Fuel Cell Membrane Humidifier

Abstract

The present invention relates to a fuel cell membrane humidifier that can improve humidification efficiency by adjusting the gap between hollow fiber membranes according to the temperature of a fluid flowing between the hollow fiber membranes, The fuel cell membrane humidifier according to an embodiment of the present invention comprises: The fuel cell stack includes a mid-case, a cap that is fastened to the mid-case, a plurality of hollow fiber membranes that are disposed within the mid-case and exchange moisture between air supplied from the outside and exhaust gas flowing in from the fuel cell stack to humidify the air, and a gap adjustment tube that is disposed between the plurality of hollow fiber membranes and is made of a material having a different thermal expansion coefficient from the plurality of hollow fiber membranes and adjusts the gap between the plurality of hollow fiber membranes according to the temperature of the exhaust gas.

Description

Technical Field

[0001] The present invention relates to a fuel cell membrane humidifier, and more specifically, to a fuel cell membrane humidifier that can adjust the gap between hollow fiber membranes according to the temperature of a fluid flowing between the hollow fiber membranes and improve the humidification efficiency.

Background Art

[0002] A fuel cell is a power generation type battery that combines hydrogen and oxygen to produce electricity. Different from general chemical batteries such as dry batteries and storage batteries, a fuel cell can continue to produce electricity as long as hydrogen and oxygen are supplied, and since there is no heat loss, it has the advantage of being about twice as efficient as an internal combustion engine. In addition, since the chemical energy generated by the combination of hydrogen and oxygen is directly converted into electrical energy, there is less emission of pollutants. Therefore, fuel cells have the advantages of being environmentally friendly and being able to reduce the concern about resource depletion due to increased energy consumption. Such fuel cells can be roughly classified into polymer electrolyte membrane fuel cells (PEMFCs), phosphoric acid fuel cells (PAFCs), molten carbonate fuel cells (MCFCs), solid oxide fuel cells (SOFCs), and alkaline fuel cells (AFCs) according to the type of electrolyte used. Each of these fuel cells originally operates on the same principle, but the types of fuels used, operating temperatures, catalysts, electrolytes, etc. are different from each other. Among these, the polymer electrolyte membrane fuel cell (PEMFC) is known as the most promising not only for small-scale stationary power generation equipment but also for transportation systems because it operates at a lower temperature compared to other fuel cells and has a large output density and can be miniaturized. In improving the performance of a polymer electrolyte fuel cell (PEMFC), one of the most important factors is to maintain the water content by supplying a certain amount or more of water to the polymer electrolyte membrane (Polymer Electrolyte Membrane or Proton Exchange Membrane: PEM) of the membrane-electrode assembly (MEA). This is because if the polymer electrolyte membrane dries out, the power generation efficiency drops sharply. Methods for humidifying the polymer electrolyte membrane include: 1) the bubbler humidification method in which water is filled in an internal pressure vessel and then the target gas is passed through a diffuser to supply moisture; 2) the direct injection method in which the amount of supply moisture required for the fuel cell reaction is calculated and moisture is directly supplied to the gas flow pipe through a solenoid valve; and 3) the humidifying membrane method in which moisture is supplied to the gas flow layer using a polymer separation membrane.

[0003] Among these, the membrane humidification method, which humidifies the polymer electrolyte membrane by supplying water vapor to the air supplied to the polymer electrolyte membrane using a membrane that selectively permeates only the water vapor contained in the exhaust gas, is advantageous in that the membrane humidifier can be made lighter and smaller. The selective permeation membrane used in the membrane humidification method preferably uses a hollow fiber membrane with a large permeation area per unit volume when forming a module. That is, when manufacturing a membrane humidifier using a hollow fiber membrane, high integration of the hollow fiber membrane with a large contact surface area is possible, and even with a small capacity, the fuel cell can be sufficiently humidified, low-cost materials can be used, and the moisture and heat contained in the exhaust gas (off-gas) discharged at a high temperature in the fuel cell can be recovered and reused through the membrane humidifier. Figure 1 is an exploded perspective view showing a fuel cell membrane humidifier according to the prior art. As shown in Figure 1, the prior art fuel cell membrane humidifier 10 includes a humidification module 11 where moisture exchange occurs between the air supplied from the outside and the exhaust gas discharged from a fuel cell stack (not shown), and caps 12 coupled to both ends of the humidification module 11. One of the caps 12 supplies the humidification module 11 with air supplied from the outside, and the other supplies the fuel cell stack with the air humidified by the humidification module 11. The humidification module 11 includes a mid-case 11a having an off-gas inlet 11aa and an off-gas outlet 11ab, and a plurality of hollow fiber membranes 11b within the mid-case 11a. Both ends of the bundle of the hollow fiber membranes 11b are fixed to a potting portion 11c. The potting portion 11c is generally formed by curing a liquid polymer such as a liquid polyurethane resin by a casting method.

[0004] The air supplied from the outside flows along the hollow of the hollow fiber membrane 11b. The exhaust gas flowing into the mid-case 11a through the exhaust gas inlet 11aa contacts the outer surface of the hollow fiber membrane 11b and is then discharged from the mid-case 11a through the exhaust gas outlet 11ab. When the exhaust gas contacts the outer surface of the hollow fiber membrane 11b, the moisture contained in the exhaust gas permeates through the hollow fiber membrane 11b to humidify the air flowing along the hollow of the hollow fiber membrane 11b.

Summary of the Invention

Problems to be Solved by the Invention

[0005] An object of the present invention is to provide a fuel cell membrane humidifier that can adjust the gap between hollow fiber membranes according to the temperature of the fluid flowing between the hollow fiber membranes and improve the humidification efficiency.

Means for Solving the Problems

[0006] The fuel cell membrane humidifier according to an embodiment of the present invention A mid-case, a cap fastened to the mid-case, a plurality of hollow fiber membranes disposed within the mid-case for performing moisture exchange between externally supplied air and exhaust gas flowing in from a fuel cell stack to humidify the air, and a void adjustment tube disposed between the plurality of hollow fiber membranes and formed of a material having a different coefficient of thermal expansion from that of the plurality of hollow fiber membranes for adjusting the voids between the plurality of hollow fiber membranes according to the temperature of the exhaust gas. In the fuel cell membrane humidifier according to an embodiment of the present invention, the void adjustment tube may include a negative thermal expansion material that expands in a first temperature range and contracts in a second temperature range higher than the first temperature range. In the fuel cell membrane humidifier according to an embodiment of the present invention, the void adjustment tube may include bismuth (Bi). In the fuel cell membrane humidifier according to an embodiment of the present invention, the void adjustment tube may include oxides of bismuth (Bi), lanthanum (La), and nickel (Ni). In the fuel cell membrane humidifier according to an embodiment of the present invention, the void adjustment tube may include oxides of bismuth (Bi), iron (Fe), and nickel (Ni). In the fuel cell membrane humidifier according to an embodiment of the present invention, a humidification module may be provided, the humidification module including an inner case for housing the plurality of hollow fiber membranes and at least one cartridge having a potting portion formed at an end of the inner case.

[0007] In a fuel cell membrane humidifier according to an embodiment of the present invention, a body member in which holes into which ends of the cartridge are inserted are formed, and a protruding member that is formed at one end of the body member and contacts the end of the cartridge inserted into the hole to prevent fluid in the mid-case from flowing to the cap side. A packing part, an edge part formed at the other end of the body member, formed in a groove formed at the end of the mid-case and a space formed by the end of the cap, and formed so as to contact the cartridge and the packing part. And a sealing part for preventing fluid in the mid-case from flowing to the cap side. A gasket assembly including the same can be provided. In a fuel cell membrane humidifier according to an embodiment of the present invention, the body member includes two or more holes into which two or more cartridges can be inserted, and two or more of the protruding members are provided. It is formed in contact with each end of the two or more cartridges, and two or more of the sealing parts are provided and can be formed so as to contact each of the two or more cartridges and the packing part. In a fuel cell membrane humidifier according to an embodiment of the present invention, the protruding member can be in contact with the end of the cartridge while pressing it with an elastic force to make the space on the mid-case side and the space on the cap side airtight.

[0008] In a fuel cell membrane humidifier according to an embodiment of the present invention, the edge part includes edge wings protruding in both directions, and the edge wings are interposed while filling a groove formed at the end of the mid-case, and the inside and outside of the mid-case, and the mid-case and the cap can be sealed. In a fuel cell membrane humidifier according to an embodiment of the present invention, each of the packing part and the edge part has a first hardness of 30 to 70 Shore A, and is formed by being inserted into at least a part of the packing part and at least a part of the edge part. A reinforcing member having a second hardness higher than the first hardness can be further provided. In addition, specific details of implementation examples according to various aspects of the present invention are included in the following detailed description.

Advantages of the Invention

[0009] According to the present invention, a void adjustment tube having a different coefficient of thermal expansion from that of the hollow fiber membrane is disposed between the hollow fiber membranes, and the voids between the hollow fiber membranes can be adjusted according to the temperature of the fluid flowing between the hollow fiber membranes, thereby improving the humidification efficiency.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

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Figure 10

Figure 11

Figure 12

Mode for Carrying Out the Invention

[0011] The present invention can be subjected to various conversions and can have various embodiments. Specific embodiments will be exemplified and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and it should be understood that all conversions, equivalents, or alternatives included in the spirit and technical scope of the present invention are included. The terms used in the present invention are merely used to explain specific embodiments and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as "including" or "having" are intended to specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and it should be understood that the presence or addition possibility of one or more other features, numbers, steps, operations, components, parts, or combinations thereof are not precluded in advance. Hereinafter, a fuel cell membrane humidifier according to an embodiment of the present invention will be described with reference to the drawings. FIG. 2 is an exploded perspective view showing a fuel cell membrane humidifier according to a first embodiment of the present invention, and FIG. 3 is a conceptual diagram for explaining an operating state in a humidification module of the fuel cell membrane humidifier according to the first embodiment of the present invention.

[0012] As shown in FIG. 2, a fuel cell membrane humidifier 100 according to an embodiment of the present invention includes a humidification module 110 and a cap 120. The humidification module 110 performs moisture exchange between air supplied from the outside and exhaust gas discharged from a fuel cell stack (not shown). The cap 120 is coupled to both ends of the humidification module 110. One of the caps 120 supplies the air supplied from the outside to the humidification module 110, and the other supplies the air humidified by the humidification module 110 to the fuel cell stack. The humidification module 110 includes a mid-case 111 having an exhaust gas inlet 111a and an exhaust gas outlet 111b, and a plurality of hollow fiber membranes 112 housed in the mid-case 111. An air gap adjustment tube 115 is disposed between the hollow fiber membranes 112. The hollow fiber membranes 112 can include polymer membranes formed of polysulfone resin, polyethersulfone resin, sulfonated polysulfone resin, polyvinylidene fluoride (PVDF) resin, polyacrylonitrile (PAN) resin, polyimide resin, polyamideimide resin, polyesterimide resin, or a mixture of at least two of these. Both ends of the bundle of hollow fiber membranes 112 are fixed to a potting portion 113. The potting portion 113 is generally formed by curing a liquid polymer such as a liquid polyurethane resin by a casting method. Both ends of the air gap adjustment tube 115 can also be fixed to the potting portion 113.

[0013] The air gap adjustment tube 115 is formed of a material having a different coefficient of thermal expansion from that of the hollow fiber membranes 112. The air gap adjustment tube 115 can have a hollow formed therein or can be non-hollow. The coefficient of thermal expansion is preferably a volume expansion coefficient. That is, it is more preferable that the air gap adjustment tube 115 is formed of a material having a different volume expansion coefficient from that of the hollow fiber membranes 112. Specifically, the air gap adjustment tube 115 can include a negative thermal expansion material that expands in a first temperature range and contracts in a second temperature range greater than the first temperature range. That is, the air gap adjustment tube 115 can include a negative thermal expansion material that expands at low temperatures and contracts at high temperatures. Most substances increase in length or volume due to thermal expansion as the temperature rises. In contrast, negative thermal expansion materials have the property of contracting as the temperature rises. Such negative thermal expansion materials can be materials containing bismuth (Bi). Specifically, the negative thermal expansion material can be a material containing oxides of bismuth (Bi), lanthanum (La), and nickel (Ni). More specifically, Bi 0.95 La 0.05 can be NiO3 (bismuth-lanthanum-nickel oxide). Bi 0.95 La 0.05 NiO3 exhibits a negative thermal expansion of 82 parts per million (-82×10 -6 / °C) per 1°C increase in temperature. Also, specifically, the negative thermal expansion material can be a material containing oxides of bismuth (Bi), iron (Fe), and nickel (Ni). More specifically, it can be an oxide BiNi 1-x Fe x O3 (bismuth-nickel-iron oxide) having a structure called "perovskite". BiNi 1-x Fe x O3 exhibits a negative thermal expansion of 187 parts per million (-187×10 -6 / °C) per 1°C increase in temperature in the temperature range near room temperature. Therefore, it can exhibit substantially the same effect even with half the amount compared to Bi 0.95 La 0.05 NiO3.

[0014] The operation of the gap adjustment tube 115 configured as described above will be described with reference to FIG. 3. The air supplied from the outside flows along the inside of the hollow fiber membrane 112. The exhaust gas that has flowed into the mid-case 111 through the exhaust gas inlet 111a comes into contact with the outer surface of the hollow fiber membrane 112 and is then discharged from the mid-case 111 through the exhaust gas outlet 111b. When the exhaust gas comes into contact with the outer surface of the hollow fiber membrane 112, the moisture contained in the exhaust gas permeates through the hollow fiber membrane 112, thereby humidifying the air flowing along the inside of the hollow fiber membrane 112. At this time, the temperature of the exhaust gas changes depending on the output of the fuel cell stack. (a) of FIG. 3 shows the case where the output of the fuel cell stack is high output, and (b) of FIG. 3 shows the case where the output of the fuel cell stack is low output. When the output of the fuel cell stack is less than approximately 40 kW, it can be said to be a low-output environment, and when the output of the fuel cell stack is approximately 40 kW or more, it can be said to be a high-output environment. In a high-output environment, relatively high-temperature exhaust gas is supplied by the fuel cell stack, and in a low-output environment, relatively low-temperature exhaust gas is supplied by the fuel cell stack. Here, the high temperature can be in the range of approximately 50 to 150°C, which can be a second temperature range larger than the first temperature range. Here, the low temperature can be a first temperature range of less than approximately 50°C.

[0015] As shown in FIG. 3(a), since the exhaust gas is at a high temperature, the void adjustment tube 115 having a negative thermal expansion property contracts, and the voids between the hollow fiber membranes 112 expand. As a result, the space through which the high-temperature exhaust gas can flow expands, and the humidification amount and humidification rate of the dry air by the exhaust gas can be adjusted to increase. As shown in FIG. 3(b), since the exhaust gas is at a low temperature, the void adjustment tube 115 having a negative thermal expansion property expands, and the voids between the hollow fiber membranes 112 contract. As a result, the space through which the low-temperature exhaust gas can flow contracts, and the humidification amount and humidification rate of the dry air by the exhaust gas can be adjusted to decrease. According to the first embodiment of the present invention as described above, while being configured with a simple structure without another additional component, the voids between the hollow fiber membranes 112 can be automatically adjusted according to the output status of the fuel cell stack. Therefore, the size of the membrane humidifier can be reduced, and the manufacturing cost can be reduced. Next, a fuel cell membrane humidifier according to a second embodiment of the present invention will be described with reference to FIGS. 4 to 6. FIG. 4 is an exploded perspective view showing the fuel cell membrane humidifier according to the second embodiment of the present invention, FIG. 5 is an exploded cross-sectional view showing the fuel cell membrane humidifier according to the second embodiment of the present invention, and FIG. 6 is an assembled cross-sectional view showing the fuel cell membrane humidifier according to the second embodiment of the present invention. Referring to the conventional membrane humidifier 10 of FIG. 1, a potting portion 11c to which the ends of a plurality of hollow fiber membranes 11b are fixed and a resin layer 11d between the potting portion 11c and the mid-case 11a block the internal space of the cap 12 and the internal space of the mid-case 11a. Similar to the potting portion 11c, the resin layer 11d is generally formed by curing a liquid polymer such as a liquid polyurethane resin by a casting method. However, the casting process for forming the resin layer 11d requires a relatively long process time, thus reducing the productivity of the membrane humidifier 10.

[0016] Also, since the resin layer 11d is adhered not only to the potting portion 11c but also to the inner wall of the mid-case 11a, if a problem occurs in the hollow fiber membrane 11b, the entire humidification module 11 has to be replaced, resulting in huge maintenance and repair costs. Furthermore, the repeated operation of the fuel cell has a high probability of causing a gap between the resin layer 11d and the mid-case 11a. That is, due to the repeated operation and stop of the fuel cell, the resin layer 11d expands and contracts alternately, and due to the difference in the thermal expansion coefficients of the mid-case 11a and the resin layer 11d, there is a high probability that the resin layer 11d will separate from the mid-case 11a. As described above, if a gap is caused between the resin layer 11d and the mid-case 11a, air leakage due to the pressure difference will occur, reducing the amount of humidified air supplied to the fuel cell stack and lowering the power generation efficiency of the fuel cell. To solve such problems, as shown in FIGS. 4 to 6, the fuel cell membrane humidifier 200 of the present invention includes a humidification module 210, a cap 220, and a gasket assembly 230. The humidification module 210 humidifies the air supplied from the outside with the moisture in the exhaust gas discharged from the fuel cell stack. Each of both ends of the humidification module 210 is coupled to a cap 220. Of the caps 220, one supplies the air supplied from the outside to the humidification module 210, and the other supplies the air humidified by the humidification module 210 to the fuel cell stack. The gasket assembly 230 is hermetically coupled to each end of the humidification module 210 through mechanical assembly.

[0017] The humidification module 210 is a device in which moisture exchange occurs between the air supplied from the outside and the exhaust gas, and may include a mid-case 211 having an exhaust gas inlet 211a and an exhaust gas outlet 211b and at least one cartridge 212 disposed within the mid-case 211. The mid-case 211 and the cap 220 can each be independently formed of a rigid plastic or metal and can have a circular or polygonal cross-section in the width direction. The circular shape includes an elliptical shape, and the polygonal shape includes a polygon having rounded corners. For example, the rigid plastic can be polycarbonate, polyamide (PA), polyphthalamide (PPA), polypropylene (PP), etc. The internal space of the mid-case 211 can be partitioned into a first space S1 and a second space S2 by partitions 211c. (See FIG. 8) The cartridge 212 can include a plurality of hollow fiber membranes 212a and a potting portion 212b that fixes them to each other. The ends of the hollow fiber membranes 212a can be fixed to the potting portion 212b. Also, a void adjustment tube 215 is disposed between the hollow fiber membranes 212a. Since the void adjustment tube 215 is substantially the same as the void adjustment tube 115 of the first embodiment described above, repeated description is omitted.

[0018] The gasket assembly 230 can be hermetically coupled to each end of the humidification module 210 through mechanical assembly. Since it prevents air leakage between the mid-case 211 and the cap 220 through the mechanical assembly of the gasket assembly 230, conventional casting processes (i.e., the process of injecting liquid resin into a mold and curing it) and additional sealing processes (i.e., the process of applying and curing a sealant) can be omitted. Also, since the gasket assembly 230 is attached to the humidification module 200 through mechanical assembly, if an abnormality occurs in a specific part of the humidification module 210 (e.g., the cartridge 212), after simply mechanically separating the gasket assembly 230 from the humidification module 210, it is possible to repair or replace only that part. The gasket assembly 230 includes a packing part 231, an edge part 232, and a sealing part 233. The packing part 231 and the edge part 232 can be formed of an elastic material (e.g., silicon, rubber, etc.) having a first hardness of 20 to 70 Shore A, preferably 30 to 60 Shore A. The sealing part 233 can include at least one of a solid-phase sealing material and a liquid-phase sealing material. The solid-phase sealing material can be manufactured from materials such as silicon, acrylic rubber, EPDM, NBR, etc., and the liquid-phase sealing material can be manufactured from materials such as silicon, urethane, etc. The packing part 231 includes a hole H into which an end of the cartridge 212 (e.g., the potting part 212b) is inserted and is interposed between the mid-case 211 and the cartridge 212. The packing part 231 includes a body member 231a and a protruding member 231b.

[0019] The body member 231a is provided with a hole H into which the end portion of the cartridge 212 (for example, the potting portion 212b) is inserted, and the hole H is formed in a shape corresponding to the shape of the end portion of the cartridge 212. The lower body member 231aa protruding from the body member 231a toward the mid-case 211 side can be formed with a polygonal cross-section (for example, a trapezoid), and the upper body member 231ab formed on the cap 220 side can be formed with a planar shape. A space for arranging the sealing portion 233 is formed between the lower body member 231aa and the cartridge potting portion 212b. Further, a groove G for sandwiching the end portion 211d of the mid-case 211 is formed between the lower body member 231aa and the edge portion 232. The protruding member 231b is formed at one end of the body member 231a so as to contact the cartridge potting portion 212b inserted into the hole H. The protruding member 231b can be at least one or more annular protrusions protruding from one end portion of the body member 231a. The protruding member 231b can contact while pressing the cartridge potting portion 212b by an elastic force to make the space in the mid-case 211 and the space by the cap 220 airtight. Therefore, the protruding member 231b can prevent the fluid in the mid-case 211 from flowing into the space formed on the cap 220C side. Further, since the protruding member 231b has elasticity, it can function as a vibration buffer, and thus damage due to the vibration of the humidifier 200 can be prevented.

[0020] The edge portion 232 is formed at the other end of the body member 231a. The edge portion 232 can be interposed in the space formed by the groove 211e formed at the end of the mid-case and the end portion 220a of the cap. The edge portion 232 can include edge wings 232a, 232b protruding in both directions. The edge wings 232a, 232b can be formed in the longitudinal direction of the humidification module 210. During assembly, the edge wings 232a, 232b are inserted into the groove 211e at the end of the mid-case, and after the end portion 220a of the cap presses the edge wing 232b, it can be assembled by tightening with a tightening means such as a bolt B. At this time, since the edge wings 232a, 232b are made of an elastic material, the edge wings 232a, 232b can be interposed while filling a certain portion of the space of the groove 211e at the end of the mid-case. Tightening sections 211cc, 220c with tightening holes for bolt tightening can be formed on the end side surfaces of the mid-case 211 and the cap 220. The edge wings 232a, 232b can airtight the groove 211e at the end of the mid-case and seal the inside and outside of the mid-case 211, and the mid-case 211 and the cap 220.

[0021] The sealing portion 233 is formed so that the cartridge 212 and the packing portion 231 are in contact with each other between the cartridge 212 and the packing portion 231. Specifically, the sealing portion 233 is formed so as to simultaneously contact (or adhere) the potting portion 212b of the cartridge and the lower body member 231aa of the packing portion. The sealing portion 233 airtightens the space of the mid-case 211 and the space of the cap 220 to prevent the fluid in the mid-case 211 from flowing to the cap 220 side. In addition, the gasket assembly 230 can further include a reinforcing member 234. The reinforcing member 234 can have a second hardness higher than the first hardness. For example, the reinforcing member 234 can be formed of metal, a thermoplastic, or a thermosetting resin. The reinforcing member 234 can be formed by being inserted into the gasket assembly 230 after inserting a metal plate into the mold during the molding of the gasket assembly 230. The reinforcing member 234 can be formed by being inserted into at least a part of the packing portion 231 and at least a part of the edge portion 232. The reinforcing member 234 can be formed in a portion of the gasket assembly 230 that is vulnerable to deformation (the portion where the groove G is formed). The reinforcing member 234 having a hardness higher than that of the packing portion 231 and the edge portion 232 can more reliably ensure airtightness by preventing deformation of the body member 231a when the gasket assembly 230 is mechanically assembled to the humidification module 210 or during the operation of the humidifier.

[0022] According to the second embodiment of the present invention as described above, since air leakage between the mid-case 211 and the cap 220 is prevented through the mechanical assembly of the gasket assembly 230, the conventional casting process (i.e., the process of injecting a liquid resin into a mold and curing it) and additional sealing processes (i.e., the process of applying and curing a sealant) can be omitted. Therefore, while preventing air leakage between the mid-case 211 and the cap 220, the production process time of the fuel cell membrane humidifier 200 can be shortened, thereby significantly improving its productivity. In addition, since the gasket assembly 230 is attached to the humidification module 210 through mechanical assembly, if an abnormality occurs in a specific part of the humidification module 210 (for example, the cartridge 212), after easily mechanically separating the gasket assembly 230 from the humidification module 210, only that part can be repaired or replaced. Therefore, according to this embodiment, the maintenance and repair costs of the fuel cell membrane humidifier 200 can be considerably reduced. Next, a modification of the fuel cell membrane humidifier according to the second embodiment of the present invention will be described with reference to FIGS. 7 and 8. FIGS. 7 and 8 are combined cross-sectional views showing a modification of the fuel cell membrane humidifier according to the second embodiment of the present invention.

[0023] As shown in FIGS. 7 and 8, the modifications 200a and 200b of the fuel cell membrane humidifier according to the second embodiment of the present invention are substantially the same as the fuel cell membrane humidifier 200 according to the second embodiment described above, except that (i) the internal space of the mid-case 211 is partitioned into a first space S1 and a second space S2 by partitions 211c, and (ii) the cartridge 212 further includes an inner case 212c. The inner case 212c has openings at each end, and the hollow fiber membrane 212a and the void adjustment tube 215 are inserted therein. The potting portion 212b where the end of the hollow fiber membrane 212a is potted closes the opening of the inner case 212c. As shown in FIG. 7, at least a part of the potting portion 212b can be located outside the inner case 212c, and the protruding member 231b of the gasket assembly 230 can be in close contact with the potting portion 212b. Alternatively, as shown in FIG. 8, the entire potting portion 212b is located inside the inner case 212c, and the protruding member 231b of the gasket assembly 230 can be in close contact with the inner case 212c other than the potting portion 212b. The inner case 212c includes a plurality of holes (hereinafter, "first mesh holes") MH1 arranged in a mesh form for fluid communication with the first space S1 and a plurality of holes (hereinafter, "second mesh holes") MH2 arranged in a mesh form for fluid communication with the second space S2. The exhaust gas that has flowed into the first space S1 of the mid-case 211 through the exhaust gas inlet 211a flows into the inner case 212c through the first mesh hole MH1 and comes into contact with the outer surface of the hollow fiber membrane 212a. Next, the exhaust gas from which moisture has been removed exits into the second space S2 through the second mesh hole MH2, and then is discharged from the mid-case 211 through the exhaust gas outlet 211b. The cartridge 212 provided with such an inner case 212c has the advantage that it can not only be easily assembled to the mid-case 211 but also be easily replaced.

[0024] Next, with reference to FIGS. 9 to 12, a fuel cell membrane humidifier and a modified example thereof according to the third embodiment of the present invention will be described. FIG. 9 is an exploded perspective view showing the fuel cell membrane humidifier according to the third embodiment of the present invention, FIG. 10 is an exploded cross-sectional view showing the fuel cell membrane humidifier according to the third embodiment of the present invention, FIG. 11 is an assembled cross-sectional view showing the fuel cell membrane humidifier according to the third embodiment of the present invention, and FIG. 12 is an assembled cross-sectional view showing a modified example of the fuel cell membrane humidifier according to the third embodiment of the present invention. As shown in FIGS. 9 to 11, the fuel cell humidifier 300 according to the third embodiment of the present invention is substantially the same as the fuel cell humidifier 200 according to the second embodiment described above, except that (i) the humidifying module 210 includes two or more cartridges 212, (ii) the gasket assembly 330 includes two or more holes H into which the cartridges 212 are respectively inserted, (iii) the body member 231a is provided with two or more protruding members 231b formed at one end so as to contact the cartridge potting portion 212b, and (iv) two or more sealing portions 233 are formed so as to bring the cartridge 212 into contact with the packing portion 231 between the cartridge 212 and the packing portion 231.

[0025] A plurality of cartridges 212 each having an inner case 212c are mounted in a mid-case 211 at regular intervals, so that exhaust gas can be uniformly distributed to all the hollow fiber membranes 212a present in the mid-case 211, and only a specific cartridge 212 in which a problem has occurred can be selectively replaced, further reducing the maintenance cost of the fuel cell humidifier 300. On the other hand, as shown in FIG. 12, a modified example 300a of the fuel cell membrane humidifier according to the third embodiment of the present invention is substantially the same as the fuel cell humidifier 300 according to the third embodiment described above, except that the entire potting portion 212b of each cartridge 212 is located in the corresponding inner case 212c, and the protruding member 231b of the gasket assembly 330 is in close contact with the inner case 212c that is not the potting portion 212b. As described above, one embodiment of the present invention has been described. However, those having ordinary knowledge in the technical field can variously modify and change the present invention by adding, changing, deleting, or adding components, etc., within the scope not departing from the idea of the present invention described in the claims, and this can also be said to be included within the scope of the rights of the present invention.

Explanation of Reference Numerals

[0026] 100, 200, 200a, 200b, 300, 300a: Fuel cell membrane humidifier 110, 210: Humidification module 111, 211: Mid-case 111a, 211a: Exhaust gas inlet 111b, 211b: Exhaust gas outlet 211c: Partition wall 212: Cartridge 112, 212a: Hollow fiber membrane 113, 212b: Potting portion 212c: Inner case 115, 215: Gap adjustment tube 120, 220: Cap 230, 330: Gasket assembly 231: Packing portion 231a: Body member 231b: Protruding member 232: Edge portion 233: Sealing portion 234: Reinforcing member

Claims

1. A mid-case, a cap fastened to the mid-case, a plurality of hollow fiber membranes disposed within the mid-case, for humidifying the air by performing moisture exchange between the externally supplied air and the exhaust gas flowing in from a fuel cell stack, a void adjustment tube disposed between the plurality of hollow fiber membranes, formed of a material having a different coefficient of thermal expansion from that of the plurality of hollow fiber membranes, for adjusting the voids between the plurality of hollow fiber membranes according to the temperature of the exhaust gas, comprising: a fuel cell membrane humidifier, characterized in that the coefficient of thermal expansion is a volume expansion coefficient depending on temperature.

2. The void adjustment tube is expanded in a first temperature range and contracted in a second temperature range greater than the first temperature range, and the fuel cell membrane humidifier according to claim 1, comprising a negative thermal expansion material.

3. The void adjustment tube contains bismuth (Bi), and the fuel cell membrane humidifier according to claim 2.

4. The void adjustment tube contains oxides of bismuth (Bi), lanthanum (La), and nickel (Ni), and the fuel cell membrane humidifier according to claim 2.

5. The void adjustment tube contains oxides of bismuth (Bi), iron (Fe), and nickel (Ni), and the fuel cell membrane humidifier according to claim 2.

6. a humidification module including an inner case for housing the plurality of hollow fiber membranes and at least one or more cartridges having a potting portion formed at an end of the inner case, and the fuel cell membrane humidifier according to claim 1.

7. a body member having a hole into which an end of the cartridge is inserted, and a protruding member formed at one end of the body member, contacting the end of the cartridge inserted into the hole, for preventing the fluid within the mid-case from flowing toward the cap side; an edge portion formed at the other end of the body member, formed in a space formed by a groove formed at an end of the mid-case and an end of the cap; a sealing portion formed to contact the cartridge and the packing portion, for preventing the fluid within the mid-case from flowing toward the cap side; a gasket assembly including the above, and the fuel cell membrane humidifier according to claim 6.

8. The body member includes two or more holes into which two or more cartridges can be respectively inserted. The protruding members are provided in two or more numbers and are formed in contact with the respective end portions of the two or more cartridges. The sealing portions are provided in two or more numbers and are formed to contact each of the two or more cartridges and the packing portion. The fuel cell membrane humidifier according to claim 7.

9. The protruding member is in contact with the end portion of the cartridge while pressing it by an elastic force, and airtightly seals the space on the mid-case side and the space on the cap side. The fuel cell membrane humidifier according to claim 7.

10. The edge portion is provided with edge wings protruding in both directions, and the edge wings are interposed while filling a groove formed in the mid-case end portion, and seal the inside and outside of the mid-case, and the mid-case and the cap. The fuel cell membrane humidifier according to claim 7.

11. Each of the packing portion and the edge portion has a first hardness of 30 to 70 Shore A, and further includes a reinforcing member that is formed by being inserted into at least a part of the packing portion and at least a part of the edge portion and has a second hardness higher than the first hardness. The fuel cell membrane humidifier according to claim 7.

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