Fuel cell humidifier

Abstract

The present invention relates to a humidifier for a fuel cell that can prevent condensed water from flowing into a fuel cell stack during operation, The humidifier for a fuel cell according to an embodiment of the present invention includes: the housing having an exhaust gas inlet port for receiving exhaust gas discharged from a fuel cell stack and an exhaust gas outlet port for discharging the exhaust gas; a humidification module having first and second ends, the housing having a plurality of hollow fiber membranes; a first cap having an air outlet port for supplying air humidified by the humidification module to the fuel cell stack and connected to the first end; a second cap having an air inlet port for receiving air supplied from the outside and connected to the second end; a bypass tube for transferring condensed water generated in an internal space of the first cap or flowing from the hollow fiber membranes into the internal space of the first cap to an internal space of the housing through which the exhaust gas flows; and a condensation induction section extending from the air outlet port for expanding the humidified air to slow down its speed and induce condensation of the condensed water.

Description

[Technical field]

[0001] The present invention relates to a humidifier for a fuel cell, and more particularly to a humidifier for a fuel cell that can prevent condensed water from flowing into a fuel cell stack during operation. [Background technology]

[0002] A fuel cell is a device that generates electricity by reacting hydrogen fuel with oxygen in the air to produce water. High-purity hydrogen is supplied from a hydrogen storage tank to the anode of the fuel cell stack, and atmospheric air is supplied to the cathode of the fuel cell stack through an air supply device such as a blower. Hydrogen supplied to the fuel cell stack's anode is separated into hydrogen ions and electrons. The hydrogen ions move to the cathode via a polymer electrolyte membrane between the anode and cathode, and the electrons move to the cathode via an external conductor. Oxygen supplied to the cathode of the fuel cell stack combines with the electrons and hydrogen ions to produce water and generate electrical energy. The higher the ionic conductivity of the polymer electrolyte membrane in a fuel cell stack, the better the hydrogen ions can be transferred from the anode to the cathode. The ionic conductivity of the polymer electrolyte membrane is closely related to the water content. That is, the more wet the polymer electrolyte membrane is, the better the hydrogen ions can be transferred from the anode to the cathode. Therefore, when the fuel cell is in operation, it is necessary to continuously supply moisture to the polymer electrolyte membrane to maintain the moisture content at a certain level or higher to prevent a sudden drop in the power generation efficiency of the fuel cell. For this purpose, a humidifier is used that can provide moisture to the air supplied to the air electrode of the fuel cell stack. A fuel cell humidifier humidifies air supplied from the outside with moisture in exhaust gas discharged from the air electrode of the stack, and supplies the humidified air to the air electrode of the stack. Condensation inevitably occurs inside the humidifier when the humidified air comes into contact with the physical structure of the humidifier (e.g., the hollow fiber membrane for humidification, the passage structure through which the humidified air flows, etc.). If condensation flows into a fuel cell stack in operation, it will cause a decrease in power generation efficiency. Therefore, measures must be taken to prevent condensation from flowing into a fuel cell stack in operation.

[0003] U.S. Patent US7,264,233 (hereinafter, "the '233 Patent") discloses a humidifier 1 that can transfer condensate that accumulates in a liquid pool area 33 inside a downstream head 3 through which humidified air flows, to a lead-in manifold 5 through which exhaust gas flows. To this end, the humidifier 1 of the '233 Patent is equipped with a communicating tube 6 that connects the liquid pool area 33, where the condensate accumulates, to the lead-in manifold 5. In other words, it is assumed that the condensate falls by gravity and necessarily accumulates in the liquid pool area 33 inside the downstream head 3. However, the '233 Patent overlooks the points that (i) condensation occurs even in the hollow fiber membrane 42 where humidification takes place, and (ii) when external air is suddenly supplied at high pressure by switching from low current mode to high current mode, the condensed water accumulated in the hollow fiber membrane 42 is discharged from the hollow fiber membrane 42 together with the high pressure air, and then immediately discharged from the humidifier 1 and flows into the fuel cell stack without passing through the lower region inside the downstream head 3. In other words, the '233 Patent still requires a considerable amount of condensed water to flow into the fuel cell stack during operation, and fails to prevent the resulting decrease in power generation efficiency. In addition, the transmission passage 6 of the '233 Patent formed on the downstream head 3 is exposed to the outside, so there is a high risk of condensation water freezing inside the communicating tube 6 in extremely cold environments. Such freezing of condensation water inside the communicating tube 6 prevents condensation water accumulated in the lower area (liquid pool area) 33 inside the downstream head 3 from escaping from the lower area (liquid pool area) 33 through the communicating tube 6, resulting in the condensation water flowing into the fuel cell stack and causing a decrease in power generation efficiency.

[0004] Meanwhile, Korean Patent Publication No. 2018-0109108 (hereinafter "Patent 108") was disclosed, which addressed the issues of US Patent US7,264,233. Patent 108 proposes a bypass tube for transferring condensed water generated in the first cap on the fuel cell stack side or that has flowed into the first cap to the internal space of the housing through which exhaust gas flows, and a rib or a thread structure that can replace the rib provided in the air exhaust port to prevent the condensed water from being transferred to the fuel cell stack through the air exhaust port. According to the '108 Patent, some of the condensed water contained in the humidified air flowing into the fuel cell stack can be removed by the ribs (or thread structure), but there is a limitation in that the condensed water contained in the humidified air that does not pass near the ribs (or thread structure) cannot be removed. In other words, there is a limitation in that the condensed water contained in the humidified air flowing through the fuel cell stack and flowing in the portion adjacent to the inner circumferential surface of the air exhaust port can be removed, but the condensed water contained in the humidified air flowing through the center portion of the air exhaust port cannot be removed. Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention relates to a humidifier for a fuel cell that can avoid problems caused by the limitations and shortcomings of the related art as described above, and aims to provide a humidifier for a fuel cell that can prevent condensed water from flowing into a fuel cell stack during operation. [Means for solving the problem]

[0006] The humidifier for a fuel cell according to an embodiment of the present invention includes: the housing having an exhaust gas inlet port for receiving exhaust gas discharged from a fuel cell stack and an exhaust gas outlet port for discharging the exhaust gas; a humidification module having first and second ends, the housing having a plurality of hollow fiber membranes disposed therein; a first cap having an air outlet port for supplying air humidified by the humidification module to the fuel cell stack and connected to the first end; a second cap having an air inlet port for receiving air supplied from the outside and connected to the second end; a bypass tube for transferring condensed water generated in an internal space of the first cap or flowing from the hollow fiber membranes into the internal space of the first cap to an internal space of the housing through which the exhaust gas flows; and a condensation induction section extending from the air outlet port for expanding the humidified air to slow down its speed and induce condensation of the condensed water. In the humidifier for a fuel cell according to an embodiment of the present invention, the condensation inducer may be a hollow structure having a diameter larger than a diameter of the air exhaust port. In the humidifier for a fuel cell according to an embodiment of the present invention, the condensation inducer may be a hollow structure having a cross-sectional area larger than a cross-sectional area of ​​the air exhaust port. In the humidifier for a fuel cell according to an embodiment of the present invention, the air exhaust port and the condensation inducer may be inclined at a preset angle toward the fuel cell stack. In the humidifier for a fuel cell according to an embodiment of the present invention, a rib may be formed within the air exhaust port to prevent condensed water from being transferred to the fuel cell stack through the air exhaust port. In the humidifier for a fuel cell according to an embodiment of the present invention, the condensation inducer is formed at the rear end of the rib, and can induce condensation of condensed water that cannot be removed by the rib and remove it.

[0007] In the fuel cell humidifier according to the embodiment of the present invention, the inner surface of the air exhaust port may be formed with a screw thread that provides a helical path for the condensed water. In the humidifier for a fuel cell according to an embodiment of the present invention, the condensation inducer is formed at a rear end of the thread, and can induce condensation and remove condensed water that could not be removed by the thread. In a humidifier for a fuel cell according to an embodiment of the present invention, the bypass tube comprises a first tube fixed to the first cap and a second tube fixed to the humidification module, and the first and second tubes can be detachably coupled. Further details, such as implementations of various aspects of the present invention, are included in the following detailed description. Effect of the Invention

[0008] According to the embodiment of the present invention, it is possible to prevent condensed water from flowing into the fuel cell stack during operation, and to prevent a decrease in power generation efficiency due to the flow of condensed water into the fuel cell stack. In addition, the condensation inducer, which is one component of the present invention, can increase the relative humidity of the humidified air and remove condensed water contained in the humidified air flowing through the center of the air exhaust port, thereby more effectively preventing a decrease in power generation efficiency due to condensed water flowing into the fuel cell stack. [Brief description of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view of a humidifier for a fuel cell according to a first embodiment of the present invention. [Diagram 2] FIG. 4 is a cross-sectional view of a humidifier for a fuel cell according to a second embodiment of the present invention. [Diagram 3] FIG. 11 is a cross-sectional view showing a part of a humidifier for a fuel cell according to a third embodiment of the present invention. [Figure 4] 11 is a cross-sectional view showing an alternative embodiment of a bypass tube. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present invention can be modified in various ways and can have various embodiments, and a specific embodiment will be illustrated and described in detail in the detailed description. However, this is not intended to limit the present invention to the specific embodiment, and it should be understood that the present invention includes all modifications, equivalents, and alternatives within the spirit and technical scope of the present invention. The terms used in the present invention are merely used to describe certain embodiments and are not intended to limit the present invention. A singular expression includes a plural expression unless the context clearly indicates otherwise. In this specification, the terms "include" or "have" are intended to specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and should be understood not to preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof. Hereinafter, a fuel cell humidifier according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a humidifier for a fuel cell according to a first embodiment of the present invention, FIG. 2 is a cross-sectional view of a humidifier for a fuel cell according to a second embodiment of the present invention, FIG. 3 is a cross-sectional view showing a portion of a humidifier for a fuel cell according to a third embodiment of the present invention, and FIG. 4 is a cross-sectional view showing an alternative embodiment of a bypass tube.

[0011] The fuel cell humidifier 100 of the present invention is a device that humidifies air supplied from the outside with moisture in the off-gas discharged from the fuel cell stack S and supplies the humidified air to the fuel cell stack S. As shown in FIG. 1, the humidifier 100 of the present invention comprises a humidification module 110 having first and second ends 110a, 110b, a first cap 120 coupled to the first end 110a and having an air outlet port OP1 for supplying humidified air to a fuel cell stack S, and a second cap 130 coupled to the second end 110b and having an air inlet port IP1 for receiving air supplied from the outside. The humidification module 110 includes a housing 111 and a plurality of hollow fiber membranes 112 disposed within the housing 111. The housing 111 has an exhaust gas inlet port IP2 for receiving exhaust gas from the fuel cell stack S and an exhaust gas outlet port OP2 for discharging the exhaust gas. As shown in FIG. 1, a housing 111 according to one embodiment of the present invention comprises a first housing 111a containing a hollow fiber membrane 112, and a second housing 111b surrounding the first housing 111a and having an exhaust gas inlet port IP2 and an exhaust gas outlet port OP2, and the first housing 111a has a first group of openings H1 corresponding to the exhaust gas inlet port IP2 and a second group of openings H2 corresponding to the exhaust gas outlet port OP2. Both ends of the hollow fiber membrane 112 are potted in first fixing layers 113 formed in both ends of the first housing 111a, respectively, and both ends of the first housing 111a are fixed to both ends of the second housing 111b via a second fixing layer 114. The second fixing layer 114 can be a gasket assembly that hermetically connects the first housing 111a and the second housing 111b together via a mechanical assembly.

[0012] Alternatively, the housing 111 of the present invention may be a single housing containing the hollow fiber membrane 112. In this case, both ends of the hollow fiber membrane 112 may be potted in fixing layers formed in both ends of the single housing, respectively. According to another embodiment of the present invention, the hollow fiber membrane 112 may include two or more hollow fiber membrane bundles, and the housing 111 may include two or more first housings 111a each containing two or more hollow fiber membrane bundles, and a second housing 111b surrounding the first housing 111a and having an exhaust gas inlet port IP2 and an exhaust gas outlet port OP2, and each of the first housings 111a may have a first group of openings H1 corresponding to the exhaust gas inlet port IP2 and a second group of openings H2 corresponding to the exhaust gas outlet port OP2. According to the present invention, the internal space of the first cap 120 and the internal space of the second cap 130 are in fluid communication with each other only through the lumens of the hollow fiber membrane 112. The internal space of the first cap 120 is defined by the inner surface of the first cap 120 and the first end 110a of the humidification module 110, and the internal space of the second cap 130 is defined by the inner surface of the second cap 130 and the second end 110b of the humidification module 110. The exhaust gas flowing into the housing 111 through the exhaust gas inlet port IP2 comes into contact with the hollow fiber membranes 112 while flowing within the internal space of the housing 111, and is then discharged to the outside of the housing 111 through the exhaust gas outlet port OP2.

[0013] Air that flows into the internal space of the second cap 130 from the outside through the air inlet port IP1 flows into the internal space of the first cap 120 through the hollow of the hollow fiber membrane 112, and is then supplied to the fuel cell stack S through the air outlet port OP1. As air flows along the hollow of the hollow fiber membrane 112, moisture contained in the exhaust gas flowing through the internal space of the housing 111 passes through the hollow fiber membrane 112 and is transferred to the air, thereby humidifying the air. The humidified air flows into the internal space of the first cap 120 and is then supplied to the fuel cell stack S via the air exhaust port OP1. As described above, condensed water generated when humidified air condenses within the hollow fiber membrane 112 or within the internal space of the first cap 120 must be prevented from flowing into the fuel cell stack S. To this end, as shown in FIG. 1, the humidifier 100 for a fuel cell according to the present invention further includes a bypass tube 140 and a condensation inducer 150. The bypass tube 140 transfers condensed water that is generated in the internal space of the first cap 120 or that flows from the hollow fiber membrane 112 into the internal space of the first cap 120 to the internal space of the housing 111 through which the exhaust gas flows. According to the present invention, one end of the bypass tube 140 is located in the air exhaust port OP1, and the other end of the bypass tube 140 is located in the internal space (i.e., the space through which the exhaust gas flows) of the housing 111. Condensed water entering the air exhaust port OP1 flows into the internal space of the housing 111 along the bypass tube 140 due to the air pressure difference. Condensed water generated in the internal space of the first cap 120 or flowing from the hollow fiber membrane 112 into the internal space of the first cap 120 passes through the air exhaust port OP1 of the first cap 120 to move to the fuel cell stack. Therefore, by positioning one end of the bypass tube 140 within the air exhaust port OP1, it is possible to primarily prevent the condensed water generated due to condensation of humidified air from flowing into the fuel cell stack.

[0014] 1, the bypass tube 140 may be disposed in the internal space of the first cap 120 and the internal space of the housing 111 so as not to be exposed to the outside. If the bypass tube 140 is not exposed to the outside, condensed water may be prevented from freezing in the bypass tube 140 even in a cold environment. Therefore, the condensed water may not be able to bypass due to freezing in the bypass tube 140, and may be prevented from flowing into the fuel cell stack. As shown in FIG 1, a rib 121 may be provided in the air exhaust port OP1 to prevent the condensed water from being transferred to the fuel cell stack through the air exhaust port OP1. The rib 121 prevents a portion of the condensed water that has entered the air exhaust port OP1 from flowing toward the fuel cell stack. The condensed water that is prevented from flowing by the rib 121 accumulates under the rib 121. Therefore, as shown in FIG 1, one end of the bypass tube 140 may be located adjacent to the rib 121. That is, one end of the bypass tube 140 may be located between the first rib 121 and the boundary between the body of the first cap 120 and the air exhaust port OP1. As mentioned above, some of the condensed water contained in the humidified air flowing into the fuel cell stack can be removed by the ribs 121, but there is a limitation in that condensed water contained in the humidified air that does not pass near the ribs 121 cannot be removed.

[0015] Accordingly, the first embodiment of the present invention further includes a condensation inducer 150 formed at the rear end of the rib 121 and capable of instantly expanding the humidified air to slow down the speed and induce condensation of condensed water. Condensation inducer 150 may be a hollow structure extending from air exhaust port OP1 and having a diameter (or cross-sectional area) larger than the diameter (or cross-sectional area) of air exhaust port OP1. Condensation inducer 150 may be an arc-shaped structure having a diameter larger than the diameter of air exhaust port OP1. Of course, the shape of condensation inducer 150 is not limited thereto and may be any shape, but it is sufficient that the diameter or cross-sectional area is larger than the diameter or cross-sectional area of ​​air exhaust port OP1. In the following description, when only the "diameter" or only the "cross-sectional area" is mentioned, it can all mean the "diameter or cross-sectional area". The condensation inducer 150 induces a sudden adiabatic expansion of the humidified air flowing into the fuel cell stack S, and uses the inherent energy of the humidified air in the form of work, thereby lowering the temperature according to the first law of energy. When the temperature of the humidified air decreases, the saturated humidity at that temperature decreases, and the relative humidity increases accordingly. Due to the increased relative humidity, some of the condensed humidified air becomes larger as the condensed water contained in the humidified air becomes condensation nuclei, and falls down to accumulate on the bottom of the condensation inducer 150. In this manner, the condensation inducer 150 increases the relative humidity of the humidified air, thereby making it possible to remove condensed water contained in the humidified air flowing through the central portion of the air exhaust port OP1. On the other hand, if condensation is allowed to accumulate on the bottom surface of condensation inducer 150, the effective flow cross-sectional area of ​​condensation inducer 150 may be reduced, and the magnitude of adiabatic expansion may be reduced, so it is preferable for condensation inducer 150 to maintain its originally designed cross-sectional area.

[0016] 2, the air exhaust port OP1 of the first cap 120 according to the second embodiment of the present invention may be inclined at a preset angle toward the fuel cell stack S. The condensation inducer 150 is formed to extend from the air exhaust port OP1, and its central axis may be inclined at a preset angle toward the fuel cell stack S, similar to the air exhaust port OP1. As shown in FIG. 2, the air exhaust port OP1 and the condensation guide unit 150 are inclined at a preset angle toward the fuel cell stack S, thereby preventing condensed water from accumulating on the bottom surface of the condensation guide unit 150. The condensed water condensed in the condensation guide portion 150 flows down along the air exhaust port OP1 and flows into the internal space of the housing 111 via the bypass tube 140 due to the pressure difference. On the other hand, in order to be able to block the flow of condensed water, not only is it necessary for the ribs 121 to be of a certain size, but they also have a surface perpendicular to the flow of humidified air, which may impose excessive resistance on the flow of humidified air and reduce the power generation efficiency of the fuel cell. 3, a first cap 120 according to a third embodiment of the present invention may include a screw thread 122 formed on the inner surface of the air exhaust port OP1. The screw thread 122 provides a spiral path for the condensed water flowing into the air exhaust port OP1.

[0017] The thread 122 may be substituted for the above-mentioned rib 121. That is, the thread 122 of the present invention may also be formed on the inner surface of the air outlet port OP1 extending in a direction parallel to the longitudinal direction of the hollow fiber membrane 112. As shown in Fig. 3, if the air outlet port OP1 is inclined so that the humidified air can flow upward at a predetermined angle, it is more advantageous in that the condensed water flowing into the air outlet port OP1 can be guided by the thread 122. In order to transmit the condensed water that flows into the air exhaust port OP1 and reaches the termination portion of the thread 122 via a helical path to the internal space of the housing 111, one end of the bypass tube 140 can be located adjacent to the terminal portion of the thread 122. That is, one end of the bypass tube 140 can be arranged so as to be able to receive the condensed water that has migrated to the terminal portion of the thread 122 via a helical path. However, as mentioned above, while some of the condensed water contained in the humidified air flowing into the fuel cell stack S can be removed by the threads 122, there is a limitation in that condensed water contained in the humidified air that does not pass near the threads 122 cannot be removed. Accordingly, the third embodiment of the present invention further includes a condensation inducer 150 formed at the rear end of the thread 122 and capable of instantly expanding the humidified air to slow down the speed and induce condensation of condensed water. As in the second embodiment, the air exhaust port OP1 and the condensation guide unit 150 are inclined at a preset angle toward the fuel cell stack S. Condensed water condensed in the condensation guide unit 150 flows down along the air exhaust port OP1 and flows into the interior space of the housing 111 through the bypass tube 140 due to a pressure difference.

[0018] According to the third embodiment of the present invention, not only can excessive resistance to the flow of humidified air be prevented, which would otherwise reduce the power generation efficiency of the fuel cell, but condensed water contained in the humidified air that does not pass near the screw thread 122 can also be removed. The bypass tube 140 of the present invention shown in Figures 1-3 can be a single monolithic tube. 4, the bypass tube 140 of the present invention may include a first tube 141 fixed to the first cap 120 and a second tube 142 fixed to the humidification module 110, and the first and second tubes 141, 142 may be detachably coupled. That is, when the first cap 120 is coupled to the humidification module 110, the first tube 141 may also be coupled to the second tube 142, which may improve the convenience and productivity of the manufacturing process of the humidifier 100. Although one embodiment of the present invention has been described above, a person having ordinary knowledge in the art would be able to modify and change the present invention in various ways by adding, changing, deleting, or adding components without departing from the concept of the present invention described in the claims, and this would also be considered to be within the scope of the claims of the present invention. [Explanation of symbols]

[0019] 100: Humidifier for fuel cell 110: Humidification module 111: Housing 111a: First housing 111b: second housing 112: hollow fiber membrane 113: First fixed layer 114: Second fixed layer 120: 1st cap 121: rib 122: Thread 130: Second cap 140: Bypass tube 150: Condensation induction section

Claims

1. a humidification module including a housing having an exhaust gas inlet port for receiving exhaust gas discharged from a fuel cell stack and an exhaust gas outlet port for discharging the exhaust gas, and a plurality of hollow fiber membranes disposed within the housing, the humidification module having first and second ends; a first cap coupled to the first end and having an air exhaust port for supplying air humidified by the humidification module to the fuel cell stack; a second cap coupled to the second end, the second cap having an air inlet port for receiving air supplied from an external source; a bypass tube for transmitting condensed water generated in the internal space of the first cap or flowing from the hollow fiber membrane into the internal space of the first cap to the internal space of the housing through which the exhaust gas flows; a condensation inducer extending from the air exhaust port and expanding the humidified air to retard its speed and induce condensation of condensed water; the condensation inducer is an arc-shaped hollow structure having a diameter larger than a diameter of the air exhaust port; the air exhaust port and the condensation inducer are inclined at a preset angle toward the fuel cell stack; Humidifier for fuel cells.

2. The condensation inducer includes:

2. The humidifier for a fuel cell according to claim 1, which is a hollow structure having a cross-sectional area larger than a cross-sectional area of ​​the air exhaust port.

3. A humidifier for a fuel cell as described in any one of claims 1 to 2, wherein a rib is formed within the air exhaust port to prevent condensed water from being transmitted to the fuel cell stack through the air exhaust port.

4. The condensation inducer includes:

4. The humidifier for a fuel cell according to claim 3, wherein the condensed water formed at the rear end of the rib and unable to be removed by the rib is induced to condense and removed.

5. 3. The fuel cell humidifier according to claim 1, wherein the inner surface of the air exhaust port is formed with a screw thread that provides a helical path for the condensed water.

6. The condensation inducer includes:

6. The humidifier for a fuel cell according to claim 5, wherein a condensation layer is formed at a rear end of the thread, and the condensation water that could not be removed by the thread is induced to condense and removed.

7. The bypass tube is 2. The humidifier for a fuel cell as described in claim 1, comprising a first tube fixed to the first cap and a second tube fixed to the humidification module, the first and second tubes being detachably coupled.

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