PHOTOCATALYTIC AIR TREATMENT SYSTEM AND METHOD

A photocatalytic air treatment system, including apparatuses and methods, for killing and/or mineralizing bacteria, viruses, mold, fungi, spores, mycotoxins, allergens, and other similar microorganisms or agents, and for oxidizing volatile organic compounds (VOCs). The system comprises one or more reactor beds configured in one or more stages with each reactor bed including a plurality of photocatalyst coated media substantially surrounding a plurality of sheathed ultraviolet light sources that may be arranged in a plurality of configurations. Adjacent ultraviolet light sources are positioned so as to create killing zones of photocatalyst coated media therebetween that are irradiated with ultraviolet light from multiple sources and in which an increased number of hydroxyl radicals are present. The photocatalyst generally comprises titanium dioxide, but may include one or more enhancers. The media is formed from or is coated with a material that induces the photocatalyst to form a nano-particle structure.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings in which like numerals represent like elements or steps throughout the several views,FIG. 1displays a schematic, top plan view of a photocatalytic air treatment system100, according to a first exemplary embodiment of the present invention, for treating air by killing and/or mineralizing bacteria, viruses, mold, fungi, spores, mycotoxins, allergens, and other similar microorganisms or agents, and for oxidizing volatile organic compounds (VOCs), that may be present therein. The photocatalytic air treatment system100comprises a reactor bed102, an air-handling unit104, and a transition member106interposed between and connected to the reactor bed102and the air-handling unit104. The air-handling unit104is adapted to pull untreated air108(i.e., indicated by arrows108) from the environment in which the photocatalytic air treatment system100is present or from another source and to direct the untreated air108into the reactor bed102via the transition member106. Generally, the air-handling unit104comprises a fan or blower that directs, or blows, untreated air108into the reactor bed102at a static pressure and volumetric flow rate selected and sufficient to overcome the static pressure drop caused by the reactor bed102during flow therethrough, to produce a desired volumetric rate of treated air110(i.e., indicated by arrows110) exiting the system100, and to achieve a desired quality of air treatment as determined by measuring (e.g., in parts per million (ppm) or parts per billion (ppb)) the quantity of killed, mineralized, or oxidized bacteria, viruses, mold, fungi, spores, mycotoxins, allergens, other similar microorganisms or agents, and volatile organic compounds (VOCs) present in the treated air110relative to the quantity of the same present in the untreated air108. The transition member106is configured to direct untreated air108exiting the air-handling unit104into the reactor bed102for treatment. Generally, the transition member106comprises a plenum, duct, or similar structure configured to direct and distribute the untreated air108into the reactor bed102in a manner that provides a substantially equal flow of untreated air108to all parts of the reactor bed102. It should be noted that in some embodiments of the present invention, the air-handling unit104is connected directly to the reactor bed102absent any transition member106therebetween. It should also be noted that in some embodiments of the present invention, the air-handling unit104may be positioned relative to the reactor bed102and operated in a manner that induces a flow of untreated air108through the reactor bed102instead of forcing a flow of untreated air108through the reactor bed102.

The photocatalytic air treatment system100may further comprise, as illustrated inFIG. 1, a heating element112adapted to heat the untreated air108prior to its entrance into the reactor bed102. Generally, the heating element112comprises an electric resistance heater, heating strip, or other suitable device for raising the temperature of the untreated air108above its temperature when entering the air-handling unit104. By raising the temperature of the untreated air108before it enters the reactor bed102, the reaction rate of the photocatalytic reaction (described in more detail below) is increased and the production of hydroxyl radicals (OH−) is also increased, thereby enhancing the probability that bacteria, viruses, mold, fungi, spores, mycotoxins, allergens, other similar microorganisms or agents, and/or volatile organic compounds (VOCs) will come into contact with a hydroxyl radical (OH−) and undergo an oxidation reaction that kills, mineralizes, or destroys same, as the case may be. Further, by raising the temperature of the untreated air108, the humidity level of the untreated air108, or relative humidity, is reduced and the reaction rate of the photocatalytic reaction is increased with similar effects resulting as those due to the increase in temperature of the untreated air108. It should be noted, however, that while the inclusion and operation of a heating element112is beneficial to the system's overall quality of air treatment, the photocatalytic air treatment system100need not include a heating element112in order to achieve substantial reductions in the quantities of volatile organic compounds (VOCs) and/or live, reproducible bacteria, viruses, mold, fungi, spores, mycotoxins, allergens, and other similar microorganisms or agents present in the treated air110exiting the system100.

According to the present embodiment, the reactor bed102comprises an enclosure120and a plurality of photocatalyst coated media122that are contained by and within the enclosure120. Notably, the photocatalyst coated media122are arranged within the enclosure120in a substantially random manner such that air passing through the reactor bed102collides with, or comes into contact with, many photocatalyst coated media122, thereby increasing the amount of time that bacteria, viruses, mold, fungi, spores, mycotoxins, allergens, other similar microorganisms or agents, and volatile organic compounds (VOCs) present in the untreated air108are in contact with the photocatalyst coated media122and increasing the system's ability to kill, mineralize, or oxidizing the same. The photocatalyst coated media122are also arranged within the enclosure120so as to increase the number of photons of ultraviolet light that strike them. Each photocatalyst coated media122includes a substrate media that is coated, at least in part, with a photocatalyst substance on the surface thereof that undergoes a photocatalytic reaction when exposed to ultraviolet light. The photocatalytic reaction produces hydroxyl radicals (OH−) on the surface of the substrate media that are available to combine, in an oxidation reaction, with bacteria, viruses, mold, fungi, spores, mycotoxins, allergens, other similar microorganisms or agents, and volatile organic compounds (VOCs) present in the untreated air108. Generally, in the exemplary embodiments described herein, the photocatalyst substance comprises titanium dioxide (TiO2), but may also comprise other substances alone or in combination with the titanium dioxide (TiO2) in other embodiments. Thus, the photocatalyst substance may further comprise an enhancing substance (sometimes referred to herein as an “enhancer”) that increases the reaction rate of the photocatalytic reaction, thereby causing the production of an increased number hydroxyl radicals available for an oxidation reaction as described above. In the exemplary embodiments described herein, the photocatalyst substance may further comprise an enhancer including zirconium dioxide (ZrO2) in a quantity of about ten percent (10%) of the total photocatalyst substance. It should be noted, however, that the scope of the present invention includes the incorporation and use of enhancing substances other than zirconium dioxide (ZrO2).

The substrate media of the plurality of photocatalyst coated media122are selected to have shapes or forms providing a substantial amount of surface area for coating with a photocatalyst substance and for supplying sites for hydroxyl radicals (OH−) to be exposed to untreated air108flowing through the reactor bed102. By utilizing substrate media having shapes that provide maximal surface area, the amount of photocatalyst substance that is applied to and present on the substrate media is increased relative to the amount that may be applied to other shapes with complementary increases occurring in the number of hydroxyl radicals (OH−) that are created by the photocatalytic reaction of the photocatalyst substance with ultraviolet light and in the number of hydroxyl radicals (OH−) that are actually contacted by and undergo an oxidizing reaction with bacteria, viruses, mold, fungi, spores, mycotoxins, allergens, other similar microorganisms or agents, and volatile organic compounds (VOCs) present in the untreated air108. In accordance with the exemplary embodiments described herein, the substrate media are all generally of a tubular shape or form somewhat similar to macaroni and are coated at least partially with a photocatalyst substance on inner and outer surfaces thereof, thereby providing a substantial amount of surface area for the creation, residence, and reaction of hydroxyl radicals (OH−). In other exemplary embodiments of the present invention, the substrate media of the photocatalyst coated media122may have a cylindrical, spherical, toroidal, polyhedrical, or other shape or form. Furthermore, in other exemplary embodiments of the present invention, the substrate media of the photocatalyst coated media122may have a plurality of different shapes or forms.

In the exemplary embodiments of the present invention described herein, the substrate media of the plurality of photocatalyst coated media122are formed from a material that does not react with (e.g., is inert relative to) the photocatalyst substance applied thereto and that, perhaps, more importantly induces the applied photocatalyst substance to thereto a nano particle structure atop the surface(s) of the substrate media instead of forming only a closely-packed layer. By virtue of the photocatalyst substance forming a nano-particle structure, the number of potential sites and surface area for photocatalysis to occur and for the concomitant creation of hydroxyl radicals (OH−) and their contact with and oxidation of bacteria, viruses, mold, fungi, spores, mycotoxins, allergens, other similar microorganisms or agents, and volatile organic compounds (VOCs) is dramatically increased over the number of potential sites and surface area that would otherwise be available for such to occur if the material of the substrate media did not induce the formation of a nano-particle structure. Generally, the material of the substrate media of the described exemplary embodiments comprises bora silica glass, but other materials capable of causing the applied photocatalyst substance to form a nano-particle structure are also considered to be within the scope of the present invention. It should also be noted that the scope of the present invention includes other materials for substrate media that are normally reactive with the photocatalyst substance applied thereto, but that are pre-coated with another substance that renders them non-reactive with the photocatalyst substance prior to coating them with the photocatalyst substance. Such reactive materials include, for example and not limitation, materials commonly classified as plastics, metals, and ceramics.

According to the present invention, the photocatalytic air treatment system100further comprises a plurality of ultraviolet light sources124that are positioned so as to emit photons of ultraviolet light at the photocatalyst coated media122and at the photocatalyst substance thereof; thereby causing a photocatalytic reaction of the photocatalyst substance to occur, hydroxyl radicals (OH−) to be generated by the photocatalytic reaction, and oxidation reactions of the hydroxyl radicals (OH−) and bacteria, viruses, mold, fungi, spores, mycotoxins, allergens, other similar microorganisms or agents, and volatile organic compounds (VOCs) present in the untreated air108to occur. The ultraviolet light sources124are generally adapted to produce light having one or more wavelengths entirely within the ultraviolet portion (e.g., wavelengths less than 400 nm) of the electromagnetic spectrum. However, the scope of the present invention should be understood as including ultraviolet light sources124that may produce other light having one or more wavelengths that are outside of or otherwise not within, the ultraviolet portion (e.g., wavelengths greater than 400 nm) of the electromagnetic spectrum. Also, the ultraviolet light sources124are generally embodied in the present invention in the form of elongated, tubular, T5 lamps or bulbs that generate ultraviolet light having a wavelength within a range of about 240 nm to 260 nm with an irradiance within a range of approximately 20 μW/cm2to 30 μW/cm2. However, it should be understood that the scope of the present invention includes ultraviolet light sources124that generate ultraviolet light having an irradiance greater than 1 μW/cm2. According to the exemplary embodiments described herein, the ultraviolet light sources124are preferably adapted to produce light having one or more wavelengths within the UVC bandwidth of the electromagnetic spectrum, but may include one or more wavelengths within the UV-A, UV-B, and/or UVC bandwidths of the electromagnetic spectrum.

In other embodiments within the scope of the present invention, the ultraviolet light sources124may produce different levels of irradiance and may be embodied in other forms, including, for example and not limitation, ultraviolet lamps or bulbs having non-tubular or other shapes, and ultraviolet light emitting diodes (LEDs). In still other embodiments within the scope of the present invention, the ultraviolet light sources124may be replaced by other devices such as lamps or bulbs other than ultraviolet fluorescent lamps or bulbs, non-ultraviolet light emitting diodes (LEDs), waveguides that direct ultraviolet light and/or other forms of energy at the photocatalyst coated media122, mercury vapor lamps (and, more particularly, high-pressure mercury vapor lamps), and microwave sources that are operable to produce a similar amount of energy as ultraviolet light sources124and/or that are operable to impart a sufficient amount of energy to the photocatalyst substance in order to cause photocatalysis and the above-described photocatalytic reaction of the photocatalyst substance to occur. It should be noted that the scope of the present invention also includes reactor beds102having any number of lamps and/or bulbs, lamps and/or bulbs having the same or different sizes in terms of diameter and length, lamps and/or bulbs having the same or different wattages, and/or any combination of the foregoing.

In the exemplary embodiments of the present invention described herein, the reactor bed102further comprises a plurality of sheaths126for receiving the ultraviolet light sources124therein and for separating the ultraviolet light sources124from the photocatalyst coated media122that substantially surround the sheaths126and ultraviolet light sources124. By separating the ultraviolet light sources124from the photocatalyst coated media122with intermediate sheaths126, the ultraviolet light sources124may be inserted into and removed from the reactor bed102(i.e., inserted and removed from the sheaths126) without coming into contact with the photocatalyst coated media122, thereby making replacement of the ultraviolet light sources124much easier and less time consuming whenever such replacement is necessary. The sheaths126are generally formed from a quartz, or quanz-like, material that enables ultraviolet light from the ultraviolet light sources124to pass therethrough substantially unaffected and that does not react with the photocatalyst substance of the photocatalyst coated media122in contact therewith. It should be noted that although the exemplary embodiments of the present invention described herein include a plurality of sheaths130, the scope of the present invention includes other exemplary embodiments that do not include such Sheaths130. It should also be noted that even though the photocatalytic air treatment system100of the present invention is illustrated herein via different embodiments having particular numbers of ultraviolet light Sources124and/or sheaths126, the scope of the present invention comprises other exemplary embodiments having different numbers and arrangements of ultraviolet light sources124and/or sheaths126.

The enclosure120of the reactor bed102is formed from a plurality of panels130that confine the photocatalyst coated media122within the enclosure120and that define a generally rectangular shape when viewed in top plan view as inFIG. 1. A first opposed pair of panels130A,130B respectively define an air inlet132and an air outlet134of the reactor bed102. Panel130A is generally formed from a perforated or mesh-like material suitable to confine the photocatalyst coated media122and is adapted to receive untreated air108from transition member106and to allow the received untreated air108to pass therethrough and into the reactor bed102. Panel130B is similarly formed from a perforated or mesh-like material suitable to confine the photocatalyst coated media122and is adapted to receive treated air110from the reactor bed102and to allow the received treated air110to pass therethrough and to exit the photocatalytic air treatment system100. Second and third opposed pairs of such panels130C,130D,130E,130F are generally formed from a material that it is not air permeable and are adapted to direct untreated air108from the air inlet132and through the reactor bed102in a predominant, or primary, direction (e.g., designated by arrows136) toward the air outlet134. It should be noted that in some exemplary embodiments, the reactor bed102and its enclosure120may comprise a removable chamber, or cartridge, that may be disconnected and/or removed from fluid communication with the transition member106and air handling unit104so that it can be replaced after the elapse of an appropriate period of time (for example and not limitation, one year) with a new or reconditioned removable chamber, or cartridge, having an identical or similar reactor bed102and enclosure120, and having new or refurbished ultraviolet light sources124, sheaths126, and/or photocatalyst coated media122. Additionally, it should be noted that in certain other embodiments, a removable and replaceable HEPA or % HEPA all-inclusive filter(s) may be connected in fluid communication with the reactor bed102and its enclosure120(whether comprising a removable chamber or not) generally at either the intake or exhaust thereof so that the air also passes through such filter(s) to receive further treatment and conditioning. In still other embodiments, a HEPA filter or % HEPA all-inclusive filter may be integral with the reactor bed102and enclosure120, thereby together defining and forming a removable and replaceable chamber or cartridge of the photocatalytic air treatment system100. It should be noted that in other embodiments, a HEPA filter or % HEPA all-inclusive filter(s) may be positioned at various other locations within the air flow path of the photocatalytic air treatment system100.

The sheaths126extend substantially between the second opposed pair of panels130C,130D at locations corresponding respectively to holes138,140defined by panels130C,130D. Each sheath126, according to the exemplary embodiments described herein, has a generally elongate sleeve-like shape with a longitudinal centerline142and is sized to receive a corresponding ultraviolet light source124therein having a longitudinal centerline144such that longitudinal centerlines142,144are substantially collinear. The holes138,140in respective panels130C,1301) have longitudinal centerlines146,148that are also substantially collinear with the longitudinal centerlines142,144of the respective sheaths126and ultraviolet light sources124. By virtue of such arrangement and alignment of respective sheaths126, holes138,140, and ultraviolet light sources124, the ultraviolet light sources124may be easily inserted into and removed from the sheaths126as necessary for assembly, disassembly, and/or maintenance.

In accordance with the exemplary embodiments of the present invention, the sheaths126and ultraviolet light sources124are arranged in a single row with the centerlines142,144of the sheaths126and ultraviolet light sources124defining angles, α, with the primary direction136of air travel through the reactor bed102. All of the angles, α, generally (but not necessarily) have substantially the same angular measure and such angular measure is typically between zero degrees (0°) and one hundred eighty degrees (180°). According to the first exemplary embodiment depicted byFIGS. 1 and 2, the angles, α, have an angular measure of approximately ninety degrees (90°) such that the primary direction of136of air travel through the reactor bed102is substantially perpendicular to the longitudinal centerlines142,144of the sheaths126and ultraviolet light sources124. By virtue of the primary direction136of air flow through the reactor bed102being substantially transverse to (and, in the first exemplary embodiment, substantially perpendicular to) the longitudinal centerlines142,144of the sheaths126and ultraviolet light sources124in the first exemplary embodiment, the sheaths126and ultraviolet light sources124act as obstructions, or baffles, to the flow of air through the reactor bed102, create air turbulence within the reactor bed102, and cause portions of the air attempting to flow through the reactor bed102in the primary direction136to be diverted into secondary directions (e.g., indicated by arrows150) (seeFIG. 2). By diverting portions of the air traveling through the reactor bed102into secondary directions150, the residence time of such air portions in the reactor bed102is dramatically increased and, consequentially, there is a substantial increase in the number of bacteria, viruses, mold, fungi, spores, mycotoxins, allergens, other similar microorganisms or agents, and volatile organic compounds (VOCs) present in such air portions that come into contact with and are oxidized by hydroxyl radicals (OH−) produced by the photocatalytic reaction and adhering to the photocatalyst coated media122.

As illustrated in the schematic, partial sectional view ofFIG. 3, the sheaths126of the reactor bed102are generally positioned adjacent to one another such that the corresponding ultraviolet light sources124therein are also generally positioned adjacent to one another and define a center-to-center distance, D1, therebetween having a measure in the range of about 1.25 inches to about 6 inches. In such an arrangement, portions of the photocatalyst coated media122reside between adjacent sheaths126and, hence, between adjacent ultraviolet light sources124. Further, many of such photocatalyst coated media122reside within an elongate volume152extending between adjacent ultraviolet light sources124and panels130C,130D in which the irradiance of the ultraviolet light154striking the members122therein corresponds to the combined irradiance of the ultraviolet light154emitted outwardly by the adjacent ultraviolet light sources124. Because the irradiance of the ultraviolet light154striking the photocatalyst coated media122within such elongate volumes152is higher than the irradiance of the ultraviolet light154striking photocatalyst coated media122not within such elongate volumes152, the number of hydroxyl radicals (OH−) created by the photocatalytic reaction is greater within such elongate volumes152and, hence, the number of bacteria, viruses, mold, fungi, spores, mycotoxins, allergens, other similar microorganisms or agents, and volatile organic compounds (VOCs) present in air passing through such elongate volumes152that come into contact with and undergo an oxidation reaction with hydroxyl radicals (OH−) is substantially greater. As a consequence, each such elongate volume152is sometimes referred to as a “killing zone”. Generally, in the exemplary embodiments described herein, each ultraviolet light source124is operable to produce ultraviolet light154having an irradiance greater than 5 μW/cm2and preferably in a range of approximately 20 μW/cm2to 30 μW/cm2. Thus, the irradiance of the ultraviolet light154striking the photocatalyst coated media122within such elongate volumes152is, typically, within a range of approximately 20 μW/cm2to 60 μW/cm2. It should be noted that the number of hydroxyl radicals (OH−) created by the photocatalytic reaction is proportional to the irradiance of the ultraviolet light154striking the photocatalyst coated media122within such elongate volumes152. Additionally, it should be noted that bacteria, viruses, mold, fungi, spores, mycotoxins, allergens, other similar microorganisms or agents may also be killed or rendered harmless simply by exposure to ultraviolet light from the ultraviolet light sources124.

FIG. 4displays a schematic, top plan view of a photocatalytic air treatment system100′ in accordance with a second exemplary embodiment of the present invention that is substantially similar to the first exemplary embodiment described herein. However, in the second exemplary embodiment, the plurality of ultraviolet light sources124′ and corresponding plurality of sheaths126′ are arranged within the reactor bed102′ in a row and column matrix160′ having multiple rows162′ and multiple columns164′. The row and column matrix160′ is more clearly illustrated in the schematic, sectional view ofFIG. 5. As illustrated, the rows162′ of ultraviolet light sources124′ and corresponding sheaths126′ define angles, β, with the columns164′ of ultraviolet light sources124′ and corresponding sheaths126′. Generally, all of the angles, β, have the same angular measure. Also generally, each angle, β, has an angular measure of ninety degrees (90°). It should be noted, however, that in other exemplary embodiments of the present invention, angles, β, may have, the same or different angular measures and/or angular measures other than ninety degrees (90°).

In a manner similar to that of the reactor bed102of the first exemplary embodiment, the primary direction136′ of travel through the reactor bed102′ is transverse to the longitudinal centerlines142′,144′ of the respective sheaths126′ and ultraviolet light sources124′, Notably, however, the row and column matrix160′ of ultraviolet light sources124′ and sheaths126′ of the second exemplary embodiment advantageously produces an increased number of obstructions, or baffles, to the flow of air through the reactor bed102′ than are present in the reactor bed102of the photocatalytic air treatment system100of the first exemplary embodiment. The row and column matrix160′ also advantageously results in the reactor bed102′ of the photocatalytic air treatment system100′ having an increased number of adjacent ultraviolet light sources124′ and an increased number of elongate volumes152′ extending between such adjacent ultraviolet light sources124′ and panels130C′,130D° in which the irradiance of the ultraviolet light striking the photocatalyst coated media122′ therein corresponds to the combined irradiance of the ultraviolet light emitted outwardly by such adjacent ultraviolet light sources124′. Due at least in part to the increased number of such elongate volumes152″, the arrangement of the ultraviolet light sources124′ of the photocatalytic air treatment system100′ of the second exemplary embodiment increases the number of bacteria, viruses, mold, fungi, spores, mycotoxins, allergens, other similar microorganisms or agents, and volatile organic compounds (VOCs) present in untreated air108′ that come into contact with and undergo an oxidation reaction with hydroxyl radicals (OH+), thereby increasing the number of the same that are killed, minerialized, and/or oxidized, as the case may be.

FIG. 6displays a schematic, tap plan view of a photocatalytic air treatment system100″ in accordance with a third exemplary embodiment of the present invention that is substantially similar to the second exemplary embodiment described herein. Similar to the photocatalytic air treatment system100′ of the second exemplary embodiment, the plurality of ultraviolet light sources124″ and corresponding plurality of sheaths126″ are arranged within the reactor bed102″ in multiple rows162″ and multiple columns164″ and the primary direction136″ of air flow through the reactor bed102″ is transverse to the longitudinal centerlines142″,144″ of the respective sheaths126″ and ultraviolet light sources124″. Also similarly, the longitudinal centerlines142″,144″ of the sheaths126″ and ultraviolet light sources124″ define angles, α, with the primary direction136of air flow through the reactor bed102″. Generally, the angles, α, have a measure of approximately ninety degrees (90°).

However, in the third exemplary embodiment and as is more clearly illustrated in the schematic, sectional view ofFIG. 7, the ultraviolet light sources124″ and sheaths126″ of the second row162A″ and offset relative to the ultraviolet light sources124″ and sheaths126″ of the first row162A″ by an offset distance, D2. Generally, the offset distance, D2, has a measure of approximately one-half of the center-to-center distance, D1, between the ultraviolet light sources124″ and sheaths126″ of the first row162A″. By offsetting the ultraviolet light sources124″ and sheaths126″ of the second row162B″, the level of turbulence in the air flowing through the reactor bed102″ is increased with more portions of the air traveling in secondary directions150″. Perhaps more importantly, the nearer adjacency of the ultraviolet light sources124″ of the second row162B″ to multiple ultraviolet light sources124″ of the first row162A″ produces an increased number of elongate volumes152″ between such ultraviolet light sources124″ and Within the reactor bed102″ in which the irradiance of the ultraviolet light striking the photocatalyst coated media122″ therein corresponds to the combined irradiance of the ultraviolet light emitted outwardly by such adjacent ultraviolet light sources124″. Because the arrangement of the ultraviolet light sources124″ increases the number of such elongate volumes152″ present within the reactor bed102″, the arrangement also increases the number of bacteria, viruses, mold, fungi, spores, mycotoxins, allergens, other similar microorganisms or agents, and volatile organic compounds (VOCs) present in untreated air108″ that come into contact with and undergo an oxidation reaction with hydroxyl radicals (OH−), thereby killing them, mineralizing them, and/or oxidizing them.

FIG. 8depicts a schematic, top plan view of a photocatalytic air treatment system100′″ for treating air according to a fourth exemplary embodiment of the present invention. As seen by viewingFIG. 8, the photocatalytic air treatment system100′″ comprises components substantially similar to those of the first exemplary embodiment described above. Thus, the photocatalytic, air treatment system100′″ comprises a reactor bed102′″, an air-handling unit104′″, and a transition member106′″ coupled between the reactor bed102′″ and air-handling unit104′″ for guiding the flow of untreated air108′″ from the air-handling unit104′″ into the reactor bed102′″. Similar to the reactor bed102of the first exemplary embodiment, the reactor bed102′″ of the fourth exemplary embodiment includes a plurality of sheaths126′″ for receiving a corresponding plurality of ultraviolet light sources124′″ therein and for separating the ultraviolet light sources124′″ from the photocatalyst coated media122′″ that substantially surround the sheaths126′″ and ultraviolet light sources124′″. However, in the fourth exemplary embodiment, the longitudinal centerlines142″,144″ of the sheaths126′″ and ultraviolet light sources124′″ are substantially parallel to the primary direction136′″ of air flow through the reactor bed102′″. As a consequence, a predominant portion of the untreated air108′″ entering the reactor bed102′″ travels through at least one elongate volume152′″ located between adjacent ultraviolet light sources124′″ and, therefore, a substantial number of bacteria, viruses, mold, fungi, spores, mycotoxins, allergens, other similar microorganisms or agents, and volatile organic compounds (VOCs) present in untreated air108″ come into contact with and are killed, mineralized, and/or oxidized by hydroxyl radicals (OH−).

FIG. 9displays a schematic, top plan view of a photocatalytic air treatment system100″″ in accordance with a fifth exemplary embodiment of the present invention. The photocatalytic air treatment system100″″ is substantially similar to that of the first exemplary embodiment, but includes multiple stages of air treatment instead of a single stage of air treatment as in the photocatalytic air treatment system100of the first exemplary embodiment. Due at least in part to the use of multiple stages of air treatment, the photocatalytic air treatment system100″″ of the fifth exemplary embodiment kills, mineralizes, and/or oxidizes larger numbers of bacteria, viruses, mold, fungi; spores, mycotoxins, allergens, other similar microorganisms or agents, and volatile organic compounds (VOCs) than the photocatalytic air treatment system100of the first exemplary embodiment.

In addition to similar components of the photocatalytic air treatment system100of the first exemplary embodiment, the photocatalytic air treatment system100″″ of the fifth exemplary embodiment comprises a first reactor bed102A″″ that is adapted to perform a first stage of air treatment and a second reactor bed102B″″ that is adapted to perform a second stage of air treatment. The first reactor bed102A″″ and second reactor bed102B″″ are connected by a coupling member170″″ for directing treated air110A″″ from the first reactor bed102A″″ into the second reactor bed102B″″ for further treatment. Generally, coupling member170″″ includes a plenum, duct, or other similar apparatus. Alternatively, in other exemplary embodiments, the first reactor bed102A″″ is abutted and directly connected to the second reactor bed102B″″ absent coupling member170″″.

In the photocatalytic air treatment system100″″, the first and second reactor beds102A″″,102B″″ each comprise a plurality of ultraviolet light sources124″″ and a corresponding plurality of sheaths126″″ having respective longitudinal centerlines144″″,142″″ that define angles, α, relative to the primary direction136″″ of air flow through the reactor beds102″″. Generally, each angle, α, has the same angular measure. Also generally, each angle, α, has an angular measure within a range of forty-five degrees (45°) to one hundred thirty-five degrees) (135°). Thus, the ultraviolet light sources124″″ and sheaths126″″ are oriented such that the primary direction136″″ of air flow through each reactor bed102″″ is substantially transverse to the longitudinal centerlines144″″,142″″ of the ultraviolet light sources124″″ and sheaths126″″, thereby creating air turbulence within the reactor beds102″″, causing air to flow in secondary directions150″″ within the reactor beds102″″, increasing the residence time for bacteria, viruses, mold, fungi, spores, mycotoxins, allergens, other similar microorganisms or agents, and volatile organic compounds (VOCs) within the reactor beds102″″, and increasing the number of the same that are killed, rendered non-reproducible, mineralized, and/or oxidized.

It should be noted that although the angular measure of angles, α, is generally the same in both reactor beds102″″ of the photocatalytic air treatment system100″″, the scope of the present invention includes other exemplary embodiments in which the angular measure of angles, α, is not the same. Therefore, the scope of the present invention includes photocatalytic air treatment systems100″″ in which the primary direction136″″ of the flow of air through one reactor bed102″″ is substantially transverse to the longitudinal centerlines144″″,142″″ of the ultraviolet light sources124″″ and sheaths126″″, while the primary direction136″″ of the flow of air through a second reactor bed102″″ is substantially parallel to the longitudinal centerlines144″″,142″″ of the ultraviolet light sources124″″ and sheaths126″″. Further, the scope of the present invention includes photocatalytic air treatment systems100″″ in which the primary direction136″″ of the flow of air through both reactor beds102″″ is substantially parallel to the longitudinal centerlines144″″,142″″ of the ultraviolet light sources124″″ and sheaths126″″.

Before proceeding with a description of a method of operation of the photocatalytic air treatment systems of the exemplary embodiments, it should also be noted that in other exemplary embodiments of the present invention, at least one pair of the ultraviolet light sources thereof have a distance therebetween that is different from the distance between the ultraviolet light Sources of other pairs of ultraviolet light sources of the plurality of ultraviolet light sources. Additionally, it should be noted that in other exemplary embodiments of the present invention, the plurality of ultraviolet light sources are arranged in different arrangements such that the time required for moving air to travel or pass by all of the ultraviolet light sources is increased relative to the time, required for moving air to travel or pass by all of the ultraviolet light sources of an arrangement thereof in which the plurality of ultraviolet light sources are positioned substantially in a single row or single column. By virtue of arranging the plurality of ultraviolet light sources in an arrangement that causes such an increase in the time required for air to travel or pass by all of the ultraviolet light sources, the number of collisions (or contacts) between bacteria, viruses, mold, fungi, spores, mycotoxins, allergens, other similar microorganisms or agents, and/or volatile organic compounds (VOCs) present in the air and the plurality of media of a reactor bed are also increased, thereby resulting in an increase in the number of bacteria, viruses, mold, fungi, spores, mycotoxins, allergens, other similar microorganisms or agents, and/or volatile organic compounds (VOCs) that are killed, rendered non-reproducible, mineralized, and/or oxidized.

In operation, the photocatalytic air treatment systems100,100,100″,100′″,100″″ of the various exemplary embodiments function according to substantially the same method. Therefore, although the following description is directed primarily to the photocatalytic air treatment system100of the first exemplary embodiment, it is generally applicable to the other exemplary embodiments as well. The photocatalytic air treatment system100is generally positioned within the environment in which air is to be treated and is connected to an appropriate electrical power supply. Once activated, the air-handling unit104pulls in untreated air108from the environment through its air intake and blows the untreated air108out through its exhaust and into the transition member106at an appropriate static pressure, velocity, and volumetric flow rate. While traveling though the transition member106, the untreated air108may be heated by heating element112in order to raise the temperature and reduce the relative humidity of the untreated air108. By increasing the air's temperature and reducing its relative humidity, the reaction rates of the photocatalytic and oxidation reactions occurring within the reactor bed102are increased, thereby resulting in an increased production of hydroxyl radicals (OH−) and an increased number of bacteria, viruses, mold, fungi, spores, mycotoxins, allergens, other similar microorganisms or agents, and volatile organic compounds (VOCs) being killed, mineralized, and/or oxidized, as the case may be.

The transition member106then directs the untreated air108through a HEPA filter (if one is present) and into the reactor bed102through the reactor bed's air inlet132. Once inside the reactor bed102, the untreated air108flows through the photocatalyst coated media122and toward the reactor bed's air outlet134in the primary direction136of air flow, However, as the untreated air108comes into contact with the sheaths126, portions of the untreated air108are deflected and redirected in secondary directions150and into the elongate volumes152of photocatalyst coated media122located between adjacent ultraviolet light sources124. In the elongate volumes152, the untreated air108comes into contact with photocatalyst coated media122that has been exposed to ultraviolet light having an irradiance corresponding to the combined irradiance of the ultraviolet light154emitted outwardly by the adjacent ultraviolet light sources124. Due at least in part to the photocatalyst coated media122of the elongate volumes152being exposed to a greater irradiance of ultraviolet light154, the photocatalyst coated media122therein host a greater number of hydroxyl radicals (OH−) to which bacteria, viruses, mold, fungi, spores, mycotoxins, allergens, other similar microorganisms or agents, and volatile organic compounds (VOCs) come into contact. Upon their contact, the hydroxyl radicals (OH−) react in an oxidation reaction with the bacteria, viruses, mold, fungi, spores, mycotoxins, allergens, other similar microorganisms or agents, and volatile organic compounds (VOCs), causing them to be killed, rendered non-reproducible, oxidized, and/or mineralized, as the case may be, and improving the quality of the untreated air108. It should be noted that the portions of the untreated air108that do not flow through an elongate volume152are also subjected to hydroxyl radicals (OH−) present on photocatalyst coated media122with similar results, but they are not subjected to the same highly concentrated numbers of hydroxyl radicals (OH−) that are present within the elongate volumes152. It should also be noted that the longer untreated air108is resident within the reactor bed102, there is an increased likelihood that the bacteria, viruses, mold, fungi, spores, mycotoxins, allergens, other similar microorganisms or agents, and volatile organic compounds (VOCs) therein will come into contact with hydroxyl radicals (OH−) and be killed, rendered non-reproducible, oxidized, and/or mineralized, thereby improving the quality of the treated air110.

After flowing through the photocatalyst coated media122, treated air110exits the reactor bed102through the reactor bed's outlet134and back into the environment of the photocatalytic air treatment system100. Of course, if the photocatalytic air treatment system100has multiple stages of air treatment, the untreated air108flows through multiple reactor beds102before being reintroduced into the environment, thereby resulting in increased air treatment.

The photocatalytic air treatment system100of the present invention may be utilized to treat air as described herein in a variety of applications. For example, in certain implementations, the photocatalytic air treatment system100or a variant thereof may be integrated into or used in connection with residential and commercial grade refrigerators, refrigeration systems, and wine coolers to treat the air present within refrigerated environments thereof, supplied thereto, and/or exhausted therefrom. In other implementations, the photocatalytic air treatment system100or a variant thereof may be incorporated into or utilized in conjunction with central and standalone air conditioning systems for residential and/or commercial use that may or may not include additional air handling units in order to treat the conditioned air supplied to residential and commercial rooms, buildings, facilities, and/or structures. In still other implementations, the photocatalytic air treatment system100or a variant thereof may be integrated into or used in connection with bathroom and/or vehicle air delivery, air exhaust, and/or air conditioning systems to treat air provided to and/or exhausted from bathrooms and/or the passenger compartments of vehicles and other mobile equipment. In still other implementations, the photocatalytic air treatment system100or a variant thereof may be incorporated into, attached to, or used with an air sanitizing module for an anesthesia machine to remove trace volatile organic compounds (VOCs) generated by anesthetic agents. In still other implementations, the photocatalytic air treatment system100or a variant thereof may be designed and integrated into an existing portable air purifying device used in hospitals. In still other implementations, the photocatalytic air treatment system100or a variant thereof may be incorporated into a ceiling or whole house fan for use in various rooms or structures, including infants' rooms, In still other implementations, the photocatalytic air treatment system100may be incorporated into or utilized with a hospital bed to provide onboard air treatment and/or purification. In yet other implementations, the photocatalytic air treatment system100or a variant thereof may be incorporated into or utilized in connection with cages or other enclosures used to house and/or transport animals to treat air supplied thereto and/or exhausted therefrom.

Whereas the present invention has been described in detail above with respect to exemplary embodiments thereof, it should be understood that variations and modifications might be effected within the spirit and scope of the present invention, as described herein before and as defined in the appended claims.