Photocatalytic air treatment

Abstract

A photocatalytic reactor including a reaction chamber is provided. The reaction chamber includes a first set of fins, a second set of fins, a photocatalyst disposed on at least one face of each fin, and a light source arranged to illuminate at least a portion of the photocatalyst disposed on each fin. Each of the first set of fins is arranged such that a line extending from a base of the fin through a tip of the fin points to a first convergence point, and each of the second set of fins is arranged such that a line extending from a base of the fin through a tip of the fin points to a second convergence point. The first convergence point is different from the second convergence point, and both the first convergence point and the second convergence point are offset relative to a position of the light source.

Description

TECHNICAL FIELD

[0001] The present invention relates to a photocatalytic reactor for treating a gas stream, and to an air treatment device comprising a photocatalytic reactor. BACKGROUND

[0002] Air treatment devices treat air to remove pollutants. Conventional air treatment devices use only a particulate filter which physically traps airborne particles by size exclusion, a high efficiency particulate air (HEPA) filter removes at least 99.97% of 0.3 pm particles. Some air treatment devices use an activated carbon filter to filter volatile chemicals from the air. When used for air purification, activated carbon filters out pollutants by adsorption, and so has only a limited capacity, so the activated carbon filter eventually needs to be replaced if filtration performance is to be maintained. In addition to capturing pollutants, certain air pollutants can also be destroyed using technologies such as photocatalytic oxidation (PCO). Photocatalytic oxidation can be used to oxidise harmful air pollutants to less harmful compounds, for example to oxidise volatile organic compounds (VOCs) to carbon dioxide and water. The reaction is catalysed by a catalytic surface which is activated by the absorption of photons. Moisture and oxygen in the air provide the necessary hydrogen and oxygen atoms for the reaction to proceed, so no reactive chemicals are consumed in addition to the pollutants. SUMMARY

[0003] According to a first aspect of the present invention, there is provided a photocatalytic reactor comprising a reaction chamber arranged to receive a gas stream comprising one or more airborne pollutants. The reaction chamber comprises a first set of fins, a second set of fins, a photocatalyst for photocatalytic degradation of the one or more pollutants, the photocatalyst being provided on at least one face of each fin, and a light source arranged to irradiate at least a portion of the photocatalyst provided on each fin to facilitate photocatalytic degradation. Each of the first set of fins is arranged such that a line extending from a base of the fin through a tip of the fin points towards a first convergence point, and each of the second set of fins is arranged such that a line extending from a base of the fin through a tip of the fin points towards a second convergence point. The first convergence point is different from the second convergence point, and both the first convergence point and the second convergence point are offset relative to a position of the light source.

[0004] The first set of fins and the second set of fins can be arranged such that, for at least one face of each fin, light from the light source irradiates at least a portion of the length of the face along the entire height of the face. Each of the first set of fins and the second set of fins can have a straight and at least partially curved cross-section.

[0005] The first set of fins can extend inwardly from a first inner surface of the reaction chamber and the second set of fins extend inwardly from a second inner surface of the reaction chamber, the first and second inner surfaces generally facing the light source. The first and second inner surfaces can have different arc profiles, wherein the profile of the first inner surface is a mirror image of the profile of the second inner surface. The first and second inner surfaces can each have any one of a circular arc profile and a parabolic arc profile. The photocatalyst can be disposed on the first and second inner surfaces of the reaction chamber.

[0006] The light source can comprise a light emitting diode. The first and second inner surfaces can be arranged consecutively. The first and second inner surfaces can be arranged symmetrically about an optical axis of the light emitting diode. The first and second inner surfaces can be arranged such that at least a portion of the first inner surface is illuminated by a first half of the light emitting diode and at least a portion of the second inner surface is arranged to be illuminated by a second half of the light emitting diode. Each of the first and second sets of fins can be longitudinal, a longitudinal axis of each fin being perpendicular to the optical axis of the light emitting diode.

[0007] The light source can comprise a plurality of light emitting diodes, each arranged to illuminate at least a portion of the first and second sets of fins. The plurality of light emitting diodes can be distributed such that each light emitting diode illuminates a different portion of the length of at least one face of each fin. The plurality of light emitting diodes can be arranged longitudinally.

[0008] The reaction chamber can comprise an air inlet and an air outlet and be arranged such that an airflow passing between the air inlet and the air outlet contacts the photocatalyst. The first and second sets of fins can define a channel extending along the reaction chamber for the flow of air from the air inlet to the air outlet.

[0009] The reaction chamber can comprise at least one layer of transparent material dividing the reaction chamber into a first portion containing the photocatalyst and a second portion containing the light source. The first portion can be arranged to receive an airflow comprising one or more airborne pollutants.

[0010] The photocatalytic reactor can comprise a plurality of reaction chambers. The plurality of reaction chambers can be distributed about a common axis, each reaction chamber being arranged such that the first and second sets of fins extend inwardly and the light source is centrally disposed relative to the fins. The plurality of reaction chambers can be arranged consecutively. The plurality of reaction chambers can be arranged such that the arrangement has rotational symmetry about the common axis and preferably n-fold rotational symmetry, where n is equal to the number of reaction chambers.

[0011] According to a second aspect of the present invention, there is provided an air treatment apparatus comprising a photocatalytic reactor according to the first aspect. BRIEF DESCRIPTION OF DRAWINGS

[0012] The application will be described by way of example only with reference to the following drawings in which:

[0013] Figure 1A is a perspective view of an example of a photocatalytic reactor for an air treatment device;

[0014] Figure 1B is an end view of the photocatalytic reactor of Figure 1A

[0015] Figure 2A is a perspective view of another example of a photocatalytic reactor for an air treatment device;

[0016] Figure 2B is an end view of the photocatalytic reactor of Figure 2A

[0017] is a perspective view of another example of a photocatalytic reactor for an air treatment device; Figure 3A

[0018] Figure 3B is an end view of the photocatalytic reactor of Figure 3A

[0019] Figure 4 is an end view of yet another example of a photocatalytic reactor for an air treatment device;

[0020] Figure 5A is a perspective view of another example of a photocatalytic reactor for an air treatment device; and

[0021] Figure 5B is an end view of the photocatalytic reactor of Figure 5A DETAILED DESCRIPTION

[0022] Reference will now be made to Figure 1A and 1B ​​​​An example of an improved photocatalytic reactor is described by way of example only. The photocatalytic reactor is generally indicated by reference numeral 1000. The photocatalytic reactor 1000 comprises a reaction chamber 1001 arranged to receive a gas stream comprising one or more gas-borne pollutants and a photocatalyst 1004 for photocatalytic degradation of the one or more pollutants, the photocatalyst 1004 being provided on a substrate 1003 provided by the reaction chamber 1001. The photocatalytic reactor 1000 further comprises a light emitting diode printed circuit board ("LED PCB") 1012 comprising a printed circuit board 1008 to which a plurality of light emitting diodes 1009 are mounted to a first side 1006 of the printed circuit board 1008. The photocatalytic reactor 1000 is arranged such that the substrate 1003 is illuminated by the light emitting diodes 1009 to facilitate photocatalytic degradation. In particular, the substrate 1003 is arranged to shield the LED PCB 1012 such that light emitted from the light emitting diodes 1009 of the LED PCB 1012 is incident on the substrate 1003.

[0023] In Figure 1A and 1B In the example shown, the photocatalytic reactor 1000 comprises an elongate reaction chamber 1001 surrounding an elongate LED PCB 1012, the LED PCB 1012 extending along the length of the reaction chamber 1001. The reaction chamber 1001 comprises a reaction chamber inlet (not shown) at a first end of the reaction chamber 1001 and a reaction chamber outlet (not shown) at a second end of the reaction chamber 1001, such that a gas stream passing between the reaction chamber inlet and the reaction chamber outlet contacts the photocatalyst 1004 provided on the substrate 1003. A partition / barrier 1005A, 1005B then separates the photocatalyst 1004 reaction chamber from the LED PCB 1012, at least a portion of the partition 1005A, 1005B being transparent to radiation emitted by the light emitting diodes 1009 such that the photocatalyst 1004 can be illuminated by the light emitting diodes 1009. The plurality of light emitting diodes 1009 of the LED PCB 1012 are then spaced apart and aligned longitudinally along the first side 1006 of the length of the LED PCB 1012, thereby providing a light source along the entire length of the photocatalytic reactor 1000.

[0024] In Figure 1A and 1BIn the illustrated example, the substrate 1003 of the reaction chamber 1001 includes a plurality of protrusions provided by fins 1011A, 1011B, each protruding inwardly away from an interior surface of the reaction chamber 1001, with the photocatalyst 1004 disposed on at least one face of each fin 1011A, 1011B. These fins 1011A, 1011B provide a high surface area for photocatalytic degradation of pollutants. Each fin 1011A, 1011B is elongate, having a length (L) along the length of the elongate reaction chamber 1001, and a height (H) defined by how far the fin 1011A, 1011B protrudes inwardly away from the respective interior surface of the reaction chamber 1001. Thus, the fins 1011A, 1011B are longitudinal, with a longitudinal axis of each fin 1011A, 1011B perpendicular to the optical axis of the light emitting diode 1009. Thus, the fins 1011A, 1011B define a channel 1002 therebetween, extending along the length of the reaction chamber 1001, for air to flow from the air inlet to the air outlet. In the illustrated example, each fin 1011A, 1011B has a partially curved cross-section (i.e. fin profile) along its height. However, in alternative arrangements, each fin 1011A, 1011B can have a straight cross-section.

[0025] The fins 1011A, 1011B include a first set of fins 1011A and a second set of fins 1011B, with the photocatalyst 1004 disposed on each fin. The first set of fins 1011A and the second set of fins 1011B are arranged such that light from the light emitting diode 1009 illuminates at least a portion of the length of the face 1013 of each fin 1011A, 1011B along the entire height of the face 1013. In other words, each light emitting diode 1009 illuminates the entire height of at least one face 1013 of each fin 1011A, 1011B without being obscured by any adjacent fins, although multiple light emitting diodes 1009 can be required to illuminate the entire length of the fins 1011A, 1011B (e.g. multiple light emitting diodes distributed longitudinally). The light emitting diodes 1009 are distributed such that each illuminates a different, but possibly overlapping, portion of the length of at least one face 1013 of each fin 1011A, 1011B.

[0026] In Figure 1A and 1BIn the illustrated example, each of the first set of fins 1011A is arranged such that a line (e.g., extending along the height of the fin, similar to a string) extending from the base 1015 of the fin 1011A through the tip 1016 of the fin points to a first convergence point or intersection (Fl). Then, each of the second set of fins 1011B is arranged such that a line extending from the base 1015 of the fin 1011B through the tip 1016 of the fin 1011B points to a second convergence point (F2). The first convergence point (Fl) is different from the second convergence point (F2), and both the first convergence point (Fl) and the second convergence point (F2) are offset relative to the position of the light emitting diodes 1009.

[0027] The first set of fins 1011A extends inwardly from a first inner surface 1018A of the reaction chamber 1001, and the second set of fins 1011B extends inwardly from a second inner surface 1018B of the reaction chamber 1001, the first and second inner surfaces 1018A, 1018B generally facing the light emitting diodes 1009. The first and second inner surfaces 1018A, 1018B are arranged symmetrically about the optical axis (O) of the light emitting diodes, such that the first set of fins 1011A is arranged to be illuminated by a first half of each light emitting diode 1009, and the second set of fins 1011B is arranged to be illuminated by a second half of each light emitting diode 1009. In Figure 1A and 1B In the illustrated example, the photocatalyst 1004 is also disposed on the first and second inner surfaces 1018A, 1018B of the reaction chamber 1001.

[0028] The first and second inner surfaces 1018A, 1018B have different arcuate profiles (i.e., their cross-sections are arc segments having different foci), the profile of the first inner surface 1018A being a mirror image of the profile of the second inner surface 1018B. In other words, the first and second inner surfaces 1018A, 1018B are reflections of each other, such that together they have mirror / reflection symmetry. The first and second inner surfaces 1018A, 1018B can each have any one of a circular arc profile and a parabolic arc profile.

[0029] In Figure 1A and 1B In the illustrated example, the partitions 1005A, 1005B comprise two layers of transparent material disposed between and separating the light emitting diodes 1009 from the photocatalyst 1004. The two layers of transparent material comprise a first layer of transparent material 1005A separated from a second layer of transparent material 1005B by a gap. The layers of transparent material 1005A, 1005B are gas impermeable and transparent to the radiation emitted by the light emitting diodes 1009. In Figure 1A and 1BIn the example shown, the two layers of transparent material 1005A, 1005B are tubular and are arranged concentrically around the LED PCB 1012, the innermost of these tubes providing a conduit within which the LED PCB 1012 is located and which is arranged to allow airflow through the conduit in order to cool the light emitting diodes 1009.

[0030] Providing a double layer of the barrier between the light emitting diodes 1009 and the photocatalyst 1004 reduces heat loss between the first portion 1019 of the reaction chamber 1001 arranged to receive the airflow containing the pollutants and the second portion 1020 containing the LED PCB 1012, thereby improving energy efficiency. This reduction in heat loss is particularly beneficial when active cooling of the light emitting diodes 1009 is implemented.

[0031] Figure 2A and 2B Another example of an improved photocatalytic reactor is shown. The photocatalytic reactor is generally indicated by reference numeral 2000. The photocatalytic reactor 2000 comprises a reaction chamber 2001 arranged to receive an airflow containing one or more airborne pollutants and a photocatalyst 2004 for photocatalytic degradation of the one or more pollutants, the photocatalyst 1004 being provided on a substrate 2003 provided by the reaction chamber 1001. The photocatalytic reactor 2000 is very similar to the photocatalytic reactor described above with reference to Figure 1A and 1B and so like or corresponding parts or features of these embodiments are indicated by corresponding reference numerals. In particular, the photocatalytic reactor 2000 comprises an elongate reaction chamber 2001 around an elongate LED PCB 2012, the LED PCB 2012 extending along the length of the reaction chamber 2001. The reaction chamber 2001 comprises a reaction chamber inlet (not shown) at a first end of the reaction chamber 2001 and a reaction chamber outlet (not shown) at a second end of the reaction chamber 2001, such that an airflow passing between the reaction chamber inlet and the reaction chamber outlet contacts the photocatalyst 2004 provided on the substrate 2003. A barrier 2005 then separates the reaction chamber 2001 from the LED PCB 2012, at least a portion of the barrier 2005 being transparent to radiation emitted by the light emitting diodes 2009, 2010 such that the photocatalyst 2004 can be illuminated by the light emitting diodes 2009, 2010.

[0032] In Figure 2A and 2BIn the example shown, the LED PCB 2012 is double-sided. Therefore, the LED PCB 2012 includes a printed circuit board 2008, wherein a plurality of first light-emitting diodes 2009 are mounted to a first side 2006 of the printed circuit board, and a plurality of second light-emitting diodes 2010 are mounted to a second side 2007 of the printed circuit board. Thus, the LED PCB 2012 includes either a double-sided circuit board or a multilayer circuit board. The first light-emitting diodes 2009 of the LED PCB 2012 are spaced apart and longitudinally aligned along the first side 2006 of the length of the LED PCB 2012, and the second light-emitting diodes 2010 are spaced apart and longitudinally aligned along the second side 2007 of the length of the LED PCB 2012, thereby providing a light source along the entire length of the photocatalytic reactor 2000.

[0033] The photocatalytic reactor 2000 is thus arranged such that the substrate 2003 is irradiated by a first light-emitting diode 2009 and a second light-emitting diode 2010 to promote photocatalytic degradation. Specifically, the substrate 2003 is arranged to shield the LED PCB 2012 such that light emitted from the light-emitting diodes 2009 and 2010 of the LED PCB 2012 irradiates the substrate 2003. For this purpose, the substrate 2003 is arranged to surround the LED PCB 2012.

[0034] exist Figure 2A and 2B In the example shown, the reaction chamber 2001 of the photocatalytic reactor 2000 is also double-sided. Therefore, the reaction chamber 2001 includes a first side 2001A and a second side 2001B, wherein the first side 2001A is arranged to be illuminated by a first light-emitting diode 2009 disposed on a first side 2006 of a printed circuit board 2008, and the second side 2001B is arranged to be illuminated by a second light-emitting diode 2010 disposed on a second side 2007 of a printed circuit board 2008.

[0035] The dual-sided photocatalytic reactor configuration reduces the length of the reactor without compromising the overall volume, which is especially important when integrating photocatalytic reactors into home air treatment equipment, and also reduces material costs, particularly those associated with the partitions 2005A, 2005B and the printed circuit board 2008.

[0036] Then, the first side 2001A and the second side 2001B of the reaction chamber 2001 are replicated respectively. Figure 1A and 1BThe finned arrangement of the reaction chamber 1001 is shown. Specifically, the first side 2001A of the reaction chamber 2001 includes a first set of fins 2011A and a second set of fins 2011B, the second side 2001B of the reaction chamber 2001 includes a third set of fins 2011C and a fourth set of fins 2011D, and the photocatalyst 2004 is disposed on at least one face 2013 of each fin 2011. The first set of fins 2011A and the second set of fins 2001B are arranged such that light from the first light emitting diode 2009 illuminates at least a portion of the length of the face 2013 of each fin 2011A, 2011B along the entire height of the face 2013. The third set of fins 2011C and the fourth set of fins 2011D are then arranged such that light from the second light emitting diode 2010 illuminates at least a portion of the length of the face 2013 of each fin 2011C, 2011D along the entire height of the face 2013.

[0037] On the first side 2001A of the reaction chamber 2001, each of the first set of fins 2011A is arranged such that a line (e.g., extending along the height of the fin, similar to a string) extending from the base 2015 of the fin 2011A through the tip 2016 of the fin points to a first convergence point or intersection (Fl). Each of the second set of fins 2011B is then arranged such that a line extending from the base 2015 of the fin 2011B through the tip 2016 of the fin 2011B points to a second convergence point (F2). The first convergence point (Fl) is different from the second convergence point (F2), and both the first convergence point (Fl) and the second convergence point (F2) are offset relative to the position of the first light emitting diode 2009.

[0038] Correspondingly, on the second side 2001B of the reaction chamber 2001, each of the third set of fins 2011C is arranged such that a line extending from the base 2015 of the fin 2011C through the tip 2016 of the fin points to a third convergence point or intersection (F3). Each of the fourth set of fins 2011D is then arranged such that a line extending from the base 2015 of the fin 2011D through the tip 2016 of the fin 2011D points to a fourth convergence point (F4). The third convergence point (F3) is different from the fourth convergence point (F4), and both the third convergence point (F3) and the fourth convergence point (F4) are offset relative to the position of the second light emitting diode 2010.

[0039] A first set of fins 2011A extend inwardly from a first inner surface 2018A on a first side 2001A of the reaction chamber 2001, a second set of fins 2011B extend inwardly from a second inner surface 2018B on a first side 2001B of the reaction chamber 2001, the first and second inner surfaces 2018A, 2018B generally facing the first light emitting diode 2009. A third set of fins 2011C extend inwardly from a third inner surface 2018C on a second side 2001B of the reaction chamber 2001, a fourth set of fins 2011D extend inwardly from a fourth inner surface 2018D on a second side 2001B of the reaction chamber 2001, the third and fourth inner surfaces 2018C, 2018D generally facing the second light emitting diode 2010.

[0040] From Figure 2A And 2B It will be seen that the LED PCB 2012 is centrally located within the volume of the space defined by the substrate 2003. The partition 2005 thus comprises a single layer of transparent material disposed between and separating the light emitting diodes 2009, 2010 and the photocatalyst 2004. This layer of transparent material is gas impermeable and transparent to the radiation emitted by the light emitting diodes 2009, 2010. In Figure 2A And 2B In the example shown, the single layer of transparent material 2005 is tubular and arranged concentrically around the LED PCB 3012. This tube of transparent material 2005 provides a conduit within which the LED PCB 1012 is located and which is arranged to allow a flow of gas to pass through the conduit in order to cool the light emitting diodes 2009, 2010.

[0041] The skilled person will appreciate that it is possible to combine the key features of the photocatalytic reactors of Figure 1A , 1B 1A and 1B. Accordingly, a further example of an improved photocatalytic reactor will now be described with reference to Figure 3A And 3B The photocatalytic reactor is generally indicated by reference numeral 3000. The photocatalytic reactor 3000 comprises a reaction chamber 3001 arranged to receive a flow of gas containing one or more gas-borne pollutants and a photocatalyst 3004 for photocatalytic degradation of the one or more pollutants, the photocatalyst 1004 being provided on a substrate 3003 provided by the reaction chamber 1001. The photocatalytic reactor 3000 is very similar to the photocatalytic reactor described above with reference to Figure 2A And 2BThe photocatalytic reactor described, and therefore the corresponding reference numerals for similar or corresponding parts or features of these embodiments. In particular, the photocatalytic reactor 3000 comprises an elongate reaction chamber 3001 around an elongate LED PCB 3012, the LED PCB 2012 extending along the length of the reaction chamber 3001. The reaction chamber 3001 comprises a reaction chamber inlet (not shown) at a first end of the reaction chamber 3001 and a reaction chamber outlet (not shown) at a second end of the reaction chamber 3001, such that a gas stream passing between the reaction chamber inlet and the reaction chamber outlet contacts a photocatalyst 3004 provided on a substrate 3003. A partition / barrier 3005A, 3005B then separates the reaction chamber 3001 from the LED PCB 3012, at least a portion of the partition 3005A, 3005B being transparent to radiation emitted by the light emitting diodes 3009, 3010, such that the photocatalyst 3004 can be illuminated by the light emitting diodes 3009, 3010.

[0042] In Figure 3A and 3B the example shown, the LED PCB 3012 and the reaction chamber 3001 are both double-sided. However, unlike the example shown in Figure 2A and 2B the partition 3005A, 3005B separating the photocatalyst 304 from the LED PCB 3012 comprises two layers of transparent material. The two layers of transparent material comprise a first layer of transparent material 3005A separated from a second layer of transparent material 3005B by a gap. The layers of transparent material 3005A, 3005B are gas-impermeable and transparent to radiation emitted by the light emitting diodes 3009, 3010. In Figure 3A and 3B the example shown, the two layers of transparent material 3005A, 3005B are tubular and arranged concentrically around the LED PCB 3012, the innermost of the tubes providing a conduit within which the LED PCB 3012 is located and which is arranged to allow a gas stream to pass through it in order to cool the light emitting diodes 3009, 3010.

[0043] Another example of an improved photocatalytic reactor will now be described with reference to Figure 4 The photocatalytic reactor is generally indicated by reference numeral 4000 and is shown in Figure 4photocatalytic reactor 4000 includes three reaction chambers 4001, 4101, 4201 and a photocatalyst 4004, each reaction chamber arranged to receive a gas stream containing one or more gas-borne pollutants, the photocatalyst 4004 for photocatalytic degradation of the one or more pollutants, the photocatalyst 4004 disposed on a substrate 4003 provided by each reaction chamber 4001, 4101, 4201. The photocatalytic reactor 4000 further includes a light emitting diode printed circuit board (“LED PCB”) 4012, 4112, 4212 within each reaction chamber 4012, 4112, 4212. Each LED PCB 4012, 4112, 4212 includes a printed circuit board 4008, a plurality of light emitting diodes 4009 mounted to a first side of the printed circuit board 4008. The photocatalytic reactor 4000 is arranged such that the substrate 4003 provided by each reaction chamber 4001, 4101, 4201 is illuminated by the light emitting diodes 4009 of the corresponding LED PCB 4012, 4112, 4212 to facilitate photocatalytic degradation. In particular, the substrate 4003 provided by each reaction chamber 4012, 4112, 4212 is arranged to shield the corresponding LED PCB 4012, 4112, 4212 such that light emitted from the light emitting diodes 4009 of the LED PCB 4012, 4112, 4212 is incident on the substrate 4003.

[0044] In Figure 4 In the example shown, each reaction chamber 4001, 4101, 4201 is elongate and surrounds a corresponding elongate LED PCB 4012, 4112, 4212 extending along a length of the reaction chamber 4001, 4101, 4201. Each reaction chamber 4001, 4101, 4201 includes a reaction chamber inlet (not shown) at a first end of the reaction chamber and a reaction chamber outlet (not shown) at a second end of the reaction chamber, such that a gas stream passing between the reaction chamber inlet and the reaction chamber outlet contacts the photocatalyst 4004 disposed on the substrate 4003. A partition / barrier 4005 then separates the photocatalyst 4004 from each LED PCB 4012, 4112, 4212, at least a portion of the partition 4005 being transparent to radiation emitted by the light emitting diodes 4009 such that the photocatalyst 4004 can be illuminated by the light emitting diodes 4009. The plurality of light emitting diodes 4009 of each LED PCB 4012, 4112, 4212 are then spaced apart and longitudinally aligned along the first side of the length of the printed circuit board 4008, thereby providing a light source along the entire length of the corresponding reaction chamber 4001, 4101, 4201.

[0045] In Figure 4In the illustrated example, the substrate 4003 of each reaction chamber 4001, 4101, 4201 includes a plurality of protrusions provided by fins 4011A, 4011B, each protruding inwardly away from an interior surface of the reaction chamber 4001A, 4001B, 4001C, with a photocatalyst 4004 disposed on at least one face of each fin 4011A, 4011B. These fins 4011A, 4011B provide a high surface area for photocatalytic degradation of pollutants. Each fin 4011A, 4011B is elongate, having a length along the length of the elongate reaction chamber 4001A, 4001B, 4001C, and a height defined by how far the fin 4011A, 4011B protrudes inwardly away from the respective interior surface of the reaction chamber 4001, 4101, 4201. Thus, the fins 4011A, 4011B are longitudinal, with a longitudinal axis of each fin 4011A, 4011B perpendicular to the optical axis of the light emitting diode 4009. The fins 4011A, 4011B thus define a channel 4002 therebetween, extending along the length of the respective reaction chamber 4001, 4101, 4201, for the flow of air from the air inlet to the air outlet. In the illustrated example, each fin 4011A, 4011B has a straight cross-section (i.e. fin profile) along its height. However, in alternative arrangements, each fin 4011A, 4011B can have a curved cross-section.

[0046] The fins 4011A, 4011B within each reaction chamber 4001, 4101, 4201 include a first set of fins 4011A and a second set of fins 4011B, with a photocatalyst 1004 disposed on each fin. The first set of fins 4011A and the second set of fins 4011B are arranged such that light from the corresponding light emitting diode 4009 illuminates at least a portion of the length of the face 4013 of each fin 4011A, 4011B along the entire height of the face 4013. In other words, within the reaction chamber 4001, 4101, 4201, each light emitting diode 4009 illuminates the entire height of at least one face 4013 of each fin 4011A, 4011B without being obscured by any adjacent fins, although multiple light emitting diodes 4009 can be required to illuminate the entire length of the fin 4011A, 4011B (e.g. multiple light emitting diodes distributed longitudinally). Within each reaction chamber 4001, 4101, 4201, the light emitting diodes 4009 are distributed to each illuminate a different, but possibly overlapping, portion of the length of at least one face 4013 of each fin 4011A, 4011B.

[0047] In Figure 4In the illustrated example, within each reaction chamber 4001, 4101, 4201, each of the first set of fins 4011A is arranged such that a line (e.g., extending along the height of the fin, similar to a chord line) extending from the base 4015 of the fin 4011A through the tip 4016 of the fin points to a first convergence point or intersection (Fl). Then, each of the second set of fins 4011B is arranged such that a line extending from the base 4015 of the fin 4011B through the tip 4016 of the fin 4011B points to a second convergence point (F2). The first convergence point (Fl) is different from the second convergence point (F2), and both the first convergence point (Fl) and the second convergence point (F2) are offset relative to the position of the light emitting diode 4009.

[0048] The first set of fins 4011A extend inwardly from a first inner surface 4018A of the respective reaction chamber 4001, 4101, 4201, and the second set of fins 4011B extend inwardly from a second inner surface 4018B of the respective reaction chamber 4001, 4101, 4201, the first inner surface 4018A and the second inner surface 4018B generally facing the light emitting diode 4009. The first inner surface 4018A and the second inner surface 4018B are arranged symmetrically about the optical axis of the light emitting diode such that the first set of fins 4011A is arranged to be illuminated by a first half of each light emitting diode 4009, and the second set of fins 4011B is arranged to be illuminated by a second half of each light emitting diode 4009. In the illustrated example, the first inner surface 4018A and the second inner surface 4018B are arranged to be illuminated by a first half of each light emitting diode 4009, and the first set of fins 4011A is arranged to be illuminated by a second half of each light emitting diode 4009. Figure 4 In the illustrated example, the photocatalyst 4004 is also provided on the first inner surface 4018A and the second inner surface 4018B of each reaction chamber 4001, 4101, 4201.

[0049] Within each reaction chamber 4001, 4101, 4201, the first inner surface 4018A and the second inner surface 4018B have different arc-shaped profiles (i.e., their cross-sections are arc segments having different foci), the profile of the first inner surface 4018A being a mirror image of the profile of the second inner surface 4018B. In other words, the first inner surface 4018A and the second inner surface 4018B are reflections of each other such that they together have mirror / reflection symmetry. The first inner surface 4018A and the second inner surface 4018B can each have any one of a circular arc profile and a parabolic arc profile.

[0050] From Figure 4It will be seen that the reaction chambers 4001, 4101, 4201 are distributed around a common axis. In particular, the three reaction chambers 4001, 4101, 4201 are arranged so that the arrangement has three-fold rotational symmetry around the common axis. The three reaction chambers 4001, 4101, 4201 are also arranged consecutively so that the substrates 4003 of the reaction chambers 4001, 4101, 4201 define the volume of the space in which the LED PCBs 4012, 4112, 4212 are located. The partition 4005 thus comprises a single layer of transparent material disposed between and separating the LED PCBs 4012, 4112, 4212 and the photocatalyst 4004. The layer of transparent material is gas impermeable and transparent to the radiation emitted by the light emitting diodes 4009. In Figure 4 In the example shown, the single layer of transparent material 4005 has the form of a lobed tube and is arranged concentrically around the LED PCBs 4012, 4112, 4212. The lobed tube 4005 of transparent material provides a conduit within which the LED PCBs 4012, 4112, 4212 are located and which is arranged to allow a flow of gas through the conduit in order to cool the light emitting diodes 4009.

[0051] The photocatalytic reactor 4000 described above comprises three reaction chambers. The skilled person will appreciate that the photocatalytic reactor 4000 can comprise any number of reaction chambers. The photocatalytic reactor 4000 described above is elongate. The skilled person will appreciate that this need not be the case.

[0052] Figure 1A 、 1B The photocatalytic reactors of 2A, 2B, 3A, 3B and 4 all comprise fins which are arranged to maximise the surface area which is illuminated, thereby maximising the efficiency of the photocatalytic reactor. In doing so, this arrangement also minimises the number of light emitting diodes required to illuminate the fins, as there is no shadowing optimising the surface area illuminated by each light emitting diode.

[0053] Figure 1A 、 1B The photocatalytic reactors of 2A, 2B, 3A, 3B and 4 all comprise fins which provide a relatively high surface area of photocatalyst. An example of an alternative improved photocatalytic reactor which does not comprise such fins will now be described with reference to Figure 5A and 5B The photocatalytic reactor generally indicated by reference numeral 5000. The photocatalytic reactor 5000 comprises two reaction chambers 5001, 5101 and a photocatalyst 5004, each reaction chamber being arranged to receive a flow of gas comprising one or more gas-borne pollutants, the photocatalyst 5004 being for photocatalytic degradation of the one or more pollutants, the photocatalyst 5004 being disposed on a substrate 5003, 5103 provided by each reaction chamber 5001, 5101.Figure 5A and 5B In the example shown, the photocatalytic reactor 5000 also includes a double-sided light-emitting diode printed circuit board (“LED PCB”) 5012. Therefore, the LED PCB 5012 includes a printed circuit board 5008, a plurality of first light-emitting diodes 5009 mounted to a first side 5006 of the printed circuit board 5008, and a plurality of second light-emitting diodes 5010 mounted to a second side 5007 of the printed circuit board 5008. Thus, the LED PCB 5012 includes either a double-sided circuit board or a multilayer circuit board.

[0054] The photocatalytic reactor 5000 is thus arranged such that the substrate 5003 of the first reaction chamber 5001 is illuminated by a first light-emitting diode 5009 mounted on a first side 5006 of a printed circuit board 5008, while the substrate 5103 of the second reaction chamber 5101 is illuminated by a second light-emitting diode 5010 mounted on a second side 5007 of the printed circuit board 5008. Specifically, the substrate 5003 of the first reaction chamber 5001 is arranged to shield the LED PCB 5012, such that light emitted from the first light-emitting diode 5009 illuminates the substrate 5003, and the substrate 5103 of the second reaction chamber 5101 is arranged to shield the LED PCB 5012, such that light emitted from the second light-emitting diode 5010 illuminates the substrate 5103.

[0055] exist Figure 5A and 5B In the example shown, the photocatalytic reactor 5000 is elongated, and the first and second reaction chambers 5001 and 5101 are distributed around the axis of the photocatalytic reactor 5000, such that the arrangement has double rotational symmetry about the axis. The reaction chambers 5001 and 5101 are also arranged continuously, such that the substrates 5003 and 5103 of the reaction chambers 5001 and 5101 define the volume of the space in which the LED PCB 5012 is located. In particular, the LED PCB 5012 is elongated, axially aligned within the elongated photocatalytic reactor 5000, and extends along the length of the reaction chambers 5001 and 5101. The first light-emitting diodes 5009 of the LED PCB 5012 are spaced apart and longitudinally aligned along a first side 5006 of the length of the LED PCB 5012, and the second light-emitting diodes 5010 are spaced apart and longitudinally aligned along a second side 5007 of the length of the LED PCB 5012, thereby providing a light source along the entire length of the photocatalytic reactor 5000.

[0056] Reaction chambers 5001 and 5101 each include a reaction chamber inlet (not shown) at a first end of the reaction chambers 5001 and 5101 and a reaction chamber outlet (not shown) at a second end of the reaction chambers 5001 and 5101, such that airflow passing between the reaction chamber inlet and the reaction chamber outlet contacts the photocatalyst 5004 disposed on the respective substrates 5003 and 5103. A partition / barrier 5005 then separates the reaction chambers 5001 and 5101 from the LED PCB 5012. At least a portion of the partition 5005 is transparent to radiation emitted by the light-emitting diodes 5009 and 5010, allowing the photocatalyst 5004 to be irradiated by the light-emitting diodes 5009 and 5010. Figure 5A and 5B In the example shown, the partition 5005 comprises a single layer of transparent material that is tubular and concentrically arranged around the LED PCB 5012. This transparent material tube provides a conduit within which the LED PCB 5012 is located, and the conduit is arranged to allow airflow through it to cool the light-emitting diodes 5009 and 5010.

[0057] exist Figure 5A and 5B In the example shown, each reaction chamber 5001, 5101 includes a first inner surface 5018A, 5118A and a second inner surface 5018B, 5118B, on which a photocatalyst 5004 is disposed. The first inner surface 5018A, 5118A and the second inner surface 5018B, 5118B have different parabolic arc profiles, meaning their cross-sections are curve segments with different focal points, and the profiles of the first inner surface 5018A, 5118A are mirror images of the profiles of the second inner surface 5018B, 5118B. The photocatalytic reactor 5000 is thus arranged such that the light-emitting diodes 5009, 5010 of the corresponding sides 5006, 5007 of the LED PCB 5012 illuminate the first inner surface 5018A, 5118A and the second inner surface 5018B, 5118B. Specifically, the first inner surfaces 5018A, 5118A and the second inner surfaces 5018B, 5118B of each reaction chamber 5001, 5101 are arranged symmetrically around the optical axis (O) of the corresponding light-emitting diodes 5009, 5010, such that the first inner surfaces 5018A, 5118A are illuminated by the first half of the light-emitting diodes 5009, 5010, and the second inner surfaces 5018B, 5118B are arranged to be illuminated by the second half of the light-emitting diodes 5009, 5010. The first inner surfaces 5018A, 5118A and the second inner surfaces 5018B, 5118B of each reaction chamber 5001, 5101 are also continuous.

[0058] existFigure 5A and 5B In this arrangement, the lack of surface features (such as fins or other protrusions) makes it possible, despite being related to Figure 1A , 1B Compared to the arrangements shown in 2A, 2B, 3A, 3B, and 4, the total surface area of ​​the photocatalyst 5004 is reduced. However, the substrates 5003 and 5103 supporting the photocatalyst 5004 are positioned as close as possible to the light sources 5009 and 5010 to maximize the irradiance of the photocatalyst 5004. However, a gap is required between the partition 5005 and the substrates 5003 and 5103 to allow air to pass through the photocatalytic reactor 5000, and optimizing the spacing between the partition 5005 and the substrates 5003 and 5103 provides a thinner air layer, which optimizes the cleanliness and mixing of air within the reaction chambers 5001 and 5101. Figure 5A and 5B In the example shown, the diameter (D) of the partition 5005 is approximately 35 mm, and the maximum distance (S) between the outer surface of the partition 5005 and the substrates 5003 and 5013 is approximately 3 mm. However, this distance may not exceed 10 mm, preferably not more than 7 mm, and more preferably from 1 mm to 7 mm.

[0059] It is also desirable to produce uniform irradiance across the entire catalytic surface, ensuring that the air within the photocatalytic reactor is treated uniformly. However, LEDs do not emit light in a cylindrically symmetrical manner, but rather in a Lambertian distribution. Conventional photocatalytic reactors utilizing LED light sources typically have cylindrical substrates, thus requiring lenses between the LEDs and the substrate to uniformly distribute the light emitted by the LEDs across the substrate surface. Including the lenses increases the cost and size of the LED packaging. To overcome this problem, the applicant has discovered that a more uniform irradiance can be achieved by providing a substrate whose cross-sectional shape is defined by two distinct parabolic arcs. In particular, the use of this parabolic profile facilitates the shaping of the inner surface supporting the catalyst to account for the localized irradiance provided by the LED light source. This inner surface with a parabolic profile reduces the irradiance difference at the inner surface as a function of angle α, thereby providing greater irradiance uniformity at the inner surface containing the photocatalyst. In this respect, the cross-sectional profile shape of each of the first inner surfaces 5018A, 5118A and the second inner surfaces 5018B, 5118B can be defined by a Bézier curve, specifically a quadratic Bézier curve. Therefore, the cross-sectional profile of each of the first inner surfaces 5018A, 5118A and the second inner surfaces 5018B, 5118B can be defined by a three-point Bézier curve, which is defined by the following formula:

[0060] B(t)=(1-t) 2 p0+2(1-t)tp1+t2 P2,t e [0,1]

[0061] where P0is the start point of the curve, P2is the end point of the curve, and P1is the control point of the curve. Using a Bezier curve, a more uniform irradiance can be provided over the photocatalyst surface as a function of the angle a.

[0062] As previously mentioned, the skilled person will appreciate that the above-described photocatalytic reactor can be used to replace a conventional photocatalytic reactor in an air treatment device.

[0063] In the foregoing description, reference has been made to overall or individual features which have known, obvious or foreseeable equivalents; such equivalents are covered by the scope of the invention as described and claimed. The reader will understand that the specification is illustrative in nature and that modifications or changes in detail can be effected without departing from the true scope of the application. The true scope of the application is to be determined by reference to the claims, which should be construed in the light most favorable to the applicant. The reader will also understand that the features of the application described in the specification can be used in any combination or sub-combination, and are not limited to the combinations and sub-combinations explicitly described.

Claims

1. A photocatalytic reactor, comprising: A reaction chamber, arranged to receive an airflow containing one or more airborne pollutants, the reaction chamber comprising: A first set of fins, a second set of fins, a photocatalyst for photocatalytic degradation of one or more pollutants disposed on at least one surface of each fin, and a light source arranged to irradiate at least a portion of the photocatalyst disposed on each fin to promote photocatalytic degradation. Each of the first set of fins is arranged such that a line extending from the base of the fin through the tip of the fin points to a first convergence point. In this arrangement, each of the second set of fins is positioned such that a line extending from the base of the fin through its tip points towards a second convergence point; and The first convergence point is different from the second convergence point, and both the first and second convergence points are offset relative to the position of the light source. The first set of fins extends inward from the first inner surface of the reaction chamber, and the second set of fins extends inward from the second inner surface of the reaction chamber. Both the first and second inner surfaces typically face the light source. The first inner surface and the second inner surface are arranged symmetrically around the optical axis of the light source, such that the first set of fins is arranged to be illuminated by the first half of the light source, and the second set of fins is arranged to be illuminated by the second half of the light source.

2. The photocatalytic reactor according to claim 1, wherein, The first set of fins and the second set of fins are arranged such that for at least one face of each fin, light from the light source illuminates at least a portion of the length of the face along the entire height of the face.

3. The photocatalytic reactor according to claim 1, wherein, Each of the first set of fins and the second set of fins has either a straight or at least partially curved cross-section.

4. The photocatalytic reactor according to claim 1, wherein, The first inner surface and the second inner surface have different arcuate profiles, and the profile of the first inner surface is a mirror image of the profile of the second inner surface.

5. The photocatalytic reactor according to claim 4, wherein, The first inner surface and the second inner surface each have either a circular arc profile or a parabolic arc profile.

6. The photocatalytic reactor according to any one of claims 1 to 5, wherein, The photocatalyst is disposed on the first inner surface and the second inner surface of the reaction chamber.

7. The photocatalytic reactor according to any one of claims 1 to 5, wherein, The light source includes a light-emitting diode.

8. The photocatalytic reactor according to claim 7, wherein, The first inner surface and the second inner surface are arranged symmetrically around the optical axis of the light-emitting diode.

9. The photocatalytic reactor according to claim 8, wherein, Each fin is longitudinal, and the longitudinal axis of each fin is perpendicular to the optical axis of the light-emitting diode.

10. The photocatalytic reactor according to any one of claims 1 to 5, wherein, The light source includes a plurality of light-emitting diodes, each of which is arranged to illuminate at least a portion of the first set of fins and the second set of fins.

11. The photocatalytic reactor according to claim 10, wherein, The plurality of light-emitting diodes are distributed such that each light-emitting diode illuminates a different portion of the length of at least one face of each fin.

12. The photocatalytic reactor according to any one of claims 11, wherein, The multiple light-emitting diodes are aligned vertically.

13. The photocatalytic reactor according to any one of claims 1 to 5, wherein, The reaction chamber includes an air inlet and an air outlet, and is arranged such that an airflow passing between the air inlet and the air outlet contacts the photocatalyst.

14. The photocatalytic reactor according to claim 13, wherein, The first set of fins and the second set of fins define a channel extending along the reaction chamber for the flow of air from the air inlet to the air outlet.

15. The photocatalytic reactor according to any one of claims 1 to 5, wherein, The reaction chamber includes at least one layer of transparent material that separates the photocatalyst from the light source.

16. The photocatalytic reactor according to any one of claims 1 to 5, wherein, The photocatalytic reactor comprises multiple reaction chambers.

17. The photocatalytic reactor according to claim 16, wherein, The plurality of reaction chambers are distributed around a common axis, each reaction chamber is arranged such that the first set of fins and the second set of fins extend inward, and the light source is centered relative to the fins.

18. The photocatalytic reactor according to claim 17, wherein, The multiple reaction chambers are arranged in a continuous sequence.

19. The photocatalytic reactor according to claim 18, wherein, The plurality of reaction chambers are arranged such that the arrangement is rotationally symmetric about the common axis.

20. The photocatalytic reactor according to claim 19, wherein, The plurality of reaction chambers are arranged such that the arrangement has n-fold rotational symmetry about the common axis, where n is equal to the number of reaction chambers.

21. An air treatment apparatus comprising a photocatalytic reactor according to any one of claims 1 to 20.

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