Membrane element for a humidifier and humidifier

Abstract

To provide an improved membrane element for a humidifier of a fuel cell system.SOLUTION: The membrane element 10 of the humidifier 100 comprises a membrane media bellows 12 comprising a zig-zag pleated, moisture permeable but gas impermeable membrane media, wherein the membrane media bellows extends at least partially circumferentially about a longitudinal axis 14, wherein the membrane media bellows further comprises pleats 16 extending substantially parallel to the longitudinal axis, wherein the membrane media bellows further has inner pleat folds 20 at an inner circumference 18 and outer pleat folds 24 at an outer circumference, a support 40 having a hollow body and an outer wall arranged at the inner circumference of the membrane media bellows, and a bypass valve 30 integrated into the support, wherein the bypass valve is for selectively blocking and releasing a fluid passage 38 through the support.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The embodiments relate to a membrane element for a humidifier, in particular a membrane element for a humidifier of a fuel cell system, and a humidifier for a fuel cell system.

[0002] This application claims the benefit of European Application No. 24187336.3, filed July 9, 2024, the entire disclosure of which is incorporated herein by reference for all purposes. [Background technology]

[0003] Humidifiers known in the prior art are used, for example, to humidify the process gas of fuel cells that use hydrogen and / or molecular oxygen or air to generate electricity. To this end, the process gas supplied to the fuel cell is typically set to a desired, stable humidity in the humidifier. Humidifiers typically include flow plates with a flow channel structure, and these channels are in contact with a water-permeable medium, typically configured as a semipermeable membrane such as a water-permeable membrane. Typically, an assembly consists of multiple flow plates with a water-permeable membrane disposed between them.

[0004] For example, on one side of a semipermeable membrane, a wet gas, such as a fuel cell exhaust gas, is directed through the channels of an adjacent flow plate, while on the other side of the semipermeable membrane, a dry gas, such as fresh air, flows through the channels of another flow plate, where the wet gas releases moisture to the semipermeable membrane on one side and the semipermeable membrane releases moisture to the dry gas on the other side. Summary of the Invention

[0005] The object of the present embodiment is to provide an improved membrane element, particularly for a humidifier in a fuel cell system.

[0006] Another object is to provide an improved humidifier for a fuel cell system comprising such a membrane element.

[0007] According to one aspect of the embodiment, this object is achieved by a membrane element for a humidifier, particularly for a fuel cell system, comprising a membrane media bellows including a zigzag-pleated, moisture-permeable but gas-impermeable membrane media, the membrane media bellows extending at least partially circumferentially about a longitudinal axis, the membrane media bellows further including pleats extending substantially parallel to the longitudinal axis, the membrane media bellows further having inner pleat folds at an inner periphery and outer pleat folds at an outer periphery. The membrane element further comprises a support having a hollow body and an outer wall disposed about the inner periphery of the membrane media bellows, the support further having a support inlet at one end and a support outlet at an opposite end, the outer wall of the support having circumferentially disposed fluid-permeable passages therethrough at each end of the support. The membrane element further comprises a bypass valve integrated into the support for selectively blocking and opening the fluid passages through the support.

[0008] According to another aspect of the embodiment, a further object is achieved by a humidifier for a fuel cell system, the humidifier comprising a housing having an inlet for a first fluid, particularly supply air of the fuel cell system, an inlet for a second fluid, particularly exhaust gas of the fuel cell system, and an outlet for the first fluid and an outlet for the second fluid. The humidifier further comprises a membrane element as described above, the membrane element being disposed within the housing, at least a portion of the outer periphery of the membrane medium bellows being fluidly connected to the inlet for the second fluid and the outlet for the second fluid, the support inlet being fluidly connected to the inlet for the first fluid, and the support outlet being fluidly connected to the outlet for the first fluid. The humidifier further comprises an actuator connected to a bypass valve for actuating the bypass valve in response to at least one operating parameter of the humidifier.

[0009] Advantageous embodiments emerge from the dependent claims, the description and the drawings.

[0010] The proposed membrane element for a humidifier, particularly for a fuel cell system, can optimize the efficiency of the fuel system. The membrane element employs a circular design in which the membrane is folded and pleated. In use in a humidifier, a moisture-containing medium diffuses from one side of the membrane to the other. The moisture passes through the membrane, but gas does not.

[0011] The pleats of the membrane media bellows may be bent into a crescent shape to minimize leak paths along the folds or tips of the pleats, allowing for a space-saving, compact design of the humidifier.

[0012] The grid layers of membrane media separated by membranes ensure a certain distance between the different membranes, separating the wet and dry gas streams and allowing efficient moisture transport through the membranes. As an alternative to the grid layers (which may be of different qualities), the membranes may be provided with spacer beads or may be pleated.

[0013] Despite the additional function of the grid layer, a support grid can also be employed to create turbulence and ensure optimal water exchange.Instead of providing a support grid as a grid layer, pre-fabricated plates can be placed between the pleats of the membrane media.

[0014] The support presents a hollow body, into which a bypass valve is integrated, which, in the event of excess humidity, reduces or limits the pressure loss and directs the first fluid, e.g., dry supply air, past the humidifier stack through the interior of the supply body. Advantageously, this allows a significant reduction in pressure loss, particularly since the humidifiers only need to be switched on at certain operating points.

[0015] The bypass valve may operate in a standard spring-loaded manner, but may also be externally controlled to activate the humidifier only under certain operating conditions. The valve element of the bypass valve may be connected to an external actuator that may be configured to activate the bypass valve in response to at least one operating parameter of the humidifier. The actuator may be located, for example, within the humidifier housing.

[0016] The valve body may be designed with a conical diffuser to optimize the flow of the first fluid for distribution within the humidifier. An outlet opening may be provided on the outlet side.

[0017] According to an advantageous embodiment of the membrane element, a bypass valve may be disposed between the fluid-permeable passages of the support, such that in an open state of the bypass valve, the first fluid, e.g., dry feed air, bypasses the membrane region rather than entering through the passages, minimizing moisture transfer from the wet exhaust gas to the dry feed air.

[0018] According to an advantageous embodiment of the membrane element, the bypass valve may comprise a valve body and a valve seat arranged inside an outer wall surrounding the internal opening of the support, such that in the closed state of the bypass valve the fluid passage through the interior of the support can be effectively blocked.

[0019] According to an advantageous embodiment of the membrane element, the bypass valve may further comprise a spring element for preloading the valve disc. The support may further comprise an abutment arranged on the support and supporting the spring element. Advantageously, in the inactive state of the bypass valve, the valve disc rests on the valve seat, thereby closing the fluid passage. The humidifier operates in a normal state transferring moisture from the humid exhaust gas to the dry supply air.

[0020] According to an advantageous embodiment of the membrane element, the valve disc may be rotatable about an axis intersecting the longitudinal axis, In an alternative embodiment, the valve disc may be driven, for example, by an external actuator, to rotate from a closed position to an open position.

[0021] According to an advantageous embodiment of the membrane element, the valve body may include a diffuser directed toward the intended upstream side of the support along the longitudinal axis, which may be conical in shape to optimize the flow of the first fluid for its distribution function within the humidifier, thereby advantageously directing the moist gas into the fluid-permeable passages in the outer wall of the support.

[0022] According to a preferred embodiment of the membrane element, the membrane element further comprises a fluid-tight sleeve and / or a fluid-tight sealant at least partially covering the outer periphery of the membrane media bellows along its axial extension. Advantageously, a forced gas flow through the pleats on the outer periphery of the membrane media bellows ensures good moisture transfer to the drying gas. For example, a wound thread, a plastic tape, or a hot melt is advantageously used as the fluid-tight sealant.

[0023] According to an advantageous embodiment of the membrane element, the membrane element may further comprise end bodies, in particular end caps, which close the membrane media bellows at their axial ends in a fluid-tight manner. In this way, the axial ends of the membrane media bellows can be advantageously sealed. Nevertheless, the membrane media bellows are mechanically stabilized during handling during storage, installation, and removal processes.

[0024] The proposed humidifier, especially for fuel cell systems, can optimize the efficiency of the fuel system. The membrane element has a circular design with folded and pleated membranes, allowing for good diffusion of the moisture-containing medium from one side of the membrane to the other. Moisture passes through the membrane, but gas does not.

[0025] The pleats of the membrane media bellows may be bent into a crescent shape to minimize leak paths along the folds or tips of the pleats, allowing for a space-saving, compact design of the humidifier.

[0026] The grid layers of membrane media separated by membranes ensure a certain distance between the different membranes, separating the wet and dry gas streams and allowing efficient moisture transport through the membranes. As an alternative to the grid layers (which may be of different qualities), the membranes may be provided with spacer beads or may be pleated.

[0027] However, to achieve optimal water exchange, a support grid can be employed to create turbulence.Instead of providing a support grid as a grid layer, pre-fabricated plates can be placed between the pleats of the membrane medium.

[0028] The support for the membrane elements presents a hollow body, to which a bypass valve is integrated, which, in the event of excess humidity, reduces the pressure loss and directs the first fluid, e.g., dry supply air, past the humidifier stack through the interior of the supply body. Advantageously, this allows a significant reduction in pressure loss, especially since the humidifiers only need to be switched on at specific operating points.

[0029] The bypass valve may operate in a standard spring-loaded manner, but may also be externally controlled to activate the humidifier only under certain operating conditions. The valve element of the bypass valve may be connected to an external actuator that may be configured to activate the bypass valve in response to at least one operating parameter of the humidifier.

[0030] The actuator of the bypass valve may be located, for example, within the housing of the humidifier. Different types of actuators are possible. The actuator may be a thermostat, for example including an electrically heated spring element, which may activate the humidifier at a higher temperature. Bimetallic actuators and shape memory alloy-driven actuators, for example in the form of a spiral spring element, are also conceivable. The actuation of the bypass valve may be achieved, for example, by a gear rack combined with a dovetail guide or the like.

[0031] The valve body may be designed with a conical diffuser to optimize the flow of the first fluid for distribution within the humidifier. An outlet opening may be provided on the outlet side.

[0032] According to an advantageous embodiment of the humidifier, the humidifier may further comprise a water separator connected to the inlet for the second fluid and comprising a cyclone, a radial water separation chamber and a water outlet, so that any standard water separator can be connected to the second fluid, the wet exhaust gas, in order to remove excess water in the gas, which is preferred when the exhaust gas contains excess moisture.

[0033] According to an advantageous embodiment of the humidifier, the humidifier may further comprise a circumferential sealing element at the outer periphery of the membrane medium bellows for sealing at least a portion of the outer periphery against the housing wall of the housing, thereby providing a gas flow that provides advantageous moisture transfer to the drying gas.

[0034] According to an advantageous embodiment of the humidifier, the humidifier may further include a potting material disposed at the front of the interior of the housing for sealing one axial end of the membrane media bellows. The membrane media bellows may be connected to the housing at one axial end by the potting material, and the other axial end of the membrane media bellows may be sealed by a housing cover of the housing. This allows the membrane media bellows to be directly attached to the humidifier housing and sealed to the housing. Therefore, there is no need to provide an additional sealing element to control gas flow for favorable moisture transfer to the dry gas.

[0035] According to an advantageous embodiment of the humidifier, either or any combination of the inlet for the second fluid and the outlet for the second fluid may comprise a diffuser, which advantageously directs the dry gas to flow between the pleats on the periphery of the membrane media bellows.

[0036] The present embodiments, together with these and other objects and advantages, can be best understood from the following detailed description of exemplary embodiments, but are not limited to these embodiments. [Brief explanation of the drawings]

[0037] [Figure 1] 1 is a cross-sectional view of a humidifier for a fuel cell system according to an embodiment with a bypass valve in a closed state. [Figure 2] 2 is a humidifier according to FIG. 1 with the bypass valve in an open position. [Figure 3] FIG. 10 is a cross-sectional view of a humidifier for a fuel cell system according to another embodiment with a bypass valve in a closed state. [Figure 4] 4 is a humidifier according to FIG. 3 with the bypass valve in an open position. DETAILED DESCRIPTION OF THE INVENTION

[0038] In the drawings, like elements are marked with the same reference numerals. The drawings are merely schematic representations and are not intended to depict specific parameters of the embodiments. Also, the drawings are intended to depict only typical embodiments and should not be considered as limiting the scope of the embodiments.

[0039] FIG. 1 shows a cross-sectional view of a humidifier 100 for a fuel cell system according to an embodiment with a bypass valve 30 in a closed state 1.

[0040] The humidifier 100 has a housing 110 having at least one inlet 102 for a first fluid 80, in particular the supply air of a fuel cell system, an inlet 106 for a second fluid 82, in particular the exhaust gas of a fuel cell system, an outlet 104 for the first fluid 80, and an outlet 108 for the second fluid 82. The housing 110 comprises a pot-shaped housing body 112, which is closed by a housing cover 114 and sealed by a circumferential sealing element 72. The housing cover 114 is connected to the housing body 112 by a plurality of locking bolts 126.

[0041] Membrane element 10 is disposed within housing 110. Membrane element 10 includes a zigzag pleated membrane media bellows 12 having a membrane media. Membrane media bellows 12 extends at least partially circumferentially about a longitudinal axis 14. Pleats 16 of membrane media bellows 12 extend substantially parallel to longitudinal axis 14. Membrane media bellows 12 has inner pleat folds 20 at an inner periphery 18 and outer pleat folds 24 at an outer periphery 22.

[0042] Disposed about the inner periphery 18 of the membrane media bellows 12 is a support 40 having an outer wall 42. The support 40 has a support inlet 46 at one end 50 and a support outlet 48 at an opposite end 52. At each end 50, 52 of the support 40, a fluid permeable passageway 54, 56 is circumferentially disposed within the outer wall 42 and fluidly connected to the support inlet 46 and the support outlet 48.

[0043] At least a portion of the periphery 22 of the membrane media bellows 12 is fluidly connected to an inlet 106 for the second fluid 82 and an outlet 108 for the second fluid 82. The support inlet 46 is fluidly connected to the inlet 102 for the first fluid 80, and the support outlet 48 is fluidly connected to the outlet 104 for the first fluid 80.

[0044] The membrane element 10 includes a bypass valve 30 for selectively blocking or opening a fluid passageway 38 through the support 40. The fluid passageway 38 is indicated by an arrow, which also indicates the direction of fluid flow when the bypass valve 30 is open and the fluid bypasses the membrane element 10.

[0045] The humidifier 100 includes an actuator 140 connected to the bypass valve 30 for actuating the bypass valve 30 in response to at least one operating parameter of the humidifier 100. The actuator 140 may be located within the housing cover 114, as in the illustrated embodiment. The connection between the actuator 140 and the bypass valve 30 is not shown in the figures.

[0046] The bypass valve 30 is disposed between the fluid permeable passages 54, 56 of the support 40. The valve seat 32 of the valve body 31 is disposed inside the outer wall 42 that surrounds the internal opening 36 of the support 40.

[0047] 1 and 2, a spring element 33 is provided to preload the valve body 31. The spring element 33 is supported on the support 40, in particular on an abutment 35 arranged on the support 40. In the closed state 1 of the bypass valve 30 shown in FIG. 1, the valve body 31 is pressed against the valve seat 32 by the spring element 33, thereby blocking the fluid passage 38 through the interior 44 of the support 40.

[0048] The valve body 31 includes a diffuser 58 toward the intended upstream side of the support 40 along the longitudinal axis 14, such that the flow of the incoming first fluid, particularly dry supply air, is directed by the diffuser 58 into the passages 54 in the support 40.

[0049] The inlet 106 for the second fluid 82 includes an optional water separator 130. The water separator 130 is comprised of a cyclone 132 with a diffuser 134 for expanding the second fluid 82, a radial water separation chamber 136 for collecting the separated water, and a water outlet 138 for removing the separated water from the humidifier 100. The water separator 130 is preferred when the exhaust gas contains excess moisture.

[0050] In an alternative embodiment (not shown), the first fluid 80, particularly dry supply air, may be supplied to the second inlet 106 and exit the housing through the second outlet 108, while the second fluid 82, particularly wet exhaust gas, may be supplied to the first inlet 102 and exit through the first outlet 104. In such an embodiment, a water separator 130 may be connected to the first inlet 102.

[0051] The membrane media bellows 12 includes end bodies 60, 62, particularly end caps, at axial ends 68, 70 that close the membrane media bellows 12 in a fluid-tight manner.

[0052] At least one axial end 70 of membrane media bellows 12 is sealed by potting material 120 disposed on a front surface 118 within housing 110. In particular, membrane media bellows 12 is connected to housing 110 at one axial end 70 via potting material 120, and the other axial end 68 is sealed by housing cover 114 of housing 110.

[0053] The outer periphery 22 of the membrane media bellows 12 is covered, at least partially along the axial extension of the membrane media bellows 12, by a fluid-tight sleeve 34 and / or fluid-tight seal.

[0054] A portion of the outer periphery 22 of the membrane media bellows 12 is sealed against the housing wall 116 of the housing 110 by a circumferential seal element 76 on the outer periphery 22 .

[0055] Thus, second fluid 82, specifically wet exhaust gas, can enter membrane element 10 from outer periphery 22 at a height corresponding to passages 56 in inner periphery 18. Second fluid 82 is directed downwardly over outer periphery 22, thereby transferring moisture through membrane media bellows 12. Second fluid 82 exits membrane media bellows 12 at the lower end, enters annular flow path 128, and exits housing 110 of humidifier 100 through outlet 108.

[0056] The inlet 106 for the second fluid 82 and the outlet 108 for the second fluid 82 may be configured with diffusers 122, 124 for preferred fluid flow. Alternatively, the inlet 106 may be configured with a nozzle.

[0057] In FIG. 2, the humidifier 100 is shown with the bypass valve 30 in the open state 2.

[0058] Spring element 33 presses against abutment 35. Valve disc 31 is lifted from valve seat 32, thereby opening fluid passageway 38 for first fluid 80 to flow through interior 44 of support 40. With bypass valve 30 in open state 2, a majority of first fluid 80, the dry supply air, bypasses membrane media bellows 12 and exits humidifier 100 through outlet 104, rather than entering membrane media bellows 12 through passageway 54 to obtain moisture from second fluid 82, the wet exhaust gas.

[0059] In FIG. 3, a cross-sectional view of a humidifier 100 for a fuel cell system according to another embodiment is shown with the bypass valve 30 in a closed state 1.

[0060] Here, most of the features of the humidifier 100 and the membrane element 10 are the same as in the embodiment shown in Figures 1 and 2. Therefore, the description will not be repeated.

[0061] The main difference is that the valve element 31 is configured to be rotatable about an axis 39 that intersects the longitudinal axis 14. The bypass valve 30 therefore resembles a butterfly valve. The rotational movement of the bypass valve 30 may be actuated, for example, by an actuator 140 arranged in the housing cover 114. Still other possibilities are also possible for actuating the bypass valve 30.

[0062] In FIG. 3, the valve disc 31 is positioned within the valve seat 32 thereby closing the fluid passageway 38 through the interior 44 of the support 40 .

[0063] FIG. 4 shows the humidifier 100 with the bypass valve 30 in the open state 2.

[0064] The valve body 31 is rotated to an upright position, thereby opening the fluid passageway 38 for the first fluid 80 to flow through the interior 44 of the support 40 .

[0065] The second embodiment of the humidifier 100 shown in FIGS. 3 and 4 includes a water separator 130, similar to the first embodiment shown in FIGS. [Explanation of symbols]

[0066] 1 Closed state 2 Open state 10 Membrane elements 12 Membrane medium bellows 14 Longitudinal Axis 16 pleats 18 inner circumference 20 Inner pleat crease 22 Outer circumference 24 outer pleat crease 30 Bypass valve 31 Valve body 32 Valve seat 33 Spring elements 34 Sleeve 35 Contact part 36 Opening 38 Passage 39 axes 40 Support 42 Exterior Wall 44 Internal 46 Support entrance 48 Support outlet 50 End 52 End 54 Passage 56 Passage 58 Diffuser 60 End body 62 End body 68 Axial end 70 Axial end 72 sealing elements 76 sealing elements 80 First Fluid 82 Second Fluid 100 humidifier 102 inlet for first fluid 104 outlet for first fluid 106 inlet for second fluid 108 outlet for second fluid 110 Housing 112 Housing body 114 Housing cover 116 Housing Wall 118 Front 120 Potting material 122 Diffuser 124 Diffuser 126 Locking bolt 128 Annular Channel 130 Water separator 132 Cyclone 134 Diffuser 136 Water separation room 138 Water outlet 140 Actuator

Claims

1. A membrane element (10) for a humidifier (100), comprising: The membrane element (10) a membrane media bellows (12) comprising a zigzag pleated, moisture permeable but gas impermeable membrane media, said membrane media bellows (12) extending at least partially circumferentially about a longitudinal axis (14), said membrane media bellows (12) further including pleats (16) extending substantially parallel to said longitudinal axis (14), said membrane media bellows (12) further having inner pleat folds (20) at an inner periphery (18) and outer pleat folds (24) at an outer periphery (22); a support (40) having a hollow body and an outer wall (42) disposed on the inner periphery (18) of the membrane media bellows (12), the support (40) further having a support inlet (46) at one end (50) and a support outlet (48) at an opposite end (52), the outer wall (42) of the support (40) having circumferentially arranged fluid-permeable passages (54, 56) passing through the outer wall (42) at each end (50, 52) of the support (40); a bypass valve (30) integrated into said support (40), said bypass valve (30) for selectively blocking and opening a fluid passage (38) through said support (40).

2. The membrane element (10) of claim 1, wherein the bypass valve (30) is disposed between the fluid-permeable passages (54, 56) of the support (40).

3. 2. The membrane element (10) according to claim 1, wherein the bypass valve (30) comprises a valve body (31) and a valve seat (32) arranged inside the outer wall (42) surrounding the internal opening (36) of the support (40).

4. The bypass valve (30) further includes a spring element (33) for preloading the valve body (31); 4. The membrane element (10) according to claim 3, wherein the support (40) further comprises an abutment (35) arranged on the support (40) and supporting the spring element (33).

5. 4. The membrane element (10) according to claim 3, wherein the valve body (31) is rotatable about an axis (39) that intersects the longitudinal axis (14).

6. 4. The membrane element (10) of claim 3, wherein the valve body (31) includes a diffuser (58) toward the intended upstream side of the support (40) along the longitudinal axis (14).

7. The membrane element (10) of claim 1 further comprising a fluid-tight sleeve (34) and / or a fluid-tight sealant covering the outer periphery (22) of the membrane medium bellows (12) at least partially along the axial extension of the membrane medium bellows (12).

8. The membrane element (10) of claim 1, further comprising end bodies (60, 62) that fluid-tightly close the membrane media bellows (12) at axial ends (68, 70).

9. A humidifier (100) for a fuel cell system, comprising: The humidifier (100) A housing (110), an inlet (102) for a first fluid (80); an inlet (106) for a second fluid (82); an outlet (104) for said first fluid (80); a housing (110) having an outlet (108) for said second fluid (82); 2. The membrane element (10) of claim 1, wherein the membrane element (10) is disposed within the housing (110), and at least a portion of the outer periphery (22) of the membrane media bellows (12) is fluidly connected to an inlet (106) for the second fluid (82) and an outlet (108) for the second fluid (82), the support inlet (46) is fluidly connected to an inlet (102) for the first fluid (80), and the support outlet (48) is fluidly connected to an outlet (104) for the first fluid (80); an actuator (140) connected to the bypass valve (30) for actuating the bypass valve (30) in response to at least one operating parameter of the humidifier (100).

10. 10. The humidifier of claim 9, further comprising a water separator connected to the inlet for the second fluid, the water separator comprising a cyclone, a radial water separation chamber, and a water outlet.

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