Low noise, ceiling mounted indoor air scrubber

In some embodiments, an indoor air cleaning apparatus and a method for removing at least a portion of at least one type of gas from an indoor airflow are disclosed. The apparatus may comprise a cabinet; at least one sorbent bank comprising at least one cartridge; a fan assembly comprising at least one housing including at least one housing inlet and at least one housing outlet, at least one motor and at least one impeller; and a heating element configured to operate in at least one of two modes: an active mode and an inactive mode; and a controller configured to operate in at least two modes: an adsorption mode and a regeneration mode.

FIELD OF THE DISCLOSURE

Embodiments of the present disclosure generally relate to air treatment and more particularly to scrubbing indoor air in buildings and homes.

BACKGROUND

Scrubbing indoor air is a useful technique for improving indoor air quality and eliminating or reducing the need for fresh air ventilation in buildings. Sorbents can be deployed in air treatment devices that receive indoor air, remove contaminants through contact with the sorbent, and return the treated air into the building directly or through an air circulation system. The sorbents can be regenerable, meaning that they further lend themselves to repeated use through temperature-swing adsorption, whereby upon saturation of the sorbent, a combination of heat and a purging air stream regenerates the sorbent's adsorption capacity.

In buildings with central air circulation, the location of these air treatment devices can be anywhere along the circulation path of the indoor air, including placing them in proximity to the central air handling system, on the roof, in a mechanical room or in a return air plenum.

The central location of the scrubber, which is due to the fact that air is circulating, has been essential to its practicality as an air quality solution for buildings. This allows the scrubber to be placed in unobtrusive places like a mechanical room or an air plenum, and with easy access to an exhaust outlet where it can purge contaminants during the regeneration cycle, and, in some cases, an outside air source to be used during regeneration to purge the sorbents.

In the absence of central circulation, scrubbing indoor air poses a unique challenge since a centralized or distant scrubber can no longer effectively address air quality in different locations in the building. Rather, scrubbers must be positioned in proximity of each targeted area or room and be configured with outside access for regeneration exhaust. Furthermore, if scrubbers are located in working or living spaces, it is important to minimize noise, physical imposition and any other disruptions, including filter replacements and other maintenance activities.

SUMMARY OF SOME OF THE EMBODIMENTS

There is thus provided according to some embodiments, a low profile, low noise, compact indoor air scrubber configured for cleaning indoor air, using in-situ regenerated sorbents to capture contaminant gases in the indoor air. The scrubber may have one inlet and two outlets, one outlet for clean air and the other for regeneration exhaust. Typically, the scrubber is attached to the ceiling or, where a drop ceiling is in place, it is positioned above the drop ceiling and is in fluid communication with the room via one, two or more short ducts or conduits that lead to openings or grilles in the drop ceiling. A separate flexible conduit leads from the exhaust outlet to an air passage outside the building, usually via a bathroom or kitchen exhaust, a smokestack, or a window in the building. The scrubber may comprise fans, dampers and/or heating means and well as electronic circuits. The electronic circuits may operate the fans, dampers and a built-in heater to control the scrubber's operating mode as it swings periodically from scrubbing (i.e. adsorption) to regeneration and back.

In some embodiments, there is provided a low-noise, low-profile air cleaning device, namely an indoor air scrubbing or gas adsorption apparatus, comprising one or more inlets, a first outlet, a second outlet, dampers to control the outlets, one or more fans, a heater coil, a sorbent bank, and an electronic control circuit, that can operate in at least two modes: adsorption and regeneration, where in adsorption mode, air enters through one or more of the inlets and exits through a first outlet after passing through the sorbent bank, such that at least one type of gas species is partially captured by the sorbent upon passing through the bank. In the regeneration mode, air enters through one or more of the inlets and exits through a second outlet, after passing through the heating coil and the sorbent bank, where the coil is heated, causing release of at least one type of gas species. The outlet dampers, fan and heater are controlled by the electronic control circuit to determine or schedule in which mode the device operates.

In some embodiments, the low vertical profile and the low noise are facilitated by the design of the fan, which is configured to provide uniform air distribution over a low and wide cross section of the system, and deliver sufficient thrust to overcome the resistance of the sorbents, filters and conduits. The use of a plurality of cylindrical impellers on a shared lateral axis is particularly suitable for this purpose.

In some embodiments, an indoor air cleaning apparatus for removing at least a portion of at least one type of gas from an indoor area of a building is disclosed. In some embodiments, the apparatus may comprise a cabinet including a substantially square or rectangular cross section having a height H a width W, and a length L, the cabinet also including at least one inlet, a first outlet, and a second outlet, wherein the cabinet is configured for deployment from an elevated position within an indoor area of a building. Further, the apparatus may include a plurality of dampers for managing airflow through at least one or more of the apparatus, the first outlet and the second outlet; and at least one sorbent bank comprising a plurality of cartridges, wherein each cartridge: comprises a rigid frame, at least a first and a second permeable surface, and one or more sorbent materials contained within the frame, and is configured to receive an airflow through the first permeable surface, over and/or through the sorbent, and expel the airflow through the second surface.

In addition, in some embodiments, the apparatus may have a fan assembly comprising a panel including at least one panel opening, at least one housing including at least one housing inlet and at least one housing outlet, at least one motor and a plurality of parallel, forward curved cylindrical impellers. In some embodiments, the panel may be configured to substantially cover a cross section of the cabinet perpendicular to an airflow direction of the fan assembly; the plurality of parallel, forward curved cylindrical impellers may be arranged on a common impeller axis oriented in a direction parallel to the panel; the fan motor may be located between two impellers; the at least one housing may be attached to the panel such that the at least one housing outlet substantially corresponds to the at least one panel opening so as to allow an airflow exiting the impellers to flow therethrough; and the panel opening may be configured to direct airflow from the housing toward at least the sorbent bank.

In some embodiments, the apparatus may also include a heating element configured to be in one of at least two modes: an active mode whereby an airflow passing over the heating element is heated, and an inactive mode whereby an airflow passing over the heating element is not heated. The apparatus may also comprise a controller configured to operate in at least two modes: an adsorption mode and a regeneration mode, and configured to control at least the plurality of dampers, fan assembly and heating element. In some embodiments, in the adsorption mode, the impeller may draw an indoor airflow from the indoor area, the indoor air entering the inlet of the cabinet then the inlet of the housing, whereby the indoor airflow is optionally directed over the heating element in inactive mode and into the sorbent bank such that at least a portion of at least one type of gas contained in the airflow is captured by the sorbent, the indoor airflow then exiting the cabinet via the first outlet of the cabinet. In some embodiments, in the regeneration mode, the impeller may draw an indoor airflow from the indoor area, the indoor air entering the inlet of the cabinet then the inlet of the housing, whereby the indoor airflow is directed over the heating element in active mode and thereafter the heated indoor airflow is directed to flow over the sorbent such that at least a portion of the at least one type of gas captured by the sorbent during the adsorption mode is released therefrom, then out the second outlet of the cabinet. In some embodiments, the controller can control the plurality of dampers, fan assembly and heating element based upon at least one of a schedule and a concentration level of the at least one type of gas in the indoor airflow.

In some embodiments, the deployment of the cabinet may comprise hanging the apparatus from at least one of a ceiling and a wall of the indoor area. In some embodiments, the apparatus may further comprise a filter configured for removing particulate matter from the air stream, wherein the filter is arranged to filter an airflow prior to or after being received by the sorbent bank. In some embodiments, the filter may comprise a plurality of cyclonic separators.

In some embodiments, the panel is arranged at an oblique angle relative to the height direction of the cabinet between about 5 and about 30 degrees. In yet some embodiments, the panel may be arranged at an oblique angle relative to the height direction between about 2 and about 45 degrees; about 3 and about 40 degrees; about 7 and about 25 degrees; about 10 and about 20 degrees, including values and subranges therebetween.

In some embodiments, the at least one gas type is selected from the group consisting of: carbon dioxide, formaldehyde, acetaldehyde, volatile organic compounds, sulfur oxide, nitrous oxide, hydrogen sulfide, carbon monoxide, and ozone.

In some embodiments, the apparatus may include a conduit in fluid communication with the second outlet, wherein the conduit is configured to carry the airflow expelled by the second outlet away from the room or outside the building. Further, in some embodiments, the apparatus may include at least one of: one or more appendages, brackets, hooks, ears, holes, bars, tabs, and sockets.

In some embodiments, the sorbent bank may be configured for access such that each of or the plurality of cartridges can removed or replaced, wherein access is via at least one of an opening and/or a removable or movable access panel. In some embodiments, at least two of the cartridges are arranged substantially parallel to each other and to the overall airflow direction.

In some embodiments, an indoor air cleaning method for adsorbing at least one type of gas from an indoor airflow without the use of an independent ventilation or circulation system is disclosed. The method may comprise the step of deploying one or more of the apparatuses disclosed above from an elevated position within the room and operating the device to remove at least a portion of the at least one type of gas from the indoor air of the room, wherein deploying comprises hanging the one or more apparatus from at least one of the ceiling or a wall of the room. In some embodiments, the step of deploying the one or more apparatuses may comprise placing the one or more apparatuses within a drop ceiling such that, the one or more apparatuses are configured to receive indoor air from the room via a first grill or first opening in the drop ceiling, and returns air to the room via a second grill or second opening in the drop ceiling.

In some embodiments, an indoor air cleaning apparatus for removing at least a portion of at least one type of gas from an indoor airflow is disclosed. In some embodiments, the apparatus may comprise a cabinet including a substantially square or rectangular cross section, a first outlet, and a second outlet, wherein the cabinet is configured for hanging from an elevated position within an indoor area of a building; at least one sorbent bank comprising at least one cartridge, wherein the at least one cartridge includes one or more sorbent materials; a fan assembly comprising at least one housing including at least one housing inlet and at least one housing outlet, at least one motor and at least one impeller, wherein the at least one housing is arranged within the cabinet such that the at least one housing outlet directs an airflow to the sorbent bank; a heating element configured to operate in at least one of two modes: an active mode whereby an airflow passing over the heating element is heated, and an inactive mode whereby an airflow passing over the heating element is not heated or the airflow is re-directed so as to not flow over the heating element; and a controller configured to operate in at least two modes: an adsorption mode and a regeneration mode, and configured to control at least the fan assembly and the heating element.

In some embodiments, in the adsorption mode, the impeller draws an indoor airflow from the indoor area, the indoor air entering the inlet of the housing, the housing directing the indoor airflow optionally over the heating element in inactive mode, the airflow then being received into at least the sorbent bank such that at least a portion of one type of gas is captured by the sorbent, the indoor airflow then exiting the cabinet via the first outlet of the cabinet. In some embodiments, in the regeneration mode, the impeller draws an indoor airflow from the indoor area by entering the inlet of the housing, the housing directing the indoor airflow over the heating element in active mode and thereafter the heated indoor airflow is directed to flow over the sorbent such that the at least a portion of the one type of gas captured by the sorbent is released therefrom, then out the second outlet of the cabinet. In some embodiments, the controller may control at least the fan assembly and heating element based upon at least one of a schedule and a concentration level of the at least one type of gas in the indoor airflow.

In some embodiments, the device may be further configured with a particle filter before or after the sorbent bank. The particle filter may comprise any suitable filter or alternatively, an array of cyclonic separators, offering less frequent need for replacement or maintenance.

DETAILED DESCRIPTION OF SOME OF THE EMBODIMENTS

In order to scrub indoor air in a room without relying on central ventilation or circulation, a scrubber is designed for placement in or above the room. In some embodiments, the scrubber is placed over the ceiling or just below the ceiling, thereby minimizing its physical or visual imposition. The scrubber can be supported in its place by attaching it to the ceiling or to the walls. In some embodiments, the scrubber may be further designed for a horizontal configuration with minimum vertical profile.

FIGS. 1A and 1B, are each a schematic illustration of the scrubber10, according to an embodiment of the present disclosure. The scrubber10comprises a sealed box or cabinet100(FIG. 1A), typically a rectangular one with a length (L), width (W) and a height (H). These directions are referred to as longitudinal, lateral and vertical, respectively. The air flows along the length of the cabinet, namely longitudinally, which ordinarily would be parallel to the ceiling and floor.FIG. 1Bshows the same scrubber10with the longitudinal side panel102and the inlet side panel or grille104removed. As shown inFIG. 1B, the scrubber10further comprises a fan110, an inlet120, and a first outlet130to direct clean air back to the room, and a second outlet140for regeneration exhaust. In certain embodiments the inlet120is simply a rectangular or circular opening on the incoming side of the cabinet, which may be protected with a grille104or a screen. Other shapes of the inlet120may be used for aesthetic or functional purposes. In other embodiments, the opening can have a flange or a short rectangular or circular sleeve which can facilitate attachment of an air duct.

The scrubber10further comprises a sorbent bank150comprising sorbent sheets or cartridges170, and a heater152which may comprise a heating element such as a heating coil or any other suitable heating means. The first and second outlets130and140may be separately governed by corresponding first damper154and second damper155or shutters that are equipped with a controller156including actuators and activated by a control circuit. The inlet120generally does not require a damper but may have one. The outlets130and140may further comprise a circular or rectangular flange, or a sleeve, to facilitate connection to an air duct.

The room or space may be located in an enclosed environment which may include a building, an office building, a commercial building, a bank, a residential building, a house, a school, a factory, a hospital, a store, a mall, an indoor entertainment venue, a storage facility, a laboratory, a vehicle, an aircraft, a ship, a bus, a theatre, a partially and/or fully enclosed arena, an education facility, a library and/or other partially and/or fully enclosed structure and/or facility which can be at times occupied by equipment, materials, live occupants (e.g., humans, animals, synthetic organisms, etc.) and/or any combination thereof.

In some embodiments, some or all of the cabinet walls158may be further configured with thermal and/or acoustic insulation, to minimize heat from the heater152, and noise from the fan110, escaping to the room. The cabinet walls158may be formed of a thermal and/or acoustic insulation material. Additionally or alternatively a thermal and/or acoustic insulation layer may line the cabinet walls158.

FIGS. 2A and 2Bare each a schematic illustration of the deployment of the ceiling-mounted scrubber10, according to an embodiment of the present disclosure. InFIG. 2Athe scrubber10is configured for deployment from an elevated position within an indoor area of a building and may be attached to the ceiling directly, secured by bolts, screws or any other suitable attachment. Alternatively, it can be hanging from the ceiling or wall with the help of supporting brackets, rods, cables, straps, appendages, hooks, ears, bolts, holes, bars, tabs, sockets or other suitable structures. The inlet120and the first outlet130are open to the room either directly or via an open ended duct160that extends towards the room. The end of these ducts may comprise a diffuser or a grille162. In some embodiments, common in commercial buildings, there is a drop ceiling, also known as a tiled ceiling, false ceiling or acoustic ceiling. The scrubber10can be supported above the drop ceiling and connected to the grille162or an opening in the drop ceiling via a short duct segment, as shown inFIG. 2B. A separate grille may be configured for the inlet120and the first outlet130or second outlet140.

In some embodiments, it is advantageous to have a low vertical profile, namely minimize the height (H), of the scrubber10. For example, if the scrubber is hanging below the ceiling, it must not take up too much head room. Alternatively, if it is positioned above the drop ceiling, the amount of vertical space available above the drop ceiling may be very limited. Therefore, designing the scrubber10with a low vertical profile can be an important feature or consideration. In some embodiments, the scrubber height may be less than about 20 cm. In some embodiments the scrubber height may be less than about 30 cm. In some embodiments the scrubber height may be less than 50 cm. These unique requirements have implications for the design and selection of the key components of the scrubber10, including the sorbent bank150and the fan110.

When the fan110is turned on, air is drawn from the indoor space or room via the inlet120and forced to flow through the sorbent bank150and through the first outlet130, back to the space or the room. As the air flows through the bank150, it briefly passes through or along the sorbents in the bank150, where contaminant molecules are adsorbed and captured before the air proceeds to flow towards the first outlet130. As a result, air with reduced level of these contaminants is returned to the room. Due in part to the motion of air in the room caused by this action, also shown schematically inFIGS. 2A and 2B, the air in the room is mixed and continually cleaned by the scrubber10. Thus the performance of the scrubber is not dependent on other means of circulation or mixing of the air.

The types of gas species comprising contaminants removed by this action depend in part on the choice of the sorbent material. Various sorbents capture many types of indoor molecular contaminants, including but not limited to acidic gases, carbon dioxide, volatile organic compounds, organic gases like formaldehyde, acetaldehyde and methane, as well as inorganic gases such as ozone, nitrous oxides, sulfur oxides, carbon monoxide, hydrogen sulfide, radon and many others.

Sorbents may include molecular sieves, zeolite, natural and synthetic activated carbon, silica, synthetic silica, alumina, polymers, fibers, amines, metal-organic frameworks, clays and various sorbents formed by impregnating or coating high surface area materials, for example. In an embodiment a liquid amine or amine polymer is supported on a high surface area inorganic material like silica, alumina, clay or zeolite. The sorbent may comprise solid supported amines or any other adsorbent material, in any suitable form, such as porous granular solids or pelleted shaped solids, for example. In some embodiments, combinations, mixtures, or blends of different materials can provide superior air cleaning adsorption performance.

The sorbents may lose their adsorptive efficiency as they become saturated with adsorbate molecules of the gas species. This is where regeneration of the sorbent becomes significant. Temperature swing adsorption (TSA) is a technique where a sorbent is repeatedly cycled between adsorption and regeneration. During adsorption the sorbent is kept at neutral temperature (i.e. room temperature) or even cooled, whereas during regeneration it is heated. During adsorption various molecular species are captured by the sorbent, settling on its surface through physisorption or chemisorption, thereby removing the molecular gas species from the air stream. On the other hand, during regeneration, the elevated temperature of the sorbent causes at least a portion of the captured molecular gas species to be released into the airstream, which in turn can be exhausted to the appropriate second outlet140. After regeneration the sorbent is cooled and then able to resume its scrubbing action. This TSA cycle can be repeated many times, allowing long term use of the sorbent.

A feature of the scrubber10is its ability to perform automated, in-situ regeneration. This is enabled by a combination of a heater152, a separate exhaust outlet140, and a control circuit of the controller156that manages the heater152and the air flow path by means of fans110, dampers154and155, and their respective actuators. During regeneration, the coil of the heater152may be heated with electric power, and as air passes over the heater152and towards the sorbent bank150, the sorbent itself is heated. The heated sorbent gradually releases the captured contaminants. After a sufficient amount of the contaminants are thus released, the sorbent is allowed to cool down and then resume its air cleaning operation.

The heater152is configured to be in an active mode whereby the airflow passing over the heater152is heated, and in an inactive mode whereby the airflow passing over the heater152is not heated.

Some sorbents are better suited for regeneration than others, especially with regard to an ability to regenerate more easily, such as without requiring excessively high temperatures, which would not be practical in a compact indoor air scrubber10. For example, sorbent comprising solid-supported amine polymers provide for good adsorption of carbon dioxide and other gas species at room temperature with relatively low heat regeneration, as low as 60° C., 50° C. or even below 50° C. The regeneration may be performed at any suitable temperature, such as between about 20-200° C. and subranges thereof or at about 40-80° C. and subranges thereof.

The digital electronic circuit, namely the controller156, governs the operating mode of the scrubber10, including fan operation, damper positions, adsorption and regeneration. It also directs power to the fan110and in some embodiments, the fan110may be operated at different speeds. The control circuit of the controller156can control the fan speed by changing the voltage on the fan110or by driving the fan110with pulse width modulation. Different air flow speeds may be required for different conditions, for example, higher flow when more air cleaning is required, and lower air flow for less fan noise and less power usage. Optimal air flow for regeneration may also be different than the airflow during adsorption, and even during the regeneration process different rates of air flow during the different stages of regeneration may be required.

For example, in some embodiments, air speed is reduced during the part of the regeneration to allow the air to reach higher temperature and longer dwell time with the sorbent to maximize heat transfer to the sorbent. Air flow rate can be reduced by as much as 50%-80% to optimize heating rate. Once the sorbent achieves its target temperature, more airflow can be advantageous to accelerate the removal of the contaminates and the eventual cool down of the sorbent. The control circuit of the controller156further has the ability to direct power to the heating coil when needed for regeneration.

FIGS. 3A and 3Bare each a schematic illustration of two configurations of the regeneration exhaust conduit, according to an embodiment of the present disclosure. For the ceiling-mounted scrubber10described herein, it is necessary to provide an appropriate and practical means of exhaust for the air stream during regeneration.FIGS. 3A and 3Bdepict how this is done by means of a small hose, duct or flexible outlet conduit160that extends from the exhaust outlet140to an appropriate outlet from the building. In some embodiments the exhaust outlet140may comprise a thermal insulation material and/or thermal insulating layer, to minimize heat exchange between the exhaust and the indoor space.

In one embodiment, shown inFIG. 3A, the second outlet140is connected to the exhaust of a nearby bathroom. Bathrooms in most public buildings, as well as in many residential homes, are routinely configured with an exhaust to provide ventilation. In some embodiments, the scrubber outlet conduit160can extend discreetly over the drop ceiling to the nearby bathroom where it can be attached to the exiting bathroom exhaust pathway.

In another embodiment, shown inFIG. 3B, the outlet conduit160extends to a nearby window or opening in the outside wall of the building, allowing the exhaust to be purged directly outside during regeneration.

Any other suitable outlet configuration can be utilized. These can include built-in smoke stacks, chimneys, elevator shafts, kitchen exhausts or any other suitable path that allows the purge air to flow outside the building. In one embodiment (not shown) the scrubber is adjacent to a window, allowing direct exhaust through the window.

FIGS. 4A and 4Bshow a side view of the multi-sheet sorbent bank configuration, according to an embodiment of the present disclosure.

In order to increase the amount of air flowing through the sorbent and/or to reduce the flow resistance, multiple sheets, also referred to as cartridges170, can be configured in a parallel or non-parallel geometry. One such parallel geometry is shown inFIG. 4A. In this embodiment, the sorbent bank150comprises six sheets170(or any other suitable number of sheets170) that are placed in parallel to each other and to the air stream, with intermittent blockages174, such that air is forced to flow through one of the sheets in order to get across the bank150in the direction of the air flow, illustrated by the arrows. The sheets in this configuration are typically flat and rectangular but may have other designs. In another embodiment the sheets are tilted relative to the floor of the cabinet100and to their neighboring sheets to form a zig-zag or V-bank patterns, as shown inFIG. 4B.

Each or some of the sorbent sheets or cartridges170can be constructed from a rigid frame175(FIG. 1B) that supports the sorbent material between two permeable surfaces176and178, as disclosed in applicant's PCT application PCT/US2015/015690, which is incorporated herein by reference in its entirety. The cartridge170is configured to to receive an airflow through the first permeable surface176, over and/or through the sorbent, and expel the airflow through the second permeable surface178. The cartridge170can be divided into compartments or a honeycomb structure or any other structure to better support a granular sorbent material.

In some embodiments, each of the sorbent cartridges in the bank150can be removable and replaceable. This can be a desirable feature as many sorbents tend to age and lose efficacy over time (e.g. a few months or years), even with the TSA cycle. Thus periodically the sorbent cartridges170can be replaced with new cartridges and fresh sorbent. To this end the scrubber10may be formed with a removable or movable access panel102(FIG. 1A) that can be opened, allowing access to the sorbent sheets170which in turn can be pulled out, with new sheets inserted in their place. The panel102can be hinged or entirely removable.

In other embodiments, the sorbent bank150can have non-planar cartridges each comprising a single monolithic structure such as a V-bank, one or more hollow cylinders, or any other suitable form designed to enable air to flow through the sorbent material.

FIGS. 5A, 5B, 5C, 5D, 5E and 5Feach show elements of an embodiment of a fan assembly110, according to an embodiment of the present disclosure.

In some embodiments, the fan design is an important consideration in the design of the entire system. The fan110(also referred to as the fan assembly110) may be designed to be as quiet as possible, because the scrubber10operates in close proximity to people who are working or living in the room or space. It further may deliver a uniform air stream through the low-profile rectangular cross section of the scrubber10, which is dictated by the ceiling-mount design and the cartridge bank design. Finally, the fan110may produce sufficient thrust or static pressure to effectively drive the air stream though the dense sorbent bed, as well as the particle filters (220inFIG. 7A) and any other air treatment components along the flow path of the air.

In one embodiment, the fan110can be implemented in the form of multiple cylindrical impellers190attached to a common horizontal axis192that is oriented in the lateral direction, namely along the width (W) of the cabinet100, perpendicular to the longitudinal direction of the air flow. This two-impeller190configuration is shown schematically inFIGS. 5A-5C. In a non-limiting example the two-impeller190configuration is comprises two cylindrical impellers, each with a 10 centimeter diameter. The lateral-axis, multi-impeller fan is beneficial in providing air flow that is evenly distributed along the entire cross section of the cabinet. In contrast, a fan110turning on a longitudinal axis would be limited by the vertical profile of the cabinet. In some embodiments additional impellers may be arranged along axis192.FIG. 5Dillustrates four impellers on a shared axis192, and5E illustrates the corresponding assembly with a housing194and a panel210andFIG. 5Fshows the four impeller design with the motor in the middle.

A cylindrical impeller190draws in air along the flat ends, or bases, of the cylinder, so a single long cylinder would draw in air mostly along the edges of the rectangular cross section of the cabinet100, in contrast, having two or four or more separate cylindrical impellers190on the same axis presents a more even distribution for drawing air along the entire cross section while also pushing air forward through the entire cross section. The shared axis192is not only geometrically suitable but also allows a single motor194to drive all the impellers190through one common axis.

The multi-impeller fan is enclosed by a housing196with a plurality of openings at housing inlet204along the cylindrical bases for drawing air, and a plurality of openings at housing outlet206located on a flat front attached to a panel210, which is configured with matching openings or windows through which the air flows out. The housing196is attached to the panel210that fits into a cross section of the scrubber cabinet, as shown inFIG. 1B. The panel210, the housing196, the motor194and the impellers190are referred to as the fan assembly110. The fan assembly110can be positioned before or after the sorbent bank150and the heater152. There is an advantage in placing the fan before, or “upstream” of, the heater152and the bank150so that the fan110itself is not exposed to the heated air, for example if the heat is detrimental to the fan motor or other fan components.

In some embodiments, a critical feature of the fan is quiet operation, specifically its ability to deliver the required thrust with minimal noise. Quiet performance of an indoor air scrubber is important for minimal disruption to the occupants, as explained above. While other fan designs can be used to provide required air flow, the multiple cylindrical impellers deliver the required flow, thrust and distribution with lower speeds and therefore lower noise, especially with forward curved blades. In some embodiments, noise of less than about 45 dB, or less than about 50 dB is required. Tests show that a dual-impeller fan with two, 10 centimeter diameter, cylindrical forward curved impellers, delivered 150 CFM with a noise level of approximately 35 dB and sufficient thrust to deliver static pressure of 500 Pascal.

In one embodiment, a single motor, dual centrifugal forward curved impeller fan in horizontal housing configuration is used.FIGS. 5A-5Cshow such a fan. The fan110is attached to a cross-sectional panel that is attached to the inner walls of the cabinet100. The fan utilizes two cylindrical impellers with 10 centimeter (cm) diameter and 10 cm length each, with a gap of about 10 cm between the two impellers, for a total assembly length of approximately 30 cm. Turning toFIGS. 5D, 5E and 5F, it is shown that in some embodiments, the fan assembly110may be configured with two impellers190at each side of the horizontal axis192. A plurality of impellers190may be arranged on the axis192.

This wide form, dual fan configuration, shown inFIGS. 5A-5F, provides a good horizontal distribution of the air flow with the low vertical profile, allowing optimal utilization of the horizontal sorbent sheets170and generally making best use of the rectangular cross section of the scrubber10. Furthermore, the forward impellers190deliver the required air flow with lower noise than axial fans or conventional impeller fans.

FIG. 6shows a side view of the fan assembly110inside the cabinet100with the supporting panel210tilted relative to the vertical orientation to improve air distribution among the sorbent sheets170, according to an embodiment of the present disclosure. As seen inFIG. 6, in some embodiments, air flow among the sheets170is another important consideration in the design. The lateral-axis multiple impeller fan design generally provides a wide rectangular flow and pressure front. However, the air emerges from the fan housing196tangentially, which in the assembly configuration shown is on the upper side of the fan panel. In a low-profile cabinet, this would result in more air flow through the upper sheets of the sorbent bank, therefore underutilizing the lower sheets. The uneven air distribution can be corrected with a small tilt in the fan as shown inFIG. 6. In one embodiment, the panel210is arranged at an oblique angle relative to the height direction H of the cabinet100and the tilt is approximately 10 degrees. In other embodiments the tilt is between about 5 degrees to 30 degrees and values and subranges thereof. In some embodiments the tilt can be between about 2 degrees and 45 degrees and values subranges thereof.

In some embodiments, the scrubber10is deployed as a multi-pass scrubber, namely the same air volume passes many times through the scrubber10in a given period of time. The clean, scrubbed air is returned via the first outlet130into the room. The room air thereafter enters the scrubber via inlet120. As a result, complete cleaning of the air during a single pass is neither necessary nor even optimal, but rather the cumulative cleaning effect of multiple passes is the functional objective and a criterion for design.

FIGS. 7A and 7Beach show a low profile scrubber with a pre-filter assembly, according to an embodiment of the present disclosure.

As shown inFIGS. 7A and 7B, in some embodiments, in addition to the sorbent bank150, other air treatment components can be introduced before or after the bank150in the flow path of the air. A particulate filter220can be introduced between the first inlet120and the fan110, to capture dust and other solid particulates and prevent them from building up on the fan110, the heater152and the sorbent bank150, or from circulating back in the room air. Similarly, particulate filters can be configured downstream, after the sorbent bank150, to prevent the particulate from circulating back into the room.

The removal of particulate matter (PM), including the dust and other solid particulates, from the air stream is an important benefit in environments with high PM pollution. The removal of PM from an airstream is conventionally performed by any of a wide variety of air cleaning components such as media filters, where air flows through a permeable medium like paper or fabric, and particles are captured by the fibers. However, such filters tend to have short operating life as they become clogged with the captured solids, and therefore require frequent replacement. Frequent replacement of filter media in an indoor scrubber, and especially a hard-to-reach ceiling-mounted scrubber, can be disruptive and onerous to the people working or living in the space or room. Electrostatic precipitators are may be used as a mechanism to capture PM, but these too require frequent maintenance and cleaning which can be disruptive and onerous.

In some embodiments, cyclonic separation of the PM from the air stream can provide a low-maintenance alternative to replaceable filters. The cyclonic separation can be implemented by passive monolithic arrays of small cyclonic separators as disclosed in applicant's PCT application PCT/US2016/043922, which is incorporated herein by reference in its entirety. These arrays provide an effective removal of PM with very long operating life, without being replaced or cleaned.FIG. 7Ashows the particulate filter220comprising a cyclonic array subassembly configured at the inlet side of the scrubber10, before the fan110. In this embodiment the cyclonic separator subassembly220comprises a plurality of monolithic arrays222that can be organized as parallel horizontal layers. Other configurations are also possible, including single layer or a vertically arranged array. The cyclonic separator subassembly220is supported inside the cabinet with rails, tracks, tabs or posts that hold the cyclonic separator subassembly220in place. The cyclonic separator subassembly220can nevertheless be removed and replaced if necessary by opening the side panel and sliding it out. In some embodiments, the location of the cyclonic sub assembly220can be between the fan110and the sorbent bed150or after the sorbent bed150. In some embodiments the cyclonic array subassembly220can be a separate module that is outside the main cabinet100, attached to the inlet or outlet of the scrubber, as shown inFIG. 7B, for example.

Other air cleaning components, besides the particulate filters and the cyclonic separator subassembly, that may be incorporated include, but are not limited to, ultraviolet sources, ionizers, electrostatic precipitators, catalysts, antimicrobial materials, deodorizers, and other media filters. In some embodiments, a carbon fiber layer may be used to remove certain odors or contaminants from the air.

FIG. 8shows a scrubber where the exhaust outlet is located on the cabinet between the sorbent bank and a subsequent air cleaning component, according to an embodiment of the present disclosure. As shown inFIG. 8, in some embodiments, the regeneration exhaust outlet140can be configured to remove the exhaust air before it reaches these additional air cleaning component. In this configuration there would be a “dead” space226between the sorbent bank150and additional downstream air cleaning components, an exhaust outlet140, and the exhaust outlet140would draw air from this space. The exhaust outlet140can be then located on the side, the bottom or the top of the cabinet adjacent to this space, as shown inFIG. 8. By locating the exhaust outlet140upstream from these air cleaning components, the warm exhaust air does not flow through these air cleaning components, thus minimizing their unintentional heating and also preventing the exhausted contaminants from reaching these air cleaning components.

In a non-limiting exemplary scrubber10, such as shown inFIGS. 1A and 1B, a lateral-axis dual impeller fan is used to deliver a flow rate of 150 CFM through a six-sheet cartridge bank. Each sheet is a 400×450 mm rectangle that is 20 mm thick. If placed over a room with a floor area of 500 square feet and 9-foot ceiling height, namely a volume of 4500 cubic feet, the scrubber treats an amount of air equivalent to the entire room volume every 30 minutes. As long as sorbents capture a percentage of the contaminants that is equivalent or higher than the amount introduced into the room during that time, their concentration in the air will be continually maintained or reduced.

In some embodiments the scrubber10may be attached to a wall or a window rather than the ceiling. If the scrubber is attached to a window or external wall, the exhaust outlet could be directly open to the outside, eliminating the need for an exhaust duct.

The electronic circuits of the controller156that control the scrubber determine whether the fan110is on, and in the case of a variable speed fan, they can control the fan speed via voltage, amplitude or pulse width modulation. They further control which dampers are open and how much power is delivered to the heater152at any time. Software implemented algorithms can determine when and how long the system undergoes regeneration. Alternatively, regeneration can be scheduled manually by a user or communicated to the control circuit of the controller156by an external digital signal or a portable device including but not limited to a smart phone, a remote controller or a portable computer. The communication can be wired or wireless and use any suitable technology, network and protocol, including but not limited to infrared, WiFi, Bluetooth®, LoRa®, or any suitable technology or standard.

The scrubber10may comprise various sensors230(FIG. 1B) for detecting air quality metrics. Such sensors may include carbon dioxide, carbon monoxide, oxygen, formaldehyde, TVOC (total volatile organic compounds), temperature, humidity, and particulate sensors such as PM2.5, PM10, PM1.0, or any other air quality sensor. The sensors230may be configured to measure the concentration level of the type of gas of the gas species in the indoor airflow. The control circuits can receive the readings from these sensors230. The readings can be stored or communicated to other devices. The sensor readings can also be used to determine the optimal fan speed or whether to start a regeneration cycle, and for how long. In some embodiments, the sensor230may be positioned out of the scrubber10at a suitable location within the room and/or out of the room.

In some embodiments, the operation of the scrubber10may include an adsorption mode and a regeneration mode. The controller156is configured to operate the adsorption mode and the regeneration mode and control the first and second outlet dampers154and155, fan110and heater152.

During the adsorption mode, the impellers190draw indoor airflow from the indoor area. The indoor air enters the inlet120of the cabinet100and then the inlet of the housing196of the fan assembly110. The indoor airflow is optionally directed over the heater152in an inactive mode and into the sorbent bank150such that at least a portion of the gas species contained in the airflow is captured by the sorbent. The indoor airflow then exits the cabinet100via the first outlet130of the cabinet100.

During the regeneration mode, the impeller190draws an indoor airflow from the indoor area. The indoor air enters the inlet120of the cabinet100and then the inlet204of the housing196of the fan assembly110. The indoor airflow is directed over the heater152in the active mode and thereafter the heated indoor airflow is directed to flow over the sorbent such that at least a portion of the gas species, captured by the sorbent during the adsorption mode, is released therefrom and then out the second outlet140of the cabinet100.

The controller156controls the first and second outlet dampers154and155, fan110and heater152based upon at least one of a schedule (i.e. in which mode, e.g. adsorption or regeneration, the scrubber operates) and a concentration level of the type of gas in the indoor airflow.

FIG. 9shows an indoor air gas adsorption system250comprising a plurality of scrubbers10in communication with a console252, by digital communication or any other suitable means, according to an embodiment of the present disclosure. The console252may comprise one or more of air quality sensors230, and digital electronics254, display256, and communications circuitry258. The console252can send a signal to turn on and off the individual scrubbers10. It may do so based on sensor readings, scheduling, external signals received by the console252, or any other algorithm that is implemented within the console252or within another computer that communicates with the console252. The console252can also communicate with other digital systems that directly or indirectly control the building's HVAC, like a Building Management System.

In some embodiments, the scrubber10may comprise a first inlet and a second inlet. In some embodiments the first inlet may be configured for introducing indoor air into the scrubber10for contaminate removal thereof and the second inlet may be for introducing indoor or outdoor air into the scrubber for regeneration of the scrubber.

While various inventive embodiments have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and/or structures for performing the function and/or obtaining the results and/or one or more of the advantages described herein, and each of such variations and/or modifications is deemed to be within the scope of the inventive embodiments described herein. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be an example and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the inventive teachings is/are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific inventive embodiments described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, inventive embodiments may be practiced otherwise than as specifically described and claimed. Inventive embodiments of the present disclosure are directed to each individual feature, system, article, material, kit, and/or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, and/or methods, if such features, systems, articles, materials, kits, and/or methods are not mutually inconsistent, is included within the inventive scope of the present disclosure. Some embodiments may be distinguishable from the prior art for specifically lacking one or more features/elements/functionality (i.e., claims directed to such embodiments may include negative limitations).

Any and all references to publications or other documents, including but not limited to, patents, patent applications, articles, webpages, books, etc., presented anywhere in the present application, are herein incorporated by reference in their entirety. Moreover, all definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and/or ordinary meanings of the defined terms.