WO2021038194A1 - Nonthermal plasma generator and method of manufacturing the same - Google Patents

Nonthermal plasma generator and method of manufacturing the same Download PDF

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Publication number
WO2021038194A1
WO2021038194A1 PCT/GB2020/051963 GB2020051963W WO2021038194A1 WO 2021038194 A1 WO2021038194 A1 WO 2021038194A1 GB 2020051963 W GB2020051963 W GB 2020051963W WO 2021038194 A1 WO2021038194 A1 WO 2021038194A1
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Prior art keywords
electrodes
plasma generator
electrode
nonthermal plasma
pair
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PCT/GB2020/051963
Other languages
French (fr)
Inventor
Ahmed Hussein
Keith Parker
Adrian SCHMIEDER
Hagen MOON
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Hieta Technologies Limited
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Publication of WO2021038194A1 publication Critical patent/WO2021038194A1/en

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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H1/00—Generating plasma; Handling plasma
    • H05H1/24—Generating plasma
    • H05H1/2406—Generating plasma using dielectric barrier discharges, i.e. with a dielectric interposed between the electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/32—Gas-filled discharge tubes
    • H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
    • H01J37/32348—Dielectric barrier discharge
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
    • C01B3/02—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen
    • C01B3/32—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air
    • C01B3/34—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air by reaction of hydrocarbons with gasifying agents
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/32—Gas-filled discharge tubes
    • H01J37/32431—Constructional details of the reactor
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/32—Gas-filled discharge tubes
    • H01J37/32431—Constructional details of the reactor
    • H01J37/32532—Electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/32—Gas-filled discharge tubes
    • H01J37/32431—Constructional details of the reactor
    • H01J37/32532—Electrodes
    • H01J37/32568—Relative arrangement or disposition of electrodes; moving means
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/32—Gas-filled discharge tubes
    • H01J37/32431—Constructional details of the reactor
    • H01J37/32798—Further details of plasma apparatus not provided for in groups H01J37/3244 - H01J37/32788; special provisions for cleaning or maintenance of the apparatus
    • H01J37/32816—Pressure
    • H01J37/32834—Exhausting
    • H01J37/32844—Treating effluent gases
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H1/00—Generating plasma; Handling plasma
    • H05H1/24—Generating plasma
    • H05H1/2406—Generating plasma using dielectric barrier discharges, i.e. with a dielectric interposed between the electrodes
    • H05H1/2431—Generating plasma using dielectric barrier discharges, i.e. with a dielectric interposed between the electrodes using cylindrical electrodes, e.g. rotary drums
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B33—ADDITIVE MANUFACTURING TECHNOLOGY
    • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y80/00—Products made by additive manufacturing
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
    • C01B2203/08—Methods of heating or cooling
    • C01B2203/0805—Methods of heating the process for making hydrogen or synthesis gas
    • C01B2203/0861—Methods of heating the process for making hydrogen or synthesis gas by plasma
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
    • C01B2203/12—Feeding the process for making hydrogen or synthesis gas
    • C01B2203/1205—Composition of the feed
    • C01B2203/1211—Organic compounds or organic mixtures used in the process for making hydrogen or synthesis gas
    • C01B2203/1235—Hydrocarbons
    • C01B2203/1247—Higher hydrocarbons
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/06—Combination of fuel cells with means for production of reactants or for treatment of residues
    • H01M8/0606—Combination of fuel cells with means for production of reactants or for treatment of residues with means for production of gaseous reactants
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H2240/00—Testing
    • H05H2240/20—Non-thermal plasma
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02C—CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
    • Y02C20/00—Capture or disposal of greenhouse gases
    • Y02C20/30—Capture or disposal of greenhouse gases of perfluorocarbons [PFC], hydrofluorocarbons [HFC] or sulfur hexafluoride [SF6]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present technique relates to the field of plasma generators, in particular nonthermal plasma generators and methods for their manufacture.
  • Nonthermal plasma also referred to as cold plasma or non-equilibrium plasma
  • cold plasma or non-equilibrium plasma is a particular type of plasma that is not in thermodynamic equilibrium, since the electron temperature is much hotter than the temperatures of the ions and neutrals.
  • Nonthermal plasma is typically produced in low pressure discharges or in short pulse discharged such as Dielectric Barrier Discharges (DSD) or nanosecond discharges.
  • DSD Dielectric Barrier Discharges
  • Nonthermal plasma generators have a variety of applications, such as reducing the emission of nitrogen oxides in the exhaust gases of diesel automotive engines. Additionally, in the case of dual-fuel automotive engines, nonthermal plasma generators can be used to reduce the amount of methane in the exhaust gases. In such applications, collisions between the hot electrons in the plasma and the cold gas molecules lead to dissociation reactions and the formation of radicals. The presence of a catalyst, such as platinum or rhodium, can further enhance the conversion of reactants in order to alter the chemical composition of the gas in the exhaust.
  • a catalyst such as platinum or rhodium
  • Nonthermal plasma generators provide a means to reform fuel to produce hydrogen which eliminates the problems encountered in the catalytic reformers.
  • Nonthermal plasma generators for such automotive applications can be designed to be retrofitted into an existing exhaust system, so must conform to the dimensions of the exhaust. Accordingly, there is a need to provide smaller, more efficient nonthermal plasma generators and means to manufacture such nonthermal plasma generators in order to provide more plasma for a given size of nonthermal plasma generator or a given input energy.
  • At least examples provide a method of manufacturing a nonthermal plasma generator, wherein the nonthermal plasma generator is built as an integrated mass of material using an additive manufacture process, the nonthermal plasma generator including a plurality of electrodes arranged in at least one pair, wherein a separation between the electrodes in each pair of electrodes is controlled by the additive manufacture process.
  • At least some examples provide nonthermal plasma generator built using the method of manufacture as discussed above.
  • At least some examples provide a nonthermal plasma generator built as an integrated mass of material using an additive manufacture process, the nonthermal plasma generator comprising a plurality of electrodes arranged in at least one pair, wherein a separation between the electrodes in each pair of electrodes is controlled by the additive manufacture process.
  • At least some examples provide an exhaust gas processing system comprising the nonthermal plasma generator as discussed above or a fuel cell system comprising the nonthermal plasma generator as discussed above.
  • At least some examples provide a computer-readable data structure representing a design of a nonthermal plasma generator as discussed above. At least some examples provide a computer-readable data structure representing machine instructions which, when performed by an additive manufacturing machine, cause the additive manufacture machine to perform the method of manufacture as discussed above.
  • the data structure may be stored on the storage medium.
  • the storage medium may be a non-transitory storage medium.
  • Figure 1 schematically illustrates an example of a non-thermal plasma generator
  • Figures 2 and 3 schematically illustrate a cross-section through one pair of electrodes of the nonthermal plasma generator
  • Figure 4 schematically illustrates an interconnected array of electrodes of a non thermal plasma generator
  • Figure 5 schematically illustrates a cross-section through an interconnected array of electrodes of a non-thermal plasma generator
  • Figure 6 schematically illustrates an interconnected array of electrodes of a non thermal plasma generator
  • Figure 7 schematically illustrates a cross-section through an interconnected array of electrodes of a non-thermal plasma generator
  • Figure 8 schematically illustrates a further example of an interconnected array of electrodes of a non-thermal plasma generator
  • Figure 9 schematically illustrates an inlet of a nonthermal plasma generator
  • Figure 10 schematically illustrates a cross-section through an inlet of a nonthermal plasma generator
  • Figure 11 schematically illustrates an exploded view of components of a nonthermal plasma generator
  • Figure 12 shows one example of manufacturing equipment for manufacturing the nonthermal plasma generator by additive manufacture
  • Figure 13 is a flow diagram illustrating a method of manufacturing a nonthermal plasma generator
  • Figure 14 is a flow diagram illustrating a method of manufacturing a nonthermal plasma generator
  • a method of manufacturing a nonthermal plasma generator wherein the nonthermal plasma generator is built as an integrated mass of material using an additive manufacture process.
  • the nonthermal plasma generator includes a plurality of electrodes arranged in at least one pair. This beneficially allows the nonthermal plasma generator to be manufactured as a single part, and in particular allows the electrodes to be manufactured as part of the same integrated mass of material as the remainder of the nonthermal plasma generator. In other words, the nonthermal plasma generator can be manufactured as a single part without having to separately manufacture the electrodes and assemble them later. This results in fewer parts needing to be manufactured and fewer assembly steps.
  • Combining the electrodes into the same integrated mass of material also reduces the amount of arcing in the nonthermal plasma generator, since the electrodes are made of the same material and there are no discontinuities or joins, such as weld lines. Such discontinuities or joins would create changes in materials or surface finish which can promote arcing.
  • Providing a nonthermal plasma generator with integral electrodes therefore reduces arcing, which in turn increases the amount of plasma that can be produced for a given input energy.
  • a separation between the electrodes in each pair of electrodes is controlled by the additive manufacture process.
  • the position and location of the electrodes within the nonthermal plasma generator is a result of the manufacture using the additive manufacture process.
  • the separation between each electrode in each pair of electrodes in other words the distance between each electrode in each pair of electrodes, is maintained by controlling the additive manufacture process to ensure the completed nonthermal plasma generator has the intended separation between the electrodes.
  • the surface finish of the electrodes can be controlled by the additive manufacture process, which in turn controls the separation between the electrodes and reduces the amount of arcing in the nonthermal plasma generator.
  • the nonthermal plasma generator comprises a dielectric material inserted in the separation between the electrodes in each pair of electrodes.
  • the dielectric material acts as an electric insulator between the electrodes in each pair of electrodes, thereby preventing arcing of the electrodes.
  • a first electrode in each pair of electrodes comprises an elongate wire.
  • each of the elongate wires has a diameter of between 1mm and 2mm. This increases the surface area of the first electrode whilst providing a small volume of material.
  • the elongate wires are parallel with one another. This increases the packing density of the electrodes, thereby allowing more electrodes to be arranged in a fixed volume.
  • a build direction of the additive manufacture process is along a length of the elongate wires. Elongate structures can be unstable during the additive manufacture process as they are only supported at one end.
  • a second electrode in each pair of electrodes comprises a tube portion surrounding the first electrode, and for each pair of electrodes the separation controlled by the additive manufacture process is between the first electrode and the tube portion of the second electrode.
  • each pair of electrodes comprises a tube portion with an elongate wire electrode passing along the tube portion.
  • the nonthermal plasma generator comprises a plurality of pairs of electrodes, and the second electrodes in each pair of electrodes are arranged to form an interconnected array of electrodes.
  • all of the second electrodes are grouped together such that they form a single mass of material, thereby reducing the separation between each pair of electrodes and increasing the density of electrodes. In other words, more electrodes can be contained within a fixed volume.
  • the first electrode is positioned substantially along a centre of the tube portion of the second electrode. This means the separation between the first electrode and the second electrode is substantially the same around the circumference of the tube portion of the second electrode, which results in a more even distribution of plasma in the tube portion of the second electrode.
  • the nonthermal plasma generator comprises a tube of dielectric material in the separation between the first electrode and the second electrode of each pair of electrodes. As discussed above, this acts as an electric insulator between the electrodes in each pair of electrodes, thereby preventing arcing of the electrodes.
  • the dielectric material can be contained within the tube portion of the second electrode, such that the external volume or shape of the pair of electrodes is not increased due to the inclusion of the dielectric material. Tubes of dielectric material are also easier to coat with a catalyst or other surface coating than a more complex structure, in particular since the catalyst coating may be particularly thin, for example 50 to 100 pm.
  • each tube of dielectric material is configured such that a separation between the tube of dielectric material and the first electrode is greater than a separation between the tube of dielectric material and the second electrode for each pair of electrodes. This means the dielectric material is located closer to the second electrode, thereby increasing the amount of gas that can be contained between the dielectric material and the first electrode, thereby ensuring that the majority of the plasma is generated between the first electrode and the dielectric material whilst increasing the amount of gas that can flow in the separation between the first electrode and the dielectric material.
  • the nonthermal plasma generator comprises an inlet to direct a gas into the separation between the electrodes in each pair of electrodes. This ensures that gas is able to flow into the separation between the electrodes in each pair of electrodes, so that the gas in the separation between the electrodes in each pair of electrodes can be ionised to form plasma.
  • the inlet comprises a mesh. The mesh creates a more even distribution of gas into each pair of electrodes. In other words, the gas flow into the separation between the electrodes in each pair of electrodes is substantially the same for each pair of electrodes.
  • the nonthermal plasma generator comprises a nest connected to a first end of the first electrode of each pair of electrodes, wherein the nest is configured to provide a voltage to each of the first electrodes from an external supply. This allows each of the first electrodes to be provided with voltage from the same external supply, whilst also allowing the nest to be integrally formed with the first electrodes.
  • the method of manufacture comprises starting the build of the nonthermal plasma generator using the additive manufacture process, stopping the build of the nonthermal plasma generator prior to the end of the build, inserting one or more components into the nonthermal plasma generator and continuing the build of the nonthermal plasma generator.
  • an additional component can be inserted into the nonthermal plasma generator during the manufacture of the nonthermal plasma generator, thereby allowing the additional component to be added in a location entirely contained within the nonthermal plasma generator which is not otherwise accessible once the nonthermal plasma generator is fully manufactured.
  • This provides greater design scope for nonthermal plasma generator, since the location of additional components is not limited by access constraints of the manufactured nonthermal plasma generator.
  • the additional component can be entirely contained within the nonthermal plasma generator, and even inside a wall of the nonthermal plasma generator.
  • the one or more components are formed of a dielectric material and in some examples a component of the one or more components is inserted in the separation between the electrodes in each pair of electrodes.
  • the dielectric material can be used to prevent arcing of the electrodes. By stopping the build and inserting the dielectric component in the separation between the electronics, a more complex electrode geometry can be formed since the dielectric material can be added during manufacture of the electrodes rather than afterwards.
  • the additive manufacture process may be controlled by supplying an electronic design file which represents characteristics of the design to be manufactured, and inputting the design file to a computer which translates the design file into instructions supplied to the manufacturing device.
  • the computer may slice a three-dimensional design into successive two-dimensional layers, and instructions representing each layer may be supplied to the additive manufacture machine, e.g. to control scanning of a laser across a powder bed to form the corresponding layer.
  • the technique could also be implemented in a computer-readable data structure which represents the design of a nonthermal plasma generator as discussed above.
  • the computer-readable data structure comprises a computer automated design (CAD) file.
  • CAD computer automated design
  • a storage medium may be provided storing the data structure.
  • FIG. 1 schematically illustrates an example of a non-thermal plasma generator 100.
  • the nonthermal plasma generator 100 is built as an integrated mass of material using an additive manufacture process.
  • the nonthermal plasma generator 100 includes a plurality of electrodes arranged in at least one pair.
  • Figure 2 schematically illustrates a cross-section through one pair of electrodes 200 of the nonthermal plasma generator 100.
  • the pair of electrodes comprises a first electrode 202 and a second electrode 204.
  • the distance between the first electrode 202 and the second electrode 204 in each pair of electrodes 200 is maintained during manufacture process by controlling the additive manufacture process. This is in contrast to existing methods where one or more of the electrodes are added to the nonthermal plasma generator after manufacture of the nonthermal plasma generator, creating additional assembly steps.
  • all of the electrodes are formed as part of the same integrated mass of material, and therefore the separation 206 between the electrodes 202, 204 must be maintained, in other words controlled, during the manufacture of the nonthermal plasma generator 100.
  • the first electrode 202 in each pair of electrodes 200 comprises an elongate wire.
  • the first electrode 202 is a slender body with a length several times greater than its width.
  • the diameter of the wire may be between 1 mm and 2mm whilst the length of the wire is between 10 and 50mm.
  • the cross-section is taken through the width or diameter of the elongate wire in a direction perpendicular the length of the elongate wire.
  • the first electrode in Figures 2 has a circular cross-section, it will be appreciated that the first electrode may comprise an elongate wire with any shape of cross-section, such as a rectangle, triangle, polygon, ellipse or crescent shaped.
  • the second electrode 204 in each pair of electrodes 200 comprises a tube portion surrounding the first electrode.
  • the second electrode 204 has a hollow portion, and the first electrode passes through or is at least partially contained within the hollow portion of the second electrode 204.
  • the separation between the first electrode 202 and the tube portion of the second electrode 204 is controlled by the additive manufacture process.
  • the first electrode 202 is positioned substantially along a centre of the tube portion of the second electrode 204.
  • the first electrode 202 may be located anywhere within the tube portion of the second electrode 204, thereby providing a difference in separation 206 around the circumference of the first electrode 202 and the tube portion of the second electrode 204. This is beneficial in applications where a variation in gas and plasma distribution in the separation 206 between the first electrode 202 and the second electrode 204 is desired. It will be appreciated, however, that although the tube portion of the second electrode in Figure 2 has a circular cross-section, the tube portion of the second electrode may have any shape of cross-section, such as a rectangle, triangle, polygon, ellipse or crescent shaped.
  • the first electrode 202 comprises an elongate wire and the second electrode 204 comprises a tube portion surrounding the elongate wire
  • the pair of electrodes 200 may be formed of any shape.
  • the first electrode 202 and the second electrode 204 may each be a flat plate arranged parallel to one another so as to provide a constant separation 206 between the pair of electrodes 200.
  • the first electrode 202 and the second electrode 206 may not be parallel to each other, thus creating a varying separation between the electrodes for applications where such a variation in gas and plasma distribution in the separation between the electrodes is desired.
  • the first electrode 202 and the second electrode 204 may both comprise elongate wires, or the first electrode 202 may comprise an elongate wire whilst the second electrode 204 comprises a flat plate. It will therefore be appreciated that the first electrode 202 and the second electrode 204 may be any shape, and the shape of the first electrode and the second electrode need not be the same.
  • the nonthermal plasma generator 100 comprises a dielectric material inserted in the separation 206 between the electrodes 202, 204 in each pair of electrodes 200.
  • a material is inserted between the first electrode 202 and the second electrode 204 of each pair of electrodes 200 to act as an electrical insulator between the first electrode 202 and the second electrode 204, thereby preventing arcing of any gas between the pair of electrodes 200.
  • Figure 3 schematically illustrates the same cross-section through a pair of electrodes 200 as illustrated in Figure 2, but with a dielectric material 300 inserted in the separation 206 between the first electrode 202 and the second electrode 204 in the each pair of electrodes 200.
  • the dielectric material 300 may be a ceramic material, such as aluminium oxide, or any other material with good electrical insulator properties.
  • the dielectric material 300 may also be coated in one or more catalysts, such as platinum or rhodium, in order to enhance the conversion of reactants in the plasma generator in order to alter the chemical composition of the gas proximate to the electrodes, particular in the automotive engine exhaust applications as described above.
  • the dielectric material 300 is a tube of dielectric material in the separation 206 between the first electrode 202 and the second electrode 204.
  • the dielectric material 300 passes through or is at least partially contained within the hollow portion of the second electrode 204, and the dielectric material 300 also has a hollow portion that the first electrode passes through or is at least partially contained within.
  • the tube of dielectric material 300 therefore surrounds the first electrode 202, and the tube of the second electrode 204 surrounds both the dielectric material 300 and the first electrode 202 so that the dielectric material 300 is between the first electrode 202 and the second electrode 204.
  • the tube of dielectric material 300 is configured such that a separation 302 between the tube of dielectric material 300 and the first electrode 202 is greater than a separation 304 between the tube of dielectric material 300 and the second electrode 204. As shown in Figure 3, this allows for a larger volume of gas between the tube of dielectric material 300 and the first electrode 202 than between the tube of dielectric material 300 and the second electrode 204. In some examples, there is no separation 304 between the tube of dielectric material 300 and the second electrode 204, such that the dielectric material 300 is in contact with the second electrode 204. In this case, the only volume of gas in the separation 206 between the first electrode 202 and the second electrode 204 is in the separation 302 between the tube of dielectric material 300 and the first electrode 202.
  • the dielectric material 300 is a tube
  • the dielectric material 300 may be any shape suitable to be located in the separation between the first electrode 202 and the second electrode 204.
  • the dielectric material 300 may then also be a flat plate inserted parallel to the first electrode 202 and the second electrode 204 in the separation 206 between the pair of electrodes 200.
  • Figures 2 and 3 illustrate a single pair of electrodes 200, it will be appreciated that the nonthermal plasma generator 100 may comprise multiple pairs of electrodes, for example 2, 10, 12, 50 or more. In other words, the nonthermal plasma generator 100 comprises a plurality of pairs of electrodes 200.
  • Figure 4 illustrates an example of an interconnected array of electrodes 210 of a non thermal plasma generator, for example the nonthermal plasma generator 100 illustrated in Figure 1.
  • Figure 5 then illustrates a cross-section through the interconnected array of electrodes 210 of a non-thermal plasma generator 100, the cross-section being taken through the section A-A as shown in Figures 1 and 4.
  • there are a plurality of pairs of electrodes for example those described above with reference to Figures 2 and 3.
  • the second electrodes 204A, 204B, 204N in each pair of electrodes are arranged to form the interconnected array of electrodes 210.
  • the second electrodes 204A, 204B, 204N in each pair of electrodes are arranged to form a single mass of material where each of the second electrodes 204A, 204B, 204N is connected to at least one other second electrode.
  • a gap 208 between the second electrodes this is not essential and it will be appreciated that the second electrodes 204A, 204B, 204N in each pair of electrodes may be arranged such that the only space or gap available for gas to pass through the interconnected array of electrodes 210 is in the tube portion of each of the second electrodes 204A, 204B, 204N.
  • the gap 208 may be sealed at one or both ends of the tube portion of the second electrodes 204A, 204B, 204N such that, although there are still one or more gaps 208 in the interconnected array of electrodes 210, gas is unable to follow into the one or more gaps 208. This reduces the mass of the part whilst ensuring that all of the gas passes in the tube portion of each of the second electrodes 204A, 204B, 204N.
  • the first electrodes 202A, 202B, 202N each comprise elongate wire, and the elongate wires are arranged in parallel with one another.
  • the first electrodes 202A, 202B, 202N are arranged such that the elongate wires are orientated in substantially the same direction, such that the elongate or long axis of each wire is aligned with the elongate or long axis of each other wire. In the example illustrated in Figure 4 this is orientated with the z axis.
  • each second electrode 204A, 204B, 204N is then also aligned such that the elongate or long axis of each tube is aligned with the elongate or long axis of each other tube, such that the interconnected array of electrodes 210 forms an elongate bundle of pairs of electrodes.
  • Figures 6 and 7 correspond, respectively, to Figures 4 and 5, but illustrate an example where a dielectric material 300A, 300B, 300N is inserted in the separation 206A, 206B, 206N between the electrodes in each pair of electrodes.
  • the dielectric material 300A, 300B, 300N is a tube inserted in the separation between the elongate wire first electrodes 202A, 202B, 202N and the tube portions of each second electrode 204A, 204B, 204N.
  • each tube of dielectric material 300A, 300B, 300N and each first electrode 202A, 202B, 202N may be greater than the separation between each tube of dielectric material 300A, 300B, 300N and each second electrode204A, 204B, 204N, but this is not essential.
  • the location of the tube of dielectric material 300 within the separation 206 between the first electrode 202 and the second electrode 204 may be different for one or more pairs of electrodes 200.
  • each pair of electrodes may comprise an elongate wire and a tube portion surrounding the elongate wire, but the diameters of the elongate wire and the tube portion may be different for each pair of electrodes.
  • one pair of electrodes may comprise an elongate wire and a tube portion surrounding the elongate wire whilst another pair of electrodes comprises a pair of parallel flat plates.
  • the interconnected array of electrodes 210 may take also take any shape. Although in Figures 4 to 7 the second electrodes 204A, 204B, 204N in each pair of electrodes are arranged to form an interconnected array of electrodes 210 in the shape of a grid of electrodes, it will be appreciated that this is not essential. For example, the second electrodes 204A, 204B, 204N in each pair of electrodes may be arranged to form a linear interconnected array of electrodes 210, where each second electrode 204 is only in directed contact with up to 2 other second electrodes 204 on opposite sides of each second electrode 204.
  • the second electrodes 204A, 204B, 204N in each pair of electrodes may be arranged to form a ring shaped interconnected array of electrodes 210.
  • the grid shaped interconnected array of electrodes 210 illustrated in Figures 4 to 7 advantageously maximises the number of pairs of electrodes that can be contained within a fixed volume for the interconnected array of electrodes 210. In other words, the packing density of the pairs of electrodes within the interconnected array of electrodes 210 is maximised.
  • the grid shaped interconnected array of electrodes 210 may be of any configuration depending on the number of pair of electrodes, such as 3x3, 2x3 or 3x4 as illustrated in Figures 4 to 7.
  • Figure 8 illustrates a further example of an interconnected array of electrodes 210 of a non-thermal plasma generator 100, but further comprising a nest 400.
  • the interconnected array of electrodes 210 may correspond to the interconnected array of electrodes 210 illustrated in Figures 4 and 6.
  • the nest 400 is connected to first end of the first electrode 202 of each pair of electrodes. In the example illustrated in Figure 8, this corresponds to an end of the elongate wire of each of the first electrode, in other words an end of the elongate or long axis of the elongate wire.
  • the nest 400 is configured to provide a voltage to each of the first electrodes 202 from an external supply.
  • the nest provides a means of interconnecting each of the first electrodes 202 such that all of the first electrodes 202 can be provided a voltage from the same external supply.
  • the external supply provides a 14kV voltage to the first electrodes 202.
  • the external supply can supply the voltage as a continuous voltage or as pulses as described above.
  • the voltage can be supplied as pulses with duration of the order of nanoseconds with the peak voltage of each pulse being of the order of kilovolts. It will be appreciated, however, that the exact form of the supplied voltage can be adapted for the specific application of the nonthermal plasma generator 100.
  • the nest 400 is formed of a plurality of interconnected wires, but this is not essential.
  • the nest 400 may be a flat plate connected to the first end of the first electrode 202 of each pair of electrodes.
  • the nest illustrated in Figure 8 comprises a top-hat 402 at the location where the nest connects to each first electrode 202. As described below, this helps to ensure a solid connection between each first electrode 202 and the nest 400 during the additive manufacturing process and allows the nest 400 to be manufactured separately from the first electrodes, but this is not essential.
  • the nest does not comprise any top-hats 402, such that the nest 400 provides a smooth continuation of each elongate wire.
  • the plurality of interconnected wires forming the nest 400 may have substantially the same diameter as the elongate wires forming the first electrodes 202.
  • the plurality of interconnected wires may also comprise one or more peaks 404 which provide a curve in the wire in a direction away from the first electrodes 202 and, as a result, the second electrodes 204. This increases the separation between the wires of the nest 400 and the second electrodes 204, thereby preventing arcing between the nest 400 and the second electrodes 204 since the separation between the nest 400 and the second electrodes 204 will be greater than the separation between the first electrode 202 and the second electrode 204 in each pair of electrodes 200.
  • the first electrode 202 in each pair of electrodes 200 may be configured to extend beyond the tube portion of the second electrode 204 to ensure that the separation 206 between the first electrode 202 and the second electrode 204 in each pair of electrodes 200 is at a minimum within the tube portion of the second electrode 204.
  • the nonthermal plasma generator 100 may also comprise a second nest connected to a second end of the first electrode 202 of each pair of electrodes.
  • the second end may be the end of the elongate wire opposite the first end connected to the first nest 400, such that there is a nest at each end of each elongate wire.
  • the second nest may be identical and comprise the same features as the first nest, but this is not essential and the second nest may take any form suitable to provide a connection to the second end of first electrode of each pair of electrodes.
  • the nonthermal plasma generator comprises an inlet.
  • Figure 9 schematically illustrates an example of such an inlet 500 of a nonthermal plasma generator 100.
  • the inlet directs a gas, such as an exhaust gas from an automotive engine, into the separation 206 between the electrodes 202, 204 in each pair of electrodes 200.
  • the inlet is located at a first end of the interconnected array of electrodes 210 described above.
  • the gas enters the inlet through an orifice 502, and is directed by the inlet into the separation 206 between the electrodes in each pair of electrodes of the interconnected array of electrodes 210.
  • the inlet 500 is configured such that all of the gas entering the orifice 502 is directed into the separation 206 between the electrodes in each pair of electrodes 200.
  • the first end of the interconnected array of electrodes 210 where the inlet 500 is located may correspond to the first end of the first electrode 202 of each pair of electrodes 200 where the nest 400 is located as described above with reference to Figure 8.
  • FIG 10 schematically illustrates a cross-section through the inlet 500 of a nonthermal plasma generator, where the cross-section is taken through the section B-B illustrated in Figure 9.
  • the inlet 500 comprises a hollow portion 504 which allows the gas to flow from the orifice 502 into the separation 206 between the electrodes in each pair of electrodes.
  • the velocity of the gas entering the inlet 500 may be of the order of 20 litre per minute.
  • the hollow portion 504 of the inlet 500 acts as a plenum or volume to reduce the velocity of the gas before the gas enters the separation 206 between the electrodes in each pair of electrodes. This increases the efficiency of the nonthermal plasma generator since more reactions within the gas, and therefore more changes in the chemical composition of the gas can occur as the gas travels along the separation 206 between the electrodes in each pair of electrodes.
  • the nest 400 is located within the hollow portion 504 of the inlet 500. Accordingly, the nest 400 may form part of the inlet 500, or may form part of the interconnected array of electrodes 210.
  • the inlet 500 also comprises one or more voltage supply channels 506A, 506B through which the voltage from the external supply can be provided to the electrodes.
  • the voltage from the external supply may be supplied to the nest 400 located within the hollow portion 504 of the inlet 500, and therefore to each of the first electrodes 202.
  • the inlet also comprises a mesh 510.
  • the mesh 510 introduces turbulence into the gas flowing into the inlet, which improves the distribution of gas within the hollow portion 504, thereby creating a more even distribution of gas into the separations between the electrodes in each pair of electrodes. In other words, the flow of gas around each of the first electrodes is substantially the same.
  • the mesh 510 is located between the orifice 502 and the hollow portion 504 of the inlet.
  • FIG 11 schematically illustrates an exploded view of components of the nonthermal plasma generator 100 illustrated in Figure 1 and described above.
  • the nonthermal plasma generator 100 comprises an inlet 500, interconnected array of electrodes 210, and an end cap 600.
  • the gas enters the inlet 500 through the orifice 502 (not shown), flows through the interconnected array of electrodes 210 by flowing along the separation between the electrodes in each pair of electrodes and into the end cap 600.
  • the end cap 600 comprises a port for the gas to flow out of the nonthermal plasma generator 100, for example into the exhaust system of an automobile.
  • the end cap 600 may also comprise one or more voltage supply channels through which a voltage can be removed from the nonthermal plasma generator 100, such as by connection to the second electrode 204 in each pair of electrodes.
  • the end cap 600 may also contain a second nest connected to the second end of each of the first electrodes as described above.
  • Figure 11 illustrates an exploded view of the components of the nonthermal plasma generator 100
  • the nonthermal plasma generator 100 may be built as an integrated mass of material.
  • the inlet 500, the interconnected array of electrodes 210 and the end cap 600 all form a single part.
  • the inlet 500, the interconnected array of electrodes 210 and the end cap 600 may be formed a three separate parts and assembled using conventional techniques such as bolted, welded or otherwise joined together.
  • the tubes of dielectric material 300 if present are inserted into the separation 206 prior to the inlet 500, the interconnected array of electrodes 210 and the end cap 600 being assembled together.
  • FIG 12 schematically illustrates an example of additive manufacture.
  • laser fused metal powder 188 is used to form an article 4 such as the nonthermal plasma generator 100 described above.
  • the article 4 is built in a build direction z by forming the article 4 layer-by-layer upon a lowering powder bed 180 on top of which thin layers of metal power to be fused are spread by a powder spreader 182 prior to being melted (fused) via a scanning laser beam provided from a laser 184.
  • Each layer is melted or fused onto the layer below it by the scanning laser beam. In regions where there is no material for the article directly below where the current layer is being formed, or there is an overlap between the layer currently being formed and the layer below, the material properties of the article 4 in these regions is reduced.
  • the article 4 such as the nonthermal plasma generator 100 as described above, can be designed so that the wall thickness of the part is increased in the regions as described above.
  • the build direction z of the additive manufacture process may be along a length of the elongate wires of the first electrode 202.
  • the build direction is in the elongate or long axis of the elongate wires of the first electrode 202, as indicated by the direction z in Figures 1 , 4,6 and 11.
  • This also assists in controlling the separation between the electrodes in each pair of electrodes during the additive manufacture process, since each layer used to form the first electrode and the second electrode is deposited directly on top of the previous layer of material. As a result, there are no overhangs during formation of the electrodes, and therefore the surface roughness of the material can be minimised and therefore the separation between the electrodes in each pair of electrodes maintained and controlled.
  • the thickness of the elongate wire may vary in the build direction z.
  • the amount of material and number of layers used to create the elongate wire varies as the nonthermal plasma generator is built.
  • the elongate wire may have an initial thickness in the build direction z which is greater than the thickness of the elongate wire along the majority of the build direction z.
  • the initial layers used to form the elongate wire may use more material than the remainder of the layers used to the form the elongate wire in order to provide additional support and strength to the elongate wire and prevent distortion of the elongate wire during the additive manufacture process.
  • each of the elongate wires may have this greater initial thickness for the same reasons as described above.
  • the scanning of the laser beam via the laser 184, and the lowering of the bed 180, are computer controlled by a control computer 186.
  • the control computer 186 is in turn controlled by a computer program (e.g. computer data defining the article 4 to be manufactured).
  • This article defining data is stored upon a computer readable non-transitory medium 198.
  • Figure 12 illustrates one example of a machine which may be used to perform additive manufacture.
  • Various other machines and additive manufacturing processes are also suitable for use in accordance with the present techniques, whereby a nonthermal plasma generator is manufactured with plurality of electrodes arranged in at least one pair as discussed above.
  • FIG 13 shows a method 700 for manufacturing a nonthermal plasma generator, such as the nonthermal plasma generator 100 described above.
  • a nonthermal plasma generator such as the nonthermal plasma generator 100 described above.
  • build of the nonthermal plasma generator 100 using the additive manufacture process is started, for example the additive manufacture process described in relation to Figure 12 above.
  • build of the nonthermal plasma generator 100 is stopped prior to the end of the build. In other words, the additive manufacture process is stopped prior to the final layer of material being fused to form the complete nonthermal plasma generator 100. Only a portion of the nonthermal plasma generator 100 is therefore formed during step 710 of the method. This portion may correspond to the end cap 600 and the interconnected array of electrodes 210 as described above.
  • this portion may correspond to the end cap 600 and a portion of the interconnected array of electrodes 210, such as half, a third or a quarter of the interconnected array of electrodes 210.
  • this portion may correspond to the end cap 600, the interconnected array of electrodes 210 and a portion of the inlet 500.
  • one or more components are inserted into the nonthermal plasma generator. For example, a dielectric material may be inserted into the separation between the electrodes in each pair of electrodes as described above.
  • the nonthermal plasma generator 100 comprising the interconnected array of electrodes 210 illustrated in Figure 6
  • build of the nonthermal plasma generator 100 is stopped at a location corresponding to the first end of the first electrode 202 of each pair of electrodes 200 which are connected to the nest 400 prior to build of the nest 400.
  • the nonthermal plasma generator 100 is built in the build direction z, where the build direction is along the length of the elongate wires of the first electrodes 202 until the first end of the first electrodes 202 is reached, such that the entire first electrode and second electrode has been built.
  • the build of the nonthermal plasma generator 100 may be stopped at a different location, for example corresponding to halfway along the build of the electrodes, and then one or more components, such as a dielectric material 300 inserted.
  • the one or more components inserted into the nonthermal plasma generator 100 may include one or more sensor components, such as a strain gauge, a thermocouple, pressure sensor or a current sensor, and/or one or more monitoring components, such as a microphone or camera.
  • sensor and monitoring components may be fixed or adhered by any conventional means to a surface of the nonthermal plasma generator 100, such as one of the electrodes 202, 204 or a surface of the hollow portion 504 of the inlet 500. This allows sensor components and/or monitoring components to be placed within fully enclosed regions of the nonthermal plasma generator 100 which would not be accessible once build of the nonthermal plasma generator 100 had ended; in other words once the complete nonthermal plasma generator 100 has been formed using the additive manufacture process.
  • step 740 build of the nonthermal plasma generator is continued.
  • build of the nonthermal plasma generator resumes with the next layer after the most recently formed layer prior to stopping the build.
  • the complete nonthermal plasma generator 100 is then formed, but containing one or more additional components that were inserted into the nonthermal plasma generator 100 during the build process.
  • metal powder 188 is removed from inside the nonthermal plasma generator 100 between steps 720 and 730 of the method; in other words after stopping the build of the nonthermal plasma generator 100 but before the one or more components are inserted into the nonthermal plasma generator 100.
  • the metal powder 188 is then inserted back into the nonthermal plasma generator 100 between steps 730 and 740; in other words after the one or more components are inserted into the nonthermal plasma generator 100 but before continuing the build of the nonthermal plasma generator 100. This makes it easier to insert the one or more components into the nonthermal plasma generator 100, since at step 720 when the build is stopped, the nonthermal plasma generator 100 is immersed in the powder bed 180.
  • Removing the metal powder 188 allows the nonthermal plasma generator 100 to be kept in the powder bed 180 until build of the nonthermal plasma generator 100 continues. Although this is not essential, if the nonthermal plasma generator 100 is removed from the powder bed 180, additional setup steps are required before build of the nonthermal plasma generator 100 continues since the nonthermal plasma generator 100 needs to be located and orientated correctly on the powder bed 180 ensure that the continuation of the build of the nonthermal plasma generator 100 occurs correctly.
  • the nonthermal plasma generator 100 comprises one or more sacrificial tubes extending from a lower portion of the nonthermal plasma generator 100 in the build direction z, such as the end cap 600 to the top of the powder bed 180.
  • the top of the sacrificial tube is in line with the top of the nonthermal plasma generator 100 in the build direction z when build of the nonthermal plasma generator 100 is stopped.
  • Suction or pressure can be applied to the top of the sacrificial tube at the top of the powder bed 188 in order to force metal powder 188 out of the nonthermal plasma generator 100.
  • a sacrificial tube is not required on the completed nonthermal plasma generator 100, it can be removed after build of the nonthermal plasma generator 100 has been completed.
  • Figure 14 shows a method 800 for manufacturing a nonthermal plasma generator.
  • a computer automated design (CAD) file is obtained.
  • the CAD file provides a data structure which represents the design of a nonthermal plasma generator 100 comprising a plurality of electrodes 202, 204 arranged in at least one pair 200 as discussed above.
  • obtaining the CAD file at step 810 may comprise a designer generating a three- dimensional (3D) model of the nonthermal plasma generator from scratch, or could comprise reading an existing design from a recording medium or obtaining the CAD file via a network.
  • the design file may represent the 3D geometry to be manufactured.
  • the CAD file is converted to instructions for supplying to an additive manufacturing machine.
  • the instructions control the additive manufacturing machine to deposit or form respective layers of material, which are built up layer by layer to form the overall nonthermal plasma generator.
  • the 3D design represented by the CAD file may be sliced into layers each providing a two-dimensional representation of the material to be formed in the corresponding layer.
  • the instructions may also specify particular settings for the additive manufacturing machine in order to further control the separation between the electrodes in each pair of electrodes, such as laser parameters or a scanning speed or interval between formation of successive layers.
  • the design may include each of these parts in a single design file or body.
  • the design may include each of these parts as separate design files as described above.
  • the design may include a separate CAD file for each of the inlet 500, the interconnected array of electrodes 210, and the end cap 600.
  • the nonthermal plasma generator 100 comprises three separate CAD file, the nonthermal plasma generator 100 can still be formed as a single integrated mass of material, for example using the method as described above in reference to Figure 13 where the build of nonthermal plasma generator 100 is stopped during the build of the nonthermal plasma generator and then continued again.
  • each of the inlet 500, the interconnected array of electrodes 210, and the end cap 600 may be manufactured as separate parts and then assembled to form the nonthermal plasma generator 100.
  • the build direction z for each of the inlet 500, the interconnected array of electrodes 210, and the end cap 600 may be different and selected based on particular design constrains of each part, such as the presence of overhangs as described above.
  • the interconnected array of electrodes 210 and the end cap 600 may be manufactured as a single part and the inlet 500 manufactured as a separate part and then later assembled together. As described above, the nest 400 may form part of the interconnected array of electrodes 210 or the inlet 500.
  • the interconnected array of electrodes 210 may be formed using the method 700 as described above with reference to Figure 13, where the tubes of dielectric material are inserted in the separation between the first electrode and the second electrode of each pair of electrodes prior to the build of the nest 400.
  • the converted instructions are supplied to an additive manufacturing machine which manufactures the nonthermal plasma generator as an integrated mass of consolidated material using additive manufacture, for example using the method 700 as described above with reference to Figure 13.
  • the nonthermal plasma generator can be made from various materials, e.g. metals or alloys, such as titanium or stainless steel, or a polymer for example.
  • Various forms of additive manufacturing can be used, but in one example the additive manufacture uses selective laser melting.

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Abstract

A method of manufacturing a nonthermal plasma generator (100), where the nonthermal plasma generator (100) is built as an integrated mass of material using an additive manufacture process, the nonthermal plasma generator (100) including a plurality of electrodes (202, 204) arranged in at least one pair (200), wherein a separation (206) between the electrodes (202, 204) in each pair of electrodes (200) is controlled by the additive manufacture process.

Description

NONTHERMAL PLASMA GENERATOR AND METHOD OF MANUFACTURING THE
SAME
The present technique relates to the field of plasma generators, in particular nonthermal plasma generators and methods for their manufacture.
Nonthermal plasma, also referred to as cold plasma or non-equilibrium plasma, is a particular type of plasma that is not in thermodynamic equilibrium, since the electron temperature is much hotter than the temperatures of the ions and neutrals. Nonthermal plasma is typically produced in low pressure discharges or in short pulse discharged such as Dielectric Barrier Discharges (DSD) or nanosecond discharges.
Nonthermal plasma generators have a variety of applications, such as reducing the emission of nitrogen oxides in the exhaust gases of diesel automotive engines. Additionally, in the case of dual-fuel automotive engines, nonthermal plasma generators can be used to reduce the amount of methane in the exhaust gases. In such applications, collisions between the hot electrons in the plasma and the cold gas molecules lead to dissociation reactions and the formation of radicals. The presence of a catalyst, such as platinum or rhodium, can further enhance the conversion of reactants in order to alter the chemical composition of the gas in the exhaust.
Another automotive application for such nonthermal plasma generators is for hydrocarbon reforming in fuel cell systems. Since no infrastructure for distributing hydrogen currently exists, there has been a focus on on-board, in other words in vehicle, hydrogen generation from hydrocarbon reforming, where hydrogen is produced directly from gasoline or petrol. Traditional approaches to hydrogen reforming use catalysers to create radical species to enhance the reaction used to generate the hydrogen, but the catalysers can be rapidly contaminated by sulphur contained in the fuel or by carbon deposit. Nonthermal plasma generators provide a means to reform fuel to produce hydrogen which eliminates the problems encountered in the catalytic reformers.
Nonthermal plasma generators for such automotive applications can be designed to be retrofitted into an existing exhaust system, so must conform to the dimensions of the exhaust. Accordingly, there is a need to provide smaller, more efficient nonthermal plasma generators and means to manufacture such nonthermal plasma generators in order to provide more plasma for a given size of nonthermal plasma generator or a given input energy.
At least examples provide a method of manufacturing a nonthermal plasma generator, wherein the nonthermal plasma generator is built as an integrated mass of material using an additive manufacture process, the nonthermal plasma generator including a plurality of electrodes arranged in at least one pair, wherein a separation between the electrodes in each pair of electrodes is controlled by the additive manufacture process.
At least some examples provide nonthermal plasma generator built using the method of manufacture as discussed above.
At least some examples provide a nonthermal plasma generator built as an integrated mass of material using an additive manufacture process, the nonthermal plasma generator comprising a plurality of electrodes arranged in at least one pair, wherein a separation between the electrodes in each pair of electrodes is controlled by the additive manufacture process.
At least some examples provide an exhaust gas processing system comprising the nonthermal plasma generator as discussed above or a fuel cell system comprising the nonthermal plasma generator as discussed above.
At least some examples provide a computer-readable data structure representing a design of a nonthermal plasma generator as discussed above. At least some examples provide a computer-readable data structure representing machine instructions which, when performed by an additive manufacturing machine, cause the additive manufacture machine to perform the method of manufacture as discussed above. In each case, the data structure may be stored on the storage medium. The storage medium may be a non-transitory storage medium.
Further aspects, features and advantages of the present technique will be apparent from the following description of examples, which is to be read in conjunction with the accompanying drawings, in which:
Figure 1 schematically illustrates an example of a non-thermal plasma generator;
Figures 2 and 3 schematically illustrate a cross-section through one pair of electrodes of the nonthermal plasma generator;
Figure 4 schematically illustrates an interconnected array of electrodes of a non thermal plasma generator;
Figure 5 schematically illustrates a cross-section through an interconnected array of electrodes of a non-thermal plasma generator;
Figure 6 schematically illustrates an interconnected array of electrodes of a non thermal plasma generator;
Figure 7 schematically illustrates a cross-section through an interconnected array of electrodes of a non-thermal plasma generator;
Figure 8 schematically illustrates a further example of an interconnected array of electrodes of a non-thermal plasma generator;
Figure 9 schematically illustrates an inlet of a nonthermal plasma generator; Figure 10 schematically illustrates a cross-section through an inlet of a nonthermal plasma generator;
Figure 11 schematically illustrates an exploded view of components of a nonthermal plasma generator;
Figure 12 shows one example of manufacturing equipment for manufacturing the nonthermal plasma generator by additive manufacture;
Figure 13 is a flow diagram illustrating a method of manufacturing a nonthermal plasma generator;
Figure 14 is a flow diagram illustrating a method of manufacturing a nonthermal plasma generator;
A method of manufacturing a nonthermal plasma generator is provided wherein the nonthermal plasma generator is built as an integrated mass of material using an additive manufacture process. The nonthermal plasma generator includes a plurality of electrodes arranged in at least one pair. This beneficially allows the nonthermal plasma generator to be manufactured as a single part, and in particular allows the electrodes to be manufactured as part of the same integrated mass of material as the remainder of the nonthermal plasma generator. In other words, the nonthermal plasma generator can be manufactured as a single part without having to separately manufacture the electrodes and assemble them later. This results in fewer parts needing to be manufactured and fewer assembly steps. Combining the electrodes into the same integrated mass of material also reduces the amount of arcing in the nonthermal plasma generator, since the electrodes are made of the same material and there are no discontinuities or joins, such as weld lines. Such discontinuities or joins would create changes in materials or surface finish which can promote arcing. Providing a nonthermal plasma generator with integral electrodes therefore reduces arcing, which in turn increases the amount of plasma that can be produced for a given input energy.
A separation between the electrodes in each pair of electrodes is controlled by the additive manufacture process. In other words, because the electrodes are formed as part of the same integrated mass of material as the remainder of the nonthermal plasma generator, the position and location of the electrodes within the nonthermal plasma generator is a result of the manufacture using the additive manufacture process. The separation between each electrode in each pair of electrodes, in other words the distance between each electrode in each pair of electrodes, is maintained by controlling the additive manufacture process to ensure the completed nonthermal plasma generator has the intended separation between the electrodes. The surface finish of the electrodes can be controlled by the additive manufacture process, which in turn controls the separation between the electrodes and reduces the amount of arcing in the nonthermal plasma generator. In some examples the nonthermal plasma generator comprises a dielectric material inserted in the separation between the electrodes in each pair of electrodes. The dielectric material acts as an electric insulator between the electrodes in each pair of electrodes, thereby preventing arcing of the electrodes.
In some examples a first electrode in each pair of electrodes comprises an elongate wire. In some examples each of the elongate wires has a diameter of between 1mm and 2mm. This increases the surface area of the first electrode whilst providing a small volume of material. In some examples the elongate wires are parallel with one another. This increases the packing density of the electrodes, thereby allowing more electrodes to be arranged in a fixed volume. In some examples a build direction of the additive manufacture process is along a length of the elongate wires. Elongate structures can be unstable during the additive manufacture process as they are only supported at one end. Building the nonthermal plasma generator along the length of the elongate wires, in other words along the long axis of the wire, provides better control and a better surface finish for the electrodes, thereby providing better control of the separation between the electrodes and reducing arcing.
In some examples a second electrode in each pair of electrodes comprises a tube portion surrounding the first electrode, and for each pair of electrodes the separation controlled by the additive manufacture process is between the first electrode and the tube portion of the second electrode. In other words, each pair of electrodes comprises a tube portion with an elongate wire electrode passing along the tube portion. As discussed above, this reduces the overall size and volume of the electrode pair, since the first electrode is located inside the tube portion of the second electrode. This allows the separation between the first electrode and the second electrode to be controlled during manufacture since both electrodes are formed as part of the additive manufacture process. This increases the amount of plasma that can be created for a given size of nonthermal plasma generator and/or for a given input energy.
In some examples the nonthermal plasma generator comprises a plurality of pairs of electrodes, and the second electrodes in each pair of electrodes are arranged to form an interconnected array of electrodes. In other words, all of the second electrodes are grouped together such that they form a single mass of material, thereby reducing the separation between each pair of electrodes and increasing the density of electrodes. In other words, more electrodes can be contained within a fixed volume.
In some examples, for each pair of electrodes, the first electrode is positioned substantially along a centre of the tube portion of the second electrode. This means the separation between the first electrode and the second electrode is substantially the same around the circumference of the tube portion of the second electrode, which results in a more even distribution of plasma in the tube portion of the second electrode.
In some examples the nonthermal plasma generator comprises a tube of dielectric material in the separation between the first electrode and the second electrode of each pair of electrodes. As discussed above, this acts as an electric insulator between the electrodes in each pair of electrodes, thereby preventing arcing of the electrodes. At the same time, the dielectric material can be contained within the tube portion of the second electrode, such that the external volume or shape of the pair of electrodes is not increased due to the inclusion of the dielectric material. Tubes of dielectric material are also easier to coat with a catalyst or other surface coating than a more complex structure, in particular since the catalyst coating may be particularly thin, for example 50 to 100 pm.
In some examples each tube of dielectric material is configured such that a separation between the tube of dielectric material and the first electrode is greater than a separation between the tube of dielectric material and the second electrode for each pair of electrodes. This means the dielectric material is located closer to the second electrode, thereby increasing the amount of gas that can be contained between the dielectric material and the first electrode, thereby ensuring that the majority of the plasma is generated between the first electrode and the dielectric material whilst increasing the amount of gas that can flow in the separation between the first electrode and the dielectric material.
In some examples the nonthermal plasma generator comprises an inlet to direct a gas into the separation between the electrodes in each pair of electrodes. This ensures that gas is able to flow into the separation between the electrodes in each pair of electrodes, so that the gas in the separation between the electrodes in each pair of electrodes can be ionised to form plasma. In some examples the inlet comprises a mesh. The mesh creates a more even distribution of gas into each pair of electrodes. In other words, the gas flow into the separation between the electrodes in each pair of electrodes is substantially the same for each pair of electrodes.
In some examples the nonthermal plasma generator comprises a nest connected to a first end of the first electrode of each pair of electrodes, wherein the nest is configured to provide a voltage to each of the first electrodes from an external supply. This allows each of the first electrodes to be provided with voltage from the same external supply, whilst also allowing the nest to be integrally formed with the first electrodes.
In some examples the method of manufacture comprises starting the build of the nonthermal plasma generator using the additive manufacture process, stopping the build of the nonthermal plasma generator prior to the end of the build, inserting one or more components into the nonthermal plasma generator and continuing the build of the nonthermal plasma generator. In this manner, an additional component can be inserted into the nonthermal plasma generator during the manufacture of the nonthermal plasma generator, thereby allowing the additional component to be added in a location entirely contained within the nonthermal plasma generator which is not otherwise accessible once the nonthermal plasma generator is fully manufactured. This provides greater design scope for nonthermal plasma generator, since the location of additional components is not limited by access constraints of the manufactured nonthermal plasma generator. The additional component can be entirely contained within the nonthermal plasma generator, and even inside a wall of the nonthermal plasma generator.
In some examples the one or more components are formed of a dielectric material and in some examples a component of the one or more components is inserted in the separation between the electrodes in each pair of electrodes. As described above, the dielectric material can be used to prevent arcing of the electrodes. By stopping the build and inserting the dielectric component in the separation between the electronics, a more complex electrode geometry can be formed since the dielectric material can be added during manufacture of the electrodes rather than afterwards.
The additive manufacture process may be controlled by supplying an electronic design file which represents characteristics of the design to be manufactured, and inputting the design file to a computer which translates the design file into instructions supplied to the manufacturing device. For example, the computer may slice a three-dimensional design into successive two-dimensional layers, and instructions representing each layer may be supplied to the additive manufacture machine, e.g. to control scanning of a laser across a powder bed to form the corresponding layer. Hence, in some embodiments rather than providing a physical nonthermal plasma generator, the technique could also be implemented in a computer-readable data structure which represents the design of a nonthermal plasma generator as discussed above. In some examples, the computer-readable data structure comprises a computer automated design (CAD) file. Thus, rather than selling the nonthermal plasma generator in its physical form, it may also be sold in the form of data controlling an additive manufacturing machine to form such a nonthermal plasma generator. A storage medium may be provided storing the data structure.
Figure 1 schematically illustrates an example of a non-thermal plasma generator 100. The nonthermal plasma generator 100 is built as an integrated mass of material using an additive manufacture process.
The nonthermal plasma generator 100 includes a plurality of electrodes arranged in at least one pair. Figure 2 schematically illustrates a cross-section through one pair of electrodes 200 of the nonthermal plasma generator 100. The pair of electrodes comprises a first electrode 202 and a second electrode 204. There is a separation 206 between the first electrode 202 and the second electrode 204 in the pair of electrodes 200, and the separation 206 controlled by the additive manufacture process. In other words, the distance between the first electrode 202 and the second electrode 204 in each pair of electrodes 200 is maintained during manufacture process by controlling the additive manufacture process. This is in contrast to existing methods where one or more of the electrodes are added to the nonthermal plasma generator after manufacture of the nonthermal plasma generator, creating additional assembly steps. In the nonthermal plasma generator 100 illustrated in Figure 1 , all of the electrodes are formed as part of the same integrated mass of material, and therefore the separation 206 between the electrodes 202, 204 must be maintained, in other words controlled, during the manufacture of the nonthermal plasma generator 100.
In the example illustrated in Figure 2, the first electrode 202 in each pair of electrodes 200 comprises an elongate wire. In other words, the first electrode 202 is a slender body with a length several times greater than its width. For example, if the elongate wire has a circular cross-section, the diameter of the wire may be between 1 mm and 2mm whilst the length of the wire is between 10 and 50mm. In the case of the pair of electrodes 200 illustrated in Figures 2 and 3, the cross-section is taken through the width or diameter of the elongate wire in a direction perpendicular the length of the elongate wire. Although the first electrode in Figures 2 has a circular cross-section, it will be appreciated that the first electrode may comprise an elongate wire with any shape of cross-section, such as a rectangle, triangle, polygon, ellipse or crescent shaped.
In the example illustrated in Figure 2, the second electrode 204 in each pair of electrodes 200 comprises a tube portion surrounding the first electrode. In other words, the second electrode 204 has a hollow portion, and the first electrode passes through or is at least partially contained within the hollow portion of the second electrode 204. In such a case, for each pair of electrodes, the separation between the first electrode 202 and the tube portion of the second electrode 204 is controlled by the additive manufacture process.
In the example illustrated in Figure 2, the first electrode 202 is positioned substantially along a centre of the tube portion of the second electrode 204. In this example, as the first electrode 202 has a circular cross-section and the tube portion of the second electrode 204 has a circular cross-section, this results in the separation 206 between the first electrode 202 and the second electrode 204 being substantially the same around the circumference of the first electrode 202 and the tube portion of the second electrode 204. This results in a more even distribution of gas around the first electrode, thereby facilitating a more even plasma distribution in the separation 206 between the first electrode 202 and the second electrode 204. It will be appreciated, however, that the first electrode 202 may be located anywhere within the tube portion of the second electrode 204, thereby providing a difference in separation 206 around the circumference of the first electrode 202 and the tube portion of the second electrode 204. This is beneficial in applications where a variation in gas and plasma distribution in the separation 206 between the first electrode 202 and the second electrode 204 is desired. It will be appreciated, however, that although the tube portion of the second electrode in Figure 2 has a circular cross-section, the tube portion of the second electrode may have any shape of cross-section, such as a rectangle, triangle, polygon, ellipse or crescent shaped.
Although in the example illustrated in Figure 2 the first electrode 202 comprises an elongate wire and the second electrode 204 comprises a tube portion surrounding the elongate wire, it will be appreciated that the pair of electrodes 200 may be formed of any shape. For example, the first electrode 202 and the second electrode 204 may each be a flat plate arranged parallel to one another so as to provide a constant separation 206 between the pair of electrodes 200. Equally, the first electrode 202 and the second electrode 206 may not be parallel to each other, thus creating a varying separation between the electrodes for applications where such a variation in gas and plasma distribution in the separation between the electrodes is desired. The first electrode 202 and the second electrode 204 may both comprise elongate wires, or the first electrode 202 may comprise an elongate wire whilst the second electrode 204 comprises a flat plate. It will therefore be appreciated that the first electrode 202 and the second electrode 204 may be any shape, and the shape of the first electrode and the second electrode need not be the same.
In some examples, the nonthermal plasma generator 100 comprises a dielectric material inserted in the separation 206 between the electrodes 202, 204 in each pair of electrodes 200. In other words, a material is inserted between the first electrode 202 and the second electrode 204 of each pair of electrodes 200 to act as an electrical insulator between the first electrode 202 and the second electrode 204, thereby preventing arcing of any gas between the pair of electrodes 200. This is shown in Figure 3, which schematically illustrates the same cross-section through a pair of electrodes 200 as illustrated in Figure 2, but with a dielectric material 300 inserted in the separation 206 between the first electrode 202 and the second electrode 204 in the each pair of electrodes 200. The dielectric material 300 may be a ceramic material, such as aluminium oxide, or any other material with good electrical insulator properties. The dielectric material 300 may also be coated in one or more catalysts, such as platinum or rhodium, in order to enhance the conversion of reactants in the plasma generator in order to alter the chemical composition of the gas proximate to the electrodes, particular in the automotive engine exhaust applications as described above.
In the example illustrated in Figures 2 and 3, where the first electrode 202 of the pair of electrodes 200 comprises an elongate wire and the second electrode 204 of the pair of electrodes 200 comprises a tube portion surrounding the first electrode 202, the dielectric material 300 is a tube of dielectric material in the separation 206 between the first electrode 202 and the second electrode 204. In other words, the dielectric material 300 passes through or is at least partially contained within the hollow portion of the second electrode 204, and the dielectric material 300 also has a hollow portion that the first electrode passes through or is at least partially contained within. The tube of dielectric material 300 therefore surrounds the first electrode 202, and the tube of the second electrode 204 surrounds both the dielectric material 300 and the first electrode 202 so that the dielectric material 300 is between the first electrode 202 and the second electrode 204.
In the example illustrated in Figure 3, the tube of dielectric material 300 is configured such that a separation 302 between the tube of dielectric material 300 and the first electrode 202 is greater than a separation 304 between the tube of dielectric material 300 and the second electrode 204. As shown in Figure 3, this allows for a larger volume of gas between the tube of dielectric material 300 and the first electrode 202 than between the tube of dielectric material 300 and the second electrode 204. In some examples, there is no separation 304 between the tube of dielectric material 300 and the second electrode 204, such that the dielectric material 300 is in contact with the second electrode 204. In this case, the only volume of gas in the separation 206 between the first electrode 202 and the second electrode 204 is in the separation 302 between the tube of dielectric material 300 and the first electrode 202.
Although in Figure 3 the dielectric material 300 is a tube, it will be appreciated that the dielectric material 300 may be any shape suitable to be located in the separation between the first electrode 202 and the second electrode 204. For example, where the first electrode 202 and the second electrode 204 are parallel flat plates, the dielectric material 300 may then also be a flat plate inserted parallel to the first electrode 202 and the second electrode 204 in the separation 206 between the pair of electrodes 200.
Although Figures 2 and 3 illustrate a single pair of electrodes 200, it will be appreciated that the nonthermal plasma generator 100 may comprise multiple pairs of electrodes, for example 2, 10, 12, 50 or more. In other words, the nonthermal plasma generator 100 comprises a plurality of pairs of electrodes 200.
Figure 4 illustrates an example of an interconnected array of electrodes 210 of a non thermal plasma generator, for example the nonthermal plasma generator 100 illustrated in Figure 1. Figure 5 then illustrates a cross-section through the interconnected array of electrodes 210 of a non-thermal plasma generator 100, the cross-section being taken through the section A-A as shown in Figures 1 and 4. As shown in Figures 4 and 5, there are a plurality of pairs of electrodes, for example those described above with reference to Figures 2 and 3. The second electrodes 204A, 204B, 204N in each pair of electrodes are arranged to form the interconnected array of electrodes 210. In other words, the second electrodes 204A, 204B, 204N in each pair of electrodes are arranged to form a single mass of material where each of the second electrodes 204A, 204B, 204N is connected to at least one other second electrode. Although in the example illustrated in Figures 4 and 5 there is a gap 208 between the second electrodes, this is not essential and it will be appreciated that the second electrodes 204A, 204B, 204N in each pair of electrodes may be arranged such that the only space or gap available for gas to pass through the interconnected array of electrodes 210 is in the tube portion of each of the second electrodes 204A, 204B, 204N. Equally, the gap 208 may be sealed at one or both ends of the tube portion of the second electrodes 204A, 204B, 204N such that, although there are still one or more gaps 208 in the interconnected array of electrodes 210, gas is unable to follow into the one or more gaps 208. This reduces the mass of the part whilst ensuring that all of the gas passes in the tube portion of each of the second electrodes 204A, 204B, 204N.
As illustrated in Figures 4 and 5, the first electrodes 202A, 202B, 202N each comprise elongate wire, and the elongate wires are arranged in parallel with one another. In other words, the first electrodes 202A, 202B, 202N are arranged such that the elongate wires are orientated in substantially the same direction, such that the elongate or long axis of each wire is aligned with the elongate or long axis of each other wire. In the example illustrated in Figure 4 this is orientated with the z axis. As illustrated in Figure 4, the tube portion of each second electrode 204A, 204B, 204N is then also aligned such that the elongate or long axis of each tube is aligned with the elongate or long axis of each other tube, such that the interconnected array of electrodes 210 forms an elongate bundle of pairs of electrodes.
Figures 6 and 7 correspond, respectively, to Figures 4 and 5, but illustrate an example where a dielectric material 300A, 300B, 300N is inserted in the separation 206A, 206B, 206N between the electrodes in each pair of electrodes. As illustrated in Figure 6, the dielectric material 300A, 300B, 300N is a tube inserted in the separation between the elongate wire first electrodes 202A, 202B, 202N and the tube portions of each second electrode 204A, 204B, 204N. As described above, the separation between each tube of dielectric material 300A, 300B, 300N and each first electrode 202A, 202B, 202N may be greater than the separation between each tube of dielectric material 300A, 300B, 300N and each second electrode204A, 204B, 204N, but this is not essential. For example, the location of the tube of dielectric material 300 within the separation 206 between the first electrode 202 and the second electrode 204 may be different for one or more pairs of electrodes 200.
Although Figures 4 to 7 illustrate multiple pairs of identical electrodes, the shape and size of the electrodes in each pair of electrodes need not be the same. For example, each pair of electrodes may comprise an elongate wire and a tube portion surrounding the elongate wire, but the diameters of the elongate wire and the tube portion may be different for each pair of electrodes. Additionally, one pair of electrodes may comprise an elongate wire and a tube portion surrounding the elongate wire whilst another pair of electrodes comprises a pair of parallel flat plates.
The interconnected array of electrodes 210 may take also take any shape. Although in Figures 4 to 7 the second electrodes 204A, 204B, 204N in each pair of electrodes are arranged to form an interconnected array of electrodes 210 in the shape of a grid of electrodes, it will be appreciated that this is not essential. For example, the second electrodes 204A, 204B, 204N in each pair of electrodes may be arranged to form a linear interconnected array of electrodes 210, where each second electrode 204 is only in directed contact with up to 2 other second electrodes 204 on opposite sides of each second electrode 204. Alternative, the second electrodes 204A, 204B, 204N in each pair of electrodes may be arranged to form a ring shaped interconnected array of electrodes 210. The grid shaped interconnected array of electrodes 210 illustrated in Figures 4 to 7 advantageously maximises the number of pairs of electrodes that can be contained within a fixed volume for the interconnected array of electrodes 210. In other words, the packing density of the pairs of electrodes within the interconnected array of electrodes 210 is maximised. The grid shaped interconnected array of electrodes 210 may be of any configuration depending on the number of pair of electrodes, such as 3x3, 2x3 or 3x4 as illustrated in Figures 4 to 7.
Figure 8 illustrates a further example of an interconnected array of electrodes 210 of a non-thermal plasma generator 100, but further comprising a nest 400. The interconnected array of electrodes 210 may correspond to the interconnected array of electrodes 210 illustrated in Figures 4 and 6. The nest 400 is connected to first end of the first electrode 202 of each pair of electrodes. In the example illustrated in Figure 8, this corresponds to an end of the elongate wire of each of the first electrode, in other words an end of the elongate or long axis of the elongate wire. The nest 400 is configured to provide a voltage to each of the first electrodes 202 from an external supply. In other words, the nest provides a means of interconnecting each of the first electrodes 202 such that all of the first electrodes 202 can be provided a voltage from the same external supply. In one example, the external supply provides a 14kV voltage to the first electrodes 202. The external supply can supply the voltage as a continuous voltage or as pulses as described above. For example, the voltage can be supplied as pulses with duration of the order of nanoseconds with the peak voltage of each pulse being of the order of kilovolts. It will be appreciated, however, that the exact form of the supplied voltage can be adapted for the specific application of the nonthermal plasma generator 100.
As illustrated in Figure 8, the nest 400 is formed of a plurality of interconnected wires, but this is not essential. For example, the nest 400 may be a flat plate connected to the first end of the first electrode 202 of each pair of electrodes. The nest illustrated in Figure 8 comprises a top-hat 402 at the location where the nest connects to each first electrode 202. As described below, this helps to ensure a solid connection between each first electrode 202 and the nest 400 during the additive manufacturing process and allows the nest 400 to be manufactured separately from the first electrodes, but this is not essential. In an alternative example, the nest does not comprise any top-hats 402, such that the nest 400 provides a smooth continuation of each elongate wire. In this example, the plurality of interconnected wires forming the nest 400 may have substantially the same diameter as the elongate wires forming the first electrodes 202.
The plurality of interconnected wires may also comprise one or more peaks 404 which provide a curve in the wire in a direction away from the first electrodes 202 and, as a result, the second electrodes 204. This increases the separation between the wires of the nest 400 and the second electrodes 204, thereby preventing arcing between the nest 400 and the second electrodes 204 since the separation between the nest 400 and the second electrodes 204 will be greater than the separation between the first electrode 202 and the second electrode 204 in each pair of electrodes 200. As illustrated in Figures 6 and 8, the first electrode 202 in each pair of electrodes 200 may be configured to extend beyond the tube portion of the second electrode 204 to ensure that the separation 206 between the first electrode 202 and the second electrode 204 in each pair of electrodes 200 is at a minimum within the tube portion of the second electrode 204.
Although not shown in Figure 8, the nonthermal plasma generator 100 may also comprise a second nest connected to a second end of the first electrode 202 of each pair of electrodes. For example, the second end may be the end of the elongate wire opposite the first end connected to the first nest 400, such that there is a nest at each end of each elongate wire. The second nest may be identical and comprise the same features as the first nest, but this is not essential and the second nest may take any form suitable to provide a connection to the second end of first electrode of each pair of electrodes.
In some examples, the nonthermal plasma generator comprises an inlet. Figure 9 schematically illustrates an example of such an inlet 500 of a nonthermal plasma generator 100. The inlet directs a gas, such as an exhaust gas from an automotive engine, into the separation 206 between the electrodes 202, 204 in each pair of electrodes 200. In the example illustrated in Figure 9, the inlet is located at a first end of the interconnected array of electrodes 210 described above. The gas enters the inlet through an orifice 502, and is directed by the inlet into the separation 206 between the electrodes in each pair of electrodes of the interconnected array of electrodes 210. The inlet 500 is configured such that all of the gas entering the orifice 502 is directed into the separation 206 between the electrodes in each pair of electrodes 200. The first end of the interconnected array of electrodes 210 where the inlet 500 is located may correspond to the first end of the first electrode 202 of each pair of electrodes 200 where the nest 400 is located as described above with reference to Figure 8.
Figure 10 schematically illustrates a cross-section through the inlet 500 of a nonthermal plasma generator, where the cross-section is taken through the section B-B illustrated in Figure 9. The inlet 500 comprises a hollow portion 504 which allows the gas to flow from the orifice 502 into the separation 206 between the electrodes in each pair of electrodes. The velocity of the gas entering the inlet 500 may be of the order of 20 litre per minute. Accordingly, the hollow portion 504 of the inlet 500 acts as a plenum or volume to reduce the velocity of the gas before the gas enters the separation 206 between the electrodes in each pair of electrodes. This increases the efficiency of the nonthermal plasma generator since more reactions within the gas, and therefore more changes in the chemical composition of the gas can occur as the gas travels along the separation 206 between the electrodes in each pair of electrodes.
In the example where the first end of the interconnected array of electrodes 210 where the inlet 500 is located corresponds to the first end of the first electrode 202 of each pair of electrodes 200 where the nest 400 is located as described above with reference to Figure 8, the nest 400 is located within the hollow portion 504 of the inlet 500. Accordingly, the nest 400 may form part of the inlet 500, or may form part of the interconnected array of electrodes 210.
The inlet 500 also comprises one or more voltage supply channels 506A, 506B through which the voltage from the external supply can be provided to the electrodes. For example, the voltage from the external supply may be supplied to the nest 400 located within the hollow portion 504 of the inlet 500, and therefore to each of the first electrodes 202.
The inlet also comprises a mesh 510. The mesh 510 introduces turbulence into the gas flowing into the inlet, which improves the distribution of gas within the hollow portion 504, thereby creating a more even distribution of gas into the separations between the electrodes in each pair of electrodes. In other words, the flow of gas around each of the first electrodes is substantially the same. In the example illustrated in Figure 10, the mesh 510 is located between the orifice 502 and the hollow portion 504 of the inlet.
Figure 11 schematically illustrates an exploded view of components of the nonthermal plasma generator 100 illustrated in Figure 1 and described above. The nonthermal plasma generator 100 comprises an inlet 500, interconnected array of electrodes 210, and an end cap 600. In use, the gas enters the inlet 500 through the orifice 502 (not shown), flows through the interconnected array of electrodes 210 by flowing along the separation between the electrodes in each pair of electrodes and into the end cap 600. Although not illustrated, the end cap 600 comprises a port for the gas to flow out of the nonthermal plasma generator 100, for example into the exhaust system of an automobile. The end cap 600 may also comprise one or more voltage supply channels through which a voltage can be removed from the nonthermal plasma generator 100, such as by connection to the second electrode 204 in each pair of electrodes. The end cap 600 may also contain a second nest connected to the second end of each of the first electrodes as described above.
Although Figure 11 illustrates an exploded view of the components of the nonthermal plasma generator 100, as described above the nonthermal plasma generator 100 may be built as an integrated mass of material. In this case, the inlet 500, the interconnected array of electrodes 210 and the end cap 600 all form a single part. Alternatively, the inlet 500, the interconnected array of electrodes 210 and the end cap 600 may be formed a three separate parts and assembled using conventional techniques such as bolted, welded or otherwise joined together. Where the inlet 500, the interconnected array of electrodes 210 and the end cap 600 are formed as three separate parts, the tubes of dielectric material 300 (if present) are inserted into the separation 206 prior to the inlet 500, the interconnected array of electrodes 210 and the end cap 600 being assembled together.
Figure 12 schematically illustrates an example of additive manufacture. In this example, laser fused metal powder 188 is used to form an article 4 such as the nonthermal plasma generator 100 described above. The article 4 is built in a build direction z by forming the article 4 layer-by-layer upon a lowering powder bed 180 on top of which thin layers of metal power to be fused are spread by a powder spreader 182 prior to being melted (fused) via a scanning laser beam provided from a laser 184. Each layer is melted or fused onto the layer below it by the scanning laser beam. In regions where there is no material for the article directly below where the current layer is being formed, or there is an overlap between the layer currently being formed and the layer below, the material properties of the article 4 in these regions is reduced. These regions are commonly referred to as ‘overhangs’, since then material added in the current layer is overhanging the material of the layers below it. For example, the surface roughness of the material in these regions may be greater, or the strength of the material in these regions may be reduced. In order to mitigate against the reduction in material properties, the article 4, such as the nonthermal plasma generator 100 as described above, can be designed so that the wall thickness of the part is increased in the regions as described above.
In the case of the nonthermal plasma generator 100 as described above, the build direction z of the additive manufacture process may be along a length of the elongate wires of the first electrode 202. In other words, the build direction is in the elongate or long axis of the elongate wires of the first electrode 202, as indicated by the direction z in Figures 1 , 4,6 and 11. This also assists in controlling the separation between the electrodes in each pair of electrodes during the additive manufacture process, since each layer used to form the first electrode and the second electrode is deposited directly on top of the previous layer of material. As a result, there are no overhangs during formation of the electrodes, and therefore the surface roughness of the material can be minimised and therefore the separation between the electrodes in each pair of electrodes maintained and controlled.
In the example of the nonthermal plasma generator 100 described above where the first electrode comprises an elongate wire, the thickness of the elongate wire may vary in the build direction z. In other words, the amount of material and number of layers used to create the elongate wire varies as the nonthermal plasma generator is built. For example, the elongate wire may have an initial thickness in the build direction z which is greater than the thickness of the elongate wire along the majority of the build direction z. In other words, the initial layers used to form the elongate wire may use more material than the remainder of the layers used to the form the elongate wire in order to provide additional support and strength to the elongate wire and prevent distortion of the elongate wire during the additive manufacture process. In examples where there are multiple first electrodes, each comprising elongate wires, each of the elongate wires may have this greater initial thickness for the same reasons as described above.
The scanning of the laser beam via the laser 184, and the lowering of the bed 180, are computer controlled by a control computer 186. The control computer 186 is in turn controlled by a computer program (e.g. computer data defining the article 4 to be manufactured). This article defining data is stored upon a computer readable non-transitory medium 198. Figure 12 illustrates one example of a machine which may be used to perform additive manufacture. Various other machines and additive manufacturing processes are also suitable for use in accordance with the present techniques, whereby a nonthermal plasma generator is manufactured with plurality of electrodes arranged in at least one pair as discussed above.
Figure 13 shows a method 700 for manufacturing a nonthermal plasma generator, such as the nonthermal plasma generator 100 described above. At step 710 build of the nonthermal plasma generator 100 using the additive manufacture process is started, for example the additive manufacture process described in relation to Figure 12 above. At step 720 build of the nonthermal plasma generator 100 is stopped prior to the end of the build. In other words, the additive manufacture process is stopped prior to the final layer of material being fused to form the complete nonthermal plasma generator 100. Only a portion of the nonthermal plasma generator 100 is therefore formed during step 710 of the method. This portion may correspond to the end cap 600 and the interconnected array of electrodes 210 as described above. Alternatively, this portion may correspond to the end cap 600 and a portion of the interconnected array of electrodes 210, such as half, a third or a quarter of the interconnected array of electrodes 210. Alternatively, this portion may correspond to the end cap 600, the interconnected array of electrodes 210 and a portion of the inlet 500. At step 730 one or more components are inserted into the nonthermal plasma generator. For example, a dielectric material may be inserted into the separation between the electrodes in each pair of electrodes as described above. In the case of the nonthermal plasma generator 100 comprising the interconnected array of electrodes 210 illustrated in Figure 6, build of the nonthermal plasma generator 100 is stopped at a location corresponding to the first end of the first electrode 202 of each pair of electrodes 200 which are connected to the nest 400 prior to build of the nest 400. In other words, the nonthermal plasma generator 100 is built in the build direction z, where the build direction is along the length of the elongate wires of the first electrodes 202 until the first end of the first electrodes 202 is reached, such that the entire first electrode and second electrode has been built. This allows the tubes of dielectric material 300 to be inserted in the separation 206 between the first electrode 202 and the second electrode 204 of each pair of electrodes 200 before the a nest 400 connecting to the first end of each first electrode 202 is built. The build of the nonthermal plasma generator 100 may be stopped at a different location, for example corresponding to halfway along the build of the electrodes, and then one or more components, such as a dielectric material 300 inserted.
The one or more components inserted into the nonthermal plasma generator 100 may include one or more sensor components, such as a strain gauge, a thermocouple, pressure sensor or a current sensor, and/or one or more monitoring components, such as a microphone or camera. Such sensor and monitoring components may be fixed or adhered by any conventional means to a surface of the nonthermal plasma generator 100, such as one of the electrodes 202, 204 or a surface of the hollow portion 504 of the inlet 500. This allows sensor components and/or monitoring components to be placed within fully enclosed regions of the nonthermal plasma generator 100 which would not be accessible once build of the nonthermal plasma generator 100 had ended; in other words once the complete nonthermal plasma generator 100 has been formed using the additive manufacture process.
At step 740 build of the nonthermal plasma generator is continued. In other words, build of the nonthermal plasma generator resumes with the next layer after the most recently formed layer prior to stopping the build. The complete nonthermal plasma generator 100 is then formed, but containing one or more additional components that were inserted into the nonthermal plasma generator 100 during the build process.
In some examples, metal powder 188 is removed from inside the nonthermal plasma generator 100 between steps 720 and 730 of the method; in other words after stopping the build of the nonthermal plasma generator 100 but before the one or more components are inserted into the nonthermal plasma generator 100. In such an example, the metal powder 188 is then inserted back into the nonthermal plasma generator 100 between steps 730 and 740; in other words after the one or more components are inserted into the nonthermal plasma generator 100 but before continuing the build of the nonthermal plasma generator 100. This makes it easier to insert the one or more components into the nonthermal plasma generator 100, since at step 720 when the build is stopped, the nonthermal plasma generator 100 is immersed in the powder bed 180. Removing the metal powder 188 allows the nonthermal plasma generator 100 to be kept in the powder bed 180 until build of the nonthermal plasma generator 100 continues. Although this is not essential, if the nonthermal plasma generator 100 is removed from the powder bed 180, additional setup steps are required before build of the nonthermal plasma generator 100 continues since the nonthermal plasma generator 100 needs to be located and orientated correctly on the powder bed 180 ensure that the continuation of the build of the nonthermal plasma generator 100 occurs correctly.
In some examples, the nonthermal plasma generator 100 comprises one or more sacrificial tubes extending from a lower portion of the nonthermal plasma generator 100 in the build direction z, such as the end cap 600 to the top of the powder bed 180. In other words, the top of the sacrificial tube is in line with the top of the nonthermal plasma generator 100 in the build direction z when build of the nonthermal plasma generator 100 is stopped. Suction or pressure can be applied to the top of the sacrificial tube at the top of the powder bed 188 in order to force metal powder 188 out of the nonthermal plasma generator 100. As such a sacrificial tube is not required on the completed nonthermal plasma generator 100, it can be removed after build of the nonthermal plasma generator 100 has been completed.
Figure 14 shows a method 800 for manufacturing a nonthermal plasma generator. At step 810 a computer automated design (CAD) file is obtained. The CAD file provides a data structure which represents the design of a nonthermal plasma generator 100 comprising a plurality of electrodes 202, 204 arranged in at least one pair 200 as discussed above. For example, obtaining the CAD file at step 810 may comprise a designer generating a three- dimensional (3D) model of the nonthermal plasma generator from scratch, or could comprise reading an existing design from a recording medium or obtaining the CAD file via a network. The design file may represent the 3D geometry to be manufactured.
At step 820 the CAD file is converted to instructions for supplying to an additive manufacturing machine. The instructions control the additive manufacturing machine to deposit or form respective layers of material, which are built up layer by layer to form the overall nonthermal plasma generator. For example, the 3D design represented by the CAD file may be sliced into layers each providing a two-dimensional representation of the material to be formed in the corresponding layer.
In the example of the nonthermal plasma generator 100, the instructions may also specify particular settings for the additive manufacturing machine in order to further control the separation between the electrodes in each pair of electrodes, such as laser parameters or a scanning speed or interval between formation of successive layers.
In the example of the nonthermal plasma generator 100 comprising the inlet 500, the interconnected array of electrodes 210, and the end cap 600, the design may include each of these parts in a single design file or body. Alternatively, the design may include each of these parts as separate design files as described above. For example, the design may include a separate CAD file for each of the inlet 500, the interconnected array of electrodes 210, and the end cap 600. Although in this case the nonthermal plasma generator 100 comprises three separate CAD file, the nonthermal plasma generator 100 can still be formed as a single integrated mass of material, for example using the method as described above in reference to Figure 13 where the build of nonthermal plasma generator 100 is stopped during the build of the nonthermal plasma generator and then continued again.
Alternatively, each of the inlet 500, the interconnected array of electrodes 210, and the end cap 600 may be manufactured as separate parts and then assembled to form the nonthermal plasma generator 100. In this case, the build direction z for each of the inlet 500, the interconnected array of electrodes 210, and the end cap 600 may be different and selected based on particular design constrains of each part, such as the presence of overhangs as described above. In another example, the interconnected array of electrodes 210 and the end cap 600 may be manufactured as a single part and the inlet 500 manufactured as a separate part and then later assembled together. As described above, the nest 400 may form part of the interconnected array of electrodes 210 or the inlet 500. In the case where the nest 400 forms part of the interconnected array of electrodes 210, the interconnected array of electrodes 210 may be formed using the method 700 as described above with reference to Figure 13, where the tubes of dielectric material are inserted in the separation between the first electrode and the second electrode of each pair of electrodes prior to the build of the nest 400.
At step 830 the converted instructions are supplied to an additive manufacturing machine which manufactures the nonthermal plasma generator as an integrated mass of consolidated material using additive manufacture, for example using the method 700 as described above with reference to Figure 13. The nonthermal plasma generator can be made from various materials, e.g. metals or alloys, such as titanium or stainless steel, or a polymer for example. Various forms of additive manufacturing can be used, but in one example the additive manufacture uses selective laser melting.
Although illustrative embodiments of the invention have been described in detail herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various changes and modifications can be effected therein by one skilled in the art without departing from the scope of the invention as defined by the appended claims.

Claims

1. A method of manufacturing a nonthermal plasma generator, wherein the nonthermal plasma generator is built as an integrated mass of material using an additive manufacture process, the nonthermal plasma generator including a plurality of electrodes arranged in at least one pair, wherein a separation between the electrodes in each pair of electrodes is controlled by the additive manufacture process.
2. The method of claim 1 , wherein the nonthermal plasma generator comprises a dielectric material inserting in the separation between the electrodes in each pair of electrodes.
3. The method of claim 1 or 2, wherein a first electrode in each pair of electrodes comprises an elongate wire.
4. The method of claim 3, wherein each of the elongate wires has a diameter of between 1mm and 2mm.
5. The method of claim 3 or claim 4, wherein the elongate wires are parallel with one another.
6. The method of claim 5, wherein a build direction of the additive manufacture process is along a length of the elongate wires.
7. The method of any one of claims 3 to 6, wherein a second electrode in each pair of electrodes comprises a tube portion surrounding the first electrode, and for each pair of electrodes the separation controlled by the additive manufacture process is between the first electrode and the tube portion of the second electrode.
8. The method of claim 7, wherein the nonthermal plasma generator comprises a plurality of pairs of electrodes, and the second electrodes in each pair of electrodes are arranged to form an interconnected array of electrodes.
9. The method of claim 7 or claim 8, wherein, for each pair of electrodes, the first electrode is positioned substantially along a centre of the tube portion of the second electrode.
10. The method any one of claims 7 to 9, wherein the nonthermal plasma generator comprises a tube of dielectric material in the separation between the first electrode and the second electrode of each pair of electrodes.
11 . The method of claim 10, wherein each tube of dielectric material is configured such that a separation between the tube of dielectric material and the first electrode is greater than a separation between the tube of dielectric material and the second electrode for each pair of electrodes.
12. The method of any one of claims 3 to 11 , wherein the nonthermal plasma generator comprises an inlet to direct a gas into the separation between the electrodes in each pair of electrodes.
13. The method of claim 12, wherein the inlet comprises a mesh.
14. The method of any one of claims 3 to 13, wherein the nonthermal plasma generator comprises a nest connected to a first end of the first electrode of each pair of electrodes, wherein the nest is configured to provide a voltage to each of the first electrodes from an external supply.
15. The method of any one of the preceding claims, comprising: starting the build of the nonthermal plasma generator using the additive manufacture process; stopping the build of the nonthermal plasma generator prior to the end of the build; inserting one or more components into the nonthermal plasma generator; continuing the build of the nonthermal plasma generator.
16. The method of claim 15, wherein the one or more components are formed of a dielectric material
17. The method of claim 16, wherein a component of the one or more components is inserted in the separation between the electrodes in each pair of electrodes.
18. A nonthermal plasma generator built using the method of any one of the preceding claims.
19. A nonthermal plasma generator built as an integrated mass of material using an additive manufacture process, the nonthermal plasma generator comprising a plurality of electrodes arranged in at least one pair, wherein a separation between the electrodes in each pair of electrodes is controlled by the additive manufacture process.
20. An exhaust gas processing system comprising the nonthermal plasma generator of claim 18 or 19.
21 . A fuel cell system comprising the nonthermal plasma generator of claim 18 or 19.
22. A computer-readable data structure representing a design of a nonthermal plasma generator according to claim 18 or 19.
23. A computer-readable data structure representing machine instructions which, when performed by an additive manufacturing machine, cause the additive manufacture machine to perform the method of any one of claims 1 to 17.
24. A storage medium storing the data structure of at least one of claims 22 and 23.
PCT/GB2020/051963 2019-08-28 2020-08-17 Nonthermal plasma generator and method of manufacturing the same WO2021038194A1 (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1669563A1 (en) * 2003-09-11 2006-06-14 Hino Motors, Ltd. Exhaust gas-purifying device
US20170207523A1 (en) * 2015-09-28 2017-07-20 The Board Of Trustees Of The University Of Illinois Control of electromagnetic energy with spatially periodic microplasma devices
US20180333511A1 (en) * 2017-05-18 2018-11-22 The Board Of Trustees Of The University Of Illinois Microplasma devices for surface or object treatment and biofilm removal

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1669563A1 (en) * 2003-09-11 2006-06-14 Hino Motors, Ltd. Exhaust gas-purifying device
US20170207523A1 (en) * 2015-09-28 2017-07-20 The Board Of Trustees Of The University Of Illinois Control of electromagnetic energy with spatially periodic microplasma devices
US20180333511A1 (en) * 2017-05-18 2018-11-22 The Board Of Trustees Of The University Of Illinois Microplasma devices for surface or object treatment and biofilm removal

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PAULMIER T ET AL: "Use of non-thermal plasma for hydrocarbon reforming", CHEMICAL ENGENEERING JOURNAL, ELSEVIER, AMSTERDAM, NL, vol. 106, no. 1, 28 January 2005 (2005-01-28), pages 59 - 71, XP027702987, ISSN: 1385-8947, [retrieved on 20050128] *

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