Mid-case of fuel cell humidifier and fuel cell humidifier

Abstract

A mid-body that houses at least one cartridge containing a plurality of hollow fiber membranes; and a bypass portion that bypasses a first gas flowing in through a first gas inlet of a first cap and allows the first gas to flow into a cartridge side housed inside the mid-body, the bypass portion including a mid-case of a fuel cell humidifier and a fuel cell humidifier that protrude from the mid-body at a position overlapping the cartridge housed inside the mid-body.

Description

Technical Field

[0001] The present invention relates to a fuel cell humidifier for supplying 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 since there is no heat loss, it has the advantage of being about twice as efficient as an internal combustion engine. 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, a fuel cell has the advantage of being not only environmentally friendly but also capable of reducing concerns about resource depletion associated with the increase in energy consumption. 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), and alkaline fuel cells (AFCs) 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 for small-scale stationary power generation devices but also as a transportation system because it operates at a lower temperature compared to other fuel cells and has a high output density, enabling miniaturization. One of the most important factors in improving the performance of polymer electrolyte fuel cells (PEMFCs) is to maintain the water content by supplying a certain amount of water or more to the polymer electrolyte membrane (Polymer Electrolyte Membrane or Proton Exchange Membrane: PEM) of the membrane-electrode assembly (MEA). This is because when the polymer electrolyte membrane dries, the power generation efficiency drops sharply. As methods for humidifying the polymer electrolyte membrane, there are: 1) the bubbler humidification method in which water is filled in a pressure-resistant container 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, etc. Among these, the membrane humidification method of humidifying the polymer electrolyte membrane by using a membrane that selectively permeates only the water vapor contained in the exhaust gas and providing the water vapor to the air supplied to the polymer electrolyte membrane is advantageous in that the 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 humidifier using a hollow fiber membrane, high integration of the hollow fiber membrane with a large contact surface area is possible. Therefore, 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 from the fuel cell at a high temperature can be recovered and reused through the humidifier. Figure 1 is a schematic exploded perspective view of a normal humidifier for a fuel cell. As illustrated in Figure 1, a normal humidifier (100) of the membrane humidification method includes a humidification module (110) in which moisture exchange is performed between the air supplied from the outside and the 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.

[0003] 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) inside the mid-case (111). Both ends of the hollow fiber membrane (112) are potted in a fixing layer (113). The fixing layer (113) is generally formed by curing a liquid polymer such as a liquid polyurethane resin by a casting method. The fixing layer (113) in which the ends of the hollow fiber membrane (112) are potted and the resin layer (114) between the fixing layer (113) and the mid-case (111) block the internal space of the cap (120) from the internal space of the mid-case (111). Similar to the fixing layer (113), the resin layer (114) is generally formed by curing a liquid polymer such as a liquid polyurethane resin by a casting method. Air supplied from the outside flows along the hollow of the hollow fiber membrane (112). The exhaust gas flowing into the mid-case (111) through the exhaust gas wet gas inlet (111a) contacts the outer surface of the hollow fiber membrane (112) and then flows out of the mid-case (111) through the exhaust gas wet gas outlet (111b). When the exhaust gas contacts the outer surface of the hollow fiber membrane (112), the moisture contained in the exhaust gas permeates the hollow fiber membrane (112), thereby humidifying the air flowing along the hollow of the hollow fiber membrane (112). In this case, conventionally, the exhaust gas flowing into the mid-case (111) flowed toward the hollow fiber membrane (112). As a result, conventionally, there has been a problem that the hollow fiber membrane (112) is damaged or broken because the pressure of the exhaust gas flowing into the mid-case (111) is directly applied to the hollow fiber membrane (112).

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present invention has been devised to solve the above-described problems, and provides a mid-case for a fuel cell humidifier and a fuel cell humidifier capable of reducing damage or breakage occurring in a hollow fiber membrane.

Means for Solving the Problems

[0005] In order to solve the above problems, the present invention can include the following configuration. The mid-case of the fuel cell humidifier according to the present invention is provided in a fuel cell humidifier including a humidifying module that humidifies dry gas supplied to a fuel cell stack using wet 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 includes a mid-body that houses at least one cartridge including a plurality of hollow fiber membranes; and a bypass portion that bypasses the first gas flowing in through the first gas inlet of the first cap and flows into the cartridge side housed inside the mid-body. The bypass portion can protrude from the mid-body at a position overlapping the cartridge housed inside the mid-body. The humidifier for a fuel cell according to the present invention can include a humidification module that humidifies dry gas supplied to a fuel cell stack using humid 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 can include a mid-case with both ends open and at least one cartridge including a plurality of hollow fiber membranes. The first cap can include a first gas inlet through which a first gas for supply to the inside of the mid-case flows in, and a first port that communicates with the hollow fiber membrane and through which a second gas flows in or out. The mid-case can include a mid-body in which the cartridge is housed, and a bypass portion that bypasses the first gas flowing in through the first gas inlet and causes it to flow into the side of the cartridge housed inside the mid-body. The bypass portion can protrude from the mid-body at a position overlapping the cartridge housed inside the mid-body.

Effects of the Invention

[0006] The present invention can reduce the risk of damage or breakage of the hollow fiber membrane due to gas pressure. Therefore, the present invention can extend the service life and reduce maintenance costs.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0008] Hereinafter, embodiments of the humidifier for a fuel cell according to the present invention will be described in detail with reference to the accompanying drawings. Since the mid-case of the humidifier for a fuel cell according to the present invention can be included in the humidifier for a fuel cell according to the present invention, it will be described together while explaining the embodiments of the humidifier for a fuel cell according to the present invention. On the other hand, in FIG. 7, the two parallel curves are omitted lines. Further, in FIGS. 7 and 9, the hollow fiber membrane is simply shown by hatching, and the inner case is omitted. Referring to FIGS. 2 to 4, the humidifier (1) for a fuel cell according to the present invention humidifies the dry gas supplied to the fuel cell stack (not shown) using the wet gas. The wet gas can be the one discharged from the fuel cell stack. The dry gas can be a fuel gas or air. The dry gas can be supplied to the fuel cell stack after being humidified by the wet gas. The humidifier (1) for a fuel cell 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 FIGS. 2 to 4, the humidification module (2) humidifies dry gas. One end of the humidification module (2) can be connected to the first cap (3). The other end of the humidification module (2) can be connected to the second cap (4). The humidification module (2) can supply the fuel cell stack with dry gas humidified using the first gas and the second gas. When the first gas is dry gas, the second gas can be wet gas. In this case, after the first gas is humidified by the second gas, it can be supplied to the fuel cell stack. When the first gas is wet gas, the second gas can be dry gas. In this case, after the second gas is humidified by the first gas, it can be supplied to the fuel cell stack. The humidification module (2) includes a mid-case (21) and at least one cartridge (22). The mid-case (21) is for connecting the cartridge (22). The cartridge (22) can be arranged inside the mid-case (21). Both ends of the mid-case (21) are open. In this case, an accommodation hole (211) can be formed in the mid-case (21). The accommodation 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 arranged in the accommodation hole (211). The mid-case (21) can include a mid-body (210). The mid-body (210) is for housing the cartridge (22). The cartridge (22) can be housed in the mid-body (210) by being arranged inside the mid-body (210). The mid-body (210) can house at least one cartridge (22). The accommodation hole (211) can be formed to penetrate the mid-body (210) in the first axial direction (X-axis direction).

[0009] The mid-case (21) can form a first gas inlet (30) and a first gas outlet (212). The first gas inlet (30) can allow the first gas to flow into the interior of the mid-case (21). The first gas outlet (212) can allow the first gas to flow out from the interior of the mid-case (21). In this case, the first gas outlet (212) can allow the first gas flowing out from the cartridge (22) to flow out to the outside of 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) for modularization. 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). 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) for modularization. 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) can 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 a liquid polyurethane resin through a casting process. A part of the first fixing layer (223) can be located inside the inner case (222), and the remaining part can protrude outside the inner case (222). The first fixing layer (223) can also fix one end of the hollow fiber membrane (221) and the inner case (222).

[0010] The cartridge (22) can 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 a liquid polyurethane resin through a casting process. A part of the second fixing layer (224) can be located inside the inner case (222), and the remaining part can protrude outside the inner case (222). The second fixing layer (224) can also fix the other end of the hollow fiber membrane (221) and the inner case (222). Since the second fixing layer (224) and the first fixing layer (223) are formed so as not to 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 fixing layer (224) and the first fixing layer (223), and can flow out from the hollow of the hollow fiber membrane (221) without being obstructed by the second fixing layer (224) and the first fixing layer (223). Referring to FIGS. 2 to 6, the cartridge (22) can include a second gas inlet (225) and a second gas outlet (226). 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 as a single through hole penetrating the inner case (222). As shown in FIG. 6, the second gas inlet (225) can also be embodied as 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 portions 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 pattern. The second axial direction (Y-axis direction) is an axial direction perpendicular to the first axial direction (X-axis direction).

[0011] 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 the inside of the inner case (222). The second gas outlet (226) can be formed to penetrate the inner case (222). As shown in FIG. 5, the second gas outlet (226) can be embodied as a single through-hole penetrating the inner case (222). As shown in FIG. 6, the second gas outlet (226) can also be embodied as a plurality of through-holes penetrating the inner case (222). In this case, the second gas outlet (226) can include a plurality of outflow windows (226a) formed to penetrate different portions of the inner case (222). The outflow windows (226a) 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 pattern. The second gas outlet (226) and the second gas inlet (225) can be arranged at positions spaced apart from each other along the first axial direction (X-axis direction). When the first gas is a wet gas, the first gas is supplied through the first gas inlet (30) between the inner surface of the mid-case (21) and the outer surface of the cartridge (22), and through the second gas inlet (225) into the interior of the cartridge (22), and can contact the outer surface of the hollow fiber membrane (221). In this process, the moisture contained in the first gas permeates through the hollow fiber membrane (221), thereby humidifying the second gas 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 flows out between the outer surface of the cartridge (22) and the inner surface of the mid-case (21) through the second gas outlet (226), and can flow out of the mid-case (21) through the first gas outlet (212). In this case, the first gas can be off-gas discharged from the fuel cell stack. When the first gas is a dry gas, the first gas is supplied through the first gas inlet (30) between the inner surface of the mid-case (21) and the outer surface of the cartridge (22), and through the second gas inlet (225) into the interior of the cartridge (22), where it can contact the outer surface of the hollow fiber membrane (221). In this process, the moisture in 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 then through the first gas outlet (212) to the outside of the mid-case (21), 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 can be off-gas discharged from the fuel cell stack. The humidifying module (2) can include a plurality of packing members (23, 23').

[0012] The packing members (23, 23') seal the space between the cartridge (22) and the mid-case (21) so as to prevent the direct mixing of the first gas and the second gas. 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 respectively disposed on both sides of the cartridge (22). Although not shown, resin layers can also be formed on both sides of the cartridge (22) instead of the packing members (23, 23'). The resin layer can be formed by curing a liquid polymer such as liquid polyurethane resin by a casting method. Referring to FIGS. 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 with respect to the space between the cartridge (22) and the mid-case (21) by the packing member (23) or the resin layer. The first cap (3) can 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). Thereby, 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 FIGS. 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 spaced apart 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 with respect to the space between the cartridge (22) and the mid-case (21) by the packing member (23') or the resin layer. The second cap (4) can include a second port (41). The second port (41) is for the second gas to flow. The second port (41) can communicate with the hollow fiber membrane (221). Thereby, 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 while sequentially passing through the second cap (4), the hollow of 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 while sequentially passing through the first cap (3), the hollow of the hollow fiber membrane (221), and the second cap (4). Here, as shown in FIG. 7, when the first gas flowing into the interior of the mid-case (21) through the first gas inlet (30) immediately flows toward the cartridge (22), there is a risk that the hollow fiber membrane (221) may be damaged or broken due to the pressure of the first gas. To prevent this, the humidifier (1) for a fuel cell according to the present invention can be configured such that the first gas flowing in through the first gas inlet (30) bypasses and flows into the cartridge (22) side. Therefore, in the humidifier (1) for a fuel cell according to the present invention, the mid-case (21) and the first cap (3) can be configured as follows. Referring to FIGS. 2 to 10, the mid-case (21) can include a bypass portion (213).

[0013] The bypass portion (213) bypasses the first gas flowing in through the first gas inlet (30) and allows it to flow into the cartridge (22) side housed inside the mid-body (210). The bypass portion (213) can be connected so as to communicate with the inside of the first cap (3) and the inside of the mid-body (210), respectively. In this case, the first cap (3) can include the first gas inlet (30). Thereby, the bypass portion (213) can communicate with the first gas inlet (30) through the inside of the first cap (3). Therefore, the first gas flowing in through the first gas inlet (30) can flow into the cartridge (22) side housed inside the mid-body (210) after bypassing along the bypass portion (213). In this way, by using the bypass portion (213) to bypass the first gas, the humidifier (1) for a fuel cell according to the present invention can reduce the pressure of the first gas flowing into the cartridge (22) side. Thereby, the humidifier (1) for a fuel cell according to the present invention can reduce the risk that the hollow fiber membrane (221) is damaged or broken due to the pressure of the first gas flowing into the mid-body (210). Therefore, the humidifier (1) for a fuel cell according to the present invention can reduce maintenance costs, operating costs, etc. by extending the service life of the hollow fiber membrane (221). Further, the humidifier (1) for a fuel cell according to the present invention can contribute to increasing the operating rate of the fuel cell stack by extending the maintenance cycle for the hollow fiber membrane (221). The bypass portion (213) can protrude from the mid-body (210). Thereby, the humidifier (1) for a fuel cell according to the present invention can embody a flow path for bypassing the first gas to the outside of the mid-body (210) by using the bypass portion (213). Therefore, the humidifier (1) for a fuel cell according to the present invention can be embodied such that the flow path for bypassing the first gas using the bypass portion (213) and the flow path of the first gas flowing between the inside of the mid-body (210) and the outside of the cartridge (22) do not interfere with each other. Thereby, the humidifier (1) for a fuel cell according to the present invention is embodied such that the flow path of the first gas flowing between the inside of the mid-body (210) and the outside of the cartridge (22) does not become narrow due to the flow path for bypassing the first gas. Therefore, the humidifier (1) for a fuel cell according to the present invention can reduce the pressure of the first gas applied to the hollow fiber membrane (221) and at the same time can be embodied such that moisture exchange between the first gas and the second gas is smoothly performed. The bypass portion (213) can be arranged to overlap the cartridge (22) housed inside the mid-body (210). One end of the bypass portion (213) can be connected to communicate with the inside of the first cap (3) arranged on one end side of the mid-body (210). The other end of the bypass portion (213) can be connected to communicate with the inside of the mid-body (210). In this case, the other end of the bypass portion (213) can be arranged to overlap the cartridge (22) housed inside the mid-body (210). Thereby, since one end of the bypass portion (213) and the other end of the bypass portion (213) are arranged to be separated from each other, the humidifier (1) for a fuel cell according to the present invention can be embodied such that the first gas gradually decreases in pressure while flowing from one end of the bypass portion (213) to the other end side of the bypass portion (213). In this case, as the flow rate of the first gas gradually decreases, the pressure applied to the hollow fiber membrane (221) by the first gas can be reduced. Therefore, the humidifier (1) for a fuel cell according to the present invention can be embodied such that the first gas flows smoothly to the cartridge (22) side through the bypass portion (213) by preventing the pressure of the first gas from changing abruptly. One end of the bypass portion (213) and the other end of the bypass portion (213) can be arranged at positions separated from each other with reference to the first axial direction (X-axis direction).

[0014] The bypass portion (213) can include a first bypass passage (213a) and a second bypass passage (213b). The first bypass passage (213a) communicates with the inside of the first cap (3). The first bypass passage (213a) can function as an inlet through which the first gas flows into the bypass portion (213). The first bypass passage (213a) can be formed to penetrate one end of the bypass portion (213). The second bypass passage (213b) communicates with the inside of the mid-body (210). The second bypass passage (213b) can function as an outlet for the first gas to flow out from the bypass portion (213). The second bypass passage (213b) can be formed by penetrating the other end of the bypass portion (213). The second bypass passage (213b) and the first bypass passage (213a) can be formed by penetrating the bypass portion (213) at different positions and in different directions. For example, with reference to FIG. 9, the second bypass passage (213b) can be formed by penetrating the bypass portion (213) in a downward direction facing the mid-body (210) side from the other end of the bypass portion (213). In this case, the first bypass passage (213a) can be formed by penetrating the bypass portion (213) in a leftward direction facing the first cap (3) from one end of the bypass portion (213). Thereby, the first gas flows in through the first bypass passage (213a), flows along the first axial direction (X-axis direction), and then flows out in the downward direction through the second bypass passage (213b), so that it can flow inside the mid-body (210). Therefore, the humidifier (1) for a fuel cell according to the present invention can further reduce the pressure of the first gas applied to the hollow fiber membrane (221) by embodying the flow direction to be changed in the process of flowing from the bypass portion (213) into the inside of the mid-body (210). On the other hand, the second bypass passage (213b) can also be formed by penetrating the other end of the bypass portion (213) and the entire mid-body (210). Thereby, the inside of the bypass portion (213) and the inside of the mid-body (210) can be connected to communicate with each other through the second bypass passage (213b). The bypass portion (213) and the mid-body (210) can also be integrally formed. The mid-case (21) can include a first mid-passage (210a). The first middle passage (210a) communicates with the inside of the first cap (3). The first middle passage (210a) can function as a passage for the second gas to flow in or out between the inside of the first cap (3) and the hollow fiber membrane (221). The first middle passage (210a) can be formed by penetrating one end of the middle body (210). The first middle passage (210a) can correspond to one end of the accommodation hole (211). One end of the hollow fiber membrane (221) fixed by the first fixing layer (223) can be disposed in the first middle passage (210a).

[0015] The middle-case (21) can include a second middle passage (not shown). The second middle passage can function as a passage for the second gas to flow in or out between the inside of the second cap (4) and the hollow fiber membrane (221). The second middle passage can be formed by penetrating the other end of the middle body (210). The second middle passage can correspond to the other end of the accommodation hole (211). The other end of the hollow fiber membrane (221) fixed by the second fixing layer (224) can be disposed in the second middle passage. Here, the first mid-channel (210a) and the first bypass channel (213a) can be embodied to have the following cross-sectional areas, respectively. In this case, the cross-sectional area is related to the area through which each of the first mid-channel (210a) and the first bypass channel (213a) can allow a fluid to pass. The cross-sectional area of each of the first mid-channel (210a) and the first bypass channel (213a) is the area of a cross-section with respect to the vertical direction (Z-axis direction). The vertical direction (Z-axis direction) can be an axial direction perpendicular to each of the first axial direction (X-axis direction) and the second axial direction (Y-axis direction). The vertical direction (Z-axis direction) can also be an axial direction parallel to the second axial direction (Y-axis direction). In this case, the cartridge (22) can be arranged such that the second gas inlet (225) and the second gas outlet (226) face other directions except the direction facing the second bypass channel (213b). The first mid-channel (210a) and the first bypass channel (213a) can be arranged to be spaced apart from each other along the vertical direction (Z-axis direction). First, the cross-sectional area of the first mid-passage (210a) can be made larger than the cross-sectional area of the first bypass passage (213a). In Comparative Example 1 where the cross-sectional area of the first bypass passage (213a) is larger than or the same as the cross-sectional area of the first mid-passage (210a), when the first gas flows into the inside of the bypass portion (213) through the first bypass passage (213a), the flow velocity becomes too slow. As a result, in Comparative Example 1, the first gas cannot be transmitted to the hollow fiber membrane (221) disposed relatively inside among the hollow fiber membranes (221) inside the cartridge (22), so there is a possibility that the humidification efficiency may decrease. To prevent this, the humidifier (1) for a fuel cell according to the present invention can make the cross-sectional area of the first bypass passage (213a) smaller than the cross-sectional area of the first mid-passage (210a). Thereby, the humidifier (1) for a fuel cell according to the present invention can increase the flow velocity of the first gas flowing into the inside of the bypass portion (213) through the first bypass passage (213a) compared with Comparative Example 1. Therefore, the ratio of the hollow fiber membranes (221) involved in humidification can be further increased among the hollow fiber membranes (221) inside the cartridge (22). Accordingly, the humidifier (1) for a fuel cell according to the present invention can have a more improved humidification efficiency compared with Comparative Example 1. Next, assuming that the cross-sectional area of the first mid-passage (210a) is 1, the cross-sectional area of the first bypass passage (213a) can be embodied to be 0.1 or more and 0.45 or less. That is, the cross-sectional area of the first bypass passage (213a) relative to the cross-sectional area of the first mid-passage (210a) may be 10% or more and 45% or less. Thereby, the humidifier (1) for a fuel cell according to the present invention can be embodied to have a humidification efficiency and a shell differential pressure within a predetermined range. The shell differential pressure is related to the pressure acting inside the mid-case (21) and inside the cartridge (22) in the process where the first gas flows in through the first gas inlet (30) and flows out through the first gas outlet (212). If the shell differential pressure is too high, there is a risk that the mid-case (21), the cartridge (22), and the hollow fiber membrane (221) may be damaged or broken. If the shell differential pressure is too low, the residence time of the first gas inside the mid-case (21) and inside the cartridge (22) becomes too short, and the humidification efficiency may decrease.

[0016] Referring to FIGS. 2 to 11, when the cross-sectional area of the first bypass passage (213a) is 10% or more and 45% or less with respect to the cross-sectional area of the first mid-passage (210a), it can be confirmed through the experimental results of FIG. 11 that the humidifier is embodied to have a humidification efficiency and a shell differential pressure within a predetermined range. FIG. 11 is an experimental result of measuring the humidification efficiency and the shell differential pressure by changing only the cross-sectional area of the first bypass passage (213a) while fixing the cross-sectional area of the first mid-passage (210a) and the cross-sectional area of the second bypass passage (213b). All the experimental results in FIG. 11 are those obtained by measuring the humidification efficiency and the shell differential pressure when the same flow rate of the first gas is supplied through the first gas inlet (30) with the cross-sectional area of the second bypass passage (213a) embodied to be 60% with respect to the cross-sectional area of the first mid-passage (210a). Also, in FIG. 11, the cross-sectional area ratio means the cross-sectional area ratio of the first bypass passage (213a) with respect to the cross-sectional area of the first mid-passage (210a). As can be seen through FIG. 11, in Example 1, the cross-sectional area of the first bypass passage (213a) with respect to the cross-sectional area of the first mid-passage (210a) was embodied as 10%, the humidification efficiency was 32 RH%, and the shell differential pressure was 21 kPa. In Example 2, the cross-sectional area of the first bypass passage (213a) with respect to the cross-sectional area of the first mid-passage (210a) was embodied as 30%, the humidification efficiency was 30 RH%, and the shell differential pressure was 19 kPa. In Example 3, the cross-sectional area of the first bypass passage (213a) with respect to the cross-sectional area of the first mid-passage (210a) was embodied as 10%, the humidification efficiency was 32 RH%, and the shell differential pressure was 21 kPa. Thus, it can be seen that in Examples 1 to 3, when the cross-sectional area of the first bypass passage (213a) with respect to the cross-sectional area of the first mid-passage (210a) is embodied as 10% or more and 45% or less, the humidification efficiency is 30 to 32 RH%, and the shell differential pressure is 18 to 21 kPa. Compared with such Examples 1 to 3, in Comparative Example 2, the cross-sectional area of the first bypass passage (213a) with respect to the cross-sectional area of the first mid-passage (210a) was embodied as 8%, the humidification efficiency was 31.5 RH%, but the shell differential pressure was significantly high at 32 kPa. Through such Comparative Example 2, it can be seen that when the cross-sectional area of the first bypass passage (213a) with respect to the cross-sectional area of the first mid-passage (210a) is embodied as less than 10%, the shell differential pressure becomes significantly high, and the risk of damage to the mid-case (21), the cartridge (22), and the hollow fiber membrane (221) increases. Also, compared with Examples 1 to 3, in Comparative Example 3, the cross-sectional area of the first bypass passage (213a) with respect to the cross-sectional area of the first mid-passage (210a) was embodied as 47%, the shell differential pressure was 17.5 kPa, but the humidification efficiency was significantly low at 22 RH%. Through such Comparative Example 3, it can be seen that when the cross-sectional area of the first bypass passage (213a) with respect to the cross-sectional area of the first mid-passage (210a) is embodied as more than 45%, the humidification efficiency becomes significantly low.

[0017] Thus, it can be seen that the fuel cell humidifier (1) according to the present invention is embodied such that the cross-sectional area of the first bypass passage (213a) with respect to the cross-sectional area of the first mid passage (210a) is 10% or more and 45% or less, so as to have a humidification efficiency of 30 to 32 RH% and a shell differential pressure of 18 to 21 kPa. Therefore, the fuel cell humidifier (1) according to the present invention can reduce the risk of damage or breakage of the mid-case, the cartridge (22), and the hollow fiber membrane (221), and at the same time, contribute to further improving the performance of the fuel cell system through the improvement of the humidification efficiency. On the other hand, the cross-sectional area of the second bypass passage (213b) can be made larger than the cross-sectional area of the first bypass passage (213a). In this case, the cross-sectional area of the second bypass passage (213b) is the area of the cross-section with respect to the first axial direction (X-axis direction). In the case of Comparative Example 4 where the cross-sectional area of the second bypass passage (213b) is smaller than or the same as the cross-sectional area of the first bypass passage (213a), the flow rate of the first gas becomes too fast in the process of flowing into the inside of the mid-body (210) through the second bypass passage (213b). As a result, in Comparative Example 4, the pressure of the first gas applied to the hollow fiber membrane (221) excessively increases, and the risk of damage or breakage of the hollow fiber membrane (221) may increase. To prevent this, the fuel cell humidifier (1) according to the present invention can be embodied such that the cross-sectional area of the second bypass passage (213b) is larger than the cross-sectional area of the first bypass passage (213a). Thereby, the fuel cell humidifier (1) according to the present invention can reduce the flow rate of the first gas flowing into the inside of the mid-body (210) through the second bypass passage (213b) compared to Comparative Example 4, so that the risk of damage or breakage of the hollow fiber membrane (221) due to the pressure of the first gas can be reduced. On one hand, when the cross-sectional area of the first mid-channel (210a) is set to 1, the cross-sectional area of the second bypass channel (213b) can be embodied to be 0.2 or more and 0.8 or less. That is, the cross-sectional area of the second bypass channel (213b) relative to the cross-sectional area of the first mid-channel (210a) may be 20% or more and 80% or less. Thereby, the humidifier (1) for a fuel cell according to the present invention can be embodied to have a humidification efficiency and a shell differential pressure within a predetermined range. In the case of Comparative Example 5 in which the cross-sectional area of the second bypass channel (213b) relative to the cross-sectional area of the first mid-channel (210a) is less than 20%, the flow rate of the first gas flowing into the inside of the mid-body (210) through the second bypass channel (213b) becomes too fast, so there is a high possibility that the hollow fiber membrane (221) may be damaged or broken. In the case of Comparative Example 6 in which the cross-sectional area of the second bypass channel (213b) relative to the cross-sectional area of the first mid-channel (210a) exceeds 80%, the flow rate of the first gas flowing into the inside of the mid-body (210) through the second bypass channel (213b) becomes too slow, so the first gas cannot be transmitted to the hollow fiber membrane (221) disposed relatively inside among the hollow fiber membranes (221), and thus the humidification efficiency may decrease. Considering this, by embodying the cross-sectional area of the second bypass channel (213b) relative to the cross-sectional area of the first mid-channel (210a) to be 20% or more and 80% or less, the humidifier (1) for a fuel cell according to the present invention can reduce the risk of damage or breakage of the hollow fiber membrane (221), and at the same time, contribute to further improving the performance of the fuel cell system through the improvement of the humidification efficiency. Even when the cross-sectional area of the second bypass channel (213b) relative to the cross-sectional area of the first mid-channel (210a) is 20% or more and 80% or less, the cross-sectional area of the second bypass channel (213b) can be embodied to be larger than the cross-sectional area of the first bypass channel (213a).

[0018] Referring to FIGS. 2 to 10, the first cap (3) may include the first gas inlet (30), the first communication flow path (32), the second communication flow path (33), and the partition portion (34). The first gas inlet (30) is for the first gas to flow into the inside of the mid-case (21). The first gas inlet (30) can be coupled to the first cap (3) so as to communicate with the inside of the first cap (3). Compared with the comparative example in which the first gas inlet (30) is disposed in the mid-case (21), the embodiment in which the first gas inlet (30) is disposed in the first cap (3) can reduce the separated distance between the first gas inlet (30) and the supply source (not shown) of the first gas. Accordingly, the embodiment in which the first gas inlet (30) is disposed in the first cap (3) can shorten the length of the hose for connecting the first gas inlet (30) and the supply source, contributing to the overall miniaturization of the fuel cell system. Also, the embodiment in which the first gas inlet (30) is disposed in the first cap (3) can implement the hose for connecting the first gas inlet (30) and the supply source in a straight line, contributing to further miniaturization of the fuel cell system. The supply source may be the fuel cell stack. In this case, the first gas may be the exhaust gas discharged from the fuel cell stack. The first gas inlet (30) can protrude from the first cap (3). The first gas inlet (30) and the first port (31) can protrude in the same direction as each other. With reference to FIG. 10, the first gas inlet (30) and the first port (31) can protrude in the upward direction from the upper surface of the first cap (3). When the first gas is the exhaust gas discharged from the fuel cell stack and the second gas is the humidified gas supplied to the fuel cell stack, all of the first gas inlet (30) and the first port (31) can be connected to the fuel cell stack. In this case, the first port (31) can supply the second gas humidified by the first gas to the fuel cell stack. Therefore, the humidifier (1) for a fuel cell according to the present invention can improve the ease of work of connecting the first gas inlet (30) and the first port (31) to the fuel cell stack. Further, the humidifier (1) for a fuel cell according to the present invention can contribute to making the fuel cell system more compact by shortening the length of the hose for connecting the first gas inlet (30) and the first port (31) to the fuel cell stack. On the other hand, the first gas outlet (212) can protrude from the mid body (210). The first gas outlet (212) and the first gas inlet (30) can protrude in the same direction as each other. The first gas outlet (212) and the first gas inlet (30) can also protrude in different directions from each other.

[0019] The first communication flow path (32) communicates the first gas inlet (30) with the bypass portion (213). The first communication flow path (32) can be disposed inside the first cap (3). The first communication flow path (32) can be formed by penetrating one end of the first cap (3). One end of the first cap (3) is a portion facing one end of the mid-case (21). When the first cap (3) is coupled to the mid-case (21), the first communication flow path (32) can be connected to communicate with the first bypass passage (213a). Thereby, after the first gas flows into the first communication flow path (32) through the first gas inlet (30), it can flow into the inside of the bypass portion (213) through the first bypass passage (213a). Thereafter, the first gas can flow along the inside of the bypass portion (213) and then flow into the inside of the mid-body (210) through the second bypass passage (213b). The second communication flow path (33) communicates the first port (31) with the hollow fiber membrane (221). The second communication flow path (33) can be disposed inside the first cap (3). The second communication flow path (33) can be formed by penetrating one end of the first cap (3). When the first cap (3) is coupled to the mid-case (21), the second communication flow path (33) can be connected to communicate with the first mid-passage (210a). Thereby, the second gas can flow in or out between the inside of the first cap (3) and the hollow fiber membrane (221) through the second communication flow path (33) and the first mid-passage (210a). The partition portion (34) spatially separates the first communication flow path (32) and the second communication flow path (33). The partition portion (34) is disposed inside the first cap (3) and can partition the first communication flow path (32) and the second communication flow path (33). Thereby, the partition portion (34) can prevent the first gas and the second gas from being mixed with each other inside the first cap (3). Based on FIG. 10, the first communication flow path (32) is disposed above the partition portion (34), and the second communication flow path (33) is disposed below the partition portion (34), so that the first communication flow path (32) and the second communication flow path (33) can be spatially separated by the partition portion (34). In this case, by disposing a part of the first port (31) so as to cross the first communication flow path (32) and the partition portion (34), the first port (31) can be connected to communicate with the second communication flow path (33). The present invention described above is not limited to the foregoing embodiments and the accompanying drawings, and it will be apparent to those of ordinary skill in the technical field to which the present invention pertains that various substitutions, modifications, and changes are possible without departing from the technical idea of the present invention.

Claims

1. A mid-case provided in a fuel cell humidifier, comprising a humidifying module for humidifying dry gas supplied to a fuel cell stack using wet 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, a mid-body for housing at least one cartridge including a plurality of hollow fiber membranes; and a bypass portion that bypasses the first gas flowing in through the first gas inlet of the first cap and allows it to flow into the cartridge side housed inside the mid-body, wherein the bypass portion protrudes from the mid-body at a position overlapping the cartridge housed inside the mid-body, and is characterized in that it is a mid-case of a fuel cell humidifier.

2. The cross-sectional area of the first mid-passage formed through one end of the mid-body is larger than the cross-sectional area of the first bypass passage formed through one end of the bypass portion, and is characterized in that it is a mid-case of a fuel cell humidifier according to Claim 1.

3. Assuming the cross-sectional area of the first mid-passage is 1, the cross-sectional area of the first bypass passage is 0.1 or more and 0.45 or less, and is characterized in that it is a mid-case of a fuel cell humidifier according to Claim 2.

4. A second bypass passage communicating with the inside of the mid-body is formed in the bypass portion, and the cross-sectional area of the second bypass passage is larger than the cross-sectional area of the first bypass passage, and is characterized in that it is a mid-case of a fuel cell humidifier according to Claim 2.

5. A second bypass passage communicating with the inside of the mid-body is formed in the bypass portion, Assuming the cross-sectional area of the first mid-passage is 1, the cross-sectional area of the second bypass passage is 0.2 or more and 0.8 or less, and is characterized in that it is a mid-case of a fuel cell humidifier according to Claim 2.

6. A humidifying module for humidifying dry gas supplied to a fuel cell stack using wet 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; including the humidifying module includes a mid-case with both ends open and at least one cartridge including a plurality of hollow fiber membranes, the first cap includes a first gas inlet through which the first gas for supplying to the inside of the mid-case flows in, and a first port communicating with the hollow fiber membrane through which the second gas flows in or out. The mid-case includes a mid-body in which the cartridge is housed, and a bypass portion that bypasses the first gas flowing in through the first gas inlet and causes the gas to flow into the side of the cartridge housed inside the mid-body. The fuel cell humidifier is characterized in that the bypass portion protrudes from the mid-body at a position overlapping the cartridge housed inside the mid-body. **Claim 7** The first cap has a first communication flow path that communicates the first gas inlet and the bypass portion; has a second communication flow path that communicates the first port and the hollow fiber membrane; and The fuel cell humidifier according to claim 6, characterized in that it includes a partition portion that spatially separates the first communication flow path and the second communication flow path. **Claim 8** The bypass portion includes a first bypass passage that communicates with the first communication flow path and a second bypass passage that communicates with the inside of the mid-body. The fuel cell humidifier according to claim 7, characterized in that the first bypass passage and the second bypass passage are formed to penetrate the bypass portion in different positions and in different directions from each other. **Claim 9** The first cap includes a first communication flow path that communicates the first gas inlet and the bypass portion, and a second communication flow path that communicates the first port and the hollow fiber membrane. At one end of the bypass portion, a first bypass passage that communicates with the first communication flow path is formed. At one end of the mid-body, a first mid-passage that communicates with the second communication flow path is formed. The fuel cell humidifier according to claim 6, characterized in that the cross-sectional area of the first mid-passage is larger than the cross-sectional area of the first bypass passage. **Claim 10** The fuel cell humidifier according to claim 9, characterized in that when the cross-sectional area of the first mid-passage is set to 1, the cross-sectional area of the first bypass passage is 0.1 or more and 0.45 or less. **Claim 11** A second bypass passage that communicates with the inside of the mid-body is formed in the bypass portion. The fuel cell humidifier according to claim 9, characterized in that the cross-sectional area of the second bypass passage is larger than the cross-sectional area of the first bypass passage. **Claim 12** A second bypass passage that communicates with the inside of the mid-body is formed in the bypass portion. The fuel cell humidifier according to claim 9, characterized in that when the cross-sectional area of the first mid-passage is set to 1, the cross-sectional area of the second bypass passage is 0.2 or more and 0.8 or less. **Claim 13** The mid-case includes a first gas outlet for allowing the first gas flowing out from the cartridge to flow out to the outside of the mid-body. The fuel cell humidifier according to claim 6, wherein the second cap includes a second port communicating with the hollow fiber membrane. **Claim 14** The cartridge an inner case containing the hollow fiber membrane; a second gas inlet for allowing a first gas to flow into the inner case; and The fuel cell humidifier according to claim 13, further comprising a second gas outlet for allowing the first gas to flow out from the inner case at a position separated from the second gas inlet. **Claim 15** The fuel cell humidifier according to claim 6, wherein the first gas inlet and the first port protrude in the same direction as each other.

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