Mid-case and fuel cell humidifier

Abstract

The present invention relates to a mid-case of a humidifier for a fuel cell and a humidifier for a fuel cell, the mid-case including: a mid-body housing at least one cartridge including a plurality of hollow fiber membranes; a partition wall portion disposed inside the mid-body dividing the interior of the mid-body into an inflow space into which a first gas flows and an outflow space through which the first gas flows; and a bypass hole formed through the partition wall portion to allow a portion of the first gas flowing into the inflow space to bypass the cartridge and flow into the outflow space.

Description

Technical Field

[0001] The present invention relates to a fuel cell humidifier for supplying a humidified gas to a fuel cell.

Background Art

[0002] Unlike 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 has the advantage of being about twice as efficient as an internal combustion engine because there is no heat loss. In addition, since chemical energy generated by the combination of hydrogen and oxygen is directly converted into electrical energy, there is little emission of pollutants. Therefore, fuel cells have the advantage of being environmentally friendly and being able to reduce concerns about resource depletion associated with increasing energy consumption. Such fuel cells can be broadly classified into Polymer Electrolyte Membrane Fuel Cell (PEMFC), Phosphoric Acid Fuel Cell (PAFC), Molten Carbonate Fuel Cell (MCFC), Solid Oxide Fuel Cell (SOFC), and Alkaline Fuel Cell (AFC) according to the type of electrolyte used. Each of these fuel cells operates based on basically 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 to be the most promising not only as a small-scale stationary power generation device but also as a transportation system because it operates at a lower temperature compared to other fuel cells and has a large output density and can be miniaturized. One of the most important factors in improving the performance of polymer electrolyte fuel cells (PEMFCs) is maintaining a certain level of moisture content in the polymer electrolyte membrane (PEM) of the membrane electrode assembly (MEA). This is because the power generation efficiency drops sharply when the polymer electrolyte membrane dries out. Methods for humidifying polymer electrolyte membranes include: 1) the bubbler humidification method, which involves filling a pressure vessel with water and then passing the target gas through a diffuser to supply moisture; 2) the direct injection method, which calculates the amount of moisture required for the fuel cell reaction and supplies moisture directly to the gas flow pipe through a solenoid valve; and 3) the humidification membrane method, which uses a polymer separation membrane to supply moisture to the gas fluid bed.

[0003] Among these methods, the membrane humidification method, which uses a membrane that selectively allows only water vapor contained in the exhaust gas to pass through, and provides water vapor to the air supplied to the polymer electrolyte membrane, is advantageous in that it allows for a lighter and more compact humidifier. When forming modules, hollow fiber membranes with a large permeable area per unit volume are preferred as selective permeable membranes used in membrane humidification systems. In other words, when manufacturing humidifiers using hollow fiber membranes, it is possible to integrate a large number of hollow fiber membranes with a large contact surface area, which allows for sufficient humidification of fuel cells even in small capacities, enables the use of low-cost materials, and has the advantage of recovering moisture and heat contained in the exhaust gas (off-gas) discharged at high temperatures from fuel cells and reusing it through the humidifier. Figure 1 is a schematic exploded perspective view of a typical fuel cell humidifier. As illustrated in Figure 1, a typical membrane humidifier (100) includes a humidification module (110) in which moisture exchange takes place between air supplied from the outside and exhaust gas discharged from a fuel cell stack (not shown), and caps (120) coupled to both ends of the humidification module (110). One of the caps (120) transmits air supplied from the outside to the humidification module (110), and the other transmits the air humidified by the humidification module (110) to the fuel cell stack. The humidification module (110) includes a mid-case (111) having an off-gas inlet (111a) and an off-gas outlet (111b), and a plurality of hollow fiber membranes (112) within the mid-case (111). Both ends of the hollow fiber membranes (112) are potted in a fixed layer (113). The fixed layer (113) is generally formed by curing a liquid polymer, such as liquid polyurethane resin, using a casting method. The fixed layer (113) to which the ends of the hollow fiber membranes (112) are potted, and the resin layer (114) between the fixed layer (113) and the mid-case (111) isolate the internal space of the cap (120) from the internal space of the mid-case (111). Similar to the fixed layer (113), the resin layer (114) is generally formed by curing a liquid polymer, such as liquid polyurethane resin, using a casting method. Air supplied from the outside flows along the hollow of the hollow fiber membrane (112). Exhaust gas that flows into the mid-case (111) through the exhaust gas moist gas inlet (111a) comes into contact with the outer surface of the hollow fiber membrane (112) and then flows out of the mid-case (111) through the exhaust gas moist 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 that was flowing along the hollow of the hollow fiber membrane (112).

[0004] In this case, conventionally, the shell differential pressure, which corresponds to the internal pressure of the mid-case (111), may increase between the time the exhaust gas flows into the mid-case (111) and the time it flows out of the mid-case (111). When the shell differential pressure increases in this way, problems arise such as an increase in power consumption and a decrease in the efficiency of the fuel cell system. This problem is further exacerbated as fuel cell humidifiers become smaller. [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] The present invention was devised to solve the aforementioned problems and aims to provide a mid-case for a fuel cell humidifier and a fuel cell humidifier that can reduce shell differential pressure. [Means for solving the problem]

[0006] To solve the aforementioned problems, the present invention may include the following configuration. The mid-case of the fuel cell humidifier according to the present invention is provided in a fuel cell humidifier that includes a humidifying module for humidifying dry gas supplied to a fuel cell stack using a humidifying gas, a first cap coupled to one end of the humidifying module, and a second cap coupled to the other end of the humidifying module, and may include: a mid-body housing at least one cartridge containing a plurality of hollow fiber membranes; a partition wall disposed inside the mid-body and dividing the inside of the mid-body into an inlet space into which a first gas flows and an outlet space into which the first gas flows out; and a bypass hole formed through the partition wall so that a portion of the first gas flowing into the inlet space bypasses the cartridge and flows into the outlet space. The fuel cell humidifier according to the present invention may include a humidification module for humidifying dry gas supplied to a fuel cell stack using a humidified gas; a first cap coupled to one end of the humidification module; and a second cap coupled to the other end of the humidification module. The humidification module may include a mid-case with both ends open, and at least one cartridge containing a plurality of hollow fiber membranes. The mid-case may include a mid-body in which the cartridge is housed; a partition wall disposed inside the mid-body and dividing the inside of the mid-body into an inlet space into which a first gas flows and an outlet space into which the first gas flows out; and a bypass hole formed through the partition wall so that a portion of the first gas flowing into the inlet space bypasses the cartridge and flows into the outlet space. [Effects of the Invention]

[0007] The present invention is embodied in which a portion of the first gas flowing into the inlet space bypasses the cartridge through a bypass hole and flows into the outlet space. As a result, the present invention can reduce the shell differential pressure using the bypass hole, and thus contribute to improving the efficiency of the fuel cell system. This invention prevents excessive increases in shell differential pressure by using bypass holes, even when the size of the mid-case is reduced. Therefore, by miniaturizing and implementing this invention, the versatility of the invention can be improved, making it applicable to a variety of uses such as hydrogen fuel cell vehicles. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic exploded perspective view of a typical fuel cell humidifier. [Figure 2] This is a schematic exploded perspective view of a fuel cell humidifier according to the present invention. [Figure 3] This is a schematic exploded cross-sectional view of the fuel cell humidifier according to the present invention, shown with reference to line II in Figure 2. [Figure 4]This is a schematic coupled cross-sectional view of the fuel cell humidifier according to the present invention, shown with respect to line II in Figure 2. [Figure 5] This is a schematic plan view of the cartridge of a fuel cell humidifier according to the present invention. [Figure 6] This is a schematic plan view of the cartridge of a fuel cell humidifier according to the present invention. [Figure 7] This is a schematic side cross-sectional view showing how the inlet space and outlet space are partitioned by a partition wall in the mid-case of a fuel cell humidifier according to the present invention. [Figure 8] This is a schematic cross-sectional view taken with reference to line II-II in Figure 7. [Figure 9] This is a schematic side cross-sectional view showing how a bypass hole is formed in the partition wall portion of the mid-case of a fuel cell humidifier according to the present invention. [Figure 10] This is a schematic cross-sectional view of the mid-case of a fuel cell humidifier according to a modified embodiment of the present invention, shown with reference to line II-II in Figure 7. [Figure 11] This is an experimental result in which the humidification efficiency and shell differential pressure were measured while keeping the cross-sectional area of ​​the inner surface of the compartment fixed and only changing the cross-sectional area of ​​the bypass hole. [Modes for carrying out the invention]

[0009] Hereinafter, embodiments of the fuel cell humidifier according to the present invention will be described in detail with reference to the attached drawings. The mid-case of the fuel cell humidifier according to the present invention can be included in the fuel cell humidifier according to the present invention, and will be described together with the embodiments of the fuel cell humidifier according to the present invention. On the other hand, in Figures 7 and 9, the hollow fiber membrane is simply shown by hatching, and the inner case is omitted. Referring to Figures 2 to 4, the fuel cell humidifier (1) according to the present invention humidifies dry gas supplied to a fuel cell stack (not shown) using a humid gas. The humid gas may be discharged from the fuel cell stack. The dry gas may be fuel gas or air. The dry gas can be supplied to the fuel cell stack after being humidified by the humid gas. The fuel cell humidifier (1) according to the present invention includes a humidification module (2) for humidifying the dry gas, a first cap (3) coupled to one end of the humidification module (2), and a second cap (4) coupled to the other end of the humidification module (2). Referring to Figures 2 to 4, the humidification module (2) humidifies dry gas. The first cap (3) can be connected to one end of the humidification module (2). The second cap (4) can be connected to the other end of the humidification module (2). The humidification module (2) can supply humidified dry gas to the fuel cell stack using the first gas and the second gas. When the first gas is dry gas, the second gas may be a humid gas. In this case, the first gas can be supplied to the fuel cell stack after being humidified by the second gas. When the first gas is a humid gas, the second gas may be dry gas. In this case, the second gas can be supplied to the fuel cell stack after being humidified by the first gas. The humidification module (2) includes a mid-case (21) and at least one cartridge (22).

[0010] The mid-case (21) is into which the cartridge (22) is coupled. The cartridge (22) can be placed inside the mid-case (21). The mid-case (21) is open at both ends. In this case, a housing hole (211) can be formed in the mid-case (21). The housing hole (211) can be formed to penetrate the mid-case (21) in the first axial direction (X-axis direction). At least one cartridge (22) can be placed in the housing hole (211). The mid-case (21) may include a mid-body (210). The mid-body (210) houses the cartridge (22). The cartridge (22) can be housed in the mid-body (210) by being positioned inside the mid-body (210). The mid-body (210) can house at least one cartridge (22). The housing hole (211) may be formed to penetrate the mid-body (210) in the first axial direction (X-axis direction). A first gas inlet (212) and a first gas outlet (213) can be formed in the mid-case (21). The first gas inlet (212) allows the first gas to flow into the mid-body (210). The first gas outlet (213) allows the first gas to flow out from the mid-body (210). The first gas outlet (213) and the first gas inlet (212) can each protrude from the mid-body (210). The cartridge (22) is disposed inside the mid-case (21). The cartridge (22) includes a plurality of hollow fiber membranes (221). The hollow fiber membranes (221) can be coupled to the cartridge (22) to be modularized. Thus, through the step of coupling the cartridge (22) to the mid-case (21), the hollow fiber membranes (221) can be installed inside the mid-case (21). Therefore, the humidifier (1) for a fuel cell according to the present invention can improve the ease of installation work, separation work, and replacement work for the hollow fiber membranes (221).

[0011] The cartridge (22) can include an inner case (222). The inner case (222) has openings at both ends and contains the hollow fiber membranes (221). The hollow fiber membranes (221) can be disposed inside the inner case (222) to be modularized. The hollow fiber membranes (221) may 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 two or more of these. The cartridge (22) may include a first fixing layer (223). The first fixing layer (223) fixes one end of the hollow fiber membrane (221). The first fixing layer (223) can close an opening formed at one end of the inner case (222). In this case, the first fixing layer (223) can be formed so as not to block the hollow of the hollow fiber membrane (221). The first fixing layer (223) can be formed by curing a liquid resin, such as liquid polyurethane resin, through a casting process. The first fixing layer (223) may be partially located inside the inner case (222) and partially protruding outside the inner case (222). The first fixing layer (223) can also fix one end of the hollow fiber membrane (221) to the inner case (222). The cartridge (22) may include a second fixing layer (224). The second fixing layer (224) fixes the other end of the hollow fiber membrane (221). The second fixing layer (224) can close an opening formed at the other end of the inner case (222). In this case, the second fixing layer (224) can be formed so as not to block the hollow of the hollow fiber membrane (221). The second fixing layer (224) can be formed by curing a liquid resin, such as liquid polyurethane resin, through a casting process. The second fixing layer (224) may be partially located inside the inner case (222) and partially protruding outside the inner case (222). The second fixing layer (224) can also fix the other end of the hollow fiber membrane (221) to the inner case (222). Since the second fixed layer (224) and the first fixed layer (223) are formed in such a way that they do not block the hollow of the hollow fiber membrane (221), the second gas can be supplied to the hollow of the hollow fiber membrane (221) without being obstructed by the second fixed layer (224) and the first fixed layer (223), and can flow out of the hollow of the hollow fiber membrane (221) without being obstructed by the second fixed layer (224) and the first fixed layer (223). Referring to FIGS. 2 to 6, the cartridge (22) may include a second gas inlet (225) and a second gas outlet (226).

[0012] The second gas inlet (225) is formed in the inner case (222). The second gas inlet (225) can be formed on one side of the inner case (222). One side of the inner case (222) can be arranged to face any one of the side walls of the mid body (210). The second gas inlet (225) can allow the first gas to flow into the inner case (222). The second gas inlet (225) can be formed to penetrate the inner case (222). As shown in FIG. 5, the second gas inlet (225) can be embodied by a single through hole penetrating the inner case (222). As shown in FIG. 6, the second gas inlet (225) can also be embodied by a plurality of through holes penetrating the inner case (222). In this case, the second gas inlet (225) can include a plurality of inflow windows (225a) formed to penetrate different parts of the inner case (222). The inflow windows (225a) can be arranged to be spaced apart from each other along the first axial direction (X-axis direction) and the second axial direction (Y-axis direction) to form a matrix form. The second axial direction (Y-axis direction) is an axial direction perpendicular to the first axial direction (X-axis direction). The second gas outlet (226) is formed in the inner case (222). The second gas outlet (226) can be formed on one side of the inner case (222). The second gas outlet (226) can allow the first gas to flow out from inside the inner case (222). The second gas outlet (226) can be formed by penetrating the inner case (222). As shown in Figure 5, the second gas outlet (226) can be represented by a single through-hole penetrating the inner case (222). As shown in Figure 6, the second gas outlet (226) can also be represented by a plurality of through-holes penetrating the inner case (222). In this case, the second gas outlet (226) can include a plurality of outlet windows (226a) formed to penetrate different parts of the inner case (222). The outflow windows (226a) can be arranged in a matrix configuration, spaced apart from each other along the first axial direction (X-axis direction) and the second axial direction (Y-axis direction). The second gas outlet (226) and the second gas inlet (225) can be positioned at locations spaced apart from each other along the first axial direction (X-axis direction).

[0013] If the first gas is a humid gas, the first gas is supplied through the first gas inlet (212) between the inner surface of the mid-case (21) and the outer surface of the cartridge (22), and is supplied into the interior of the cartridge (22) through the second gas inlet (225) and can come into contact with the outer surface of the hollow fiber membrane (221). In this process, moisture contained in the first gas permeates through the hollow fiber membrane (221), thereby humidifying the second gas that was flowing along the hollow of the hollow fiber membrane (221). After the humidified second gas flows out of the hollow fiber membrane (221), it can be supplied to the fuel cell stack through the first cap (3) or the second cap (4). The first gas, after humidifying the second gas, can flow out through the second gas outlet (226) between the outer surface of the cartridge (22) and the inner surface of the mid-case (21), and can flow out to the outside of the mid-case (21) through the first gas outlet (213). In this case, the first gas may be the exhaust gas (off-gas) discharged from the fuel cell stack. If the first gas is a dry gas, the first gas is supplied through the first gas inlet (212) between the inner surface of the mid-case (21) and the outer surface of the cartridge (22), and supplied to the interior of the cartridge (22) through the second gas inlet (225), and can come into contact with the outer surface of the hollow fiber membrane (221). In this process, moisture from the second gas flowing along the hollow of the hollow fiber membrane (221) permeates through the hollow fiber membrane (221), thereby humidifying the first gas that has flowed into the interior of the cartridge (22). The humidified first gas flows out through the second gas outlet (226) between the outer surface of the cartridge (22) and the inner surface of the mid-case (21), and flows out to the outside of the mid-case (21) through the first gas outlet (213), after which it can be supplied to the fuel cell stack. The second gas, after humidifying the first gas, can be discharged to the outside through the first cap (3) or the second cap (4) after flowing out of the hollow fiber membrane (221). In this case, the second gas may be the exhaust gas (off-gas) discharged from the fuel cell stack.

[0014] The humidification module (2) may include a plurality of packing members (23, 23'). The packing members (23, 23') seal the space between the cartridge (22) and the mid-case (21) to prevent the first gas and the second gas from directly mixing. The packing members (23, 23') can be inserted between the cartridge (22) and the mid-case (21). In this case, the cartridge (22) can be inserted into the first through holes (23a, 23a') formed in the packing members (23, 23'). The packing members (23, 23') can be placed at both ends of the cartridge (22). Although not shown, instead of the packing members (23, 23'), a resin layer can also be formed at both ends of the cartridge (22). The resin layer can be formed by curing a liquid polymer such as liquid polyurethane resin by a casting method. Referring to Figures 2 to 4, the first cap (3) is coupled to one end of the humidification module (2). The space between the first cap (3) and the cartridge (22) can be sealed from the space between the cartridge (22) and the mid-case (21) by the packing member (23) or resin layer. The first cap (3) may include a first port (31). The first port (31) is for the flow of the second gas. The first port (31) can communicate with the hollow fiber membrane (221). As a result, in the process of the second gas flowing between the first cap (3) and the hollow fiber membrane (221), the second gas can flow in or out through the first port (31). Referring to Figures 2 to 4, the second cap (4) is coupled to the other end of the humidification module (2). The second cap (4) can be coupled to the other end of the humidification module (2) at a position separated from the first cap (3) along the first axial direction (X-axis direction). The space between the second cap (4) and the cartridge (22) can be sealed from the space between the cartridge (22) and the mid-case (21) by the packing member (23') or the resin layer. The second cap (4) may include a second port (41). The second port (41) is for the flow of the second gas. The second port (41) can communicate with the hollow fiber membrane (221). As a result, in the process of the second gas flowing between the second cap (4) and the hollow fiber membrane (221), the second gas can flow in or out through the second port (41). When the second gas flows in through the second port (41), the second gas can flow out through the first port (31). In this case, the second gas can exchange moisture with the first gas as it passes sequentially through the second cap (4), the hollow fiber membrane (221), and the first cap (3). When the second gas flows out through the second port (41), the second gas can flow in through the first port (31). In this case, the second gas can exchange moisture with the first gas as it passes sequentially through the first cap (3), the hollow fiber membrane (221), and the second cap (4).

[0015] Here, the fuel cell humidifier (1) according to the present invention can be implemented to prevent an excessive increase in the shell differential pressure, which corresponds to the internal pressure of the mid-case (21), between the time the first gas flows into the mid-case (21) through the first gas inlet (212) and the time it flows out of the mid-case (21) through the first gas outlet (213). For this reason, the mid-case (21) can be implemented as follows. Referring to Figures 2 to 8, the mid-case (21) can include a partition wall (214). The partition wall (214) is located inside the mid-body (210). The partition wall (214) can divide the inside of the mid-body (210) into an inlet space (214a) and an outlet space (214b). The inlet space (214a) is the space into which the first gas flows and can communicate with the first gas inlet (212). With respect to the first axial direction (X-axis direction), the inlet space (214a) can be located between the packing member (23) and the partition wall (214). The outlet space (214b) is the space into which the first gas flows out and can communicate with the first gas outlet (213). With respect to the first axial direction (X-axis direction), the outlet space (214b) can be located between the partition wall (214) and the packing member (23'). The partition wall (214) is positioned between the inlet space (214a) and the outlet space (214b), thereby preventing the first gas that flows into the inlet space (214a) through the first gas inlet (212) from passing through the inside of the cartridge (22) and flowing directly into the outlet space (214b). As a result, the fuel cell humidifier (1) according to the present invention can improve humidification efficiency by increasing the flow rate of the first gas that flows into the inside of the cartridge (22). The partition wall (214) can be coupled to the mid-body (210) so as to block the inner compartment surface (210a) of the mid-body (210). The inner compartment surface (210a) can correspond to the inner surface of the mid-body (210) on which the partition wall (214) is located. The inner compartment surface (210a) and the partition wall (214) can be positioned between the first gas inlet (212) and the first gas outlet (213) with respect to the first axial direction (X-axis direction). With respect to the first axial direction (X-axis direction), the inner compartment surface (210a) and the partition wall (214) can be positioned at points separated by the same distance from the first gas inlet (212) and the first gas outlet (213), respectively. The partition wall (214) and the mid-body (210) can also be formed integrally. In this case, the partition wall portion (214) can be formed to protrude from the inner surface of the compartment (210a) into the inner side of the mid-body (210).

[0016] Referring to Figures 2 to 9, the mid-case (21) can include a bypass hole (215). The bypass hole (215) is formed by penetrating the partition wall (214). A portion of the first gas that flows into the inlet space (214a) through the bypass hole (215) can bypass the cartridge (22) and flow into the outlet space (214b). In other words, a portion of the first gas can flow directly from the inlet space (214a) to the outlet space (214b) without passing through the inside of the cartridge (22). As a result, the fuel cell humidifier (1) according to the present invention can achieve the following effects. First, if the bypass hole (215) is absent, all of the first gas flowing into the inlet space (214a) cannot flow into the outlet space (214b) without passing through the inside of the cartridge (22). As a result, if the flow rate of the first gas accumulating inside the mid-case (21) increases, such as when the flow rate of the first gas flowing into the inlet space (214a) increases or the flow rate of the first gas flowing out from the outlet space (214b) decreases, the shell differential pressure will increase. An increase in shell differential pressure can reduce the efficiency of the fuel cell system, such as by increasing power consumption. Furthermore, this decrease in the efficiency of the fuel cell system due to such an increase in shell differential pressure becomes even more serious as the mid-case (21) is miniaturized. Therefore, if the bypass hole (215) is absent, it is difficult to reduce the overall size. Next, if the bypass hole (215) is present, a portion of the first gas flowing into the inlet space (214a) can bypass the cartridge (22) through the bypass hole (215) and flow into the outlet space (214b). That is, a portion of the first gas can flow directly from the inlet space (214a) to the outlet space (214b) without passing through the inside of the cartridge (22) through the bypass hole (215). As a result, the fuel cell humidifier (1) according to the present invention can reduce the shell differential pressure using the bypass hole (215), thereby contributing to improving the efficiency of the fuel cell system. Furthermore, even if the size of the mid-case (21) is reduced, the fuel cell humidifier (1) according to the present invention can prevent an excessive increase in shell differential pressure using the bypass hole (215), thus improving versatility and applicability to various applications such as hydrogen electric vehicles through miniaturization.

[0017] The bypass hole (215) allows a portion of the first gas that has flowed into the inlet space (214a) through the first gas inlet (212) to pass through to the outlet space (214b). The first gas that has flowed into the outlet space (214b) through the bypass hole (215) can flow out to the outside of the mid-case (21) through the first gas outlet (213). Figure 8 shows the bypass hole (215) as being formed in a form having a triangular cross-section, but it is not limited to this, and the bypass hole (215) can be formed in various forms, such as having a polygonal cross-section like a square, or having a circular cross-section, as long as it allows the first gas to pass from the inlet space (214a) to the outlet space (214b). Referring to Figures 2 to 10, the bypass hole (215) can be formed penetrating the partition wall (214) so ​​as to be positioned between the upper surface (210b) and the bottom surface (210c) of the mid-body (210). At least one of the first gas inlet (212) and the first gas outlet (213) can be positioned on the upper surface (210b) of the mid-body (210). The bottom surface (210c) of the mid-body (210) can be positioned opposite the upper surface (210b) of the mid-body (210). The bottom surface (210c) of the mid-body (210) can be positioned on the side in which gravity acts. As shown in Figure 9, the bypass hole (215) can be positioned at a location where the distance from the top surface (210b) of the mid-body (210) is shorter than the distance from the bottom surface (210c) of the mid-body (210). As shown in Figure 10, the bypass hole (215) can be positioned at a location where the distance from the bottom surface (210c) of the mid-body (210) is shorter than the distance from the top surface (210b) of the mid-body (210). In this case, the bypass hole (215) can discharge condensed water present on the bottom surface (210c) side of the mid-body (210) into the outflow space (214b). Condensed water is generated during the process of water exchange between the first gas and the second gas and may accumulate on the bottom surface (210c) side of the mid-body (210) due to gravity. If the flow rate of such condensed water supplied to the fuel cell stack increases, the efficiency of the fuel cell system may decrease due to flooding. Therefore, the fuel cell humidifier (1) according to the present invention is designed to discharge the condensed water into the outlet space (214b) using the bypass hole (215), and then discharge it to the outside of the mid-case (21) through the first gas outlet (213). Accordingly, the fuel cell humidifier (1) according to the present invention can contribute to improving the efficiency of the fuel cell system by discharging the condensed water using the bypass hole (215).

[0018] Referring to Figures 2 to 11, the cross-sectional area of ​​the bypass hole (215) can be determined according to the cross-sectional area of ​​the inner surface of the compartment (210a). In this case, the cross-sectional area can correspond to the area of ​​the cross-section based on an axial direction perpendicular to the direction in which the inflow space (214a) and the outflow space (214b) are separated from each other. The direction in which the inflow space (214a) and the outflow space (214b) are separated from each other may be parallel to the first axial direction (X-axis direction). The cross-sectional area may be the area of ​​the cross-section based on the second axial direction (Y-axis direction). If the cross-sectional area of ​​the inner surface of the compartment (210a) is 1, the cross-sectional area of ​​the bypass hole (215) can be set to 0.005 or more and 0.1 or less. That is, the cross-sectional area of ​​the bypass hole (215) relative to the cross-sectional area of ​​the inner surface of the compartment (210a) may be 0.5% or more and 10% or less. As a result, the fuel cell humidifier (1) according to the present invention can be implemented to have a humidification efficiency and shell differential pressure within a predetermined range, thereby contributing to improving the efficiency of the fuel cell system. It can be confirmed through the experimental results in Figure 11 that when the cross-sectional area of ​​the bypass hole (215) is between 0.5% and 10% of the cross-sectional area of ​​the inner surface (210a) of the compartment, the humidification efficiency and shell differential pressure are realized to be within a predetermined range. Figure 11 shows the experimental results of measuring the humidification efficiency and shell differential pressure when only the cross-sectional area of ​​the bypass hole (215) is changed while the cross-sectional area of ​​the inner surface (210a) of the compartment is fixed. In Figure 11, the cross-sectional area ratio refers to the ratio of the cross-sectional area of ​​the bypass hole (215) to the cross-sectional area of ​​the inner surface (210a) of the compartment.

[0019] As can be seen in Figure 11, in Example 1, the cross-sectional area of ​​the bypass hole (215) is 0.5% of the cross-sectional area of ​​the inner surface (210a) of the compartment, resulting in a humidification efficiency of 25.0 RH% and a shell differential pressure of 20 kPa. In Example 2, the cross-sectional area of ​​the bypass hole (215) is 1.8% of the cross-sectional area of ​​the inner surface (210a) of the compartment, resulting in a humidification efficiency of 24.3 RH% and a shell differential pressure of 18 kPa. In Example 3, the cross-sectional area of ​​the bypass hole (215) is 3.6% of the cross-sectional area of ​​the inner surface (210a) of the compartment, resulting in a humidification efficiency of 24.0 RH% and a shell differential pressure of 14 kPa. In Example 4, the cross-sectional area of ​​the bypass hole (215) is 10.0% of the cross-sectional area of ​​the inner surface of the compartment (210a), resulting in a humidification efficiency of 23.0 RH% and a shell differential pressure of 10 kPa. Thus, in Examples 1 to 4, when the cross-sectional area of ​​the bypass hole (215) is 0.5% to 10% of the cross-sectional area of ​​the inner surface of the compartment (210a), the humidification efficiency is 23 RH% to 24.5 RH% and the shell differential pressure is 10 kPa to 20 kPa. In contrast, Comparative Example 1 lacks the bypass hole (215), and while its humidification efficiency is 25.0 RH%, the shell differential pressure is significantly higher at 30 kPa. Compared to Example 1, in which the cross-sectional area of ​​the bypass hole (215) is 0.5% of the cross-sectional area of ​​the inner surface of the compartment (210a), Comparative Example 1 shows a significant increase in shell differential pressure despite no significant difference in humidification efficiency. Thus, it can be seen that Comparative Example 1 reduces the efficiency of the fuel cell system compared to Example 1. Furthermore, Comparative Example 2 is a case in which the cross-sectional area of ​​the bypass hole (215) is 11.0% of the cross-sectional area of ​​the inner surface of the compartment (210a), resulting in a humidification efficiency of 22.0 RH% and a shell differential pressure of 10 kPa. In comparison with Example 4, in which the cross-sectional area of ​​the bypass hole (215) is 10.0% of the cross-sectional area of ​​the inner surface of the compartment (210a), Comparative Example 2 shows a 1.0 RH% decrease in humidification efficiency despite no difference in shell differential pressure. Thus, it can be seen that Comparative Example 2, compared to Example 4, only sees a decrease in humidification efficiency, thus degrading the performance of the fuel cell system. Thus, the fuel cell humidifier (1) according to the present invention is realized in which the cross-sectional area of ​​the bypass hole (215) is 0.5% to 10% of the cross-sectional area of ​​the inner surface (210a) of the compartment, resulting in a humidification efficiency of 23RH% to 24.5RH% and a shell differential pressure of 10kPa to 20kPa. Therefore, the fuel cell humidifier (1) according to the present invention can not only improve the performance of the fuel cell system by smoothly supplying humidified gas to the fuel cell stack, but can also contribute to improving the efficiency of the fuel cell system by reducing the shell differential pressure.

[0020] If the cross-sectional area of ​​the inner surface of the compartment (210a) is taken as 1, the cross-sectional area of ​​the bypass hole (215) can be 0.005 or more and 0.06 or less. That is, the cross-sectional area of ​​the bypass hole (215) relative to the cross-sectional area of ​​the inner surface of the compartment (210a) may be 0.5% or more and 6% or less. If the cross-sectional area of ​​the inner surface of the compartment (210a) is taken as 1, the cross-sectional area of ​​the bypass hole (215) can be 0.005 or more and 0.04 or less. That is, the cross-sectional area of ​​the bypass hole (215) relative to the cross-sectional area of ​​the inner surface of the compartment (210a) may be 0.5% or more and 4% or less. Multiple bypass holes (215) can be formed in the partition wall (214). The bypass holes (215, 215') can be formed penetrating the partition wall (214) at positions spaced apart from each other. This allows the fuel cell humidifier (1) according to the present invention to be implemented in such a way that the first gas can be bypassed at different positions in the partition wall (214). In this case, if the cross-sectional area of ​​the inner surface of the compartment (210a) is 1, the sum of the cross-sectional areas of the bypass holes (215, 215') can be 0.005 or more and 0.1 or less. That is, the sum of the cross-sectional areas of the bypass holes (215, 215') relative to the cross-sectional area of ​​the inner surface of the compartment (210a) may be 0.5% or more and 10% or less. Figure 10 shows all of the bypass holes (215, 215') positioned such that the distance from the bottom surface (210c) of the mid-body (210) is shorter than the distance from the top surface (210b) of the mid-body (210). However, the diagram is not limited to this, and all of the bypass holes (215, 215') can also be positioned such that the distance from the top surface (210b) of the mid-body (210) is shorter than the distance from the bottom surface (210c) of the mid-body (210). Some of the bypass holes (215, 215') can be positioned closer to the bottom surface (210c) of the mid-body (210), and some of the bypass holes (215, 215') can be positioned closer to the top surface (210b) of the mid-body (210). Furthermore, although Figure 10 shows that two bypass holes (215, 215') are formed in the partition wall (214), the design is not limited to this, and three or more bypass holes (215) can also be formed in the partition wall (214). Referring to Figures 2 to 10, the mid-case (21) can include an insertion hole (216).

[0021] The insertion hole (216) is formed by penetrating the partition wall (214). The cartridge (22) can be inserted into the insertion hole (216). The partition wall (214) supports the cartridge (22) inserted into the insertion hole (216), thereby connecting the cartridge (22) to the mid-body (210). The cartridge (22) can be inserted into the insertion hole (216) by interference fit. The insertion hole (216) and the bypass hole (215) can be formed by penetrating the partition wall (214) at positions separated from each other. The mid-case (21) may also include a plurality of insertion holes (216). The insertion holes (216, 216', 216") may be formed penetrating the partition wall (214) at positions spaced apart from each other. This allows the fuel cell humidifier (1) according to the present invention to be embodied in the mid-case (21) to house a plurality of cartridges (22). Figure 8 shows the partition wall (214) with two insertion holes (216, 216') formed therein, and Figure 10 shows the partition wall (214) with three insertion holes (216, 216', 216") formed therein, but is not limited to these, and the partition wall (214) may also have four or more insertion holes (216). The present invention described above is not limited to the embodiments and accompanying drawings, and it will be apparent to those with ordinary skill in the art to which the present invention pertains that various substitutions, modifications, and alterations are possible without departing from the technical spirit of the present invention.

Claims

1. A mid-case provided in a fuel cell humidifier, which includes a humidification module for humidifying dry gas supplied to a fuel cell stack using a humidified gas, a first cap coupled to one end of the humidification module, and a second cap coupled to the other end of the humidification module. A mid-body housing at least one cartridge containing multiple hollow fiber membranes; A partition wall disposed inside the mid-body, which divides the inside of the mid-body into an inlet space into which the first gas flows and an outlet space into which the first gas flows out; and A bypass hole formed through the partition wall portion allows a portion of the first gas flowing into the inflow space to bypass the cartridge and flow into the outflow space; The partition wall is connected to the mid-body so as to block the inner surface of the mid-body, A mid-case for a fuel cell humidifier, characterized in that, if the cross-sectional area of ​​the inner surface of the compartment is 1, the cross-sectional area of ​​the bypass hole is 0.005 or more and 0.1 or less.

2. The mid-case includes an insertion hole formed through the partition wall, The cartridge is inserted into the aforementioned insertion hole. The mid-case of a fuel cell humidifier according to claim 1, characterized in that the bypass hole and the insertion hole are formed penetrating the partition wall at positions separated from each other.

3. Multiple bypass holes are formed in the partition wall portion. The mid-case of a fuel cell humidifier according to claim 1, characterized in that the bypass holes are formed penetrating the partition wall at positions spaced apart from each other.

4. The partition wall is connected to the mid-body so as to block the inner surface of the mid-body, The mid-case for a fuel cell humidifier according to claim 3, characterized in that, if the cross-sectional area of ​​the inner surface of the compartment is 1, the sum of the cross-sectional areas of each of the bypass holes is 0.005 or more and 0.1 or less.

5. The mid-case includes a first gas inlet for introducing a first gas into the inlet space, and a first gas outlet for discharging the first gas from the outlet space. The mid-case of a fuel cell humidifier according to claim 1, characterized in that the bypass hole allows a portion of the first gas that has flowed into the inflow space to pass through the first gas inlet to the outflow space.

6. The mid-case for a fuel cell humidifier according to claim 1, characterized in that the bypass hole is positioned at a location where the distance from the bottom surface of the mid-case is shorter than the distance from the top surface of the mid-case, thereby discharging condensed water present on the bottom side of the mid-case into the outflow space.

7. A humidification module that uses a humidified gas to humidify the dry gas supplied to the fuel cell stack; A first cap coupled to one end of the humidifying module; and A second cap coupled to the other end of the humidification module; The humidification module includes a mid-case with both ends open, and at least one cartridge containing a plurality of hollow fiber membranes. The aforementioned mid-case is, The main unit in which the aforementioned cartridge is housed; A partition wall disposed inside the mid-body, which divides the inside of the mid-body into an inlet space into which the first gas flows and an outlet space into which the first gas flows out; and A bypass hole formed through the partition wall portion allows a portion of the first gas flowing into the inflow space to bypass the cartridge and flow into the outflow space; The partition wall is connected to the mid-body so as to block the inner surface of the mid-body, A fuel cell humidifier characterized in that, if the cross-sectional area of ​​the inner surface of the compartment is 1, the cross-sectional area of ​​the bypass hole is 0.005 or more and 0.1 or less.

8. The mid-case includes an insertion hole formed through the partition wall, The cartridge is inserted into the aforementioned insertion hole. The fuel cell humidifier according to claim 7, characterized in that the bypass hole and the insertion hole are formed penetrating the partition wall at positions separated from each other.

9. Multiple bypass holes are formed in the partition wall portion. The fuel cell humidifier according to claim 7, characterized in that the bypass holes are formed penetrating the partition wall at positions spaced apart from each other.

10. The partition wall is connected to the mid-body so as to block the inner surface of the mid-body, The fuel cell humidifier according to claim 9, characterized in that, if the cross-sectional area of ​​the inner surface of the compartment is 1, the sum of the cross-sectional areas of each of the bypass holes is 0.005 or more and 0.1 or less.

11. The mid-case includes a first gas inlet for introducing a first gas into the inlet space, and a first gas outlet for discharging the first gas from the outlet space. The humidifier for a fuel cell according to claim 7, characterized in that the bypass hole allows a portion of the first gas that has flowed into the inlet space to pass through the first gas inlet to the outlet space side.

12. The fuel cell humidifier according to claim 7, characterized in that the bypass hole is positioned at a location where the distance from the bottom surface of the mid-body is shorter than the distance from the top surface of the mid-body, and condensed water present on the bottom side of the mid-body is discharged into the outflow space.

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