Air purification system

Abstract

A portable or handhold air cleaning system, whose air flow pipeline made of highly reflective and low absorptive material for UVC or UVB light acts also as a UV light waveguide, is invented. The system features a TEC cooled LED light source; air flow warm up mechanism; and UV light absorption/air cleaning enhancement device. The system is useful for travellers and office workers during flu and hay-fever seasons.

Claims

1. A portable or handhold air purification system comprises at least: An air flow pipeline, with an air inlet and an air outlet, which carries an air flow taken from ambient air and is made of or its internal surface is made of a highly reflective material with low light absorption for ultraviolet c-band (UVC) and/or ultraviolet b-band (UVB); An ultraviolet c-band light emitting diode (a UVC LED) or a ultraviolet b-band light emitting diode (a UVB LED) as a ultraviolet light source emitting a batch of light into the air flow pipeline, inside which the air flow is cleaned via a ultraviolet light exposure; and A thermoelectric cooler (TEC) attached on said ultraviolet light source and mounted on a heat sink to keep the working temperature of the ultraviolet light source within a predetermined safe range via an accelerated heat dissipation.

2. The system of claim 1, wherein said batch of light emitted from said ultraviolet light source first passes through an ultraviolet light waveguide, which is made of a highly reflective material with low light absorption for ultraviolet c-band and/or b-band before injected into said air flow pipeline.

3. The system of claim 2, wherein said ultraviolet light waveguide is split a least into a couple of light paths—one for light injection near the air inlet, the other for light injection near the air outlet, to increase light exposure time and dosage for everything through the air flow pipeline.

4. The system of claim 1, wherein said air flow pipeline has an air path middle point, around which there is at least an extra feature, which is made of or whose surface is made of a highly reflective material with low light absorption for UVC and/or UVB, inside said air flow pipeline to further assist purification of said air flow through interaction with said batch of light.

5. The system of claim 4, wherein said extra feature is a group of planes, which partially block the air flow to act as an air flow buffer and reflect an incoming UV light from their surface to form an area with a light entanglement with the air flow.

6. The system of claim 4, wherein said extra feature is a group of planes which partially block the air flow and has a layer of photocatalyst nano particles absorbing a batch of incoming UV light to clean the air flow via either a photocatalytic effect or a photoelectrochemical oxidization effect.

7. The system of claim 1, wherein said air flow pipeline further comprises at least a device made of a group of inserted planes, on which there is at least a layer of electrically-separated nano particles of a metal for generating plasmonic resonance to either locally raise temperature high enough via plasmonic photothermal effect or produce an enhanced UVC and UVB light locally via plasmonic light enhancement effect, to assist the purification of said air flow.

8. The system of claim 7, wherein said group of inserted planes are made of or whose surface is made of a highly reflective material with low light absorption for UVC and/or UVB.

9. The system of claim 7, wherein said metal is either Al, or Ga, or Rh, or Mg, or Ag, or the combination of above mentioned metal either as an alloy or a composite.

10. The system of claim 7, wherein said device is placed either around a middle point of the air flow pipeline and/or near the air outlet inside the air flow pipeline.

11. The system of claim 1, wherein said heat sink for said TEC thermally connects to a heat radiator outside the air flow pipeline to raise the temperature of the air flow coming out from the air outlet above that of ambient air, which provides an expel force to surrounding ambient air.

12. The system of claim 11, wherein said expel force to surrounding ambient air keeps untreated ambient air away and leaves a user of the system with only a steam of purified air.

13. The system of claim 1, wherein said air flow pipeline has an activated carbon filter near said air outlet inside said air flow pipeline to remove a trace amount of ozone in said air flow before reaching said air outlet.

14. The system of claim 1, wherein said highly reflective material with low light absorption is either PTFE film and/or PTFE tube; or ePTFE (expanded PTFE) film or tube; or porous PTFE film or tube; or Nitrocellulose film; or low UV absorption Nitrocellulose paint; or Teflon® tape/film and/or Teflon® tube; or Aluminum foil and/or tube; or Tetratex® film and/or Tetratex tube from Tetratec Corp (with its main composition as ePTFE); or 3M™'s enhanced spec reflector (ESR) film/sheet (made of multi-layer polymer); or Dupont™'s Tyvek® paper (made of high density polyethylene fibers); or Dupont™'s Melinex® film/sheet (polyester); or Toray's Lumirror™ sheet (polyester).

15. The system of claim 1, wherein said portable or handhold air purification system has an electrical power management system to allow the system to work based on electric power from either a built-in rechargeable battery, or a USB connection, or a main electrical outlet.

16. The system of claim 1, wherein said portable or handhold air purification system has a device to measure and monitor the light intensity from said ultraviolet light source.

17. The system of claim 1, wherein said portable or handhold air purification system has an internal clock system to record total system-turn-on time or system usage time against a predetermined system lifetime for maintenance.

18. The system of claim 1, where said portable or handhold air purification system has a display method or an app (software) linked to its users' smart phone to provide a system health report and also give a warning for an incoming system maintenance.

19. The system of claim 6, where in said layer of photocatalyst nano particles is a layer of either Titanium dioxide (TiO2), or Zirconium oxide (ZrO), or Zinc oxide (ZnO), or Magnesium oxide (MgO), or tungsten trioxide (WO3), or the combinations of the above mentioned photocatalyst with or without addition of a small amount nano particles of a precious metal—either Pt, or Au, or Rd, or Rh, or Ru.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 a schematic embodiment of the portable or handhold system proposed in this invention to use UVC or UVB LED for air purification.

(2) FIG. 2 one of the embodiment of UV photons entanglement structure also acting as an air flow buffer.

(3) FIG. 3 an embodiment of another design with air flow path reduction, UV entanglement structure and plasmonic feature in the system.

DETAILED DESCRIPTION

(4) The following numerous specific detail descriptions are set forth to provide a thorough understanding of various embodiments of the present disclosure. It will be apparent to one skilled in the art, however, these specific details need not be employed to practice various embodiments of the present disclosure. In other instances, well known components or methods have not been described.

(5) FIG. 1 shows a schematic embodiment of the proposed handhold system in this invention. As mentioned previously, the design principle of the proposed system is to allow everything in the air flow to experience maximum UV exposure from the air inlet to air outlet by using the air flow pipeline as a UVC/B light waveguide based on the reflection from the internal surface of the air pipeline made of UVC/B highly reflective and low absorption material(s). For the purpose of simplicity, in FIG. 1, only the internal surface of the air pipeline is shown and represented here. Having said that, the highly UVC/B reflective material for internal surface of the air flow pipeline and the body of the air flow pipeline can certainly be the same materials such as Polytetrafluoroethylene (PTFE). As shown, the whole air pipeline at least the internal surface made of highly UVC/B reflective material has a sealed end indicated here as 101. Ambient air 102 shown here as a arrow is taken into the system from the air inlet with an air filter 103 either from an air pump or a blow-in fan. The air filter built in the air inlet is just a low grade filter to prevent dust in the air into the system. The air flow inside the system shown here as 104, represented by the broken lines, goes through the whole air flow pipeline and reach to the air outlet 105 indicated by another arrow 106. The whole air flow pipeline presented here as a U shape with the dotline 107 indicating that the whole pipeline can be much longer than what is being shown here.

(6) The light injection into the system is from two UVC/B LEDs 108. For the simplicity of drawing, two UVC/B LEDs are shown here. Nevertheless, a single LED can certainly be used in the system with proper design of the reflection from the internal surface of the waveguide for splitting the beam (batch of light) from one LED into two similar paths as indicated here in FIG. 1. In fact, using one UV LED saves power and make the heat dissipation relatively easier, which is particularly important for handhold device. Nevertheless, with main power outlet available on modern airplanes and trains, even for personal handhold air purification device, power may not be a limited factor here. The UVC/B (much more preferable UVC due to the main DNA absorption peaking at 260 nm) LED(s) 108 sits on its own package mostly with a heat sink 109. A thermoelectric cooler TEC 110 is used and mounted over the LEDs's own heat sink 109 to assist the heat dissipation of the LED 108. The TEC is also thermally connected to its own heat sink 111, which also links to a heat spreader/radiator 112 surrounding and being out the air flow pipeline. The heat spreader/radiator 112 helps to warm up the air 106 out from the air outlet 105, which helps to provide warmer air than that of ambient air to the user. The warmer air also has a higher pressure than that of the ambient air therefore provide an expel force pushing the colder ambient air away from the user and makes the post-purified air from the system become the solo air source for the user(s).

(7) The UVC/B light 113 emitting from the LED 108 is also surrounded by UVC/B waveguide 114 made of UVC/B highly reflective materials with low light absorption, and is guided and split into the air inlet branch and air outlet branch to purify the air flow 104 at both branches. The batch of arrows 115 indicated the UVC/B, at the air inlet branch, bounced by the internal reflection of the waveguide 114 and the internal surface of air flow pipeline 101 while the branch of arrows 116 indicated those at the air outlet branch experience similar reflection. It is worth to note the two branch of arrows or UV light will eventually meet around the middle point of the air flow path 117. Near the middle point of the air flow path 117, there are some special structures and or functional features to further enhance the air purification and cleaning, which will be discussed in the following sections.

(8) As shown in FIG. 1, near the air outlet 105, there are also a couple of functional features: 119 is a plasmonic device made of UVC/B highly reflective material, on which there is specially fabricated electrically isolated metal nano particles being able to generate plasmonic resonance at the UVC and low UVB wavelength; near the air outlet 105, 120 is an activated carbon filter, whose function is to remove any trace of ozone, which could be produced or already existing in the incoming air flow. It also help to remove any odor, if there is any, from the incoming air flow and it is the last safeguard before the purified air reaching its user(s).

(9) There are quite a few choice of materials for UVC/B with high reflection and low absorption. They are general PTFE film or tube (eg. those from Gore); or ePTFE (expanded PTFE) film or tube; or porous PTFE film or tube; film of Nitrocellulose; or even Nitrocellulose pain with special components (without those for high UVC/B absorption); Teflon® tape/film and tube; Aluminum foil or tube; Tetratex® film or tube from Tetratec Corp (with its main composition as ePTFE); 3M™'s enhanced spec reflector (ESR) film/sheet (made of multi-layer polymer); Dupont™'s Tyvek® paper (made of high density polyethylene fibers) or Melinex® film/sheet (polyester); or Toray's Lumirror™ sheet (polyester).

(10) For material used for the plasmonic device, nano particles in the size range from 5 nm-100 nm from Aluminium (Al) with AlOx, Ga, even more expensive Rh, or their combinations as an alloy system or an composite system for plasmonic resonance within UVC/B wavelength.

(11) FIG. 2 shows one of the embodiment of cross-section view for the UV photons entanglement structure also acting as air flow buffer shown as 118 near the middle point of the air flow path 117 in FIG. 1. In this specially designed structure in the pipeline 200, just as shown in FIG. 1, the internal surface of the air pipeline 201 is made of highly UVC/B reflective and low UVC light (and/or UVB light) absorption materials, the structures 202 are planes also made of highly reflective and low UVC light (and/or UVB light) absorption materials, which is inserted into the air flow pipeline. The arrangement of the planes 202 still allows the air flow 203 to pass from left to right in this particular illustration but it will slow down the air flow speed to allow more dwell time of the air flow in this area. The incoming bounced UV light from left 204 and from right 205 all will be reflected multiple times, as represented by the solid arrows, by these planes at various locations while they try to find a way proceed. The dot lines of 207 indicates that the reflection will continue till all the light energy is fully absorbed by the materials during the propagation of UVC/B light in the air flow pipeline or absorbed by any pollutant or bioaerosols in the air flow. The whole structure 200 allows air flow and tangled UVC/B photons interact more thoroughly therefore effectively increase the opportunity of UVC/B exposure for any pollutant in the air flow. For any pollutant in the air flow, the overall UVC/UVB dosage which it exposes is the total UVC/B light it experiences after it gets into the system at air inlet before it gets out at the outlet. The longer it stays within the air pipeline, the higher the local UVC/B light intensity is, the higher the dosage it will see for any pollutant in the air stream. The structure 200 literally acts as a local UV light enhancement features via light entanglement (also with air flow) due to the reflection as well as extend the time for any pollutant exposed under the UV light.

(12) FIG. 3 shows an embodiment of another design with cross section reduction of the air flow path, UV entanglement structure, and a plasmonic feature near the middle point of the air flow path 117 in FIG. 1 in the system. The design 300 has the internal surface of the air pipeline 301 made of highly UVC/B reflective and low UVC (and/or UVB) light absorption materials. As shown, the cross section of the air flow pipeline 301 is larger at the both ends and smaller in the middle of air flow pipeline. As such, the air flow is forced to reduce it cross section dimension while the air flow speed gets increased. The increase of air flow speed helps the flow go smoothly through the feature 302, which is made of either thin film with pass through channels with predetermined size (eg. certainly larger than 320 nm—upside of the UVC/UVB wavelength) or porous films of the highly reflective materials for UVC/B beams (batch of light) from both left 303 and right 304. The channels size varies in such a way that the closer to the center, the smaller the size. The ideas is that the air can flow through the the channels with greatly reduced cross section while the UVC/B photons can pass through the channels but get entangled in this areas due to multiple reflection induced light bouncing to provide more interactions with any pollutant in the air flow. Therefore, this provides chance for any pollutant to see more UVC/B dosage when it goes along with the air flow from air inlet to the outlet. The longer the UVC/B LED is on, the higher the intensity of the UC/B light within the feature 302. As shown in FIG. 3, there is another devices 305, which locates near the middle of the air flow path. It is arranged similar as what has been shown in FIG. 2.

(13) In one case, the device 305 is made of electrically isolated metal nano particles (NPs), which can generate plasmonic resonance at the wavelength of UVC/B, deposited on highly UVC/B reflective film or substrate. The incoming UVC/B light will generate plasmonic resonance within these NPs, which can either heat up the NPs (plasmonic photothermal effect) or produce enhanced UVC/B light (plasmonic light enhancement effect) at the interface between the metal NPs and air. Metals such as Al, Ga, Rh, or their combination either as an alloys or a composite is capable of doing such tricks. Photothermal effect can raise the local temperature to significant high enough to deactivate some organic materials while the light enhancement effects products much stronger UVC/B light around the edge particularly the sharp corner of metal NPs (as antennas), which can boost local UVC/B dosage dramatically.

(14) In another case, photocatalyst NPs, such as Titanium dioxide (TiO2), or Zirconium oxide (ZrO), or Zinc oxide (ZnO), or Magnesium oxide (MgO), or tungsten trioxide (WO3), or the combinations of the above mentioned photocatalyst along with or without small amount of addition of precious metal such as Pt, Au, Ru, Rd, Rh, is deposited on UV highly reflective and low UVC/B absorptive solid film or porous film. The UVC/B induced photocatalyst effect (if the incoming air is dry) or PECO effects (if the incoming air has high moisture) can further assist the air purification for the system. It is worth to note that our proposal here is different from the normal PECO systems in the market, which uses UVA light and also the catalyst particles is deposited on air filter(s). Here, the proposal catalyst is deposited on high UVC/B reflective and low UVC/B absorptive substrate to enhance the interaction between the photons and NPs of photocatalyst. Also the designed system expect to work well for dry air with low humidity based on photocatalyst effect alone.