Patent Description:
A fuel cell is a power generation cell that combines hydrogen and oxygen to generate electricity. The fuel cell has advantages in that it is possible to continuously generate electricity as long as hydrogen and oxygen are supplied, unlike a general chemical cell, such as a dry cell or a storage cell, and in that there is no heat loss, whereby efficiency of the fuel cell is about twice as high as efficiency of an internal combustion engine.

In addition, the fuel cell directly converts chemical energy generated by combination of hydrogen and oxygen into electrical energy, whereby the amount of contaminants that are discharged is small. Consequently, the fuel cell has advantages in that the fuel cell is environmentally friendly and in that a concern about depletion of resources due to an increase in energy consumption can be reduced. <CIT> relates to a membrane humidifier having a sealing member interposed between a housing and a potting portion fixing an end portion of a hollow fiber membrane bundle to the housing. <CIT> relates to a gas humidifier and its method, and is particularly suitable for solving the problems of industrial humidification such as fuel cell humidification and life production humidification such as room humidification and seedling preservation freshness humidification. <CIT> relates to capillary dialyzers for blood purification. <CIT> relates to a filter with membranes of hollow fibres, wherein the hollow fibres are arranged as a bundle in a tubular housing.

Based on the kind of an electrolyte that is used, such a fuel cell may generally be classified into a polymer electrolyte membrane fuel cell (PEMFC), a phosphoric acid fuel cell (PAFC), a molten carbonate fuel cell (MCFC), a solid oxide fuel cell (SOFC), or an alkaline fuel cell (AFC).

These fuel cells are operated fundamentally by the same principle, but are different from each other in terms of the kind of fuel that is used, operating temperature, catalyst, and electrolyte. Among these fuel cells, the polymer electrolyte membrane fuel cell (PEMFC) is known as being the most favorable to a transportation system as well as small-scale stationary power generation equipment, since the polymer electrolyte membrane fuel cell is operated at a lower temperature than the other fuel cells and the output density of the polymer electrolyte membrane fuel cell is high, whereby it is possible to miniaturize the polymer electrolyte membrane fuel cell.

One of the most important factors in improving the performance of the polymer electrolyte membrane fuel cell (PEMFC) is to supply a predetermined amount or more of moisture to a polymer electrolyte membrane or a proton exchange membrane (PEM) of a membrane electrode assembly (MEA) in order to retain moisture content. The reason for this is that, if the polymer electrolyte membrane or the proton exchange membrane is dried, power generation efficiency is abruptly reduced.

<NUM>) A bubbler humidification method of filling a pressure-resistant container with water and allowing a target gas to pass through a diffuser in order to supply moisture, <NUM>) a direct injection method of calculating the amount of moisture to be supplied that is necessary for fuel cell reaction and directly supplying moisture to a gas stream pipe through a solenoid valve, and <NUM>) a membrane humidification method of supplying moisture to a gas fluid bed using a polymer separation membrane are used as methods of humidifying the polymer electrolyte membrane or the proton exchange membrane.

Among these methods, the membrane humidification method, which provides water vapor to gas (i.e. air or fuel gas) that is supplied to the polymer electrolyte membrane or the proton exchange membrane using a membrane configured to selectively transmit only water vapor included in off-gas in order to humidify the polymer electrolyte membrane or the proton exchange membrane, is advantageous in that it is possible to reduce the weight and size of a humidifier.

When a module is formed, a hollow fiber membrane having large transmission area per unit volume is suitable for a permselective membrane used in the membrane humidification method. That is, when a humidifier is manufactured using a hollow fiber membrane, high integration of the hollow fiber membrane having large contact surface area is possible, whereby it is possible to sufficiently humidify the polymer electrolyte membrane or the proton exchange membrane even at a small capacity, it is possible to use a low-priced material, and it is possible to collect moisture and heat included in off-gas discharged from the fuel cell at a high temperature and to reuse the collected moisture and heat through the humidifier.

As illustrated in <FIG>, a conventional membrane humidification type humidifier <NUM> includes a humidifying module <NUM> in which moisture exchange is performed between gas supplied from the outside and off-gas discharged from a fuel cell stack (not shown), and caps <NUM> coupled respectively to opposite ends of the humidifying module <NUM>.

One of the caps <NUM> transmits gas supplied from the outside to the humidifying module <NUM>, and the other cap transmits gas humidified by the humidifying module <NUM> to the fuel cell stack.

The humidifying module <NUM> includes a mid-case <NUM> having an off-gas inlet <NUM>10a and an off-gas outlet <NUM>10b and a plurality of hollow fiber membranes <NUM> disposed in the mid-case <NUM>. Opposite ends of a bundle of hollow fiber membranes <NUM> are potted in fixing layers <NUM>. In general, each of the fixing layers <NUM> is formed by hardening a liquid polymer, such as liquid polyurethane resin, using a casting method (e.g. dip casting, which is also called dip potting, or centrifugal casting, which is also called centrifugal potting).

Gas supplied from the outside flows along hollow parts of the hollow fiber membranes <NUM>. Off-gas introduced into the mid-case <NUM> through the off-gas inlet 1110a comes into contact with the outer surfaces of the hollow fiber membranes <NUM>, and is discharged from the mid-case <NUM> through the off-gas outlet 1110b. When the off-gas comes into contact with the outer surfaces of the hollow fiber membranes <NUM>, moisture contained in the off-gas is transmitted through the hollow fiber membranes <NUM> to humidify gas flowing along the hollow parts of the hollow fiber membranes <NUM>.

Inner spaces of the caps <NUM> must fluidly communicate with only the hollow parts of the hollow fiber membranes <NUM> in a state of being completely isolated from an inner space of the mid-case <NUM>. If not, gas leakage due to pressure difference occurs, whereby power generation efficiency of a fuel cell is reduced.

In general, as illustrated in <FIG>, the fixing layers <NUM> and resin layers <NUM> provided between the fixing layers <NUM> and the mid-case <NUM> isolate the inner spaces of the caps <NUM> from the inner space of the mid-case <NUM>. Similarly to the fixing layers <NUM>, each of the resin layers <NUM> is generally formed by hardening a liquid polymer, such as liquid polyurethane resin, using a casting method (dip casting or centrifugal casting).

However, (i) the resin layer <NUM> is alternately expanded and contracted as a result of repeated operation and stop of the fuel cell, whereby the resin layer <NUM> is separated from the mid-case <NUM> due to a difference in coefficient of thermal expansion between the mid-case <NUM> and the resin layer <NUM>, and therefore a gap is generated therebetween, or (ii) there is a high probability of a gap being generated between the resin layer <NUM> and the mid-case <NUM> due to vibration and/or impact. The gap between the resin layer <NUM> and the mid-case <NUM> causes gas leakage, thereby reducing power generation efficiency of the fuel cell.

In order to prevent gas leakage due to generation of the gap between the resin layer <NUM> and the mid-case <NUM>, <CIT> discloses a method of applying a sealant (liquid sealing member) to a step formed on the side surface of the resin layer <NUM> and a groove formed in the inner surface of the mid-case <NUM>, inserting a packing member (solid sealing member) into the groove, and hardening the sealant.

However, the above method has problems of low productivity and high manufacturing cost in that (i) the sealant must be applied so as to accurately match with the groove, whereby workability is low, (ii) a considerably long time of <NUM> hours or more is required to harden the sealant, and (iii) a separate space for storing the humidifying module <NUM> is required until the sealant is hardened.

Therefore, the present disclosure relates to a humidifier for a fuel cell capable of preventing problems caused by limitations and shortcomings of the related art described above and a method of manufacturing the same.

It is an object of the present disclosure to provide a humidifier for a fuel cell capable of certainly preventing gas leakage due to repeated operation and stop of a fuel cell and being manufactured with relatively low manufacturing cost and high productivity.

It is another object of the present disclosure to provide a method of manufacturing a humidifier for a fuel cell capable of certainly preventing gas leakage due to repeated operation and stop of a fuel cell with relatively low manufacturing cost and high productivity.

In addition to the above objects, other features and advantages of the present disclosure will be described hereinafter, or will be clearly understood by those skilled in the art to which the present disclosure pertains from the following description thereof.

In accordance with an aspect of the present disclosure, there is provided a humidifier for a fuel cell, the humidifier including a humidifying module configured to humidify gas supplied from outside using moisture in off-gas discharged from a fuel cell stack and caps coupled respectively to opposite ends of the humidifying module, wherein the humidifying module includes a mid-case open at opposite ends thereof, the mid-case having a step at the inner circumferential surface thereof, a plurality of hollow fiber membranes disposed in the mid-case, a fixing layer in which ends of the hollow fiber membranes are potted, a bracket supported by the step of the mid-case, the bracket being in contact with the fixing layer, and a packing member having a groove into which the end of the mid-case is inserted, the packing member being in contact with the bracket.

The humidifying module may further include a primer layer disposed between the bracket and the fixing layer or between the bracket and the packing member, and the bracket may be disposed in indirect contact with the fixing member or the packing member via the primer layer.

The primer layer may include a rubber adhesive component, an acrylic adhesive component, a polyurethane adhesive component, an epoxy adhesive component, a silicone adhesive component, a polyamide-based adhesive component, a polyimide-based adhesive component, or a mixture of two or more thereof.

Each of the bracket and the packing member may have a simple closed curve shape corresponding to the shape of a traverse section of the mid-case.

The bracket may have higher hardness than the packing member.

For example, the bracket may have a hardness of <NUM> to <NUM> Shore A, and the packing member may have a hardness of <NUM> to <NUM> Shore A.

The packing member may include soft rubber, and the bracket may include metal, rigid plastic, or hard rubber.

The packing member may include silicone rubber or urethane rubber, and the bracket may include polypropylene (PP), polyethylene terephthalate (PET), polystyrene (PS), polycarbonate (PC), or acrylic resin.

The packing member is in contact also with the fixing layer.

The fixing layer may include a first fixing layer in which the ends of the hollow fiber membranes are potted, and a second fixing layer in contact with the bracket, the second fixing layer surrounding the first fixing layer.

The first fixing layer and the second fixing layer may be formed of the same material.

Both the first fixing layer and the second fixing layer may include polyurethane (PU) resin.

The humidifying module may further include an inner case disposed in the mid-case, the inner case being open at opposite ends thereof, and the hollow fiber membranes may be disposed in the inner case.

The end of the inner case may be potted in the first fixing layer.

The hollow fiber membranes may include a first group of hollow fiber membranes and a second group of hollow fiber membranes, the humidifying module may further include a first inner case in which the first group of hollow fiber membranes is disposed and a second inner case in which the second group of hollow fiber membranes is disposed, and the fixing layer may include a first fixing layer in which ends of the first group of hollow fiber membranes are potted, a second fixing layer in which ends of the second group of hollow fiber membranes are potted, and a third fixing layer in contact with the bracket, the third fixing layer surrounding the first and second fixing layers.

An end of the first inner case may be potted in the first fixing layer, and an end of the second inner case is potted in the second fixing layer.

In accordance with another aspect of the present disclosure, there is provided a method of manufacturing a humidifier for a fuel cell, the method including preparing a hollow fiber membrane cartridge having a first fixing layer in which ends of a plurality of hollow fiber membranes are potted, inserting the hollow fiber membrane cartridge into a mid-case open at opposite ends thereof, the mid-case having a step at the inner circumferential surface thereof, mounting a bracket on the step of the mid-case, mounting a packing member having a groove corresponding to the end of the mid-case on the end of the mid-case such that the end of the mid-case is inserted into the groove and a portion of the packing member comes into contact with the bracket, forming a second fixing layer configured to fill a gap between the mid-case and an end of the hollow fiber membrane cartridge, a gap between the bracket and the end of the hollow fiber membrane cartridge, and a gap between the packing member and the end of the hollow fiber membrane cartridge, simultaneously cutting the first fixing layer, the second fixing layer, and the hollow fiber membranes to open the ends of the hollow fiber membranes, and fastening a cap to the mid-case such that the packing member is compressed by the cap.

The preparing the hollow fiber membrane cartridge may include inserting at least a portion of each of the hollow fiber membranes into an inner case and performing a dip casting process or a centrifugal casting process to form the first fixing layer.

An end of the inner case may also be potted in the first fixing layer together with the ends of the hollow fiber membranes when the dip casting process or the centrifugal casting process is performed.

The bracket may have higher hardness than the packing member such that the packing member is compressed when the cap is fastened to the mid-case.

The general description of the present disclosure given above is provided merely to illustrate or describe the present disclosure, and does not limit the scope of rights of the present disclosure.

According to the present disclosure, workability is improved and manufacturing time is reduced, whereby it is possible to remarkably improve productivity thereof, since a sealant application process and a sealant hardening process, which are required in the conventional art, are omitted.

In addition, a separate space for storing a half-finished product for the sealant hardening process is not required, whereby it is possible to reduce production cost of a humidifier.

The accompanying drawings, which are included to assist in understanding of the present disclosure and are incorporated in and constitute a part of the present specification, illustrate embodiments of the present disclosure and serve to explain the principle of the present disclosure together with the detailed description of the present disclosure.

However, the following embodiments are illustratively provided merely for clear understanding of the present disclosure and do not limit the scope of the present disclosure.

<FIG> and <FIG> are sectional views showing an end of a humidifier or a half-finished product, and the other end thereof has a substantially identical (or symmetrical) section.

As illustrated in <FIG>, a humidifier <NUM> for a fuel cell according to the present disclosure includes a humidifying module <NUM> configured to humidify gas supplied from the outside using moisture in off-gas discharged from a fuel cell stack. Opposite ends of the humidifying module <NUM> are coupled to caps <NUM>, respectively.

One of the caps <NUM> receives gas from the outside through a port <NUM> and transmits the gas to the humidifying module <NUM>, and the other cap transmits gas humidified by the humidifying module <NUM> to the fuel cell stack through a port <NUM>. Each of the caps <NUM> may be formed of rigid plastic (e.g. polycarbonate, polyamide (PA), or polyphthalamide (PPA)) or metal, and may have a simple closed curve-shaped (e.g. circular or polygonal) traverse section.

The humidifying module <NUM> according to the embodiment of the present disclosure, in which moisture exchange is performed between gas supplied from the outside and off-gas supplied from the fuel cell stack, includes a mid-case <NUM> open at opposite ends thereof, the mid-case having a step <NUM> formed at the inner circumferential surface thereof, a plurality of hollow fiber membranes <NUM> disposed in the mid-case <NUM>, a fixing layer <NUM> in which ends of the hollow fiber membranes <NUM> are potted, a bracket <NUM> supported by the step <NUM> of the mid-case <NUM>, the bracket being in contact with the fixing layer <NUM>, and a packing member <NUM> having a groove into which the end of the mid-case <NUM> is inserted, the packing member being in contact with the bracket <NUM>.

The mid-case <NUM> has ports <NUM> for off-gas introduction/discharge (only one is shown in <FIG>). The mid-case <NUM> may be formed of rigid plastic (e.g. polycarbonate, polyamide (PA), or polyphthalamide (PPA)) or metal, and may have a simple closed curve-shaped (e.g. circular or polygonal) traverse section. According to the embodiment of the present disclosure, the mid-case <NUM> may have the same traverse section as the cap <NUM>.

Each of the hollow fiber membranes <NUM> may include a polymer membrane formed of polysulfone resin, polyethersulfone resin, sulfonated polysulfone resin, polyvinylidene fluoride (PVDF) resin, polyacrylonitrile (PAN) resin, polyimide resin, polyamide imide resin, polyester imide resin, or a mixture of two or more thereof.

Gas supplied from the outside through one cap <NUM> is humidified while flowing along hollow parts of the hollow fiber membranes <NUM>, and is transmitted to the fuel cell stack through the other cap <NUM>.

Off-gas introduced into the mid-case <NUM> comes into contact with the outer surfaces of the hollow fiber membranes <NUM>, and is discharged from the mid-case <NUM>. When the off-gas comes into contact with the outer surfaces of the hollow fiber membranes <NUM>, moisture contained in the off-gas is transmitted through the hollow fiber membranes <NUM> to humidify gas flowing along the hollow parts of the hollow fiber membranes <NUM>.

The fixing layer <NUM> which may be formed of hard or soft polyurethane resin must isolate the inner space of the cap <NUM> from the inner space of the mid-case <NUM> such that the cap <NUM> can fluidly communicate only with the hollow fiber membranes <NUM>.

As previously described, however, (i) the fixing layer <NUM> is alternately expanded and contracted as a result of repeated operation and stop of a fuel cell, whereby the fixing layer <NUM> is separated from the mid-case <NUM> due to a difference in coefficient of thermal expansion between the mid-case <NUM> and the fixing layer <NUM>, and therefore a gap is generated therebetween, or (ii) there is a high probability of a gap being generated between the fixing layer <NUM> and the mid-case <NUM> due to vibration and/or impact. The gap between the fixing layer <NUM> and the mid-case <NUM> causes gas leakage, thereby reducing power generation efficiency of the fuel cell.

Gas leakage that may be caused by generation of the gap between the fixing layer <NUM> and the mid-case <NUM> includes (i) external leakage by which off-gas in the inner space of the mid-case <NUM> sequentially passes through the gap between the fixing layer <NUM> and the mid-case <NUM> and the gap between the cap <NUM> and the mid-case <NUM> and is then discharged out of the humidifier <NUM> and (ii) internal leakage by which off-gas in the inner space of the mid-case <NUM> sequentially passes through the gap between the fixing layer <NUM> and the mid-case <NUM> and the gap between the fixing layer <NUM> and the cap <NUM> and is then introduced into the inner space of the cap <NUM>.

In order to prevent gas leakage due to generation of the gap between the fixing layer <NUM> and the mid-case <NUM>, the humidifying module <NUM> of the humidifier <NUM> for a fuel cell according to the present disclosure further includes the bracket <NUM> and the packing member <NUM>.

As illustrated in <FIG>, the bracket <NUM>, which is supported by the step <NUM> of the mid-case <NUM>, may have a simple closed curve shape corresponding to the shape of the traverse section of the mid-case <NUM>.

Similarly, as illustrated in <FIG>, the packing member <NUM> having the groove G into which the end of the mid-case <NUM> is inserted may also have a simple closed curve shape corresponding to the shape of the traverse section of the mid-case <NUM>.

According to the embodiment of the present disclosure, the bracket <NUM> has higher hardness than the packing member <NUM> and is strongly adhered to the fixing layer <NUM>.

For example, the packing member <NUM> may have a relatively low hardness of <NUM> to <NUM> Shore A, more preferably <NUM> to <NUM> Shore A, so as to be compressed by pressure applied when the cap <NUM> is fastened to the mid-case <NUM> through a bolt <NUM> and a nut <NUM>, and the bracket <NUM> may have a hardness of <NUM> to <NUM> Shore A, more preferably <NUM> to <NUM> Shore A, which is higher than the hardness of the packing member <NUM>.

According to the embodiment of the present disclosure, the packing member <NUM> may include soft rubber (e.g. silicone rubber or urethane rubber), and the bracket <NUM> may include metal, rigid plastic (e.g. polypropylene (PP), polyethylene terephthalate (PET), polystyrene (PS), polycarbonate (PC), or acrylic resin), or hard rubber.

When the cap <NUM> is fastened to the mid-case <NUM> through the bolt <NUM> and the nut <NUM>, the portion of the packing member <NUM> disposed between the cap <NUM> and the mid-case <NUM> (particularly, the portion of the packing member <NUM> corresponding to the groove into which the end of the mid-case <NUM> is inserted) is compressed by pressure applied by the cap <NUM> and the mid-case <NUM>, whereby movement of gas through the interface between the packing member <NUM> and the mid-case <NUM> (i.e. external leakage) can be prevented, and therefore tight external sealing may be guaranteed.

In addition, since the bracket <NUM> is supported by the step <NUM> of the mid-case <NUM> and has relatively high hardness, the bracket <NUM> may effectively apply pressure to the packing member <NUM> together with the cap <NUM> when the cap <NUM> is fastened to the mid-case <NUM> through the bolt <NUM> and the nut <NUM>. As a result, the portion of the packing member <NUM> disposed between the cap <NUM> and the bracket <NUM> (i.e. located in the mid-case <NUM>) is sufficiently compressed, whereby movement of gas through the interface between the packing member <NUM> and the bracket <NUM> (i.e. internal leakage) can be prevented, and therefore excellent internal sealing may be guaranteed.

In addition, since the bracket <NUM> according to the embodiment of the present disclosure has excellent adhesive force with respect to the fixing layer <NUM>, movement of gas through the interface between the bracket <NUM> and the fixing layer <NUM> (i.e. internal leakage) can be prevented, and therefore stronger internal sealing may be provided.

Optionally, as shown in <FIG>, the humidifying module <NUM> according to the embodiment of the present disclosure may further include a primer layer <NUM> formed on at least a portion of the surface of the bracket <NUM>.

<FIG> illustrates the humidifier <NUM> having the primer layer <NUM> formed on the entire surface of the bracket <NUM>; however, the present disclosure is not limited thereto. The primer layer <NUM> may be disposed (i) between the bracket <NUM> and the mid-case <NUM>, (ii) between the bracket <NUM> and the fixing layer <NUM>, and/or (iii) between the bracket <NUM> and the packing member <NUM>.

When the bracket <NUM> is in indirect contact with the mid-case <NUM> and/or the packing member <NUM> via the primer layer <NUM>, the adhesive force therebetween is increased, whereby movement of gas through the interface therebetween (i.e. internal leakage and external leakage) can be prevented, and therefore stronger internal and external sealing can be provided.

Similarly, when the bracket <NUM> is in indirect contact with the fixing layer <NUM> via the primer layer <NUM>, the adhesive force therebetween is further increased, whereby an internal sealing effect can be maximized.

The primer layer <NUM> according to the present disclosure adopted to improve the sealing effect through an increase in adhesive force may include a rubber adhesive component, an acrylic adhesive component, a polyurethane adhesive component, an epoxy adhesive component, a silicone adhesive component, a polyamide-based adhesive component, a polyimide-based adhesive component, or a mixture of two or more thereof.

For the rubber adhesive component, natural rubber (NR) and/or synthetic rubber may be used. The synthetic rubber may be SBR, NBR, CR, BR, IIR, and/or EPDM.

For the acrylic adhesive component, acrylic emulsion, anaerobic acrylic resin, and/or acrylic resin-based adhesive tape may be used.

For the polyurethane adhesive component, solvent-type polyurethane, polyurethane hot melt, or urethane emulsion may be used.

For the polyamide-based adhesive component, polyamide hot melt may be used.

As illustrated in <FIG> and <FIG>, the cap <NUM> according to the embodiment of the present disclosure may have a protrusion <NUM> formed at a position corresponding to the end of the mid-case <NUM> inserted into the groove G of the packing member <NUM>. The protrusion <NUM> more effectively compresses the packing member <NUM> together with the end of the mid-case <NUM>, whereby tighter external sealing is achieved.

As illustrated in <FIG> and <FIG>, the packing member <NUM> according to the embodiment of the present disclosure may be in contact with the fixing layer <NUM>. Liquid resin (e.g. liquid polyurethane resin) used to form the fixing layer <NUM> is hardened in a state of being in contact with the packing member <NUM>, whereby adhesive strength between the packing member <NUM> and the fixing layer <NUM> may be increased and thus internal sealing may be improved.

According to the embodiment of the present disclosure, as illustrated in <FIG> and <FIG>, the fixing layer <NUM> may include a first fixing layer <NUM>-<NUM> in which the ends of the hollow fiber membranes <NUM> are potted, and a second fixing layer <NUM>-<NUM> in contact with the bracket <NUM>, the a second fixing layer <NUM>-<NUM> surrounding the first fixing layer <NUM>-<NUM>.

Each of the first fixing layer <NUM>-<NUM> and the second fixing layer <NUM>-<NUM> may be formed by hardening liquid resin, such as liquid polyurethane resin, using a dip casting method or a centrifugal casting method. Although the first fixing layer <NUM>-<NUM> and the second fixing layer <NUM>-<NUM> may be formed of different materials, it may be preferable for the first fixing layer and the second fixing layer to be formed of the same material (e.g. polyurethane resin) in terms of adhesive strength therebetween.

As illustrated in <FIG> and <FIG>, the humidifying module <NUM> may further include an inner case <NUM> disposed in the mid-case <NUM>, the inner case being open at opposite ends thereof. In this case, the hollow fiber membranes <NUM> are disposed in the inner case <NUM>. The first fixing layer <NUM>-<NUM> in which ends of the hollow fiber membranes <NUM> are potted closes a corresponding one of the open ends of the inner case <NUM>.

According to the embodiment of the present disclosure, the inner case <NUM> has a plurality of holes H provided at positions corresponding to the ports <NUM> for off-gas introduction/discharge (only one is shown in <FIG>). Off-gas introduced into the mid-case <NUM> through the first port <NUM> passes through the first holes H and then absorbs moisture while flowing along the outer surfaces of the hollow fiber membranes <NUM>. Subsequently, the off-gas exits the inner case <NUM> through the second holes H on the opposite side and is then discharged from the mid-case <NUM> through the second port <NUM>.

The hollow fiber membranes <NUM>, the first fixing layer <NUM>-<NUM>, and the inner case <NUM> constitute a hollow fiber membrane cartridge <NUM>.

As illustrated in <FIG> and <FIG>, an end of the inner case <NUM> is potted in the first fixing layer <NUM>-<NUM>, whereby relative positions of the hollow fiber membranes <NUM> and the inner case <NUM> may be uniformly maintained.

Hereinafter, a humidifier <NUM> for a fuel cell according to a second embodiment of the present disclosure will be described with reference to <FIG>.

As illustrated in <FIG>, the humidifier <NUM> for a fuel cell according to the second embodiment of the present disclosure is substantially identical to the first embodiment described above except that the humidifier includes two hollow fiber membrane cartridges 2120a and 2120b.

That is, according to the second embodiment of the present disclosure, the hollow fiber membranes include a first group of hollow fiber membranes 2121a and a second group of hollow fiber membranes 2121b, the humidifying module <NUM> includes a first inner case 2123a in which the first group of hollow fiber membranes 2121a is disposed and a second inner case 2123b in which the second group of hollow fiber membranes 2121b is disposed, and the fixing layer <NUM> includes a first fixing layer <NUM>-1a in which ends of the first group of hollow fiber membranes 2121a are potted, a second fixing layer <NUM>-1b in which ends of the second group of hollow fiber membranes 2121b are potted, and a third fixing layer <NUM>-<NUM> in contact with the bracket <NUM>, the third fixing layer <NUM>-<NUM> surrounding the first and second fixing layers <NUM>-1a and <NUM>-1b.

The first group of hollow fiber membranes 2121a, the first fixing layer <NUM>-1a, and the first inner case 2123a constitute a first hollow fiber membrane cartridge 2120a, and the second group of hollow fiber membranes 2121b, the second fixing layer <NUM>-1b, and the second inner case 2123b constitute a second hollow fiber membrane cartridge 2120b.

As illustrated in <FIG>, ends of the first and second inner cases 2123a and 2123b are potted in the first and second fixing layers <NUM>-1a and <NUM>-1b, respectively, whereby relative positions of the first group of hollow fiber membranes 2121a and the first inner case 2123a and relative positions of the second group of hollow fiber membranes 2121b and the second inner case 2123b may be uniformly maintained.

In order to increase humidification capacity, the number of hollow fiber membranes <NUM> must be increased. However, in the first embodiment, which includes only a single hollow fiber membrane cartridge <NUM>, there is a problem in that, if the number of hollow fiber membranes <NUM> is increased, it is difficult for off-gas to be transmitted to hollow fiber membranes <NUM> located at the center.

In the second embodiment of the present disclosure, by contrast, two hollow fiber membrane cartridges 2120a and 2120b are disposed spaced apart from each other, whereby, even though the number of hollow fiber membranes 2121a and 2121b is increased, off-gas may be relatively uniformly transmitted to the hollow fiber membranes 2121a and 2121b. That is, on the assumption that the number of hollow fiber membranes is uniform, the structure of the second embodiment, which includes two hollow fiber membrane cartridges 2120a and 2120b, is advantageous in terms of utilization of the hollow fiber membranes, compared to the structure of the first embodiment, which includes a single hollow fiber membrane cartridge <NUM>.

The number of hollow fiber membrane cartridge(s) mounted in the mid-case <NUM> may be determined in overall consideration of the capacity of the fuel cell (or required humidification capacity), the size of the humidifier, and the weight of the humidifier.

Hereinafter, a method of manufacturing a humidifier <NUM> for a fuel cell according to an embodiment of the present disclosure will be described in more detail with reference to <FIG>.

First, as illustrated in <FIG>, a hollow fiber membrane cartridge <NUM>' having a first fixing layer <NUM>-<NUM>' in which ends of a plurality of hollow fiber membranes <NUM>' are potted is prepared.

The hollow fiber membrane cartridge <NUM>' may be manufactured by inserting at least a portion of each of the hollow fiber membranes <NUM>' into an inner case <NUM> and performing a dip casting process or a centrifugal casting process using liquid resin, such as liquid polyurethane resin. The first fixing layer <NUM>-<NUM>' in which the ends of the hollow fiber membranes <NUM>' are potted is formed as a result of hardening of the liquid resin.

When the dip casting process or the centrifugal casting process is performed, an end of the inner case <NUM> may be potted in the first fixing layer <NUM>-<NUM>' together with the ends of the hollow fiber membranes <NUM>'.

The inner case <NUM> may have first and second groups of holes H formed in a longitudinal direction thereof so as to be located on opposite sides.

Subsequently, as illustrated in <FIG>, the hollow fiber membrane cartridge <NUM>' is inserted into a mid-case <NUM> open at opposite ends thereof and having a step <NUM> formed at the inner circumferential surface thereof.

According to the embodiment of the present disclosure, the mid-case <NUM> has open ends, and has a simple closed curve-shaped traverse section. The mid-case <NUM> may have a partition wall configured to divide an inner space thereof into an off-gas introduction space and an off-gas discharge space located on opposite sides in a longitudinal direction, and the hollow fiber membrane cartridge <NUM>' may be inserted through a hole formed in the partition wall so as to be supported by the partition wall. At this time, the first group of holes H of the inner case <NUM> is located in the off-gas introduction space, and the second group of holes H of the inner case <NUM> is located in the off-gas discharge space.

In this case, off-gas that has entered the off-gas introduction space is introduced into the inner case <NUM> through the first group of holes H, flows toward the second group of holes H in the inner case <NUM>, moves to the off-gas discharge space through the second group of holes H, and is discharged from the mid-case <NUM>.

Subsequently, as shown in <FIG>, a bracket <NUM> is mounted on the step <NUM> of the mid-case <NUM>. As previously described, the mid-case <NUM> has a simple closed curve-shaped traverse section, and the bracket <NUM> may have a simple closed curve shape corresponding to the shape of the traverse section of the mid-case <NUM>.

The bracket <NUM> according to the embodiment of the present invention may be formed of metal, rigid plastic (e.g. polypropylene (PP), polyethylene terephthalate (PET), polystyrene (PS), polycarbonate (PC), or acrylic resin), or hard rubber.

Optionally, in order to form the primer layer <NUM>, at least a portion of the surface of the bracket <NUM> may be treated with a primer and may then be mounted on the step <NUM> of the mid-case <NUM>, or the bracket <NUM> may be mounted on the step <NUM> of the mid-case <NUM> and then the exposed surface thereof may be treated with a primer. As previously described, the primer may include a rubber adhesive component, an acrylic adhesive component, a polyurethane adhesive component, an epoxy adhesive component, a silicone adhesive component, a polyamide-based adhesive component, a polyimide-based adhesive component, or a mixture of two or more thereof.

Subsequently, as illustrated in <FIG>, a packing member <NUM> having a groove corresponding to the end of the mid-case <NUM> is mounted on the end of the mid-case <NUM> such that the end of the mid-case <NUM> is inserted into the groove and a portion of the packing member <NUM> comes into contact with the bracket <NUM>.

The packing member <NUM> may also have a simple closed curve shape corresponding to the shape of the traverse section of the mid-case <NUM>.

Optionally, in order to provide stronger internal and external sealing by forming the primer layer (i) between the packing member <NUM> and the mid-case <NUM>, (ii) between the packing member <NUM> and a fixing layer <NUM>, and/or (iii) between the packing member <NUM> and a cap <NUM>, at least a portion of the surface of the packing member <NUM> may be treated with the primer and may then be mounted on the end of the mid-case <NUM>.

Subsequently, as shown in <FIG>, a second fixing layer <NUM>-<NUM>' configured to fill the gap between the mid-case <NUM> and the end of the hollow fiber membrane cartridge <NUM>', the gap between the bracket <NUM> and the end of the hollow fiber membrane cartridge <NUM>', and the gap between the packing member <NUM> and the end of the hollow fiber membrane cartridge <NUM>' is formed.

The second fixing layer <NUM>-<NUM>' may be manufactured by fastening a potting cap (not shown) to the mid-case <NUM>, performing a dip casting process of injecting liquid resin, such as liquid polyurethane resin, into the potting cap and hardening the liquid resin in the state in which the potting cap is located under the mid-case <NUM>, and removing the potting cap. Alternatively, the second fixing layer <NUM>-<NUM>' may be formed through a centrifugal casting process.

Although the first and second fixing layers <NUM>-<NUM>' and <NUM>-<NUM>' may be formed of different liquid resins, it may be preferable for the first and second fixing layers to be formed of the same material (e.g. liquid polyurethane resin) in terms of adhesive strength therebetween.

According to the embodiment of the present disclosure, liquid resin (e.g. liquid polyurethane resin) used to form the second fixing layer <NUM>-<NUM>' may be hardened while being in contact with the bracket <NUM> and the packing member <NUM>, whereby the adhesive force of the second fixing layer <NUM>-<NUM>' with respect to them may be increased and thus internal sealing may be improved.

According to the embodiment of the present disclosure, since the bracket <NUM> is formed of a material that has excellent adhesive force with respect to the second fixing layer <NUM>-<NUM>', movement of gas through the interface therebetween (i.e. internal leakage) can be prevented, and therefore stronger internal sealing may be provided. In addition, when the bracket <NUM> surface-treated with the primer and/or the packing member treated with the primer is used, the adhesive strength between the bracket <NUM> and the second fixing layer <NUM>-<NUM>' and/or between the packing member <NUM> and the second fixing layer <NUM>-<NUM>' can be maximized, and therefore better internal sealing may be provided.

Subsequently, the first fixing layer <NUM>-<NUM>', the second fixing layer <NUM>-<NUM>', and the hollow fiber membranes <NUM>' are simultaneously cut along a cutting line CL of <FIG>, whereby hollow fiber membranes <NUM> configured such that ends thereof potted in a first fixing layer <NUM>-<NUM> surrounded by a second fixing layer <NUM>-<NUM> are open are obtained, as illustrated in <FIG>.

Subsequently, as illustrated in <FIG>, a cap <NUM> is fastened to the mid-case <NUM>. Specifically, the cap <NUM> is fastened to the mid-case such that the packing member <NUM> is compressed by the cap <NUM>.

As illustrated in <FIG>, the cap <NUM> according to the embodiment of the present disclosure may have a protrusion <NUM> formed at a position corresponding to the end of the mid-case <NUM>, which is inserted into the groove of the packing member <NUM>. The protrusion <NUM> more effectively compresses the packing member <NUM> together with the end of the mid-case <NUM>, whereby tighter external sealing is achieved.

In addition, according to the embodiment of the present disclosure, the bracket <NUM> has higher hardness than the packing member <NUM>, whereby the packing member <NUM> may be compressed when the cap <NUM> is fastened to the mid-case <NUM>.

That is, since the bracket <NUM> is supported by the step <NUM> of the mid-case <NUM> and has hardness (<NUM> to <NUM> Shore A, more preferably <NUM> to <NUM> Shore A) higher than the hardness of the packing member <NUM> (<NUM> to <NUM> Shore A, more preferably <NUM> to <NUM> Shore A), the bracket <NUM> may effectively apply pressure to the packing member <NUM> together with the cap <NUM> when the cap <NUM> is fastened to the mid-case <NUM> through the bolt <NUM> and the nut <NUM>. As a result, the portion of the packing member <NUM> disposed between the cap <NUM> and the bracket <NUM> (i.e. located in the mid-case <NUM>) is sufficiently compressed, whereby movement of gas through the interface between the packing member <NUM> and the bracket <NUM> (i.e. internal leakage) can be prevented, and therefore excellent internal sealing may be guaranteed.

Claim 1:
A humidifier (<NUM>) for a fuel cell, the humidifier (<NUM>) comprising:
a humidifying module (<NUM>) configured to humidify gas supplied from outside using moisture in off-gas discharged from a fuel cell stack; and
caps (<NUM>) coupled respectively to opposite ends of the humidifying module (<NUM>), wherein
the humidifying module (<NUM>) comprises:
a mid-case (<NUM>) open at opposite ends thereof, the mid-case (<NUM>) having a step (<NUM>) at an inner circumferential surface thereof;
a plurality of hollow fiber membranes (<NUM>) disposed in the mid-case (<NUM>);
a fixing layer (<NUM>) in which ends of the hollow fiber membranes (<NUM>) are potted;
a bracket (<NUM>) supported by the step (<NUM>) of the mid-case (<NUM>), the bracket (<NUM>) being in contact with the fixing layer (<NUM>); and
a packing member (<NUM>) having a groove into which the end of the mid-case (<NUM>) is inserted, the packing member (<NUM>) being in contact with the bracket (<NUM>),
the humidifier (<NUM>) characterized in that:
the packing member (<NUM>) is in contact also with the fixing layer (<NUM>).