 of the enthalpy exchange element shown in FIG. 4.

In FIG. 4 is an SEM micrograph of a cross section of a portion of an enthalpy exchanger element E obtained by molding the laminated sheet component 1 shown in FIG. 3, shaped into a three-dimensional corrugated pattern as a result of step c) of the method of the present invention.

Forming step c) may be a shirring step or a thermoforming step, preferably a vacuum forming step. In the thermoforming step, at least a first mold section (e.g., bottom tool, not shown) is provided and used, comprising first corrugated structures delimiting or co-delimiting a predetermined corrugated pattern of the enthalpy exchanger element E, E' to be manufactured. In addition to at least the first mold section, a second mold section (e.g., top tool, not shown) can be provided in the thermoforming step containing second corrugated structures in addition to the first corrugated structures and/or forming vacuum, together limiting the predetermined corrugated relief of the element E, E' of the enthalpy exchanger to be manufactured.

The first mold section (eg, bottom tool) may include nozzles or through holes pneumatically connected to a vacuum source providing vacuum for the vacuum forming step.

In addition to the first mold section and/or the second mold section used in the molding step c), nozzles connected to a compressed air source can preferably be used to maintain the vacuum in the vacuum molding step. Such nozzles can be provided proximate, preferably adjacent, the first mold section and/or the second mold section. The compressed air source preferably comprises an air heating device for heating the compressed air.

The combined use of a first tool and a vacuum source in the thermoforming step c) can be supplemented by a second tool and/or compressed air source, preferably with an air heating device. As a result, by using at least some of these additional components, the sheet component 1 laminated by the first thin resin film 3 and optionally by the second thin resin film 4 can be pressed against the first corrugated structures of the first mold section with greater force, thereby obtaining , the enthalpy exchanger element E with the best impression of the first corrugated structures of the first mold section delimiting or jointly delimiting the predetermined corrugation pattern of the enthalpy exchanger element E to be manufactured.

The fibers 6 of the sheet component 1 of the enthalpy exchange element E are much denser packed than the fibers of the sheet component 1 shown in FIG. 3. During step c) of shirring or thermoforming, the web-shaped sheet component 1 comprising the first polymer thin film 3 and the second polymer thin film 4 is compressed and heated. During the shirring or thermoforming step c) at least the thermoplastic fibers or the multicomponent or bicomponent fibers of the plurality of fibers 6 are softened or partially melted. As a result, after the thermoplastic fibers or multi-component or bi-component fibers of the plurality of fibers 6 are cooled and solidified, the web-shaped sheet component 1 comprising the first resin thin film 3 and the second resin thin film 4 becomes the element E of the enthalpy exchanger according to the present invention with more compact structure of fibers in the sheet component 1 in the form of a web and with a three-dimensional corrugated pattern.

In FIG. 5 shows an SEM micrograph similar to that shown in FIG. 3, which shows, on a larger scale, a cross-section of a smaller part of the breathable sheet component 1 in the form of a web, the top side 1a of which is laminated with a first thin plastic film 3 and the bottom side 1b of which is laminated with a second thin plastic film 4 as a result of step b) of the method according to the present invention

In FIG. 6 shows an SEM micrograph similar to that shown in FIG. 4, which shows, on a smaller scale, a cross-sectional view of most of the element E of an enthalpy exchanger obtained by the method of the present invention.

Positional designations:

a sheet component in the form of a web;

a - the first surface;

b - second surface;

- voids or holes;

- the first thin polymer film;

- the second thin polymer film;

- corrugation;

a - the compressed part;

b - compressed and/or elongated part;

S1 - provision stage;

S2 - lamination stage;

S3 - stage of molding (joint molding);

O - the direction of the air flow towards the observer;

X - the direction of the air flow in the direction from the observer;

- fiber;

α - angle (in corrugated relief).

- 9 039572

CLAIM

Claims (17)

CLAIM 1. A method for obtaining an enthalpy exchanger, including the steps: a) providing a breathable sheet component (1); b) laminating at least one side (1a, 1b) of the sheet component (1) with a thin polymer film (3, 4) with water vapor permeability properties, where the thin polymer film is a monolithic membrane; c) shaping the laminated sheet component (1) into the desired shape having a three-dimensional corrugated pattern (5, 5, ...); d) repeating the previous steps to obtain at least three laminated sheet components having a three-dimensional corrugated pattern, where at least three laminated sheet components having a three-dimensional corrugated pattern are stacked and attached to each other, with each of their respective corrugated patterns in parallel orientation forms parallel flow passages for fluids, where the molding step c) is a thermoforming step, where in the thermoforming step c) at least a first mold section is provided and used, containing the first corrugated structures, limiting or jointly limiting a given corrugated relief of the laminated sheet component of the enthalpy exchanger to be manufactured. 2. Method according to claim 1, characterized in that the sheet material of the sheet component (1) contains a polymer. 3. Method according to claim 1 or 2, characterized in that the sheet component (1) is a web, preferably a non-woven web. 4. Method according to claim 3, characterized in that a certain proportion, preferably at least 50% by weight, of the fibers (6) of the web are multicomponent, preferably bicomponent fibers. 5. Method according to any one of claims 1 to 4, characterized in that step b) of laminating comprises at least a step selected from bonding, preferably thermal bonding, sealing and gluing the thin polymer film (3, 4) to the sheet component (one). 6. Method according to any one of claims 1 to 5, characterized in that at least one thin plastic film (3, 4) on at least one side (1a, 1b) of the sheet component (1) is an airtight plastic film. 7. Method according to any one of claims 1 to 6, characterized in that the thin polymer film (3, 4) is a multilayer film containing a sequence of polymer layers made from different types of polymers. 8. The method according to claim 7, characterized in that the polymer type of each polymeric layer is selected from the group consisting of polyester-ether copolymer, polyesteramide and polyesterurethane. 9. The method according to claim 7 or 8, characterized in that the total thickness of the thin polymeric multilayer film is from 5 to 200 µm, more preferably from 10 to 150 µm. 10. Method according to any one of claims 7 to 9, characterized in that the thickness of each individual polymeric layer within the thin polymeric multilayer film is from 1 to 20 µm, preferably from 4 to 20 µm and more preferably from 4 to 15 µm. 11. The method according to any one of claims 1 to 10, characterized in that the thermoforming step is a vacuum forming step. 12. The method according to any one of claims 1 to 11, characterized in that, in step c) of thermoforming, a second mold section is provided and used, comprising, in addition to the first corrugated structures, second corrugated structures jointly delimiting a predetermined corrugated pattern of the laminated sheet component of the enthalpy exchanger to be manufactured. 13. Method according to any one of claims 10 to 12, characterized in that, in step c) of thermoforming, nozzles connected to a source of compressed air are provided and used. 14. The method according to claim 13, characterized in that said nozzles are placed in the vicinity of the first mold section and/or the second mold section. 15. An enthalpy exchanger obtained by the method according to claim 1, containing at least three sheet-like or plate elements (E1, E2, E3; E1', E2', E3') of the enthalpy exchanger and a given thermoformed three-dimensional corrugated relief (5, 5, ...), wherein the first thin plastic film (3) is laminated to the first side (1a) of the sheet component (1) and/or the second thin plastic film (4) is laminated to the second side (1b) of the sheet component (1), with In this case, both thin polymer films (3, 4) have water vapor permeability properties and are monolithic membranes, where at least three laminated sheet components having a three-dimensional corrugated relief are stacked and attached to each other, while each of their respective - 10 039572 corrugated reliefs in parallel orientation form parallel flow passages for fluids. 16. An enthalpy exchanger according to claim 15, characterized in that the first polymer thin film (3) and the second polymer thin film (4) are identical to each other. 17. An enthalpy exchanger according to claim 15, characterized in that the first polymer thin film (3) and the second polymer thin film (4) are different from each other.