Abstract
A system for air decontamination in a three-dimensional space described herein includes an air inlet for drawing in air, an air outlet for administering filtered air, and a filter device for filtering air prior to administration through the air outlet, the system is configured to draw air in a substantially vertical laminar flow from a ground of the space to the air inlet. A filter device for filtering ultrafine particles from a gas described herein includes a first filter medium for absorbing polar liquids but not ultrafine particles; in fluid communication with a second filter medium for absorbing ultrafine particles; and a gas outlet, the first filter medium is configured to allow vaporization of the absorbed polar liquids; the device is configured to guide the gas from the first to the second filter medium and through the second filter medium; and the second filter medium forms the gas outlet.
Claims
1. A system for air decontamination in a three-dimensional (3D) space, the system comprising (I) at least one air inlet positioned essentially at a top of the 3D space and configured to draw in air from the 3D space, (II) at least one air outlet configured to administer filtered and optionally fresh air to the 3D space, (III) a filter device in fluid communication with the at least one air inlet and outlet, configured to filter ultrafine particles from the air drawn in through the air inlet, and configured to at least partially exhaust the filtered air through the air outlet, wherein the system is configured to draw air in a substantially vertical laminar flow substantially from a ground of the 3D space, into the air inlet.
2. The system according to claim 1, wherein the 3D space is a closed indoor space, the at least one air inlet is positioned essentially above a height of a standing or sitting person or essentially at a ceiling of the space, and the at least one air outlet is positioned essentially below the height of the standing or sitting person or on the ground of the 3D space.
3. The system according to claim 1, wherein the substantially vertical laminar flow has an average speed of about 0.1 to 0.2 m/s or 0.02 to 0.4 m/s.
4. The system according to claim 1, wherein the system is configured to exchange the volume of the 3D space between 2 to 6 times per hour.
5. The system according to claim 1, wherein the system is configured to have an average air speed of about 0.1 to 0.2 m/s or about 0.05 to 0.2 m/s at the at least one air inlet.
6. The system according to claim 1, wherein the system is configured to have an average air speed of about 0.01 to 0.2 m/s at the at least one air outlet.
7. The system according to claim 1, wherein the at least one air inlet comprises a perforated member at least partially covering one or more air inlet(s) and having openings through which the air is drawn from the 3D space, the at least one air inlet comprises a perforated member configured to distribute the air intake and to avoid areas where air is trapped above the air inlet, the at least one air inlet comprises a perforated member which forms an essentially horizontal, an essentially flat plane, or both an essentially horizontal and flat plane configured to draw air homogeneously over the whole surface of the perforated member, or a combination thereof.
8. (canceled)
9. The system according to claim 7, wherein the perforated member forms a ceiling of the 3D space.
10. The system according to claim 1, wherein the at least one air outlet comprises a porous membrane through which the filtered air is administered to the 3D space.
11. The system according to claim 10, wherein the porous membrane is configured to reduce a velocity of the filtered air upon administration to the 3D space by a factor of about 50 to 200.
12. The system according to claim 10, wherein the porous membrane has (a) a porosity of about 40 to 90%; (b) a pore size of about 0.01 to 1 mm; (c) a thickness of about 0.1 to 2 mm; (d) a density of about 100 to 200 g/m.sup.2; or (e) a combination thereof.
13. The system according to claim 10, wherein the porous membrane comprises or is made of a fabric, a cloth, a foam, a perforated plate or a combination thereof.
14. The system according to claim 1, further comprising at least one of: a device for moving gas, at least one device for regulating the ratio of fresh and filtered air, a CO.sub.2-measuring device, a heat exchanger configured to exchange heat between filtered and fresh air, or means for thermally supporting, increasing, or supporting and increasing the substantially vertical laminar flow.
15. The system according to claim 14, wherein the system comprises means for warming the filtered air, the fresh air, or both the filtered air and the fresh air, prior to, during or after administration to the 3D space.
16. The system according to claim 15, wherein the means for warming the filtered air, fresh air, or both the filtered air and fresh air, warm the air by about 5 to 20° C. above the temperature in the 3D space.
17. The system (according to claim 1, wherein the 3D space is at least one of a space formed around a person or is further defined by structural means.
18. The system according to claim 1, wherein the 3D space (101) is a space formed around a person standing or sitting in a room, or around a person or around a person's head, lying on a bed.
19. A filter device for filtering ultrafine particles from a gas, the filter device being a second filter medium for absorbing ultrafine particles, wherein the second filter medium is a cell-type filter medium having a gas entry and exit side and is (a) coated with a hydrophobic material on the gas entry side, or (b) coated with a hydrophilic material on the gas exit side.
20. The filter device according to claim 19, wherein the cell-type filter medium is coated with (i) a silver-comprising coating, (ii) copper-comprising coating, or (iii) both (i) and (ii).
21. (canceled)
22. (canceled)
23. (canceled)
24. (canceled)
25. (canceled)
26. (canceled)
27. (canceled)
28. The system for air decontamination in a three-dimensional (3D) space according to claim 1, wherein the filter device comprises a cell-type filter medium for absorbing ultrafine particles, wherein the cell-type filter medium has a gas entry and exit side and is (a) coated with a hydrophobic material on the gas entry side, or (b) coated with a hydrophilic material on the gas exit side.
29. (canceled)
30. (canceled)
31. A method for air decontamination in a three-dimensional (3D) space, the method comprising: (a) providing or installing a system according to claim 1; and (b) drawing air in a substantially vertical laminar flow substantially from a ground of the 3D space into the air inlet of the system.
32. The system according to claim 1, wherein the at least one air outlet is (i) positioned essentially at the ground of the 3D space, (ii) the filter device is further configured to filter ultrafine particles from fresh air, or (iii) both (i) and (ii).
33. The system according to claim 17, wherein the structural means are curtains, shields, or a hood-shaped enclosure.
34. The method according to claim 31, wherein the 3D space is a medical facility or a space, room, bed, or seat in a medical facility.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0151] In the following, the invention will be described by reference to the figures, none of which are to be interpreted as limiting the scope of the present invention.
[0152] FIG. 1 shows an exemplary system for air decontamination in a three-dimensional (3D) space according to the present disclosure.
[0153] FIG. 2 shows the substantially laminar flow around persons in the 3D space in an embodiment of the present disclosure.
[0154] FIG. 3 shows a specific suction zone or ventilation zone within the 3D space in an embodiment of the present disclosure.
[0155] FIG. 4 shows a specific suction zone or ventilation zone created by an embodiment of the system of the present disclosure that creates a 3D space around a person.
[0156] FIG. 5 shows an exemplary close-up of the air intake part of the system described herein.
[0157] FIG. 6a shows an exemplary close-up of the air intake part of the system described herein.
[0158] FIG. 6b shows an exemplary close-up of the air intake part of the system described herein.
[0159] FIG. 7a shows an exemplary embodiment of the air outlet of the system described herein.
[0160] FIG. 7b shows an exemplary embodiment of the air outlet of the system described herein.
[0161] FIG. 7c shows an exemplary embodiment of the air outlet of the system described herein.
[0162] FIG. 8a shows a side view of an exemplary system described herein in a 3D space.
[0163] FIG. 8b shows the corresponding top view of the same 3D space of FIG. 7a.
[0164] FIG. 9a shows a schematic top view of the room for the experimental set up of Example 1.
[0165] FIGS. 9b and 9c are photographs showing part of exemplary air outlets.
[0166] FIG. 9d shows the arrangement of the nebulizer (round circle) and the 2 sensors (squares, S2 sensors as outlined in the example) used in the example.
[0167] FIG. 9e shows the air inlets (transparent cones) arranged at the ceiling.
[0168] FIG. 10 shows a 3D uplift zone around a person.
[0169] FIG. 11 shows an exemplary system for creating a 3D space around a person.
[0170] FIG. 12 shows a further embodiment of the present disclosure for creating a curtain of airflow.
[0171] FIG. 13 shows an exemplary system for avoiding infections among people in a given space.
[0172] FIG. 14 shows an exemplary filter device according to the present disclosure.
[0173] FIG. 15 shows an exemplary filter device according to the present disclosure.
[0174] FIG. 16 shows an exemplary embodiment of the filter device.
[0175] FIG. 17a shows an exemplary first filter housing.
[0176] FIG. 17b shows an alternative embodiment for the second filter housing.
[0177] FIG. 17c shows an exemplary first filter housing.
[0178] FIG. 18 illustrates an alternative filter device according to the present invention.
DETAILED DESCRIPTION
[0179] In the following, the invention will be described by examples with reference to the figures and examples, none of which are to be interpreted as limiting the scope of the present invention.
[0180] FIG. 1 illustrates a system (100) for air decontamination in a three-dimensional (3D) space (101) according to the present invention. The substantially vertical laminar flow, i.e. the relatively slow and turbulence-free air flow, that effectively channels particle-contaminated air up and away from a person is shown as exemplary arrows (106). The direction of arrows (106) is substantially vertical, from a lower part of the 3D space to the upper part of the 3D space, but the arrows do not realistically reflect the density of the laminar flow. Exemplary average air speeds for the laminar flow (106) are from 0.02 to 0.4 m/s or optionally at most about 0.1 to 0.2 m/s. The air inlet (102) may be of any shape suitable for drawing in air and is not limited to the cones depicted. Also, the number of air inlets is not to be interpreted as being limited by the illustration. An exemplary air speed of the air entering the air inlet (102) at the dotted line is about 0.1 to 0.2 m/s, or about 0.02-0.4 m/s. The air inlets (102) are fluidly connected to a ducting in which the drawn in air is collected and moved (indicated by arrows) towards a filter device (200). Of course, multiple filter devices and multiple sets of tubes ducting the air may be present. Fresh air (105) may be admitted from outside the 3D space, and this can be controlled by a device for regulating the ratio of fresh and filtered air (107), e.g. a gate, flap or valve. The fresh air may or may not be passed through the filter device (200). Air drawn from within the 3D space (101) and preferably passed through the filter device (200) can be partially exhausted to the exterior of the 3D space, e.g. at the control of a similar device (108) described for the admittance of fresh air. A device for moving gas (208), if present, can be positioned before or aft of the filter device (200). For example, any axial, radial or half-radial blower or a fan that pushes or draws air can be used. An optional heat exchanger (123) can be used to exchange heat between the fresh and exhaust air to either heat or cool the fresh air. After passing through the filter device (200), the air (recirculated and filtered air (104) and optionally fresh air (105)) is admitted to the 3D space via the air outlet(s) (103). Only one air outlet is illustrated but the system may comprise multiple air outlets in various positions which may or may not be interconnected. It is emphasized that the air outlets (103) are not necessarily arranged such that they actively “blow” air upwards the air inlets (102) to cause a laminar flow towards the air inlets (102). The air outlets (103) are shown opposite the air inlets (102) for illustration purposes only, but the air outlets do not need to be positioned opposite the air inlets (in vertical direction). Rather, the air outlets (103) but can be positioned anywhere within the 3D space, optionally in the bottom part, as long as their position allows for a substantially vertical laminar flow to occur towards the air inlets, e.g. around a person in the 3D space, which applies to all figures, embodiments and aspects disclosed herein. The air outlets (103) are optionally configured such that the outflowing air assists a substantially vertical laminar flow towards the air inlets (102). The air outlets (103) are optionally positioned at least below the heads of persons in the 3D space, optionally at, on or within the bottom of the 3D space. An exemplary air speed of the air exiting the air outlet (103) at the dotted line is about 0.01 to 0.2 m/s, optionally about 0.05 to 0.15 m/s.
[0181] Although the parts of the system that comprise the filter, fresh and exhaust air tubes and corresponding features are shown outside of the 3D space, they can be located anywhere close to or within the 3D space.
[0182] FIG. 2 illustrates the substantially laminar flow around persons in the 3D space. These persons may be standing, sitting or lying. The air outlets (103) are optionally positioned at least below the heads of persons in the 3D space, optionally at, on or within the bottom of the 3D space. The description provided for FIG. 1 applies for the remaining features of FIG. 2.
[0183] FIG. 3 shows a specific suction zone or ventilation zone (119) within the 3D space (101). In other words, the 3D space (101) is segmented into partial 3D spaces (119) by defining specific suction/ventilation zones. The zone is primarily defined by the position of the air inlet (102) and the location of the person or heated object (heated as described above). Optionally, the air outlet (103) can assist in defining the suction/ventilation zone and the partial 3D space. As noted above for FIG. 1, the air outlets (103) are shown opposite the air inlets (102) for illustration purposes only, but the air outlets do not need to be positioned opposite the air inlets (in vertical direction). Additionally, further structural means such as, e.g., walls, curtains or shields (not shown) can be used to create or define the segmented partial 3D space (119). The person may be standing, sitting on a chair or lying on a bed/sofa or be in any other position. The description provided for FIG. 1 applies for the remaining features of FIG. 3.
[0184] FIG. 4 illustrates a specific suction zone or ventilation zone created by a system (100) of the present invention that creates a 3D space (101) around a person (213). The air inlet (102) can form a hood-shaped enclosure (209) that can be placed over a person's head to support the isolating effect of the suction-created laminar flow (106) around the person's head. Connecting means (211), e.g. a tube or hose, can be installed between the air inlet (102)/hood-shaped enclosure (209) and the filter device (200) to allow positioning of the filter device (200) at a convenient location, e.g. attached to a chair, wheelchair or bed. Filtered air is then at least partially passed through the air outlet (103) positioned below the person's head to create the laminar flow (106).
[0185] To further support the isolating effect of the uplift zone, a structural barrier (210), e.g. a transparent visor, is optionally positioned in front of the person's mouth and nose to prevent that particles emitted at high velocities (e.g. by sneezing or coughing) penetrate the laminar flow (106). Alternatively or additionally, a face mask can be used for the same purpose.
[0186] Depicted in FIG. 4 is a wheelchair (212) but any other seating or laying device is encompassed by this disclosure, e.g. a regular chair, a bed or a hospital bed. The air outlet (103) may include a porous membrane (not shown) and can constitute a cushion of a seat or mattress of a bed. Alternatively, the air outlet (103) may also be positioned in the frame of the bed or chair.
[0187] The exhausted and filtered air from filter device (200) can also be partially exhausted away from the person (213).
[0188] FIG. 5 illustrates an exemplary close-up of the air intake part of the system (100) described herein. The air inlets (102) (two are shown, but any number is included in the scope of this disclosure) can be attached to one or more perforated members (109) (one shown) including openings (110) through which the air of the laminar air flow (106) is drawn into the air inlet (102). The perforated member (109) (e.g. evenly) distributes the air intake into the air inlets and can also avoid “dead zones”, i.e. areas where air is trapped above an air inlet. The area of the perforated member (109) between the air inlets (102) may be sealed against passing air by sealing means (113). The perforated member (109) may also extend further on the sides beyond the cross section of the air inlet (102) (not shown). For example, the assembly of FIG. 5 may be positioned above a person in a 3D space, e.g. a person sitting at a desk or lying in a bed.
[0189] FIG. 6a illustrates an exemplary close-up of the air intake part of the system (100) described herein. For achieving a uniform air suction across the perforated member (109), it is beneficial that the cross section (111) of the air inlet (102) is about the same or larger than the sum of the cross sections (112) of the openings (110) in the perforated member (109). Optionally, a ratio between a sum of a surface (112) defined by the openings (110) and a total surface (114) of the perforated member (109) is about 1:1 to 1:30, optionally about 1:2 to 1:20, optionally about 1:3 to 1:10. In other words, the sum of all distances (112) within the total surface (114) is compared to the total surface (114) of the perforated member. It is noted that the cross sections (112) are of the same size for illustration purposes only, however, these cross sections (112) may and optionally do vary across the perforated member (109) in order to achieve a uniform air suction across the member. Hence, alternatively or additionally, and as shown in FIG. 6b the uniform air suction across the perforated member (109) can be achieved by variation of the size of the cross sections (112) and their distribution across the perforated member (109). For example, the size of the cross sections (112) can be chosen such that the cross sections (112) furthest away from the cross section (111) of the air inlet (102) are larger compared to the cross sections (112) closer to the cross section (111) of the air inlet (102) which are smaller. This size difference of the cross sections (112) at different positions relative to the cross section (111) of the air inlet (102) means that the volume air flow (V2) through a cross section (112) closer to the cross section (111) of the air inlet (102) is essentially the same compared to the volume air flow (V1) through a cross section (112) further away from the cross section (111) of the air inlet (102), i.e. V1 equals about V2.
[0190] FIG. 7 illustrates different exemplary embodiments of the air outlet (103) of the system (100) described herein. FIG. 7a shows an air outlet (103) comprising a porous membrane (115) through which the air flows (arrow 106). The porous membrane may be single or multi-layered and made from different or the same materials. FIG. 7b shows an air outlet (103) comprising a porous membrane (115) made from two different components: a structural support layer such as, e.g. a perforated (metal) plate (116) comprising air openings, and a sieve or screen cloth/fabric or mesh laminate layer (117) through which the air passes and the air's velocity is reduced. Further layers as described herein may be comprised in the porous membrane (115) in different orders. FIG. 7c shows an air outlet (103) comprising a porous membrane (115) which itself comprises a foam (body) (118) that is optionally covered by a further layer (117) with sufficient stability as described above, e.g. a sieve or screen cloth/fabric or mesh laminates. Alternatives for the foam (118) include a semi-rigid porous structure such as 3D-spacer fabrics used for cushions or mattresses, e.g. if the air outlet (103) including the porous membrane constitutes a cushion of a seat or mattress of a bed. It is noted that when foams are used, it is advantageous that the porosity of the foam is higher than that of the further layer (117) with sufficient stability as described above to ensure a uniform air flow (106) across the air outlet.
[0191] FIG. 8a illustrates a side view of an exemplary system (100) described herein in a 3D space (101), e.g. a classroom, with active ventilation zones (120) where air is drawn into air inlets (102), e.g. through a perforated member (109) which can, e.g. form a ceiling. Alternatively, the air inlets (102) can be arranged to form an active ventilation zone without a perforated member (109) by their arrangement. Passive zones (119) refer to zones where no air passage is granted into the air inlets (102). Optionally, air outlets (103) can be positioned under the active ventilation zones (120) to increase the substantially vertical laminar air flow (106). However, and as noted above for FIG. 1, the air outlets (103) are shown opposite the air inlets (102) for illustration purposes only, but the air outlets do not need to be positioned opposite the air inlets (in vertical direction) and can be positioned, e.g. in the skirting board on the walls of the 3D space (e.g. classroom). FIG. 8b shows the corresponding top view of the same 3D space of FIG. 7a where the active ventilation zones (120) are indicated. Optionally, the system (100) can comprise an alternative or further active ventilation zone (121) around the perimeter of the 3D space which is formed in the same manner as the other ventilation zones (120), e.g. by the presence of air inlets (not shown) in combination with optional perforated members and/or air outlets (not shown) as described herein. The remaining parts of the system described in FIG. 1 are also not shown for simplicity.
[0192] FIG. 9a shows a schematic top view of the room for the experimental set up of Example 1. Shown are the air outlets (103), the air inlets (102) and the desks or tables (122) for people to sit in the room. FIG. 9b is a photograph showing part of the air outlets (103) which comprise a porous membrane made from cotton cloth with a linen binding as shown in FIG. 9c. FIG. 9d shows the arrangement of the nebulizer (round circle) and the 2 sensors (squares, S2 sensors as outlined in the example) used in the example. FIG. 9e shows the air inlets (transparent cones) arranged at the ceiling.
[0193] FIG. 10 illustrates the 3D uplift zone (216) around a person (217), optionally an infected person, optionally infected by a virus, which is formed by air flow (214) created by sucking air into a filter device (200) above the person.
[0194] In any embodiment and for all aspects, the filter device (200) may be movably positioned above the person (217) and it may follow the movements of the person. For example, a track system or any other mounting system that allows for movable positioning of the filter device (200) can be used above peoples' heads so that the filter device follows the peoples' movements. For example, in cues or workspaces where peoples' movements can be predetermined the filter device(s) follow the movement of the people. Movement or gathering of people where air cleaning is required can be determined, e.g. by monitoring CO.sub.2 emissions in a space of interest and moving the filter devices to the areas of increased CO.sub.2 emissions.
[0195] The exhausted and filtered air from the filter device (200) can either be exhausted away from the person (arrow 218) or it can be exhausted around the person creating a curtain of airflow (arrow 219) around the person, wherein the exhausted air is at least partially re-administered to the uplift zone and is recycled in the filter device. The percentage in the volume of air of the curtain of airflow that is re-administered to the uplift zone compared to the volume of air that is not re-administered can be in the range of, e.g. 10 to 40%. Exemplary air speeds for all embodiments, and only with reference to FIG. 10 for easier understanding, can be 0.1 to 0.2 m/s within the uplift zone (216) and/or 0.5 to 5 m/s for the exhausted air (arrow 219) to create the curtain of airflow mentioned above.
[0196] In all embodiments, if the filtered air is re-administered, it can be advantageous to include a CO.sub.2 sensor to determine if and what amount of fresh air must be supplied.
[0197] FIG. 11 illustrates a system (220) for creating a 3D space (215) around a person (213) and for filtering the air in that space by a filter device (200). A hood-shaped enclosure (209) can be placed over a person's head to support the isolating effect of the suction-created uplift zone around the person's head. Connecting means (211), e.g. a tube or hose, can be installed between the hood-shaped enclosure (209) and the filter device (200) to allow positioning of the filter device (200) at a convenient location, e.g. attached to a chair, wheelchair or bed.
[0198] To further support the isolating effect of the uplift zone, a structural barrier (210), e.g. a transparent visor, is positioned in front of the person's mouth and nose to prevent that particles emitted at high velocities (e.g. by sneezing or coughing) penetrate the uplift zone. Alternatively or additionally, a face mask can be used for the same purpose.
[0199] Depicted in FIG. 11 is a wheelchair (212) but any other seating or laying device is encompassed by this disclosure. The exhausted and filtered air from filter device (200) can be exhausted away from the person (213), it can be re-administered to 3D space (215), or it can be exhausted around the person creating a curtain of airflow around the person and towards the hood-shaped enclosure, resulting in the effects described above.
[0200] Exemplary air speeds for all embodiments, and only with reference to FIG. 11 for easier understanding, can be 0.1 to 0.2 m/s within the hood-shaped enclosure (209) and/or 0.5 to 5 m/s for the exhausted air to create the curtain of airflow mentioned above.
[0201] FIG. 12 illustrates a further embodiment of the present disclosure for creating a curtain of airflow and optionally concomitantly filtering ultrafine particles from the said airflow. For example, a curtain of airflow (214) can be created between two people (217), e.g. between an infected and non-infected person, which are positioned opposite each other at a table, desk or counter (221). The table, desk or counter (221) comprises an aperture (222), and an outlet (224) which is in fluid and air-tight communication with a second outlet (223) positioned above the table, desk or counter (221). Air is sucked into the aperture (222) and is optionally filtered by a filter device positioned in the table, desk or counter (221), in the second outlet (223) or anywhere in between these structures. The optionally filtered air is then at least partly released through second outlet (223) creating a curtain of airflow that separates the people (217) and avoids exchange of potentially contaminated exhaled air between the people (217). Additionally, part of the filtered air may also be released towards the people (217) standing at the table, desk or counter (221), which creates an additional airflow that further avoids mixing of exhaled air of the two people (217).
[0202] FIG. 13 illustrates a system for avoiding infections among people (217) in a given space (228), e.g. a working or production building (227), and for filtering air drawn from the building (227). Air is drawn up from above a person (217) creating an uplift zone (216) by the airflow around the person (214). The air is drawn up, for example, at speeds of about 0.1 to 0.2 m/s when measured above a person's head. A gas moving device (208), e.g. a ventilator, moves the air (arrows) into a filter device (200) as described herein. In the filter device (200), here, for example a tubular or rectangular elongated device of an essentially constant cross section or diameter, the air is first passed through the first filter medium (203) acting as an impaction filter, e.g. at velocities between about 0.5 and 5 m/s in order to filter and retain polar liquids and optionally particles of more than about 1 μm or 500 nm on or within the material of the first filter medium (203) after the collision of polar liquids and optionally particles with the first filter medium (203). Subsequently, the air moves towards and through the second filter medium (205) acting as filter at an air velocity of about 0.01 to 0.1 m/s, i.e. a reduced velocity in order to filter ultrafine particles such as viruses in the second filter medium (205). The second filter medium's shape and/or composition, e.g. tubes with alternating outlets (honeycomb) as described herein or any other known ultrafine particle filter, results in the reduction of the air velocity (based, e.g. on the large surface area of the tubes of the filter medium) while the air mass flow remains essentially constant through the filter device (200). The filtered air may then be re-administered to the internal space (208), see arrow (226).
[0203] FIG. 14 shows an exemplary filter device (200) according to the present invention. The first filter housing (202) forms a cavity (201) into which the gas enters (arrows refer to gas flow). For all embodiments, the shape of the first filter housing (202) can be any shape that is suitable for forming a housing. It may be of a box or tube shape and it may be tapered as shown in FIG. 14 or feature substantially parallel sides.
[0204] In some embodiments, the cavity (201) may comprise means for directing the gas flow towards the first filter medium (203) in order to ensure that polar liquids and/or particles (between 500 and 1000 nm diameter) as described herein come into contact with the first filter medium (203) and are, e.g., absorbed thereon or therein.
[0205] For example, the first filter housing may comprise a gas inlet and a gas exit either opposite each other or at any other relative positions in the first filter housing (202). The size of the gas inlet and outlet in FIG. 14 is non-limiting and may be adjusted by the skilled person, e.g. according to the desired air flow and/or size of the filter media.
[0206] The first filter housing (202) is partially covered with the first filter medium (203). The gas exits the first filter housing (202) via an opening (206) which may optionally also comprise a third filter medium as described herein which may, e.g. additionally straighten the gas flow and/or filter particles (e.g. between 500 and 1000 nm diameter) as described herein. The gas enters the second filter housing (204) which forms a cavity (207) and may, in some embodiments, be of any shape, e.g. a box or a cylinder. The second filter medium (205) partially forms the filter housing at the gas exit. In some embodiments, the second filter medium (205) can also completely form the filter housing.
[0207] FIG. 15 illustrates an exemplary filter device (200) according to the present invention, wherein the first filter medium (203) forms the first filter housing and the gas exits the first filter housing via the first filter medium (203) in direction of the second filter housing (204). Substantially all the gas to be filtered passes through the first filter medium (203) when moving into the second filter housing (204). Again, the second filter medium (205) can, e.g., also completely form the second filter housing (204).
[0208] FIG. 16 shows an embodiment of the filter device (200), wherein the first filter medium (203) either partially forms the first filter housing (202) or covers the first filter housing (202) on the side of the cavity (201). A gas moving device (208), e.g. a radial blower or any other gas moving device described herein, moves the gas and creates a rotational spin (circling arrows) within the first filter housing (202). For example, the shape of the gas moving device (208) may constitute flow-directing means which introduce and/or increase a rotational spin or turbulent flow of the gas within the first filter housing, for example also independent of the type of the gas moving device.
[0209] FIG. 17 illustrates exemplary embodiments of the filter device (200), wherein the first filter housing (202) and the second filter housing (204) are arranged in series. Each of the first and second filter housings of FIGS. 17a to 17c may be combined with each other. For example, and for all devices described herein, the first and second filter housings (202 and 204) may be detachably connected.
[0210] FIG. 17a illustrates a first filter housing (202), wherein the first filter housing (202) is partially covered with the first filter medium (203).
[0211] For example and for all embodiments, the first filter housing (203) can be gas-tight at the area of contact with the first filter medium (203) in order to move substantially all gas from the first filter housing (202) to the second filter housing (204).
[0212] The gas exits the first filter housing (202) via an opening (206) which may optionally also comprise a third filter medium as described herein which may, e.g., additionally straighten the gas flow.
[0213] As for all devices disclosed herein, a gas moving device may be positioned at the air inlet of the first filter housing (e.g. where the arrow shows entry of the gas into the device in FIG. 17a) or within the first filter housing (202).
[0214] For example, the first filter housing (202), i.e. the cavity (201) of all embodiments may be shaped or may comprise means for directing the gas flow towards the first filter medium (203) in order to ensure that polar liquids come into contact with the first filter medium (203) and are, e.g., absorbed thereon or therein.
[0215] The second filter housing (204) may comprise the second filter medium (205) at the site of gas exit, e.g. so that a cavity (207) is formed in between the fist filter housing gas exit and the second filter medium (205), wherein the volume of the cavity (207) and/or the surface area of the second filter medium may be adjusted depending on the required gas velocity/velocities.
[0216] FIG. 17b shows an alternative embodiment for the second filter housing (204), wherein the second filter medium (205) partially forms the second filter housing (204). The second filter housing (204) for any embodiment disclosed herein may also comprise the second filter medium (205) as a honeycomb structure. For example, the cavity (207) within the second filter housing (204) may be substantially completely filled with the second filter medium (205), for example in the form of a honeycomb cell filter with alternately closed cell openings (see, e.g. U.S. Pat. No. 4,276,071 A). The gas may then exit the second filter housing (204) on the housing side opposite to the site of gas entry (see, e.g. FIG. 17a) or through the sides of the second filter housing (see, e.g. FIG. 17b).
[0217] FIG. 17c illustrates a first filter housing, wherein the first filter medium (203) at least partially covers the first filter housing (202) on the side of the cavity (201). The first filter housing (203) can be gas-tight at the area of contact with the first filter medium (203) in order to move substantially all gas from the first filter housing (202) to the second filter housing (204).
[0218] A gas moving device (208), e.g. a radial blower, moves the gas and creates a rotational spin (circling arrows) within the first filter housing (202). For example, the shape of the gas moving device (208) may constitute flow-directing means which introduce and/or increase a rotational spin or turbulent flow of the gas within the first filter housing, for example also independent of the type of the gas moving device.
[0219] FIG. 18 illustrates an alternative filter device (200) according to the present invention. The second filter medium (205) is positioned in the center of the device (200). The second filter medium (205) may form the second filter housing (104) or an additional housing may be used. The first filter housing (202) is defined by the circumference of the second filter medium or housing (205, 204) and an outer hull. A gas enters the first filter housing (202) (see arrows) and passes through the first filter medium (203) before entering the second filter (205) or housing (204), e.g. through apertures (229) in the housing. The second filter medium (205) may be of a cell filter-type in which the gas is forced to cross the filter walls from one to another channel (230) before exiting the filter and filter device (200). The filter device illustrated in FIG. 18 may be of a tubular shape, e.g. in which the first filter medium (203) has a ring form and is circumferentially positioned around the second filter medium (205), wherein the gas flows through the first filter medium (203) in a substantially radial direction, and through the second filter medium (205) in a substantially axial direction, which allows for a very compact shape of the filter device (e.g. for use in airplanes, buses, cars or trains). Alternatively, the filter device (200) may be of a planar form comprising two or more discrete first filter elements (203).
Example 1: Experimental Validation of a System According to the Present Invention
[0220] A system according to the present invention was installed in a closed room as depicted in FIG. 9. The room had 60 m.sup.2 and a volume of 200 m.sup.3 with 11 desks distributed according to FIG. 9. The room also featured a water/air heat exchanger of the building heating system on the side walls. A filter device with the following features and properties was used: ceramic cell filter, diameter of 300 mm, 200 cells per inch.sup.2, pressure loss of 600 Pa at an air passage of 800 m.sup.3/h, degree of filtration for particles between 10-500 nm diameter: >99.9%, half-radial blower with a capacity of 800 m.sup.3/h, fresh air admittance to the filter at 80 m.sup.3/h. The air outlets were in the form of 2 tubes (see FIG. 9) with a length of 500 cm and a flow cross section of 100 cm.sup.2. The air outlets (tubes) comprised, i.e. were covered with, a porous membrane made from cotton cloth (150 g/m.sup.2) and a linen binding (50-500 μm porosity) through which the filtered air was admitted into the room. The air outlets were positioned essentially on the ground of the room on three sides of the room (analogous to a skirting board). The average velocity of the filtered air exiting the air outlets was set at 0.08 m/s. The air inlets were cone-shaped with a diameter of 100 cm at an angle of 90°. The coned openings of the air inlets were positioned about 1 m above the heads of people when sitting in the room. The average air velocity within the tubing connected to the air inlets was set to about 1.2 to 2 m/s which resulted in an average air velocity at the air inlets (at the lower edge of the cone) of about 0.05 to 0.2 m/s. To simulate an aerosol source (e.g. a source of contamination, e.g. viral particles emitted from a person), a nebulizer emitting a 3% NaCl-solution was used. The particle size of the dried solution was 20-25 nm. The nebulizer was positioned on a table in the room at the height of a person's face. A mobile sensor S1 (Partector, naneos particle solutions GmbH, Windisch, Switzerland) was used for detecting ultrafine particles (particles between 10 and 500 nm). On each of the tables a sensor S2 (Sensirion, Stäfa, Switzerland) was positioned to measure visible particles (measuring particles larger than 300 nm by laser diffraction). The particle concentrations and particle sizes at all tables and at the air inlets and outlets in the room were recorded simultaneously at 1 Hz. The pressures before and after the filter were measured and the air throughput was found to be proportional to the pressure loss with a laminar flow across the filter walls at 1-3 cm/s. The CO.sub.2 concentrations were measured and the substantially vertical laminar flow from the ground to the air inlets was confirmed by fume movements (Draeger-Tubes with H.sub.2SO.sub.4).
Example 2 Results with the Set-Up of Example 1
[0221] All measurements were conducted with all tables occupied by people and at a ventilation power of 60% and without any people in the room with a ventilation power of 100%.
Example 2a: Lateral Cross Contamination at 60% Ventilation Power and Full Occupancy
[0222] Lateral cross contamination is used as a model for infection. All tables were occupied by persons. The initial visible particle (larger than 300 nm) concentration in the room was set at 100-200 particles/cc at the onset of the experiment (verified by sensor S2) and the initial ultrafine particle (size between 10 and 500 nm) concentration was set at 2000 particles/cc (verified by sensor S1). The nebulizer was set to emit an average of about 500′000 ultrafine particles/cc (verified by sensor S1) at the perimeter of the cloud with peak particle concentrations of 5 mio/cc. The S2 sensors fixed on the tables to the right and left of the nebulizer detected 5000-6000 visible particles larger than 300 nm per cc at the same time at 0.6 m distance from the nebulizer while the S1 sensor detected up to 50′000 ultrafine particles/cc. The average visible particle concentration detected at those S2 sensors further away than the S2 sensors left and right of the nebulizer stabilized at about 100-1000 particles/cc after 20 minutes, while the ultrafine particle concentration detected with the S1 sensor stabilized at around 10′000 particles/cc. In conclusion, the system reduced the particle load in direct proximity to the source (nebulizer) by >95% and within the whole room by >98%. Example 2b: lateral cross contamination at 100% ventilation power at zero occupancy
[0223] Example 2a was repeated without any persons at the tables or in the room and at 100% ventilation power. The same results were obtained compared to Example 2a. In other words, the lack of thermal radiation from persons to support the essentially laminar flow in the room could be compensated by increasing ventilation power.
Example 2c: Decontamination at 60% Ventilation Power with Moving Persons
[0224] Example 2a was repeated but the persons previously seated at their tables continuously and quickly moved/walked within the room. Instead of the nebulizer, an E-cigarette was used to introduce a particle concentration of about 5000 particles/cc measured by sensor S2 (visible particles, >300 nm). After about 5 min at 60% ventilation power, the particle concentration was reduced by 50% as detected by all S2 sensors on 10 tables in the room. After 15 mins, the particle concentration was reduced by 80% as detected by all sensors in the room.
Example 2d: Filter Efficiency
[0225] Filter efficiency was determined by measuring the ultrafine particle concentration in the air admitted through the air inlets with sensor S1 starting from 10′000 particles/cc in the room. No visible or UFP particles could be detected in the air admitted through the air inlets which indicates that less than 200 particles/cc were present in the filtered air (detection threshold of the sensor S1 (Partector device)).
