GB2611865A

GB2611865A - An air treatment device

Info

Publication number: GB2611865A
Application number: GB2212156.0A
Authority: GB
Inventors: Dominik Moczek Aleksander
Original assignee: Equipmake Ltd
Current assignee: Equipmake Ltd
Priority date: 2021-08-23
Filing date: 2022-08-22
Publication date: 2023-04-19
Also published as: GB202112057D0; WO2023026031A1; GB202212156D0

Abstract

An air treatment device 10 comprising an air inlet 14, an air outlet 16 and a conduit 12 defining a flow path between the two. The conduit comprises a negative electrode 18 upstream of a positive electrode 20, both being connected to a voltage supply to generate an electrostatic field to disinfect the air flow. A negative voltage of 5kV is generated at the anode to produce ozone and a positive voltage of 5kV at the cathode to decompose the ozone flowing past the positive electrode. The cathode may have a greater surface area than the anode and be longer in the direction of flow to reduce the amount of ozone emitted by the device. There may be an elongate UV light (42, figure 4) source located either upstream of the anode or downstream of the cathode and the conduit may include a reflector (44, figure 4) to reflect the UV light towards the interior of the duct. The UV source could also be located in a chamber (52, figure 5) along the conduit. An air treatment device (40, figure 4) including a UV light source is also claimed.

Description

Title: An air treatment device

Field of the disclosure

The present disclosure relates to an air treatment device and more particularly to such a device which is suitable for installation in a vehicle

Background to the disclosure

io There is increasing awareness of the need to treat air supplied to enclosed spaces within vehicles or buildings following the Covid-I_ 9 pandemic. It may be desirable to treat air drawn from the ambient atmosphere, and there is a greater demand to be able to treat air which is recirculated within a vehicle or building. Recirculation allows warmed or cooled air to be retained and thereby reduce the amount of energy consumed in controlling the internal temperature However, there is a risk that recirculated air may carry bacteria or viruses exhaled by passengers or building users.

Summary of the disclosure

The present disclosure provides an air treatment device comprising: an air inlet; an air outlet; a conduit defining an air flow path between the air inlet and the air outlet, a negative electrode in the conduit, a positive electrode in the conduit and downstream of the negative electrode, and a voltage supply coupled to the negative and positive electrodes and configured to generate a negative voltage with a magnitude of at least 5kV at the negative electrode and a positive voltage with a magnitude of at least 5kV at the $0 positive electrode to decompose molecules of ozone in air flowing along the conduit past the positive electrode.

This configuration has been found to form an electrostatic field which provides an effective and reliable means by which to eradicate bacteria and/or virus particles carried by a flow of air.

The power consumption of the device may be relatively low compared to other means of purifying air. For example, 60W may be sufficient to power a device able to treat air flowing at a rate high enough to supply a typical bus in relatively low humidity, increasing to around 180W in high humidity conditions. It may be necessary to supply at least around 10 litres/min per passenger (and possibly as much as 1000 io litres/s in total), and a device according to the present disclosure may be arranged to handle a sufficient flow rate for such a vehicle with relatively low power consumption.

It has been determined that an electrode held at a voltage with a magnitude of at least 51KV is effective to kill bacteria and viruses in an air flow passing over the surface of the electrode.

It is preferable for the voltages of the negative and positive electrodes to be of substantially equal and opposite values, that is at an equal magnitude of potential difference relative to OV.

Preferably, the electrodes are held at respective negative and positive voltages having a magnitude in a range from 5kV to 100kV.

The voltage supply may be configured to generate a negative voltage with a magnitude of at least 10kV at the negative electrode and a positive voltage with a magnitude of at least 10kV at the positive electrode.

In further examples, the voltage supply may be configured to generate a negative $0 voltage with a magnitude of at least 25kV at the negative electrode and a positive voltage with a magnitude of at least 25kV at the positive electrode. Voltages of this magnitude may be preferable in implementations for use in passenger vehicles such as buses.

The voltage supply is preferably a linear DC power supply. Each of the positive and negative electrodes may be coupled to a common voltage supply or alternatively the voltage supply may comprise a separate voltage supply device for each electrode (with the separate supplies connected to a common ground).

The high voltage negative electrode may break down the bonds of oxygen molecules in the air to create free radicals of oxygen which then combine with oxygen molecules to form ozone The ozone may act to oxidise and destroy bacteria and other io contaminants in the gas flow.

Ozone is however a toxic gas in large doses and the second, positive electrode acts to decompose ozone so that it is converted to oxygen molecules. In addition, the second electrode forms a high electric field gradient within the conduit which acts to kill bacteria and viruses remaining in the air flow.

Preferably, the positive electrode has a larger surface area than the negative electrode and/or the positive electrode is longer than the negative electrode, with the length of each electrode measured in the direction of the air flow path past the electrode. This significantly reduces the amount of ozone outputted by the device, in comparison to a device using positive and negative electrodes with equal surface areas and/or dimensions. In some preferred examples, the surface area of the positive electrode is at least two or around two to five times greater than that of the negative electrode. In some cases, the positive electrode may be at least two or around two to five times longer than the negative electrode in the direction of air flow. The length of time that a molecule is in close proximity to an electrode is dependent on its physical length in the direction of air flow. A longer electrode therefore increases the likelihood of a molecule of ozone being decomposed by the electric field adjacent to the electrode.

3o Each of the negative and positive electrodes may comprise a mesh formed of conductive material, such as a metal for example.

In other implementations, each of the negative and positive electrodes comprises a rolled sheet of conductive material, with some and preferably all adjacent layers of the material spaced apart The layers may be spaced apart by spacers. The spacers may be elongate and extend substantially parallel to the longitudinal axis about which the sheet is rolled. Each electrode may be located in the conduit such that its longitudinal axis is substantially parallel to the direction of air flow along the conduit The conductive material may be a metal such as aluminium, for example.

The present disclosure further provides an air treatment device comprising an air inlet, io an air outlet, a conduit defining an air flow path between the air inlet and the air outlet, and a UV light source in the conduit for irradiating air flowing through the conduit with UV light.

The device may include a UV light source upstream of the negative electrode or downstream of the positive electrode. The UV light source may be located in the conduit containing the electrodes for example. Exposure of the air flow to UV light may act to reduce (or reduce further) the amount of ozone, bacteria and/or virus particles in the air flow emitted by the device. Preferably, the light source is arranged to emit UV light having a wavelength in the range 200nm to 280nm, and preferably the UV light source is configured to emit UV light in the range 240 to 280 nm. The UV light emitted by the source may be restricted to be within the range 240 to 280nm to decompose ozone and kill bacteria and virus particles in the air flow. Inclusion of wavelengths below 240nm may increase the amount of ozone.

In some implementations, a reflector may be carried by the conduit (or an inwardly facing surface of the conduit may be reflective) for reflecting UV light from the light source back towards the interior of the conduit. This may increase the amount of ozone decomposed by UV radiation within the conduit 3o Preferably, the conduit is tubular and the UV light source is elongate. The conduit may be formed from a single component or may be an assembly of multiple elements. The UV light source may extend longitudinally along the conduit. The UV light source may be spaced from the walls of the conduit. The reflector (or the walls themselves) may provide a curved reflecting surface.

The UV light source may comprise a single UV light source or a plurality of such sources. If a plurality of UV light sources are included, it is preferable to power them using a common power supply so that the light is emitted in phase from the sources.

In further examples, the conduit includes a chamber, the chamber surrounds a plurality of elongate UV light sources having respective longitudinal axes, the io chamber has a chamber inlet and a chamber outlet, an air flow path is defined between the chamber inlet and the chamber outlet, and the longitudinal axes of the UV light sources are orientated transversely with respect to portions of the air flow path from the chamber inlet to the chamber outlet.

Preferably, the chamber includes at least one baffle which extends partway across the chamber in a transverse direction with respect to the longitudinal axes of the UV light sources.

Inwardly facing surfaces of the chamber may be designed to reflect UV light back towards the interior of the chamber. The housing may be formed of a material having suitable reflective properties, such as aluminium for example. Alternatively, a reflective coating may be applied to inwardly facing surfaces of the housing or a reflector may be mounted within the housing.

The present disclosure also provides a vehicle including a device as disclosed herein for treating air flowing to an interior passenger space of the vehicle.

Brief description of the drawings

$0 Examples of the present disclosure will now be described with reference to the accompanying schematic drawings, wherein: Figure 1 shows a cross-sectional side view of an air treatment device according to an example of the present disclosure; Figure 2 shows a perspective view of an electrode configuration suitable for use in examples of the present disclosure; Figure 3 is a circuit diagram of a power supply for a device according to an example of the present disclosure; and Figures 4 and S show cross-sectional side views of UV light sources for use in a device according to an example of the present disclosure.

io Detailed description

Figure 1 is a cross-sectional view of a high voltage air treatment device 10 according to one implementation of the present disclosure. It includes an air conduit 12 having an inlet 14 at one end and an outlet 16 at its opposite end. First and second electrodes 18, 20 respectively are located within the conduit. The first electrode 18 is closer to the air inlet 14 than the second electrode 20. Thus, air flowing through the conduit from its inlet 14 first passes over the surface of the first electrode 18 and then subsequently flows over the surface of the second electrode 20.

The conduit may have a diameter of around 100mm. The first and second electrodes 18, 20 may be spaced apart along the direction of gas flow within the conduit by a distance L of around 50 to 750mm, for example A passive electrostatic field is formed between the electrodes.

The region of the conduit including the two electrodes is surrounded by an electrically insulating component 22. This component may also extend longitudinally beyond the electrodes As the electrodes are at a high voltage during use of the device, the insulating component serves to electrically isolate the electrodes from their surroundings. The insulating component 22 may comprise at least two layers of $0 insulating material. The component may be in the form of a plastic tube with an outer coating of sprayed polyurethane or urethane.

The first electrode may operate at a negative voltage of down to around -25kV, with the second electrode operating at a positive voltage of a similar magnitude, that is up to around +25kV, for example The positive electrode may have a larger surface area than the negative electrode. For example, in one implementation, the negative electrode is 200mm long in a direction parallel to the length of the conduit and the positive electrode is 400mm long in that direction. These electrodes may be spaced apart along the conduit by a distance of around 55 to 250mm for example. This distance may be selected having regard to the io air flow speed along the conduit.

Each electrode may extend across the whole internal cross-section of the conduit.

Each electrode may be formed from a mesh of conductive material with silver plating is on its outer surface In other examples, each electrode may in the form of a rolled sheet of conductive material, with adjacent layers of the material spaced apart by spacers. One such implementation is depicted in Figure 2. It consists of a roll of aluminium foil 24 which is rolled around a longitudinal axis 28. Successive layers of the roll are spaced apart by spacers 26. In use, the electrode is orientated such that the air flow travels parallel to the longitudinal axis of the roll.

An end portion of the roll shown in Figure 2 is unfurled to expose some of the spacers for the purposes of illustration. The spacers are thin, straight lengths of material which extend across the width of the sheet of conductive material, from one edge to the other. They may be formed of insulating or conductive material. They may separate adjacent layers of the roll by a distance of around 0.5 to 2mm. The spacers may be equally spaced apart along the length of the sheet. They serve to separate the 3o adjacent layers of the roll and thereby increase the surface area of the sheet that is exposed to the air flowing past the electrode.

Figure 3 shows a circuit diagram of a power supply 30 for a device according to an example of the present disclosure in which the first and second electrodes are held at potentials of -25kV and +25kV, respectively. The power supply includes an oscillator for outputting a 22V alternating current at a frequency of at least 2501d-1z and able to provide around 50W (for an air flow of 280 litres per second, with higher air flows requiring a higher power output). The output of the oscillator is coupled to two networks 34 and 36 of capacitors and diodes, each of which forms a voltage multiplier for generating a DC voltage for a respective electrode of the device. Network 34 generates a positive voltage on its output 38 and network 36 generates a negative io voltage on its output 40. In the example illustrated, each capacitor has a capacitance of lOnF and diodes of type 2CL25 are used.

It will be appreciated that other voltage multiplier configurations may be used Figure 4 shows a further assembly 40 that may be included in a device according to the present disclosure to disinfect an air flow. The assembly 40 may be provided in combination with an air treatment device including negative and positive electrodes as described herein, where it may also act to reduce even further the amount of ozone, if any, leaving the device. The assembly includes one or more sources 42 of UV radiation. They are located within conduit 12, which may be downstream of the high voltage components shown in Figure 1. The UV sources are in the form of elongate tubes which extend longitudinally along the conduit and are spaced from its inner wall. Two tubes 42 are used in the example depicted in Figure 4.

Reflectors in the form of mirrors 44 are mounted on the inner wall of the conduit 12 and surround the UV sources. The mirrors reflect UV light incident thereon back into the interior of the conduit to increase the intensity of the UV radiation within the volume through which the air flows.

The UV sources are configured to emit radiation in order to kill viruses and bacteria.

The UV radiation is preferably in the range 200 to 280nm, and more preferably in the range of 240 to 280nm (and may be restricted to only be at or above 240nm and may also be restricted to only be at or below 280nm), to decompose ozone remaining in the gas flow.

The power rating of the UV sources is selected with reference to the conduit size and flow rate of air to be treated, with a higher flow rate requiring a higher power. For example, each source may have a power rating in the range 10 to 60W and more preferably in the range 50 to 55W. Preferably, the sources use at least 85W to generate UVC radiation (that is, radiation in the wavelength range of 200 to 280 nm).

io Figure 5 shows another arrangement 48 for exposing the air flow through the device to UV radiation. It includes a housing 50 which defines a chamber 52. The dimensions of the chamber may be 980x436x660mm for example. The chamber surrounds a plurality of elongate UV light sources 42. The housing has a chamber inlet 54 which in the device is in fluid communication with the air outlet of the conduit. The housing also has a chamber outlet 56 for allowing treated air to flow out of the chamber.

In the example shown in Figure 5, the light sources are arranged with their longitudinal axes parallel. The chamber inlet and outlet and the light sources are arranged such that portions (and preferably the majority) of the air flow path from the inlet to the outlet extend transversely with respect to the longitudinal axes of the UV light sources. In the example illustrated, five UV light sources are provided, with their longitudinal axes lying in a common plane.

The chamber inlet and outlet may be located towards opposite ends of the UV light sources and on opposite sides of the UV light sources (in directions parallel to the common plane of the light sources). This tends to increase the turbulence of the air flow from the inlet to the outlet, increasing the amount of time taken for the air flow and therefore the exposure of the air flow to the UV light.

Baffles 58 and 60 may be located within the chamber to increase further the time taken for the air flow from the chamber inlet to the chamber outlet and hence increase the exposure of the air flow to the UV light. Each baffle extends partway across the chamber so as to define an air flow path from the chamber inlet to the chamber outlet which meanders through the chamber. Each baffle may extend in a transverse direction with respect to the longitudinal axes of the UV light sources. Baffles 58 and 60 extend from opposite sides of the chamber.

In examples described herein, "substantially equal" may mean one value being within 5% of another, and substantially parallel may mean one direction being within 5° of another.

Claims

Claims An air treatment device comprising: an air inlet; an air outlet; a conduit defining an air flow path between the air inlet and the air outlet; a negative electrode in the conduit; a positive electrode in the conduit and downstream of the negative electrode; and io a voltage supply coupled to the negative and positive electrodes and configured to generate a negative voltage with a magnitude of at least 5kV at the negative electrode and a positive voltage with a magnitude of at least 5kV at the positive electrode to decompose molecules of ozone in air flowing along the conduit past the positive electrode.
2. A device of claim 1, wherein the voltage supply is configured to generate a negative voltage with a magnitude of at least 10kV at the negative electrode and a positive voltage with a magnitude of at least 10kV at the positive electrode.
3. A device of claim 2, wherein the voltage supply is configured to generate a negative voltage with a magnitude of at least 25kV at the negative electrode and a positive voltage with a magnitude of at least 25kV at the positive electrode.
4. A device of any preceding claim, wherein the positive electrode has a larger surface area than the negative electrode.
A device of any preceding claim, wherein the positive electrode is longer than the negative electrode, with the length of each electrode measured in the direction of the air flow path past the electrode.
6. A device of any preceding claim, wherein each of the negative and positive electrodes comprises a mesh formed of conductive material.
7. A device of any of claims 1 to 5, wherein each of the negative and positive electrodes comprises a rolled sheet of conductive material, with adjacent layers of the material spaced apart.
8. A device of any preceding claim, including a UV light source upstream of the negative electrode or downstream of the positive electrode.
9. An air treatment device comprising: an air inlet; io an air outlet; a conduit defining an air flow path between the air inlet and the air outlet; and a UV light source in the conduit for irradiating air flowing through the conduit with UV light.
10. A device of claim 8 or claim 9 including a reflector carried by the conduit for reflecting UV light from the light source back towards the interior of the conduit.
11. A device of any of claims 8 to 10, wherein the UV light source is configured to emit UV light in the range 240 to 280 nm.
12. A device of any of claims 8 to 11, wherein the conduit is tubular and the UV light source is elongate and extends longitudinally along the conduit.
13. A device of any of claims 8 to 12 wherein: the conduit includes a chamber, the chamber surrounds a plurality of elongate UV light sources having respective longitudinal axes, the chamber has a chamber inlet and a chamber outlet, an air flow path is defined between the chamber inlet and the chamber outlet, $0 and the longitudinal axes of the UV light sources are orientated transversely with respect to portions of the air flow path from the chamber inlet to the chamber outlet.
14 A device of claim 13, wherein the chamber includes at least one baffle which extends partway across the chamber in a transverse direction with respect to the longitudinal axes of the UV light sources
15. A vehicle including a device of any preceding claim for treating air flowing to an interior passenger space of the vehicle.