JP2001202977A - Humidifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a humidifier, in which water permeability from a damp gas side to a dry gas side can be increased, and which can be used satisfactorily for humidifying a fuel cell. SOLUTION: In the humidifier, a large number of water permeable hollow fiber membranes arranged along a longitudinal direction of a housing, are housed in a housing, a moisture exchange between gases is performed by feeding the gases having different moisture contents inside and outside of the hollow fiber membrane, respectively, and dry gas having low moisture content is humidified. On the inner hollow fiber membrane, a structure for generating turbulence is provided. ON the inner wall of the hollow fiber membrane, the projections are provided. At a gas inlet to the inside the hollow fiber membrane, a twisting fin is provided. At the gas inlet to the inside the hollow fiber membrane, a step is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a humidifying device,
More specifically, the present invention relates to a humidifying device that utilizes a water-permeable hollow fiber membrane and can be suitably used for humidifying a fuel cell.

[0002]

2. Description of the Related Art There is a solid polymer type fuel cell. In recent years, a fuel cell, which has attracted attention as a power source of an electric vehicle, has a problem that the moisture of an off-gas, which is a humid gas discharged from the fuel cell, is low. A humidifier that exchanges moisture with dry air is used. As a humidifier used for such a fuel cell, a humidifier that consumes less power is suitable. In addition, a small mounting space, that is, compactness is required. Therefore, although there are various types of humidifiers such as ultrasonic humidification, steam humidification, vaporization humidification, and nozzle injection, as a humidification device used for a fuel cell, a device using a hollow fiber membrane is suitably used. .

As a humidifier using a conventional hollow fiber membrane,
For example, there is one disclosed in JP-A-7-71795. The humidifier will be described with reference to FIG. 8. The humidifier 100 has a housing 101. The housing 101 has a first inlet 102 for introducing dry air and a first outlet 1 for discharging dry air.
In the housing 101, a large number of hollow fiber membrane bundles 104, for example, 5000 hollow fiber membranes, are housed. At both ends of the housing 101, fixing portions 105 and 105 'for fixing both ends of the hollow fiber membrane bundle 104 in an open state are provided. Outside the fixing portion 105, a second inlet 1 for introducing moist air is provided.
A second outlet 107 is formed outside the fixing portion 105 ′ for discharging wet air from which moisture has been separated and removed by the hollow fiber membrane bundle 104. Further, the fixing portions 105 and 105 'are covered by a second head cover 108 and a second head cover 109, respectively. The second inlet 106 is formed in the first head cover 108, and the second outlet 107
Are formed on the second head cover 109.

In the humidifying apparatus 100 using the hollow fiber membrane configured as described above, when the moist air is supplied from the second inlet 106 and passes through each hollow fiber membrane constituting the hollow fiber membrane bundle 104. The moisture in the humid air is separated by the capillary action of the hollow fiber membrane and penetrates through the capillary of the hollow fiber membrane,
Move to the outside of the hollow fiber membrane. The wet air from which the water has been separated is discharged from the second outlet 107. On the other hand, dry air is supplied from the first inlet 102. The dry air supplied from the first inlet 102 is the hollow fiber membrane bundle 1
It passes outside the hollow fiber membrane that constitutes 04. Moisture separated from the humid air moves to the outside of the hollow fiber membrane, and the humidifies the dry air. Then, the humidified air is discharged from the first outlet 103.

[0005]

However, since the conventional humidifier 100 has a structure in which hollow fiber membranes are arranged in a straight line, the wet air is supplied to each hollow fiber constituting the hollow fiber membrane bundle. When passing through the inside of the membrane, the flow becomes laminar due to pressure loss and the moisture is separated from the wet air near the inner wall surface as it goes downstream, but the moisture is separated from the wet air in the central part where the flow velocity is fast. Without passing through the hollow fiber membrane as it is. As a result, there is a problem that the moisture permeability to the dry air side is reduced as a whole.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and can improve the moisture permeability from a wet gas side to a dry gas side, and can be suitably used for humidification of a fuel cell. It is an object of the present invention to provide a humidifying device capable of performing the following.

[0007]

The gist of the invention described in claim 1 for solving the above-mentioned problem is that a large number of water-permeable hollow fiber membranes arranged along the longitudinal direction of the housing are provided. A humidifying device that is housed in the housing and exchanges moisture between the gases by flowing gases having different moisture contents to the inside and the outside of the hollow fiber membrane, and humidifies a dry gas having a small moisture content. A turbulence generating structure is provided inside the hollow fiber membrane.

As described above, by providing the turbulent flow generating structure inside the hollow fiber membrane, a gas having a uniform water composition flows on the inner surface of the hollow fiber membrane. Therefore, the difference in water content between the gas flowing near the inside and the outside of the hollow fiber membrane can be increased as compared with the case where the flow is laminar, and the water flow from the wet gas side to the dry gas side can be increased. The transmittance increases. Any of a wet gas and a dry gas may flow inside the hollow fiber membrane, and the flow of the gas may be turbulent to increase the water permeability regardless of the flow. Note that the humidifier described in the embodiment of the present invention allows a humid gas, which is an off-gas of a fuel cell, to flow inside the hollow fiber membrane.

According to another aspect of the present invention, there is provided a turbulence generating structure in which a projection is provided on an inner wall surface of the hollow fiber membrane. Item 4. The humidifying device according to item 1.

As described above, a turbulent flow can be obtained by providing a projection on the inner wall surface of the hollow fiber membrane and causing the gas to collide with the projection. As a result, the moisture composition of the gas becomes uniform and flows on the inner surface of the hollow fiber membrane, so that the water permeability from the wet gas side to the dry gas side increases.

The gist of the invention described in claim 3 for solving the above problem is that the turbulence generating structure is provided with a twist fin at a gas inlet to the inside of the hollow fiber membrane. The humidifying device according to claim 1 or 2, wherein:

As described above, the turbulent flow can be formed by providing the twisted fins at the inlet of the gas into the hollow fiber membrane and agitating the gas flowing inside the hollow fiber membrane with the twisted fins. As a result, the moisture composition of the gas becomes uniform and flows on the inner surface of the hollow fiber membrane, so that the water permeability from the wet gas side to the dry gas side increases.

According to another aspect of the present invention, there is provided a turbulence generating structure in which a step portion is provided at an inlet portion of a gas into the hollow fiber membrane. The humidifying device according to any one of claims 1 to 3, characterized in that:

As described above, a turbulent flow can be obtained by providing a step at the inlet of the gas into the hollow fiber membrane and colliding the wet gas. As a result, the moisture composition of the gas flowing inside the hollow fiber membrane becomes uniform, and the gas flows on the inner surface of the hollow fiber membrane. Therefore, as described above, the difference in water content between the gas flowing near the inside and the outside of the hollow fiber membrane can be increased as compared with the case where the flow is laminar, and the dry gas The water permeability to the side increases.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a humidifier according to the present invention will be described.
An embodiment applied to a humidifier for a fuel cell will be described in detail with reference to the drawings. FIG. 1 is an overall configuration diagram of the fuel cell system. FIG. 2 is an explanatory diagram schematically illustrating the configuration of the fuel cell. FIG. 3 is a perspective view showing the configuration of the humidifier. FIG. 4 is a cross-sectional view showing a gas flow in the humidifier.

First, the overall configuration and operation of a fuel cell system to which a humidifier according to an embodiment of the present invention is applied will be described with reference to FIG. Fuel cell system FC
S is a fuel cell 1, a humidifier 2, a gas-liquid separator 3, an air compressor 4, a combustor 5, a fuel evaporator 6, a reformer 7, a CO remover 8, and a water / methanol mixed liquid storage tank (hereinafter referred to as a tank). T). The fuel cell 1
Is a solid polymer type.

In the fuel cell 1, humidified air as an oxidizing gas is supplied to the oxygen electrode side 1a, and a hydrogen-rich gas as a fuel gas is supplied to the hydrogen electrode side 1b to cause a chemical reaction between hydrogen and oxygen. Electric energy is extracted from chemical energy to generate electricity. Humidified air is generated by compressing and humidifying outside air (air) as dry gas. Here, the compression of air (dry air) is performed by the air compressor 4, and the humidification is performed by the humidifier 2 provided with a hollow fiber membrane module having a turbulence generating structure inside the hollow fiber membrane. Incidentally, the humidification of the dry air in the humidifier 2 is performed on the oxygen electrode side 1a of the fuel cell 1.
This is accomplished by exchanging moisture between the off-gas containing a large amount of moisture and the dry air containing a relatively small amount of moisture, which will be described in detail later. On the other hand, fuel gas is generated by evaporating, reforming, and removing CO from a mixture of water and methanol, which are raw fuels. Here, the evaporation of the raw fuel is performed by the fuel evaporator 6, the reforming is performed by the reformer 7, and the CO removal is performed by the CO remover 8. Incidentally, the raw fuel stored in the tank T is supplied to the fuel evaporator 6 via the pump P, and the raw fuel gas (reforming air mixed with the raw fuel gas) evaporated by the fuel evaporator 6 is supplied to the reformer 7. Thing)
And the fuel gas reformed by the reformer 7 is supplied to the CO remover 8. In the reformer 7, steam reforming and partial oxidation of methanol are performed in the presence of a catalyst.
Moreover, the presence of a catalyst in the CO remover 8, the CO is performed selectively oxidized is converted to CO _2. The CO remover 8 reduces the concentration of CO as much as possible. 1CO remover and N
o. It consists of two 2CO removers. Further, air for selective oxidation is supplied to the CO remover 8 from the air compressor 4.

The fuel cell 1 simultaneously generates off-gas on the hydrogen electrode side 1b containing unused hydrogen and off-gas on the oxygen electrode side 1a containing a large amount of water as a reaction product. Is used for humidifying the air in the humidifier 2 as described above, and then mixed with the offgas on the hydrogen electrode side 1b, and the moisture is removed by the gas-liquid separator 3. The off-gas from which water has been removed (mixed off-gas) is burned in the combustor 5 and used as a heat source for the fuel evaporator 6. The combustor 5 is supplied with auxiliary fuel (methanol or the like) and air to compensate for the lack of heat in the fuel evaporator 6 or to warm up the fuel cell system FCS when starting up.

Next, with reference to FIG. 2, the configuration and operation of the fuel cell which is the core of the fuel cell system FCS will be described. The configuration of the fuel cell 1 in FIG. 2 is schematically represented as one single cell (actually, the fuel cell 1 is configured as a stacked body in which about 200 single cells are stacked). As shown in FIG. 2, the fuel cell 1 is divided into a hydrogen electrode side 1b and an oxygen electrode side 1a with an electrolyte membrane 13 interposed therebetween, and each side is provided with an electrode containing a platinum-based catalyst, A hydrogen electrode 14 and an oxygen electrode 12 are formed. Then, a hydrogen-rich fuel gas generated from the raw fuel flows through the hydrogen electrode side gas passage 15, and humidified air humidified by the humidifier 2 as an oxidant gas flows through the oxygen electrode side gas passage 11. . As the electrolyte membrane 13, a solid polymer membrane, for example, a membrane using a perfluorocarbon sulfonic acid membrane as a proton exchange membrane as an electrolyte is known.
The electrolyte membrane 13 has a large number of proton exchange groups in the solid polymer, exhibits a low specific resistance of 20Ω-proton or less at room temperature by being saturated with water, and functions as a proton conductive electrolyte. Therefore, in the presence of the catalyst, protons generated by ionization of hydrogen at the hydrogen electrode 14 easily move through the electrolyte membrane 13 and reach the oxygen electrode 12. The protons that have reached the oxygen electrode 12 immediately react with oxygen ions generated from oxygen in the humidified air in the presence of a catalyst to generate water. The generated water is discharged together with the humidified air from the outlet on the oxygen electrode side 1a of the fuel cell 1 as an off-gas as a humid gas. At the hydrogen electrode 14, electrons e ⁻ are generated when hydrogen is ionized, and the generated electrons e ⁻ reach the oxygen electrode 12 via an external load M such as a motor. The humidified air thus humidified is supplied to the fuel cell 1 as an oxidizing gas when the electrolyte membrane 13 dries.
The reason for this is that the proton conductivity in the above becomes low and the power generation efficiency decreases. Therefore, in the fuel cell system FCS using the polymer electrolyte fuel cell 1, humidification has an important significance. By the way, the humidification on the fuel gas side is not necessary because the amount of water necessary for humidification of the fuel gas is added from the beginning to the raw fuel water / methanol mixture,
When the amount of water required for humidification is not added to the raw fuel, the humidifier 2 of the present invention can be applied.

Next, the configuration and operation of the humidifier 2 according to one embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 3 (a), the humidifier 2 has two hollow fiber membrane modules 21 each having a substantially columnar shape in parallel, and has a box-shaped one-side distributor 22 and a other-side distributor 23.
And is configured in a rectangular parallelepiped shape as a whole. The two hollow fiber membrane modules 21 and 21 are connected to one end distributor 22.
And the other end side distributor 23 horizontally disposes and is fixed at a predetermined interval. Further, each of the two hollow fiber membrane modules 21 and 21 supplies the dry air and discharges the off gas through the one end distributor 22, and the humidified air that is humidified through the other end distributor 23. Discharge and off-gas supply can be performed.

As shown in FIG. 3B, the hollow fiber membrane module 21 includes a housing 21a and a housing 2a.
1a includes a hollow fiber membrane bundle 21b. The housing 21a has a hollow cylindrical shape with both ends opened. The housing 21a is provided with a plurality of openings (approximately eight in the circumferential direction) near both ends thereof. On the other hand, the hollow fiber membrane bundle 21b housed in the housing 21a is formed by bundling thousands of hollow fiber membranes HF having a hollow passage shown in FIG. At the end), a hollow passage for the hollow fiber membrane HF is secured and an adhesive is used to prevent the hollow fiber membrane HF from being scattered. The portions 21g and 21h where the hollow fiber membrane bundle 21b is adhered to the housing 21a are called potting portions. The potting portions 21g and 21h allow the off-gas and the hollow fiber membrane to flow through the hollow passage inside the hollow fiber membrane HF. Dry air (humidified air) flowing outside the HF is not mixed. In the hollow fiber membrane module 21, one end face of the housing 21a is used as an off gas outlet 21d _out , and the other end face is used as an off gas inlet 21d _in . A circumferential opening at one end of the housing 21a is used as a dry air inlet 21c _in , and a circumferential opening at the other end is used as a humidifying air outlet 21c _out . By the way, such a hollow fiber membrane module 21
A bundle of a predetermined number of hollow fiber membranes HF, HF,... Is inserted into the housing 21a, the vicinity of both end faces is sufficiently adhered and fixed with an adhesive, and then the hollow fiber membranes HF, H
It is created by cutting and removing the bundle of F. The details of the turbulence generation structure provided inside the hollow fiber membrane HF will be described later.

The one end side distributor 22 is connected to the other end as described above.
Along with the side distributor 23, two hollow fiber membrane modules 21,
21 is fixed in a predetermined positional relationship.
22 is an off gas outlet 22a and a dry air inlet 22b.
Have. Off gas outlet 22a and each hollow fiber membrane module 2
1 off-gas outlet 21d_outIs the one-side distributor 22
Connected by an internal flow path 22a 'disposed inside
(See FIGS. 4A and 4B). Similarly, the dry air inlet 22b and
Dry air inlet 21c of each hollow fiber membrane module 21
_inIs an internal flow path 22 disposed inside the one end side distributor 22.
b '(see FIGS. 4 (a) and 4 (c)).

On the other hand, the other end distributor 23 also has an off gas inlet 23a and a humidified air outlet 23b. Ohuga entrance 2
3a and the off-gas inlet 21 of each hollow fiber membrane module 21
d _in is the internal flow path 23 disposed inside the other end side distributor 23.
a '(see FIG. 4A). Similarly, the humidified air outlet 23b and the humidified air outlet 21c _out of each hollow fiber membrane module 21 are connected by an internal flow path 23b 'disposed inside the other end distributor 23 (FIG. 4 (a)). reference).

The hollow fiber membrane HF used in the hollow fiber membrane module 21 has an inner diameter of 300 as shown in FIG.
It is a thin cylindrical hollow fiber having a diameter of about micrometer to 700 micrometers. Since the hollow fiber membrane HF is thin, the membrane packing density per hollow fiber membrane module is large and the hollow fiber membrane HF can withstand high pressure. The principle of separation of water by the hollow fiber membrane HF is that the off-gas, which is a wet gas, is supplied to the hollow fiber membrane HF.
When flowing through the inside of the tube, the vapor pressure is reduced in the capillary of the hollow fiber membrane HF, so that water vapor is condensed in the capillary and becomes condensed water. This utilizes the capillary action of the hollow fiber membrane HF, in which the condensed water is sucked out by capillary action and permeates to the dry gas side flowing outside the hollow fiber membrane.

Next, referring to FIG. 3 and FIG.
The operation of will be described. The off-gas as a humid gas enters the humidifier 2 through an off-gas inlet 23a of the other end distributor 23,
The gas reaches the off-gas inlet 21d _in of the hollow fiber membrane module 21 via the internal flow path 23a '. The off-gas is branched from the hollow fiber membranes HF constituting the hollow fiber membrane bundle 21b.
・ It flows through the inside of HF. At this time, the off-gas gives contained moisture to dry air flowing outside the hollow fiber membrane HF. The off gas flowing inside the hollow fiber membrane HF exits the hollow fiber membrane HF from the off gas outlet 21d _out . The off-gas that has escaped from each of the hollow fiber membranes HF, HF,... Merges and reaches the off-gas outlet 22 a through the internal flow path 22 a ′, and goes to the gas-liquid separation device 3 at the subsequent stage. As described above, since the internal flow path 23a 'of the other end side distributor 23 is connected to each of the two hollow fiber membrane modules 21 and 21, the off-gas is distributed to each hollow fiber membrane module 21. You. In this regard, the internal flow path 22a 'of the one end distributor 22 is the same, and therefore, the description is omitted.

On the other hand, the dry air as the dry gas enters the humidifier 2 through the dry air inlet 22b of the one end distributor 22.
It reached the drying air inlet 21c _in the hollow fiber membrane module 21 via the internal flow path 22b '. The dry air spreads over the entire inside of the housing 21a from here, and the hollow fiber membrane H
Flow outside of F. At this time, the dry air is supplied with moisture from the off gas and humidified to become humidified air. The humidified air exits the housing 21a through the humidified air outlet 21c _out , passes through the internal flow path 23b ', and passes through the humidified air outlet 23c.
and reaches the gas-liquid separation device 3 at the subsequent stage. As described above, since the internal flow path 22b 'of the one end side distributor 22 is connected to each of the two hollow fiber membrane modules 21 and 21, the dry air is distributed to each hollow fiber membrane module 21. You. In this regard, the internal flow path 23 of the other end side distributor 23
Since b ′ is the same, the description is omitted.

By packaging the hollow fiber membrane module 21 in this manner, it is possible to save space while ensuring easy handling.

Next, an embodiment of a turbulence generating structure provided inside the water-permeable hollow fiber membrane HF used in the humidifier 2 according to the present invention is shown in FIGS. 5 (a) to 5 (c). This will be described with reference to FIG. A first embodiment of the turbulence generating structure provided inside the hollow fiber membrane HF will be described with reference to FIG. In the turbulent flow generation structure of the first embodiment, projections 31a are provided on the entire surface at appropriate intervals along the inner wall surface of a cylindrical hollow fiber membrane 31 through which an off-gas as a wet gas flows. The sectional shape of the protrusion 31a is shown in FIG.
The hollow fiber membrane 3 is a semicircle in FIG.
Anything may be used as long as it protrudes toward the center side of 1. In order to provide the projection 31a on the inner wall surface, a method of sending fine particles coated with an ultraviolet curable resin into the hollow fiber membrane 31 and irradiating ultraviolet rays to fix the fine particles to the inner wall surface of the hollow fiber membrane 31 can be applied. As the UV-curable resin, a resin that does not dissolve in water or a solvent, for example, a non-colored UV-curable oligomer manufactured by Kyoeisha Chemical Co., Ltd. is used.

As described above, the protrusions 3 are formed on the inner wall surface of the hollow fiber membrane 31.
By providing 1a, the off gas, which is the wet gas flowing on the inner wall surface side, collides with the projection 31a and is appropriately mixed and stirred with the off gas flowing on the center side, so that turbulent flow can be achieved. As a result, the water composition in the off-gas becomes uniform and flows on the inner surface of the hollow fiber membrane 31, so that the water permeability from the off-gas side to the dry air side is higher than in the case where there is no protrusion. In FIG. 5A, the off-gas flows in a countercurrent to the flow of the dry air, but may flow in a parallel flow.

A second embodiment of the turbulence generating structure provided inside the hollow fiber membrane HF will be described with reference to FIG. In the turbulent flow generation structure of the second embodiment, the twist fins 41a are press-fitted into the cylindrical hollow fiber membrane 41 at the inlet of the off-gas, which is the wet gas. Twist fin 41
Each of the shapes a has a shape obtained by twisting a rectangular plate by 180 degrees. The twisting direction is shown in FIG. 5B as a fin twisted in only one direction, but the off-gas is combined so that the left element twisted to the left and the right element twisted to the right are connected at 90 degrees. Fins may be provided. As the material of the torsion fin 41a, a metal fin such as stainless steel or titanium is used, but a resin fin or a ceramic fin can also be used.

As described above, the turbulent flow can be obtained by providing the twisted fin 41a at the inlet of the off-gas, which is the wet gas of the hollow fiber membrane 41, and stirring the off-gas by the twisted fin 41a. As a result, the water composition in the off-gas becomes uniform and flows on the inner surface of the hollow fiber membrane, so that the water permeability from the off-gas side to the dry air side is higher than in the case where there is no twist fin 41a. In FIG. 5A, the off-gas flows in a countercurrent to the flow of the dry air, but may flow in a parallel flow. However, in this case, the twist fin 4
The position where 1a is provided is a position on the opposite side of FIG.

A third embodiment of the turbulence generating structure provided inside the hollow fiber membrane HF will be described with reference to FIG. The turbulent flow generation structure according to the third embodiment has a structure in which a part of an inner wall surface of an inlet portion of a cylindrical hollow fiber membrane 51 into which an off-gas as a wet gas is introduced is crushed, and a step portion 51a is provided on the inner wall surface. It is. In FIG. 5C, the step portion 51a is provided on one side, but may be provided on both sides so as to be asymmetric with respect to the axis of the hollow fiber membrane 51.

Since the step 51a is provided on the inner wall surface, the off-gas collides with the step 51a at the inlet and is disturbed, so that a turbulent flow can be obtained. as a result,
Since the water composition in the off-gas becomes uniform and flows on the inner surface of the hollow fiber membrane 51, the water permeability from the off-gas side to the dry air side increases. In FIG. 5C, the off-gas flows countercurrent to the flow of the dry air, but may flow in parallel.

By providing the turbulent flow generating structure with the projections, twisted fins and step portions inside the hollow fiber membrane,
When an off-gas is introduced into the hollow fiber membrane, turbulence tends to occur. As a result, the water composition in the off-gas becomes uniform and flows on the inner surface of the hollow fiber membrane, so that the water permeability from the off-gas side to the dry air side increases. Further, by providing a combination of these turbulence generating structures inside the hollow fiber membrane, the water composition in the off-gas becomes more uniform, so that drying is performed from the off-gas side more than when the turbulence generating structure is provided alone. The water permeability to the air side increases.

In the present invention, the present inventor has also found a method of manufacturing a hollow fiber membrane module suitable for solving the following problems which have been problems in the prior art, and introduces the method. The invention described above is applied to a hollow fiber membrane module having a structure in which the hollow fiber membranes are straightly aligned and bundled, but in practice, the hollow fiber membrane itself is very Thin and long, the hollow fiber membranes are likely to be entangled with each other or turbulent due to twisting of the hollow fiber membrane itself. As a result, dry air passing outside the hollow fiber membrane bundle does not reach the entire membrane and is dried from the off-gas side. There has been a problem that the water permeability to the air side is reduced and the flow path of the dry air is partially closed, so that the pressure loss increases. Therefore, a method of manufacturing a hollow fiber membrane module that can align hollow fiber membranes straight has been desired.

Hereinafter, a method of manufacturing a hollow fiber membrane module that can align hollow fiber membranes straight when actually manufacturing a hollow fiber membrane module will be described with reference to FIGS. 6 and 7. FIG. The first method for manufacturing a hollow fiber membrane module that can arrange hollow fiber membranes straight is a method for combining hollow fiber membranes having different thicknesses. The first step of the manufacturing method is
As shown in FIG. 6, with the thickest hollow fiber membrane 61 as the core,
Another thin hollow fiber membrane 6 surrounding the hollow fiber membrane 61
The one provided with 2 is referred to as 1 unit 60. For example, one hollow fiber membrane having a diameter ratio twice as large as 20 to 30 thin hollow fiber membranes is mixed. In the second step of the manufacturing method, a plurality of units 60 are loaded in the housing of the hollow fiber membrane module.

With this configuration, the thickest hollow fiber membrane 61 is less likely to bend than the thinner hollow fiber membrane 62, and thus plays the role of a core. The disturbance of the film 62 is suppressed. As a result, the hollow fiber membranes 61 and 62 in the hollow fiber membrane module can be aligned straight, and the dry air flowing outside the hollow fiber membrane bundle spreads over the entire hollow fiber membrane bundle. The water permeability to the air side is improved, and the pressure loss in the flow path of the dry air is also reduced.

A second method for manufacturing a hollow fiber membrane module in which hollow fiber membranes can be aligned straight is a method that utilizes static electricity in the manufacturing process. A method for manufacturing a hollow fiber membrane module using static electricity in the manufacturing process will be described with reference to FIG. <First Step> One side of the plurality of hollow fiber membranes 71 is fixed to the fixing portion 71.
a (see FIG. 7A). <Second Step> The hollow fiber membrane 71 is suspended vertically with the fixing part 71a facing upward (see FIG. 7B). Hanging in the vertical direction in this manner makes it difficult for the hollow fiber membranes 71 to sag one by one. <Third Step> The hollow fiber membrane 71 is charged with static electricity (see FIG. 7C). As a device used for charging, for example, a belt-type generator used in science experiments can be used. By charging the static electricity, the hollow fiber membranes have the same charge (positive charge).
Entanglement of the hollow fiber membranes and slack of the hollow fiber membrane itself are eliminated. <Fourth Step> The electrostatic electrode of the opposite charge (negative charge) to the charge (positive charge) of the hollow fiber membrane 71 is brought close to a distance where corona discharge does not occur (see FIG. 7D). Here, the area of the electrostatic electrode 71b needs to be at least four times the diameter of the fixing portion 71a for adhering and fixing the hollow fiber membrane. <Fifth Step> In this way, by bringing the electrostatic electrode 71b of the opposite charge (negative charge) to the charge (positive charge) of the hollow fiber membrane 71 close to a predetermined distance,
The hollow fiber membrane 71 can be fixed in the space by electrostatic attraction (see FIG. 7E). <Sixth Step> Next, a bundle of hollow fiber membranes 71 spread by the repulsion of static electricity by covering a conductive hollow cylinder 71c (for example, a metal cylinder) from above the fixing portion 71a is used.
c (see FIGS. 7 (e) and 7 (f)). By doing so, the electrostatic charge of the hollow fiber membrane 71 housed inside the hollow cylinder 71c is eliminated by the electrostatic shielding effect, so that the bundle of hollow fiber membranes is kept aligned in the cylinder. Can be suitably stored. <Seventh Step> The other side of the hollow fiber membrane 71 is
1d (see FIG. 7 (g)), and the fixing portion 71d is housed in a hollow cylinder 71c (see FIG. 7 (h)). Manufacturing of hollow fiber membrane module completed. By manufacturing the hollow fiber membrane module in this manner, the hollow fiber membranes can be arranged neatly and a hollow fiber membrane module having a high membrane packing density can be manufactured. As a result, the dry air passing outside the hollow fiber membrane bundle is distributed throughout the membrane, so that the water permeability from the off-gas side to the dry air side is improved, and the pressure loss in the dry air flow path is also reduced. .

A third method of manufacturing a hollow fiber membrane module capable of aligning the hollow fiber membranes straight is a method of setting the filling rate of the hollow fiber membrane HF in the hollow fiber membrane module to 30% to 40% ( (See FIG. 3). Hollow fiber membrane module 21
The reason for setting the filling rate of the hollow fiber membranes HF in the inside of the hollow fiber membrane module 21 from 30% to 40% is that when the filling rate of the hollow fiber membranes HF in the hollow fiber membrane module 21 is 30% or less, each hollow fiber The gap between the membranes becomes large, and the hollow fiber membrane easily becomes slack. On the other hand, when the filling rate of the hollow fiber membranes HF in the hollow fiber membrane module 21 exceeds 40%, the gap between the hollow fiber membranes becomes narrower, and the once entangled hollow fiber membranes are replaced and aligned. Is lost. As described above, by setting the filling rate of the hollow fiber membranes in the hollow fiber membrane module 21 from 30% to 40%, an alignment effect of the hollow fiber membranes HF can be obtained. As a result, the hollow fiber membrane module 2
1, since the dry air passing through the outside of the hollow fiber membrane bundle spreads over the entire membrane, the water permeability from the off gas side to the dry air side is improved, and the dry air The pressure loss in the flow path is also reduced.

The method of manufacturing a hollow fiber membrane module capable of aligning hollow fiber membranes straight when actually manufacturing a hollow fiber membrane module has been described above. However, these methods described above may be appropriately combined. Can also. The above-described method for manufacturing a hollow fiber membrane module is not limited to the hollow fiber membrane module, and can be applied to a case where a membrane module using another membrane is manufactured.

As described above, the present invention can be widely modified without being limited to the above-described embodiment. For example, the humidifier can be applied not only to fuel cells but also to other uses. Alternatively, off-gas, which is a wet gas, may flow outside the hollow fiber membrane, and dry air (humidified air), which is a dry gas, may flow inside. Further, in the embodiment, the off-gas and the dry air are caused to flow in countercurrent, but they may flow in parallel.

Here, the respective advantages when the dry air and the off-gas are caused to flow in countercurrent or cocurrent are described.
An advantage of flowing dry air and off-gas in countercurrent is that the difference in temperature concentration in the hollow fiber membrane can be made uniform, so that the water permeability is improved. Further, since the gas inlet and the outlet are opposed to each other, the layout of the gas pipe is improved. Furthermore, since the heat exchange rate by the hollow fiber membrane is improved, the cooling performance of the gas is improved, and since the heat exchange rate is high, it is easy to adjust the temperature of the outlet of the dry air to the temperature of the off gas, so that the temperature is controlled Becomes easier. Therefore, it becomes easy to control the humidity of the air supplied to the fuel cell. On the other hand, the advantage of flowing dry air and off-gas as co-current is that the dry air and off-gas have a high difference in humidity concentration at the inlet portion, so that the humidification efficiency is improved and the overall length of the hollow fiber membrane itself can be shortened. Since the apparatus can be downsized, it is easy to align and bundle the hollow fibers, which contributes to cost reduction.
Further, since the heat exchange rate of the dry air decreases, the temperature of the gas supplied to the fuel cell at the time of high output can be set higher. Therefore, the efficiency of the fuel cell can be improved.

Finally, a supplementary explanation will be given on the temperature control function of the humidifier. For example, the temperature of dry air compressed by an air compressor such as a supercharger changes between approximately 30 ° C. (when the fuel cell is idling) and 120 ° C. (when the fuel cell is at maximum output). On the other hand, the fuel cell is operated at about 80 ° C. under temperature control, and off-gas of about 80 ° C. + α is discharged. When this off-gas and the dry air compressed by the air compressor are passed through a humidifier, heat transfer occurs together with moisture in the hollow fiber membrane, and the dry air reaches a temperature close to the off-gas (that is, a stable temperature close to the operating temperature of the fuel cell). Humidified air at a temperature equal to the temperature of the fuel cell). That is,
Dry air is humidified and heated by the humidifier at the time of low output such as idling of the fuel cell and supplied to the fuel cell, and humidified and cooled by the humidifier at high output such as the maximum output of the fuel cell, and is stable. It is supplied to the fuel cell as humidified air in a temperature range. Therefore, the fuel cell can be operated under suitable temperature conditions by the temperature control function of the humidifier, and the power generation efficiency of the fuel cell increases. Further, when an intercooler is attached to the discharge side of the air compressor, the dry air compressed by the air compressor is cooled (or heated) to approximately 50 ° C. (during fuel cell idling) to 60 ° C. (fuel (When the battery is at its maximum output). If the dry air that has passed through the intercooler is passed through a humidifier through which off-gas (80 ° C. + α) flows, the dry air is humidified and temperature-adjusted (heated) in the hollow fiber membrane, and has a temperature close to the off-gas, Humidified air in a stable temperature range close to the operating temperature of the fuel cell is supplied to the fuel cell. Therefore, even when the intercooler is attached, the fuel cell can be operated under suitable temperature conditions by the temperature control function of the humidifier, and the power generation efficiency of the fuel cell is increased.

[0044]

As is apparent from the above configuration and operation, (1) According to the first aspect of the present invention, by providing the turbulent flow generating structure inside the hollow fiber membrane, the water content is reduced. Since a gas having a uniform composition flows on the inner surface of the hollow fiber membrane, the difference in water content between the gases flowing near the inside and outside of the hollow fiber membrane can be increased, and the water content can be increased. The water permeability from the wet gas side with much moisture to the dry gas side with little moisture content increases. (2) According to the second aspect of the invention, a turbulent flow can be obtained by providing a projection on the inner wall surface of the hollow fiber membrane and causing the wet gas to collide with the projection. As a result, since the water composition of the gas becomes uniform and flows on the inner surface of the hollow fiber membrane, the water permeates from the wet gas side having a high water content to the dry gas side having a low water content as described above. Rate is higher. (3) According to the third aspect of the present invention, a turbulent flow can be obtained by providing a twisted fin at the gas inlet to the inside of the hollow fiber membrane and stirring the wet gas with the twisted fin. As a result, since the water composition of the wet gas becomes uniform and flows on the inner surface of the hollow fiber membrane, as described above, water permeation from the wet gas side having a high water content to the dry gas side having a low water content is performed. Rate is higher. (4) According to the fourth aspect of the present invention, a turbulent flow can be obtained by providing a step at the gas inlet into the hollow fiber membrane and causing the wet gas to collide with the step. As a result, the water composition of the body flowing inside the hollow fiber membrane becomes uniform and flows on the inner surface of the hollow fiber membrane. The water permeability to the dry gas side with less moisture increases.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a fuel cell system to which a humidifier according to the present invention is applied.

FIG. 2 is an explanatory diagram schematically illustrating a configuration of a fuel cell humidified by a humidifier according to the present invention.

FIG. 3A is a perspective view illustrating a configuration of a humidifier according to the present invention. (B) It is a perspective view of a hollow fiber membrane module. (C) It is an enlarged view of a hollow fiber membrane.

FIG. 4A is a cross-sectional view showing a gas flow in a humidifier according to the present invention. (B) It is XX sectional drawing of Fig.4 (a). (C) It is YY sectional drawing of FIG.4 (a).

FIG. 5 (a) is a cross-sectional view showing a first embodiment of a turbulent flow generation structure provided inside a hollow fiber membrane used in a humidifier according to the present invention. (B) It is sectional drawing which shows 2nd Embodiment of the turbulence generation structure provided inside the hollow fiber membrane used by the humidifier which concerns on this invention. (C) It is sectional drawing which shows 3rd Embodiment of the turbulence generation structure provided inside the hollow fiber membrane used by the humidifier which concerns on this invention.

FIG. 6 is a view for explaining a first method of manufacturing a hollow fiber membrane module capable of storing a hollow fiber membrane used in the humidifier according to the present invention in a straight line.

FIG. 7 is a view for explaining a second method for manufacturing a hollow fiber membrane module capable of storing a hollow fiber membrane used in the humidifier according to the present invention in a straight line.

FIG. 8 is a cross-sectional view showing a humidifier using a conventional hollow fiber membrane.

[Explanation of symbols]

2 Humidifier (humidifier for fuel cell) 21 Hollow fiber membrane module 21a Housing 21b Hollow fiber membrane bundle 21c _in dry air inlet 21c _out humidifier air outlet 21d _in off gas inlet 21d _out off gas outlet 22 one end distributor 22a Off gas outlet 22a 'Internal flow path 22b Dry air inlet 22b' Internal flow path 23 Other end side distributor 23a Off gas inlet 23a 'Internal flow path 23b Humidified air outlet 23b' Internal flow path 31a Projection 41a Twisted fin 51a Step HF, 31 , 41, 51, hollow fiber membrane

Continued on the front page (72) Inventor Mikihiro Suzuki 1-4-1 Chuo, Wako-shi, Saitama Pref. Inside of Honda R & D Co., Ltd. (72) Inventor Toshikatsu Katagiri 1-4-1 Chuo, Wako-shi, Saitama Co., Ltd. Honda R & D F term (reference) 3L055 AA10 BA01 DA05 4D006 GA41 HA02 JA02A JA02Z JA30A JA70A MA01 MB02 MB04 PB65 PC80 5H026 AA06 5H027 AA06 BA08

Claims (4)

[Claims] 1. A plurality of water-permeable hollow fiber membranes arranged along a longitudinal direction of a housing are housed in the housing,
In a humidifier for humidifying a dry gas having a small moisture content, a gas having a different moisture content flows through the inside and the outside of the hollow fiber membrane to exchange moisture between the gases, and the inside of the hollow fiber membrane is humidified. A humidifier comprising a turbulence generating structure. 2. The humidifier according to claim 1, wherein the turbulence generating structure has a projection on an inner wall surface of the hollow fiber membrane. 3. The humidifier according to claim 1, wherein the turbulence generating structure includes a twist fin at a gas inlet into the hollow fiber membrane. 4. The turbulent flow generating structure according to claim 1, wherein a step portion is provided at a gas inlet to the inside of the hollow fiber membrane. The humidifying device as described.