Fuel Cell Membrane Humidifier

Abstract

The present invention relates to a membrane humidifier for a fuel cell that can seal the gap between an inner case and a mid case that constitute a cartridge and prevent exhaust gas from being bypassed. The membrane humidifier for a fuel cell includes a mid case in which a partition wall that divides an internal space is formed, a first cap fastened to one side of the mid case, a second cap fastened to the other side of the mid case, an inner case arranged within the mid case and accommodating a plurality of hollow fiber membranes therein, a rib protruding from one side of the inner case and contacting one side of the partition wall, a hook protruding from the other side of the inner case and contacting the other side of the partition wall, a first gasket arranged between the first cap and the inner case and transmitting the fastening force between the first cap and the mid case to the rib, and a second gasket arranged between the second cap and the inner case and transmitting the fastening force between the second cap and the mid case to the hook.

Description

[Technical field]

[0001] The present invention relates to a membrane humidifier for a fuel cell, and more specifically, to a membrane humidifier for a fuel cell that can seal the gap between an inner case and a mid case that constitute a cartridge, thereby preventing bypass of exhaust gas. [Background technology]

[0002] A fuel cell is a power generating battery that generates electricity by combining hydrogen and oxygen. Unlike general chemical batteries such as dry batteries and storage batteries, fuel cells can continuously generate electricity as long as hydrogen and oxygen are supplied, and have the advantages of no heat loss and being twice as efficient as an internal combustion engine. In addition, because the chemical energy produced by the combination of hydrogen and oxygen is directly converted into electrical energy, fuel cells emit less polluting substances. Therefore, fuel cells are not only environmentally friendly, but also have the advantage of reducing concerns about resource depletion due to increased energy consumption. Depending on the type of electrolyte used, such fuel cells can be broadly classified into polymer electrolyte membrane fuel cells (PEMFCs), phosphoric acid fuel cells (PAFCs), molten carbonate fuel cells (MCFCs), solid oxide fuel cells (SOFCs), alkaline fuel cells (AFCs), and the like. Although all of these fuel cells operate on the same fundamental principle, they differ in the type of fuel used, operating temperature, catalyst, electrolyte, etc. Among them, polymer electrolyte membrane fuel cells (PEMFCs) are known to be the most promising for use not only in small-scale stationary power generation equipment but also in transportation systems, as they operate at lower temperatures than other fuel cells, have high power density, and can be made compact. One of the most important factors in improving the performance of a polymer electrolyte fuel cell (PEMFC) is to maintain its function by supplying a certain amount of moisture to the polymer electrolyte membrane (PEM or proton exchange membrane) of the membrane electrode assembly (MEA). If the polymer electrolyte membrane dries out, the power generation efficiency drops sharply. There are three methods for humidifying a polymer electrolyte membrane: 1) a bubbler humidification method in which a pressure-resistant container is filled with water and the target gas is passed through a diffuser to supply moisture; 2) a direct injection method in which the amount of moisture required for the fuel cell reaction is calculated and moisture is supplied directly to the gas flow pipe via a solenoid valve; and 3) a humidification membrane method in which moisture is supplied to the gas flow bed using a polymer separation membrane. Among these, the membrane humidification method, which utilizes a membrane that selectively allows only water vapor contained in exhaust gas to pass through and provides water vapor to air supplied to the polymer electrolyte membrane to humidify the polymer electrolyte membrane, is advantageous in that it allows the membrane humidifier to be made lighter and smaller.

[0003] The selectively permeable membrane used in the membrane humidification method is preferably a hollow fiber membrane, which has a large permeation area per unit volume when forming a module. That is, when the hollow fiber membrane is used to manufacture a membrane humidifier, it is possible to highly integrate hollow fiber membranes with a large contact surface area, and it has the advantages that the fuel cell can be sufficiently humidified even with a small capacity, low-cost materials can be used, and the moisture and heat contained in the off-gas discharged at high temperature from the fuel cell can be recovered and reused through the membrane humidifier. FIG. 1 is an exploded perspective view illustrating a membrane humidifier for a fuel cell according to the prior art, and FIG. 2 is a cross-sectional view for explaining problems with the membrane humidifier for a fuel cell according to the prior art. Referring to Figures 1 and 2, a conventional fuel cell membrane humidifier 10 includes a humidification module 11 in which moisture exchange occurs between air supplied from the outside and exhaust gas discharged from a fuel cell stack (not shown), and caps 12 attached to both ends of the humidification module 11. One of the caps 12 supplies air supplied from the outside to the humidification module 11, and the other supplies air humidified by the humidification module 11 to the fuel cell stack. The humidification module 11 includes a mid-case 11a having an off-gas inlet 11b and an off-gas outlet 11c, and at least one cartridge 20 disposed in the mid-case 11a. In the drawings, one cartridge is illustrated. The cartridge 20 includes an inner case 23, and inside the inner case 23, a number of hollow fiber membranes 21 and a potting portion 22 for fixing both ends of the bundle of hollow fiber membranes 21 are formed. The potting portion 22 is generally formed by hardening a liquid polymer such as a liquid polyurethane resin through a casting method.

[0004] A resin layer 11e is formed between the cartridge 20 and the mid case 11a. The resin layer 11e fixes the cartridge 20 to the mid case 11a and separates the internal space of the cap 12 from the internal space of the mid case 11a. The internal space of the mid case 11a is divided into a first space S1 and a second space S2 by a partition wall 11d. The inner case 23 has first mesh holes MH1 arranged in a mesh shape for fluid communication with the first space S1, and has second mesh holes MH2 arranged in a mesh shape for fluid communication with the second space S2. The exhaust gas that flows into the first space S1 of the mid case 11a through the exhaust gas inlet 11b flows into the inner case 23 through the first mesh hole portion MH1 and comes into contact with the outer surface of the hollow fiber membrane 21. The exhaust gas from which moisture has been removed subsequently flows into the second space S2 through the second mesh hole portion MH2, and is then discharged from the mid case 11a through the exhaust gas outlet 11c. The cartridge 20 including such an inner case 23 has the advantage that it can be easily installed in the mid case 11a as well as easily replaced. 2, the inner case 23 has a rib 25 that contacts one side of the partition 11d and a hook 24 that contacts the other side of the partition 11d. The hook 24 has an inclined surface. When the cartridge 20 is inserted into the mid case 11a from the left to right direction in the drawing with the cap 12 and the mid case 11a separated, the inclined surface of the hook 24 contacts the partition 11d and is inserted between the partitions in a tight fit manner. Then, as the cartridge 20 continues to be inserted, if the rib 25 contacts the partition 11d, it is fixed without being inserted any further. That is, the hooks 24 and the ribs 25 of the cartridge 20 sandwich the partition wall 11d and are fixed to one surface and the other surface of the partition wall 11d, so that the cartridge 20 can be fixed within the mid case 11a. In this case, the distance between the hook 24 and the rib 25 and the width of the partition 11d must be substantially the same. Otherwise, the exhaust gas flowing in through the exhaust gas inlet 11b passes through the gap between the rib 25 and the partition 11d and the gap between the hook 24 and the partition 11d, and is discharged to the exhaust gas outlet 11c. In other words, the exhaust gas that should be used for humidification is bypassed and discharged to the outside without being humidified (see the symbol "BF" in FIG. 2). However, due to incorrect assembly or dimensional tolerances, the distance between the hook 24 and the rib 25 and the width of the partition wall 11d may differ, which may result in bypassed exhaust gas and reduced humidification efficiency. Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a membrane humidifier for a fuel cell that can seal the gap between an inner case and a mid case that constitute a cartridge, and prevent exhaust gas from being bypassed. [Means for solving the problem]

[0006] The membrane humidifier for a fuel cell according to an embodiment of the present invention comprises: The cap includes a mid case having a partition wall that divides an internal space, a cap fastened to the mid case, an inner case disposed within the mid case and housing a plurality of hollow fiber membranes therein, a rib protruding from one side of the inner case and contacting one side of the partition wall, and a gasket disposed between the cap and the inner case, transmitting the fastening force between the cap and the mid case to the rib and sealing the gap between the inner case and the partition wall. In addition, the membrane humidifier of the fuel cell according to the embodiment of the present invention comprises: The cap includes a mid case having a partition wall that divides an internal space, a cap fastened to the mid case, an inner case disposed within the mid case and housing a plurality of hollow fiber membranes therein, a hook protruding from the other side of the inner case and contacting the other side of the partition wall, and a gasket disposed between the cap and the inner case, transmitting the fastening force between the cap and the mid case to the hook and sealing the gap between the inner case and the partition wall. In a membrane humidifier for a fuel cell according to an embodiment of the present invention, the gasket also includes an inner case interface where the gasket and the inner case contact, a cap interface where the gasket and the cap contact, and an insertion protrusion inserted between an end of the cap and an end of the mid case. In the membrane humidifier of the fuel cell according to the embodiment of the present invention, the bottom surface of the cap in contact with the cap interface is also formed to have a size corresponding to the cap interface. In the membrane humidifier for a fuel cell according to an embodiment of the present invention, the rib may have a closed curve shape surrounding the outer surface of the inner case. In the membrane humidifier for a fuel cell according to an embodiment of the present invention, the hook may have a closed curve shape surrounding the outer surface of the inner case.

[0007] In addition, the membrane humidifier of the fuel cell according to the embodiment of the present invention comprises: the first cap is fastened to one side of the midcase; and the second cap is fastened to the other side of the midcase. The inner case is disposed within the midcase and houses a plurality of hollow fiber membranes therein. The inner case protrudes from one side of the inner case and contacts one side of the partition. A hook protrudes from the other side of the inner case and contacts the other side of the partition. A first gasket is disposed between the first cap and the inner case and transmits a fastening force between the first cap and the midcase to the rib. A second gasket is disposed between the second cap and the inner case and transmits a fastening force between the second cap and the midcase to the hook. In the membrane humidifier for a fuel cell according to an embodiment of the present invention, the first gasket and the second gasket may have different sizes. In the membrane humidifier of the fuel cell according to an embodiment of the present invention, the rib has a closed curve shape surrounding the outer surface of the inner case, and if the hook does not have a closed curve shape, the size of the first gasket may be larger than the size of the second gasket. In the membrane humidifier of the fuel cell according to an embodiment of the present invention, the hook has a closed curve shape surrounding the outer surface of the inner case, and if the rib does not have a closed curve shape, the size of the second gasket may be larger than the size of the first gasket. Effect of the Invention

[0008] According to an embodiment of the present invention, the gap between the inner case and the mid case that constitute the cartridge can be sealed, thereby preventing exhaust gas from being bypassed. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is an exploded perspective view illustrating a membrane humidifier for a fuel cell according to the prior art; [Diagram 2] FIG. 1 is a cross-sectional view for explaining a problem of a membrane humidifier for a fuel cell according to the prior art. [Diagram 3] 1 is a cross-sectional view illustrating a membrane humidifier of a fuel cell according to an embodiment of the present invention; [Figure 4] 1 is a cross-sectional view illustrating a gasket according to an embodiment of the present invention; [Diagram 5] 5A to 5C are cross-sectional views illustrating different types of partition walls in a membrane humidifier of a fuel cell according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Although the present invention can be modified in various ways and has various embodiments, specific embodiments are illustrated and described in detail by detailed description. However, it should be understood that they do not limit the present invention to the specific embodiments, but include all modifications, equivalents, or alternatives within the spirit and technical scope of the present invention. The terms used in the present invention are merely used to describe a specific embodiment and are not intended to limit the present invention. A singular expression includes a plural expression unless the context clearly indicates otherwise. In the present invention, the terms "comprise" or "have" specify the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, and should be understood not to preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof. Hereinafter, a membrane humidifier for a fuel cell according to an embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a cross-sectional view illustrating a membrane humidifier of a fuel cell according to one embodiment of the present invention, FIG. 4 is a cross-sectional view illustrating a gasket according to one embodiment of the present invention, and FIG. 5 is a cross-sectional view illustrating a membrane humidifier of a fuel cell according to one embodiment of the present invention in which the partition wall is embodied in a different shape. As shown in FIG. 3, a fuel cell membrane humidifier 100 according to one embodiment of the present invention includes a humidification module 110, a cap 120, and a gasket . The humidification module 110 exchanges moisture between air supplied from the outside and exhaust gas discharged from a fuel cell stack (not shown). Caps 120 are coupled to both ends of the humidification module 110. One of the caps 120 supplies air supplied from the outside to the humidification module 110, and the other supplies 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 112 and an exhaust gas outlet 113 , and at least one cartridge 20 disposed within the mid-case 111 . Here, it goes without saying that, depending on the design, one of the caps 120 can supply the exhaust gas to the humidification module 110 and cause it to flow inside the hollow fiber membrane, and the other can discharge the exhaust gas after moisture exchange to the outside. In this case, external air can be introduced through either the exhaust gas inlet 112 or the exhaust gas outlet 113, and air humidified by the humidification module 110 can be supplied to the fuel cell stack through the remaining one. The flow direction of the external air and the flow direction of the exhaust gas can be the same direction or opposite directions. The mid case 111 and the cap 120 may each be independently formed of a hard plastic or metal and have a circular or polygonal width cross section. The circle includes an ellipse, and the polygon includes a polygon with rounded corners. For example, the hard plastic may be polycarbonate, polyamide (PA), polyphthalamide (PPA), polypropylene (PP), etc. The internal space of the mid case 111 is also divided into a first space S1 and a second space S2 by a partition wall 114. The cartridge 20 includes a number of hollow fiber membranes 21 , a potting portion 22 , an inner case 23 , hooks 24 , and ribs 25 .

[0011] The hollow fiber membrane 21 also includes a polymer membrane formed from 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 or more of them. The potting portion 22 fixes an end of the hollow fiber membrane 21. The potting portion 22 can be formed by hardening a liquid resin such as a liquid polyurethane resin through a casting method such as dip potting or centrifugal potting. The inner case 23 has an opening at each end and accommodates a number of hollow fiber membranes 21 therein. The potting portion 22, to which the ends of the hollow fiber membranes 21 are potted, closes the opening of the inner case 23. The inner case 23 has a first mesh hole portion MH1 arranged in a mesh shape for fluid communication with the first space S1, and a second mesh hole portion MH2 arranged in a mesh shape for fluid communication with the second space S2. The exhaust gas that flows into the first space S1 of the mid case 111 through the exhaust gas inlet 112 flows into the inner case 23 through the first mesh hole portion MH1 and comes into contact with the outer surface of the hollow fiber membrane 21. The exhaust gas from which moisture has been removed then flows through the second mesh hole portion MH2 into the second space S2, and is then discharged from the mid case 111 through the exhaust gas outlet 113. A gasket 130 is provided between the cap 120 and the cartridge 20. Specifically, the gasket 130 is provided between the inner case 23 and the cap 120, which constitute the cartridge 20, and is pressurized by the cap 120. The gasket 130a transmits the fastening force between the cap 120 and the mid case 111 to the rib 25, which causes the rib 25 to seal the gap between the inner case 23 and the partition wall 114. Similarly, the gasket 130 b transmits the fastening force between the cap 120 and the mid case 111 to the hook 24 , causing the hook 24 to seal the gap between the inner case 23 and the partition wall 114 . In the following description, the sealing by the rib 25 will be mainly described, but the case where the sealing is performed by the hook 24 is not excluded. Whether the hook 24 or the rib 25 seals the gap is also determined by the shape of the hook 24 or the rib 25. When the rib 25 has a closed curve shape surrounding the outer surface periphery of the inner case 23, the rib 25 can seal the gap, and when the hook 24 has a closed curve shape surrounding the outer surface periphery of the inner case 23, the hook 24 can seal the gap.

[0012] The gasket 130 includes an inner case interface 131, a cap interface 132, and an insertion protrusion 133, and may be formed in the shape of a single closed curve as shown in FIG. The inner case interface 131 is a surface where the gasket 130 and the inner case 23 come into contact with each other, and may have a single closed curve shape corresponding to the cross-sectional shape of the inner case 23. The cap interface 132 is a surface where the gasket 130 and the cap 120 come into contact with each other, and may have a single closed curve shape corresponding to the cross-sectional shape of the cap 120. The insertion protrusion 133 is inserted between an end of the cap 120 and an end of the mid case 111, and seals the space inside the cap 120 and the space inside the mid case 111 while being pressurized when the cap 120 and the mid case 111 are fastened and assembled. The gasket 130 is made of a rubber or plastic material having a predetermined hardness. After being placed between the cap 120 and the inner case 23, when the cap 120 and the mid case 111 are fastened together using bolts and nuts, the gasket 130 is compressed by the pressure applied by the cap 120 and the mid case 111, and can transmit the fastening force between the cap 120 and the mid case 111 to the inner case 23 and a rib 25 protruding from one side of the inner case. The fastening force (compression pressure or repulsion force) received by the gasket 130 is transmitted to the rib 25 via the inner case 23, and the rib 25 applies the force in the direction of the partition wall 114. Therefore, even if there is a dimensional tolerance during manufacturing, the rib 25 can seal the gap between the inner case 23 and the partition wall 114. As a result, it is possible to prevent exhaust gas from bypassing through the gap. Here, the "dimensional tolerance" is used to mean all cases in which the distance between the hook 24 and the rib 25 and the width size of the partition wall 114 differ during the manufacturing process. In order to make the fastening force transmission more effective, the bottom surface 122 of the cap 120 that contacts the cap interface 132 is also formed to a size corresponding to that of the cap interface 132 . Even if the first gasket 130a on the rib 25 side and the second gasket 130b on the hook 24 side are formed to have the same hardness and dimensions, the fastening force received by the gasket 130 can be transmitted to the rib 25. However, since the second gasket 130b on the hook 24 side also transmits a fastening force to the hook 24, there is a concern that the fastening forces on both sides may be offset. For this reason, in the present invention, the first gasket 130a on the rib 25 side and the second gasket 130b on the hook 24 side can be made to have different sizes. Here, the size of the gaskets 130a and 130b means the size of the gasket heads 134a and 134b, which are the gaps between the gaskets and the cartridge 20 (see L1 and L2 in FIG. 3).

[0013] Referring again to FIG. 3, in consideration of the assembly sequence of the membrane humidifier, first, the right cap 120 is fastened to the mid case 111. At that time, the second gasket 130b is inserted into the right cap 120 and the mid case 111. After that, the cartridge 20 is inserted into the mid case 111. At that time, the hook 24 having an inclined surface is inserted first, and the rib 25 is inserted afterwards. The hook 24 and the rib 25 sandwich the partition wall 114 and are fixed to one surface and the other surface of the partition wall 114. Next, the first gasket 130a is disposed on the ends of the inner case 23 and the mid case 111, and then the left cap 120 is fastened to the mid case 111. At that time, the fastening force between the left cap 120 and the mid case 111 is transmitted to the rib 25. Also, at that time, the fastening force between the right cap 120 and the mid case 111 is transmitted to the hook 24. In this situation, if the first gasket 130a on the rib 25 side and the second gasket 130b on the hook 24 side have different sizes, the fastening force of one side (or the repulsive force by the gasket) becomes more dominant, and one of the rib 25 or hook 24 can seal the gap between the inner case 23 and the partition wall 114. Although the first gasket 130a and the second gasket 130b have different sizes, the size can be determined depending on the shape of the hooks 24 or the ribs 25. When the rib 25 has a closed curve shape surrounding the outer surface of the inner case 23, the rib 25 can seal the gap between the inner case 23 and the partition wall 114, so it is desirable that the first gasket 130a on the rib 25 side be formed larger than the second gasket 130b on the hook 24 side. Similarly, when the hook 24 has a closed curve shape surrounding the outer surface of the inner case 23, it is desirable that the second gasket 130b on the hook 24 side be formed even larger, since the hook 24 can seal the gap between the inner case 23 and the partition wall 114.

[0014] When the hooks 24 and the ribs 25 each have a closed curved shape that surrounds the outer surface periphery of the inner case 23, the first gasket 130a and the second gasket 130b may be formed to have different sizes. Depending on the design, the partition 114 may be formed in a shape as shown in Fig. 5. Referring to Fig. 5, the partition 114 may be formed in such a way that the central portion of the mid case 111 is recessed inward. Although one embodiment of the present invention has been described above, a person having ordinary knowledge in the art may modify and change the present invention in various ways by adding, changing, deleting or adding components within the scope of the concept of the present invention described in the claims, and these modifications and changes are also within the scope of the rights of the present invention.

Claims

1. A mid-case having a partition wall that divides the internal space; a first cap fastened to one side of the mid case; A second cap fastened to the other side of the mid case; an inner case disposed in the mid case and accommodating a plurality of hollow fiber membranes therein; a rib protruding from one side of the inner case and contacting one surface of the partition wall; a hook provided on the other side of the inner case and in contact with the other surface of the partition wall; a first gasket disposed between the first cap and the inner case and configured to transmit a fastening force between the first cap and the mid case to the rib; a second gasket disposed between the second cap and the inner case and configured to transmit a fastening force between the second cap and the mid case to the hook; A membrane humidifier for a fuel cell, wherein the rib has a closed curve shape surrounding the outer surface periphery of the inner case, and when the hook does not have a closed curve shape, the size of the first gasket is larger than the size of the second gasket.

2. A mid-case having a partition wall that divides an internal space; a first cap fastened to one side of the mid case; A second cap fastened to the other side of the mid case; an inner case disposed in the mid case and accommodating a plurality of hollow fiber membranes therein; a rib protruding from one side of the inner case and contacting one surface of the partition wall; a hook provided on the other side of the inner case and in contact with the other surface of the partition wall; a first gasket disposed between the first cap and the inner case and configured to transmit a fastening force between the first cap and the mid case to the rib; a second gasket disposed between the second cap and the inner case and configured to transmit a fastening force between the second cap and the mid case to the hook; A membrane humidifier for a fuel cell, wherein the hook has a closed curve shape surrounding the outer surface periphery of the inner case, and when the rib does not have a closed curve shape, the size of the second gasket is larger than the size of the first gasket.

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