JP2010071619A - Humidifying device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent breakage of a hollow yarn film at a low temperature without degrading humidifying performance. <P>SOLUTION: A bypass passage as a clearance is formed in an upper section in a storage case 6 by loosening of the hollow yarn film 4 because the storage case 6 contracts as an environmental temperature is lowered. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a humidifier.

  Conventionally, a humidifier using a hollow fiber membrane is known. This humidifier utilizes a capillary condensation action on the pores inside the hollow fiber membrane, and gas that flows inside the hollow fiber membrane (eg, dry gas) and gas that flows outside the hollow fiber membrane (eg, wet gas) The dry gas is humidified by the wet gas by exchanging moisture with the gas. This type of humidifier includes, for example, a hollow fiber membrane module in which a bundle of hollow fiber membranes is accommodated in a cylindrical case.

  For example, in Patent Document 1, from the viewpoint of improving the strength of a hollow fiber membrane, a plurality of hollow fiber membranes are bundled by a focusing member around a rigid rod, and a set of the bundled hollow fiber membranes is placed in a case. Contained.

For the purpose of improving humidification performance, a so-called cross-flow type humidifier is also known in which the gas flowing outside the hollow fiber membrane is supplied so as to be orthogonal to the gas flowing inside the hollow fiber membrane.
JP 2004-311287 A

  However, the crossflow humidifier has a problem that bending stress is easily generated in the hollow fiber membrane by the gas flowing outside the hollow fiber membrane. In particular, when the ambient temperature such as the outside air falls to a low temperature that freezes the water retained in the pores inside the hollow fiber membrane, the hollow fiber membrane is weakened and may break. There is.

  The present invention has been made in view of such circumstances, and an object thereof is to suppress breakage of the hollow fiber membrane at a low temperature without causing a reduction in humidification performance.

  In order to solve such a problem, the present invention provides a hollow fiber membrane module in which each of the hollow fiber membranes is in a first state in which each of the hollow fiber membranes is linearly aligned along the axial direction and each of the hollow fiber membranes is loosened. Setting means is provided for setting a second state in which a bypass path as a gap is formed in the storage case in response to the environmental temperature.

  According to the present invention, each of the hollow fiber membranes is slackened in response to the environmental temperature, and a bypass path is set in the storage case. Thereby, the bending stress which acts on each hollow fiber membrane can be relieved. Therefore, breakage of the hollow fiber membrane at a low temperature can be suppressed without deteriorating the humidification performance.

(First embodiment)
FIG. 1 is a perspective view schematically showing a humidifier 1 according to a first embodiment of the present invention. This humidifier 1 is suitable as a humidifier used in, for example, a fuel cell system. A fuel cell system mainly includes a fuel cell stack that generates electricity by electrochemically reacting a fuel gas (for example, hydrogen) and an oxidant gas (for example, air). The fuel cell stack is configured by sandwiching a fuel cell structure in which an oxidant electrode and a fuel electrode are opposed to each other with a separator and an electrode catalyst composite in between, and laminating a plurality of these. As an electrolyte, a solid polymer electrolyte is often used in consideration of high energy density, low cost, light weight, and the like. The solid polymer electrolyte is composed of, for example, an ion conductive polymer membrane such as a fluororesin ion exchange membrane, and functions as an ion conductive electrolyte when saturated with water. Therefore, in such a fuel cell system, the solid polymer electrolyte membrane of each cell is humidified by supplying the reaction gas (fuel gas or oxidant gas) to the fuel cell stack while being humidified by the humidifier. .

  FIG. 2 is an exploded perspective view schematically showing the humidifier 1 shown in FIG. The humidifying device 1 of the present embodiment supplies a wet gas, for example, a reactive gas containing water vapor discharged from the fuel cell stack (hereinafter referred to as “second gas G2”) and a dry gas, for example, a fuel cell stack. The first gas G1 is humidified by exchanging moisture with the reaction gas (hereinafter referred to as “first gas G1”). The humidifier 1 includes a hollow fiber membrane module 2 that uses a hollow fiber membrane as a water permeable membrane, and a housing 3 that houses the hollow fiber membrane module 2 therein.

  The hollow fiber membrane module 2 is mainly composed of a hollow fiber membrane bundle 5 configured by bundling a plurality of hollow fiber membranes 4 and a rectangular tubular storage case 6 that accommodates the hollow fiber membrane bundle 5 therein. Has been.

  FIG. 3 is a perspective view schematically showing a cross-sectional state of the hollow fiber membrane module 2. The hollow fiber membrane bundle 5 is configured by bundling a plurality of hollow fiber membranes 4. Each hollow fiber membrane 4 has a flow passage (not shown), which is a pore penetrating in the longitudinal direction (axial direction), and has an elongated straw shape with a circular cross section. .

  In the hollow fiber membrane module 2, the first gas G1 is supplied to the inside (flow passage) of the hollow fiber membrane 4, and the second gas G2 containing moisture is supplied to the outside (outside) of the hollow fiber membrane 4. In the humidifier 1 of the present embodiment, a so-called cross flow method is adopted in which the second gas G2 flows in a direction that intersects (specifically, substantially perpendicular) with the flow direction of the first gas G1.

  In the hollow fiber membrane 4, moisture is condensed (capillary condensation) in pores (capillaries) formed in the thickness direction of the hollow fiber membrane 4, and moisture is absorbed by the difference in water vapor partial pressure inside and outside the hollow fiber membrane 4. It penetrates from the outside to the inside. The flow of the air in the second gas G2 is inhibited by the condensation of moisture in the pores in the hollow fiber membrane 4, and as a result, only the water vapor in the wet gas selectively moves to the first gas G1 side. To Penetrate. The permeated water comes into contact with the first gas supplied to the inside of the hollow fiber membrane 4 and vaporizes, whereby the first gas G1 is humidified. The hollow fiber membrane module 2 supplies the second gas G2 that is a wet gas into the hollow fiber membrane 4 (flow passage) and flows the first gas G1 that is a dry gas to the outside of the hollow fiber membrane 4. Water exchange can be performed.

  FIG. 4 is a perspective view schematically showing the hollow fiber membrane module 2. The storage case 6 has a rectangular tube shape with both ends opened, and has a function of storing the hollow fiber membrane bundle 5 therein. In the present embodiment, the storage case 6 contracts in the longitudinal direction of the hollow fiber membrane 4 as the environmental temperature approaches a low temperature at which water condensed in the pores of the hollow fiber membrane 4 is frozen for reasons that will be described later. It is formed by the member to do. An example of such a member is a metal member such as aluminum.

  In the storage case 6, gas holes 8 and 9 are formed in a pair of opposing side surfaces 6 a and 6 b, that is, a pair of surfaces constituting the long side of the opening. Each gas hole 8 formed in one side surface 6a (hereinafter, referred to as “second gas introduction surface 6a” as necessary) allows the second gas G2 to pass inside the hollow fiber membrane bundle 5 (between the hollow fiber membranes 4). It functions as a gas introduction hole for flowing into the gap. On the other hand, each gas hole 9 formed in the opposite other side surface 6b (hereinafter referred to as “second gas discharge surface 6b” if necessary) passes through the inside of the hollow fiber membrane bundle 5. It functions as a gas discharge hole for discharging the gas G2 out of the hollow fiber membrane module 2. A plurality of gas holes 8 and 9 are formed on almost the entire side surfaces 6a and 6b, and part of upper and lower surfaces (that is, a pair of surfaces constituting the short side of the opening) 6c and 6d facing each other. It is formed to the position where it entered.

  In such a hollow fiber membrane module 2, when the hollow fiber membrane bundle 5 filled in the storage case 6 is captured in a cross section perpendicular to the longitudinal direction of the hollow fiber membrane 4, each hollow fiber membrane 4 is within the cross section. Both ends thereof are fixed with a potting agent (adhesive) so as to be uniformly distributed. Moreover, the hollow fiber membrane bundle 5 accommodated in the storage case 6 is fixed to the inner wall surface of the case with a potting agent at both ends in the longitudinal direction, and other portions are not adhered. At this time, the hollow fiber membranes 4 are arranged so that the longitudinal direction thereof and the axial direction of the storage case 6 are parallel to each other, and the hollow fiber membranes 4 are not twisted and entangled with each other. It is configured as follows. Therefore, a constant gap is formed between each hollow fiber membrane 4 and the adjacent hollow fiber membrane 4 over the entire lengthwise direction of the hollow fiber membrane 4, and the gap formed between the hollow fiber membranes 4 is: The storage cases 6 are uniformly distributed along the entire length of the cross section obtained by dividing the storage cases 6 in the longitudinal direction along the four rows of the hollow fiber membranes. The second gas G2, which is a wet gas, flows through this gap. That is, the site | part except the both ends of the hollow fiber membrane bundle 5 functions as a humidification field which humidifies the 1st gas G1 with the 2nd gas G2.

  1 and 2, the housing 3 has a housing 12, a first gas introduction manifold 14 having an introduction port 13 for the first gas G1, and an exhaust port 15 for the first gas G1. The first gas discharge manifold 16, the second gas introduction manifold 18 having the second gas G2 introduction port 17, and the second gas discharge manifold 20 having the second gas G2 discharge port 19 Become.

  The housing 12 is a case for housing the hollow fiber membrane module 2 therein, and has a quadrangular prism shape with both ends opened.

  The first gas introduction manifold 14 is attached so as to close one opening 21 formed in the front-rear direction of the housing 12. The seal between the first gas introduction manifold 14 and the housing 12 employs a shaft seal structure using, for example, an O-ring at the inner end of the opening 21. The first gas introduction manifold 14 is formed with an introduction port 13 for introducing the first gas G1 into the hollow fiber membrane module 2 in the housing 12.

  The first gas discharge manifold 16 is attached so as to close the other opening 23 formed in the front-rear direction of the housing 12. The seal between the first gas discharge manifold 16 and the housing 12 employs a shaft seal structure using, for example, an O-ring at the inner end of the opening 23. The first gas discharge manifold 16 is formed with a discharge port 15 for discharging the first gas G1 that has passed through the flow path of each hollow fiber membrane 4 to the outside of the housing 12.

  The second gas introduction manifold 18 is attached so as to close an opening (not shown) formed on one side surface of the housing 12. The second gas introduction manifold 18 is formed with an introduction port 17 for introducing the second gas G2 into the housing 12. The seal between the second gas introduction manifold 18 and the housing 12 is similarly sealed with a shaft seal structure. By the second gas introduction manifold 18, the second gas introduction port 17 side and the second gas introduction surface 6 a of the storage case 6 face each other.

  Further, the second gas introduction manifold 18 is provided with a step portion 26 in the middle of the gas introduction passage 25 from the introduction port 17 for introducing the second gas G2 to the second gas introduction surface 6a of the storage case 6. ing. The step portion 26 is formed by recessing a part of the second gas introduction manifold 18 inward (on the casing 12 side), and is provided in the middle position of the second gas introduction surface 6a. By providing this stepped portion 26, the volume of the flow path on the back side of the gas introduction flow path 25 is reduced.

  The second gas G2 flowing from the introduction port 17 flows through the gas introduction flow path 25, collides with the inclined inner wall surface 26a by the step portion 26 provided in the middle thereof, and is dispersed. Therefore, the dispersed second gas G2 is introduced to the entire second gas introduction surface 6a. In other words, the second gas G2 tends to be biased to the back side of the gas introduction channel 25 due to the characteristics of the gas flow. However, by causing the second gas G2 to collide with the step portion 26 in the middle of the flow path, it is easy to flow in the front side of the flow path, which is difficult to flow, and the gas is uniformly dispersed.

  The second gas discharge manifold 20 is integrated with the other side surface of the housing 12. The second gas discharge manifold 20 is provided with a discharge port 19 for discharging the second gas G2 introduced into the housing 12. The second gas discharge manifold 20 is provided with an internal space 27 so that a sufficiently large flow path to the discharge port 19 can be secured. By the second gas discharge manifold 20, the second gas discharge port 19 side and the second gas discharge surface 6 b of the storage case 6 face each other.

  Next, the basic gas flow of the first gas G1 and the second gas G2 in the humidifier 1 will be described. The first gas G1, which is a dry gas, is supplied from the inlet 13 of the first gas introduction manifold 14 and then flows through the flow passages of the hollow fiber membranes 4 constituting the hollow fiber membrane bundle 5 to discharge the first gas. It is discharged from the discharge port 15 of the manifold 16 for use.

  The second gas G2, which is a wet gas, is supplied from the introduction port 17 of the second gas introduction manifold 18, and then collides with the stepped portion 26 formed in the second gas introduction manifold 18, and is dispersed. The two gas introduction surfaces 6a are supplied as a uniform amount. The second gas G2 flows through the gaps between the hollow fiber membranes 4 of the hollow fiber membrane bundle 5 through the gas holes 8 formed in the second gas introduction surface 6a, and then the second gas discharge on the opposite side. The gas is discharged from each gas hole 9 formed in the surface 6b. The second gas G2 discharged from each gas hole 9 of the second gas discharge surface 6b is discharged from a discharge port 19 formed in the second gas discharge manifold 20.

  In the humidification field, the first gas G1 which is a dry dry gas flowing through the flow path of the hollow fiber membrane 4 and the second gas G2 which is a wet gas containing moisture flowing through the gap between the hollow fiber membranes 4 are in contact with each other. Moisture permeates from the outside to the inside of the hollow fiber membrane 4 due to the water vapor partial pressure difference inside and outside the hollow fiber membrane 4. Thereby, the water vapor in the wet gas permeates to the dry gas side and humidifies the first gas G1.

  As described above, the humidifying device 1 (specifically, the hollow fiber membrane module 2) of the present embodiment is shown in FIG. 5A in the environment of the normal operating temperature of the fuel cell system to which the humidifying device 1 is applied. ), The second gas G2 flows substantially uniformly in the storage case 6 by sewing the gaps between the hollow fiber membranes 4. In an environment of normal operating temperature, the arrangement of the hollow fiber membranes 4 is uniformly distributed in a cross section whose longitudinal direction is parallel to the axial direction of the storage case 6 and perpendicular to the longitudinal direction of the hollow fiber membrane 4. Yes.

  On the other hand, the humidifier 1 (specifically, the hollow fiber membrane module 2) of the present embodiment has a low environmental temperature (a temperature at which water condensed in the pores of the hollow fiber membrane 4 is frozen). As it approaches, as shown in FIG. 5 (b), the hollow fiber membrane 4 loosens as the storage case 6 contracts, thereby forming a gap (hereinafter referred to as “bypass path”) in the upper part of the storage case 6. Is done. This bypass path has a size larger than the interval between the hollow fiber membranes 4 in an environment of normal operating temperature. In other words, the storage case 6 of the present embodiment includes the storage case 6 in the first state in which the hollow fiber membranes 4 are linearly aligned in the axial direction and the hollow fiber membranes 4 are loosened. It functions as a setting means for setting the second state in which a bypass path having a dimension larger than the interval between the hollow fiber membranes 4 in the first state is set in response to the environmental temperature. In addition, the bypass passage passes through the storage case 6 in the flow direction of the second gas G <b> 2 in the storage case 6.

  In a low temperature environment, the water inside the pores of the hollow fiber membrane 4 freezes, so that the hollow fiber membrane 4 loses its elasticity and may be broken by receiving bending force due to the flow of the second gas G2. There is. However, according to the configuration of the present embodiment, a large amount of the second gas G2 flows through the bypass passage having a small passage resistance under the low temperature environment, and the amount of gas flowing through the gaps between the individual hollow fiber membranes 4 Decrease. Therefore, the bending displacement of the hollow fiber membrane 4 due to the flow of the second gas G2 is reduced, and breakage of the hollow fiber membrane 4 can be suppressed.

  Normally, in the hollow fiber membrane module 2, the hollow fiber membrane 4 is accommodated in the storage case 6 with an arbitrary filling rate. From the viewpoint of ease of sealing and reliability of the sealing portion, A filling rate of about 50% is employed. In this state, if the storage case 6 is contracted and the tension of the hollow fiber membrane 4 is loosened, each hollow fiber membrane 4 hangs down while drawing a suspension line due to the influence of gravity. The adjacent hollow fiber membranes 4 come into contact with each other at substantially the center in the longitudinal direction of the hollow fiber membrane 4, and eventually the dimensions of the bypass path are reduced even if the tension of the hollow fiber membrane 4 is loosened. It reaches a state where it does not grow any further. As a result of calculation through experiments and simulations, in the hollow fiber membrane module 2 with a filling rate of 50%, a bypass path having a height of 3% to 5% with respect to the dimension H in the height direction of the storage case 6 was formed. In some cases, the hollow fiber membranes 4 come into contact with each other.

  FIG. 6 is an explanatory diagram showing the relationship of the humidification amount to the first gas G1 with respect to the flow rate of the second gas G2. In the figure, a line L1 indicates data related to a conventional hollow fiber membrane module in which no bypass path is formed, and a line L2 indicates the hollow fiber membrane module 2 according to the present embodiment, specifically, the height of the bypass path. The data regarding the hollow fiber membrane module 2 in which the height dimension was set to 3% of the dimension H in the height direction of the storage case 6 is shown. Moreover, the line L3 has shown the data regarding the hollow fiber membrane module in the state in which the bypass path was always formed.

  As indicated by the line L1, the hollow fiber membrane module without a bypass always has a tendency that the humidification amount increases as the flow rate of the second gas G2 decreases. Thereby, it is understood that a constant gap is always ensured between the respective hollow fiber membranes, and the second gas G2 flows through the storage case while being in contact with the outer wall surface of the hollow fiber membranes evenly.

  On the other hand, as shown by the line L2, in the hollow fiber membrane module 2 constituting the bypass path of the present embodiment, when the flow rate of the second gas G2 is reduced, the humidification amount sharply decreases with a certain flow rate as a peak. Go. For example, the humidification amount at the flow rate a of the second gas G2 corresponding to the idling point of the fuel cell system is 30 or less when compared with the humidification amount of the hollow fiber membrane module having no bypass passage as 100. The second gas G2 has a strong force of flowing between the hollow fiber membranes 4 in a state where they hang down due to the action of gravity and are in contact with each other at a high flow rate. However, since the force of the second gas G2 decreases at a low flow rate, the flow resistance is low, and the flow to the bypass passage penetrating in the flow direction of the second gas G2 is dominant. To do. That is, the flow rate of the second gas G2 flowing through the gap between the hollow fiber membranes 4 is reduced. Therefore, it is understood that the force given from the second gas G2 to each hollow fiber membrane 4 is also reduced. That is, since the flow rate of the second gas G2 flowing through the gap between the hollow fiber membranes 4 is reduced by 70% or more, the flow rate of the second gas G2 is also reduced by 70% or more. In this case, the wind pressure applied to the hollow fiber membrane 4 is 9% or less of the case without the bypass.

  Such a result is a value sufficient to suppress breakage of the hollow fiber membrane 4 in a low temperature environment where the hollow fiber membrane 4 is frozen into the pores. Further, in a humidifier applied to a fuel cell system mounted on a moving body (for example, a vehicle), an idling operation is performed until all the components of the fuel cell system are thawed at the start after freezing. The above effects can be sufficiently obtained in the flow rate in the idling state.

  Further, in the present embodiment, the hollow fiber membrane module 2 of the humidifier 1 is such that when the environmental temperature is a normal operation temperature, the bypass path is not formed, and the bypass path is formed as the temperature approaches the low temperature. It has a configuration.

  As indicated by line L1 in FIG. 6, in a case where there is no bypass, the flow rate of the gas flowing around the hollow fiber membrane decreases as the flow rate of the second gas G2 decreases. Therefore, the amount of humidification increases because the gas contacts the membrane surface of the hollow fiber membrane for a longer time. On the other hand, as shown by the line L3 in FIG. 6, in the case where the bypass path is always present, the humidification is performed in the high flow rate region of the second gas G2 as compared with the case where there is no bypass path (line L1). The amount is low, and the humidification amount is drastically reduced in the low flow rate region. A humidifier applied to a fuel cell system mounted on a moving body (for example, a vehicle) is required to have higher humidification performance at a high load (that is, a high flow rate of the second gas G2), and a low load (that is, a high load). When the flow rate of the second gas G2 is low), a humidification performance that is suppressed to a level that does not cause excessive humidification is required. Therefore, it is necessary to have both the characteristics of the line L1 having no bypass path at high loads and the characteristics of the line L2 having bypass paths at low loads. The humidifying device 1 (hollow fiber membrane module 2) of the present embodiment can realize the above requirements by setting a bypass path in response to the environmental temperature. Therefore, in order to suppress the breakage of the hollow fiber membrane 4 when the hollow fiber membrane 4 is started from the frozen state, the humidification performance required during normal load operation cannot be satisfied simply by setting a bypass path. However, in this embodiment, breakage of the hollow fiber membrane at a low temperature can be suppressed without deteriorating the humidification performance.

As a method for forming the bypass path in response to the environmental temperature, the storage case 6 whose length changes in the longitudinal direction of the hollow fiber membrane 4 is adopted in the present embodiment. First, as shown in FIG. 7, after setting the length L of the hollow fiber membrane 4 and the inner width dimension W of the sealing portions at both ends of the storage case 6 in the upper limit of the operating temperature range, the operating temperature range is set. The details of the case material, the module length, and the module height H are determined so that the storage case 6 contracts so that the length L of the hollow fiber membrane 4 is equal to or less than the value represented by the following mathematical formula. To go.

  When the humidifier 1 having such a hollow fiber membrane module 2 is applied to a fuel cell system, the state inside the hollow fiber membrane module 2 after the operation of the fuel cell system is stopped changes as shown below. To do. First, immediately after the operation is stopped, the individual hollow fiber membranes 4 are held in the storage case 6 in a stretched state as in the operation, and a certain gap is secured between the hollow fiber membranes 4. ing. As the temperature gradually decreases, the length of the hollow fiber membrane 4 remains unchanged, and the length of the hollow fiber membrane 4 decreases due to the shrinkage of the material constituting the storage case 6.

  Due to the difference in length between the hollow fiber membrane 4 and the storage case 6 and the action of gravity, the individual hollow fiber membranes 4 slack in a suspended line shape, and there is a bypass path between the upper surface of the storage case 6. It begins to occur. As the temperature further decreases, the shrinkage of the storage case 6 further proceeds and the looseness of the hollow fiber membrane 4 also increases. However, the bypass path formed by this slack does not endlessly increase, but is formed within a predetermined maximum value range. This is because the gap held between the hollow fiber membranes 4 disappears, and when the adjacent hollow fiber membranes 4 come into contact with each other, no further slackening can occur.

  During such an environmental change, the condensed water of the second gas G2 attached to the outer wall of the hollow fiber membrane 4 starts to freeze, but the moisture retained inside the pores of the hollow fiber membrane 4 is frozen. Not. Therefore, the individual hollow fiber membranes 4 have not lost their flexibility, and the gaps formed by the slack of the hollow fiber membranes 4 as the storage case 6 contracts, that is, the bypass path is within the above-mentioned maximum value range. Can spread. When the temperature further decreases after the bypass path becomes maximum, the water inside the pores of the hollow fiber membrane 4 starts to freeze. Therefore, the hollow fiber membranes 4 in the storage case 6 are frozen and held while being in contact with each other while forming a bypass path.

  And at the time of starting of the fuel cell, since a low flow gas necessary for idling is first supplied, the burden on the hollow fiber membrane 4 is reduced by the above-described bypass effect, so that breakage of the hollow fiber is suppressed. Can do. Thereafter, when the thawing of the frozen portion proceeds and the expansion of the storage case 6 starts again, the tension of the hollow fiber membrane 4 is recovered inside the storage case, and a normal humidification operation can be obtained.

  Moreover, since the humidifier 1 of this embodiment employs a cross flow method, it is possible to obtain high humidification performance as compared to a parallel flow method in which the first gas G1 and the second gas G2 are parallel. .

  Furthermore, in this embodiment, since the bypass path is formed by utilizing the slackness of the hollow fiber membrane 4 due to gravity, the bypass path is formed above the storage case 6. Therefore, in this embodiment, the gas holes 8 and 9 provided in the side surfaces 6a and 6b of the storage case 6 are extended to the corners of the module case and are provided so as to reach the upper surface 6c of the storage case 6. Therefore, the second gas G2 can be efficiently guided to this bypass path.

  In the present embodiment, aluminum is used as a material constituting the storage case 6 that houses the hollow fiber membrane bundle 5. However, since the storage case 6 has a different linear expansion coefficient from the hollow fiber membrane 4 and the sealing member, there is a possibility that the boundary surface between the sealing member and the storage case 6 may peel off due to repeated temperature changes. Therefore, it is preferable to use a composite material storage case 6 that uses a plastic material for the sealing portion of the storage case 6 and uses a metal material such as aluminum only for the case body.

  When the individual hollow fiber membranes 4 are sealed and fixed to the storage case 6, the root portions of the hollow fiber membranes covered with the sealing member are inclined in advance in the slack direction of the hollow fiber membranes 4 in a low temperature environment. It is preferable to keep. In the process in which the hollow fiber membrane is loosened as the temperature is lowered, the entire hollow fiber membrane 4 is easily loosened equally in the same direction, and a desired bypass path can be obtained.

(Second Embodiment)
FIG. 8 is an explanatory view showing a state of the hollow fiber membrane 4 of the hollow fiber membrane module 2 constituting the humidifying device 1 according to the second embodiment. In the first embodiment described above, the bypass path is formed by contracting the storage case 6 as setting means for setting the bypass path in response to the environmental temperature. However, in the present embodiment, the storage case 6 is made of a material (for example, a plastic material) whose dimensions do not change regardless of the temperature environment, as in the past.

  Therefore, in this embodiment, the hollow fiber membrane bundle 5 is configured by assembling a plurality of hollow fiber membrane units configured by bundling a plurality of hollow fiber membranes with a binding yarn 10 around a rod-shaped temperature-sensitive member 7. Has been. The temperature-sensitive member 7 constituting the hollow fiber membrane unit is formed of a material that shrinks in a high-temperature environment (for example, a temperature-sensitive material such as polyisopropylacrylamide), that is, a material that extends in a low-temperature environment. In this case, in each hollow fiber membrane unit, the natural length L of each hollow fiber membrane 4 is not set equal to the total length of the storage case 6, but when loosened according to the bypass path to be formed. Its natural length is set. When the hollow fiber membrane bundle 5 is stored in the storage case 6, each hollow fiber membrane unit is stored in a slack state and sealed and fixed in accordance with a bypass path to be formed. On the other hand, in each hollow fiber membrane unit, the temperature sensitive member 7 is stored in the length in the temperature environment when performing the sealing operation, that is, in the environment where the temperature is lower than the operation temperature of the normal fuel cell system. It is set to correspond to the full length of the case.

  In such a configuration, in an environment of a normal operation temperature where the temperature is higher than that at the time of the sealing operation, the tension of the temperature sensitive member 7 located at the center of the hollow fiber membrane unit is increased, so that the surrounding hollow fiber membrane knitted together 4 is held in the storage case 6 so as to be lifted. In this case, gaps serving as gas passages are formed substantially evenly between the hollow fiber membranes 4.

  On the other hand, when the external temperature decreases, the temperature sensitive member 7 located at the center of the hollow fiber membrane unit is stretched. The hollow fiber membrane 4 surrounding the temperature sensitive member 7 is set to such a length as to have a slack in the storage case 6. Therefore, the temperature-sensitive member 7 is elongated and the hollow fiber membrane 4 is slackened. Then, after the temperature is gradually lowered and the hollow fiber membrane 4 is completely loosened and the bypass path is formed, when the temperature is further lowered, the water in the pores of the hollow fiber membrane 4 is frozen as described above.

  In this way, a plurality of hollow fiber membrane units in which the hollow fiber membrane 4 set to a length having a slack margin and the temperature-sensitive member 7 that contracts in a high-temperature environment are bundled are accommodated in the storage case 6. The hollow fiber membrane module 2 is configured.

In order to obtain such an action, the temperature-sensitive member 7 placed at the center of the hollow fiber membrane unit needs to have a thermal contraction coefficient α larger than a value represented by the following expression.

  According to this configuration, it is possible to obtain the same operations and effects as those in the first embodiment described above.

  When the rod-like temperature-sensitive member 7 is a solid member, the unit number of the hollow fiber membranes 4 in the opening cross section, that is, the total area of the flow passages of the hollow fiber membranes 4 is reduced, and the pressure loss may be increased. There is sex. Therefore, the increase in pressure loss can be suppressed by setting the shape of the temperature-sensitive member 7 to a hollow fiber shape.

(Third embodiment)
According to the present invention, the configuration of the setting unit that forms the bypass path is not limited to the above-described method. Various forms can be employed as long as the bypass path is formed in response to the temperature. Here, FIG. 9 and FIG. 10 are explanatory views showing other modified examples for forming a bypass path.

  For example, as shown in FIG. 9, a plurality of hollow fiber membranes 4 in the storage case 6 are divided into several large bundles, and the outer periphery of each bundle is made of a material that shrinks at a low temperature. A method of binding with the contracting member 11 is conceivable. In addition, as shown in FIG. 10, a pair of bimetal plates 11a each facing the surface with the higher low temperature shrinkage rate so as to divide the plurality of hollow fiber membranes 4 of the storage case 6 into several large bundles. A method of inserting can be considered.

  Thus, a bypass path can also be formed by adopting these methods alone for the hollow fiber membrane module 2. However, by applying an external force to the hollow fiber membrane 4, a bypass path is formed, so there is a concern that the burden on the hollow fiber membrane 4 will increase. Therefore, it is preferable to adopt these methods together with the method described in the first embodiment or the second embodiment. By this combined method, a bypass path can be more reliably formed without imposing a burden on the hollow fiber membrane 4, and breakage of the hollow fiber membrane 4 during freezing can be suppressed.

  The humidifier of the present invention can be applied not only to a fuel cell system, but also to various systems that humidify a dry gas by exchanging moisture between the dry gas and the wet gas.

The perspective view which shows typically the humidification apparatus 1 concerning 1st Embodiment. 1 is an exploded perspective view schematically showing the humidifying device 1 shown in FIG. The perspective view which shows typically the cross-sectional state of the hollow fiber membrane module 2 The perspective view which shows the hollow fiber membrane module 2 typically The perspective view which shows typically the internal state of the hollow fiber membrane module 2 Explanatory drawing which shows the relationship of the humidification amount to 1st gas G1 with respect to the flow volume of 2nd gas G2. Sectional drawing which shows hollow fiber membrane module 2 typically Explanatory drawing which shows the state of the hollow fiber membrane 4 of the hollow fiber membrane module 2 which comprises the humidification apparatus 1 concerning 2nd Embodiment. Explanatory drawing which shows the other modification which forms a bypass. Explanatory drawing which shows the other modification which forms a bypass.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Humidifier 2 ... Hollow fiber membrane module 3 ... Housing 4 ... Hollow fiber membrane 5 ... Hollow fiber membrane bundle 6 ... Storage case 7 ... Temperature sensitive member 8 ... Gas hole 9 ... Gas hole 10 ... Bundling thread 11 ... Contraction member DESCRIPTION OF SYMBOLS 11a ... Bimetal plate 12 ... Housing 14 ... First gas introduction manifold 16 ... First gas discharge manifold 18 ... Second gas introduction manifold 20 ... Second gas discharge manifold

Claims (7)

Between the first gas that flows through the flow path formed inside the hollow fiber membrane in the longitudinal direction and the second gas that flows outside the hollow fiber membrane in a direction intersecting the flow direction of the first gas. In a humidifier that exchanges moisture at
A hollow fiber membrane module that accommodates a hollow fiber membrane bundle in which a plurality of hollow fiber membranes are bundled in a cylindrical storage case having both ends opened;
A first gas inlet and outlet, a second gas inlet and outlet, and a housing for accommodating the hollow fiber membrane module therein.
The hollow fiber membrane module includes a first state in which each of the hollow fiber membranes is linearly aligned in the axial direction, and a slack in each of the hollow fiber membranes, thereby A humidifier further comprising setting means for setting a second state in which a bypass path, which is a gap having a size larger than the interval between the hollow fiber membranes in the state, is set in response to an environmental temperature. The storage case is formed with a plurality of gas holes on the surfaces of the housing facing the second gas introduction port and the discharge port, respectively.
2. The humidifier according to claim 1, wherein the bypass passage passes through the storage case in a flow direction of the second gas in the storage case.   The setting means is characterized in that the environmental temperature shifts from the first state to the second state as it approaches a low temperature at which water condensed in the pores of the hollow fiber membrane freezes. The humidifying device according to claim 1 or 2. The setting means includes the storage case formed of a temperature-sensitive member,
The humidification device according to claim 3, wherein the storage case contracts in the longitudinal direction of the hollow fiber membrane as the environmental temperature approaches the low temperature. The setting means is composed of a plurality of rod-shaped members each having sensitivity,
4. Each of the rod-shaped members is bundled together with a plurality of the hollow fiber membranes, and extends in the longitudinal direction of the hollow fiber membranes as the environmental temperature approaches the low temperature temperature. Or a humidifier described in 4. The setting means is composed of a plurality of net-like members that divide a plurality of hollow fiber membranes into a plurality of bundles and bind each of the divided hollow fiber membrane bundles at an outer peripheral portion,
6. The humidifier according to claim 3, wherein each of the net-like members contracts as the environmental temperature approaches the low temperature.   The said setting means is comprised by a pair of bimetal board which faced the surface where a low temperature shrinkage rate is higher each so that a several hollow fiber membrane may be divided | segmented into several bundles. The humidifier described in any one of 5 to 5.

Images