Fuel cell humidifier

Abstract

The present invention provides a humidifier for a fuel cell, which can adjust the humidification amount and differential pressure of the humidifier according to the operating conditions of the fuel cell. [Solution] A humidifier (100) comprising a housing (110) having a humid air supply port (112) formed on one side to which humid air is supplied from a fuel cell stack (200) and a humid air discharge port (114) formed on the other side, and a humidifying membrane (140) provided inside the housing along which dry air flows, and a bypass flow path (111) formed inside the housing that always bypasses a portion of the humid air supplied to the humid air supply port to the humid air discharge port without passing through the humidifying membrane.

Description

[Technical field]

[0001] The present invention relates to a humidifier for a fuel cell, and more particularly to a humidifier for a fuel cell that can adjust the humidification amount and differential pressure of the humidifier according to the operating conditions of the fuel cell. [Background technology]

[0002] 2. Description of the Related Art Fuel cell systems are systems that continuously produce electrical energy through chemical reactions of continuously supplied fuel, and are being continuously researched and developed as an alternative solution to global environmental problems.

[0003] Fuel cell systems can be classified into phosphoric acid fuel cells (PAFCs), molten carbonate fuel cells (MCFCs), solid oxide fuel cells (SOFCs), polymer electrolyte membrane fuel cells (PEMFCs), alkaline fuel cells (AFCs), direct methanol fuel cells (DMFCs), etc. depending on the type of electrolyte used. They can be used in a variety of applications, such as for mobile power sources, transportation, and distributed power generation, depending on the type of fuel used as well as the operating temperature, output range, etc.

[0004] Among these, polymer electrolyte fuel cells are being applied in the field of hydrogen vehicles (hydrogen fuel cell vehicles) which are being developed to replace internal combustion engines.

[0005] A hydrogen vehicle runs by producing electricity through a chemical reaction between hydrogen and oxygen, which then drives a motor. More specifically, a hydrogen vehicle includes a hydrogen tank (H2Tank) in which hydrogen (H2) is stored, a fuel cell that produces electricity through an oxidation-reduction reaction between hydrogen and oxygen (O2), various devices for draining the water produced, a battery that stores the electricity produced by the fuel cell, a controller that converts and controls the electricity produced, and a motor that generates driving force.

[0006] Meanwhile, in order for the fuel cell to operate normally, the electrolyte membrane of the membrane electrode assembly must be maintained at a certain humidity or higher, so the inlet gas may be humidified by a humidifier before being introduced into the fuel cell.

[0007] Recently, a method has been proposed in which moist air exhausted from a fuel cell is used to humidify the incoming gas (dry air) passing through a humidifier.

[0008] In addition, the degree of humidification (humidification amount) of the inflow gas flowing into the fuel cell must be adjustable according to the operating conditions (or humidity state) of the fuel cell.

[0009] However, in the past, a separate bypass flow path was formed outside the humidifier, and the inflow gas was either passed through the humidifier (in a humidified state) and then passed through the fuel cell, or passed directly through a bypass flow path outside the humidifier to the fuel cell without passing through the humidifier, thereby adjusting the humidity of the fuel cell. This resulted in problems such as a complex structure, reduced design freedom and reduced space utilization, and it was difficult to accurately adjust the amount of humidification of the inflow gas according to the operating conditions of the fuel cell.

[0010] In addition, as the humidification performance of the humidifier improves, the amount of humidification of the inflowing gas can be increased; however, in the past, as the amount of humidification of the inflowing gas increases, the differential pressure of the humidifier (the difference in pressure between the inlet and outlet of the humidifier) ​​increases, resulting in a problem of reduced energy efficiency (increased power consumption).

[0011] Furthermore, in the conventional fuel cell, when excessively humidified inlet gas is continuously supplied to the fuel cell, a flooding phenomenon occurs inside the fuel cell.

[0012] Accordingly, various researches have been conducted recently to adjust the amount of humidification of the inlet gas according to the operating conditions of the fuel cell stack while adjusting the pressure difference of the humidifier. However, the researches are still insufficient, and further developments in this field are required. Summary of the Invention [Problem to be solved by the invention]

[0013] An object of the present invention is to provide a humidifier for a fuel cell that can adjust the humidification amount and pressure difference of the humidifier in accordance with the operating conditions of the fuel cell.

[0014] In particular, the present invention aims to minimize the decrease in energy efficiency caused by an increase in the differential pressure of the humidifier.

[0015] Another object of the present invention is to suppress the flooding phenomenon in a fuel cell caused by excessive humidification.

[0016] Another object of the present invention is to simplify the structure and improve the design freedom and space utilization. [Means for solving the problem]

[0017] According to a preferred embodiment of the present invention for achieving the above-mentioned object of the present invention, a humidifier for a fuel cell includes a housing having a moist air supply port on one side through which moist air is supplied from a fuel cell stack and a moist air outlet on the other side, and a humidifying membrane provided inside the housing and along which dry air flows, and a bypass flow path is formed inside the housing for always bypassing a portion of the moist air supplied to the moist air supply port to the moist air outlet without passing through the humidifying membrane.

[0018] This is to adjust the humidification amount and pressure difference of the humidifier in accordance with the operating conditions of the fuel cell.

[0019] In other words, in the past, as the amount of humidification of the inflow gas by the humidifier increased, the differential pressure of the humidifier (the difference in pressure between the inlet and outlet of the humidifier) ​​increased, resulting in a problem of reduced energy efficiency (increased power consumption).

[0020] In addition, when excessively humidified inflow gas is continuously supplied to the fuel cell (eg, when the fuel cell is operating at low power), a flooding phenomenon occurs inside the fuel cell.

[0021] However, the present invention provides the advantageous effect of preventing an excessive increase in the differential pressure of the humidifier by always bypassing a portion of the moist air supplied to the inside of the housing through the moist air supply port to the moist air outlet without passing through the humidifying membrane, thereby minimizing the decrease in energy efficiency caused by an increase in the differential pressure of the humidifier.

[0022] In addition, since a portion of the moist air supplied to the inside of the housing is bypassed to the moist air outlet without passing through the humidifying membrane, the amount of humidification of the dry air can be reduced, which has the advantageous effect of preventing flooding caused by excessive humidification when the fuel cell stack is operating at low power.

[0023] More specifically, the housing includes a housing body in which the humidifying membrane is accommodated and in which a first flow path wall is formed and disposed on the upper part of the humidifying membrane, and a housing cap in which a second flow path wall is formed and disposed at a distance from the upper part of the first flow path wall and which is coupled to the upper part of the housing body, the first flow path wall and the second flow path wall cooperating with each other to form a bypass flow path.

[0024] Preferably, the bypass flow passage is adapted to have a cross-sectional area that can be selectively varied. By selectively varying the cross-sectional area of ​​the bypass flow passage in this manner, the bypass flow rate of the moist air that is bypassed through the bypass flow passage among the moist air supplied to the housing can be selectively adjusted, so that the humidification amount of the moist air and the pressure difference of the humidifier can be adjusted according to the operating conditions (or humidity state) of the fuel cell stack.

[0025] The cross-sectional area of ​​the bypass passage may be varied in various ways depending on required conditions and design specifications.

[0026] For example, the housing cap includes a first cap member having a second flow path wall disposed at a first height (H1) relative to the first flow path wall and coupled to the housing body, and a second cap member having a second flow path wall disposed at a second height (H2) different from the first height (H1) and coupled to the housing body, and the cross-sectional area of ​​the bypass flow path can be changed by coupling either one of the first cap member or the second cap member to the housing body.

[0027] As another example, a humidifier for a fuel cell includes a first partition member formed to have a first size (L1) and partially blocking the bypass flow path, and a second partition member formed to have a second size (L2) different from the first size (L1) and partially blocking the bypass flow path, and one of the first partition member and the second partition member can be disposed inside the bypass flow path to vary the cross-sectional area of ​​the bypass flow path.

[0028] As another example, a humidifier for a fuel cell includes a shutoff member that partially opens and closes the bypass flow path, and a control unit that controls the opening and closing of the shutoff member in response to the humidity of the fuel cell stack, and can open and close the shutoff member to vary the cross-sectional area of ​​the bypass flow path.

[0029] For example, the blocking member may include a lifting unit coupled to the second flow path wall so as to be liftable and lowerable, and configured to selectively lift and lower the blocking member, and the control unit controls the lifting unit in response to the humidity of the fuel cell stack.

[0030] Preferably, the control unit may lower the blocking member to reduce the cross-sectional area of ​​the bypass flow path if the humidity of the fuel cell stack is lower than the target humidity range, and may raise the blocking member to expand the cross-sectional area of ​​the bypass flow path if the humidity of the fuel cell stack is higher than the target humidity range. [Brief description of the drawings]

[0031] [Figure 1] 1 is a diagram for explaining a fuel cell system to which a humidifier for a fuel cell according to the present invention is applied; [Diagram 2] FIG. 1 is a diagram for explaining a humidifier for a fuel cell according to a first embodiment of the present invention. [Diagram 3] FIG. 1 is a diagram for explaining a humidifier for a fuel cell according to a first embodiment of the present invention. [Figure 4] FIG. 4 is a diagram for explaining a humidifier for a fuel cell according to a second embodiment of the present invention. [Diagram 5] FIG. 4 is a diagram for explaining a humidifier for a fuel cell according to a second embodiment of the present invention. [Figure 6] FIG. 11 is a diagram for explaining a humidifier for a fuel cell according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited or restricted by the embodiments. In this description, the same numbers refer to substantially the same elements, and based on such rules, the contents described in other drawings may be quoted and described, and the contents that are considered to be obvious to a person skilled in the art or that are repeated may be omitted.

[0033] FIG. 1 shows a method for manufacturing a semiconductor device according to the present invention. Fig. 2 is a diagram for explaining a fuel cell system to which a humidifier for a fuel cell according to the present invention is applied. Figs. 2 and 3 are diagrams for explaining a humidifier for a fuel cell according to a first embodiment of the present invention. Figs. 4 and 5 are diagrams for explaining a humidifier for a fuel cell according to a second embodiment of the present invention. Fig. 6 is a diagram for explaining a humidifier for a fuel cell according to a third embodiment of the present invention.

[0034] As shown in Figures 1 to 6, the humidifier 100 for a fuel cell according to the present invention includes a housing 110 having a moist air supply port 112 formed on one side through which moist air is supplied from a fuel cell stack 200 and a moist air discharge port 114 formed on the other side, and a humidifying membrane 140 provided inside the housing 110 along which dry air flows. A bypass flow path 111 is formed inside the housing 110 to constantly bypass a portion of the moist air supplied to the moist air supply port 112 to the moist air discharge port 114 without passing through the humidifying membrane 140.

[0035] The humidifier 100 for a fuel cell according to the present invention is provided to humidify an inlet gas (eg, air) flowing into a fuel cell stack 200 .

[0036] Incidentally, the fuel cell stack 200 may be formed in various structures capable of producing electricity through an oxidation-reduction reaction between a fuel (eg, hydrogen) and an oxidant (eg, air).

[0037] For example, the fuel cell stack 200 includes a membrane electrode assembly (MEA) (not shown) having a catalyst electrode layer attached to both sides of a membrane where an electrochemical reaction occurs, the electrolyte membrane through which hydrogen ions move, a gas diffusion layer (GDL) (not shown) that plays a role in uniformly distributing the reactant gas and transmitting the generated electrical energy, gaskets and fasteners (not shown) for maintaining airtightness of the reactant gas and coolant and an appropriate fastening pressure, and a bipolar plate (not shown) for moving the reactant gas and coolant.

[0038] More specifically, in the fuel cell stack 200, hydrogen as a fuel and air (oxygen) as an oxidant are supplied to the anode and cathode of the membrane electrode assembly, respectively, through the flow paths of the separator plate, with hydrogen being supplied to the anode and air being supplied to the cathode.

[0039] Hydrogen supplied to the anode is decomposed into hydrogen ions (protons) and electrons by the catalyst in the electrode layers on both sides of the electrolyte membrane, and only the hydrogen ions are selectively transferred to the cathode through the electrolyte membrane, which is a cation exchange membrane, while the electrons are transferred to the cathode through the conductors, the gas diffusion layer and the separator.

[0040] In the cathode, hydrogen ions supplied through the electrolyte membrane and electrons transferred through the separator react with oxygen in the air supplied to the cathode by an air supply device to produce water. The movement of hydrogen ions causes a flow of electrons through an external conductor, which generates an electric current.

[0041] The housing 110 is provided to have a predetermined storage space therein. The shape and structure of the housing 110 may be variously changed according to required conditions and design specifications, and the present invention is not limited or restricted by the shape and structure of the housing 110. For example, the housing 110 may be formed in a rectangular box shape having a storage space therein.

[0042] A dry air supply port (not shown) through which dry air is supplied is formed on one side of the housing 110, and a dry air discharge port (not shown) through which dry air is discharged is formed on the other side of the housing 110.

[0043] For example, with reference to FIG. 1, a dry air supply port (not shown) through which dry air is supplied is formed at a right end of the housing 110, and a dry air exhaust port (not shown) is formed at a left end of the housing 110.

[0044] Incidentally, the dry air supplied to the dry air supply port may be humidified while passing through the humidifying membrane 140, and the humidified air (humidified dry air) discharged through the dry air exhaust port may be supplied to the fuel cell stack 200.

[0045] In addition, a moist air supply port 112 is formed on one side of the housing 110 (for example, the upper left end in reference to FIG. 1), and a moist air exhaust port 114 is formed on the other side of the housing 110 (for example, the upper right end in reference to FIG. 1).

[0046] The moist air (or generated water) discharged from the fuel cell stack 200 may flow into the interior of the housing 110 along a connecting flow path (not shown) connecting the fuel cell stack 200 and the moist air supply port 112 of the housing 110, and inside the housing 110, the moist air may be used to humidify the dry air flowing along the humidifying membrane 140.

[0047] The humidifying membrane 140 is provided inside the housing 110 and allows dry air to flow along its interior.

[0048] For example, the humidifying membrane 140 is formed as a tubular hollow fiber membrane along which dry air can flow, and one end (inlet end) and the other end (outlet end) of the humidifying membrane 140 are fixed inside the housing 110 by a potting material 142.

[0049] Incidentally, since the humidifying membrane 140 is formed as a hollow fiber membrane, moisture (e.g., moisture in moist air) supplied to the inside of the housing 110 can permeate from the outside of the humidifying membrane 140 to the inside of the humidifying membrane 140 and be transmitted to dry air, but dry air cannot permeate from the inside of the humidifying membrane 140 to the outside of the humidifying membrane 140.

[0050] In addition, inside the housing 110, a bypass flow path 111 is formed which always causes a portion of the moist air supplied to the moist air supply port 112 to bypass the moist air discharge port 114 without passing through the humidifying membrane 140.

[0051] In this way, by constantly bypassing a portion of the moist air supplied to the inside of the housing 110 to the moist air outlet 114, it is possible to advantageously prevent the differential pressure of the humidifier 100 from increasing excessively, thereby reducing the amount of power consumption caused by the increase in the differential pressure.

[0052] In addition, since a portion of the moist air supplied to the inside of the housing 110 is bypassed to the moist air outlet 114 without passing through the humidifying membrane 140, the amount of humidification of the dry air can be reduced, which has the advantageous effect of preventing flooding caused by excessive humidification when the fuel cell stack 200 is operating at low power.

[0053] More specifically, the housing 110 includes a housing body 120 in which the humidifying membrane 140 is accommodated and on which a first flow path wall 122 is formed and disposed on the upper part of the humidifying membrane 140, and a housing cap 130 on which a second flow path wall 132 is formed and disposed at a distance from the upper part of the first flow path wall 122 and which is connected to the upper part of the housing body 120, and the first flow path wall 122 and the second flow path wall 132 cooperate with each other to form a bypass flow path 111.

[0054] Here, the first flow path wall 122 and the second flow path wall 132 cooperate with each other to form the bypass flow path 111, which is defined as a portion of the wall surface of the bypass flow path 111 being formed by the first flow path wall 122, and another wall surface of the bypass flow path 111 being formed by the second flow path wall 132.

[0055] For example, the bottom surface of the bypass flow passage 111 may be formed by the first flow passage wall 122, and the ceiling surface of the bypass flow passage 111 may be formed by the second flow passage wall 132. According to another embodiment of the present invention, a first extension wall (not shown) bent upwardly is formed at a side end of the first flow passage wall, and a second extension wall (not shown) bent downwardly is formed at a side end of the second flow passage wall, so that both side surfaces of the bypass flow passage are formed by the first extension wall and the second extension wall.

[0056] Incidentally, a portion of the moist air that flows into the housing 110 through the moist air supply port 112 flows along the bypass flow path 111 and is then immediately discharged to the outside of the housing 110 through the moist air exhaust port 114, while the remainder of the moist air that flows into the housing 110 through the moist air supply port 112 flows along the humidification flow path (the lower space of the bypass flow path based on Figure 1) (not shown) that passes through the humidifying membrane 140 and is then discharged to the outside of the housing 110 through the moist air exhaust port 114.

[0057] Preferably, the bypass flow passage 111 has a cross-sectional area that can be selectively varied.

[0058] In this manner, by selectively varying the cross-sectional area of ​​the bypass flow passage 111, the bypass flow rate of the moist air bypassed through the bypass flow passage 111 from the moist air supplied to the housing 110 can be selectively adjusted, so that it is possible to adjust the humidification amount of the humidified air and the pressure difference of the humidifier 100 according to the operating conditions (or humidity state) of the fuel cell stack 200.

[0059] This is because the humidification amount of the humidified air and the pressure difference of the humidifier 100 can be adjusted by controlling the bypass flow rate of the moist air bypassed via the bypass flow path 111.

[0060] For example, as the cross-sectional area of ​​the bypass flow passage 111 is reduced (reduced), the bypass flow rate of the moist air bypassed through the bypass flow passage 111 decreases, while the flow rate of the moist air flowing along the humidification flow passage increases.

[0061] If the flow rate of the moist air flowing along the humidification flow path increases, the amount of humidification of the humidified air increases and the performance of the fuel cell stack 200 improves; however, the differential pressure of the humidifier 100 (the pressure difference between the inlet and outlet of the housing 110) increases, resulting in higher power consumption.

[0062] Conversely, as the cross-sectional area of ​​the bypass flow passage 111 is increased (expanded), the bypass flow rate of the moist air bypassed through the bypass flow passage 111 increases, and the flow rate of the moist air flowing along the humidification flow passage decreases.

[0063] If the flow rate of moist air flowing along the humidification flow path is reduced, the pressure difference in the humidifier 100 is lowered and power consumption is reduced, but the amount of humidification of the humidified air is reduced and the performance of the fuel cell stack 200 is reduced.

[0064] Therefore, by selectively varying the cross-sectional area of ​​the bypass flow path 111, it is possible to adjust the humidification amount of the humidified air and the pressure difference of the humidifier 100 according to the operating conditions (or humidity state) of the fuel cell stack 200.

[0065] The cross-sectional area of ​​the bypass passage 111 may be varied in various ways depending on required conditions and design specifications.

[0066] For example, the housing cap 130 may include a plurality of cap members in which the second flow path walls 132 are formed at different heights, and the cross-sectional area of ​​the bypass flow path 111 can be varied by alternating the cap members.

[0067] More specifically, as shown in Figures 2 and 3, the housing cap 130 includes a first cap member 130' having a second flow passage wall 132 disposed at a first height (H1) relative to the first flow passage wall 122 and coupled to the housing body 120, and a second cap member 130'' having a second flow passage wall 132 disposed at a second height (H2) different from the first height (H1) and coupled to the housing body 120, and the cross-sectional area of ​​the bypass flow passage 111 can be changed by coupling either one of the first cap member 130' and the second cap member 130'' to the housing body 120.

[0068] More specifically, as shown in FIG. 2, the first cap member 130′ is formed with the second flow path wall 132 disposed at a first height (H1) relative to the first flow path wall 122, and the cross-sectional area (CS1) of the bypass flow path 111 may be determined by the second flow path wall 132 and the first flow path wall 122 disposed at the first height (H1).

[0069] As shown in FIG. 3, the second cap member 130'' is formed with a second flow path wall 132 disposed at a second height (H2) higher than the first height (H1), and the cross-sectional area (CS2) of the bypass flow path 111 may be determined by the second flow path wall 132 disposed at the second height (H2) and the first flow path wall 122.

[0070] 2 and 3, when the second cap member 130'' is coupled to the housing body 120, the bypass is smaller than when the first cap member 130' is coupled to the housing body 120. The cross-sectional area of ​​the flow passage 111 is expanded (CS2>CS1). Conversely, when the first cap member 130' is coupled to the housing body 120, the cross-sectional area of ​​the bypass flow passage 111 is reduced (CS1>CS2) compared to when the second cap member 130'' is coupled to the housing body 120. <CS2)される。

[0071] In the embodiment of the present invention described above and shown in the figures, an example is given in which the cross-sectional area of ​​the bypass flow path 111 is varied by using two cap members in which the second flow path walls 132 are formed at different heights. However, according to other embodiments of the present invention, it is also possible to vary the cross-sectional area of ​​the bypass flow path by using three or more cap members in which the second flow path walls are formed at different heights.

[0072] As another example, the fuel cell humidifier 100 may include multiple partition members of different sizes that partially block the bypass flow path 111, and the cross-sectional area of ​​the bypass flow path 111 can be varied by alternating the partition members.

[0073] More specifically, as shown in Figures 4 and 5, the humidifier 100 for a fuel cell includes a first partition member 150 formed to have a first size (L1) and partially blocking the bypass flow path 111, and a second partition member 150' formed to have a second size (L2) different from the first size (L1) and partially blocking the bypass flow path 111, and one of the first partition member 150 and the second partition member 150' can be disposed inside the bypass flow path 111 to change the cross-sectional area of ​​the bypass flow path 111.

[0074] In the present invention, the first partition member 150 and the second partition member 150' having different sizes is defined as being different from each other in at least one of the length, width, height, and area of ​​the first partition member 150 and the second partition member 150'.

[0075] 4, the first partition member 150 is formed to have a first size (L1) and is disposed inside the bypass flow passage 111 to partially block the bypass flow passage 111, and the cross-sectional area (CS1) of the bypass flow passage 111 may be determined by the first partition member 150 having the first size (L1) and the first flow passage wall 122 (or the second flow passage wall). For example, a coupling groove 134 may be formed on the inner surface of the second flow passage wall 132, and the first partition member 150 may be coupled to the coupling groove 134 to partially block the bypass flow passage 111.

[0076] 5, the second partition member 150' is formed to have a second size (L2) larger than the first size (L1), and the cross-sectional area (CS2) of the bypass flow passage 111 may be determined by the second partition member 150' and the first flow passage wall 122 (or the second flow passage wall). For example, a coupling groove 134 may be formed on the inner surface of the second flow passage wall 132, and the second partition member 150' may be coupled to the coupling groove 134 to partially block the bypass flow passage 111.

[0077] 4 and 5, when the second partition member 150' is coupled to the second flow passage wall 132, the cross-sectional area of ​​the bypass flow passage 111 is enlarged (CS2>CS1) compared to when the first partition member 150 is coupled to the second flow passage wall 132. Conversely, when the first partition member 150 is coupled to the second flow passage wall 132, the cross-sectional area of ​​the bypass flow passage 111 is reduced (CS1) compared to when the second partition member 150' is coupled to the second flow passage wall 132. <CS2)される。

[0078] In the embodiment of the present invention described above and shown in the figures, an example has been given in which the cross-sectional area of ​​the bypass flow path 111 is varied by using two partition members having different sizes. However, according to other embodiments of the present invention, it is also possible to vary the cross-sectional area of ​​the bypass flow path by using three or more partition members having different sizes.

[0079] As another example, the fuel cell humidifier 100 may include a blocking member 160 that partially opens and closes the bypass flow passage 111, and by opening and closing the blocking member 160, the cross-sectional area of ​​the bypass flow passage 111 can be varied.

[0080] More specifically, as shown in FIG. 6, the fuel cell humidifier 100 includes a shutoff member 160 that partially opens and closes the bypass flow path 111, and a control unit 180 that controls the opening and closing of the shutoff member 160 in response to the humidity of the fuel cell stack 200, and can vary the cross-sectional area (ΔCS) of the bypass flow path 111 by opening and closing the shutoff member 160.

[0081] For example, the blocking member 160 may be connected to the second flow path wall 132 so as to be able to rise and fall, and may include a lifting unit 170 that selectively lifts and lowers the blocking member 160, and the control unit 180 controls the lifting unit 170 in response to the humidity of the fuel cell stack 200.

[0082] The blocking member 160 is coupled to the second flow path wall 132 so as to be movable up and down, and the bypass flow path 111 may be partially blocked depending on the extent to which the blocking member 160 protrudes (opens and closes) on the inner surface of the second flow path wall 132 as it moves up and down.

[0083] The lifting unit 170 may be formed in various structures capable of lifting and lowering the blocking member 160, and the present invention is not limited or restricted by the structure and lifting method of the lifting unit 170. For example, the lifting unit 170 may be configured to lift and lower the blocking member 160 by a lead screw rotated by a motor. According to another embodiment of the present invention, the lifting unit may be configured to lift and lower the blocking member using a linear motor, a solenoid, or the like.

[0084] The control unit 180 is provided to control the lifting unit 170 in response to the humidity of the fuel cell stack 200, and the control unit 180 can control whether the blocking member 160 is lifted or lowered and the height to which it is lifted or lowered.

[0085] For example, if the humidity of the fuel cell stack 200 is lower than the target humidity range (low humidification state), the control unit 180 may lower the blocking member 160 to reduce the cross-sectional area of ​​the bypass flow path 111, and if the humidity of the fuel cell stack 200 is higher than the target humidity range (overly humidification state), the control unit 180 may raise the blocking member 160 to expand the cross-sectional area of ​​the bypass flow path 111. Furthermore, if the humidity of the fuel cell stack 200 is within the target humidity range, the raising and lowering of the blocking member 160 may be stopped.

[0086] In the embodiment of the present invention described above and shown in the drawings, an example has been given in which the cross-sectional area of ​​the bypass flow path 111 is changed as the blocking member 160 is raised and lowered. However, according to other embodiments of the present invention, it is also possible for the blocking member to change the cross-sectional area of ​​the bypass flow path by partially opening and closing the bypass flow path in the manner of a camera aperture or partially opening and closing the bypass flow path in the manner of a sliding door.

[0087] As mentioned above, the present invention has been described with reference to a preferred embodiment. However, it will be understood by those skilled in the art that various modifications and variations of the present invention can be made without departing from the spirit and scope of the present invention as set forth in the claims.

[0088] As described above, the present invention provides the advantageous effect of adjusting the humidification amount and pressure difference of the humidifier according to the operating conditions of the fuel cell.

[0089] In particular, the present invention advantageously minimizes the loss of energy efficiency due to an increase in the differential pressure of the humidifier.

[0090] Furthermore, the present invention has the advantageous effect of suppressing the flooding phenomenon in the fuel cell caused by excessive humidification.

[0091] Furthermore, the present invention provides the advantageous effects of simplifying the structure, improving design freedom, and improving space utilization. [Explanation of symbols]

[0092] 100: Humidifier 110: Housing 111: Bypass flow path 112: Wet air supply port 114: Wet air discharge port 120: Housing body 122: First flow path wall 130: Housing cap 130': First cap member 130'': Second cap member 132: Second flow path wall 134: Joint groove 140: Humidifying membrane 150: First partition member 150': Second partition member 160: Blocking member 170: Lifting unit 180: Control unit 200: Fuel cell stack

Claims

1. a housing having a moist air supply port on one side through which moist air is supplied from the fuel cell stack and a moist air discharge port on the other side; a humidifying membrane provided inside the housing, along which dry air flows; and a bypass flow path is formed inside the housing, which causes a portion of the moist air supplied to the moist air supply port to always bypass the moist air discharge port without passing through the humidifying membrane; The housing includes: a housing body in which the humidifying membrane is accommodated and in which a first flow path wall is formed and disposed above the humidifying membrane; a housing cap having a second flow passage wall disposed on an upper portion of the first flow passage wall and spaced apart from the upper portion of the housing body, the housing cap being coupled to an upper portion of the housing body; the first flow path wall and the second flow path wall cooperate with each other to form the bypass flow path, The bypass flow path has a cross-sectional area that is selectively variable, a first partition member formed to have a first size and partially blocking the bypass flow passage; and a second partition member formed to have a second size different from the first size and partially blocking the bypass flow passage, wherein one of the first partition member and the second partition member is disposed inside the bypass flow passage to vary a cross-sectional area of ​​the bypass flow passage, A humidifier for a fuel cell, wherein the cross-sectional area of ​​the bypass passage is variable in response to the humidity of the fuel cell stack while the fuel cell stack is in operation.

2. The humidifier for a fuel cell according to claim 1 , wherein one of the first flow passage wall and the second flow passage wall has a coupling groove to which the first partition member or the second partition member is coupled.

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