humidifier

Abstract

Humidifier (10) with a housing (14) extending along an axial direction (12), wherein the housing (14) has a first inlet (16), a first outlet (18), a second inlet (20) and a second outlet (22), and wherein a membrane unit (40) is arranged inside the housing (14), wherein the first inlet (16) and the first outlet (18) are flow-connected to each other by means of a first flow path (1') and wherein the second inlet (20) and the second outlet (22) are flow-connected to each other by means of a second flow path (2'), wherein the membrane unit (40) is cylindrical and has a plurality of hollow fiber membranes arranged side by side, wherein the membrane unit (40) is surrounded at least partially to the outside by a first chamber (42), wherein the first chamber (42) is surrounded at least partially to the outside by a second chamber (44) separate from the first chamber (42). is,wherein the first chamber (42) and the second chamber (44) are flow-connected to each other by one or more throttle slots (48), characterized in that the membrane unit (40) has a section with membrane potting (50, 52) at each of its axial ends and the first chamber (42) has a greater length along the axial direction (12) than the second chamber (44), wherein the first chamber (42) extends along the membrane unit (40) from the section with membrane potting (50) at the first axial end to the section with membrane potting (52) at the second axial end.

Description

[0001] The invention relates to a humidifier having features of the preamble of claim 1.

[0002] Humidifiers of the type mentioned above are known from the prior art, e.g., from DE 10 2014 104 960 A1. The fuel cell humidifier described therein has a folded diffusion medium that separates a first flow area (moist side) from a second flow area (dry side). This allows water to be transferred from a first gas (moist side) to a second gas (dry side), thereby increasing the relative humidity of the second gas. However, the production of the folded diffusion medium is comparatively complex. Furthermore, in addition to fluid dynamic problems caused by multiple deflections of the gas flows, which can lead to a corresponding pressure drop, this design also results in a comparatively large space requirement.

[0003] US 2008 / 0237902 A1 discloses a humidifier with features of the preamble of claim 1.

[0004] The invention is based on the objective of providing a humidifier with simple design means that has a comparatively compact structure and is advantageous in terms of fluid dynamics.

[0005] The invention solves this problem by means of a humidifier with the features of claim 1.

[0006] The humidifier is designed to humidify a gas stream. It is therefore capable of transferring moisture or water from a (comparatively moist) gas stream (second flow path) to a (comparatively dry) gas stream (first flow path). In a specific embodiment, the humidifier can optionally be configured as a humidifier for a fuel cell (fuel cell humidifier).

[0007] The humidifier has a housing extending along an axial direction with a first inlet, a first outlet, a second inlet, and a second outlet. A membrane unit is arranged inside the housing. The first inlet and the first outlet are connected to each other via a first flow path (gas to be humidified or gas stream to be humidified). The second inlet and the second outlet are connected to each other via a second flow path (gas to be dehumidified or gas stream to be dehumidified). The membrane unit is cylindrical and comprises a plurality of hollow fiber membranes arranged side by side. The membrane unit is surrounded (radially) to the outside, at least partially, by a first chamber. The first chamber is, in turn, surrounded (radially) to the outside, at least partially, by a second chamber, separate from the first chamber.The first chamber and the second chamber are connected to each other by one or more throttle slots.

[0008] The proposed design allows for improved airflow through the membrane unit via the second flow path, ensuring that humid air (the gas or gas stream to be dehumidified, e.g., humid air from the stack of a fuel cell) passes through the hollow fibers as uniformly as possible along their length. For this purpose, two chambers are arranged on the outside of the membrane unit, connected by one or more throttle slots. The first (inner) chamber (inner exhaust duct) creates a uniform resistance around the membrane unit due to the throttle slot(s). This results in a very uniform flow from the center outwards. After passing through the throttle slot(s), the air flows into the second (outer) chamber (outer exhaust duct), which acts as an air collector and directs the exhaust air to the second outlet.

[0009] The first inlet and the first outlet are connected by the first flow path (first flow connection). The first flow path extends from the first inlet along or parallel to the axial direction through the membrane unit to the first outlet. In other words, the gas stream to be humidified (e.g., dry, oxygenated or oxygen-rich fresh air) passes through the membrane unit along or parallel to the axial direction. At the first outlet, the gas stream (humidified by passing through the membrane unit) leaves the humidifier (humidified fresh air). This gas stream can then be fed, for example, to a fuel cell stack.

[0010] The second inlet and the second outlet are connected via the second flow path (second flow connection). This second flow path extends from the second inlet through the membrane unit to the second outlet. Specifically, the second flow path enters the interior of the membrane unit via a pipe section, which will be described later, and from there flows (radially) outwards to the first chamber and the second chamber, ultimately reaching the second outlet. In other words, the gas flow to be dehumidified (e.g., moist, oxygen-depleted air) passes a short distance along or parallel to the axial direction of the membrane unit. Within the membrane unit, the gas flow then flows (radially) outwards (through the first and second chambers) to the second outlet. At the second outlet, the gas flow (dehumidified by passing through the membrane unit) exits the humidifier (dehumidified or used air).The humid, oxygen-depleted air at the second inlet can, for example, be supplied as exhaust air from a fuel cell stack. The dehumidified air at the second outlet can, for example, be supplied to a compressor.

[0011] According to the invention, the membrane unit has a section with membrane potting at each of its axial (aligned along the axial direction) ends. In the section with membrane potting, the spaces between the hollow fiber membranes are sealed, so that a gas or a moist gas stream can only flow axially through the hollow fiber membranes themselves. Flow through (non-existent) spaces between the hollow fiber membranes is not possible in the sections with membrane potting.

[0012] Between the sections with encapsulated membranes, the hollow fiber membranes are arranged side by side, with the central longitudinal axis of each hollow fiber membrane being arranged, in particular, parallel to the axial direction of the housing. The spaces between the hollow fiber membranes are preferably free, so that a gas or a moist gas stream can flow past the hollow fiber membranes and, for example, reach the second outlet (radially) to the outside.

[0013] The wall of the hollow fiber membrane is permeable to water vapor, which thus passes through the membrane wall into the interior. In this way, water vapor or moisture is transferred from the second flow path or gas stream (from outside the hollow fiber membrane) to the first flow path or gas stream (inside the hollow fiber membrane). This increases the relative humidity of the first gas stream.

[0014] The membrane unit can have a casing or outer shell, e.g., made of plastic, which surrounds the membrane unit radially. In the area of ​​the hollow fiber membrane (axially between the sections with membrane potting), the casing has numerous openings through which gas or a moist gas stream from the interior of the membrane unit can enter the first chamber. These openings extend uniformly around the circumference of the cylindrical casing. The openings can be designed as elongated slots or as individual passages, e.g., bores.

[0015] The edging preferably extends axially over the sections with membrane potting and the intervening section with (free) hollow fiber membranes. The edging holds the components of the membrane unit together and may each have a fixing that engages in the sections with membrane potting.

[0016] In the area of ​​the sections with membrane potting, the encasement can each have a sealing section, preferably circumferential, for sealing the membrane unit relative to the housing. The sealing section can have a groove, preferably also circumferential, for receiving an elastic sealing element, in particular an O-ring. The membrane unit can, in particular, be designed as a cartridge unit.

[0017] The first and second chambers can be separated from each other by a wall extending, in particular, parallel to the axial direction. Regardless of this, the second (outer) chamber is fluidically connected, in particular, to the second outlet.

[0018] According to the invention, the first (inner) chamber has a greater length along the axial direction than the second (outer) chamber. The first (inner) chamber can also have a lower height along a radial direction oriented orthogonally to the axial direction than the second (outer) chamber. These measures promote the formation of a uniform resistance around the membrane unit. This contributes to a balanced and high transfer of moisture from the second flow path or gas stream to the first flow path or gas stream.

[0019] Specifically, the first chamber extends along the membrane unit from the section with membrane potting at the first end to the section with membrane potting at the second end. The second chamber can extend along the axial direction only over a portion of the first chamber, for example, at least predominantly or completely within a housing section, such as a second housing half.

[0020] Advantageously, the first (inner) chamber and / or the second (outer) chamber can be configured at least predominantly circumferentially along the circumference of the membrane unit (at least 50% circumferential), and preferably completely circumferentially. This contributes to a high efficiency of the membrane unit. Specifically, the first chamber and / or the second chamber can each be configured as an annular space.

[0021] Advantageously, a water outlet (exhaust air membrane unit) can be formed on the housing, particularly along the downward direction of gravity, which is connected to the second (outer) chamber via a flow path. This allows excess moisture or water to be collected and drained from the humidifier or its housing.

[0022] In a preferred embodiment, the throttle slot(s) can be formed at least predominantly (at least 50%), preferably completely, circumferentially. This contributes to comparatively homogeneous flow conditions around the membrane unit. Specifically, the throttle slot can be designed as a continuous throttle slot along the circumferential direction. It is also conceivable that the throttle slot is designed as several slots spaced apart along the circumferential direction with intermediate web sections (similar to a dashed line). Alternatively or additionally, the throttle slot(s) can have a different slot width along the circumferential direction (dimension of the throttle slot(s) along or parallel to the axial direction).Depending on the prevailing flow conditions and / or the influence of gravity, this allows for adjustments to be made to ensure the most uniform flow possible.

[0023] Advantageously, the second inlet can be flow-connected to a tube body that extends along or parallel to the axial direction, particularly centrally, through the membrane unit, wherein the tube body (at least in the area where it axially overlaps with the hollow fiber membranes, i.e., between the sections with membrane potting) has a plurality of passages in its tube wall (jacket side), wherein a throttling disc is arranged in the tube body, at which the clear internal cross-section of the tube body is reduced by at least 30%, preferably by at least 40%, and more preferably by at least 50%. The passages in the tube wall allow the passage of gas or moist gas flow from the interior of the tube body into the space between the hollow fiber membranes.The integrated throttle disc (air mass flow throttle) ensures that the majority of the incoming air mass flow does not accumulate at the end of the pipe body furthest from the second inlet. Instead, a large portion of the gas or air flow is directed outwards into the inner chamber (inner exhaust duct) of the cartridge at the end of the pipe body facing the second inlet, on the opposite side from the inlet. This contributes to high efficiency due to a uniformly distributed flow along the axial direction.

[0024] Advantageously, the throttle disc can be positioned axially from the second inlet, slightly ahead of the axial center (center along the axial direction) of the diaphragm unit. In other words, the throttle disc is not located centrally within the diaphragm unit, but rather offset from the center towards the second inlet. This facilitates flow through the diaphragm unit at the end facing the second inlet.

[0025] In a preferred embodiment, the end of the tube body facing away from the second inlet can be closed by an end wall, wherein an opening is formed in the end wall that is flow-connected to a further water outlet (inlet air membrane unit). The end wall can, in particular, be arranged along the axial direction within the section facing away from the second inlet with membrane potting. Since entrained water, which, for example, comes from the stack of a fuel cell, also reduces efficiency because it condenses on the membrane surface and thus prevents the exchange of water vapor in this area, an opening, e.g., a bore, is integrated on the opposite side of the air inlet (second inlet) of the moist air from the stack, at the end of which the water can exit the humidifier. This already separated water no longer needs to be separated downstream of the humidifier by a separate water separator, e.g.,to avoid damaging any existing turbine. This allows the water separator to be smaller or even omitted entirely.

[0026] Advantageously, the first inlet and the second inlet can be arranged in a first section of the housing, and the first outlet and the second outlet can be arranged in a second (further) section of the housing. This allows advantageous flow characteristics of the humidifier to be achieved, particularly in the form of a so-called cross-flow principle.

[0027] The housing can be composed of several housing parts, each of which abuts a parting line in the assembled state. Specifically, the housing parts can be designed as two housing parts that abut each other at a parting line, in particular as two housing halves. A flange connection can be formed at the parting line; that is, each housing part or housing half can have a corresponding flange section at the parting line.

[0028] The housing can be made of metal or plastic. Regardless of the material, reinforcing ribs can be provided on the outside of the housing.

[0029] The invention is explained in more detail below with reference to the figures, where identical or functionally identical elements are provided with identical reference numerals, possibly only once. The figures show: Fig. 1. An embodiment of the humidifier with regard to the inlets ( Fig. 1a) and to the outlets ( Fig. 1b), each in perspective view; Fig. 2 a perspective longitudinal section of the humidifier from Fig. 1; Fig. 3. another longitudinal section of the humidifier Fig. 1 with illustration of the currents; and Fig. 4 a cross-section of the humidifier Fig. 1 along a in Fig. 3. Drawing of the intersection axis IV-IV ( Fig. 4a) and an enlarged section of the longitudinal section from Fig. 3 in the area of ​​the second outlet with illustration of the flow ( Fig. 4b).

[0030] The Fig. 1a and Fig. Figure 1b shows a humidifier, which is generally designated by the reference numeral 10. The humidifier 10 can, for example, be configured and / or intended as a humidifier 10 for a fuel cell.

[0031] The humidifier 10 has a housing 14 extending along an axial direction 12. The housing 14 has a first inlet 16, a first outlet 18, a second inlet 20 and a second outlet 22.

[0032] In the example, the housing 14 has two housing halves 24, 26 which abut each other at a parting line 28. The housing halves 24, 26 each have a flange section 30, 32 at the parting line 28, so that the housing halves 24, 26 can be connected to each other in the example by means of a flange connection. In the example, there are several screw points 34 for this purpose.

[0033] In this example, the first inlet 16 and the second inlet 20 are located at the end of housing half 24 furthest from flange section 30. The first outlet 18 and the second outlet 22 are located on the other housing half 26. The first outlet 18 is located at the end of housing half 26 furthest from flange section 32. The second outlet 22 is located adjacent to flange section 32.

[0034] The second inlet 20 and the first outlet 18 are aligned with the axial direction 12 and the central longitudinal axis 12 of the housing 14, respectively. The first inlet 16 and the second outlet 22 are angled upwards against the direction of gravity g. Independently of this, stiffening ribs 36 and 38 are arranged on housing half 24 and housing half 26, respectively.

[0035] The further design of the humidifier 10 will be described with reference to the Fig. 2 to 4b described.

[0036] Inside the housing 14 a membrane unit 40 is arranged (see Fig. 2 and Fig. 3) In this example, the membrane unit 40 is cylindrical, specifically in the form of a vertical circular cylinder, and comprises a plurality of hollow fiber membranes arranged side by side (not shown individually). The membrane unit 40 is described in more detail below.

[0037] The first inlet 16 and the first outlet 18 are connected by means of a first flow path 1' (flow to be humidified; cf. Fig. 3) flow-connected. The second inlet 20 and the second outlet 22 are connected by means of a second flow path 2' (flow to be dehumidified; cf. Fig. 3) interconnected by flow.

[0038] The membrane unit 40 is surrounded radially outwards at least by a first (inner) chamber 42 (inner gas flow exhaust duct), wherein the first chamber 42 is designed circumferentially in the example (cf. Fig. 2 to 4). The first chamber 42 is in turn surrounded radially outwards by a second (outer) chamber 44 separate from the first chamber 42, the second chamber 44 being formed around the perimeter in the example.

[0039] The first chamber 42 and the second chamber 44 are separated from each other by a wall 46 extending parallel to the axial direction 12 in the example and are flow-connected to each other by a throttle slot 48 (cf. Fig. 2 and Fig. 3) In the example, the throttle slot 48 is formed completely circumferentially (not shown). The second chamber 44 is flow-connected to the second outlet 22 (see figure). Fig. 3 and Fig. 4b).

[0040] The membrane unit 40 has at each of its axial (aligned along the axial direction 12) ends a section with membrane potting 50, 52 (see Fig. 2 and Fig. 3) In the sections with membrane potting 50, 52, the spaces between the hollow fiber membranes are sealed, so that a gas or a moist gas stream can only flow axially through the hollow fiber membranes themselves.

[0041] Between the sections with diaphragm potting 50, 52, the hollow fiber diaphragms are arranged side by side (intermediate section 54), with the central longitudinal axis of the hollow fiber diaphragms being arranged parallel to the axial direction 12 of the housing (not shown). The spaces between the hollow fiber diaphragms are free, so that a gas or a moist gas stream can flow past the hollow fiber diaphragms and, for example, reach the second outlet 22 (radially) to the outside.

[0042] The membrane unit 40 has a rim 56 that surrounds the membrane unit 40 radially outwards (cf. Fig. 2 and Fig. 4b). The frame 56 has a plurality of openings 58 in the area of ​​the hollow fiber membrane between the sections with membrane potting 50, 52 (intermediate section 54) through which gas or a moist gas stream from the interior of the membrane unit 40 can enter the first chamber 42. The frame 56 extends axially over the sections with membrane potting 50, 52 and the intermediate section 54. The frame 56 holds the components of the membrane unit 40 together.

[0043] In the area of ​​the sections with membrane potting 50, 52, the edging 56 each has a sealing section 59, 60 extending along the circumferential direction for sealing the membrane unit 40 relative to the housing 14 (see figure). Fig. 2 and Fig. 3) In the example, the sealing section has a circumferential groove 62, 63 for receiving an elastic sealing element, such as an O-ring. The membrane unit 40 is designed as a cartridge unit in the example.

[0044] The first chamber 42 has a greater length along the axial direction 12 than the second chamber 44. The first chamber 42 extends along the membrane unit 40 from the section with membrane potting 50 at the first end to the section with membrane potting 52 at the second end. The first chamber 42 extends into both housing halves 24, 26. The second chamber 44 extends almost entirely only into the housing half 26. The first chamber 42 has a lower height along a radial direction 13 – oriented orthogonally to the axial direction 12 – than the second chamber 44.

[0045] In the example, the first chamber 42 and the second chamber 44 are formed completely around the circumference of the membrane unit 40 (see figure). Fig. 4a). The first chamber 42 and the second chamber 44 are each designed as an annular space. A water outlet 66 is formed on the housing 14 along the downward direction of gravity g, which is flow-connected to the second chamber 44 (see Figure 4a). Fig. 2 and Fig. 3).

[0046] In the example, the throttle slot 48 is formed completely circumferentially along the circumferential direction and has a uniform slot width along the circumferential direction (dimension of the throttle slot 48 along or parallel to the axial direction 12).

[0047] The second inlet 22 is flow-connected to a tube body 68, which extends centrally through the membrane unit 40 along the axial direction 12 (cf. Fig. 2 and Fig. 3) The pipe body 68 has a plurality of passages 70 axially between the sections with membrane potting 50, 52 (intermediate area 54) in its pipe wall (jacket side). The passages 70 allow the passage of gas or moist gas flow from the interior of the pipe body 68 into the space between the hollow fiber membranes of the membrane unit 40.

[0048] A throttle disc 72 is arranged in the pipe body 68, at which the clear inner cross-section of the pipe body 68 is reduced by 50% in the example (see figure). Fig. 2, Fig. 3 and Fig. 4a). The throttle disk 72 is arranged along the axial direction 12, starting from the second inlet 20, and positioned in front of the axial center (center along the axial direction 12) of the diaphragm unit 40. In other words, the throttle disk 72 is not located centrally in the diaphragm unit 40 along the axial direction 12, but rather offset from the center a short distance towards the second inlet 20.

[0049] The end of the tube body 68 facing away from the second inlet 20 is closed by an end wall 74 (cf. Fig. 2 and Fig. 3) An opening 76 is formed in the end wall 74, which is flow-connected to a further water outlet 78. In the example, the end wall 74 is arranged along the axial direction 12 within the section with membrane potting 52 facing away from the second inlet 20.

[0050] The first inlet 16 and the first outlet 18 are flow-connected to each other by means of the first flow path 1' (cf. Fig. 3) The first flow path 1' extends from the first inlet 16 along or parallel to the axial direction 12 through the membrane unit 40 to the first outlet 18. In other words, the gas stream to be humidified (e.g., dry, oxygenated, or oxygen-rich fresh air) passes through the membrane unit 40 along or parallel to the axial direction 12. At the first outlet 18, the gas stream (humidified by passing through the membrane unit 40) leaves the humidifier 10 (humidified fresh air). This gas stream can then be supplied, for example, to a fuel cell stack.

[0051] The second inlet 20 and the second outlet 22 are flow-connected to each other via the second flow path 2' (see figure). Fig. 3, Fig. 4a and Fig.4b). The second flow path 2' extends from the second inlet 20 through the membrane unit 40 to the second outlet 22, whereby the second flow path 2' enters the interior of the membrane unit 40 via the pipe body 68 and from there runs radially outwards to the first chamber 42 and the second chamber 44 to the second outlet 22. In other words, the gas flow to be dehumidified (e.g., moist, oxygen-depleted air) passes through the membrane unit 40 for a short distance along or parallel to the axial direction 12, whereby the gas flow within the membrane unit 40 then flows (radially) outwards (via the first chamber and the second chamber) to the second outlet 22.

[0052] At the second outlet 22, the gas stream (dehumidified by passing through the membrane unit 40) leaves the humidifier 10 (dehumidified or used air). The moist, oxygen-depleted air at the second inlet 20 can, for example, be supplied as used air from a fuel cell stack. The dehumidified air at the second outlet 22 can, for example, be supplied to a compressor.

Claims

[1] Humidifier (10) with a housing (14) extending along an axial direction (12), wherein the housing (14) has a first inlet (16), a first outlet (18), a second inlet (20) and a second outlet (22), and wherein a membrane unit (40) is arranged inside the housing (14), wherein the first inlet (16) and the first outlet (18) are flow-connected to each other by means of a first flow path (1') and wherein the second inlet (20) and the second outlet (22) are flow-connected to each other by means of a second flow path (2'), wherein the membrane unit (40) is cylindrical and has a plurality of hollow fiber membranes arranged side by side, wherein the membrane unit (40) is surrounded at least partially to the outside by a first chamber (42), wherein the first chamber (42) is surrounded at least partially to the outside by a second chamber separate from the first chamber (42). (44) is surroundedwherein the first chamber (42) and the second chamber (44) are flow-connected to each other by one or more throttle slots (48), characterized by , that the membrane unit (40) has a section with membrane potting (50, 52) at each of its axial ends and the first chamber (42) has a greater length along the axial direction (12) than the second chamber (44), wherein the first chamber (42) extends along the membrane unit (40) from the section with membrane potting (50) at the first axial end to the section with membrane potting (52) at the second axial end. [2] Humidifier (10) according to claim 1, characterized by , that the first chamber (42) has a lower height along a radial direction (13) oriented orthogonally to the axial direction (12) than the second chamber (44). [3] Humidifier (10) according to any one of the preceding claims, characterized bythat the first chamber (42) and / or the second chamber (44) are formed at least predominantly circumferentially along the circumferential direction of the membrane unit (40), preferably completely circumferentially along the circumferential direction of the membrane unit (40). [4] Humidifier (10) according to any one of the preceding claims, characterized by , that a water outlet (66) is formed on the housing (14) which is flow-connected to the second chamber (44). [5] Humidifier (10) according to any one of the preceding claims, characterized by that the throttle slot(s) (48) are formed at least predominantly circumferentially along the circumferential direction and / or that the throttle slot(s) (48) have a different slot width along the circumferential direction. [6] Humidifier (10) according to any one of the preceding claims, characterized by, that the second inlet (20) is flow-connected to a tube body (68) which extends along or parallel to the axial direction (12), in particular centrally, through the membrane unit (40), wherein the tube body (68) has a plurality of passages (70) in its tube wall, wherein a throttle disk (72) is arranged in the tube body (68) at which the clear inner cross-section of the tube body (68) is reduced by at least 30%, preferably by at least 40%, further preferably by at least 50%. [7] Humidifier (10) according to the preceding claim, characterized by , that the throttle disk (72) is arranged along the axial direction (12) starting from the second inlet (20) along the axial direction (12) before the axial center of the diaphragm unit (40). [8] Humidifier (10) according to claim 6 or 7, characterized by, that the end of the pipe body (68) facing away from the second inlet (20) is closed by an end wall (74), wherein an opening (76) is formed in the end wall (74) which is connected to a further water outlet (78) by flow. [9] Humidifier (10) according to any one of the preceding claims, characterized by , that the first inlet (16) and the second inlet (20) are arranged in a first section (24) of the housing (14) and the first outlet (18) and the second outlet (22) are arranged in a second section (26) of the housing (14).

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