Fuel cell humidifier of which hollow fiber membranes can be length-adjusted, and fuel cell humidifier of which gaps between hollow fiber membranes can adjusted

Abstract

The present invention relates to a fuel cell humidifier of which hollow fiber membranes can be length-adjusted or of which gaps between the hollow fiber membranes can be adjusted in response to a humidifier internal temperature that changes according to the output state of a fuel cell, the humidifier comprising: a housing; the hollow fiber membranes, which are positioned inside the housing, have dry air flowing therein, and have wet air flowing at the outside thereof; and potting materials positioned at both ends of the hollow fiber membranes so as to fix the ends of the hollow fiber membranes, wherein the potting materials, into which a first temperature-sensitive volume change member that expands and contracts according to temperature is inserted, are divided, with respect to the first temperature-sensitive volume change member, into an inner potting material positioned inside the housing and an outer potting material positioned outside the housing and spaced apart from the inner potting material.

Description

A fuel cell humidifier with adjustable hollow fiber membrane length and a fuel cell humidifier with adjustable clearance between hollow fiber membranes

[0001] The present invention relates to a humidifier for a fuel cell. More specifically, the present invention relates to a humidifier for a fuel cell in which the length of a hollow fiber membrane or the spacing between hollow fiber membranes is adjusted in response to the internal temperature of the humidifier, which changes depending on the output status of the fuel cell.

[0002] A fuel cell is a power-generating battery that combines hydrogen and oxygen to produce electricity. Unlike conventional chemical cells like batteries or accumulators, fuel cells can continuously produce electricity as long as hydrogen and oxygen are supplied. They also have the advantage of being approximately twice as efficient as internal combustion engines, as they eliminate heat loss.

[0003] Furthermore, because they directly convert the chemical energy generated by the combination of hydrogen and oxygen into electrical energy, they produce low emissions. Therefore, fuel cells are not only environmentally friendly but also offer the advantage of reducing concerns about resource depletion due to increased energy consumption.

[0004] Fuel cells are classified according to the type of electrolyte used, and among these, polymer electrolyte fuel cells are known to be the most promising not only for small-scale stationary power generation equipment but also for transportation systems because they operate at lower temperatures than other fuel cells and have a high power density, allowing for miniaturization.

[0005] One of the most important factors in improving the performance of polymer electrolyte fuel cells is maintaining the moisture content of the polymer electrolyte membrane (or proton exchange membrane: PEM) of the membrane electrode assembly (MEA) by supplying a certain amount of moisture. This is because if the polymer electrolyte membrane dries, its power generation efficiency rapidly declines.

[0006] Therefore, the role of humidifiers that humidify with polymer electrolyte membranes is essential and crucial. Among these, membrane humidification, which utilizes a membrane that selectively transmits only water vapor, is advantageous in that it allows for lighter and more compact humidifiers.

[0007] In particular, the selective permeable membrane used in humidifying membranes is preferably a hollow fiber membrane with a large permeable area per unit volume when forming modules. This means that manufacturing a humidifier using hollow fiber membranes allows for high integration of the membranes with a large contact surface area, enabling sufficient humidification of the fuel cell even with small capacities.

[0008] However, there are limitations that arise from densely embedding bundles of hollow fiber membranes in the housing to achieve high integration of the hollow fiber membranes and potting both ends of the hollow fiber membranes.

[0009] First, Fig. 1 is a perspective view of a typical fuel cell membrane humidifier (1). Caps (3) are provided at both ends of the housing (2), and a bundle of hollow fiber membranes (4) is built into the housing (2) and fixed by a potting material (5).

[0010] One cap (3) is provided with a dry air inlet (6-1), and the other cap (3) is provided with a dry air outlet (6-2). Dry air entering through the dry air inlet (6-1) passes through the hollow fiber membrane (4) and is discharged through the dry air outlet (6-2) to be introduced into the stack (not shown) of the fuel cell.

[0011] The outer surface of the housing (2) is provided with a wet air inlet (7-1) and a wet air outlet (7-2), and the unreacted wet gas discharged from the stack flows into the housing (2) through the wet air inlet (7-1), humidifies the dry air flowing inside the hollow fiber membrane (4), and is discharged through the wet air outlet (7-2).

[0012] Next, Fig. 2 is a cross-sectional view of the membrane humidifier for a fuel cell of Fig. 1 taken along line II`. Referring to Fig. 2, problems with a typical membrane humidifier for a fuel cell can be identified.

[0013] In order to achieve high integration, a membrane humidifier (1) for a fuel cell has a bundle of hollow fiber membranes (4) built into a housing (2), and both ends of the hollow fiber membranes (4) are fixed to a potting material (5).

[0014] At this time, the hollow fiber membrane (4) is formed of a polymer material, and when exposed to a high temperature and high humidity environment in which the humidifier (1) is operated, the length of the hollow fiber membrane (4) increases, and the increased hollow fiber membrane (4) vibrates due to the flow of air introduced.

[0015] As the length of the hollow fiber membrane (4) increases, the vibration amplitude increases and the stress intensity applied to the hollow fiber membrane (4) increases, which increases the possibility of damage to the hollow fiber membrane (4). Therefore, it is important to appropriately reduce or stretch the increased length of the hollow fiber membrane (4) to prevent vibration. However, the hollow fiber membrane (4) is fixed at both ends by a potting material (5), and the potting material (5) is fixed to the housing (2), which makes it difficult to change the length.

[0016] Another problem is that, referring again to Fig. 1, the hollow fiber membrane (4) is built into the housing (2) in the form of a bundle, and humidification due to the inflow of moist air occurs mainly on the outside of the bundle of hollow fiber membranes (4), and there is a problem that the inside of the bundle is not sufficiently humidified.

[0017] In this way, technological development is still needed to improve the humidification efficiency and durability of membrane humidifiers for fuel cells.

[0018] The present invention is intended to solve the above-described problems and to provide a membrane humidifier for a fuel cell capable of adjusting the length of a hollow fiber membrane according to the operating state of the fuel cell.

[0019] In addition, the purpose is to provide a membrane humidifier for a fuel cell capable of adjusting the gap between hollow fiber membranes according to the operating status of the fuel cell.

[0020] In order to solve the above-described problem, the present invention provides a membrane humidifier for a fuel cell capable of adjusting the length of a hollow fiber membrane, comprising: a housing; a hollow fiber membrane positioned inside the housing, through which dry air flows inside and wet air flows outside; and a potting material positioned at both ends of the hollow fiber membrane to fix the ends of the hollow fiber membrane; and the potting material has a first temperature-sensitive volume-changing member inserted therein that expands and contracts according to temperature, and can be divided into an inner potting material positioned inside the housing and an outer potting material positioned outside the housing and spaced apart from the inner potting material based on the first temperature-sensitive volume-changing member.

[0021] In one embodiment of the present invention, the inner potting material is spaced apart from the housing with a gap therebetween, and can move in the longitudinal direction of the hollow fiber membrane according to expansion and contraction of the first temperature-sensitive volume change member.

[0022] In one embodiment of the present invention, the outer potting material can be fixed to the housing.

[0023] In one embodiment of the present invention, the first temperature-sensitive volume change member can contract as the temperature increases and expand as the temperature decreases.

[0024] In one embodiment of the present invention, the first temperature-sensitive volume change member is selected from the group consisting of poly(N-isopropylacrylamide) (poly(N-isopropylacrylamide), poly(NIPAM)), poly(N-isopropyl acrylamide-co-allylamine) (poly(N-isopropyl acrylamide-co-allylamine), poly(NIPAM-co-AA)), poly(N-isopropyl acrylamide-co-2-(dimethylamino)ethyl methacrylate) (poly(N-isopropyl acrylamide-co-DMAEMA)), poly(N-isopropyl acrylamide-co-2-(dimethylamino)ethyl acrylate) (poly(NIPAM-co-DMAEA)), poly(N-isopropyl It may include at least one selected from the group consisting of poly(N-isopropyl acrylamide-co-acrylic acid), poly(NIPAM-co-AAc), poly(N-isopropyl acrylamide-co-methacrylic acid), poly(NIPAM-co-MAAc), poly(N,N-diethylacrylamide), poly(N-vinylcaprolactam), poly(ethylene glycol), and poly(ethylene glycol-b-propylene glycol-b-ethylene glycol).

[0025] Another embodiment of the present invention for solving the above-described problem comprises a membrane humidifier for a fuel cell capable of adjusting a clearance between hollow fiber membranes, the membrane humidifier comprising a housing, a hollow fiber membrane positioned inside the housing, a first fluid flowing inside and a second fluid flowing outside, and a potting material positioned at both ends of the hollow fiber membranes to fix the ends of the hollow fiber membranes, wherein the potting material is divided into a plurality of pieces by inserting a second temperature-sensitive volume-changing member that expands and contracts according to temperature, and each of the divided pieces may move away from or closer to each other with respect to an axis parallel to the longitudinal direction of the hollow fiber membranes according to the expansion and contraction of the temperature-sensitive volume-changing member.

[0026] In one embodiment of the present invention, a third temperature-sensitive volume change member that surrounds the potting material and expands and contracts depending on temperature may be inserted between the potting material and the housing.

[0027] In one embodiment of the present invention, the second temperature-sensitive volume change member may expand as the temperature increases and contract as the temperature decreases.

[0028] In one embodiment of the present invention, the second temperature-sensitive volume change member may have a thermal expansion coefficient that is 50% or more greater than the thermal expansion coefficient of the potting material.

[0029] In one embodiment of the present invention, the third temperature-sensitive volume change member may contract as the temperature increases and expand as the temperature decreases.

[0030] In one embodiment of the present invention, the third temperature-sensitive volume change member is poly(N-isopropyl acrylamide) (poly(N-isopropylacrylamide), poly(NIPAM)), poly(N-isopropyl acrylamide-co-allylamine) (poly(N-isopropyl acrylamide-co-allylamine), poly(NIPAM-co-AA)), poly(N-isopropyl acrylamide-co-2-(dimethylamino)ethyl methacrylate) (poly(N-isopropyl acrylamide-co-2-(dimethylamino)ethyl methacrylate), poly(NIPAM-co-DMAEMA)), poly(N-isopropyl acrylamide-co-2-(dimethylamino)ethyl acrylate), poly(NIPAM-co-DMAEA)), poly(N-isopropyl It may include at least one selected from the group consisting of poly(N-isopropyl acrylamide-co-acrylic acid), poly(NIPAM-co-AAc), poly(N-isopropyl acrylamide-co-methacrylic acid), poly(NIPAM-co-MAAc), poly(N,N-diethylacrylamide), poly(N-vinylcaprolactam), poly(ethylene glycol), and poly(ethylene glycol-b-propylene glycol-b-ethylene glycol).

[0031] The present invention has the advantage of improving the durability of a membrane humidifier for a fuel cell by adjusting the length of the hollow fiber membrane according to the operating state of the fuel cell according to the above-described configuration and bonding relationship, thereby alleviating stress on the hollow fiber membrane.

[0032] In addition, the gap between the hollow fiber membranes is adjusted according to the operating status of the fuel cell, so that effective humidification is achieved up to the inside of the hollow fiber membrane bundle in the high-power operating section of the fuel cell, and in the low-power operating section of the fuel cell, there is an advantage in that the humidification efficiency can be reduced, thereby reducing the occurrence of condensation.

[0033] Figure 1 is a perspective view of a typical membrane humidifier for fuel cells.

[0034] Fig. 2 is a cross-sectional view of the membrane humidifier for fuel cell of Fig. 1 taken along line II`.

[0035] Figure 3a is a perspective view illustrating one embodiment of a membrane humidifier for a fuel cell capable of adjusting the length of a hollow fiber membrane according to the present invention. Figure 3b is a partially enlarged view of one embodiment of a membrane humidifier for a fuel cell capable of adjusting the length of a hollow fiber membrane according to the present invention.

[0036] Figure 4 is a cross-sectional view taken along line II` of Figure 3a.

[0037] Figure 5 is a partially enlarged view of the cross-sectional view of Figure 4.

[0038] FIG. 6 is a partially enlarged view showing the difference according to temperature in one embodiment of a membrane humidifier for a fuel cell capable of adjusting the length of a hollow fiber membrane according to the present invention.

[0039] Figure 7a is a perspective view of one embodiment of a membrane humidifier for a fuel cell capable of adjusting the clearance between hollow fiber membranes according to the present invention. Figure 7b is a partially enlarged view of one embodiment of a membrane humidifier for a fuel cell capable of adjusting the clearance between hollow fiber membranes according to the present invention.

[0040] Fig. 8 is a cross-sectional view showing the difference according to temperature for a cross-section cut along the line II-II` in Fig. 7. Fig. 8a is a cross-sectional view in a relatively low-temperature environment due to low-power operation of the fuel cell, and Fig. 8b is a cross-sectional view in a relatively high-temperature environment due to high-power operation of the fuel cell. Fig. 9 is a cross-sectional view showing a modified embodiment of a membrane humidifier for a fuel cell capable of adjusting the clearance between hollow fiber membranes according to the present invention.

[0041] This specification clarifies the scope of the present invention and explains the principles of the invention and discloses embodiments thereof to enable those skilled in the art to practice the invention. The disclosed embodiments may be implemented in various forms.

[0042] Expressions such as “include” or “may include” that may be used in various embodiments of the present invention indicate the existence of the disclosed function, operation, or component, etc., and do not limit one or more additional functions, operations, or components, etc. In addition, in various embodiments of the present invention, it should be understood that terms such as “include” or “have” indicate the existence of a feature, number, step, operation, component, part, or combination thereof described in the specification, and do not exclude in advance the possibility of the existence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0043] When a component is referred to as being "connected, coupled" to another component, it should be understood that while the component may be directly connected or coupled to the other component, there may also be a new component between the component and the other component. Conversely, when a component is referred to as being "directly connected" or "directly coupled" to another component, it should be understood that no new component exists between the component and the other component.

[0044] The terms "first," "second," etc., used herein may be used to describe various components, but the components should not be limited by the terms. The terms are used solely to distinguish one component from another.

[0045] Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the drawings.

[0046] FIG. 3a is a perspective view showing one embodiment of a membrane humidifier for a fuel cell capable of adjusting the length of a hollow fiber membrane according to the present invention. FIG. 3b is a partially enlarged view of one embodiment of a membrane humidifier for a fuel cell capable of adjusting the length of a hollow fiber membrane according to the present invention. FIG. 4 is a cross-sectional view taken along line II` of FIG. 5 is a partially enlarged view of the cross-sectional view of FIG. 4. FIG. 6 is a partially enlarged view showing the difference according to temperature in one embodiment of a membrane humidifier for a fuel cell capable of adjusting the length of a hollow fiber membrane according to the present invention.

[0047] Referring to FIG. 3A, one embodiment according to the present invention comprises a housing (100), caps (110) positioned on both sides of the housing, a dry air inlet (120) provided in one cap (110) through which dry air is introduced, a dry air outlet (130) provided in the other cap (110) so that dry air introduced through the dry air inlet (120) is discharged through a hollow fiber membrane (200), a wet air inlet (140) provided on the outer surface of the housing (100) so that wet air discharged from a stack (not shown) of a fuel cell is introduced into the housing (100), a wet air outlet (150) through which wet air humidified inside the housing (100) is discharged, and a dry air outlet (150) located inside the housing (100) through which dry air introduced through the dry air inlet (120) flows inside and dry air introduced through the wet air inlet (140) flows outside. It may include a hollow fiber membrane (200) through which moist air flows and humidification is performed between moist air and dry air with the membrane between them, and a potting material (300) positioned at both ends of the hollow fiber membrane (200) to fix the ends of the hollow fiber membrane (200).

[0048] The housing (100) protects the hollow fiber membrane (200) by embedding it, and forms the exterior of the membrane humidifier (10). The shape is not limited to the square pillar shape illustrated in Fig. 3a and may be provided in various forms. For example, it may be provided in a circular pillar shape, a polygonal pillar shape, or a polyhedral shape, but is not limited thereto.

[0049] The cap (110) is provided on both sides of the housing (100), and is separated from the housing (100) through which moist air flows, and dry air flows inside, and the shape can be provided in various ways.

[0050] Referring to FIGS. 3b and 4, the hollow fiber membrane (200) crosses the housing (100), and one end is connected to the interior of the cap (110) on the dry air inlet (120) side, and the other end is connected to the interior of the cap (110) on the dry air outlet (130) side.

[0051] At both ends of the hollow fiber membrane (200), a potting material (300) is provided to fix the ends of the hollow fiber membrane (200). The potting material (300) fixes the ends of the hollow fiber membrane (200) or a bundle of hollow fiber membranes (200), and at the same time, all or part of the potting material is connected to the housing (100), so that the hollow fiber membrane (200) is fixed and positioned at a predetermined position inside the housing (100).

[0052] In one embodiment of a membrane humidifier (10) for a fuel cell capable of controlling the length of a hollow fiber membrane according to the present invention, a first temperature-sensitive volume change member (400) that expands and contracts depending on temperature can be inserted into the interior of a potting material (300).

[0053] In addition, the potting material (300) is separated by insertion of the first temperature-sensitive volume change member (400), and can be divided into an inner potting material (310) located inside the housing (100) and an outer potting material (320) located outside the housing (100) based on the first temperature-sensitive volume change member (400).

[0054] At this time, the inside of the housing (100) can be understood to mean a side close to the inside of the housing (100) through which moist air flows, and the outside of the housing (100) can be understood to mean a side close to the inside of the cap (110) through which dry air flows.

[0055] For example, the potting material (300) may be provided in the form of a plate having a predetermined thickness and being perpendicular to the longitudinal direction of the hollow fiber membrane (200) (x-axis in FIGS. 3b and 4), and the first temperature-sensitive volume change member (400) may also be provided in the form of a plate having a thickness that is thinner than the potting material (300) and being perpendicular to the longitudinal direction of the hollow fiber membrane (200) (x-axis in FIGS. 3b and 4) and may be inserted into the potting material (300), and accordingly, the potting material (300) may be separated into two plates, one of which may be positioned on one side of the first temperature-sensitive volume change member (400) (+x direction in FIG. 3b or 4), and the other may be positioned on the other side of the first temperature-sensitive volume change member (400) (-x direction in FIG. 3b or 4).

[0056] Referring to FIG. 5, in one embodiment of the present invention, the outer potting material (320) can be fixed to the housing (100), and the inner potting material (310) can be spaced apart from the housing (100) with a gap (S) therebetween.

[0057] The outer potting material (320) enables the hollow fiber membrane (200) to be fixedly embedded in a predetermined position or arrangement within the housing (100), and also separates the inside and the outside of the housing (100), thereby preventing moist air introduced into the housing (100) from leaking out through a path other than the moist air outlet (150), and preventing dry air between the housing (100) and the cap (110) from entering the housing (100) through a path other than the hollow fiber membrane (200).

[0058] The inner potting material (310) may be spaced apart from the housing (100) with a gap (S) therebetween, and may be provided so as to move along the length direction of the hollow fiber membrane (200) together with the expansion and contraction of the first temperature-sensitive volume change member (400) provided between the outer potting material (320) and the inner potting material (310).

[0059] It is preferable that the size of the clearance (S) be provided within a range in which the hollow fiber membrane (200) does not undergo excessive deformation or damage due to sagging of the inner potting material (310) and the hollow fiber membrane (200) fixed by the inner potting material (310) according to the clearance (S).

[0060] Accordingly, the inner potting material (310) moves together with the expansion and contraction of the first temperature-sensitive volume change member (400), thereby moving the hollow fiber membrane (200) fixed by the inner potting material (310) in the longitudinal direction of the hollow fiber membrane (200), and the hollow fiber membrane (200) is tensioned or compressed in the longitudinal direction of the hollow fiber membrane (200) due to the movement of the inner potting material (310) provided at each end of the hollow fiber membrane (200), thereby controlling the stress applied to the hollow fiber membrane (200).

[0061] For example, as illustrated in FIG. 5, based on one side potting material (300), an outer potting material (320) connects and fixes the housing (100) and the potting material (300), and a first temperature-sensitive volume change member (400) is provided on the inside (+x direction in FIG. 5) of the fixed outer potting material (320), and again, an inner potting material (310) may be provided on the inside (+x direction in FIG. 5) of the first temperature-sensitive volume change member (400) with a gap (S) from the housing (100).

[0062] In some cases, an insert member may be further included to cover the outer surface of the inner potting material (310) so as to fill the gap (S) between the inner potting material (310) and the housing (100), and to have a smooth surface facing the housing (100) so as to enable sliding.

[0063] Next, in one embodiment of a membrane humidifier (10) for a fuel cell capable of controlling the length of a hollow fiber membrane according to the present invention, the first temperature-sensitive volume change member (400) may be provided with a material that contracts as the temperature increases and expands as the temperature decreases.

[0064] For example, the first temperature-sensitive volume change member (400) may be provided with a hydrogel that shrinks and expands depending on temperature or temperature and moisture, and specific examples thereof include poly(N-isopropyl acrylamide) (poly(N-isopropylacrylamide), poly(NIPAM)), poly(N-isopropyl acrylamide-co-allylamine) (poly(N-isopropyl acrylamide-co-allylamine), poly(NIPAM-co-AA)), poly(N-isopropyl acrylamide-co-2-(dimethylamino)ethyl methacrylate) (poly(N-isopropyl acrylamide-co-2-(dimethylamino)ethyl methacrylate), poly(NIPAM-co-DMAEMA)), poly(N-isopropyl acrylamide-co-2-(dimethylamino)ethyl acrylate), It may include at least one selected from the group consisting of poly(NIPAM-co-DMAEA)), poly(N-isopropyl acrylamide-co-acrylic acid), poly(NIPAM-co-AAc)), poly(N-isopropyl acrylamide-co-methacrylic acid), poly(NIPAM-co-MAAc)), poly(N,N-diethylacrylamide)), poly(N-vinylcaprolactam)), poly(ethylene glycol) and poly(ethylene glycol-b-propylene glycol-b-ethylene glycol)), but is not limited thereto.

[0065] Referring to FIG. 6, the function and effect of the membrane humidifier (10) for fuel cells capable of adjusting the length of the hollow fiber membrane according to the present invention according to the above configuration will be examined. First, FIG. 6a is a cross-sectional view and an enlarged view of a portion of the membrane humidifier in which the length of the hollow fiber membrane (200) increases according to the operation of the fuel cell.

[0066] During operation of the fuel cell, the hollow fiber membrane (200) is continuously pressured downward (in the -z direction in FIG. 6) by wet air flowing into the housing (100), and at the same time, it vibrates due to the strong flow pressure of dry air flowing inside the hollow fiber membrane (200), and this vibration applies stress to the hollow fiber membrane (200).

[0067] In particular, as the degree of sagging of the hollow fiber membrane (200) increases, the vibration amplitude increases and the stress intensity applied to the hollow fiber membrane (200) increases. In addition, as the inflow pressure of wet air and the flow pressure of dry air increase due to high-power operation of the fuel cell, the stress intensity applied to the hollow fiber membrane (200) increases and the possibility of damage to the hollow fiber membrane (200) increases.

[0068] Figure 6b shows the appearance when the temperature inside the housing (100) becomes relatively high due to high-power operation of the fuel cell.

[0069] Referring to FIG. 6b, as the temperature inside the housing (100) rises, the first temperature-sensitive volume change member (400) contracts, and accordingly, the inner potting material (310) moves toward the outer potting material (320) that is connected and fixed to the housing (100).

[0070] Accordingly, the inner potting material (310) at both ends of the hollow fiber membrane (200) moves toward each outer potting material (320), pulling the hollow fiber membrane (200) fixed to the inner potting material (310) at both ends, thereby maintaining the stretched hollow fiber membrane (200) taut again.

[0071] As the hollow fiber membrane (200) is maintained taut, vibration caused by flow is reduced, stress on the hollow fiber membrane (200) is alleviated, and ultimately the durability of the hollow fiber membrane (200) and the fuel cell humidifier is significantly improved.

[0072] Hereinafter, with reference to FIGS. 7 to 9, a membrane humidifier for a fuel cell capable of adjusting the clearance between hollow fiber membranes, which is one embodiment of the present invention, will be described.

[0073] In the description, configurations that are identical to or have a simple design change from the above-described embodiment and have the same action, function, and effect are indicated by adding the same drawing reference numerals or suffixes (e.g., 100, 100') to indicate that they can have the same action, function, and effect, and duplicate descriptions are omitted or kept to a minimum.

[0074] Fig. 7a is a perspective view of one embodiment of a membrane humidifier for a fuel cell capable of adjusting a clearance between hollow fiber membranes according to the present invention. Fig. 7b is a partially enlarged view of one embodiment of a membrane humidifier for a fuel cell capable of adjusting a clearance between hollow fiber membranes according to the present invention. Fig. 8 is a cross-sectional view showing the difference according to temperature with respect to a cross-section cut along the line II-II` in Fig. 7, wherein Fig. 8a is a cross-sectional view in a relatively low-temperature environment due to low-power operation of the fuel cell, and Fig. 8b is a cross-sectional view in a relatively high-temperature environment due to high-power operation of the fuel cell. Fig. 9 is a cross-sectional view showing a modified embodiment of a membrane humidifier for a fuel cell capable of adjusting a clearance between hollow fiber membranes according to the present invention.

[0075] Referring to FIG. 7a, one embodiment according to the present invention comprises a housing (100'), caps (110') positioned on both sides of the housing, a dry air inlet (120') provided in one cap (110') through which dry air is introduced, a dry air outlet (130') provided in the other cap (110') so that dry air introduced through the dry air inlet (120') is discharged through a hollow fiber membrane (200'), a wet air inlet (140') provided on the outer surface of the housing (100') through which wet air discharged from a stack (not shown) of a fuel cell is introduced into the housing (100'), a wet air outlet (150') through which wet air humidified inside the housing (100') is discharged, and a dry air outlet (150') located inside the housing (100') through which dry air introduced through the dry air inlet (120') flows inside and outside. The hollow fiber membrane (200') through which moist air introduced through the moist air inlet (140') flows and humidification is performed between moist air and dry air with the membrane between them, and a potting material (300') positioned at both ends of the hollow fiber membrane (200') to fix the ends of the hollow fiber membrane (200') may be included.

[0076] Referring to FIGS. 7b and 8, in one embodiment of a membrane humidifier (10') for a fuel cell capable of adjusting the clearance between hollow fiber membranes according to the present invention, a second temperature-sensitive volume change member (500) that expands and contracts depending on temperature can be inserted inside a potting material (300').

[0077] The second temperature-sensitive volume change member (500) can be inserted by dividing the potting material (300') into a plurality of pieces, so that each piece moves closer and farther away from each other around an axis parallel to the longitudinal direction of the hollow fiber membrane (200') according to the expansion and contraction of the second temperature-sensitive volume change member (500).

[0078] For example, as illustrated in FIG. 7b, the second temperature-sensitive volume change member (500) is inserted so as to divide the potting material (300') into four parts on a cross-sectional view taken along line II-II`, and one end of the second temperature-sensitive volume change member (500) may be inserted across the potting material (300') in the longitudinal direction of the hollow fiber membrane (200') (or the x-axis direction in FIG. 7b) so that the second end is exposed to the dry air between the cap (110') and the housing (100') and the other end is exposed to the wet air inside the housing (100'). Accordingly, each divided piece of the potting material (300') can move independently.

[0079] However, it is not limited thereto, and as shown in FIG. 9a, the potting material (300') may be divided into 8 or more equal parts, and as for the form of dividing the potting material (300'), the pieces of the divided potting material (300') may be divided with different sizes and shapes, as shown in FIG. 9b.

[0080] At this time, the second temperature-sensitive volume change member (500) may be provided with a material that expands as the temperature increases and contracts as the temperature decreases.

[0081] In addition, the second temperature-sensitive volume change member (500) may be provided with a material having a thermal expansion coefficient that is 30% or more greater than the thermal expansion coefficient of the potting material (300'). Preferably, the second temperature-sensitive volume change member (500) may be provided with a material having a thermal expansion coefficient that is 40% or more greater than the thermal expansion coefficient of the potting material (300'). More preferably, the second temperature-sensitive volume change member (500) may be provided with a material having a thermal expansion coefficient that is 50% or more greater than the thermal expansion coefficient of the potting material (300').

[0082] Accordingly, when the temperature inside the housing (100') rises due to high-power operation of the fuel cell, the second temperature-sensitive volume change member (500) expands, and accordingly, the clearance between each piece of the divided potting material (300') increases, and the clearance between the hollow fiber membranes (200') fixed to the potting material (300') also increases, so that smooth humidification can be achieved even inside the bundle of hollow fiber membranes (200').

[0083] On the other hand, when the temperature inside the housing (100') is relatively lowered due to low-power operation of the fuel cell, the second temperature-sensitive volume change member (500) relatively contracts, and accordingly, the play between each piece of the divided potting material (300') decreases. The play between the hollow fiber membranes (200') fixed to the potting material (300') also decreases, so that humidification is mainly performed around the hollow fiber membranes (200') located on the outside facing the housing (100'), and humidification up to the inside of the bundle of hollow fiber membranes (200') is reduced, thereby reducing the overall humidification efficiency. Accordingly, the amount of humidification is reduced in the low-power operation section of the fuel cell, thereby reducing the possibility of condensation generation.

[0084] In addition, when the second temperature-sensitive volume change member (500) is made of a material having a larger thermal expansion coefficient than that of the potting material (300'), in a situation where the internal temperature of the housing (100') rises due to high-power operation of the fuel cell, the second temperature-sensitive volume change member (500) expands more than the potting material (300') to effectively widen the gap between the divided potting materials (300'), and in a situation where the internal temperature of the housing (100') decreases due to low-power operation of the fuel cell, the second temperature-sensitive volume change member (500) contracts more than the potting material (300') to effectively narrow the gap between the divided potting materials (300'), thereby enabling sensitive humidification according to the output status of the fuel cell.

[0085] Next, referring again to FIGS. 7b and 8, in one embodiment of a membrane humidifier (10') for a fuel cell capable of adjusting the clearance between hollow fiber membranes (200') according to the present invention, a third temperature-sensitive volume change member (600) that expands and contracts depending on temperature can be inserted between a potting material (300') and a housing (100').

[0086] For example, as shown in FIGS. 7b and 8, each piece of the four-part potting material (300') may be provided with a third temperature-sensitive volume change member (600) surrounding the surface facing the housing (100').

[0087] The third temperature-sensitive volume change member (600) is provided between the potting material (300') and the housing (100') to provide a space that can be moved apart between the divided pieces of the potting material (300') when the second temperature-sensitive volume change member (500) expands.

[0088] To this end, in one embodiment of a membrane humidifier (10') for a fuel cell capable of adjusting the clearance between hollow fiber membranes (200') according to the present invention, the third temperature-sensitive volume change member (600) may be provided with a material that contracts as the temperature increases and expands as the temperature decreases.

[0089] For example, the third temperature-sensitive volume change member (600) may be provided with a hydrogel that shrinks as the temperature increases and expands as the temperature decreases, and specifically, poly(N-isopropyl acrylamide) (poly(N-isopropylacrylamide), poly(NIPAM)), poly(N-isopropyl acrylamide-co-allylamine) (poly(N-isopropyl acrylamide-co-allylamine), poly(NIPAM-co-AA)), poly(N-isopropyl acrylamide-co-2-(dimethylamino)ethyl methacrylate) (poly(N-isopropyl acrylamide-co-2-(dimethylamino)ethyl methacrylate), poly(NIPAM-co-DMAEMA)), poly(N-isopropyl acrylamide-co-2-(dimethylamino)ethyl acrylate), It can be provided with a material including at least one selected from the group consisting of poly(NIPAM-co-DMAEA)), poly(N-isopropyl acrylamide-co-acrylic acid), poly(NIPAM-co-AAc)), poly(N-isopropyl acrylamide-co-methacrylic acid), poly(NIPAM-co-MAAc)), poly(N,N-diethylacrylamide)), poly(N-vinylcaprolactam)), poly(ethylene glycol) and poly(ethylene glycol-b-propylene glycol-b-ethylene glycol)), but is not limited thereto.

[0090] Referring again to FIGS. 8 and 9, the function, operation, and effect of the membrane humidifier (10') for a fuel cell capable of adjusting the clearance between the hollow fiber membranes according to the present invention according to the above configuration will be examined. The second temperature-sensitive volume-changing member (500, 500', 500'') is inserted into the potting material (300') to divide the potting material (300') into independent pieces, and the second temperature-sensitive volume-changing member (500, 500', 500'') is made of a material that expands as the temperature increases and contracts as the temperature decreases, so that in a relatively high-temperature environment (FIGS. 8b, 9b, and 9d) due to high-power operation of the fuel cell, the pieces of the divided potting material (300') move away from each other, and in a relatively low-temperature environment (FIGS. 8a, 9a, and 9c) due to low-power operation of the fuel cell, the pieces of the divided potting material (300') move closer to each other.

[0091] In addition, a third temperature-sensitive volume change member (600, 600', 600'') is inserted between the housing (100') and the potting material (300'), and the third temperature-sensitive volume change member (600, 600', 600'') is made of a material that contracts as the temperature increases and expands as the temperature decreases, thereby providing a space in which pieces of the potting material (300') can move apart from each other in a high-power operation section of the fuel cell, and maintaining a seal between the potting material (300') and the housing (100') in a low-power operation section of the fuel cell, thereby preventing wet air inside the housing (100') and dry air inside the cap (110') from mixing.

[0092] According to changes in the second temperature-sensitive volume change member (500, 500', 500''), the third temperature-sensitive volume change member (600, 600', 600'') and the potting material (300'), the clearance between the hollow fiber membranes (200') is adjusted according to the output state of the fuel cell.

[0093] Specifically, since the clearance between the hollow fiber membranes (200') increases in the high-power operation section of the fuel cell, the humidification efficiency is significantly improved through smooth humidification up to the inside of the hollow fiber membrane (200') bundle, and since the clearance between the hollow fiber membranes (200') decreases in the low-power operation section of the fuel cell, the humidification efficiency is relatively reduced, and accordingly, it can be easily expected that the problem of over-humidification or condensation generation, which is mentioned as a problem in the low-power operation section, is significantly improved.

[0094] Accordingly, one embodiment of a membrane humidifier (10') for a fuel cell capable of adjusting the clearance between hollow fiber membranes (200') disclosed in the present invention has an excellent effect of actively controlling the amount of humidification and preventing over-humidification, thereby improving the durability of the membrane humidifier for a fuel cell.

[0095] The foregoing description of the present invention is for illustrative purposes only, and those skilled in the art will readily appreciate that modifications to other specific forms can be made without altering the technical spirit or essential characteristics of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting.

[0096] For example, although the present invention has been described with reference to an embodiment illustrated in the drawings, this is merely exemplary, and those skilled in the art will understand that various modifications and variations of the embodiments are possible from this.

[0097] Therefore, the true technical protection scope of the present invention is indicated by the technical idea of ​​the patent claims described below, and all changes or modified forms derived from the image and scope of the patent claims and their equivalent concepts should be interpreted as being included in the scope of the present invention.

Claims

1. In a humidifier for fuel cells, housing; A hollow fiber membrane located inside the housing, through which dry air flows inside and moist air flows outside; and A potting material positioned at both ends of the hollow fiber membrane and fixing the ends of the hollow fiber membrane; A fuel cell membrane humidifier with a hollow fiber membrane length controllable, characterized in that the potting material has a first temperature-sensitive volume-changing member inserted therein that expands and contracts according to temperature, and is divided into an inner potting material located inside the housing and an outer potting material located outside the housing and spaced apart from the inner potting material based on the first temperature-sensitive volume-changing member.

2. In paragraph 1, A membrane humidifier for a fuel cell with a hollow fiber membrane length adjustment capability, characterized in that the inner potting material is spaced apart from the housing with a gap therebetween and can move in the longitudinal direction of the hollow fiber membrane according to expansion and contraction of the first temperature-sensitive volume change member.

3. In paragraph 1, A membrane humidifier for a fuel cell with an adjustable hollow fiber membrane length, characterized in that the outer potting material is fixed to the housing.

4. In paragraph 1. A membrane humidifier for a fuel cell with a hollow fiber membrane length controllable, characterized in that the first temperature-sensitive volume change member shrinks as the temperature increases and expands as the temperature decreases.

5. In paragraph 1, The first temperature-sensitive volume change member is poly(N-isopropyl acrylamide) (poly(N-isopropylacrylamide), poly(NIPAM)), poly(N-isopropyl acrylamide-co-allylamine) (poly(N-isopropyl acrylamide-co-allylamine), poly(NIPAM-co-AA)), poly(N-isopropyl acrylamide-co-2-(dimethylamino)ethyl methacrylate) (poly(N-isopropyl acrylamide-co-DMAEMA)), poly(N-isopropyl acrylamide-co-2-(dimethylamino)ethyl acrylate) (poly(N-isopropyl acrylamide-co-DMAEA)), poly(N-isopropyl acrylamide-co-acrylic acid) (poly(N-isopropyl A membrane humidifier for a fuel cell with a hollow fiber membrane length controllable, characterized in that it comprises at least one selected from the group consisting of poly(N-isopropyl acrylamide-co-acrylic acid), poly(NIPAM-co-AAc), poly(N-isopropyl acrylamide-co-methacrylic acid), poly(NIPAM-co-MAAc), poly(N,N-diethylacrylamide), poly(N-vinylcaprolactam), poly(ethylene glycol), and poly(ethylene glycol-b-propylene glycol-b-ethylene glycol).

6. In a humidifier for fuel cells, housing; A hollow membrane located inside the housing, through which a first fluid flows inside and a second fluid flows outside; and A potting material positioned at both ends of the hollow fiber membrane and fixing the ends of the hollow fiber membrane; A membrane humidifier for a fuel cell capable of adjusting the clearance between hollow fiber membranes, characterized in that the potting material is divided into a plurality of pieces by inserting a second temperature-sensitive volume-changing member that expands and contracts according to temperature therein, and each of the divided pieces moves closer and farther away from each other around an axis parallel to the longitudinal direction of the hollow fiber membrane according to the expansion and contraction of the temperature-sensitive volume-changing member.

7. In paragraph 6, A membrane humidifier for a fuel cell capable of controlling the clearance between hollow fiber membranes, characterized in that a third temperature-sensitive volume change member that surrounds the potting material and expands and contracts depending on temperature is inserted between the potting material and the housing.

8. In paragraph 6, A membrane humidifier for a fuel cell capable of controlling the clearance between hollow fiber membranes, characterized in that the second temperature-sensitive volume change member expands as the temperature increases and contracts as the temperature decreases.

9. In paragraph 6, A membrane humidifier for a fuel cell capable of controlling a clearance between hollow fiber membranes, characterized in that the second temperature-sensitive volume change member has a thermal expansion coefficient that is 50% or more greater than the thermal expansion coefficient of the potting material.

10. In paragraph 7, A membrane humidifier for a fuel cell capable of controlling the clearance between hollow fiber membranes, characterized in that the third temperature-sensitive volume change member shrinks as the temperature increases and expands as the temperature decreases.

11. In paragraph 7, The third temperature-sensitive volume change member is poly(N-isopropyl acrylamide) (poly(N-isopropylacrylamide), poly(NIPAM)), poly(N-isopropyl acrylamide-co-allylamine) (poly(N-isopropyl acrylamide-co-allylamine), poly(NIPAM-co-AA)), poly(N-isopropyl acrylamide-co-2-(dimethylamino)ethyl methacrylate) (poly(N-isopropyl acrylamide-co-DMAEMA)), poly(N-isopropyl acrylamide-co-2-(dimethylamino)ethyl acrylate) (poly(N-isopropyl acrylamide-co-DMAEA)), poly(N-isopropyl acrylamide-co-acrylic acid) (poly(N-isopropyl A membrane humidifier for a fuel cell capable of controlling the clearance between hollow fiber membranes, characterized in that it comprises at least one selected from the group consisting of poly(N-isopropyl acrylamide-co-acrylic acid), poly(NIPAM-co-AAc), poly(N-isopropyl acrylamide-co-methacrylic acid), poly(NIPAM-co-MAAc), poly(N,N-diethylacrylamide), poly(N-vinylcaprolactam), poly(ethylene glycol), and poly(ethylene glycol-b-propylene glycol-b-ethylene glycol).

Images