Carbon dioxide adsorption apparatus and adsorption element and method for manufacture thereof

A carbon dioxide adsorption element rapidly adsorbs a large amount of carbon dioxide, and regenerates amine groups for carbon dioxide adsorption rapidly and uniformly with high-temperature air. The carbon dioxide adsorption element 110 for adsorbing carbon dioxide in air comprises a foil-like or plate-like support member 111, a porous aluminum oxide film 112 covering the support member 111, and the amine groups 113 clinging to the inner surface of each pore 112a of the film 112 for carbon dioxide adsorption. The film 112 is formed by oxidation of aluminum or aluminum alloy. The depth direction of each pore 112a of the film is the thickness direction of the support member 111.

TECHNICAL FIELD

The present invention relates to a carbon dioxide adsorption apparatus and adsorption element used for adsorbing carbon dioxide in the air, for example, inside a cabin of an aircraft, and to a method for manufacturing the apparatus and element.

BACKGROUND ART

An element with porous resin fine powder or a grid-shaped structure made from ceramic such as silicon dioxide or alumina to which amine groups having excellent carbon dioxide adsorption characteristic cling is known as a carbon dioxide adsorption element. To be more precise, it was proposed to construct an air flow path filled with fine powder having amine groups clinging thereto or to charge fine powder having amine groups clinging thereto into an air flow path consisting of grid-shaped structure having amine groups clinging thereto so as to adsorb carbon dioxide contained in the air flowing through the air flow path (refer to patent documents 1, and 2).Patent document 1: Japanese Examined Patent Applications HEI No. 3-7412Patent document 2: Japanese Examined Patent Applications HEI No. 3-39729

DISCLOSURE OF THE INVENTION

Problem to be Solved by the Invention

When fine powder having amine groups clinging thereto are charged into an air flow path, as in the conventional configuration, resistance to air flow increases; therefore the air has to flow at a large volume flow rate in order to adsorb the carbon dioxide contained in the air in a space of a large volume, and rapid adsorption is difficult. Furthermore, when a regeneration treatment is conducted by which the adsorbed carbon dioxide is released by heating the amine groups with high-temperature air, the resistance to the flow of the high-temperature air also rises, thereby rapid regeneration treatment is prevented. Moreover, the heat of the high-temperature air for regeneration is difficult to transfer rapidly and uniformly to the amine groups in the conventional carbon dioxide adsorption element, so that rapid regeneration treatment is difficult. The conventional carbon dioxide adsorption element are thus not suitable for adsorbing carbon dioxide contained in the air in a closed space accommodating a large number of people.

For example, in a large aircraft, if the amount of air extracted from engine for a cabin is reduced in order to maintain the engine performance, the rate of fresh air in the cabin decreases. However, if the rate of fresh air taken from the outside of the airplane is reduced, the concentration of carbon dioxide fails to satisfy the requirement of 5000 ppm (0.5%) or less, which is a regulation recommended by the FAA (Federal Aviation Administration, USA). Because the concentration of carbon dioxide in the alveoli of human lung is about 3%, dangerous conditions cannot be immediately created at the 5000 ppm; however, an effect such as reduction of mental capacity of some people can be produced at a higher concentration. For this reason, it is desirable that carbon dioxide is rapidly adsorbed and the adsorbed carbon dioxide is rapidly released to regenerate the amine groups. Furthermore, in large aircrafts, the carbon dioxide concentration should be low and less than 0.5% while the internal volume of fuselage is large, the flow rate of air passing through the carbon dioxide adsorption zone has to be thus increased in order to remove the carbon dioxide from the air in the aircraft. However, electric energy required for air compression is necessary to compensate for pressure loss in the carbon dioxide adsorption zone, so that load on the engine having a power generator increases; therefore, it is desired that this pressure loss is reduced. Furthermore, it is desirable that the adsorption of carbon dioxide is conducted with good efficiency, but energy consumption treatments such as a pressurization treatment of circulating air or the like is restricted because the use of energy in the aircraft is restricted, and a pressure-resistant structure capable of treating high pressure is unsuitable for aircrafts that require weight reduction because the weight increases. Moreover, when it is used in aircrafts, normal functions should be maintained even in the environment involving shaking, vibrations, and acceleration, and also small size and small weight are required. It is an object of the present invention to resolve those problems.

Means for Solving the Problems

The carbon dioxide adsorption element for adsorbing carbon dioxide contained in air in accordance with an aspect of the present invention comprises a foil-like or plate-like support member, a porous aluminum oxide film covering the support member, and amine groups clinging to the inner surface of each pore of the film for carbon dioxide adsorption, wherein the film is formed by oxidation of aluminum or aluminum alloy, and the depth direction of each pore of the film is the thickness direction of the support member. As a result, a carrier of the amine groups is structured by the support member and porous film formed on the surface of the support member.

The method for manufacturing a carbon dioxide adsorption element in accordance with the present invention comprises the steps of forming a foil-like support member made from aluminum or aluminum alloy, forming a porous film by conducting anodization of the surface layer of the support member, and causing amine groups for carbon dioxide adsorption to cling to the inner surface of each pore of the film. Alternatively, the method comprises the steps of forming a plate-like support member in which at least the surface layer is made from aluminum or aluminum alloy, forming a porous film by conducting anodization of the surface layer of the support member, and causing amine groups for carbon dioxide adsorption to cling to the inner surface of each pore of the film.

In accordance with the present invention, because the foil-like or plate-like support member is thin, the resistance to the flow of air can be reduced and the adsorption of carbon dioxide contained in the air can be rapidly performed without increasing the pressure loss in the air flow path constituted by the carbon dioxide adsorption element in accordance with the present invention, by causing the air to flow along the surface of the support member in the air flow path. Furthermore, because the support member is thin and has a small weight, the carbon dioxide adsorption element is reduced in size and weight, the structure thereof is simplified, and it can function normally even in an environment where it is subjected to shaking, vibrations, and acceleration; furthermore, flow paths along the surface of the support member of the carbon dioxide adsorption element can be configured by winding or bending the carbon dioxide adsorption element into a roll, or by stacking a plurality of carbon dioxide adsorption elements. When plate-like carbon dioxide adsorption elements are stacked, gaps constituting air flow paths between the surfaces of stacked carbon dioxide adsorption elements can be ensured by forming multiple protrusions projecting from the surfaces of the carbon dioxide adsorption elements or by inserting spacers. A large number of protrusions that project from the surfaces of the carbon dioxide adsorption elements can be formed by providing peaks and valleys on the support member, e.g., by pressing prior to forming the film.

It is preferred that the support member is made from aluminum or aluminum alloy, and that the film is formed by oxidation of the surface layer of the support member. Because the amine groups can adsorb carbon dioxide contained in the air and can release the adsorbed carbon dioxide when the temperature rises above that at the time of adsorption process, the amine groups can be regenerated by causing the high-temperature air to flow in the air flow path. Because the support member is made from aluminum or aluminum alloy with excellent thermal conductivity, even if it is heated locally, the heat is diffused and distributed uniformly, thereby preventing the amine groups from transformation and degradation due to increase in temperature. As a result, the carbon dioxide adsorption elements can be heated so that a uniform temperature distribution is achieved and can be heated uniformly and rapidly to a temperature suitable for regenerating the amine groups with the heat of the high-temperature air.

The carbon dioxide adsorption element for adsorbing carbon dioxide contained in air in accordance with another aspect of the present invention comprises a support member, a porous film covering the support member, and amine groups clinging to the inner surface of each pore of the film for carbon dioxide adsorption, wherein the support member includes an element that is heated by electric energy, and carbon dioxide adsorbed by the amine groups is released by heating the element.

As a result, the temperature of the element rises to a level suitable for regenerating the amine groups within a short time by electric energy, so that the regeneration of amine groups can be carried out rapidly. Therefore, the cycle of carbon dioxide adsorption and regeneration can be shortened, so the size and weight of the carbon dioxide adsorption apparatus can be reduced even when a large amount of carbon dioxide is treated, making it suitable for installation in an aircraft. In this case, it is preferred that the support member is foil-like or plate-like, and the depth direction of each pore of the film is the thickness direction of the support member. Any porous material can be used for the covering film, but a porous aluminum oxide formed by oxidizing aluminum or aluminum alloy is preferred.

Furthermore, it is preferred that the element is an electric resistance element having electrical conductivity and connected to a power supply unit for resistance heating, and that carbon dioxide adsorbed by the amine groups is released by resistance heating of the electric resistance element. As a result, the temperature of the electric resistance element rises to the temperature suitable for regenerating the amine groups within a short time by resistance heating, so that the regeneration of amine groups can be carried out rapidly. Therefore, the cycle of carbon dioxide adsorption and regeneration can be shortened, so the size and weight of the carbon dioxide adsorption apparatus can be reduced even when a large amount of carbon dioxide is treated, making it suitable for installation in an aircraft. Furthermore, because the strength of the carbon dioxide adsorption element is increased by the electric resistance element, the element is easy to handle and degradation caused by vibrations or the like can be prevented. When the electric resistance element is sandwiched by sandwiching sections made from aluminum or aluminum alloy, the amine groups can be uniformly heated and the degradation of amine groups caused by excess heating or insufficient regeneration thereof caused by insufficient heating can be prevented because aluminum or aluminum alloy has excellent thermal conductivity.

The carbon dioxide adsorption apparatus in accordance with the present invention comprises a carbon dioxide adsorption element for adsorbing carbon dioxide contained in air and a coil for generating alternating magnetic flux, in which the carbon dioxide adsorption element comprises a support member, a porous film covering the support member, and amine groups clinging to the inner surface of each pore of the film for carbon dioxide adsorption, wherein the support member includes an element that is heated by electric energy, and carbon dioxide adsorbed by the amine groups is released by heating the element. In this case, it is preferable that the element is an electrically conductive element that has electrical conductivity and is disposed in the position through which the magnetic flux generated by the coil passes, and carbon dioxide adsorbed by the amine groups is released by induction heating of the electrically conductive element.

As a result, the temperature of the electrically conductive element rises to the temperature suitable for regenerating the amine groups within a short time by induction heating, so that the regeneration of amine groups can be carried out rapidly. Therefore, the cycle of carbon dioxide adsorption and regeneration can be shortened, so the size and weight of the carbon dioxide adsorption apparatus can be reduced even when a large amount of carbon dioxide is treated, making it suitable for installation in an aircraft. Furthermore, because the strength of the carbon dioxide adsorption element is increased by the electrically conductive element, the element is easy to handle and degradation caused by vibrations or the like can be prevented. When the electrically conductive element is made from aluminum or aluminum alloy, the amine groups can be uniformly heated and the degradation of amine groups caused by excess heating or insufficient regeneration thereof caused by insufficient heating can be prevented because aluminum or aluminum alloy has excellent thermal conductivity.

When the support member has an electric resistance element or electrically conductive element, it is preferable that a temperature detection unit of the carbon dioxide adsorption element and a controller for controlling power supply to the electric resistance element or coil for generating magnetic flux based on the detected temperature are provided. Furthermore, when the electric resistance element is resistance heated or when the electrically conductive element is induction heated, it is preferable that a heating unit is provided for heating the air for regeneration, which flows in the air flow path configured by the carbon dioxide adsorption element. As a result, temperature fluctuations of the carbon dioxide adsorption element are reduced, the regeneration proceeds gradually, and temperature can be easily controlled within a range in which the amine groups are not degraded.

It is preferable that a large-diameter pore disposed at the surface and a plurality of small-diameter pores opened in the bottom section of the large-diameter pore are provided as each pore formed in the film. Due to the presence of the large-diameter pore, the flow of air along the surface of the carbon dioxide adsorption element can be changed and the introduction of carbon dioxide molecules into the pores surrounded by the amine groups can be enhanced.

It is preferable that the inner diameter of the pore surrounded by the amine groups clinging to the inner surface of each pore of the film is 2 nm to 100 nm. When the inner diameter of the pore surrounded by the amine groups is 2 nm or more, a structure is obtained in which the size of gas molecule is less than that of the pore by an order of magnitude and the gas molecule can easily enter the pore surrounded by the amine groups and exit therefrom, so that the gas molecules can easily enter the pores surrounded by the amine groups at the time of adsorption; when the inner diameter of the pore is 100 nm or less, the gas molecules have plenty opportunities to come into contact with the amine groups, and carbon dioxide can be adsorbed with good efficiency without consuming much energy because a sufficient surface area of the amine groups can be ensured.

When the large-diameter pore and small-diameter pores are provided as each pore formed in the film, the inner diameter of the pore surrounded by the amine groups clinging to the inner surface of the small-diameter pore can be 2 nm to 100 nm, and the inner diameter of the pore surrounded by the amine groups clinging to the inner surface of the large-diameter pore can be more than 100 nm. It is preferable that the inner diameter of the pore surrounded by the amine groups clinging to the inner surface of the small-diameter pore is set to a value suitable for adsorption, because the amine groups clinging to the inner surface of the small-diameter pores take a large portion of the surface area of the carbon dioxide adsorption element.

With the carbon dioxide adsorption element and carbon dioxide adsorption apparatus in accordance with the present invention, a large amount of carbon dioxide can be rapidly adsorbed, and the amine groups for carbon dioxide adsorption can be rapidly and uniformly regenerated with high-temperature air; and the carbon dioxide adsorption element in accordance with the present invention can be provided by using the method in accordance with the present invention.

Explanation Of Reference Numeral

211a,311aelectric resistance element

313power supply unit

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1illustrates an embodiment in which a carbon dioxide adsorption apparatus100using the carbon dioxide adsorption element in accordance with the present invention is employed in an air conditioning device1for an aircraft. In the air conditioning device1for an aircraft, the air extracted from an engine1is cooled with a heat exchanger called a precooler2, and the air flow rate is controlled with a flow rate control valve39, the degree of opening of which is designated by signals from a controller (not shown in the figure). The air extracted from the engine, flow rate of which is controlled by the flow rate control valve39, is almost adiabatically compressed with a radial compressor3. The air whose temperature is increased due to compression with the radial compressor3is cooled by external air passing through a ram air flow paths9in a main cooler4and a regenerative heat exchanger4a, and guided into a water separator7for trapping water. When the aircraft is on the ground and the engine1is stopped, the air compressed with a high-pressure air supply unit1′ is used for air conditioning instead of the air extracted from the engine1.

The air from which water is separated in the water separator7is guided to an air flow path75. Part of the air flowing through the air flow path75is guided in an air separation unit16. A selective permeability membrane16aconstituting the air separation unit16has a permeability of oxygen present in the air higher than a permeability of nitrogen. A selective permeability membrane with a permeability of oxygen lower than a permeability of nitrogen also can be used. As a result, the air introduced into the air separation unit16is separated into a nitrogen-enriched gas and an oxygen-concentrated air. The nitrogen-enriched gas is introduced into a fuel surrounding region15via a first control valve41aand released to an external space14through a release path. The oxygen-concentrated air can be released to the external space14via a second control valve41band can be introduced into a cabin8via a third control valve41c. The opening degree of each of control valves41a,41b,41cis adjusted by signals from the controller, and the flow rate of air passing through the air separation unit16can be adjusted by the adjustment of the opening degree.

The remaining part of air introduced into the air flow path75is almost adiabatically expanded in an expansion turbine5, thereby producing a cooling air. A cooling device of air cycle type is thus constituted by the compressor3and expansion turbine5. The cooling air produced by the cooling device of air cycle type is introduced into a cabin8including a cockpit space of the aircraft from the regenerative heat exchanger4avia a mixing chamber13. The expansion work of the expansion turbine5is transferred via a shaft6to the compressor3and thus used as a compression power. A motor6afor additionally providing a power necessary for driving the compressor3is mounted on the shaft6connecting the compressor3with the turbine5.

A bypass air flow path11is provided for introducing the air extracted from the engine1into the cabin8without passing through the cooling device of air cycle type. The bypass air flow path11is opened and closed by a hot air modulation valve12, degree of opening of which can be adjusted by signals from the controller. When the hot air modulation valve12is opened, part of the extracted air is introduced from the bypass air flow path11into the cabin8via the mixing chamber13without cooling in the cooling device of air cycle type constituted by the compressor3and expansion turbine5.

The air inside the cabin8flows into an outflow air flow path40in an amount obtained by deducting the amount of fuselage leak air and released air from the air flow path to the outside of the aircraft from the amount of supplied air from the air conditioning device, and dust and odor are removed with a filter42in the outflow air flow path40. Part of the air flowing into the outflow air flow path40is guided into the mixing chamber13via a fan F1.

Part of the air flowing out of the cabin8via the outflow air flow path40is guided with a fan F2into a first auxiliary air flow path71branching from the outflow air flow path40, and then heated with a second regenerative heat exchanger72.

Moisture adsorption sections83are connected to the outflow air flow path40and first auxiliary air flow path71via an air flow path switching mechanism50. Thus, as shown inFIG. 2, a large number of moisture adsorption sections83are provided like a honeycomb structure inside a rotary drum80, and the longitudinal direction thereof is along the rotation axis direction. Adsorbing agent is included in each moisture adsorption section83. The adsorbing agent constituting each moisture adsorption section83adsorb moisture contained in the air and release the adsorbed moisture when the temperature rises above that at the time of the adsorption process, and can be comprise of substance adsorbing water molecules, such as silica gel. Separators81are joined to both end surfaces of the rotary drum80rotatably via sealing members (omitted in the figure). Each separator81is constructed by connecting an outer ring81aand an inner ring81bwith two arms81c, and fixed to the fuselage of the aircraft. A central shaft80aof the rotary drum80is rotatably supported via a bearing (omitted in the figure) by the inner ring81bof each separator81. A motor82is connected to the central shaft80a, and the rotary drum80is rotated when the motor82is driven by signals from the controller25. The space between the outer ring81aand inner ring81bin each separator81is separated into two regions81d,81eby two arms81c. One region81din each separator81is connected to the first auxiliary air flow path71via a piping joint84, and the other region81eis connected to the outflow air flow path40via a piping joint85. As a result, when the rotary drum80is rotated by the control of the air flow path switching mechanism50with the controller25, each moisture adsorption section83is switched between a state of connection to the first auxiliary air flow path71and a state of connection to the outflow air flow path40.

Owing to heating with second regenerative heat exchanger72, the temperature of air flowing through the first auxiliary air flow path71becomes higher than that of the air inside the cabin8, for example, 80° C.-120° C. On the other hand, the temperature of air guided from the cabin8into the outflow air flow path40becomes, for example, 20° C.-30° C. As a result, because the moisture adsorption sections83becomes a low temperature when the air introduced from the cabin8via the outflow air flow path40flows therethrough, the adsorbing agent adsorbs water molecules contained in the air flowing out of the cabin8. On the other hand, because the moisture adsorption sections83becomes a high temperature when the air introduced via the first auxiliary air flow path71flows therethrough, the adsorbing agent is regenerated by the release of the adsorbed water molecules into the air introduced via the first auxiliary air flow path71. For example, when the adsorbing agent is silica gel, water molecules are adsorbed in an amount of 0.25 kg or more by 1.0 kg of silica gel at a temperature of 20° C., but only not more than 0.02 kg of water molecules are adsorbed by 1.0 kg of silica gel at a temperature of 100° C. Therefore, after the water molecules contained in the air released from the cabin8have been adsorbed by the adsorbing agent, the water molecules are released into the air flowing through the first auxiliary air flow path71. Moreover, the adsorbing agent is regenerated so as to be reused.

The air flowing through the first auxiliary air flow path71is guided into a third switching valve27after passing through the moisture adsorbing sections83. The third switching valve27can switch the air flow path by signals from the controller between a state in which the air introduced thereinto is released into the space14outside the aircraft and a state in which the air is introduced into the cabin8via the mixing chamber13. A unit is thereby constituted, in which the air flowing through the first auxiliary air flow path71can be introduced into the cabin8after passing through the moisture adsorbing section83and the moisture adsorbed by the moisture adsorbing sections83is introduced into the cabin8.

The outflow air flow path40is branched into a second auxiliary air flow path95and third auxiliary air flow path96at downstream area of the moisture adsorbing units83. The second auxiliary air flow path95is connected to a compressor17that is driven by a high-frequency motor18as air compression means, and part of the air from which the moisture has been adsorbed by the moisture adsorbing sections83is almost adiabatically compressed. The air whose temperature is increased to about 150° C.-200° C. by being pressurized with the compressor17is subjected to heat exchange with the air flowing through the first auxiliary air flow path71in the second regenerative heat exchanger72, and cooled with the external air passing through the ram air flow path9in a radiator19, whereby it is cooled to a temperature close to normal temperature; this air is thereafter introduced into the carbon dioxide adsorption apparatus100, where carbon dioxide contained therein is adsorbed and removed. The air from which the carbon dioxide has been removed is mixed with the air extracted from the engine and introduced into a radial compressor3via a fourth switching valve36. Because gas containing a very small amount of amine groups can be mixed with the air in the carbon dioxide adsorption apparatus under a certain operation condition, it is preferred that an easy adsorption filter103using active carbon or the like is installed before the fourth switching valve36. On the other hand, part of the air flowing through the first auxiliary air flow path71is heated in the second regenerative heat exchanger72, and then introduced into the carbon dioxide adsorption apparatus100via a branch flow path71aso as to be used therein as high-temperature air for regeneration. The third auxiliary air flow path96is connected to the outflow valve90bvia a switching valve90a. The switching valve90ais switched between a state in which the outflow valve90bis connected to the third auxiliary air flow path96and a state where the outflow valve90bis connected to the cabin8. The opening degree of the outflow valve90bis controlled by the controller based on the pressure inside the cabin8and aircraft altitude respectively detected with sensors not shown in the figures, and the pressure inside the cabin8is appropriately maintained.

As shown inFIG. 3, the carbon dioxide adsorption apparatus100has a plurality of adsorber containers101. The inlet port101aand outlet port101bof each adsorber container101can be selectively connected to the branch flow path71aof the first auxiliary air flow path71and to the second auxiliary air flow path95via respective electromagnetic switching valve102a,102b. As a result, the adsorber containers101can be selectively connected to the branch flow path71aand second auxiliary air flow path95by control of the electromagnetic switching valve102a,102bby the controller25.

A carbon dioxide adsorption element110is accommodated in each adsorber container101. As shown inFIG. 4, the carbon dioxide adsorption element110in the present embodiment has a shape of a radiation fin, and, as shown inFIG. 5A, comprises a foil-like support member111made from aluminum or aluminum alloy, porous aluminum oxide (Al2O3) films112formed by oxidation of the surface layers of the support member111, and amine groups113clinging to the inner surface of each pore112aof the films112. The amine groups113adsorb carbon dioxide molecules contained in the air, and release the adsorbed carbon dioxide molecules when the temperature rises above that at the time of the adsorption process. The depth direction of each pore112aof the films112is the thickness direction (direction of arrow A inFIG. 5A) of the support member111. The inner diameter D of pore surrounded by the amine groups113clinging to the inner surface of each pore112aof the films112is 2 nm to 100 nm. The aluminum oxide films112are formed on the surface layers of the support member111, as shown inFIG. 5B, by using the support member111as an anode and passing an electric current through an acidic treatment liquid, and thus the films grow in the direction shown by an arrow in the figure. In other words, because the films112grow in the thickness direction of the support member111, the depth direction of each pore112aof the films112becomes the thickness direction of the support member111. The forming of such anodization films112can be carried out by a known process. The films112of uniform quality having pores112asuitable for adhesion of the amine groups113can be formed by controlling the parameters such as type, concentration, and temperature of the electrolyte133and the applied electric current. In particular, the thickness (“t” in the figure) of the oxidation layer that constitutes the film112is determined by the type of the treatment liquid used and the voltage applied during the treatment, and the thickness of the oxidation layer generally decreases with the decrease in the voltage. It is preferred that acid whose principal ingredient is dilute sulfuric acid or the like is used for the treatment liquid to form the pores with the above-described inner diameter D according to the present invention. After the growth of the films112has been completed as shown inFIG. 5C, the surface layers most often have honeycomb structure, in which the grown portions from adjacent regions of the films112are densely distributed. It goes without saying that the openings of pores112aare not closed.

As shown in the first modification example shown inFIG. 6AandFIG. 6B, the thickness of the aluminum oxidation layers, that is, the thickness of the films112is changed by decreasing the treatment voltage in the process of forming the films112. As a result, the pores formed in the films112can be grown as large-diameter pores112bat the surface and a plurality of small-diameter pores112aopened in the bottom section of the large-diameter pore112b. In this case, because the amine groups113clinging to the inner surface of the small-diameter pores112atake a large portion of the surface area of the carbon dioxide adsorption element110, it is preferred that the inner diameter D of the pore surrounded by the amine groups113clinging to the inner surface of the small-diameter pore112ais 2 nm to 100 nm, this range being suitable for adsorption. The inner diameter of pore surrounded by the amine groups113clinging to the inner surface of the large-diameter pore112bcan exceed 100 nm. The presence of large-diameter pores112bchanges the flow of air along the surface of the carbon dioxide adsorption element110and can enhance the introduction of carbon dioxide molecules into the pores surrounded by the amine groups113.

As shown inFIG. 7, the support member111of the present embodiment is formed by bending an aluminum foil111′ so that a large number of fin sections111aare formed, with a pair of molding dies121alternately reciprocating in the thickness direction of the aluminum foil111′ unreeled from a roll R. As shown by arrows inFIG. 7, the aluminum foil111′ is unreeled from the roll R by the reciprocation of the molding dies121in the unreeling direction of the aluminum foil111′. The thickness of the support members111formed by such a process is preferably about 0.05 mm to 0.1 mm. As shown by the second modification example illustrated byFIG. 8, a reinforcing material120in the shape of a thin sheet made from aluminum or aluminum alloy and having a thickness slightly larger than that of the support member111can be mounted on the support member111. The reinforcing member120is unreeled from a roll R′ via a roller124, positioned in the location of bonding to the support member111after powdered solder123has been sprayed thereon with a nozzle122, and attached to the support member111by melting the solder123with a heating device125. The thickness of the reinforcing member120is, for example, about 0.3 mm. In order to prevent aluminum or aluminum alloy constituting the support member111from oxidizing during melting of the solder123, it is preferred that a sealing wall127surrounding the heating zone of the support member111that is heated with the heating device125is provided and that the heating zone is covered with a cooling gas atmosphere produced by supplying inert gas126such as argon. No specific limitation is placed on the shape of the support member111, provided that it is suitable for operation.

The aluminum oxide films112of the present embodiment are formed by conducting anodization treatment of the support member111after the fin sections111ahave been formed. The thickness of the film112is preferably from several microns to several tens of microns. To be more precise, as shown inFIG. 9, the support member111is fed by a rotary roller131into an electrolyte133such as sulfuric acid in a container132, a power source134is connected to the support member111and container132by using the support member111as an anode, the surface layers of the support member111are oxidized by supplying electric power from the power source134, and the porous aluminum oxide films112are formed.

The process of forming a large number of fin sections and the anodization treatment process can be carried out not only in the above-described order but also in the reversed order.

In the present embodiment, the support member111having the films112formed on the surface thereof is accommodated in a container135as shown inFIG. 11, after being wound like a roll as shown inFIG. 10. A solution obtained by dissolving polymer agent such as polyethylene imine, which has a large number of amine groups113, into a volatile solvent is poured into the container135, and the support member111having the films112formed thereon is completely immersed into the solution. The container135is then closed and degassed with a vacuum pump or the like. As a result, the air remaining inside the pores112aof the films112is sucked in, so that the solution instead of the air is introduced into the pores112aby pressurization or the like, and the amine groups113cling to the inner surface of each pore112aby drying the solution. The roll-shaped carbon dioxide adsorption element110formed in the above-described manner is accommodated in the adsorber container101as shown inFIG. 12. The adsorber container101has a tubular shape, and the air inlet port101aand outlet port101bare provided at respective ends thereof By setting the axial direction of the adsorber container101parallel to the surface of the support member111, the air inside the adsorber container101flows along the surface of the support member111.

When the inlet port101aand outlet port101bof the adsorber container101are connected to the second auxiliary air flow path95, the temperature of air flowing in the adsorber container101is normal temperature because it is cooled at upstream area; therefore, carbon dioxide contained in the air is adsorbed by amine groups113. When the inlet port101aand outlet port101bof the adsorber container101are connected to the branch flow path71aof the first auxiliary air flow path, the temperature of air flowing in the adsorber container101rises to about 80° C.-120° C. as described above; therefore, carbon dioxide adsorbed by the amine groups113is released and the amine groups113are regenerated so as to be reused.

The air flowing out of the outlet port101bof the adsorber container101through the second auxiliary air flow path95is guided into a fourth switching valve36. The fourth switching valve36can switch the air flow path by signals from the controller between a state in which the introduced air is introduced into the cabin8via the mixing chamber13and a state in which the air is introduced into the cooling device of air cycle type. As a result, the air flowing out of the cabin8is again introduced into the cabin8via the fourth switching flow valve36after the carbon dioxide in the air has been reduced.

The air containing a large amount of carbon dioxide that flows out of the outlet port101bof the adsorber container101through the branch flow path71aof the first auxiliary air flow path is discharged into the space14outside the aircraft via a pressure reduction valve91g′. At this time, the amount of discharged air can be controlled in the pressure reduction valve91g′ by signals from the controller25.

According to the above-described embodiment, when the air flowing out of the cabin8is again introduced into the cabin8, carbon dioxide contained in the air is discharged to the outside of the aircraft via the carbon dioxide adsorption element110, and the carbon dioxide in the air inside the aircraft can be reduced. At this time, because the foil-like support member111is thin, the resistance to the flow of air can be reduced and the adsorption of carbon dioxide contained in the air can be performed rapidly without increasing the pressure loss in the air flow path constituted by the carbon dioxide adsorption element110, by causing the air to flow along the surface of the support member111in the air flow path. Furthermore, because the amine groups113can adsorb carbon dioxide contained in the air and can release the adsorbed carbon dioxide when the temperature rises above that at the time of adsorption process, the amine groups113can be regenerated by causing the high-temperature air to flow in the air flow path. Because the support member111is made from aluminum or aluminum alloy with excellent thermal conductivity, even if it is heated locally, the heat is diffused and degradation due to increase in temperature is prevented; therefore, it is heated so that a uniform temperature distribution is achieved and the amine groups113can be heated uniformly and rapidly to a temperature suitable for regeneration by the heat of the high-temperature air. Furthermore, because the support member111is thin and light weight, the carbon dioxide adsorption element110is reduced in size and weight; moreover, the structure thereof is simplified and it can function normally even in an environment where it is subjected to shaking, vibrations, and acceleration. Furthermore, when the inner diameter of pore surrounded by the amine groups113clinging to the inner surface of the pore112aof the aluminum oxide film112on the surface of the support member111is made 2 nm or more, gas molecules can easily enter the pore, and when the inner diameter is 100 nm or less, a sufficient surface area of amine groups113can be ensured and carbon dioxide can be adsorbed with good efficiency without consuming much energy. Furthermore, the air inside the aircraft compressed by the compressor17can be effectively used as high-temperature air for regenerating the amine groups113. Therefore, an excellent carbon dioxide adsorption apparatus100for improving the air inside the cabin8of the aircraft accommodating a large number of passengers can be realized. As a result, the amount of fresh air that is taken in from outside the aircraft in flight can be reduced, so that energy consumed to compress the fresh air can be reduced.

The shape of the carbon dioxide adsorption element110in use is not limited to a roll. For example, as shown in the third modification example inFIG. 13andFIG. 14, a plurality of carbon dioxide adsorption elements110having a large number of fin sections111acan be stacked via reinforcing members120and accommodated inside the adsorber container101.

As shown in the fourth modification example inFIG. 15andFIG. 16, portions111a′ shifted in the direction perpendicular to the air flow direction (the direction of arrow F shown inFIG. 15, the direction F is perpendicular to the paper sheet inFIG. 16) can be formed in the respective fin sections111aof the carbon dioxide adsorption element110at intervals in the air flow direction so that the contact probability between the air and amine groups113is increased.

The carbon dioxide adsorption apparatus100can also employ a configuration corresponding to that of the moisture adsorbing device as shown inFIG. 2rather than that comprised of the split containers as shown inFIG. 3. In this case, a roll-shaped carbon dioxide adsorption element110similar to that of the above-described embodiment is used as shown in the fifth modification example inFIG. 17instead of the moisture adsorption sections83, in which the high-temperature air is introduced from the branch flow path71aof the first auxiliary air flow path71into the region81d, and the air flowing out of the cabin8is introduced into the region81evia the outflow air flow path40.

The carbon dioxide adsorption element110of the sixth modification example is shown inFIG. 18. In the carbon dioxide adsorption element110of the present modification example, a bendable plate-like support member211is provided instead of the foil-like support member111of the above-described embodiment. The support member211is covered with porous aluminum oxide films112similar to those of the above-described embodiment. The support member211has an electric resistance element211acomprised of a metal mesh having electrical conductivity as an element that is heated by electric energy, insulator211bcovering the electric resistance element211a, and sandwiching sections211cfor sandwiching the electric resistance element211avia the insulator211b. The sandwiching sections211cof the present modification examples are comprised of aluminum or aluminum alloy foils. Metal having comparatively high electric resistance is preferably used as material for the electric resistance element211a; for example, a stainless steel comprising a large amount of Ni and Cr can be used. Ceramic such as silicon dioxide or silicon carbide can be used as material for the insulator211b. The sandwiching sections211care integrated with the insulator211bvia adhesive211d. The porous aluminum oxide films112similar to those of the above-described embodiment are formed by anodic oxidation of aluminum or aluminum alloy of the surface layers of the sandwiching sections211c. The amine groups113cling to the inner surface of each pore112aof the films112. The size of each pore112acan be the same as in the above-described embodiment. Furthermore, large-diameter pores112band small-diameter pores112acan be provided in the same manner as in the first modification example.

FIG. 19illustrates a process of forming the carbon dioxide adsorption element110of the sixth modification example. The electric resistance element211aunreeled from a roll is introduced into a vacuum container221, and the insulator211bis evaporated on the electric resistance element211ainside the vacuum container221, then the adhesive211dis sprayed from a sprayer222onto the insulator211b, the sandwiching sections211cunreeled from rolls are bonded to both surfaces of the insulator211bvia the adhesive211d, and the adhesive211dis cured by heating with the heating rollers223, thereby the plate-like support member211is formed. The support member211is then introduced into an electrolyte133such as sulfuric acid in the container132via a guide rollers in the same manner as in the above-described embodiment, and the surface layers of the support member211are subjected to anodic oxidation, thereby the porous aluminum oxide films112covering the support member211are formed. The support member211covered with the films112is then introduced via a guide rollers into solution227comprising amine groups in a container226, the amine groups113cling to the inner surface of each pore112aof the films112, and a long plate-like carbon dioxide adsorption element110manufactured in this manner is dried with the heater228. End sections of the electric resistance element211aare exposed at both ends of the carbon dioxide adsorption element110for the below-described connection to the electrodes231,232.

A carbon dioxide adsorption apparatus100using the carbon dioxide adsorption element110of the sixth modification example is shown inFIG. 20. The adsorption apparatus100comprises a tubular adsorber container101accommodating the carbon dioxide adsorption element110. Similarly to the above-described embodiment, the inlet port101aat one end and the outlet port101bat the other end of the adsorber container101can be selectively connected to the branch flow path71aof the first auxiliary air flow path71and the second auxiliary air flow path95via the respective electromagnetic switching valves102a,102b. Inside the adsorber container101, the carbon dioxide adsorption element110is bent along the axial direction of the adsorber container101at plural sections, and the air inside the adsorber container101flows along the surface of the support member211. An electrode231connected to one end of the electric resistance element211aand an electrode232connected to the other end thereof are mounted on the adsorber container101. The electric resistance element211ais connected via the two electrodes231,232to a power supply unit233for resistance heating. Furthermore, a temperature detection unit234for detecting the surface temperature of the carbon dioxide adsorption element110is mounted on the adsorber container101, the temperature measurement signal obtained with the temperature detection unit234is converted with the operation circuit235into a digital signal, and transmitted to the controller25connected to the power supply unit233. For example, a non-contact type sensor for measuring the quantity of infrared rays radiation or a contact type resistance thermometer can be used as the temperature detection unit234. The controller25controls the power supply unit233by ON/OFF control, current quantity control or the like based on the measured temperature, and the power supplied to the electric resistance element211ais thereby controlled. Other aspects of this modification example are identical to those of the above-described embodiment, and the identical components are assigned with identical symbols.

When the inlet port101aand outlet port101bof the adsorber container101are connected to the second auxiliary air flow path95, carbon dioxide contained in the air is adsorbed by the amine groups113similarly to the above-described embodiment, because the temperature of air flowing in the adsorber container101becomes almost the normal temperature. When the inlet port101aand outlet port101bof the adsorber container101are connected to the branch flow path71aof the first auxiliary air flow path, carbon dioxide adsorbed by the amine groups113is released due to resistance heating of the electric resistance element211ato which power is supplied from the power supply unit233. The air containing the released carbon dioxide is discharged to the space14outside the aircraft via the pressure reducing valve91g′.

As shown in the seventh modification example inFIG. 21, the insulator211bcan be previously attached on the surface of the electric resistance element211aby thermal spraying or the like, and the sandwiching sections211ccan be integrated by using another means such as soldering instead of the adhesive211dso that the previously integrated electric resistance element211aand insulator211bare sandwiched.

FIG. 22shows the carbon dioxide adsorption element110of the eighth modification example. The carbon dioxide adsorption element110of the present modification example comprises a bendable thin plate-like support member311instead of the foil-like support member111of the above-described embodiment. The support member311is covered with porous aluminum oxide films112similar to those of the above-described embodiment. The support member311has an electric resistance element311acomprised of a thin plate having electrical conductivity and has sandwiching sections311bmade from aluminum or aluminum alloy for sandwiching the electric resistance element311a. The material of the electric resistance element311ais identical to that of the electric resistance element211aof the sixth modification example. The sandwiching sections311bare integrated with the surface of the electric resistance element311aby vapor deposition, hot-dip coating or the like. Porous aluminum oxide films112similar to those of the above-described embodiment are formed by anodization of aluminum or aluminum alloy of almost the entire region of the sandwiching sections311b. Amine groups113cling to the inner surface of each pore112aof the films112. The dimensions of each pore112acan be identical to those of the above-described embodiment. Furthermore, similarly to the first modification example, large-diameter pores112band small-diameter pores112acan be provided.

FIG. 23illustrates a process of forming the carbon dioxide adsorption element110of the eighth modification example. The electric resistance element311aunreeled from the roll is introduced into a vacuum container321, and the sandwiching sections311bare formed by performing vapor deposition of aluminum or aluminum alloy on the electric resistance element311ainside the vacuum container321, thereby a plate-like support member311is formed. The support member311is then introduced into the electrolyte133such as sulfuric acid in the container132via guide rollers in the same manner as in the above-described embodiment, the surface layers of the support member311are subjected to anodic oxidation, and thus the porous aluminum oxide films112covering the support member311are formed. In the present modification example, the aluminum oxide films112function as insulator. Then, the support member211covered with the films112is introduced via guide rollers into solution227comprising amine groups in a container226similar to that of the sixth modification example, the amine groups113cling to the inner surface of each pore112aof the films112, and a long plate-like carbon dioxide adsorption element110manufactured in this manner is dried with the heater228. End sections of the electric resistance element311aare exposed at both ends of the carbon dioxide adsorption element110for connection to the electrodes231,232in the same manner as in the sixth modification example. The carbon dioxide adsorption element110of the eighth modification example can be used in the same manner as the carbon dioxide adsorption element110of the sixth modification example in the same carbon dioxide adsorption apparatus100. Other aspects of this modification example are identical to those of the above-described embodiment, and the identical components are assigned with identical symbols.

The plate-like carbon dioxide adsorption element110of the ninth modification example shown inFIG. 24has an annular shape. As shown inFIG. 25, in the carbon dioxide adsorption element110of the present modification example, a bendable thin plate-like support member411is provided instead of the foil-like support member111of the above-described embodiment. The support member411is covered with porous aluminum oxide films112similar to those of the above-described embodiment. The support member411has an electrically conductive element411acomprised of a thin plate having electrical conductivity as an element to be heated by electric energy, and sandwiching sections411bmade from aluminum or aluminum alloy for sandwiching the electrically conductive element411a. No specific limitation is placed on the material of the electrically conductive element411a, provided that it can generate heat by induction heating; in the present modification example, this material is stainless steel. The sandwiching sections411bare integrated with the surface of the electrically conductive element411aby vapor deposition. Porous aluminum oxide films112similar to those of the above-described embodiment are formed by anodization of aluminum or aluminum alloy of almost the entire region of the sandwiching sections411b. Amine groups113cling to the inner surface of each pore112aof the films112. The dimensions of each pore112acan be identical to those of the above-described embodiment. Furthermore, similarly to the first modification example, large-diameter pores112band small-diameter pores112acan be provided. The carbon dioxide adsorption element110of the present modification example can be manufactured by being formed into a shape of long plate in the same manner as in the eighth modification example and then by being blanked with a press in an annular shape. Because the electrically conductive element411aonly have to generate heat by induction heating, it can be made from aluminum or aluminum alloy if the frequency of the induction magnetic field is set high. In this case, because the porous aluminum oxide films112similar to those of the above-described embodiment can be obtained by anodizing the surface layers of the electrically conductive element411a, the sandwiching sections411bbecome unnecessary.

A carbon dioxide adsorption apparatus100using the carbon dioxide adsorption element110of the ninth modification example is shown inFIG. 26. The adsorption apparatus100comprises a tubular adsorber container101accommodating the carbon dioxide adsorption element110; the inlet port101aat one end and the outlet port101bat the other end of the adsorber container101can be selectively connected to the branch flow path71aof the first auxiliary air flow path71and the second auxiliary air flow path95via the respective electromagnetic switching valves102a,102b.

A plurality of carbon dioxide adsorption elements110are stacked with a certain spacing therebetween in the adsorber container101. When the carbon dioxide adsorption elements110are stacked, gaps constituting air flow paths between the surfaces of the stacked carbon dioxide adsorption elements110can be ensured by forming a large number of protrusions projecting from the surfaces of the carbon dioxide adsorption elements110or by inserting spacers such as three-dimensional meshes. A large number of protrusions projecting from the surfaces of the carbon dioxide adsorption elements110can be formed by providing peaks and valleys on the support member411by pressing or the like prior to forming the films112. An air introducing tube101ccommunicating with the inlet port101aand an air discharge tube101dcommunicating with the outlet port101bare fixed to the adsorber container101. The stacked carbon dioxide adsorption elements110are sandwiched between a flange101c′ provided on the outer periphery of the air introducing tube101cand a flange101d′ provided on the outer periphery of the air discharging tube101d. Furthermore, the stacked carbon dioxide adsorption elements110are divided by a partition plate101ein two sides: an air introduction side and an air discharge side. The partition plate101eallows magnetic flux to pass therethrough and regulates the flow of air through the central holes of the carbon dioxide adsorption elements110. The air introducing tube101cis inserted into the central hole of each carbon dioxide adsorption element110on the air introduction side, and the part of the air introducing tube101cinserted into the central holes is porous. The air discharging tube101dis inserted into the central hole of each carbon dioxide adsorption element110on the air discharge side, and the part of the air discharging tube101dinserted into the central holes is porous.

The air introduced into the adsorber container101from the inlet port101avia the air introducing tube101cflows from the central holes of carbon dioxide adsorption elements110on the air introduction side into the gaps between the carbon dioxide adsorption elements110via the pores of the air introducing tube101c, and flows toward the peripheral wall of the adsorber container101along the surfaces of the support members411, and then flows along the peripheral wall of the adsorber container101; as a result, the air reaches the outer periphery of each carbon dioxide adsorption element110on the air discharge side, and then flows from the outer periphery of each carbon dioxide adsorption element110on the air discharge side into the gaps between the carbon dioxide adsorption elements110, and flows toward the central holes of the carbon dioxide adsorption elements110along the surfaces of the support members411, so that it reaches the central holes of the carbon dioxide adsorption elements110via the pores of the air discharging tube101d, and thereafter the air is discharged from the outlet port101bvia the air discharging tube101d.

A coil431for generating alternating magnetic flux is embedded in the peripheral wall of the adsorber container101. The coil431is connected to a high-frequency power source432and generates a high-frequency alternating magnetic flux shown by a dot-dash line m1when a high-frequency alternating current is applied thereto. The frequency of the alternating current generated by the high-frequency power source432is set to several tens of kilohertz. A conductive wire constituting the coil431is preferably composed of a large number of fine wires, and the high-frequency alternating current flows through the surface of each wire. A magnetic material for leading the magnetic flux passing through the carbon dioxide adsorption elements110is preferably disposed outside the peripheral wall of the adsorber container101. A ferrite, in which generation of eddy current is low level, is preferred as the magnetic material. The electrically conductive element411aof each support member411is disposed in the passage position of the magnetic flux generated by the coil431, so that the magnetic flux passes through along the thickness direction of the electrically conductive element411a.

A temperature detection unit234identical to that of the sixth modification example is mounted on the adsorber container101to detect the surface temperature of the carbon dioxide adsorption elements110. The temperature measurement signal detected by the temperature detection unit234is converted into a digital signal by an operation circuit235and transmitted to the controller25, and the alternating power source432is connected to the controller25. The controller25controls the alternating power source432by ON/OFF control, current quantity control or the like based on the measured temperature, and the power supplied to the coil431is thereby controlled. Other aspects of this modification example are identical to those of the above-described embodiment, and the identical components are assigned with identical symbols.

When the inlet port101aand outlet port101bof the adsorber container101are connected to the second auxiliary air flow path95, carbon dioxide contained in the air is adsorbed by the amine groups113similarly to the above-described embodiment, because the temperature of air flowing in the adsorber container101becomes almost the normal temperature. When the inlet port101aand outlet port101bof the adsorber container101are connected to the branch flow path71aof the first auxiliary air flow path, the electrically conductive element411ais induction heated by eddy current because the high-frequency alternating magnetic flux is generated by the coil431. Carbon dioxide adsorbed by the amine groups113is released due to the induction heating of the electrically conductive element411a. The air containing the released carbon dioxide is discharged to the space14outside the aircraft via the pressure reducing valve91g′. In the present modification example, the adsorption surface area of the carbon dioxide adsorption elements110is small in the vicinity of the central holes and large in the vicinity of the outer periphery thereof. Accordingly, when the adsorption saturation zone gradually increases from the upstream side of the air flow to the downstream side; in other words, when the adsorption saturation advances, this advance is accelerated at the final stage. Furthermore, when the carbon dioxide is released from the carbon dioxide adsorption elements110, the advance of carbon dioxide release is also accelerated at the final stage. Therefore, the advancement of carbon dioxide adsorption and release can be easily controlled.

According to the carbon dioxide adsorption elements110of the sixth to ninth modification examples, the temperature of the electric resistance elements211a,311aand the temperature of the electrically conductive element411aare risen to the temperature suitable for regenerating the amine groups113within a short period by resistance heating and induction heating, respectively. As a result, the regeneration of amine groups113can be carried out rapidly; therefore, the cycle of carbon dioxide adsorption and regeneration can be shortened and the number of adsorption and regeneration cycles per unit time can be increased. As a result, even when a large amount of carbon dioxide is treated, the size and weight of the carbon dioxide adsorption apparatus100can be reduced, making it suitable for installation at the aircraft. Because the amount of heat generated by the electric resistance elements211a,311aand electrically conductive element411ais controlled with the controller25, the surface temperature of the carbon dioxide adsorption element110can be maintained at a level suitable for regenerating the amine groups113. In this case, because the temperature of air flowing inside the adsorber container101is risen to a temperature suitable for regenerating the amine groups113, which is about 80° C.-120° C. as shown in the above-described embodiment, temperature fluctuations of the carbon dioxide adsorption element110are reduced. As a result, the temperature control for performing sufficient regeneration can be easily conducted with preventing the carbon dioxide adsorption element110from degradation. Furthermore, because the strength of the carbon dioxide adsorption element110is increased by the electric resistance elements211a,311aor electrically conductive element411a, the element110is easy to handle and degradation caused by vibrations or the like can be prevented. When the electric resistance elements211a,311aor electrically conductive element411ais sandwiched by sandwiching sections211c,311bmade from aluminum or aluminum alloy, because aluminum or aluminum alloy has excellent thermal conductivity, the amine groups113can be uniformly heated. As a result, the degradation of amine groups113caused by excess heating or insufficient regeneration thereof caused by insufficient heating can be prevented. The electric resistance elements211a,311aor electrically conductive element411aitself can be made from aluminum or aluminum alloy; in this case, the electric resistance elements211a,311aor electrically conductive element411ais preferably made thin to increase the electric resistance thereof.

In the carbon dioxide adsorption apparatus100using the carbon dioxide adsorption element110of the sixth to ninth modification examples, a plurality of adsorber containers101can be used. In this case, carbon dioxide can be adsorbed by carbon dioxide adsorption elements110in some adsorber containers101, whereas the carbon dioxide adsorption elements110in the remaining adsorber containers101can be regenerated. Furthermore, when the amount of carbon dioxide that has to be removed is small, the carbon dioxide adsorption elements110in some adsorber containers101can be in a standby mode. Furthermore, it is preferred that the pressure of air introduced into the adsorber container101is set lower when carbon dioxide is adsorbed than when the amine groups113are regenerated so as to be close to the pressure outside the aircraft. As a result, the release of carbon dioxide from the amine groups113can be enhanced.

The present invention is not limited to the above-described embodiment and modification examples. For example, the carbon dioxide adsorption elements can be formed to have a shape of cone, semispherical or cup, and stacked via gaps. Furthermore, an aircraft air conditioner can be used for conditioning the external air compressed by an electric motor rather than the air extracted from the engine. Moreover, the carbon dioxide adsorption element can be used for adsorbing carbon dioxide contained in the air in the space other than that in the aircraft.