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EP-4736987-A1 - FILTER ELEMENT

EP4736987A1EP 4736987 A1EP4736987 A1EP 4736987A1EP-4736987-A1

Abstract

The present disclosure relates to an air filter element (1) for filtering polluted air, which comprises a perforated top layer (21) which comprises a number of first openings (211) enabling unfiltered air to enter the lattice structure. The lattice structure (2) further comprises a perforated bottom layer (22) which comprises a number of second openings (221) enabling filtered air to exit the lattice structure and a plurality of connection elements (23), which extend from the perforated top layer (21) to the perforated bottom layer (22). The air filter element (1) further comprises electrostatically charged fibers (3), which are arranged such that they cover the number of first openings (211) and / or the number of second openings (221) and are configured to electrostatically attract particles from the polluted air passing through the air filter element. The present disclosure further relates to a method for producing an air filter element (1), an air filtering device (4) for filtering polluted air, a heat recovery unit (6) and the use of an air filter element (1) for the air filtering device (4) or the heat recovery unit (6).

Inventors

  • Poppelaars, Ruud

Assignees

  • Zehnder Group International AG

Dates

Publication Date
20260506
Application Date
20251103

Claims (16)

  1. An air filter element (1) for filtering polluted air, the air filter element (1) comprising a. a lattice structure (2) comprising: i. a perforated top layer (21), which defines a top surface (TS) of the lattice structure (1) and which comprises a number of first openings (211) enabling unfiltered air to enter the lattice structure; ii. a perforated bottom layer (22), which defines a bottom surface (BS) of the lattice structure (2) and comprises a number of second openings (221) enabling filtered air to exit the lattice structure; iii. a plurality of connection elements (23), which extend from the perforated top layer (21) to the perforated bottom layer (22) and interconnect the perforated top layer (21) to the perforated bottom layer (22), and b. electrostatically charged fibers (3), which are arranged such that they cover the number of first openings (211) and / or the number of second openings (221) and are configured to electrostatically attract particles from the polluted air passing through the air filter element.
  2. The air filter element (1) according to claim 1, wherein the electrostatically charged fibers (3) are arranged at least partially within the lattice structure (2) between the perforated top layer (21) and the perforated bottom layer (22), the electrostatically charged fibers (3) preferably extend along a longitudinal direction (LF) and are arranged within the lattice structure (2) between the perforated top layer (21) and the perforated bottom layer (22) in a wavy manner.
  3. The air filter element (1) according to claim 2, wherein the electrostatically charged fibers (3) are arranged such they form a woven structure with the connection elements (23).
  4. The air filter element (1) according to claim 2 or 3, wherein the electrostatically charged fibers (3) are bonded to the connection elements (23) by an adhesive or are bonded to the connection elements (23) by a thermal bond.
  5. The air filter element (1) according to any of the preceding claims, wherein the perforated top layer (21) and / or the perforated bottom layer (22) is a web (5), and wherein the perforated top layer (21) and / or the perforated bottom layer (22) is/are made from a flexible material, preferably from a thermoplastic elastomer, with the web (5) preferably being formed by a plurality of strings (51) made from intertwined strands and a majority of the connection elements (23) are attached to the strings (51).
  6. The air filter element (1) according to any of the preceding claims, wherein a majority of the connection elements (23) is a flexible fiber which is bonded to the perforated top layer (21) and the perforated bottom layer (22), preferably thermally or by an adhesive, with the connection elements (23) preferably extending along a longitudinal direction (LC) and having a length being from 3 mm to 100 mm, preferably from 20 mm to 50 mm and more preferably from 15 mm to 35 mm and / or a diameter being from 10 µm to 250 µm, preferably from 25 µm to 150 µm, more preferably from 50 µm to 100 µm.
  7. Method for producing an air filter element (1), preferably an air filter element (1) according to any of claims 1 to 6, comprising at least the following method steps: a. Providing a lattice structure (2) comprising: i. a perforated top layer (21), which defines a top surface (TS) of the lattice structure (1) and which comprises a number of first openings (211) enabling unfiltered air to enter the lattice structure; ii. a perforated bottom layer (22), which defines a bottom surface (BS) of the lattice structure (2) and comprises a number of second openings (221) enabling filtered air to exit the lattice structure; iii. a plurality of connection elements (23), which extend from the perforated top layer (21) to the perforated bottom layer (22) and interconnect the perforated top layer (21) to the perforated bottom layer (22), and b. Arranging electrostatically charged fibers (3) in the lattice structure (2), which electrostatically charged fibers (3) are arranged such that they cover the number of first openings (211) and / or the number of second openings (221) and are configured to electrostatically attract particles from the polluted air passing through the air filter element.
  8. Method according to claim 7, wherein the lattice structure (2) is inherently stable, so that the perforated top layer (21) is separated from the perforated bottom layer (22) by means of the plurality of connection elements (23), preferably inherently stable even before arranging the electrostatically charged fibers (3) in the lattice structure (2), the electrostatically charged fibers (3) are preferably blown into the lattice structure (2).
  9. Method according to any of claims 7 or 8, wherein the electrostatically charged fibers (3) are arranged such they form a woven structure with the connection elements (23) and/or are bonded to the connection elements (23) by an adhesive or are bonded to the connection elements (23) by a thermal bond.
  10. An air filtering device (4) for filtering polluted air, the air filtering device (4) extends along a flow path (FP) and comprises along the flow path a. a first air filter unit (41), which comprises at least one air filter element (1) according to any one of claims 1 to 6 or an air filter element (1) obtained by the method according to any one of claims 7 to 9; b. an air moving unit (42), which is configured to move unfiltered air from outside the air filtering device through the first air filter unit (1) which is configured to filter the outside air.
  11. The air filtering device (4) according to claim 10, wherein the air filter element (1) is arranged within the first air filter unit (41) inclined with respect to the flow path (FP), preferably by an angle (α) being from 10° to 80°, preferably between 15° and 45° and more preferably between 20° and 35°.
  12. The air filtering device (4) according to claim 10 or 11, wherein the first air filter unit (41) comprises compartments (411), which are each configured to receive at least two air filter elements (1), with the compartments (411) preferably being V-shaped and the two air filter elements (1) being arranged opposite to each other in the V-shaped compartments.
  13. The air filtering device (4) according to any of claims 10 to 12, wherein the air filtering device (4) comprises a second air filter unit (43) which is arranged along the flow path (FP) downstream of the first air filter unit (41) and is configured to clean the air pre-cleaned by the first air filter unit (41), with the second air filter unit (43) preferably comprising a fine filter element (431) configured to filter out particle matter (PM) of being 10 micrometers or smaller.
  14. A heat recovery unit (6) comprising a. a heat exchanger (61) comprising first flow paths (611) and second flow paths (612) for heat exchange between at least two fluids, preferably in the form of two air streams, b. a first fan (62) being configured to actively move a first fluid (F1) through the first flow paths (611) of the heat exchanger (61) and a second fan (63) being configured to actively move a second fluid (F2) through the second flow paths (612) of the heat exchanger (61); c. a first air filter unit (64), which comprises at least one air filter element (1) according to any one of claims 1 to 6 or an air filter element (1) obtained by the method according to any of claims 7 to 9.
  15. The heat recovery unit (6) according to claim 14, wherein the first fluid (F1) is outside air (OA) and the first air filter unit (64) is arranged upstream of the heat exchanger (61) and is configured to pre-clean the outside air (OA) before entering the heat exchanger (61) and the heat recovery unit (6) preferably comprises a second air filter unit (65) which is arranged downstream of the heat exchanger (61) and is configured to clean the outside air (OA) exiting the heat exchanger (61).
  16. Use of an air filter element (1) according to any of claims 1 to 6 or an air filter element (1) obtained by the method according to any of claims 7 to 9 for an air filtering device (4, 4') according to any of claims 10 to 13 and / or for a heat recovery unit (6) according to any of claims 14 to 16.

Description

FIELD OF THE DISCLOSURE The present disclosure relates to an air filter element for filtering polluted air, a method for producing an air filter element, an air filtering device, a heat recovery unit and a use of the air filter element for the air filtering device or the heat recovery unit. BACKGROUND OF THE DISCLOSURE Air filter elements and air filtering devices for filtering polluted or contaminated air are known. Known air filter elements typically comprise fibrous or porous materials, which are supposed to remove particulates such as smoke, dust, pollen, mold, viruses and bacteria from an airstream passing through the air filter element. Besides removing particulates, filter elements can in addition comprise an adsorbent or catalyst such as charcoal which can also remove odors and gaseous pollutants such as volatile organic compounds or ozone. These air filter elements are used in applications where air quality is important, for example in building ventilation systems. SUMMARY OF THE DISCLOSURE Air filtering devices suitable to be arranged in a volume of air are known. Conventional air filtering devices mostly comprise an air moving unit, like a fan, which guides an air flow through at least one filter in a forced manner, for filtering the respective volume of air. After a predetermined time and in particular dependent on the degree of contamination of the filtered volume of air, the air filter element needs to be replaced. The replacement is conventionally either done in predetermined time intervals by respective personnel, which typically determines the replacement intervals according to their personal experience. The conventional result is that many times the replaced air filter element is not contaminated enough which would justify its replacement or the air filter element is contaminated to much which results in a poor cleaning of the air. The overall result is that the maintenance personnel controls and maintains the respective air filter devices rather more often than necessary to avoid a poor cleaning result. This further results in high maintenance costs because manually checking the different air filtering devices is labor intense. To increase the lifespan of industrial air filter elements and thereby be able to stretch the maintenance intervals of the air filtering device, pre-filters can be used. A pre-filter is typically a filter configured to remove larger particles from the volume of air before the volume of air reaches the main filter. Pre-filters are installed as the first stage of filtration, designed to capture the larger particles and prevent them from entering the air filter element. Pre-filters are foreseen to filter out particulates such as dust, hair, insects, pollen and various fibers. Air filtering devices equipped with pre-filters are used in buildings, transportation, public areas and industrial workplaces. Pre-filters are typically made from a variety of materials, such as foam, mesh, or fiberglass. The choice of material depends on the specific requirements of the air filtering device and the types of particles the pre-filter needs to capture. Regardless of the material, the primary function of a pre-filter is to trap larger particles before they reach the more advanced main filter element in the air filtering device. An objective of the present disclosure can be seen in proving an air filter element with an improved lifespan and an air filtering device with prolonged maintenance intervals. The present disclosure relates to an air filter element for filtering polluted air. The air filter element typically comprises a lattice structure which can comprise a perforated top layer, which defines a top surface of the lattice structure and comprises a number of first openings, enabling unfiltered air to enter the lattice structure. The lattice structure typically further comprises a perforated bottom layer, which defines a bottom surface of the lattice structure and comprises a number of second openings, enabling filtered air to exit the lattice structure. The lattice structure typically further comprises a plurality of connection elements, which extend from the perforated top layer to the perforated bottom layer and interconnect the perforated top layer to the perforated bottom layer. The lattice structure is typically in the form of a sandwich structure with the connection elements being sandwiched between the perforated top layer and the perforated bottom layer. The lattice structure may be inherently stable, so that the perforated top layer is separated from the perforated bottom layer by means of the plurality of connection elements. Inherently stable is to be understood that the perforated top layer does not come in contact with the perforated bottom layer even without electrostatically charged fibers being arranged between the perforated top layer and the perforated bottom layer. Good results can be achieved, when the air filter element further comprises electrostatically