Filtration appartus utilising acoustic agglomeration in air to improve filtration efficiency

Abstract

A filtration apparatus 100 comprising a chamber 102, one or more air inlets (105, fig. 2), a speaker (106, fig. 2) which generates acoustic waves to increase agglomeration of the air within the chambe

Description

Air pollution is an umbrella term that refers to suspended solid, liquid, or gaseous matter that does not belong to the natural composition of air. The main types of pollutants are particulate matter, nitrous oxides, ozone, sulphur dioxide, and carbon monoxide. These are generated from a variety of human activities such as fuel combustion, agriculture, and construction. According to the World Health Organisation (WHO), air pollution is responsible for 6.7 million premature deaths globally, while 3.2 million of these deaths are directly tied to household exposure to air pollution. Air purifiers are used to filter air by removing pollutants. A commonly used filter is a high-efficiency particulate absorbing (HEPA) filter, which uses densely and randomly packed fibres to capture particulate matter. However, HEPA filters are unsustainable as they are not recyclable, meaning they often end up in landfill. Another type of filter is an activated carbon filter. Activated carbon filters utilise large surface areas to ensure a greater volume of gas passes therethrough. However, activated carbon filters can be of limited use as they are not effective when eliminating non-carbon chemicals (e.g. heavy metals, nitrates, fluoride, sodium, etc.). A further consideration to be taken into account when selecting a filter is the desired size for the captured pollutant particles. Filtration solutions that often focus on the removal of medium to large particles, like PM2.5 and PM 10, often decrease the natural rate of agglomeration, leading to a higher particle size distribution of finer particles, which are often the most dangerous. The present invention was derived with the foregoing issues in mind. Summary of Invention According to a first aspect of the invention, there is provided a filtration apparatus. The filtration apparatus may comprise a chamber. The filtration apparatus may comprise one or more inlets configured to enable movement of air into the chamber. The filtration apparatus may comprise a speaker. The filtration apparatus may comprise a filter. The speaker may be configured to generate acoustic waves to increase agglomeration of the air within the chamber. Using a speaker to produce acoustic waves increases the rate of agglomeration within the chamber. Agglomeration creates larger particles which are more easily stopped and captured by a filter. Therefore, using a speaker to increase agglomeration improves filtration efficiency and enables the use of a lower grade filter. The chamber may be cylindrical. The chamber may be configured to sustain a vortex therein. The one or more inlets may be positioned such that air passing through the inlets forms a vortex is formed within the chamber. Generating a vortex increases the amount of time that the air is within the chamber, thereby increasing the likelihood of collisions which cause agglomeration. Generating a vortex further increases agglomeration by introducing turbulence to the air within the chamber. The filtration apparatus may comprise a fan. The fan may be configured to convey air through the one or more inlets into the chamber. Using a fan may increase the rotational speed of a vortex within the chamber, which creates more turbulence and thus increases agglomeration. The filtration apparatus may comprise guide vanes. The guide vanes may be disposed within the chamber. The guide vanes may be configured to generate a vortex within the chamber. The one or more inlets may be elliptical openings in the chamber. The filtration apparatus may comprise one or more channels. Each channel may be connected to an inlet. Each channel may be a venturi channel. Each channel may be curved. Each channel may be curved about a longitudinal axis of the chamber. The channels may increase the rotational speed of the vortex within the chamber, thereby increasing the rate of agglomeration due to increased turbulence. The fan may comprise one or more fans. Each fan may be disposed in a channel. Each fan may be angled between 0° and 90° relative to the longitudinal axis of the chamber. Having angled fans ensures that the air within the chamber has a vertical component to its velocity, which ensures that the air reaches the filter. The speaker may be configured to generate low frequency acoustic waves. The speaker may be configured to generate high frequency acoustic waves. The speaker may be configured to generate low frequency and high frequency acoustic waves. The speaker may be configured to generate acoustic waves with a speaker pressure level between OdB and 145dB. The speaker may be configured to generate acoustic waves with a speaker pressure level between 35dB and 45dB. The speaker may be a sub-woofer. The filter may be formed from, or comprises, a non-woven material. The filter may be formed from, or comprise, melt-blown material. The filter may be formed from, or comprise, electro-spun material. The filter may be, or comprises, polypropylene. The filter may be, or comprises, melt-blown polypropylene. The filter may be laser engraved. According to a second aspect of the invention, there is provided a method for promoting agglomeration within a volume of air. The method may comprise generating a turbulence-increasing flow structure within the volume of air. The method may comprise providing a speaker. The method may comprise using the speaker to generate acoustic waves within the volume of air to promote acoustic agglomeration. The turbulence-increasing flow structure may be a vortex. The turbulence-increasing flow structure may be a plurality of vortices. According to a third aspect of the invention, there is provided a method of filtration. The method may comprise providing a chamber. The method my comprise generating a vortex within the chamber to promote turbulent agglomeration. The method may comprise providing a speaker. The method may comprise using the speaker to generate acoustic waves within the chamber to promote acoustic agglomeration. The method may comprise providing a filter through which air can exit the chamber. Optional features of any of the above aspects may be combined with the features of any other aspect, in any combination. For example, features described in connection with the filtration apparatus of the first aspect may have corresponding features definable with respect to the method of the second aspect or third asepct, and vice versa, and these embodiments are specifically envisaged. Features which are described in the context or separate aspects and embodiments of the invention may be used together and / or be interchangeable wherever possible. Similarly, where features are, for brevity, described in the context of a single embodiment, those features may also be provided separately or in any suitable sub-combination. Brief description of the drawings Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a side view of a filtration apparatus according to the present invention; Figure 2 shows an exploded perspective view of the filtration apparatus of Figure 1; Figures 3(a) and 3(b) show cross-sectional side views of the filtration apparatus of Figure 1 together with representations of airflow within the filtration apparatus; Figures 4(a) and 4(b) respectively show perspective and side views of part of another filtration apparatus according to the present invention; Figure 5 shows an exploded perspective view of the filtration apparatus of Figure 4; Figures 6(a) and 6(b) respectively show partially transparent perspective and side views of part of the filtration apparatus of Figure 4; Figures 7(a) and 7(b) respectively show perspective and side views of part of another filtration apparatus according to the present invention; Figure 8 shows an exploded perspective view of the filtration apparatus of Figure 7; Figures 9(a) and 9(b) show perspective views of the filtration apparatus of Figure 7 with the top cover on and off respectively; and Figure 10 shows a flow chart for a method for promoting agglomeration in accordance with the present invention. Detailed description Figure 1 shows a side view of a filtration apparatus 100. The filtration apparatus 100 comprises a chamber 102, a plurality of inlets (see Figure 2), a speaker (See Figure 2), a filter 108, and a plurality of fans 110. The chamber 102 is cylindrical and defines a longitudinal axis A. The chamber 102 can be made of any suitable rigid material. For example, the chamber 102 can be formed from, or comprise, plastic or metal. In other embodiments, the chamber 102 is not cylindrical. The chamber can have any shape, as long as it is partially enclosed. The chamber 102 must have a shape which defines an internal volume and in which turbulence-increasing flow structures (such as vortices) can form. The chamber 102 comprises a plurality of inlets through which air can travel into the chamber 102. The inlets are opening formed in a wall of the chamber. In some embodiments, the inlets are elliptical openings. Each inlet is connected to a channel 104 which extends away from the chamber 102. The channels 104 are venturi channels, meaning they have a decreasing cross-sectional area towards the chamber 102, so as to increase the velocity of air travelling through the channels 104 towards the chamber 102. The channels 104 are curved so as to ensure that air travelling through the channels 104 has a rotational component of velocity as it enters the chamber 102. In other embodiments, the channels 104 are not venturi channels. In other embodiments, the channels 104 are not curved. The channels 104 must enable the passage of air from outside the filtration apparatus 100 into the chamber 102 of the filtration apparatus 100. The chamber 102 is connected to a lower cone 112. The lower cone 112 is connected to an upper cone 114. The filter 108 is disposed between the lower and upper cones 112, 114. Air within the chamber 102 exits through the cones 112, 114. As such, air travels through the filter 108 as it exits the chamber 102. Each of the plurality of fans 110 is positioned within a channel 104. There is one fan 110 disposed in each channel 104. The fans 110 are configured to convey air through the channels 104 and through the inlets into the chamber 102. In other embodiments, fans 110 are not disposed in every channel 104. Each fan 110 is angled relative to the longitudinal axis (A) of the chamber 102. Each fan 110 is disposed at an angle which is greater than 0° and less than 90°. Each fan 110 is disposed at the same angle as every other fan 110. In alternative embodiments of the invention, a single fan 110 can be used instead of, or in addition to, the fans 110 disposed in each channel 104. The single fan 110 can be positioned at a base of the chamber 102 (beneath a speaker 106) and can be configured to convey air along the longitudinal axis of the chamber 102. The channels 104 and the fans 110 are configured to generate a vortex within the chamber 102, as explained below in relation to Figure 3. Figure 2 shows an exploded perspective view of the filtration apparatus 100 of Figure 1. For clarity, the channels 104 are not shown in Figure 2. Instead, the inlets 105 are visible. The chamber 102 comprises a central aperture 102-1. The speaker 106 is configured to fit within the central aperture 102-1, so as the prevent air exiting the chamber 102 through the aperture 102-1. The speaker 106 is configured to generate acoustic waves which travel into the chamber 102. The speaker is configured to generate low frequency acoustic waves. In some embodiments, the speaker is configured to generate acoustic waves with a frequency between 10Hz-15,000Hz. In some embodiments, the speaker is configured to generate acoustic waves with a frequency between 10Hz-600Hz. In some embodiments, the speaker is a woofer or subwoofer. In some embodiments, the speaker is configured to generate acoustic waves with a speaker pressure level (SPL) between 0-145 dB. In some embodiments, the speaker is configured to generate acoustic waves with a speaker pressure level (SPL) between 10-140 dB. In some embodiments, the speaker is configured to generate acoustic waves with a speaker pressure level between 35- 45dB. In some embodiments, the filtration apparatus comprises a secondary speaker. The secondary speaker can produce acoustic waves at an ultrasonic frequency with travel into the chamber 102. The filtration apparatus 100 comprises guide vanes 116. When assembled, the guide vanes 116 fit within the chamber 102. In other embodiments of the invention, for example, in the embodiments of Figures 4-6 and 7-9, there are no guide vanes. Figure 3a shows a cross-sectional side view of the filtration apparatus 100. The path followed by air as it enters and exits the chamber 102 is shown in Figure 3a. The combined effect of the venturi channels 104 with the fans 110 and the guide vanes 116 creates a vortex 101 within the chamber 102. More specifically, the shapes of the channels 104 ensure that the velocity of air entering the chamber 102 has both vertical (i.e., along the longitudinal axis A) and rotational components, so as to create a vortex in which air moves towards the filter 108. Figure 3b shows a side view heat map of air velocity within the filtration apparatus 100. Again, the vortex 101 is visible at the centre of the chamber 102. The velocity of the air within the filtration apparatus 100 is greatest at the edges of chamber 102. The vortex 101 causes turbulent agglomeration. This means that, as a result of the vortex 101, there is an increased rate of collisions between pollutants in the air within the chamber 102. This increased collision rate increases agglomeration (the process of particles colliding to form large structures). Additionally, the vortex 101 increases the amount of time that the air is within the chamber, which further increases the rate of agglomeration. The acoustic waves generated by speaker 108 provide acoustic agglomeration, which further increases the overall agglomeration. Acoustic agglomeration happens when particles of various sizes are exposed to acoustic waves. The particles respond to the acoustic waves based on their size and mass: smaller particles match the oscillation amplitude of the waves more closely than larger particles. If such differently sized particles are separated by a distance smaller or equal to the displacement amplitude of the acoustic waves, they will exhibit relative motion and collide as a result. The agglomeration (caused by both the turbulent and acoustic agglomeration) combines smaller particles to increase the average pollutant size. As a result, the particles passing through the filter 108 are more likely to be stopped / absorbed by the filter. As a result of the agglomeration, low-grade filters are suitable for use with the filtration apparatus. To provide optimum agglomeration, the filtration apparatus can comprise a sensor configured to measure / detect the particles within the chamber. This can be used to determine the typical / average size and mass of particles within the chamber. The speaker can be controlled based on the measured average particle size. For example, the speakers can be controlled to output acoustic waves with a specific frequency, or specific combination of frequencies, so as to provide maximum agglomeration for a given average particle sizc / mass. The filter 108 is formed from a fabric. In some embodiments, the filter 108 is formed from a non-woven fabric. For example, the filter can be formed from, or comprise, electro-spun or melt-blown materials. In some embodiments, the filter 108 is formed from melt-blown polypropylene. In alternative embodiments, the filter 108 is formed from a woven fabric. In alternative embodiments, the filter 108 is not formed from a fabric. In some embodiments, the surface of the filter 108 is engraved using a laser to create a plurality of ridges. The filter 108 can be laser engraved to increase the surface roughness of the filter 108. The filter 108 can be laser engraved using a greyscale colour block to enhance its particle capture capabilities. The engraving process is used to create or increase extreme surface roughness to allow more particles to be captured. The depth and width of the grooves formed by the laser engraving can be within the 2.5-100pm range. In some embodiments, the laser engraving is performed using a Trotec Speedy 360 laser cutter. In some embodiments, the laser engraving is performed with power at 15% and speed set at 100%. Figures 4(a) and (b) show perspective and side views respectively of part of an alternative filtration system 200 in which the chamber 202 is curved, thereby removing the need for separate cones. The filtration apparatus 200 comprises channels 204 which convey air into the chamber 202 through inlets 205. As with the filtration apparatus of Figure 1, there are a plurality of fans 210, wherein each fan 210 is positioned within a channel 204. A speaker 205 is positioned at the base of the chamber 202 Figure 5 shows a perspective exploded view of the filtration system 200. The filtration system 200 comprises a housing formed by a speaker cabin 220, a mesh 219,and a cover 218. The speaker cabin 220 is a box that comprises a central aperture in a top surface configured to receive the speaker 210. The box is hollow and enables the speaker 210 to function as intended by suppressing unwanted sounds. The mesh 219 comprises a plurality of apertures and enables the passage of air therethrough. The mesh 219 allows air to be drawn into the chamber 202 whilst providing a continuous surface shape for the housing. The mesh 219 is positioned on top of the speaker cabin and is connected to the cover 218. In alternative embodiments, the mesh may be replaced with a frame portion comprising openings. The cover 218 acts as a lid to protect components within the housing. The cover 218 comprises a central aperture configured to retain the filter 208. The housing ensures that air which enters through the mesh 219 exits through the filter 208. Figures 6(a) and 6(b) show transparent perspective and side views of the filtration apparatus 200 when assembled. The chamber 202, together with channels 204 and speaker 210 are housed within the housing, above the speaker cabin 220. The mesh 219 aligns with the channels 204 to ensure that air can pass through the channels 204 and inlets 205 into the chamber 202 unrestricted. Figures 7(a) and (b) respectively show perspective and side views of part of another alternative filtration apparatus 300. The filtration apparatus 300 comprises a chamber 302 comprising inlets 305 which are connected to channels 304. A fan 310 is disposed in each of the channels 305. A base 322 is connected to the bottom of the chamber 302. The base 322 configured to support the chamber 302 within a housing, as described below in relation to Figure 8. A speaker 310 is secured to the base 322 on an opposing side to the chamber 320. There is a central aperture in the base 322 to allow the passage of acoustic waves from the speaker 210 into the chamber 320. Figure 8 shows a perspective exploded view of the filtration system 300. The filtration system 300 comprises a housing formed from a speaker cabin 320, a mesh 319, and a cover 318. The speaker cabin 319 is similar to the speaker cabin 219 of the filtration apparatus 200. The speaker cabin 319 has an open top into which the base 322 is securable. The filtration system 300 comprises feet 324 which are connectable to a bottom of the speaker cabin 319. The chamber 302 and speaker 308 connect to the base 322 as shown in Figure 7 and are housing within the housing. When assembled, the mesh 319 is positioned above, and secured to, the speaker cabin 319, and surrounds the chamber 302 and the channels 304. The mesh 319 is a solid structure and comprises handles 321. The mesh 319 comprises a plurality of vertical apertures configured to enable the passage of air therethrough. The handles 321 enable the filtration apparatus 300 to be lifted and carried around by a user. The mesh 319 has an open top configured to receive the cover 318. The cover 318 has a central aperture configured to retain the filter 308 therein. Figures 9(a) and 9(b) show perspective views of the filtration apparatus 300 with the cover 318 secured and removed respectively. When assembled, air enters into the filtration apparatus 300 through the mesh 319, and then into the chamber 302 via the channels 304 and inlets 305. Air exits the chamber 302 through the filter 308 in the cover 318. The filtration apparatus 300 comprises a user interface 326 which enables a user to control the volume of the speaker 308. Filtration apparatus 200 and filtration apparatus 300 are configured to provide turbulent and acoustic agglomeration, as described for filtration apparatus 100. In each of the filtration apparatus 100, 200, 300 described herein, the speakers serve a dual purpose. As already described, the first function of the speaker is to provide low frequency acoustic waves to promote acoustic agglomeration. The second purpose is to function as a standard speaker (i c.. to play music, voice, or other sound). Each filtration apparatus may have two modes of operation: a speaker mode and a filtration mode. In a filtration mode, the speakers may simply provide low frequency vibrations to promote acoustic agglomeration without providing a sound for a user. In a filtration mode, the fans can be turned on to draw air into the filtration apparatus. In a speaker mode, the speaker can be connected to a user device (e.g., a smartphone, PC, or other device) to play music or any other desired audio media. In a speaker mode, the acoustic waves promote acoustic agglomeration whilst also serving as a conventional speaker. In a speaker mode, the fans can be turned off to enable a user to hear the acoustic waves generated by the speaker. Alternatively, the fans can be set to rotate at a reduced speed in order to produce less noise. Each filtration apparatus may also have a third mode. In a third mode, the speaker may play songs or sounds specifically designed to create acoustic waves which effectively increase agglomeration. The fans can be on or off in this third mode. The housings descried for each filtration apparatus described herein are not limiting for the invention and are provided for purposes of example only. In other embodiments, alternative housings can be used with any of the filtration systems described herein. Whilst the description above refers to a filtration apparatus, the invention more broadly relates to agglomeration effects produced by combining acoustic waves with a vortex. Figure 10 shows flowchart for a method 1000 of promoting agglomeration. The first step 1100 is to generate a turbulence-increasing structure. The turbulenceincreasing structure can be a vortex, a plurality of vortices, or any other flow structure which increases turbulence. This generating can be done using one or more fans together with angled inlets into a chamber, as described for the filtration apparatus above. Alternatively, any other conventional method for generating a vortex can be used. The second step 1200 is to then provide a speaker. For example, the speaker may be any of the speakers described above. Alternatively, any conventional speaker, such as woofers and subwoofers, can be used. The final step 1300 is to use the speaker to generate acoustic waves within the vortex. The acoustic waves can be generated by a speaker positioned beneath the vortex, as in the filtration apparatus described above, or the acoustic waves can be generated from a speaker at any other position relative to the vortex. The method 1000 can be used for filtration purposes, as in the filtration apparatus described herein, by further providing a filter to capture pollutant particles from the air following agglomeration. However, the method 1000 can also be used in a variety of other situations. For example, industrial plants (e.g., for metal / food processing) use or produce toxic byproducts (such as hydrogen sulphide). Powder-based neutralization agents are very good at neutralizing these toxic by-products due to the agent’s very high surface area and chemical properties. However, leveraging this high surface area and making the powder collide effectively with the toxic by-products is an issue. The method 1000 of providing acoustic and turbulent agglomeration can create an environment where the powder is suspended in a vortex and has an open space to collide and reach with the by-products. The vortex increases the exposure time, thereby increasing the effectiveness of the neutralizing powder. This way, the powder can be suspended so that all of its surface is exposed for contact. Meanwhile, the acoustic and turbulence agglomeration aspects help to enhance and accelerate the desired collisions. As a further example use case, during a fire, a lot of toxic compounds are generated either as a result of combustion or release of fibres like asbestos. Teams are usually instructed to spray water into the air so that these particles can get deposited to the ground before they spread further. However, this process is very inefficient as the rescue teams need to respond to the immediate fire threat and the area which they can spray with a hose is very limited. As such, devices such as the filtration apparatus described above can be used to remove pollutants whilst rescue teams perform other duties. From reading the present disclosure, other variations and modifications will be apparent to the skilled person. Such variations and modifications may involve equivalent and other features which are already known in the art of air filtration systems, and which may be used instead of, or in addition to, features already described herein. Although the appended claims are directed to particular combinations of features, it should be understood that the scope of the disclosure of the present invention also includes any novel feature or any novel combination of features disclosed herein either explicitly or implicitly or any generalisation thereof, whether or not it relates to the same invention as presently claimed in any claim and whether or not it mitigates any or all of the same technical problems as does the present invention. Features which are described in the context of separate embodiments may also be provided in combination in a single embodiment. Conversely, various features which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination. The applicant hereby gives notice that new claims may be formulated to such features and / or combinations of such features during the prosecution of the present application or of any further application derived therefrom. 5 For the sake of completeness, it is also stated that the term "comprising" does not exclude other elements or steps, the term "a" or "an" does not 5 exclude a plurality, a single processor or other unit may fulfil the functions of several means recited in the claims and any reference signs in the claims shall not be construed as limiting the scope of the claims. 10 06 01 25

Claims

1. A filtration apparatus, comprising:a chamber;5 one or more inlets configured to enable movement of air into the chamber;a speaker;a filter; andguide vanes disposed within the chamber;one or more venturi channels, each channel being connected to an inlet;10 one or more fans, each fan being disposed in a venturi channel and wherein eachfan is angled between 0° and 90° relative to the longitudinal axis of the chamber;wherein the combined effect of the venturi channels with the fans and the guide vanes creates a vortex within the chamber; andwherein the speaker is configured to generate acoustic waves to increase15 agglomeration of the air within the chamber.

2. The filtration apparatus of claim 1, further comprising a fan configured to convey air through the one or more inlets into the chamber;20 3. The filtration apparatus of any preceding claim, wherein the one or more inletsare openings in a wall of the chamber.

4. The filtration apparatus of any preceding claim, wherein the speaker is configured to generate low frequency acoustic waves.

255. The filtration apparatus of any preceding claim, wherein the speaker is a subwoofer.

6. The filtration apparatus of any preceding claim, Wherein the filter is formed 30 from, or comprises, a non-woven material.

7. The filtration apparatus of claim 6, wherein the filter is, or comprises, polypropylene.

8. The filtration apparatus of claim 7, wherein the filter is, or comprises, melt-blown polypropylene.

9. The filtration apparatus of any preceding claim, wherein the filter is laser5 engraved.

10. A method of filtration, comprising:providing a chamber, guide vanes disposed within the chamber, one or more venturi channels, and one or more fans;10 using the guide vanes, venturi channels and fans to generate a vortex within thechamber to promote turbulent agglomeration;providing a speaker;using the speaker to generate acoustic waves within the chamber to promote acoustic agglomeration; and15 providing a filter through which air can exit the chamber.LDCM

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