JP2007144278A - Deodorizer, and air conditioner equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a deodorizer capable of enhancing decomposition and removal efficiencies of odorous gas components or toxic volatile chemical substances in air by a small amount of a noble metal-based catalyst and charged electric power, and cleaning the air more inexpensively with lower energy. <P>SOLUTION: This device is provided with a discharge electrode 1 applied with a high voltage and a grounding electrode 4 disposed in a flow space of treating object fluid; and a catalyst part 2 disposed between the discharge electrode 1 and grounding electrode 4 and cleaning the odorous gas components and toxic volatile chemical substances. The catalyst part 2 carries a mixture formed by mixing one or more kinds of porous adsorbent having mesopores or micropores, such as zeolite, activated carbon or silica gel; a porous metal oxide having fine pore structure consisting of mainly transit metal, such as manganese oxide or titanium oxide; and noble metals like platinum or palladium. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a deodorizing device that removes odorous gas components and harmful volatile chemical substances in the air and cleans the air, and an air conditioner equipped with the same.

A conventional deodorizing apparatus includes discharge means for generating low-temperature plasma by discharge in a flow space of a fluid to be treated, and catalyst means disposed in the discharge field of the discharge means or downstream of the discharge field, and the catalyst means Consists of a plasma catalytic reactor containing a noble metal catalyst (see, for example, Patent Document 1).

JP 2002-336645 A (page 4-5, FIG. 1)

In conventional deodorization equipment, if the precious metal catalyst contained in the catalyst means is not used in a large amount in the plasma catalyst reactor, the decomposition and removal efficiency of odorous gas components and harmful volatile chemicals will be low. There was a problem that it would be expensive to use. In addition, there is a problem that the efficiency of decomposition / removal of odorous gas components and harmful volatile chemicals is low with respect to the electric power supplied for discharge in the plasma catalytic reactor.

The present invention has been made to solve the above-described problems, and can improve the decomposition and removal efficiency of odorous gas components and harmful volatile chemical substances in the air with a small amount of noble metal catalyst and input power. It is possible to obtain a deodorizing apparatus capable of purifying air at a lower cost and with lower energy and an air conditioner equipped with the same.

A deodorizing apparatus according to the present invention is disposed in a circulation space of a fluid to be treated, and purifies a discharge electrode to which a high voltage is applied and its counter electrode, and an odorous gas component and a harmful volatile chemical substance in the fluid to be treated. In the deodorization apparatus including a catalyst part, the catalyst part is disposed between the discharge electrode and the counter electrode, and carries a mixture of an adsorbent, a metal oxide, and a noble metal.

  In the deodorizing apparatus according to the present invention, the catalyst part is disposed between the discharge electrode and the counter electrode, and adsorbent, metal oxide, and noble metal are mixed and supported, so that the adsorption action on the catalyst, the metal oxide, and By combining the oxidation action and decomposition action by precious metals and the decomposition action by radical generation of discharge, synergistic effect is created, improving the decomposition and removal efficiency of odorous gas components and harmful volatile chemical substances at low cost and low energy, Indoor air can be cleaned.

Embodiment 1 FIG.
1 is an exploded perspective view of a deodorizing apparatus according to Embodiment 1 for carrying out the present invention.
In FIG. 1, the deodorizing device 6 is made of a metal such as stainless steel or copper, and is made of a flat plate-shaped discharge electrode 1 having a sharp tip and a plurality of protrusions, a catalyst portion 2, and an insulator such as plastic, A casing 3 that houses the discharge electrode 1 and the catalyst unit 2 and supports the front surface of the deodorizing device 6, and a ground electrode (a counter electrode of the discharge electrode 1) made of a conductive material such as metal or conductive plastic and having an opening such as a mesh ) 4 and a support cover 5 that supports the casing 3 and the ground electrode 4 to support the entire deodorizing device 6.
In addition, the deodorizing apparatus 6 is arrange | positioned on a ventilation path so that it may become a leeward side from a windward side in order of the casing 3, the discharge electrode 1, the catalyst part 2, the ground electrode 4, and the support cover 5. FIG.

Here, the catalyst part 2 has, for example, a honeycomb-like, corrugated-, or square-shaped opening parallel to the air flow in the ventilation path on a base material such as paper ceramic or cordierite, and zeolite, activated carbon, silica gel 1 each of a porous adsorbent having mesopores or micropores such as a porous metal oxide having a pore structure centered on a transition metal such as manganese oxide or titanium oxide, and a noble metal such as platinum or palladium. More than one kind is mixed and supported on the base material, and is further configured to come into contact with the ground electrode 4. Therefore, the catalyst portion 2 is a mixture of an insulating material and a conductive material in which a porous adsorbent, a porous metal oxide, and a noble metal are supported on a base material. Since the catalyst portion 2 has some conductivity, it is in contact with the ground electrode 4. As a result, it becomes the same potential as the ground electrode 4.

Further, the opening of the ground electrode 4 is formed to be larger than the opening of the catalyst unit 2. Further, a high voltage power source (not shown) is connected to the discharge electrode 1 and the ground electrode 4, and a positive or negative DC high voltage of 3.5 kV to 10 kV is applied between them.

Next, the operation will be described.
First, corona discharge is generated from the discharge electrode 1 to the catalyst unit 2 by a DC voltage supplied between the discharge electrode 1 and the ground electrode 4 from a high-voltage power supply (not shown). At this time, odorous gas components and volatile organic compounds in the air sucked from the casing 3 such as acetaldehyde and formaldehyde are once captured by the adsorbing portion of the hydrophobic zeolite, manganese oxide and the like on the catalyst portion 2, and the corona It is decomposed and rendered harmless by active species such as oxygen radicals and hydroxyl radicals generated by discharge, and dissociates from the adsorption part.

Here, the corona discharge works preferentially on the noble metal on the catalyst portion 2, and the noble metal also works to assist decomposition by the corona discharge. In particular, among noble metals, platinum and palladium have a strong affinity for oxygen and have a property of adsorbing many oxygen atoms. That is, the noble metal is activated by corona discharge, the dissociation of the adsorbed oxygen on the noble metal is promoted, and the adsorption / desorption rate of oxygen atoms is promoted. Oxygen atoms dissociated from noble metals are mainly trapped in the odorous gas components and volatile organic compounds trapped in the porous adsorbent adsorbent at high concentrations, and mainly in the porous metal oxide adsorbers at low concentrations. The odor gas components and volatile organic compounds are decomposed and dissociated by an oxidation reaction. For this reason, the improvement in the adsorption / desorption rate directly leads to the improvement in the decomposition rate.

In addition, oxygen atoms dissociated from precious metals oxidize odor gas components and volatile organic compound decomposition products decomposed by corona discharge, thereby recombining odor gas components and volatile organic compound decomposition products. Since it can also be prevented, the decomposition of odorous gas components and volatile organic compounds is further promoted.

Further, in the catalyst part, each component of the porous adsorbent, the porous metal oxide, and the noble metal supported (attached) on the catalyst part 2 is high so that the discharge energy is uniformly applied to the surface of the catalyst part 2. It is desirable that they are mixed in a dispersed state. Furthermore, it is desirable that the porous adsorbent, the porous metal oxide particles, and the noble metal particles are in contact with each other.
In addition, the porous adsorbent and the porous metal oxide to be supported are porous bodies having mesopores or micropores in order to enhance the adsorption performance of the odor gas and harmful volatile chemical substances onto the catalyst part 2. desirable.

Next, a verification experiment using an experimental product of the deodorizing apparatus will be described.
FIG. 2 is an exploded perspective view of an experimental product of the deodorizing apparatus showing Embodiment 1 of the present invention, and FIG. 3 is a diagram showing the acetaldehyde decomposition / removal performance of the experimental product of the deodorizing apparatus.
In FIG. 2, an experimental product 11 of a deodorizing apparatus is made of a metal such as stainless steel or copper, and includes a discharge electrode 1 having two needle-like protrusions, a porous adsorbent on a substrate having a honeycomb-like opening, A catalyst cover 2 supporting a porous metal oxide and a noble metal; a center cover 8 that covers the discharge electrode 1 and the catalyst part 2 and is made of an insulating material such as plastic and provided with a hole 8a for an air passage; The front cover 9 is disposed upstream of the air passage 8 and holds the discharge electrode 1 and is provided with a hole 9a for the air passage. The front cover 9 is made of a conductive material such as metal, precious metal, or conductive plastic, and has an opening such as a mesh. And a rear cover 10 that holds the ground electrode 4 and is provided with an air passage hole 10a. A DC voltage is applied between the discharge electrode 1 and the ground electrode 4 to perform corona discharge.

FIG. 3 is a diagram showing the relationship between the input power and the acetaldehyde removal rate in the experimental product of the deodorizing apparatus showing Embodiment 1 of the present invention, and only palladium (2 g / l) as an adduct is attached to the catalyst unit 2 (FIG. 3). A), hydrophobic zeolite + manganese oxide (same B), platinum (2 g / l) only (same C), hydrophobic zeolite + manganese oxide + platinum (0.025 g / l) (same D), hydrophobic zeolite The state of acetaldehyde removal when a voltage is applied using + manganese oxide + palladium (0.5 g / l) (same E) is shown.

According to FIG. 3, with palladium (2 g / l) alone, the acetaldehyde removal rate gradually increases as the input power increases, but reaches the upper limit in the vicinity of 25%. Further, with only platinum (2 g / l), even if the input power is increased, the acetaldehyde removal rate is almost constant at about 15%, and the removal rate remains low.
Therefore, in the case of, for example, hydrophobic zeolite + manganese oxide + platinum (0.025 g / l) mixed with zeolite and manganese oxide with less precious metal, the acetaldehyde removal rate increases as the input power increases. When the input power is 0.2 W, the acetaldehyde removal rate is about 38%, and the acetaldehyde removal rate is improved as compared with the case of only platinum (2 g / l). Further, even in the case of hydrophobic zeolite + manganese oxide + palladium (0.5 g / l), the acetaldehyde removal rate increases as the input power increases, and at an input power of 0.2 W, the acetaldehyde removal rate becomes about 42%. The acetaldehyde removal rate is improved as compared with 2 g / l) alone, and a high acetaldehyde removal effect can be obtained with less input power as compared with the case of hydrophobic zeolite + manganese oxide.

Next, a countermeasure for ozone generated when removing acetaldehyde in the experimental product 11 of the deodorizing apparatus will be described. FIG. 4 is a diagram showing the relationship between the input power and the amount of ozone generated in the experimental product of the deodorization apparatus showing Embodiment 1 of the present invention. In the figure, only palladium (2 g / l) is attached to the catalyst unit 2 as an adduct ( 4A), hydrophobic zeolite + manganese oxide (same B), platinum (2 g / l) only (same C), hydrophobic zeolite + manganese oxide + platinum (0.025 g / l) (same D), hydrophobic Shows the case of using the active zeolite + manganese oxide + palladium (0.5 g / l) (same E).

Since ozone affects the human body and has strong odor, it is desirable to suppress the generation amount to 1.0 mg / h or less, and it is necessary to reduce the ozone generation amount per input power. Therefore, according to FIG. 4, when hydrophobic zeolite + manganese oxide + platinum or palladium is attached to the catalyst part 2 (D and E in FIG. 4), the amount of ozone generated per input electric power becomes the smallest, and the input It can be seen that the ozone generation amount can be suppressed to 1.0 mg / h or less by setting the power to about 5 W or less.

Therefore, when adsorbent + metal oxide + noble metal is mixed and attached to the catalyst part, the amount of ozone generated per input power is suppressed compared to the case of adsorbing only precious metal or adsorbent + metal oxide. Therefore, the input power can be set high, the removal rate of odorous gases and harmful volatile chemicals can be improved, and the ozone generation amount can be reduced to 1.0 mg by reducing the input power to about 5 W or less. / h or less.

The structure of the deodorization apparatus demonstrated above is described as an example, and is not limited to this. For example, the discharge electrode 1 having a protrusion is not limited to this shape, and the same effect can be obtained even if it is a thin plate or wire having no protrusion. Further, the structure of the catalyst portion 2 is not limited to a honeycomb shape, a corrugated shape, or a square shape, but is a glass shape made of glass or ceramic, fibers made of a polymer material, or a ceramic structure having a three-dimensional network structure. The same effect can be obtained even in a structure in which a porous adsorbent, a porous metal oxide, and a mixture of an insulator and a conductive material supporting a noble metal are supported on a substrate. Furthermore, although the corona discharge is described as an example of the discharge means, the present invention is not limited to this. For example, the same effect can be obtained even with creeping discharge, silent discharge, and the like. When creeping discharge or silent discharge is used, it is preferable to provide an electrode structure having a discharge surface covered with a dielectric.

  As described above, the deodorizing apparatus 6 has a pore structure centered on transition metals such as a porous adsorbent having mesopores or micropores such as zeolite, activated carbon and silica gel, manganese oxide, and titanium oxide in the catalyst portion 2. By disposing a porous metal oxide containing platinum, a material that supports and supports a noble metal such as platinum or palladium, adsorption action on the catalyst part 2, oxidation action or decomposition action by the metal oxide / noble metal, discharge radical By combining the decomposition action by generation and creating a synergistic effect, the decomposition and removal efficiency of odorous gas components and harmful volatile chemical substances can be improved at low cost and with low energy, and the indoor air can be purified.

Embodiment 2. FIG.
In the second embodiment, an air conditioner including the deodorizing device 6 shown in the first embodiment will be described.
FIG. 5 is a front view of an air-conditioning apparatus provided with a deodorizing apparatus according to Embodiment 2 for carrying out the present invention, and shows a state in which a front panel is removed for convenience. FIG. 6 is a side cross-sectional view of an air conditioner equipped with this deodorizing device. In FIG. 6, the deodorizing apparatus 6 is attached to the ventilation path inlet of the air conditioning apparatus 12, for example, the front surface of the heat exchanger 13 on the upper right side toward the front. As a result, when the air conditioner 12 is in operation, the fan 14 is operated, the indoor air is taken into the deodorizer 6 from above the front of the air conditioner 12, cleaned by the deodorizer 6, and then heated or cooled by the heat exchanger 13. Then, the air conditioner 12 is sent into the room from the front lower side.

FIG. 7 is a perspective view of the catalyst unit of the deodorizing apparatus according to the second embodiment for carrying out the present invention. Since the configuration other than the catalyst unit of the deodorizing apparatus is the same as that of the first embodiment, the illustration is omitted. FIG. 8 is a diagram showing the relationship between the number of cells per square inch and the pressure loss in the catalyst portion of this deodorizing apparatus, and FIG. 9 is a diagram showing the relationship between the number of cells in the catalyst portion of this deodorizing apparatus and the acetaldehyde removal rate. .
Here, in the catalyst part 2 of the deodorizing apparatus 6, a ceramic paper base material having corrugated openings of 200 to 500 cells per square inch is used, and adsorbent, metal oxide, and noble metal are attached to this base material. . Thereby, the improvement of the removal rate of the odorous gas component and volatile organic compound in the air can be expected.

Next, operation | movement of the deodorizing apparatus of an air conditioning apparatus is demonstrated.
First, when the deodorizing device 6 is provided at the inlet of the air passage of the air conditioner 12 and odor components are removed, the catalyst portion 2 has a honeycomb, corrugated or square opening as a more effective structure. Examples include structure or fiber shape. In particular, when a corrugated catalyst as shown in FIG. 7 is used, since the pressure loss during ventilation is low and the circulation is good, the collision probability of the odor component to the catalyst is high and the adsorption performance is excellent.

FIG. 8 shows the cell number dependence of the pressure loss at a flow rate of 1 m / s when the catalyst part 2 having a thickness of 10 mm is used in the ventilation direction. The pressure loss increases in a quadratic function as the number of cells increases. I understand that Therefore, the air conditioner 12 needs to use a corrugated catalyst having a smaller number of cells. In particular, since the pressure loss of 500 cells or less is a value lower than 15 Pa, which has a great influence on the outside air suction in the air conditioner 12, it is necessary to use a catalyst having a corrugated structure of 500 cells or less for the outside air suction. Less significant and desirable.

Furthermore, FIG. 9 shows the cell number dependence of the acetaldehyde removal efficiency in the catalyst part 2 having a corrugated structure provided in the air conditioner 12, and the effect of the catalyst is high between 200 and 500 cells. Can be fully demonstrated, and the adsorption / decomposition effect is the highest.
In addition, although it demonstrated centering on the catalyst part 2 which has a corrugated opening part, the same effect is acquired even if it is a structure and fiber shape which have a honeycomb-shaped and square-shaped opening part.

From the above, deodorization in the air conditioner 12 is achieved by using the catalyst part 2 having corrugated, honeycomb, or square openings between 200 to 500 cells or using the fiber-shaped catalyst part 2. The device 6 can realize the optimum operation, and the decomposition / oxidation reaction by the noble metal and the decomposition by the discharge of the adsorbed component on the catalyst are activated, and the decomposition / removal effect of the deodorizing device 6 can be maximized. is there.
In addition, by providing a deodorizing device at the air passage inlet of the air conditioner, it is possible to heat or cool the air that has been purified by decomposing and removing odorous gas components and harmful volatile chemical substances, and performing comfortable air conditioning. it can.

Embodiment 3 FIG.
In the third embodiment, a description will be given of a case where the material of the discharge electrode of the deodorizing apparatus 6 shown in the first embodiment is changed from a metal such as stainless steel or copper to a noble metal.
FIG. 10 is a diagram showing the relationship between the material of the discharge electrode of the deodorizing apparatus and the acetaldehyde residual rate in Embodiment 3 for carrying out the present invention. In addition, since the structure of the deodorizing apparatus 6 is the same as that of FIG.1 and FIG.2, and only the materials of the discharge electrode 1 differ, illustration is abbreviate | omitted and FIG.1 and FIG.2 are diverted.

Next, the operation will be described with reference to FIG.
In the deodorizing device 6, a discharge electrode 1 formed using one or more kinds of noble metals such as platinum, palladium, rhodium, ruthenium, iridium, gold, silver, or the discharge electrode 1 coated (coated) with the noble metal component is used. As a result, in the first half of the ventilation path in the deodorizing device 6, adsorption / removal of odor components by the noble metal component on the discharge electrode 1 activated by applying a high voltage to the discharge electrode 1 by a high voltage power source (not shown). Oxidation decomposition is performed, and ozone generation is promoted by dissociation of oxygen atoms from the noble metal. Furthermore, discharge radicals (oxygen radicals, hydroxyl radicals, etc.) generated by corona discharge decompose odor components and harmful volatile chemical substances, and subsequent recombination is suppressed by oxygen atoms dissociated from noble metals. The decomposition removal rate of the odor components in the electrode 1 and the discharge is improved. Therefore, the concentration of the odorous component flowing through the ventilation path is reduced, the adsorption amount of the catalyst unit 2 is reduced, and the adsorption removal / decomposition reaction of the odorous component is also efficiently performed, so that the removal rate of the deodorizing apparatus 6 as a whole is large. improves.

Next, a verification experiment using the experimental product 11 of the deodorizing apparatus will be described with reference to FIGS.
FIG. 10 shows the change over time in the residual acetaldehyde ratio due to the difference in the material of the discharge electrode 1 when a constant concentration of acetaldehyde is allowed to flow through the experimental product 11 of the deodorization apparatus. Therefore, in the experimental product 11 of the deodorizing apparatus of FIG. 2, when the discharge electrode 1 is made of stainless steel and platinum and a certain concentration of odor components is circulated through the ventilation path, the acetaldehyde adsorption removal / decomposition rate is high immediately after the start and the residual rate However, since a constant concentration of acetaldehyde always flows in, the amount of adsorption gradually decreases with the passage of time, and the residual ratio of acetaldehyde increases. When a predetermined time elapses, the acetaldehyde adsorption rate on the catalyst unit 2 and the decomposition rate on the catalyst unit 2 due to corona discharge reach an equilibrium, and the change in the remaining rate is reduced.

Therefore, when the residual rate of acetaldehyde is compared between the case where stainless steel is used for the discharge electrode 1 and the case where platinum is used, the residual rate of acetaldehyde is always lower when using platinum than stainless steel. It can be seen that the odor component removal at the electrode 1 is performed by platinum, and the decomposition / removal efficiency of the odor component and the life of the catalyst unit 2 are improved.
In addition, although what formed the discharge electrode 1 using platinum was demonstrated, it formed using 1 or more types of noble metals, such as platinum, palladium, rhodium, ruthenium, iridium, gold | metal | money, silver, or the said noble metal component was coated. The same effect can be obtained.
Moreover, it cannot be overemphasized that the deodorizing apparatus 6 which has the discharge electrode 1 of this embodiment may be provided in the ventilation path entrance of an air conditioning apparatus.

From the above, the discharge electrode 1 is formed by using one or more kinds of noble metals such as platinum, palladium, rhodium, ruthenium, iridium, gold and silver, or by coating the noble metal component. In addition, the decomposition and removal rate of odorous components inside the discharge is improved, the concentration of odorous components flowing through the ventilation path is reduced, the amount of adsorption of the catalyst unit 2 is reduced, and the odorous component removal and decomposition reaction is also efficient. The removal rate of the entire deodorizing device 6 can be greatly improved.

It is a disassembled perspective view of the deodorizing apparatus which shows Embodiment 1 of this invention. It is a disassembled perspective view of the experimental product of the deodorizing apparatus which shows Embodiment 1 of this invention. It is a figure which shows the relationship between the input electric power and the acetaldehyde removal rate in the experimental product of the deodorizing apparatus which shows Embodiment 1 of this invention. It is a figure which shows the relationship between the input electric power and ozone generation amount in the experimental product of the deodorizing apparatus which shows Embodiment 1 of this invention. It is a front view of the air conditioning apparatus provided with the deodorizing apparatus which shows Embodiment 2 of this invention. It is side surface sectional drawing of the air conditioning apparatus provided with the deodorizing apparatus which shows Embodiment 2 of this invention. It is a perspective view of the catalyst part of the deodorizing apparatus which shows Embodiment 2 of this invention. It is a figure which shows the relationship between the cell number per square inch in the catalyst part of the deodorizing apparatus which shows Embodiment 2 of this invention, and a pressure loss. It is a figure which shows the relationship between the number of cells in the catalyst part of the deodorizing apparatus which shows Embodiment 2 of this invention, and acetaldehyde removal efficiency. It is a figure which shows the relationship between the material of the discharge electrode of the deodorizing apparatus which shows Embodiment 3 of this invention, and an acetaldehyde residual rate.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Discharge electrode, 2 Catalyst part, 3 Casing, 4 Ground electrode, 5 Support cover, 6 Deodorizer, 8 Center cover, 9 Front cover, 10 Rear cover, 11 Deodorizer experimental product, 12 Air conditioner, 13 Heat exchange 14 fans.

Claims (13)

A deodorizing apparatus including a discharge electrode and a counter electrode to which a high voltage is applied and a catalyst unit for purifying odorous gas components and harmful volatile chemical substances in the fluid to be treated, which are disposed in the flow space of the fluid to be treated. The deodorizing apparatus according to claim 1, wherein the catalyst unit is disposed between the discharge electrode and the counter electrode, and adsorbent, metal oxide, and noble metal are mixed and supported. The deodorizing apparatus according to claim 1, wherein the noble metal supported on the catalyst portion is platinum and / or palladium. The deodorizing apparatus according to claim 1, wherein the adsorbent supported on the catalyst part is a porous material having a pore structure. The deodorizing apparatus according to claim 1 or 3, wherein the adsorbent supported on the catalyst part has a mesopore or micropore structure. The deodorizing apparatus according to any one of claims 1, 3, and 4, wherein the adsorbent supported on the catalyst part is made of at least one of zeolite, activated carbon, and silica. The deodorizing apparatus according to claim 1, wherein the metal oxide supported on the catalyst is a porous material having a pore structure. The deodorizing apparatus according to claim 1 or 6, wherein the metal oxide supported on the catalyst is a transition metal oxide. The deodorizing apparatus according to claim 1, wherein an electric power applied to the discharge electrode and the counter electrode is 5 W or less. The deodorizing apparatus according to claim 1, wherein the catalyst portion has a honeycomb shape, a corrugated shape, a shape having a square opening, or a fiber shape. The deodorizing apparatus according to claim 1 or 9, wherein the catalyst unit has an opening of 200 to 500 cells per square inch. The deodorizing apparatus according to claim 1, wherein the discharge electrode is formed of a noble metal or is covered with a noble metal. The deodorizing apparatus according to claim 1 or 11, wherein the noble metal on which the discharge electrode is formed or the noble metal to be coated is at least one of platinum, palladium, rhodium, ruthenium, iridium, gold, and silver. An air-conditioning apparatus comprising the deodorizing apparatus according to any one of claims 1 to 12 at an inlet of a ventilation path.

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