WO2025075692A1

WO2025075692A1 - Systems, assemblies, and methods associated with an air separation module having an integrated ozone converter

Info

Publication number: WO2025075692A1
Application number: PCT/US2024/037721
Authority: WO
Inventors: Brian A. AULT; Kristopher J. ELLIOTT; Robert W. RATHFELDER; Omar S. ALQUADDOOMI
Original assignee: Parker Hannifin Corp
Current assignee: Parker Hannifin Corp
Priority date: 2023-10-04
Filing date: 2024-07-12
Publication date: 2025-04-10
Anticipated expiration: 2026-04-04

Abstract

An example air separation module includes: a housing; an inlet endcap coupled to the housing and having an inlet port for receiving air flow; an ozone converter disk disposed within the inlet endcap, wherein the ozone converter disk has an open cell structure that allows air to be diffused in radial and axial directions such that air follows a tortuous path as air traverses the ozone converter disk, and wherein the ozone converter disk includes a catalyst that converts ozone in the air into another substance; a bundle of a plurality of hollow fibers disposed within the housing, wherein the bundle receives air from the ozone converter disk and separates air into an oxygen-rich portion and a nitrogen-rich portion; a discharge port through which the oxygen-rich portion is discharged to an external environment; and an outlet port through which the nitrogen-rich portion is provided to a fuel tank.

Description

Systems, Assemblies, and Methods associated with an Air Separation Module Having an Integrated Ozone Converter

CROSS REFERENCE TO RELATED APPLICATION

[0001] The present application claims priority to U.S. Provisional Patent Application No. 63/587,915, filed on October 4, 2023, the entire contents of which are herein incorporated by reference as if fully set forth in this description.

TECHNICAL FIELD

[0002] This disclosure relates to an air separation module (ASM) with an integrated ozone converter. More particularly, the disclosed ASM-integral ozone converter is configured to achieve an ultra-high ozone conversion efficiency (e.g., 99 ,7%-99.95%) over a wide range of ASM operating conditions.

BACKGROUND

[0003] Aircraft fuel tank inerting systems typically include one or more Air Separation Modules (ASMs) that produce inert gas to create/maintain a non-flammable environment within the aircraft fuel tank ullage. In such systems, the ASMs are fed with air that is initially drawn from the local atmosphere by the aircraft engines, then compressed, conditioned, and ultimately routed to each ASM inlet. The ASMs then separate atmospheric air into its primary components, typically nitrogen and oxygen.

[0004] Some ASMs have hollow polymeric fiber membranes that perform the separation. The air processed by the ASMs includes ozone, which is destructive to the polymeric fiber membranes within an ASM. As such, ASM-based inerting systems typically include one or more ozone converters configured to reduce the ozone concentration of the ASM feed air to levels that are less destructive to the ASM. For example, such ozone converters can be configured to convert ozone to oxygen.

[0005] Conventional ozone converters typically operate at high temperature to reduce ozone concentrations to acceptable levels. Particularly, in such conventional ozone converters, ozone conversion is achieved only at higher temperatures and long residence times. For that reason, these conventional ozone converters are typically located near the bleed ports, making use of the high bleed air temperature of about 350 °F. After ozone breakdown, the treated air is cooled prior to entering the ASM, which typically operates at a temperature far lower than the bleed air temperature to achieve a good balance of ASM performance and durability.

[0006] To ensure long ASM service life, it may be desirable to reduce the ozone concentration of the feed air to no more than 1 part per billion by volume (ppbv) before it enters the hollow fiber membranes within the ASM. This can be a challenging task, considering that the ozone concentration of ambient air can range from about 50 ppbv at sea level to several hundred ppbv at high altitude, even exceeding 1,000 ppbv at high altitude and high latitude conditions.

[0007] To achieve such target reduction in ozone concentration, it may be desirable to have an ozone converter with an ultra-high efficiency (e.g., having the ability to convert 99.7% - 99.95% of the ambient ozone). Existing ozone converters, however, are incapable of achieving such high efficiency. In particular, there is no single device in current aircraft inerting systems that achieves such high level of ozone conversion. Rather, either multiple devices are included in the system, which increases weight and cost, or a single device with lower conversion efficiency is used, and the potential negative effects on ASM service life of such low efficiency (e.g., periodic service, replacement, etc.) are accepted.

[0008] Further, conventional ozone converters placed near high temperature zones disadvantageously require periodic maintenance due to the accumulation of contaminants, e.g., lubricants and volatile organic compounds (VOC), from the bleed air stream on the catalyst surfaces. Existing filters cannot protect such conventional ozone converters, as filters do not tolerate high temperature, and are thus typically located downstream from a heat exchanger, which is in turn disposed downstream from the ozone converter.

[0009] It may thus be desirable to have a compact ozone conversion device that integrates directly into an ASM (at a low temperature location) and achieves ultra-high ozone conversion efficiency (e.g., 99.7% - 99.9% or better when new) across a wide range of operating conditions. It is with respect to these and other considerations that the disclosure made herein is presented.

SUMMARY

[0010] The present disclosure describes implementations that relate to systems, assemblies, and methods associated with an air separation module having an integrated ozone converter.

[0011] In a first example implementation, this disclosure describes an air separation module including: a housing; an inlet endcap coupled to the housing and having an inlet port for receiving air flow; an ozone converter disk disposed within the inlet endcap, wherein the ozone converter disk has an open cell structure that allows air to be diffused in radial and axial directions such that air follows a tortuous path as air traverses the ozone converter disk, and wherein the ozone converter disk includes a catalyst that converts ozone in the air into another substance; a bundle of a plurality of hollow fibers disposed within the housing, wherein the bundle receives air from the ozone converter disk and separates air into an oxygen-rich portion and a nitrogen-rich portion; a discharge port through which the oxygen-rich portion is discharged to an external environment; and an outlet port through which the nitrogen-rich portion is provided downstream to a fuel tank of an aircraft.

[0012] In a second example implementation, this disclosure describes an inerting system including: a heat exchanger configured to receive air bled from an engine of an aircraft and cool the air; a filter disposed downstream of the heat exchanger and configured to remove particulates and aerosols from the air; and the air separation module of the first example implementation disposed downstream from the filter.

[0013] The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, implementations, and features described above, further aspects, implementations, and features will become apparent by reference to the figures and the following detailed description. BRIEF DESCRIPTION OF THE FIGURES

[0014] The novel features believed characteristic of the illustrative examples are set forth in the appended claims. The illustrative examples, however, as well as a preferred mode of use, further objectives and descriptions thereof, will best be understood by reference to the following detailed description of an illustrative example of the present disclosure when read in conjunction with the accompanying Figures.

[0015] Figure 1 illustrates a simplified schematic of an inerting system, according to an example.

[0016] Figure 2 illustrates a simplified schematic of an inerting system having a filter-integral ozone converter, according to an example.

[0017] Figure 3 illustrates a simplified schematic of an inerting system having an ASM with an ozone converter integrated therewith, according to an example implementation.

[0018] Figure 4 illustrates a simplified schematic diagram of a partial cross section of the ASM of Figure 3, according to an example implementation.

[0019] Figure 5 illustrates an enlarged view of a portion of a substrate of an ozone converter disk made of reticulated foam, according to an example implementation.

[0020] Figure 6 illustrates an enlarged view of a portion of a substrate of an ozone converter disk made of felt, according to an example implementation.

[0021] Figure 7 illustrates a simplified schematic of an inerting system having an ASM with an ozone converter integrated therewith and another ozone converter upstream of a heat exchanger, according to an example implementation. [0022] Figure 8 illustrates a simplified schematic of an inerting system having an ASM with an ozone converter integrated therewith and a filter that has an ozone converter integrated therewith, according to an example implementation.

[0023] Figure 9 illustrates a simplified schematic of an inerting system having an ASM with an ozone converter integrated therewith, an ozone converter upstream of a heat exchanger, and a filter that has an ozone converter integrated therewith, according to an example implementation.

DETAILED DESCRIPTION

[0024] Disclosed herein are systems, assemblies, and methods associated with an ASM having an integrated ozone converter that, compared to the ozone converter technologies currently used in aircraft inerting systems, provides enhanced ozone protection for the ASM in a compact, lightweight package, requires no maintenance for the life of the ASM, and employs low-cost materials. As such, the disclosed ASM provides reduced cost, weight, and maintenance advantages for an aircraft operator.

[0025] Within examples, disclosed herein is an inerting system that includes an ASM having an ozone converter integrated therewith in a compact package. Further, the ozone converter integrated into the ASM has an “open cell” configuration that enhances ozone conversion efficiency, and may increase the residence time of air within the ozone converter, thereby further enhancing conversion efficiency. With such enhanced conversion efficiency, the ASM-integral ozone converter can be a stand-alone converter capable of protecting the ASM without supplementation from other ozone converters.

[0026] The term “conversion efficiency” is used generally herein to indicate a ratio of the amount of ozone converted to another substance (or substances), such as oxygen, to the total amount of ozone that enters the ozone converter. The efficiency is expressed as a percentage and is calculated using the following formula:

. .. ... . Amount o f Ozone Converted .

Conversion Efficiency = - x 100

Total Amount of Ozone where the “Amount of Ozone Converted” is the quantity of ozone that undergoes a chemical reaction and is transformed into a different substance, and the “Total Amount of Ozone” is the initial quantity of ozone that enters the ozone converter. [0027] Figure 1 illustrates a simplified schematic of an inerting system 10, according to an example. The inerting system 10 includes an ozone converter 12, a heat exchanger 14, a filter 16, and an ASM 18. Although the schematic in Figure 1 shows only a single ASM, multiple ASMs can be used in parallel depending on the size of the fuel tank and volume of ullage space to be inerted.

[0028] The ASM 18 can include tens of thousands of hollow fiber membranes to produce inert gas, which is then delivered to the fuel tank for flammability reduction. Particularly, the ASM 18 receives air at an inlet port 20, then separates the air stream into an oxygen-rich portion and a nitrogen-rich portion (which is inert). The oxygen-rich portion of the air is discharged through a discharge port 22 to an environment of the aircraft, and the nitrogen-rich portion is provided via an outlet port 24 to the fuel tank.

[0029] As an example, the ASM 18 can reduce the concentration of oxygen from 21% in the air supply to about 12% in the nitrogen-rich portion provided to the fuel tank. Such lower oxygen percentage is sufficient to render the air provided to the fuel tank inert, thereby reducing flammability of the fuel tank ullage.

[0030] The source of air (e.g., compressed air) to the inerting system 10 can be the engine bleed air supply. Particularly, such air is drawn in from the local atmosphere by the aircraft engine and “bled off’ one of the engine compressor stages to be used for various purposes throughout the aircraft (e.g., cabin pressurization and the inerting system 10). To ensure proper operation and service life of the ASM 18, the air being supplied to the ASM 18 is conditioned to achieve a suitable operating temperature and remove various contaminants from the air, which could potentially degrade performance and/or longevity of the ASM 18. [0031] For example, once the bleed air enters the inerting system 10, it is directed through the ozone converter 12, which is configured to convert a significant portion of the ozone in the bleed air into oxygen to prevent subsequent ozone-induced damage to the fibers of the ASM 18.

[0032] The ozone converter 12 can be a self-contained, line-replaceable unit, the purpose of which is to reduce ozone concentration of the air stream fed from the engine to protect the ASM 18. The ozone converter 12 can be configured as a package or assembly having an ozone-reducing ‘core’ disposed in a housing. The housing is generally cylindrical in shape, on the order of 10 to 13 inches long and the assembly weighs from 2 to 4 pounds, for example.

[0033] The core typically uses one or more precious metal ozone catalysts (e g., palladium and/or platinum) impregnated in a so-called ‘washcoat’ layer, which is deposited on a metallic substrate. The substrate is typically constructed of rigid, repeating cellular units (e.g., a hexagonal/honeycomb pattern or spiral-wound corrugations), which provide surface area for ozone-laden air to contact. Each cell forms a closed passage or channel for gas flow from an inlet port to an outlet port, and hence can be referred to as a “closed cell” configuration. As the ozoneladen air flows through the closed channels and contacts the substrate and catalyst, ozone is converted into oxygen.

[0034] The desired operating temperature of the bleed air entering the inerting system 10 for the type of the ozone converter 12 is 300 °F or higher, preferably 350 °F or higher to ensure high ozone conversion efficiency. Such high temperature is desired because the precious metal catalysts employed in the core are not sufficiently “activated” at lower temperatures. Thus, the ozone converter 12 is located in the “hot” section of the inerting system 10, upstream of the heat exchanger 14 shown in Figure 1, where the temperature of the bleed air is typically in the range of

350 °F - 400 °F. [0035] However, air temperatures in the 350 °F - 400 °F range may be considered too high for the polymeric materials within the ASM 18. Thus, following ozone treatment in the ozone converter 12, air is cooled in the heat exchanger 14 to a temperature that is more appropriate for the ASM 18. The target temperature may vary depending on the specific ASM used. For example, a nominal inlet temperature for the ASM 18 could range from about 100 °F to 180 °F.

[0036] Further, air can include particulates and aerosols that, if ingested by the ASM 18, may potentially contaminate, plug, or otherwise degrade the fibers of the ASM 18. Thus, after cooling the air to the appropriate temperature via the heat exchanger 14, the air is filtered via the filter 16 to remove the particulates and aerosols. The resulting conditioned, pressurized air stream is fed to the ASM 18.

[0037] As mentioned above, to ensure long service life for the ASM 18, it is desirable to reduce the ozone concentration of the feed air via the ozone converter 12. For example, it may be desirable to reduce the ozone concentration to no more than 1 ppbv before it enters the hollow fiber membranes within the ASM 18. However, the inerting system 10 might not be able to achieve such reduction taking into consideration that ozone concentration of ambient air can range from about 50 ppbv at sea level to several hundred ppbv at high altitude, even exceeding 1,000 ppbv at particular high altitude, high latitude conditions. Such reduction may require the ozone converter 12 to have an ultra-high efficiency (e.g., in the 99.7-99.9% range or higher), which might not be achievable via the ozone converter 12 that is conventionally available.

[0038] For example, although the above-mentioned “closed cell” configuration facilitates computation and control of the total surface area within the ozone converter 12 based on the known geometry of each cell and the number of cells, such configuration may limit the ability of ozone molecules to contact the catalytic surface of each cell, thereby limiting its ozone conversion efficiency. Particularly, closed cells tend to act as channels or “flow straighteners,” where the flow field in each cell becomes generally aligned with the cell axis shortly after entering, and thus ozone molecules can contact only the cell walls through turbulence. If there is no turbulence, air that is flowing through a center of the cell (e.g., channel) might not interact with the catalytic inner surfaces of the walls. In other words, at least a portion of air flowing through the channel is trapped and cannot diffuse radially and might not contact the precious metal ozone catalyst. As such, the conversion efficiency is reduced. For example, new ozone converters of this type can achieve an ozone conversion efficiency in the range of 95% to 99%.

[0039] Further, the conversion efficiency degrades overtime as the precious metal catalyst adsorbs contaminants such as sulfur in the incoming bleed air stream. Thus, this type of ozone converter is typically removed and cleaned periodically, typically on the order of every 6,000 flight hours (FH), by which time the conversion efficiency percentage may have degraded to the low 90’s (e.g., 90%- 94)% or into the 80’s (e.g., down to 85%). This reduction has a detrimental effect on service life of the ASM 18.

[0040] For example, assuming ozone concentration of the air supply bled from the engine is 300 ppbv, Table 1 below shows the resulting ozone concentration for various ozone conversion efficiency values. As indicated by Table 1, efficiencies between 85% and 99% do not enable the ozone converter 12 to achieve the target 1 ppbv concentration.

Table 1 : Outlet Ozone Concentration vs. Conversion Efficiency (Inlet Ozone Cone. = 300 ppbv) [0041] As such, multiple ozone converters may be included in the inerting system 10, which increases system cost and weight. Alternatively, the lower efficiency is accepted, which causes negative consequences on the service life of the ASM 18, necessitating frequent maintenance and/or replacement, thereby increasing cost and downtime.

[0042] As described above, the inerting system 10 typically includes the filter 16 disposed upstream of the ASM 18 to remove particulates and aerosols that may exist in the bleed air. In some example inerting systems, an ozone converter may be integrated into the filter, such that the combination of the filter-integrated ozone converter and the ozone converter upstream of the heat exchanger enhance the ozone conversion efficiency.

[0043] Figure 2 illustrates a simplified schematic of an inerting system 26 having a filter-integral ozone converter, according to an example. The inerting system 26 has components that are identical to those of the inerting system 10 and such components are designated by the same reference numbers.

[0044] The inerting system 26 includes a filter 28 that has an ozone converter integrated therewith. With this configuration, the functionality of the filter 28 is augmented to incorporate ozone removal or conversion capability. As shown in Figure 2, this type of ozone removal device integrated in the filter 28 is often used in conjunction with a conventional, high-temperature ozone converter such as the ozone converter 12. In such a configuration, the ozone reduction achieved with the filter-integral ozone converter can be considered supplemental to that of the ozone converter 12.

[0045] If sufficient catalyst is included in the filter 28, it can achieve ozone conversion efficiencies of 99% or higher when new. However, given its typical role of providing “supplemental” ozone protection, there has not been as much emphasis on achieving such a high conversion efficiency. Further, due to the multiple functions served by the filter 28 (e g., particulate, aerosol, and ozone removal), the filter element is replaced periodically, with typical service intervals ranging from 7,000 to 12,000 FH, thus increasing maintenance cost and downtime.

[0046] Another concern with filter-integral ozone converters is that low-cost replacement filter elements may be available from multiple suppliers in the aftermarket, and such low-cost versions may contain less effective ozone converters or even omit the ozone converter element altogether. Thus, once the inerting system 26 reaches the first service interval at which the filter element is replaced, there is no guarantee that the same amount of ozone protection for the ASM 18 is retained as originally configured or intended.

[0047] As such, it may be desirable to configure an inerting system to have an ultra-high ozone removal efficiency (e.g., greater than 99.7%), while alleviating deficiencies of the inerting systems 10, 26. Disclosed next is an inerting system that is capable of achieving such ultra-high ozone conversion efficiency. The enhanced conversion efficiency renders the disclosed inerting system a stand-alone ASM-integral ozone converter that can protect the ASM without supplementation from conventional ozone converters (e g., the ozone converter 12) or filter-integrated ozone converters.

[0048] Figure 3 illustrates a simplified schematic of an inerting system 100 having an ASM 102 with an ozone converter integrated therewith, according to an example implementation. The inerting system 100 includes a heat exchanger 104 that is similar to the heat exchanger 14, and includes a filter 106 that is similar to the filter 16.

[0049] In the inerting system 100, the ozone reduction capability is integrated directly into the ASM 102, where an ozone converter is integrated into an inlet endcap of the ASM 102, for example. In such an arrangement, the feed air flows into an inlet port 108 of the ASM 102 and through the ozone converter before it enters the hollow fiber membranes within the ASM 102. The ASM 102 includes an outlet port 110 that is similar to the outlet port 24 described above, and also includes a discharge port 112 that is similar to the discharge port 22 described above.

[0050] Figure 4 illustrates a simplified, partial cross-sectional view of the ASM 102, according to an example implementation. Figure 4 particularly depicts the inlet portion of the ASM 102.

[0051] The ASM 102 has an inlet endcap 200 that is coupled to a housing 202 of the ASM 102. The inlet endcap 200 can be coupled to the housing 202 in various ways. For example, the inlet endcap 200 can have flange 204 at its distal end interfacing with a respective flange 206 at a proximal end of the housing 202. The flanges 204, 206 can then be coupled to each other via fasteners, clamps, etc. For example, a circumferential hoop (e.g., of a V-band clamp) can be used with a tangential bolt to secure the hoop and couple the flanges 204, 206 to each other. In other examples, the inlet endcap 200 can be threaded into the housing 202.

[0052] The housing 202 includes the discharge port 112. The discharge port 112 is disposed in a transversal (e.g., perpendicular) direction relative to the inlet port 108 as depicted.

[0053] An outlet endcap (not shown) can be attached similarly to the housing 202 at a distal end thereof. Together, the assembly of the inlet endcap 200, the housing 202, and the outlet endcap forms a pressure vessel around a bundle 208 of hollow fiber membranes. As mentioned above, the bundle 208 can include a plurality (e.g., tens of thousands) of such hollow fiber membranes that filter out oxygen and allow nitrogen-rich air to pass therethrough to the outlet port 110, then to a fuel tank of an aircraft.

[0054] Particularly, oxygen molecules diffuse through the polymeric material of the hollow fiber membranes of the bundle 208 more readily than nitrogen. In other words, the bundle 208 allows preferential diffusion of oxygen therethrough. Oxygen-rich air that has permeated through the fiber membranes of the bundle 208 is then discharged as waste through the discharge port 112. As such, the discharge port 112 can be referred to as a permeate gas port or waste port. On the other hand, nitrogen-rich air flows through the hollow fibers to the outlet port 110 to be provided to the fuel tank.

[0055] To prevent air received at the inlet port 108 from flowing in respective spaces between the hollow fibers of the bundle 208, the ASM 102 includes an inlet tubesheet 210 at the proximal end of the bundle 208 and another tubesheet (not shown) at the distal end thereof. In an example, the tubesheets can include epoxy tubesheets, which capture the hollow fibers to hold them in place and provide an airtight seal between the fibers. In an example, the inlet tubesheet 210 can be in the form of liquid epoxy that fills the spaces between the fibers of the bundle 208. The epoxy then hardens into the inlet tubesheet 210. The inlet tubesheet 210 thus plugs all the spaces or gaps between the fibers, thereby forcing air to flow through the bores of the hollow fibers.

[0056] The inlet tubesheet 210 can additionally provide structural support for the fibers of the bundle 208 to prevent them from moving within the housing 202. The inlet tubesheet 210 is also strong and sufficiently structurally sound to withstand the pressure differential between pressure level at the inlet port 108 and the outlet port 110, such that the inlet tubesheet 210 does not bend or break.

[0057] Further, ozone-laden feed air entering the ASM 102 through the inlet port 108 in the inlet endcap 200 expands to a larger diameter of the inlet endcap 200, and then flows through an ozone converter disk 212 where ozone molecules (Ch) (which are damaging to the bundle 208) are catalytically converted to oxygen molecules (O2). In an example, the ozone converter disk 212 can be cylindrically shaped. [0058] The ASM 102 further includes a filter element 214 that is interposed between the ozone converter disk 212 and the inlet tubesheet 210. The filter element 214 is configured to catch or filter catalyst debris that may be dislodged from the ozone converter disk 212 during operation and prevent it from migrating further downstream.

[0059] The ASM 102 can also include a gasket or seal 216 disposed within the inlet endcap 200 upstream of the ozone converter disk 212, such that the ozone converter disk 212 is sandwiched or interposed between the seal 216 and the filter element 214. In examples, the seal 216 can be ring-shaped or annular. The seal 216 is configured to prevent the feed air received through the inlet port 108 from flowing around the ozone converter disk 212. Rather, air is forced to flow through the ozone converter disk 212.

[0060] The seal 216 also operates as a compliant member to facilitate snug fit-up of or securing the ozone converter disk 212 and the filter element 214 between the upstream face of the inlet tubesheet 210 and the interior surface of the inlet endcap 200, while accommodating manufacturing tolerances. The implementation shown in Figure 4 is an example implementation, and various arrangements of this gasket/seal are feasible.

[0061] In examples, the ASM 102 can include another seal 218 (e.g., a radial seal) disposed about the inlet tubesheet 210. A similar seal can be disposed about the outlet tubesheet at the other end of the ASM 102. The seal 218 may supplement the seal 216 to seal the discharge port 112 from the inlet port 108 and inlet air stream.

[0062] Referring to Figures 3-4 together, with the configuration of the inerting system 100, the ASM 102 is located downstream of the heat exchanger 104. Thus, the air temperature at the inlet port 108 of the ASM 102 can be about 100 °F to 180 °F, which is too low for the precious metal catalysts used in the ozone converter 12 of the configurations shown in Figures 1-2 to be effective. [0063] Therefore, the ASM 102, and particularly the ozone converter disk 212 integrated therein, has “low-temperature” catalysts such as activated carbon and/or activated manganese oxide, which are effective in this temperature range. In the ozone converter disk 212, the catalyst is incorporated in a pliable material or substrate that has an “open cell” structure.

[0064] For example, the substrate can include a carbon cloth and/or a manganese oxide coated reticulated foam, felt, or fiber. Such media can generally be classified as “open cell”, as they do not constrain the gas flow through individual closed cell passages/channels from inlet to outlet as described with respect to conventional, high-temperature ozone converters such as the ozone converter 12.

[0065] An open cell substrate such as a reticulated foam, for example, enables the inlet air stream received at the inlet port 108 to spread or diffuse in various directions (e.g., axially and laterally/radially) and follow a tortuous path as it flows through the ozone converter disk 212. During transit through such complex, three-dimensional structure, ozone molecules have a greater probability of contacting a catalytic surface than if the flow is constrained by a closed cell structure of the same thickness.

[0066] Further, in examples, the substrate of the ozone converter disk 212 having an open cell structure can have different porosities, thereby providing a larger surface area per unit volume compared to a closed cell structure. Specifically, the ozone converter disk 212 of the ASM 102 can be configured such that it has a coated surface area per unit superficial volume (which is typically referred to as “specific surface area”) of at least 8x10⁴ centimeter²/centimeter³ (cm²/cm³), and more preferably 9xl0⁴ cm²/cm³ or higher.

[0067] Substrates that have open cell structure and the above-mentioned desired specific surface area criteria include, but are not limited to, various foams, felts and fibers. Example materials include polyurethane foam, aluminum foam, reticulated vitreous carbon (RVC) foam, silicon carbide foam, Fecralloy felt, and stainless steel felt, to name a few. These substrates can differ in terms of mechanical strength, rigidity, weight per unit volume, cost, catalyst adhesion, pressure drop, etc., and thus the substrate can be chosen to balance such properties, while having an open cell structure and the desired specific surface area.

[0068] Figures 5-6 provide examples of an open cell structure of the ozone converter disk 212. Particularly, Figure 5 illustrates an enlarged view of a portion of a substrate of the ozone converter disk 212 made of reticulated foam, and Figure 6 illustrates an enlarged view of a portion of a substrate of the ozone converter disk 212 made of felt, according to example implementations.

[0069] The reticulated foam or felt material of the substrate has a catalyst such as manganese oxide deposited thereon. These example structures enable the air stream to flow in various directions, as opposed to being streamlined through channels, and thereby enhances the likelihood of interaction between the air and the catalyst and increases the conversion efficiency.

[0070] When new, an ASM-integral ozone converter configured per the above description can achieve ozone conversion efficiencies of 99.9% or better with residence times in the range of 10 to 40 milliseconds (ms). Residence time refers to the duration of time that air spends within the ozone converter disk 212, for example. Such range of residence times covers the range of operating conditions expected for the ASM 102 during cruise and top of descent flight phases of an aircraft. Residence time can be changed via a valve disposed downstream of the ASM 102 to change the air flow rate therethrough.

[0071] Further, testing has shown that after long-term operation and exposure to high levels of ozone, humidity, contaminants and other stressors of the aircraft environment (e.g., vibration, shock, pressure and altitude cycles, etc ), only minimal performance degradation is observed, with the ASM-integral ozone converter retaining an ozone conversion efficiency of 99.7% or better.

[0072] These efficiencies enable reducing ozone concentration to below 1 ppbv. For example, assuming ozone concentration at the inlet port 108 is 300 ppbv, Table 2 below shows the resulting ozone concentration at the outlet port 110 for various ozone conversion efficiencies greater than or equal to 99.7%. As indicated by Table 2, efficiencies between 99.7% and 99.95% cause the ASM-integral ozone converter of the ASM 102 to reduce ozone concentration to less than the target or desired 1 ppbv concentration.

Table 2: Outlet Ozone Concentration vs. Conversion Efficiency (Inlet Ozone Cone. = 300 ppbv) [0073] The effectiveness of the ozone protection provided by the ozone converter disk 212 integrated within the ASM 102 in this stand-alone configuration of Figure 3 is further illustrated via the following testing examples.

[0074] A first test has considered a single-aisle aircraft flying at an altitude of 36,000 feet (ft) in a region where the ambient ozone concentration is 300 ppbv, such as Eastern North America at a latitude of 40 - 45° north. An ASM-integral ozone converter such as the ASM 102 with the ozone converter disk 212 is used with no other ozone conversion devices in the inerting system. The ozone converter disk 212 is constructed of an open-cell polyurethane foam with a thickness of 0.5”, coated with an active manganese oxide catalyst to yield a specific surface area of 9.6xl0⁴ cm²/cm³. The weight of the ozone converter integrated into the ASM 102 is less than 0.25 pound (lb). [0075] During the cruise phase of flight, at nominal ASM inlet conditions of 30 pounds per square in gauge (psig) and 104 °F, the residence time of the feed air within the ozone converter disk 212 is approximately 36 ms. Under these conditions, test data shows the ASM 102 ozone converter disk 212 integrated therein achieves an ozone conversion efficiency of 99.95% when new. Assuming the air enters the ASM 102 with an ozone level of 300 ppbv, this ultra-high conversion efficiency results in an outlet ozone concentration from the converter disk of 0.15 ppbv as indicated in Table 2 above, thereby achieving the target value of no more than 1 ppbv. After operating for the equivalent of tens of thousands of hours in this environment, test data indicates the ozone conversion efficiency is relatively unaffected, reducing to approximately 99.94%. This translates to an outlet ozone concentration of only 0.18 ppbv.

[0076] A second test has considered a single aisle aircraft flying in the same region and altitude as in first test, but with ASM inlet conditions of 25 psig and 140 °F at Top of Descent flight phase. Under these conditions the residence time through the same ASM-integral ozone converter (i.e., the ASM 102) is approximately 20 ms, shorter than in the first test. For instance, a valve downstream of the ASM 102 is opened further compared to the first test to increase air flow rate and decrease residence time.

[0077] In this second test, data indicates that the ASM 102 similarly achieves an ozone conversion efficiency of 99.95% when new, which decreases to approximately 99.90% after the equivalent of tens of thousands of hours in service. For an inlet ozone concentration of 300 ppbv, these conversion efficiency figures translate to outlet ozone concentrations of 0.15 and 0.3 ppbv, respectively. Both concentrations meet the target ozone concentration of 1 ppbv or lower before the feed air enters the fibers of the bundle 208. [0078] The first and second tests described above indicate that the ASM 102 having the ozone converter disk 212 with the characteristics described above can achieve ozone conversion efficiency values of 99.9% or better across a range of typical flow conditions for an ASM on a single aisle aircraft. Even if efficiency decreases to 99.7% at more extreme conditions (e.g., residence times down to 10 ms), Table 2 shows that the outlet ozone concentration from this ASM- integral ozone converter is less than 1 ppbv in a stand-alone configuration, providing the desired ozone protection for the fibers of the bundle 208 to achieve long service life for the ASM 102.

[0079] In particular, the ultra-high conversion efficiency of the ozone converter disk 212 integrated within the ASM 102 enables the ASM 102 to be a stand-alone ozone converter, without needing to use additional or supplemental ozone conversion devices. Such ultra-high conversion is enabled in part by the open cell structure of the ozone converter disk 212.

[0080] In comparison, if a conventional, high-temperature ozone converter (e.g., the ozone converter 12 described above) is exposed to 300 ppbv inlet ozone concentration, its conversion efficiency may range from 99% (best case at low flow rate, new condition) to potentially 85% (high flow rate, fouled condition). As indicated by Table 1 above, this translates to anywhere from 3 to 45 ppbv ozone concentration at the fibers of an ASM, which does not meet the 1 ppbv target, if no other means of ozone destruction is present in the inerting system.

[0081] Thus, the configuration of the inerting system 100 with an ozone converter (e.g., the ozone converter disk 212) integrated in the ASM 102 may provide several advantages over conventional inerting systems. Particularly, the inerting system 100 with the ASM-integral ozone converter can provide a “stand-alone” configuration where no other ozone converter might be needed. The inerting system 100 may thus have a lower initial cost compared to conventional systems due to elimination of other ozone conversion devices. This aspect may be particularly beneficial when considering the costly, precious metal catalysts used in conventional, high temperature ozone converters compared to low-temperature catalysts such as manganese oxide.

[0082] Also, the inerting system 100 has a lower weight compared to conventional systems as the inerting system 100 may eliminate the need for other ozone conversion devices. For example, a weight reduction of about 1.5 lb or more can be achieved, which is significant in the highly weightsensitive aircraft industry.

[0083] Further, compared to the inerting system 26 having the filter-integral ozone converter, the inerting system 100 reduces or eliminates on-going maintenance costs associated with cleaning and/or filter element replacement. The inerting system 100 may also eliminate concerns related to potentially inferior ozone protection being provided by aftermarket filter manufacturers if a filterintegral ozone converter were to be used.

[0084] Further, the configuration of the inerting system 100 facilitates scaling ozone protection with the size of the aircraft. Particularly, for larger aircraft requiring a set of ASMs, each ASM can be protected with its own ASM-integral ozone converter rather than relying on larger conventional or filter-integral ozone converters upstream of the set of ASMs.

[0085] Although Figure 3 illustrates a stand-alone configuration where the only ozone conversion device in the inerting system 100 is integrated into the ASM 102 and is capable of achieving target ozone concentrations and the advantages associated with such configuration, in other example implementations, additional ozone converters can be used. For example, such converters may be added for redundancy or further enhancement of conversion efficiency.

[0086] Figure 7 illustrates a simplified schematic of an inerting system 300 having the ASM 102 with an ozone converter integrated therewith and another ozone converter 302 upstream of the heat exchanger 104, according to an example implementation. The ozone converter 302 disposed in a high temperature zone and may be similar to the ozone converter 12 described above. The ozone converter 302 may thus use one or more precious metal ozone catalysts suitable for high- temperature ozone conversion.

[0087] Figure 8 illustrates a simplified schematic of an inerting system 400 having the ASM 102 with an ozone converter integrated therewith and a filter 402 that has an ozone converter integrated therewith, according to an example implementation. The filter 402 may be similar to the filter 28 described above, for example. As such, in addition to the ozone converter integrated into the ASM 102, the functionality of the filter 402 is augmented to incorporate ozone removal or conversion capability.

[0088] Figure 9 illustrates a simplified schematic of an inerting system 500 having the ASM 102 with an ozone converter integrated therewith, the ozone converter 302 upstream of the heat exchanger 104, and the filter 402 that has an ozone converter integrated therewith, according to an example implementation. The inerting system 500 thus combines three ozone converters and features from the inerting systems 100, 300, 400.

[0089] The detailed description above describes various features and operations of the disclosed systems with reference to the accompanying figures. The illustrative implementations described herein are not meant to be limiting. Certain aspects of the disclosed systems can be arranged and combined in a wide variety of different configurations, all of which are contemplated herein.

[0090] Further, unless context suggests otherwise, the features illustrated in each of the figures may be used in combination with one another. Thus, the figures should be generally viewed as component aspects of one or more overall implementations, with the understanding that not all illustrated features are necessary for each implementation. [0091] Additionally, any enumeration of elements, blocks, or steps in this specification or the claims is for purposes of clarity. Thus, such enumeration should not be interpreted to require or imply that these elements, blocks, or steps adhere to a particular arrangement or are carried out in a particular order.

[0092] Further, devices or systems may be used or configured to perform functions presented in the figures. In some instances, components of the devices and/or systems may be configured to perform the functions such that the components are actually configured and structured (with hardware and/or software) to enable such performance. In other examples, components of the devices and/or systems may be arranged to be adapted to, capable of, or suited for performing the functions, such as when operated in a specific manner.

[0093] By the term “substantially” or “about” it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those with skill in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide.

[0094] The arrangements described herein are for purposes of example only. As such, those skilled in the art will appreciate that other arrangements and other elements (e.g., machines, interfaces, operations, orders, and groupings of operations, etc.) can be used instead, and some elements may be omitted altogether according to the desired results. Further, many of the elements that are described are functional entities that may be implemented as discrete or distributed components or in conjunction with other components, in any suitable combination and location.

[0095] While various aspects and implementations have been disclosed herein, other aspects and implementations will be apparent to those skilled in the art. The various aspects and implementations disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope being indicated by the following claims, along with the full scope of equivalents to which such claims are entitled. Also, the terminology used herein is for the purpose of describing particular implementations only, and is not intended to be limiting.

[0096] Embodiments of the present disclosure can thus relate to one of the enumerated example embodiments (EEEs) listed below.

[0097] EEE 1 is an air separation module comprising: a housing; an inlet endcap coupled to the housing and having an inlet port for receiving air flow; an ozone converter disk disposed within the inlet endcap, wherein the ozone converter disk has an open cell structure that allows air to be diffused in radial and axial directions such that air follows a tortuous path as air traverses the ozone converter disk, and wherein the ozone converter disk includes a catalyst that converts ozone in the air into another substance; a bundle of a plurality of hollow fibers disposed within the housing, wherein the bundle receives air from the ozone converter disk and separates air into an oxygenrich portion and a nitrogen-rich portion; a discharge port through which the oxygen-rich portion is discharged to an external environment; and an outlet port through which the nitrogen-rich portion is provided downstream to a fuel tank of an aircraft.

[0098] EEE 2 is the air separation module of EEE 1, wherein the ozone converter disk has a substrate having the open cell structure.

[0099] EEE 3 is the air separation module of EEE 2, wherein the substrate is made of reticulated foam or felt having the open cell structure.

[00100] EEE 4 is the air separation module of any of EEEs 2-3, wherein the substrate is coated with the catalyst. [00101] EEE 5 is the air separation module of any of EEEs 1-4, wherein the catalyst comprises activated manganese oxide.

[00102] EEE 6 is the air separation module of any of EEEs 1 -5, further comprising: a seal disposed within the inlet endcap, upstream of the ozone converter disk, wherein the seal prevents air received through the inlet port from flowing around the ozone converter disk such that air is forced to flow through the ozone converter disk.

[00103] EEE 7 is the air separation module of EEE 6, further comprising: a filter element, wherein the ozone converter disk is interposed between the seal and the filter element, wherein the filter element is configured to filter catalyst debris dislodged from the ozone converter disk during operation.

[00104] EEE 8 is the air separation module of any of EEEs 1-7, further comprising: an inlet tubesheet coupled to a proximal end of the bundle and configured to prevent air from flowing through respective spaces between the plurality of hollow fibers of the bundle such that air is forced to flow through the plurality of hollow fibers.

[00105] EEE 9 is the air separation module of EEE 8, further comprising: a seal disposed about the inlet tubesheet and configured to seal the discharge port from the inlet port.

[00106] EEE 10 is the air separation module of any of EEEs 1-9, wherein the ozone converter disk has a coated surface area per unit volume of at least 8xl0⁴ centimeter²/centimeter³ (cm²/cm³), and more preferably 9xl0⁴ cm²/cm³ or higher.

[00107] EEE 11 is the air separation module of any of EEEs 1-10, wherein a conversion efficiency of the ozone converter disk is at least 99.7%. [00108] EEE 12 is an inerting system comprising: a heat exchanger configured to receive air bled from an engine of an aircraft and cool the air; a filter disposed downstream of the heat exchanger and configured to remove particulates and aerosols from the air; and the air separation module of any of EEEs 1-11 disposed downstream from the filter. For example, the air separation module comprises: (i) a housing, an inlet endcap coupled to the housing and having an inlet port for receiving air flow, (ii) an ozone converter disk disposed within the inlet endcap, wherein the ozone converter disk has an open cell structure that allows air to be diffused in radial and axial directions such that air follows a tortuous path as air traverses the ozone converter disk, and wherein the ozone converter disk includes a catalyst that converts ozone in the air into another substance, (iii) a bundle of a plurality of hollow fibers disposed within the housing, wherein the bundle receives air from the ozone converter disk and separates air into an oxygen-rich portion and a nitrogen-rich portion, (iv) a discharge port through which the oxygen-rich portion is discharged to an external environment, and (v) an outlet port through which the nitrogen-rich portion is provided downstream to a fuel tank of the aircraft.

[00109] EEE 13 is the inerting system of EEE 12, wherein the ozone converter disk has a substrate made of reticulated foam or felt having the open cell structure.

[00110] EEE 14 is the inerting system of EEE 13, wherein the substrate is coated with the catalyst comprising activated manganese oxide.

[00111] EEE 15 is the inerting system of any of EEEs 12-14, wherein the air separation module further comprises: a seal disposed within the inlet endcap, upstream of the ozone converter disk, wherein the seal prevents air received through the inlet port from flowing around the ozone converter disk such that air is forced to flow through the ozone converter disk; and a fdter element, wherein the ozone converter disk is interposed between the seal and the fdter element, wherein the filter element is configured to filter catalyst debris dislodged from the ozone converter disk during operation.

[00112] EEE 16 is the inerting system of any of EEEs 12-15, wherein the air separation module further comprises: an inlet tubesheet coupled to a proximal end of the bundle and configured to prevent air from flowing through respective spaces between the plurality of hollow fibers of the bundle such that air is forced to flow through the plurality of hollow fibers.

[00113] EEE 17 is the inerting system of any of EEEs 12-16, wherein the ozone converter disk has a coated surface area per unit volume of at least 8xl0⁴ centimeter²/centimeter³ (cm²/cm³), and more preferably 9xl0⁴ cm²/cm³ or higher.

[00114] EEE 18 is the inerting system of any of EEEs 12-17, wherein a conversion efficiency of the ozone converter disk is at least 99.7% without having additional ozone converters.

[00115] EEE 19 is the inerting system of any of EEEs 12-18, further comprising: an ozone converter disposed in a high temperature zone upstream of the heat exchanger.

[00116] EEE 20 is the inerting system of any of EEEs 12-19, wherein the filter includes an additional ozone converter integrated within the filter.

Claims

CLAIMS What is claimed is:

1 . An air separation module comprising: a housing; an inlet endcap coupled to the housing and having an inlet port for receiving air flow; an ozone converter disk disposed within the inlet endcap, wherein the ozone converter disk has an open cell structure that allows air to be diffused in radial and axial directions such that air follows a tortuous path as air traverses the ozone converter disk, and wherein the ozone converter disk includes a catalyst that converts ozone in the air into another substance; a bundle of a plurality of hollow fibers disposed within the housing, wherein the bundle receives air from the ozone converter disk and separates air into an oxygen-rich portion and a nitrogen-rich portion; a discharge port through which the oxygen-rich portion is discharged to an external environment; and an outlet port through which the nitrogen-rich portion is provided downstream to a fuel tank of an aircraft.

2. The air separation module of claim 1, wherein the ozone converter disk has a substrate having the open cell structure.

3. The air separation module of claim 2, wherein the substrate is made of reticulated foam or felt having the open cell structure.

4. The air separation module of claim 2, wherein the substrate is coated with the catalyst.

5. The air separation module of claim 1, wherein the catalyst comprises activated manganese oxide.

6. The air separation module of claim 1, further comprising: a seal disposed within the inlet endcap, upstream of the ozone converter disk, wherein the seal prevents air received through the inlet port from flowing around the ozone converter disk such that air is forced to flow through the ozone converter disk.

7. The air separation module of claim 6, further comprising: a filter element, wherein the ozone converter disk is interposed between the seal and the filter element, wherein the filter element is configured to filter catalyst debris dislodged from the ozone converter disk during operation.

8. The air separation module of claim 1, further comprising: an inlet tubesheet coupled to a proximal end of the bundle and configured to prevent air from flowing through respective spaces between the plurality of hollow fibers of the bundle such that air is forced to flow through the plurality of hollow fibers.

9. The air separation module of claim 8, further comprising: a seal disposed about the inlet tubesheet and configured to seal the discharge port from the inlet port.

10. The air separation module of claim 1 , wherein the ozone converter disk has a coated surface area per unit volume of at least 8xl0⁴ centimeter²/centimeter³ (cm²/cm³), and more preferably 9xl0⁴ cm²/cm³ or higher.

11. The air separation module of claim 1, wherein a conversion efficiency of the ozone converter disk is at least 99.7%.

12. An inerting system comprising: a heat exchanger configured to receive air bled from an engine of an aircraft and cool the air; a filter disposed downstream of the heat exchanger and configured to remove particulates and aerosols from the air; and an air separation module disposed downstream from the filter, wherein the air separation module comprises: (i) a housing, an inlet endcap coupled to the housing and having an inlet port for receiving air flow, (ii) an ozone converter disk disposed within the inlet endcap, wherein the ozone converter disk has an open cell structure that allows air to be diffused in radial and axial directions such that air follows a tortuous path as air traverses the ozone converter disk, and wherein the ozone converter disk includes a catalyst that converts ozone in the air into another substance, (iii) a bundle of a plurality of hollow fibers disposed within the housing, wherein the bundle receives air from the ozone converter disk and separates air into an oxygen-rich portion and a nitrogen-rich portion, (iv) a discharge port through which the oxygen-rich portion is discharged to an external environment, and (v) an outlet port through which the nitrogen-rich portion is provided downstream to a fuel tank of the aircraft.

13. The inerting system of claim 12, wherein the ozone converter disk has a substrate made of reticulated foam or felt having the open cell structure.

14. The inerting system of claim 13, wherein the substrate is coated with the catalyst comprising activated manganese oxide.

15. The inerting system of claim 12, wherein the air separation module further comprises: a seal disposed within the inlet endcap, upstream of the ozone converter disk, wherein the seal prevents air received through the inlet port from flowing around the ozone converter disk such that air is forced to flow through the ozone converter disk; and a filter element, wherein the ozone converter disk is interposed between the seal and the filter element, wherein the filter element is configured to filter catalyst debris dislodged from the ozone converter disk during operation.

16. The inerting system of claim 12, wherein the air separation module further comprises: an inlet tubesheet coupled to a proximal end of the bundle and configured to prevent air from flowing through respective spaces between the plurality of hollow fibers of the bundle such that air is forced to flow through the plurality of hollow fibers.

17. The inerting system of claim 12, wherein the ozone converter disk has a coated surface area per unit volume of at least 8xl0⁴ centimeter²/centimeter³ (cm²/cm³), and more preferably 9xl0⁴ cm²/cm³ or higher.

18. The inerting system of claim 12, wherein a conversion efficiency of the ozone converter disk is at least 99.7% without having additional ozone converters.

19. The inerting system of claim 12, further comprising: an ozone converter disposed in a high temperature zone upstream of the heat exchanger.

20. The inerting system of claim 12, wherein the fdter includes an additional ozone converter integrated within the fdter.