“APPARATUS AND METHOD FOR AGGLOMERATING PARTICULATE MATTER”

FIELD OF THE INVENTION

[0001] This invention relates generally to apparatus for agglomerating particulate matter, and a method for designing apparatus for agglomerating particulate matter, and in particular, for agglomerating particulate matter entrained in fluid such as vehicle exhaust.

BACKGROUND OF THE INVENTION

[0002] The two primary exhaust elements of a modern diesel engine are particulate matter (soot) and nitrogen oxides. The petrol or gasoline engine similarly emits harmful exhaust elements including hydrocarbons, nitrous oxide and particulate matter. Airborne particles significantly reduce air quality and are thus one of the targets of new European vehicle emission standards; Euro 6 Emission standards. These emissions standards define the limits for exhaust emissions of new vehicles sold in Europe, including defining limitations on both particulate matter and number of particles emitted per kilometer.

[0003] Existing emission-treatment technologies can broadly be grouped into ‘exhaust after-treatment systems’ and‘in-engine’ categories. Existing retrofit options include diesel particulate filters and diesel oxidation catalysts, both of which fit onto engines like mufflers. A problem with the mechanical mesh-type filters that are often used to remove DPM is that they make restrictions against exhaust flow thus cannot efficiently filter the fine and ultrafine particles. While appearing cleaner, the exhaust fumes still contain large amounts of small DPM. A further problem with mechanical filters is that they become clogged and require replacement and/or cleaning at regular intervals. Advanced new in-engine technologies such as electronic controls, common-rail fuel injection, variable injection timing, improved combustion chamber configuration and turbo charging have made diesel engines cleaner. A number of these recent vehicle emission reduction technologies are cost prohibitive, thereby limiting their uptake by major automotive brands.

SUMMARY OF THE INVENTION

[0004] The object of the present invention is to substantially overcome, or at least ameliorate, one or more disadvantages of existing arrangement and/or provide a workable alternative.

[0005] In a first broad form, the present invention seeks to provide apparatus for agglomerating particulate matter entrained in a fluid, the apparatus including:

an inlet for receiving the fluid;

an outlet for releasing the fluid;

at least one a conduit in fluid communication with the inlet and the outlet;

at least one piezoelectric actuator provided in the at least one conduit; and,

at least one electrode in electrical communication with the piezoelectric actuator;

wherein in use, electrical energy is applied to the electrode to actuate the piezoelectric actuator, and thereby generate acoustic energy in the at least one conduit to at least partially agglomerate the particulate matter entrained in the fluid.

[0006] In one embodiment, the fluid includes vehicular exhaust.

[0007] In one embodiment, the piezoelectric actuator at least partially conforms to at least part of an inner surface of the conduit.

[0008] In one embodiment, the conduit includes any one of:

two or more piezoelectric actuators;

three or more piezoelectric actuators;

four or more piezoelectric actuators; and,

five or more piezoelectric actuators. [0009] In one embodiment, each conduit includes:

a first electrode in electrical communication with an outer surface of each of the at least two piezoelectric actuators; and,

a second electrode in electrical communication with an inner surface of each of the at least two piezoelectric actuators.

[0010] In one embodiment, the piezoelectric actuator conforms to an inner surface of the conduit.

[0011] In one embodiment, in the piezoelectric actuator is polarised in a transverse direction to a conduit axis.

[0012] In one embodiment, the piezoelectric actuator is radially polarised.

[0013] In one embodiment, the piezoelectric actuator is radially symmetric.

[0014] In one embodiment, in use the applied electrical energy actuates the piezoelectric actuator in accordance with an eigenfrequency of the conduit.

[0015] In one embodiment, the apparatus includes at least two conduits coupled together in series between the inlet and the outlet.

[0016] In one embodiment, in use the applied electrical energy actuates respective piezoelectric actuators of each of the conduits in accordance with respective eigenfrequencies of each of the at least two conduits.

[0017] In one embodiment, dimensions of the at least two conduits are different to thereby differ respective eigenfrequencies of each of the conduits.

[0018] In one embodiment, the respective eigenfrequencies of the conduits increase from inlet to outlet.

[0019] In one embodiment, an outer surface of the conduit conforms to an inner surface of a vehicular exhaust system.

[0020] In one embodiment, the conduit forms at least a portion of a vehicular exhaust system.

[0021] In one embodiment, the apparatus is operable at temperatures above at least one of: 100 degrees Celsius;

200 degrees Celsius; and,

250 degrees Celsius.

[0022] In one embodiment, the electrical energy is applied in accordance with at least one of a resonant frequency and an eigenfrequency of the piezoelectric actuator.

[0023] In one embodiment, the applied electrical energy is determined to substantially optimise a sound pressure level in the at least one conduit.

[0024] In one embodiment, the applied electrical energy selectively changes in accordance with at least one indicator at least partially indicative of acoustic energy in the conduit, to thereby selectively change a sound pressure level in the conduit.

[0025] In one embodiment, the apparatus includes an electronic processing device configured to control the electrical energy applied to the electrode.

[0026] In one embodiment, the electronic processing device is in electrical communication with an engine control unit.

[0027] In one embodiment, the electronic processing device is configured to: determine electrical energy to be applied to the piezoelectric actuator; generate control signals in accordance with the determined electrical energy; and,

control the electrodes in accordance with the control signals.

[0028] In one embodiment, the electronic processing device is further configured to:

determine at least one indicator, the indicator being at least partially indicative of acoustic energy in the conduit;

compare the indicator to a reference; and,

determine the electrical energy to be applied to the piezoelectric actuator based upon the results of the comparison.

[0029] In one embodiment, the indicator is indicative of at least one of:

acoustic energy of the conduit; revolutions per minute of an engine of a vehicle;

temperature within the chamber;

fuel consumption of a vehicle; and,

flow rate of the fluid.

[0030] A In one embodiment, the apparatus includes a microphone for sensing sound pressure levels of at least part of the conduit, the microphone being in operable communication with the electronic processing device.

[0031] In one embodiment, the piezoelectric actuator substantially forms the conduit.

[0032] In one embodiment, a housing defines an outer surface of the conduit.

[0033] In one embodiment, the housing is substantially composed of metal.

[0034] In one embodiment, the conduit is configured to dissipate heat from the piezoelectric actuator.

[0035] In one embodiment, the piezoelectric actuator includes piezoelectric ceramic.

[0036] In one embodiment, at least part of at least one of an inner surface and an outer surface of the piezoelectric actuator is provided with insulation.

[0037] In one embodiment, the insulation is adhered to at least part of the inner surface of the piezoelectric actuator.

[0038] In one embodiment, the piezoelectric actuator is shaped to

substantially conform to an inner surface of at least part of a vehicular exhaust system.

[0039] In one embodiment, the piezoelectric actuator defines a cross-section shaped at least one of: substantially circular; and, substantially oval.

[0040] In one embodiment, the apparatus includes at least one flow laminator for at least partially guiding the fluid in the conduit toward a laminar flow.

[0041] In one embodiment, each conduit includes a flow laminator. [0042] Apparatus according to any one of the claims 1 to 37, wherein the particulate matter includes diesel particulate matter.

[0043] In one embodiment, the particulate matter includes colloidal particulates.

[0044] In one embodiment, the fluid is a liquid.

[0045] In one embodiment, the at least one eigenfrequency is greater than 10kHz.

[0046] In one embodiment, the at least one eigenfrequency is greater than 20kHz.

[0047] In a second broad form, the present invention seeks to provide a method for designing an apparatus for agglomerating particulate matter entrained in a fluid, the method including in an electronic processing device:

determining at least one conduit parameter indicative of a characteristic of the conduit;

generating a model of the conduit using the at least one conduit parameter;

determining at least one eigenfrequency of the conduit using the model;

optimising a sound pressure level using the at least one eigenfrequency and the model; and,

generating at least one manufacturing parameter in accordance with the optimisation.

[0048] In one embodiment, the method includes determining at least one manufacturing constraint, and modelling the conduit using the at least one manufacturing constraint.

[0049] In one embodiment, the manufacturing constraint includes at least one of:

a thickness of the piezoelectric actuator;

a length of the piezoelectric actuator; and,

a shape of the piezoelectric actuator. [0050] In one embodiment, the method includes:

generating a mesh indicative of the conduit; and,

using finite element analysis to calculate the at least one eigenfrequency of the conduit using the mesh; and,

optimise a sound pressure level using the mesh and the at least one eigenfrequency.

[0051] In one embodiment, the at least one conduit parameter includes any one or more of:

a residence time;

a flowrate of the fluid;

a shape of the conduit; and,

at least one of an inner diameter and an outer diameter of the conduit and/or piezoelectric actuator.

[0052] In one embodiment, the at least one manufacturing parameter includes:

at least one of an inner diameter and an outer of the conduit and/or piezoelectric actuator;

a length of the conduit;

a number of piezoelectric actuators in a respective conduit; and, a number of conduits.

BRIEF DESCRIPTION OF THE DRAWINGS

[0053] An example of the present invention will now be described with reference to the accompanying drawings, in which:

[0054] Figure 1A is a perspective view of a schematic diagram of an example of an apparatus for agglomerating particulate matter entrained in a fluid;

[0055] Figure 1 B is a side view of the example of Figure 1 A;

[0056] Figure 1C is a cross-sectional view of the example of Figure 1A;

[0057] Figure 1 D is a front view of the example of Figure 1 A; [0058] Figure 1 E is a close-up cross-sectional perspective view of a portion of the example of Figure 1A;

[0059] Figure 1 F is a close-up cross-sectional perspective view of a further portion of the example of Figure 1A;

[0060] Figure 2 is a flow diagram of an example of a method for

agglomerating particulate matter entrained in a fluid;

[0061] Figure 3 is a schematic diagram of an example of a controller for use with an apparatus for agglomerating particulate matter entrained in a fluid;

[0062] Figure 4 is a schematic diagram of a further example of a controller for use with an apparatus for agglomerating particulate matter entrained in a fluid;

[0063] Figure 5A is a perspective view of a schematic diagram of an example of an apparatus for agglomerating particulate matter entrained in a fluid;

[0064] Figure 5B is a side view of the example of Figure 5A;

[0065] Figure 5C is a front view of the example of Figure 5A;

[0066] Figure 5D is a cross-sectional view of the example of Figure 5A;

[0067] Figure 6A is an image of an example experiment including an apparatus for agglomerating particulate matter;

[0068] Figure 6B is an image of an example measuring device for validating the experiment of Figure 6A;

[0069] Figure 6C is a schematic of an example of the experimental set-up of Figure 6A;

[0070] Figure 6D is a graphical representation of results of the experiment of Figure 6A;

[0071] Figure 7A is an image of a further example experiment including an apparatus for agglomerating particulate matter;

[0072] Figure 7B is a schematic of an example of the experimental set-up of Figure 7A;

[0073] Figure 7C is a graphical representation of results of the experiment of Figure 7A;

[0074] Figure 8 is a flow diagram of an example of a method for designing an apparatus for agglomerating particulate matter entrained in a fluid; and, [0075] Figure 9 is a flow diagram of a further example of a method for designing an apparatus for agglomerating particulate matter entrained in a fluid.

DETAILED DESCRIPTION OF THE INVENTION

[0076] An apparatus for agglomerating particulate matter entrained in a fluid will now be described with reference to Figures 1 A to 1 D.

[0077] In this example, the apparatus 100 includes an inlet 101 for receiving the fluid FIN, and an outlet 102 for releasing the fluid FOUT. The apparatus 100 further includes four conduits 110, 120, 130, 140 in fluid communication with the inlet 101 and outlet 102. While in this example four conduits 110, 120, 130, 140 are shown, in other examples any suitable number of conduits may be used including one or more conduits 110, 120, 130, 140 and this will be described further below. In addition, the apparatus 100 includes a piezoelectric actuator 110.3 provided in each of the conduits 110, 120, 130, 140, and at least one electrode in electrical communication with the piezoelectric actuators 110.3.

[0078] In use, electrical energy is applied to the electrode to actuate the piezoelectric actuators 110.3, to thereby generate acoustic energy in the conduits 110, 120, 130, 140 to at least partially agglomerate the particulate matter entrained in the fluid FIN.

[0079] Accordingly, the apparatus 100 enables the agglomeration of particulate matter entrained in a fluid, and in some examples, micron and sub-micron particulate matter. This can reduce the need for highly specified, and sub-micron pore mechanical filters or inertial separators. Moreover, in some examples, such as where the fluid includes vehicular exhaust, the apparatus 100 can reduce the number of particles released into the environment from a vehicle exhaust system, thus increasing vehicle emission standard compliance and decreasing environmental impact.

[0080] Additionally, as the apparatus 100 reduces the requirement for sub micron porous filters, this can ensure vehicle engine operating temperatures and back pressure remain within reasonable limits - in turn reducing nitrous oxide emissions. Furthermore, larger-pored mechanical filters may be used for the resulting particulate agglomerations, where such filters may be more cost effective.

[0081] The apparatus is also operable at low energy, which is particularly beneficial for many applications. In some examples, the apparatus 100 is operable using a low power energy source, such as a 12-Volt battery. This is particularly beneficial in, for example, a vehicle which typically contains a 12-Volt battery. Thus, typically the apparatus 100 may be operated in a vehicle using the vehicle’s existing battery, without the need for additional energy or power sources.

[0082] A number of further features will now be described.

[0083] In the example shown, each conduit 110, 120, 130, 140 includes a housing 110.1 formed of a suitable material, such as metal, steel, or the like. This can be advantageous in providing protection and mitigating damage to the conduit. However, in other examples the piezoelectric actuators 110.3 may instead form part or substantially all of an external surface of the conduit 110, 120, 130, 140. While the outer housing 110.1 in this example is cylindrical, in other examples it may include any suitable shape, for example, with an oval cross-section or the like. In some instances, it may be desirable for the housing 110.1 to conform to, or replace, at least a portion of a larger system. For example, the housing 110.1 and/or conduits 110, 120, 130, 140 may conform to, or replace, at least a portion of a vehicle exhaust system such as an inner or outer surface, and thus is appropriately shaped for this purpose.

[0084] Also, in this example, each conduit 110, 120, 130, 140 includes one or more piezoelectric actuators 110.3. The piezoelectric actuators 110.3 may include any suitable piezoelectric material capable of actuating according to the application of the apparatus. For example, typically, the piezoelectric actuators 110.3 include piezoelectric ceramic. The type of piezoelectric ceramic may be selected according to environmental or fluid characteristics, such as expected temperature exposure, or the like. For example, in the preferred embodiment a piezoelectric ceramic with a high Tc (Curie Temperature), for example above 320 degrees Celsius, may be used, such as Bismuth Titanate, Modified Lead Metaniobate, Modified Lead Zirconate Titanate (PZT) and/or PT types. [0085] In this instance, the piezoelectric actuators 110.3 conforms to an inner surface of the respective conduit 110, 120, 130, 140. Also, in this example, the piezoelectric actuators 110.3 are also substantially cylindrical. However, it will be appreciated that in other examples the actuators 110.3 may be any appropriate shape, including being substantially radially symmetric, having a substantially oval cross-section, or otherwise conforming to a shape of a larger system such as a vehicle exhaust system, or the like. Additionally or alternatively, the piezoelectric actuators 110.3 may be discontinuous about a cross-section of the conduit.

[0086] In another embodiment the piezoelectric actuators 110.3 may be integrally formed in each conduit 110, 120, 130, 140 and/or may be formed by coupling multiple piezoelectric actuators 110.3 together. In the preferred

embodiment shown in Figure 1 E, each conduit 110, 120, 130, 140 includes five piezoelectric 110.3, 110.31 , 110.32, 110.33, 110.34 actuators operably coupled in series along the conduit axis. However, in other examples, any suitable number of piezoelectric actuators 110.3 may be included in a conduit 110, 120, 130, 140, including one, two, three, four, five, or more piezoelectric actuators operably coupled in series along the conduit axis. This will be described in further detail below.

[0087] In this example, the piezoelectric actuators 110.3 are radially polarized. This is advantageous as it ensures the sound waves are propagated inwardly and within the conduit 110, 120, 130, 140. However, in other examples, the piezoelectric actuators 110.3 may be polarized in a transverse direction to a conduit axis, or axis defined by the conduit, or in any other suitable manner.

[0088] Any suitable dimension of conduit 110, 120, 130, 140 and/or piezoelectric actuator 110.3 may be used according to the application. Indeed, an example method for designing an apparatus is discussed further below. As an illustrative example, in Figures 1A to 1 D the conduits are coupled in series and increase in size from inlet to outlet. Accordingly, the eigenfrequencies of the conduits decrease from inlet to outlet. This can be advantageous in agglomerating particulate matter in a staged approach from inlet to outlet, by agglomerating progressively larger particulate matter as the fluid passes through the apparatus 100. [0089] In one specific example, the conduit 110 includes a piezoelectric ceramic tube 110.3 including an inner diameter of about 44 mm, and outer diameter of about 48 mm, and a length of 150 mm. The tube is composed of five

piezoelectric ceramic tube segments of 30 mm each. The tube 110.3 is radially polarized, and substantially composed of material PSnN-5. The adjacent conduit 120 includes a piezoelectric ceramic tube including an inner diameter of about 48 mm, and outer diameter of about 52 mm, and a length of 150 mm. The tube is composed of five piezoelectric ceramic tube segments of 30 mm each. The tube is radially polarized, and substantially composed of material PSnN-5.

[0090] The conduit 130 adjacent to the above includes a piezoelectric ceramic tube including an inner diameter of about 52 mm, and outer diameter of about 56 mm, and a length of 150 mm. The tube is composed of five piezoelectric ceramic tube segments of 30 mm each. The tube is radially polarized, and substantially composed of material PSnN-5. The conduit 140 adjacent the outlet includes a piezoelectric ceramic tube including an inner diameter of about 56 mm, and outer diameter of about 60 mm, and a length of 150 mm. The tube is composed of five piezoelectric ceramic tube segments of 30 mm each. The tube is radially polarized, and substantially composed of material PSnN-5.

[0091] As discussed above, however, this is a specific examples of conduit 110, 120, 130, 140 dimensions, and is not essential.

[0092] Where more than one piezoelectric actuator 110.3 is included in a single conduit 110, 120, 130, 140, the electrode is typically in electrical

communication with all of the piezoelectric actuators 110.3 in that conduit 110, 120, 130, 140. This is particularly beneficial in ensuring that multiple actuators 110.3 in a single conduit vibrate similarly at the same frequency, thus mitigating the risk that respective frequencies of actuators 110.3 within the same conduit interfere with the sound pressure level generated in that conduit 110.3. In the preferred embodiment, each conduit 110, 120, 130, 140 includes two electrodes. A first electrode is in electrical communication with the outer surface of each of the piezoelectric actuators 110.3 in the conduit, and a second electrode is in electrical communication with the inner surface of each of the piezoelectric actuators 110.3. For example, the electrodes may be soldered to the inner and outer surfaces of the actuators 110.3, respectively.

[0093] In the preferred embodiment, inner faces of piezoelectric ceramics 110.3 of each conduit are electrically connected to + and outer faces are electrically connected to -, however this is not essential.

[0094] In some examples, an inner and/or an outer surface of the piezoelectric actuators 110.3 is substantially coated with an at least partially conductive material. For example, in some instances the inner and/or outer surface is coated with metal such as nickel alloys or chrome alloys, in order to increase conductivity among respective surfaces of one or more piezoelectric actuators within a single conduit. However, this feature is not essential.

[0095] The conduits 110, 120, 130, 140 of this example include inner insulation 110.4 and outer insulation 110.2. However, in other examples none, one or more of the inner and outer insulation 110.4, 110.2 may be included. Beneficially the insulation can dissipate heat from the piezoelectric actuators 110.3 in use, and can also dampen vibration of the actuators against adjacent components such as against the housing 110.1. The insulation may be formed of any suitable material according to the application. For example, in high temperature applications, such as in relation to vehicle exhaust systems, suitable insulation may include Superwool HT paper, or the like.

[0096] In some examples, the insulation may be at least partially adhered to an inner and/or outer surface of the piezoelectric actuator 110.3. This can be beneficial in ensuring the insulation remains in-situ, and dampening and heat dissipation functions are maintained. Any suitable adhesive may be used according to the application. For example, in vehicle exhaust systems, the preferred embodiment includes adhering the insulation using an adhesive referred to under the trade name ThermGrip.

[0097] In some examples it is advantageous to at least partially coat an inner surface of the inner insulation 110.4 of the conduit. As this surface of the insulation will be exposed to fluid flow, it can be beneficial to at least partially protect the insulation from the fluid and/or to minimize any influence the insulation has on flow characteristics of the fluid. Accordingly, in the preferred embodiment for use in vehicle exhaust and/or with exhaust emissions, an inner surface of the inner insulation 110.4 is coated with a product referred to under the trade name Superwool Hardener.

[0098] In some examples, piezoelectric actuators 110.3 of respective adjacent conduits 110, 120, 130, 140 are conductively and/or vibrationally isolated. This can ensure that the actuators do not interfere with the operation of adjacent conduits 110, 120, 130, 140 and/or that conduits are operable at different frequencies without substantial interference. This may be achieved in any suitable manner, as will be discussed below.

[0099] Also, in this example, the apparatus 100 includes five flow laminators

110.6, 120.6, 130.6, 140.6, 150.6. In particular, the flow laminators 110.6, 120.6,

130.6, 140.6, 150.6 in this example are located substantially at a boundary between adjacent conduits 110, 120, 130, 140. As shown in Figure 1 E and 1 F, in this example the flow laminators are interleaved between the adjacent piezoelectric actuator 110.3 of respective conduits 110, 120, 130, 140. Thus, the flow laminators

110.6, 120.6, 130.6, 140.6, 150.6 can also provide insulation between actuators 110.3 of respective conduits, which can be beneficial in electrically and/or vibrationally isolating actuators 110.3 such that they are operable at different frequencies. However, it will be appreciated that any suitable arrangement for including a flow laminator may be used.

[0100] The flow laminators 110.6, 120.6, 130.6, 140.6, 150.6 substantially guide the fluid though the apparatus, and in this example at least partially temper turbulent flow to encourage higher velocity, straight fluid flow. While any suitable form of flow laminator 110.6, 120.6, 130.6, 140.6, 150.6 may be used, in this example the flow laminators 110.6, 120.6, 130.6, 140.6, 150.6 are composed of a porous ceramic. In addition, a perimeter 110.5 of the flow laminator 110.6, 120.6,

130.6, 140.6, 150.6 which contacts the insulator and/or piezoelectric actuator 110.3 is blinded, for example, cavities in the porous media at this perimeter are

substantially filled and/or covered (e.g. with casketing tape or the like). This acts to prevent fluid flow at these perimeters, thus reducing the risk of damage to the insulation and/or actuators 110.3. The axial length of the flow laminators may be any suitable length. In the preferred embodiment, the flow laminators 110.6, 120.6, 130.6, 140.6, 150.6 are about 150 mm in axial length.

[0101] While this example shows five flow laminators 110.6, this feature is optional, and in other examples the apparatus may include zero, one, or any suitable number of flow laminators 110.6.

[0102] In some examples, the apparatus 100 may include one or more filters, for example, mechanical filters. These filters may be used to separate larger or agglomerated particles from the fluid, for example, before the fluid is released from the outlet. The agglomeration process can thus aid in lowering the concentration of smaller particles, allowing a larger pored mechanical filter to be used to filter large or agglomerated particulate matter. Larger pored filters can be advantageous as they may be more cost effective. In addition, in some applications such as vehicle exhaust, the presence of smaller pore, or compact filters can increase pressure in the engine leading to higher operation temperatures and higher concentrations of emitted nitrous oxide. Thus, by using larger pore filters with less compaction, the environmental impact of nitrous oxide can be reduced.

[0103] In use, typically the applied electrical energy actuates the piezoelectric actuator 110.3 in accordance with an eigenfrequency of the conduit.

Eigenfrequencies of a conduit can be influenced by the dimensions of the conduit, piezoelectric actuator 110.3 and the like. In particular, actuating in accordance with the eigenfrequency can maximise the sound pressure level, thus ensuring the optimal sound pressure level is generated at low power, or via an efficient use of power. In the example of multiple conduits, such as in relation to Figures 1A to 1 D, the applied electrical energy actuates respective piezoelectric actuators 110.3 of each of the conduits 110, 120, 130, 140 in accordance with respective

eigenfrequencies of each of the conduits 110, 120, 130, 140. In this regard, dimensions of the conduits may be different to thereby differ respective

eigenfrequencies of each of the conduits. [0104] In some examples, the eigenfrequency is greater than 10kHz, and/or greater than 20kHz.

[0105] Typically, the respective eigenfrequencies of the conduits 110, 120,

130, 140 increase from inlet to outlet. This can be beneficial in ensuring that agglomeration is staged from the smallest to largest particles across multiple conduits 110, 120, 130, 140. However, as discussed above this is not essential.

[0106] In some examples, the apparatus is operable at temperatures of above any one or more of 100, 200, 250 or more degrees Celsius.

[0107] In some instances, the electrical energy is applied in accordance with a resonant frequency of the piezoelectric actuator.

[0108] Additionally or alternatively, the electrical energy is applied to substantially optimise a sound pressure level in the conduit(s) 110, 120, 130, 140. Indeed, in the preferred embodiment, the applied electrical energy selectively changes in accordance with one or more indicators that are at least partially indicative of acoustic energy in the conduit, to order to thereby selectively change a sound pressure level in the conduit. This type of feedback can be advantageous in ensure the apparatus 100 continues to agglomerate at a desired level, as

characteristics of a system which change in use can affect resonant frequencies and sound pressure levels. In a vehicle exhaust system, for example, temperature, exhaust fluid flow, revolutions per minute (RPM), engine pressure, and the like can influence the sound pressure level in the conduits 110, 120, 130, 140.

[0109] In some examples, the apparatus 100 includes an electronic processing device configured to control the electrical energy applied to the electrode. Any suitable electronic processing device may be used, and this is discussed in more detail below. Optionally, the electronic processing device may be in

communication with an engine control unit, for example, of a vehicle.

[0110] In some instances, the electronic processing device may optionally be configured to perform a series of steps, such as those shown in Figure 2. In this example, at step 200, the electronic processing device is configured to determine electrical energy to be applied to the piezoelectric actuator. This may be achieved in any suitable manner, including accessing a store, such accessing a value stored in a memory store, look-up table or the like, via operator input, using computational modelling such as described in more detail below. A predetermined value may be been calculated in any suitable manner, including trial and experimentation, or the like.

[0111] At step 210, the electronic processing device is configured to generate control signals in accordance with the determined electrical energy. Typically, this includes generating instructions, such as for interpretation by a waveform generator, however any suitable form of control signals may be generated.

[0112] At step 220 the processing device is configured to control the electrodes of the apparatus 100 in accordance with the control signals. As discussed above, this may include direct control or indirect control, for example, via a waveform generator, and the like, and this is discussed in more detail below.

[0113] The example of Figure 2 also includes further optional steps including at step 230 determining one or more indicators, the indicators being at least partially indicative of acoustic energy in the conduit. For example, indicators may include parameters indicative of acoustic energy of the conduit, temperature within a conduit, flow rate of the fluid and/or for a vehicle exhaust emission system in particular, revolutions per minute of an engine of the vehicle and fuel consumption of the vehicle. Accordingly, the indicators may be sensed using a transducer (such as a microphone for sound pressure level, pressure or temperature transducer, or the like) or using, for example, data received from an engine control unit (ECU).

[0114] Once one or more indicators are determined, at step 240 they are compared to a reference. While any suitable reference may be used, in some examples the reference includes a predetermined threshold, a previously measured indicator, a threshold obtained from a reference population, or the like. In this regard, the reference may be determined from a store, look-up table or the like, calculated or generated, or at least partially determined using operator input.

[0115] At step 250, processing device determines the electrical energy to be applied to the piezoelectric actuator 110.3 based upon the results of the comparison. For example, if an indicator falls below or exceeds a threshold, the energy applied to the actuator 110.3 may be increased or decreased in order to ensure the apparatus 100 operates as desired.

[0116] Moreover, steps 210 to 250 may, in some examples, be continuously repeated while the apparatus 100 is operable.

[0117] In the preferred embodiment, the apparatus 100 includes a microphone for sensing sound pressure levels, e.g. a peak of the sound pressure level, in the conduit 110, 120, 130, where the microphone being in operable communication with the electronic processing device. Thus, if the processing device detects that the sound pressure level falls below a predetermined threshold, the electrical energy applied to the piezoelectric actuators 110.3 is adjusted to shift the sound pressure level within desired limits. This will be discussed in further detail below.

[0118] In some examples, the particulate matter includes diesel particulate matter. Additionally or alternatively, the particulate matter includes colloidal particulates. The fluid describe in the examples herein may include a liquid, gas, aerosol or the like.

[0119] As discussed above, in some examples the apparatus 100 includes an electronic processing device 300. Figure 3 is a schematic diagram of an exemplary electronic processing device 300 according to some of the embodiments described herein. In some further examples, herein, the electronic processing device 300 described provides one example of a controller, and this will be discussed in more detail below.

[0120] The electronic processing device 300 performs, like functionality in accordance with the method disclosed above. The processing system 300 includes a processor 240, such as one or more commercially available Central Processing Units (CPUs) in the form of one-chip microprocessors or a multi-core processor, coupled to a communication device 310 configured to communicate via one or more communication networks to other devices, sensors and/or systems, such as sensors S (e.g. microphones, acoustic transducers, or the like), an engine control unit (ECU) of a vehicle, an apparatus for agglomerating particulate matter 100 as described in the embodiments herein, or the like.

[0121] The communication network may be of any appropriate form, such as wired or wireless networks, or bus(es), USB, the Internet and provides connectivity between the processing device 300 and the sensors S, ECU, apparatus 100, and other the processing systems. It will however be appreciated that this configuration is for the purpose of example only, and in practice the processing system 300 can communicate via any one or more appropriate mechanism, such as via wired or wireless connections, including, but not limited to mobile networks, private networks, such as an 802.11 network, the Internet, LANs, WANs, or the like, as well as via direct or point-to-point connections, such as Bluetooth, or the like.

[0122] Furthermore, in this example the electronic process device 300 is shown communicating directly with the apparatus 100 of any of the examples herein. However, it will be appreciated that this communication may be indirect, for example, via a waveform generator, voltage drive circuits, or the like, and this will be discussed further below. In addition, the processing system may communicate with sensors, or the ECU, indirectly for example via one or more analog-to-digital converters (ADC), or the like.

[0123] The processing system 300 may also include a local memory 350, such as RAM memory modules. The processing system 300 optionally further includes an input device 320 (e.g. a touchscreen, mouse and/or keyboard to enter content) and an output device 330 (e.g. a touchscreen, a computer monitor display, a LCD display). One of more of the components of the processing system 300 may be interconnected by a bus.

[0124] The processor 340 communicates with a storage device 360, which may comprise any appropriate information storage device, including combinations of magnetic storage devices (e.g. hard disk drive), optical storage devices, solid state drives, and/or semiconductor memory devices. In some embodiments, storage devices 360 may comprise a store such as a database system 380. For example, the store may store one or more references, thresholds, configuration data or the like. Additionally or alternatively, the processor 340 may communicate with an external or remote storage device R or processor to determine, for example, one or more references, thresholds, configuration data, or the like.

[0125] Furthermore, the storage device 360 may store program code or instructions 370 that may provide computer executable instructions in accordance with the processes herein. The processor 340 thus may perform the instructions of the program code 370 to thereby operate in accordance with any of the

embodiments described herein. In this regard, the program instructions 370 may be store in a compressed, uncompiled and/or encrypted format, and may include other program elements, such as an operating system, database management system, device drivers used by the processor 340 to interface with, for example, peripheral devices.

[0126] Accordingly, it will be appreciated that the processing system 300 may be formed from any suitable processing system, such as a suitably programmed computer system, PC, web server, network server, or the like. In some

embodiments, the processing system 300 includes a mobile device, such as a smartphone, tablet, or the like, where at least some of the functionality of the device is operated via an application (“App”).

[0127] However, in order examples, the processing system 300 is a standard processing system, such as a 32-bit or 64-bit Intel Architecture based processing system, which executes software applications stored on non-volatile (e.g., hard disk) storage, although this is not essential. However, it will also be understood that the processing systems 300 could be or could include any electronic processing device, such as a microprocessor, microchip processor, logic gate configuration, firmware optionally associated with implementing logic, such as an FPGA (Field

Programmable Gate Array), or any other electronic device, system or arrangement.

[0128] Whilst a single processing system 300 is shown in this example, it will be appreciated that functions may be split among multiple processing systems 300 in geographically separate locations, and in some examples may be performed by distributed networks of processing systems 300 and/or processing systems provided as part of a cloud-based architecture and/or environment. [0129] In any event, in the preferred embodiment, the processing system 300 includes a controller supporting the functions of described herein, including determining electrical energy to be applied to the at least one electrode, and generating control signals indicative of the electrical energy wherein the control signals are electrically communicated to the apparatus 100.

[0130] Whilst in this example, the sensors S including ECU are shown external to the electronic processing system 200, in some examples one of more of the sensors S may be included in the processing device 300 and/or the electronic processing system may form part of the ECU.

[0131] A further example of an electronic processing device will now be described with reference to Figure 4. This particular example is suitable for use in vehicles, for example, in order to control an apparatus for agglomerating particulate matter entrained in the vehicle’s exhaust emissions. Thus, the output 409 of the processing device 400 is most typically applied to one or more electrodes of the apparatus as described in any one of the examples herein.

[0132] In this example, the processing device 400, which in some examples may be referred to as an electronic control module, includes a microcontroller 420 which accepts input from sensors S and/or an engine control unit ECU, in order to obtain indications of temperature (for example, a temperature of the vehicle engine and/or a temperature of or within the apparatus 100), flow rate of fluid in the apparatus 100, fuel consumption of the vehicle engine, and/or revolutions per minute (RPM) of the vehicle engine. While any suitable microcontroller 420 may be used, in some examples the microcontroller 420 includes a proportional integral derivative (PID) controller, and more typically an Arduino microcontroller.

[0133] The processing device 420 includes an analog to digital converter (ADC) 401 , predetermined code 402 which is executed in order to generate control signals, and a serial input/output interface 403 for communicating the control signals with a waveform generator 404. Thus, the ADC 401 accepts the sensed indications from the sensors S and/or ECU, converts these to digital signals which are interpreted according to the code 402. As described above, the digital sensed indications are typically compared to predetermined thresholds in order to generate an indicator of the electrical energy frequency to be applied to piezoelectric ceramics of the apparatus. Once generated, this frequency indicator frequency is communicated to the waveform generated 404 via the serial interface.

[0134] The waveform generator 404 accordingly generates a waveform in accordance with the received indicator. Typically, the waveform generator generates a sinusoidal voltage drive waveform at a frequency indicated by the microcontroller 420, however any suitable periodic waveform may be generated such as a triangular waveform or the like. In the preferred embodiment the waveform generator includes an AD9850. In this example, the frequency of the waveform 405 is typically between 20 Hertz and 50 k Hertz. The generated waveform 405 passes through a low-pass filter (LPF) 406 to substantially reduce high-frequency noise, and an amplifier 407 regulated by a voltage regulator 408 up to 100 Volts. In the preferred embodiment the amplifier 407 includes an HD600/4, and the voltage regulator includes an inverter such as the INTPW300. The microcontroller 420, waveform generator 404, LPF, and amplifier 407 are powered using a 12 Volt power source 410, which in the preferred embodiment includes a conventional vehicle battery.

[0135] The resultant output of the electronic processing device 400 is a filter, amplified voltage drive waveform 409 which can be applied to one or more of the electrodes of the apparatus 100 for agglomerating particulate matter in the vehicle’s exhaust.

[0136] While a single waveform is generated in this example, it will be appreciated that in other examples the processing device 400 may generate multiple waveforms, for example, in order to apply different waveforms to electrodes in respective conduits of the apparatus 100.

[0137] Accordingly, in this example the waveform applied to electrodes of the apparatus 100 is dynamically adjusted according to sensed vehicle, operational and/or apparatus parameters. This is particularly beneficial as parameters such as fluid flow, temperature, RPMs, etc. can alter sound pressure levels generated within the apparatus 100 thus changing the agglomeration properties. In some examples, the microcontroller is in communication with an acoustic sensor, which senses signals indicative of the sound pressure level in the apparatus 100. Therefore, including a feedback mechanism to dynamically adjust the applied waveform ensures that the agglomeration process is continuously optimized.

[0138] Example: International Laboratory for Air Quality and Health (ILAQH) Test

[0139] An example of an experiment conducted in relation to an apparatus 600 for agglomerating particulate matter in a diesel engine exhaust, also referred to as an exhaust treatment module (ETM), will now be described with reference to Figures 6A to 6D.

[0140] In this example, the apparatus 600 includes a metal pipe which houses four stages coupled in series (also referred to, in this example, as four stages). An inlet of the ETM 600 is coupled to the exhaust emissions of the diesel engine, and an outlet of the ETM 600 is coupled to a validation module (Figure 6B) including dilution system DS and an environmental monitoring system EM, which in this example was an EMS500 MKII.

[0141] Each stage of the ETM includes five hollow piezoelectric ceramic cylinders coupled together along the length of the stage, the piezoelectric ceramic cylinders within a stage being the same diameter and defining a respective acoustic chamber for each stage. In addition, the diameter the piezoelectric ceramic cylinders of each of the four ETM stages increases from inlet to outlet, such that the first stage defines the smallest inner diameter and the fourth stage defines the largest inner diameter.

[0142] The piezoelectric ceramic cylinders of each stage of the ETM included common electrodes which were electrically coupled to the inner and outer surfaces of all of five respective the cylinders of each stage. This ensured that the

piezoelectric ceramics in each acoustic chamber vibrated in accordance with the same electrical energy applied by a common electrode. In use, driving voltage waveforms of different frequencies are initially applied to each acoustic chamber, according to determined eigenfrequencies characteristic of the respective acoustic chambers. [0143] Thus, during the experiment, exhaust emissions flowed into the inlet and through four acoustic chambers defined by each of the stages, and was released from the outlet.

[0144] The test vehicle engine used in this experiment included the following specifications:

[0145] The experimental set-up is shown in Figure 6C, and included the engine E, coupled to a dynamometer D which operated to sense parameters relating to power of the engine E. The controller C captured these parameters, including engine control unit (ECU) parameters, flow rates, temperature, speed, load, and gas analysis. Moreover, a pressure transducer PT and crank angle sensor CA, were employed to measure indicated parameters ID, for example, parameters indicative of pressure and the position of the engine’s crankshaft in relation to the piston. The engine E was also coupled to a compressor COM and turbocharger TC, and exhaust emissions EE were captured from an outlet of the turbocharger TC and guided into the inlet of the ETM. The ETM in this example was controlled by an electronic control module ECM, similar to the examples described above. [0146] The experiment included operating the engine, and applying voltage drive waveforms to successive stages of the ETM. Figure 6D includes a graphical representation of the results of this experiment 660 with a plot of number of particles per cubic centimeter against a logarithmic scale of the respective size of the particles (in nanometers).

[0147] Without the ETM operable 661 , the concentration of particles below 100nm in size was highest at about 300 million per cubic centimeter. Remaining grid lines 662, 663, 664, and 665 display the experimental results obtained by

successively operating stages one to four - from inlet to outlet. That is, 662 was obtained with the first stage closest the inlet operable only, and 664 was obtained with all stages in operation. As can be seen, increasing the number of stages increased agglomeration of particulate matter, pushing the peak particle size from below 100 nm to toward 1000 nm. Moreover, as the particles agglomerate, the concentration of particles also decreases as shown.

[0148] Example: Conti Emitec Test

[0149] A further example of an experiment conducted in relation to an apparatus 600 for agglomerating particulate matter in a diesel engine exhaust, also referred to as an exhaust treatment module (ETM), will now be described with reference to Figures 7A to 7C.

[0150] In this example, the ETM was similar to that described above in relation to Figures 6A to 6D, and included four stages where each stage included five piezoelectric ceramic cylinders coupled in series. The diameters of the stages increased from inlet to outlet - herein referred to as stage 1 to stage 4.

[0151] The experimental setup included a diesel engine E, and turbocharger TC. Emissions were guided into the ETM, and validation was performed by a DSM500 fast particle analyser and FTIR which were positioned both before and after the ETM. Temperature TEMP and pressure P was sensed as indicated in Figure 7B.

[0152] Figure 7C includes a graphical representation of the results of the experiment, including a plot 760 of number of particles per cubic centimeter against a logarithmic scale of particle size. [0153] With the ETM off 761 , concentrations of particles about 65 nm in size were over 300 million per cubic centimeter. With all stages of the ETM in operation, the concentrations of 65nm particles were significantly lowered to less than 50 particles per cubic centimeter, and the concentration of larger sized particles around 350 nm was increased.

[0154] An example of a method for designing an apparatus for agglomerating particulate matter in a fluid will now be described with reference to Figure 8. In particular, this method may be used in designing an apparatus according to any of the examples herein. In this example, the method includes using an electronic processing device, such as any of the processing devices described herein. In the preferred embodiment, the processing device will include a PC, smartphone, tablet, remote processing device, cloud-based and/or distributed architecture, or the like, such as described above.

[0155] In any event, the method includes, at step 800, determining at least one conduit parameter indicative of a characteristic of the conduit. This may be any suitable characteristic of the conduit, including a residence time relating to the time the fluid requires exposure to acoustic energy in order to achieve appropriate agglomeration of the entrained particles. Other suitable characteristics may include an approximate, expected or actual flowrate of the fluid in the conduit, a shape (actual, expected or approximate) of the conduit/piezoelectric actuator and/or an inner and/or outer diameter of the conduit or piezoelectric actuator.

[0156] Optionally at step 810 the method includes determining at least one manufacturing constraint. A manufacturing constraint can include any suitable constraint relating to manufacture of the apparatus or conduit, and most typically relates to constrains regarding the piezoelectric actuator, or a desired shape of the conduit or piezoelectric actuator. For example, the manufacturing constraint may include a thickness of the piezoelectric actuator, a length of the piezoelectric actuator and/or a shape of the piezoelectric actuator.

[0157] At step 820, the method includes generating a model of the conduit using the conduit parameter(s). If a manufacturing constraint is determined, this step also includes modelling the conduit using the manufacturing constraint(s). This can include any suitable form of modelling, including generating a geometric mesh indicative of the conduit, the mesh being defined by one or more element equations, boundary conditions, and the like.

[0158] At step 830, the method further includes determining at least one eigenfrequency (also referred to as a natural frequency) of the conduit using the model. This may be performed in any suitable manner, including analytically or numerically computing the eigenfrequency using the model, model parameters or the like. Most typically, this step is performed numerically, such as using a finite element analysis and this will be described below in more detail. In some instances, the eigenfrequency is calculated in accordance with an agglomeration frequency. For example, if the model defines multiple eigenfrequencies, the eigenfrequency/ies closest to the agglomeration frequency may be calculated. This can be

advantageous if a desired type of agglomeration is more likely to occur at frequencies closer to the agglomeration frequency. For example, in one instance, one or more eigenfrequencies closest to 20kHz may be determined, and

experimental evidence suggests frequencies in this range may be more likely to induce agglomerations around 50-500 nm. Additionally or alternatively, this step may include calculating eigenfrequencies in accordance with the model based on changes to the dimensions of the conduit.

[0159] Once the eigenfrequency/ies are calculated, at step 840 the method includes optimizing a sound pressure level using the at least one eigenfrequency and the model. Typically, this includes calculating the sound pressure level generated in the conduit at each of the determined eigenfrequencies and selecting the eigenfrequency and corresponding conduit which results in the optimum sound pressure level.

[0160] In the preferred embodiment, finite element analysis is used.

Accordingly, steps 820 to 840 further include generating a mesh indicative of the conduit and using finite element analysis to calculate the at least one eigenfrequency of the conduit using the mesh. Moreover, a sound pressure level is optimized using the mesh and the at least one eigenfrequency. In a particular instance, the finite element analysis is performed using a software package referred to by the trade name COMSOL (https://www.comsol.co.in/multiphysjcs/eigenfrequency-anaiys js), however this is not essential and other modelling software or methods may be used.

[0161] At step 850 of the method, one or more manufacturing and/or operating parameters are generated in accordance with the optimization. Such manufacturing parameters may include the inner and/or outer diameter of the conduit and/or piezoelectric actuator, the length of the conduit and/or piezoelectric actuator, a number of piezoelectric actuators in a respective conduit, and/or a number of conduits. Moreover, operating parameters may include an operating frequency, or at least an initial operating frequency. This may, for example, correspond to the frequency of the voltage drive waveform to be applied to the actuator. For example, the operating frequency may be selected as the eigenfrequency which resulted in the optimal (or maximum) sound pressure level found at step 840. In terms of the number of conduits, the abovementioned method may be used to determine a desired number of conduits including their respective dimensions, such that staged agglomeration, as discussed in more detail above.

[0162] A further example of a method for designing an apparatus for agglomerating particulate matter in a fluid will now be described with reference to Figure 9. In this example, the apparatus is for use in vehicle exhaust systems in order to agglomerate diesel particulate matter (DPM) in exhaust emissions.

[0163] In this example, the method of designing each conduit (also referred to as stages in this example) for the exhaust emission is calculated. Successive stages from inlet to outlet of the apparatus process typically proceed from higher to lower frequency, which corresponds to smaller to larger diameters.

[0164] In any event, for each stage at step 900, the length and diameter of the piezoelectric ceramic in that stage is determined at step 910. In this example, the diameter is selected such that the apparatus is similar or smaller in diameter to the diameter of the vehicle exhaust system. This is to ensure that back pressure in the engine is not generated by apparatus having a larger diameter than the exhaust. In addition, it is typically desirable for the outer diameter of piezoelectric ceramics in stage to be substantially the same as the inner diameter of the ceramics in an adjacent stage. This can be beneficial in ensuring a smoother transition between stages, and can reduce the turbulence of the fluid flow in the apparatus.

[0165] Also, the length of the stage is determined, typically using heuristics based upon experimental evidence, however this may be determined using an expected flow rate and required residence time of the fluid in the stage. Typically, a length of 150 mm is selected for this application, and this corresponds to five piezoelectric ceramic cylinders coupled in series, each one 30 mm long.

[0166] At step 920, the thickness of the piezoelectric ceramics in the stage are determined. This step can also be determined experimentally and/or via heuristics and/or manufacturing constraints. For example, a thickness of about 4, 5 or 6 mm may be selected.

[0167] Once the above dimensions are determined, at step 930 and electronic processing device is used to create a mesh of the ceramic actuators in the stage, and to calculate a number of eigenfrequencies using finite element analysis (FEA). Typically, five to seven eigenfrequencies are calculated. In particular, the

eigenfrequencies are selected for the proximity to the desired frequency of the stage. For an initial stage, or stage adjacent the inlet, the desired frequency in this type of application is around 20-21 kHz. This is a heuristic based upon experimental evidence that small particles in DTM can be appropriate agglomerated using acoustic energy starting from around 20 to 21 kHz. The desired frequencies of successive stages decrease, as discussed above, for example by 2kHz per stage (thus stage 2 may include a desired frequency of 19kHz, then 17kHz, 15kHz, or the like).

[0168] Once about five to seven eigenfrequencies are calculated, at 940 the sound pressure level (SPL) inside the stage is calculated at each of these

eigenfrequencies. The eigenfrequency which produces the optimal SPL (for example, the maximum SPL), is selected as a potential operating frequency for the stage.

[0169] Optionally, as step 960, the method may include checking whether the selected thickness for this stage is suitable for manufacture. If it is, the operating frequency selected at step 950 will be noted as the initial operating frequency for the driving voltage waveform for the piezoelectric ceramics in this stage. If it is not suitable to manufacture ceramics at this thickness, a more suitable thickness is obtained form the manufacturer and steps 920 to 960 repeated in order to select the operating frequency.

[0170] Accordingly, the above method facilitates the design of apparatus for agglomerating particulate matter in vehicle exhaust system, which is particularly energy efficient as each stage operates at a frequency which maximizes sound pressure. Additionally, this removes the need for expensive or compact diesel particulate filters, which can cause the engine to underperform under the influence of back pressure.

[0171] The number of stages in the above example can be calculated in any suitable manner, including heuristics determined using experimentation. In one example, the number of stages is calculated by approximating or evaluating the expected flow rate of exhaust through the system, determining the desired resident time for fluid in the system in order to optimize agglomeration, and calculated the number of modules based on these parameters. For example, in DPM exhaust applications, fluid may require about 0.3 seconds resident time in the apparatus to achieve appropriate agglomeration, and with each stage a standard 150 mm and an expected flow rate of 20 m/s, this would result in four stages.

[0172] Embodiments of the present invention comprise particulate agglomeration systems and methods. Advantageously these methods and apparatus provide an efficient way to increase particle size and decrease particle concentration in a fluid, including exhaust emissions.

[0173] In this patent specification, adjectives such as first and second, left and right, upper and lower, top and bottom, etc., are used solely to define one element or method step from another element or method step without necessarily requiring a specific relative position or sequence that is described by the adjectives.

[0174] According to one aspect, the invention provides a particulate matter agglomeration system including: an acoustic chamber for receiving an aerosol; ultrasonic piezoelectric ceramics for making ultrasonic field; and at least one electrode which applies an electric charge into the piezoelectric ceramics. The system connects to a power supply through electrode cables. A covering frame dissipates heat from the system. Aerosol enters into the system through an inlet flow and is agglomerated when passing through the system.

[0175] Advantages of the present invention include cost effective and efficient agglomeration of aerosols, which in certain applications can increase personal safety for humans working in association with, systems that generate such aerosols.

[0176] In some embodiments, the present invention, has no mechanical parts. This makes this system easy to maintain, more efficient, and subject to less operational faults.

[0177] In some embodiments, the present invention allows for diesel machinery to be more safely operated in areas without good ventilation due to improved filtration of diesel and dust particulate from the machinery and its operation.

[0178] A further example of an apparatus for agglomeration of particulate matter entrained in a fluid will now be described with reference to Figures 5A to 5C.

[0179] In this example, Figure 5A illustrates a front perspective view of a particulate agglomeration system 500 for an exhaust of a diesel engine, according to some embodiments of the present invention. Figure 5B illustrates a side view of an acoustic chamber of the particulate agglomeration system 500, according to some embodiments of the present invention. This system 500 includes an acoustic chamber 501.

[0180] Figure 5D illustrates a front view of the acoustic chamber of the particulate agglomeration system 500 of this example. Figure 5D illustrates a longitude cross section of a particulate agglomeration system 100. Fluid flow 505 carries any particulate matter to the acoustic chamber 501. FIG 3 illustrates that piezoelectric ceramics 502 are embedded through the acoustic chamber 501. The at least one electrode 503 conduct electrical charges to the poles of piezoelectric ceramics 502. The piezoelectric vibrates according to the power supply frequency. Electrode cables 504 connects a power supply to the at least one electrode 503. Based on the frequency of alternative power, the piezoelectric ceramics 502 propagate ultrasound within the acoustic chamber 501.

[0181] The particulate matter agglomeration system 500 is elongate in shape and the fluid flow 505 passes through the acoustic chamber 501. This forces particulate matters into the chamber 501 , which then travel through at least part of the chamber 501 , where they are exposed to acoustic field before exiting the chamber 501.

[0182] The piezoelectric ceramics 502 are located along at least part of the chamber 501 such that the piezoelectric ceramics 502 assemblies can be installed for operation perpendicular to the flow of the particulate matter. This enables high acoustic intensity across the entire flow.

[0183] As illustrated in Figure 5D, in some embodiments the agglomeration system 500 comprises at least one longitudinal piezoelectric ceramic and/or at least one electrode, that is at least partially embedded in the acoustic chamber 501.

[0184] The covering frame of the system 500 is thermally conductive and functions to dissipate at least some of the heat from the system 500.

[0185] In use, fluid containing particulate matters with a diameter great than, for example 100 nm, can enter the particulate agglomeration system 500 with fluid flow 505. The fluid then travels along at least part of the chamber 501 , before exiting from the chamber 501. While in the chamber 501 , the particulate matter is exposed to ultrasonic pressure waves from the ultrasonic piezoelectric ceramics, which causes the particulates of the fluid to agglomerate.

[0186] The piezoelectric ceramics flexes with the application of voltage. A control module (not shown), causes a modulated voltage to be applied to the piezoelectric ceramics which in turn causes the piezoelectric ceramics to vibrate at ultrasonic inaudible frequencies. The piezoelectric ceramics then couples the acoustic energy/pressure field to the particulate matters via fluid.

[0187] The piezoelectric ceramics typically operates in conditions where an eigenfrequency dominates within the chamber. For a specific material type of piezoelectric ceramics, the physical properties (e.g., the geometry i.e. external diameter (OD), internal diameter (ID) and length of chamber) can at least partially define the ultrasound eigenfrequencies of the chamber. These are the frequencies and corresponding pressure fields where the Helmholtz equation and boundary conditions can be satisfied with no external drive.

[0188] An example of suitable piezoelectric ceramics made from PSnN-5 material is 48 mm in OD and 44 mm in ID with the length of 30 mm. A finite elemental modelling analysis, using FEA software and in one example the software referred to by trade mane COMSOL Multiphysics software, shows an eigenfrequency of 20685 Hz within the chamber contains exhaust air at 100 °C. At these conditions, the pressure would reach substantially up to 3.5 Pa and the Sound Pressure Level (SPL) would reach above 100 dB within the chamber. This pressure level could be used to at least partially agglomerate particulate matter in the fluid passing through the acoustic chamber.

[0189] In summary, advantages of the present invention include simplicity, cost effective and efficient agglomeration of particulate matters in any fluid-solid phases. The present invention can increase personal safety for people working in association with systems that generate such aerosols, and/or decrease the environmental impact of an increasing proportion of particulate matters which could be agglomerated. According to certain embodiments, diesel machinery areas polluted with silica dust can be more safely operated in areas without good ventilation due to improved filtration of particulate from the machinery.

[0190] The articles“a” and“an” are used herein to refer to one or to more than one (i.e. to at least one) of the grammatical object of the article. By way of example, “an element” means one element or more than one element.

[0191] As used herein,“and/or” refers to and encompasses any and all possible combinations of one or more of the associated listed items, as well as the lack of combinations when interpreted in the alternative (or).

[0192] Further, the term“about”, as used herein when referring to a measurable value such as an amount, dose, time, temperature, activity, level, number, frequency, percentage, dimension, size, amount, weight, position, length and the like, is meant to encompass variations of ± 20%, ± 10%, ± 5%, ± 1%, ± 0.5%, or even ± 0.1% of the specified amount, dose, time, temperature, activity, level, number, frequency, percentage, dimension, size, amount, weight, position, length and the like.

[0193] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, preferred methods and materials are described.

[0194] Throughout this specification and the claims which follow, unless the context request otherwise, the word“comprise”, and variations such as“comprises” and“comprising”, will be understood to imply the inclusion of a stated integer or step or group of integers of steps but not to the exclusion of any other integer or step or group of integers.

[0195] Persons skilled in the art will appreciate that numerous variations and modifications will become apparent. All such variations and modifications which become apparent to persons skilled in the art, should be considered to fall within the spirit and scope that the invention broadly appearing before described.

[0196] Thus, for example, it will be appreciated that features from different examples above may be used interchangeably where appropriate.