JP4644136B2 - Humidifier - Google Patents

Description

  The present invention relates to a humidifier used in a fuel cell system and the like, and more particularly, to a humidifier using a moisture permeable hollow fiber membrane.

  In recent years, research and development have been actively conducted on fuel cell systems mounted on fuel cell vehicles and the like. In a fuel cell system, power generation by an electrochemical reaction between hydrogen and air (oxygen) is performed in a fuel cell which is a main part of the fuel cell system. In particular, in a polymer electrolyte fuel cell or the like, a device for humidifying a gas (air or the like) supplied to the fuel cell is required due to its characteristics.

  And as the humidifier, the thing using the bundle | flux of a water-permeable hollow fiber membrane is common. In a humidifier using a hollow fiber membrane bundle, for example, moisture in the humid air (off gas) discharged from the fuel cell is moved to the air supplied to the fuel cell.

  In that case, one gas flows inside each hollow fiber membrane, and the other gas flows inside the hollow fiber membrane bundle and flows outside each hollow fiber membrane. At that time, the latter gas preferably flows through the entire hollow fiber membrane bundle. This is because if the unused portion of the hollow fiber membrane is large, efficient moisture transfer is not performed.

  Therefore, in Patent Document 1, for example, off-gas flowing inside the hollow fiber membrane bundle and flowing outside each hollow fiber membrane is introduced from the inner pipe and discharged to the outside from the discharge port provided on the side surface of the outer case. A technique relating to a humidifier that can increase the utilization efficiency of the hollow fiber membrane is disclosed.

In that case, in order to reduce the pressure loss due to off-gas inside the humidifying device, the opening area of the outlet on the side surface of the outer case is either single or plural in the axial direction of the humidifying device ( In the case of a plurality, the total value of the areas) needs to be increased to some extent.
JP 2004-6099 A (paragraph 0079, FIG. 3)

  However, in the technique of Patent Document 1, most of the off-gas that has entered the inside of the humidifier flows out to the outside from the upstream side of the discharge port on the side of the outer case, so the hollow fiber membrane further downstream is effectively used. There was a problem that was not.

  Then, this invention is made | formed in view of the said problem, and it aims at providing the humidification apparatus which can use the whole hollow fiber membrane effectively with sufficient balance.

In order to solve the above-mentioned problem, the humidifying device of the present invention according to claim 1 is a humidifying device in which moisture is transferred between the first gas and the second gas via a moisture-permeable hollow fiber membrane. An outer case having a tapered structure in which the inner peripheral surface is tapered toward the inner side of the cylinder toward the downstream side of the flow of the second gas, and inside the outer case, A core member that is concentrically arranged and has a taper structure in which a cross-sectional area becomes smaller toward the downstream side of the flow of the second gas, and a plurality of members that are housed in the outer case and are flow paths of the first gas A hollow fiber membrane bundle in which hollow fiber membranes are bundled, and the second gas provided in the outer case and having a flow path outside each hollow fiber membrane inside the hollow fiber membrane bundle. Are provided in the circumferential direction of the outer case, and the front in the outer case A plurality of discharge ports provided in the flow direction of the second gas, and the hollow fiber membrane bundle is disposed on an outer periphery of the core member, and the flow path of the second gas inside the hollow fiber membrane bundle Is characterized in that the cross-sectional area becomes smaller toward the downstream side of the flow of the second gas.

According to the humidifier of the present invention according to claim 1, since the cross-sectional area near the discharge port is smaller than the upstream cross-sectional area, the flow rate of the second gas (the flow rate in the axial direction of the humidifier. Near the outlet, it is faster than its upstream part. As a result, the second gas is increased in rectilinearity , and a plurality of second gases are provided in the circumferential direction of the outer case, and the second gas is discharged in a well-balanced manner from the entire outlets provided in the second gas flow direction in the outer case. Thus, the entire hollow fiber membrane is effectively used, that is, the humidification property is improved.
Moreover, by making the outer case have a tapered structure as described above, the cross-sectional area of the flow path of the second gas inside the hollow fiber membrane bundle can be reduced toward the downstream side of the flow of the second gas.
Moreover, by making the core member have a taper structure as described above, the flow of the second gas can be directed to the central portion in the axial direction of the humidifier, whereby the second gas from the back part of the discharge port can be directed. Can be promoted.

Humidifying device of the present invention according to claim 2, with a plurality of discharge ports, the opening area toward the downstream side of the second gas stream is increased.

According to the humidifier of the present invention according to claim 2 , the second gas can be discharged from each of the discharge ports in a well-balanced manner by changing the opening areas of the plurality of discharge ports as described above.

The humidifying device of the present invention according to claim 3 includes a plurality of inlets for allowing the second gas to flow into the flow path of the second gas, and the plurality of inlets are upstream of the flow of the second gas. The opening area becomes larger.

According to the humidifying device of the present invention according to claim 3 , the second gas can be introduced from each of the inlets in a well-balanced manner by changing the opening areas of the plurality of inlets as described above.

In the humidifying device of the present invention according to claim 4 , in the hollow fiber membrane bundle, the density of the hollow fiber membrane is lower as it is closer to the center of the outer case.

According to the humidifying device of the present invention according to claim 4 , a large amount of the second gas flows near the center of the humidifying device inside the hollow fiber membrane bundle, whereby the second gas from the inner part of the discharge port Emission can be promoted.

  According to the humidifier of the present invention, the entire hollow fiber membrane can be effectively used in a balanced manner.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an overall configuration diagram of the fuel cell system of the present embodiment. This fuel cell system is mounted on, for example, a fuel cell vehicle.

As shown in FIG. 1, the fuel cell system S includes a compressor 1, a humidifier 2, a fuel cell FC, and a hydrogen tank 3.
Actually, on-off valves are provided at appropriate positions in the piping, and the on-off valves and the compressor 1 are controlled by an ECU (Electronic Control Unit), but these are not shown.

The compressor 1 is a device that takes in air containing oxygen (first gas) from the outside and supplies the air to the humidifier 2.
The humidifier 2 moves the moisture (H ₂ O) of the humid off-gas (second gas) supplied from the cathode C of the fuel cell FC through the hollow fiber membrane HF (Hollow Fiber), so that the compressor 1 Is an apparatus for humidifying the air supplied from, and supplying the humidified air to the cathode C of the fuel cell FC. The details of the humidifier 2 will be described later with reference to FIGS.

  The fuel cell FC has a configuration in which a cation exchange type solid polymer electrolyte membrane (hereinafter referred to as “solid polymer membrane”) PEM (Polymer Electrolyte Membrane) is sandwiched between a cathode C and an anode A. In FIG. 1, the fuel cell FC is shown as a single cell configuration, but in practice, the fuel cell FC has a configuration in which a plurality of single cells are connected in series.

In the fuel cell FC, humidified air as an oxidant gas is supplied to the cathode C, and hydrogen (H ₂ ) as a fuel gas is supplied to the anode A, and electric power is generated by an electrochemical reaction between hydrogen and oxygen. .

Next, the configuration of the humidifier will be described with reference to FIG. 2 (see FIG. 1 as appropriate). FIG. 2 is a perspective view showing the appearance of the humidifying device.
As shown in FIG. 2, the outer case 31 of the humidifying device 2 has a constant outer diameter and a tapered inner diameter. In the humidifier 2, the air supplied from the compressor 1 enters the inside of the cap 27, and the hollow fiber membrane bundle 25 (a bundle of hollow fiber membranes HF arranged around the core member 26. The filling rate is 30 to 30. 70%) enters the inside of each hollow fiber membrane HF, flows through the inside, passes through the inside of the cap 28, and exits to the outside.

  Further, off-gas supplied from the cathode C of the fuel cell FC enters the inside of the humidifier 2 from the left side of FIG. 2 and is discharged from the outlets 21 to 24 provided on the right side of the side surface of the humidifier 2. It goes out and is collected by the manifold 29. A plurality of discharge ports 21 to 24 are provided in the circumferential direction of the humidifier 2.

  Here, the hollow fiber membrane HF is, for example, a thread-like membrane formed from a polymer material such as polyimide, and has a large number of fine pores with a diameter of several nanometers on its peripheral wall.

  Next, the internal structure of the humidifier will be described with reference to FIG. 3 (see FIGS. 1 and 2 as appropriate). FIG. 3 is a cross-sectional view taken along the line AA of the humidifier of FIG. The same components as those in FIG. 2 are denoted by the same reference numerals, and the description thereof is omitted as appropriate.

  As shown in FIG. 3, the humidifier 2 includes an inner case 32 having a taper structure in which the cross-sectional area decreases toward the right side in the axial direction. A core member 26 having a tapered structure whose sectional area decreases toward the right side of FIG. 3, that is, toward the downstream side of the off-gas flow, is inserted on the right side in the inner case 32. The inner case 32 on the left side of the core member 26 is provided with a plurality of inflow ports 35 through which off gas can pass. The off gas entering from the left side of FIG. 3 passes through the inflow port 35 and passes through the hollow fiber membrane bundle 25. It is designed to flow into the interior.

  The outer case 31 having a plurality of sets of discharge ports 21 to 24 (all the opening areas are the same) has its inner peripheral surface recessed toward the inside of the cylinder toward the right side of FIG. 3, that is, toward the downstream of the off-gas flow ( It has a tapered structure. Further, as it goes to the right in FIG. 3, the cross-sectional area (width of the vicinity) of the discharge ports 21 to 24 in the flow path of the off-gas inside the hollow fiber membrane bundle 25 (and outside the respective hollow fiber membranes HF). 3 is smaller than the upstream portion of the off-gas, that is, for example, the cross-sectional area in the vicinity of the off-gas inlet 35 (the width is about “a” in FIG. 3).

In FIG. 3, for ease of understanding, a> b is illustrated, but if the cross-sectional area of the off-gas flow path decreases toward the right in FIG. 3, The relationship may be a = b or a <b.
Specifically, first, as shown in FIG. 3, the length (diameter) from the center of the axis of the humidifier 2 to the hollow fiber membrane bundle 25 in the vicinity of the off-gas inlet 35 is R, the humidifier 2. Let r be the length (diameter) from the center of the shaft to the hollow fiber membrane bundle 25 in the vicinity of the discharge ports 21 to 24. Then, the cross-sectional area near the off-gas inlet 35 is π (R + a) ² −πR ² = π (2aR + a ² ), and the cross-sectional area near the outlets 21 to 24 is π (r + b) ² −πr ² = π ( 2br + ^{b 2)} to become.

Therefore, in order for the cross-sectional area of the off-gas flow path to decrease to the right in FIG. 3, π (2aR + a ² )> π (2br + b ² ), that is, (2aR + a ² )> (2br + b ² ) is necessary and sufficient. If the condition is satisfied and this relationship is satisfied, a ≦ b may be satisfied.

The potting part 33 and the potting part 34 are arranged between the hollow fiber membranes HF, between the hollow fiber membrane bundle 25 and the inner case 32, and so that only the hollow inside of the hollow fiber membrane HF is opened to the outside. It is a member that seals and fixes the membrane bundle 25 and the outer case 31.
With these configurations, the hollow fiber membrane bundle 25 approaches the center of the outer case 31 as it goes to the right in FIG.

Subsequently, the flow of air and off-gas will be described. The air supplied from the compressor 1 enters the inside of each hollow fiber membrane HF via the inside of the cap 27, flows through the inside, and is discharged as humidified air via the inside of the cap 28.
Further, the off-gas supplied from the cathode C of the fuel cell FC enters the inner case 32 from the left side of FIG. 3, passes through the inlet 35, and enters each hollow fiber membrane inside the hollow fiber membrane bundle 25. It passes outside the HF, is discharged from the discharge ports 21 to 24, and is collected by the manifold 29.
And air is humidified because the water | moisture content in a humid off gas moves to the air side via the hollow fiber membrane HF.

  Thus, in the flow path of the off gas inside the hollow fiber membrane bundle 25, the cross-sectional area in the vicinity of the discharge ports 21 to 24 is smaller than the upstream portion, so the off gas flow rate (the flow rate in the axial direction of the humidifier 2). The same applies hereinafter) in the vicinity of the discharge ports 21 to 24 is faster than the upstream thereof. As a result, the off-gas increases straightly and is discharged from each of the discharge ports 21 to 24 in a well-balanced manner without being discharged from the discharge port 21 in large amounts, so that the entire hollow fiber membrane (that is, the right end portion of the hollow fiber membrane bundle 25) Is also effectively used, that is, the humidification is improved.

  Moreover, by making the outer case 31 and the core member 26 have a tapered structure as shown in FIG. The flow of the off gas inside can be directed to the central portion in the axial direction of the humidifier 2. Thereby, discharge | emission of the off gas from the back part (discharge port 24 side) of the discharge ports 21-24 can be accelerated | stimulated, and off gas can be discharged | emitted from each of the discharge ports 21-24 with sufficient balance.

  In the present embodiment, the outer case 31 has a tapered structure that gradually increases in thickness toward the inside of the cylinder. However, the outer case 31 may have a uniform thickness and the entire humidifier 2 may be recessed. .

  Further, in the case where it is not possible to cope with it simply by improving the straightness by increasing the flow rate of the off-gas described above, as shown in FIG. 4, the discharge ports 21a to 24a are opened toward the downstream side of the off-gas flow. The area may be increased. If it does so, it will become difficult to discharge | emit offgas from the discharge port 21a more easily, and it will become easy to discharge | emit offgas from the discharge port 24a, that is, offgas can be discharged | emitted from each discharge port 21a-24a with sufficient balance.

  Furthermore, if the opening area of the off-gas inlets 35a to 35d is increased toward the upstream side of the off-gas flow (the left side in FIG. 4), the off-gas can easily flow into the hollow fiber membrane bundle 25 from the upstream side. Therefore, the entire hollow fiber membrane HF is effectively used, which is preferable.

  Then, next, the 1st modification of a humidification apparatus is demonstrated, referring FIG. 4 (refer suitably FIGS. 1-3). FIG. 4 is a cross-sectional view showing the internal structure of the humidifier according to the first modification. 4 corresponds to FIG. 3, and the same components as those in FIG. 3 are denoted by the same reference numerals, and the description thereof is omitted as appropriate.

The humidifying device 2a shown in FIG. 4 is different from the humidifying device 2 in FIG. 3 in that the discharge ports 21a to 24a have a larger opening area toward the downstream side of the off-gas flow, and the inner case 32a. That is, the opening areas of the inflow ports 35a to 35d are larger toward the upstream side of the off-gas flow.
The flow of air and off-gas in this case will be described. First, the flow of air supplied from the compressor 1 is the same as in the case of FIG.

The flow of off-gas supplied from the cathode C of the fuel cell FC is substantially the same as in FIG. 3, but differs in the following two points.
First, since the opening area of the inflow ports 35a to 35d becomes larger toward the upstream side of the off gas flow, the off gas easily flows from the inflow port 35a, and the off gas hardly flows from the inflow port 35d. That is, off-gas can be allowed to flow into the hollow fiber membrane bundle 25 from each of the inflow ports 35a to 35d in a balanced manner, and the entire hollow fiber membrane HF is effectively used.

  Further, since the opening areas of the discharge ports 21a to 24a are increased toward the downstream side of the flow of the off gas, the off gas is hardly discharged from the discharge port 21a, and the off gas is easily discharged from the discharge port 24a. That is, off-gas can be discharged in a balanced manner from the respective discharge ports 21a to 24a, and the entire hollow fiber membrane HF is effectively used.

  Next, a second modification of the humidifier will be described with reference to FIG. 5 (see FIGS. 1 to 4 as appropriate). FIG. 5 is a cross-sectional view showing the internal structure of the humidifying device of the second modified example. 5 is a diagram corresponding to FIG. 4, and the same components as those in FIG. 4 are denoted by the same reference numerals, and the description thereof is omitted as appropriate.

  The humidifying device 2b shown in FIG. 5 is different from the humidifying device 2a shown in FIG. 4 in that the outer case 31b has a flat structure instead of a tapered structure, and the inner case 32b and the core member 26a are shown in FIG. 5, that is, a taper structure in which the cross-sectional area increases toward the downstream side of the off-gas flow. As with the discharge ports 21a to 24a shown in FIG. 4, the opening areas of the discharge ports 21b to 24b are larger toward the downstream side of the off-gas flow. In addition, the opening areas of the inflow ports 35e to 35h are larger toward the upstream side of the off-gas flow, as in the case of the inflow ports 35a to 35d in FIG.

The flow of air and off-gas in this case will be described. First, the air supplied from the compressor 1 enters the inside of each hollow fiber membrane HF via the inside of the cap 27 and flows through the inside through the inside of the cap 28 as in the case of FIG. And discharged to the outside.
Further, the off-gas supplied from the cathode C of the fuel cell FC enters the inner case 32b via the cap 28, and further passes through the inlets 35e to 35h into the hollow fiber membrane bundle 25. It passes through, is discharged from the discharge ports 21 b to 24 b, and is collected by the manifold 29.

  Thus, the cross-sectional area (width is about "d" in the figure) near the discharge ports 21b to 24b is smaller than the cross-sectional area (width is about "c" in the figure) near the inflow ports 35e to 35h. The flow rate of the off gas is faster near the outlets 21b to 24b than near the inlets 35e to 35h. As a result, the off-gas increases straightly and is discharged from each of the discharge ports 21b to 24b in a well-balanced manner, and the entire hollow fiber membrane HF is effectively used.

  Further, in the humidifying device 2b of the second modified example, the core member 26a has a tapered structure as shown in FIG. 5, so that the flow of off gas can be reduced without taking the trouble of making the outer case 31b into a tapered structure. Regarding the path, the cross-sectional area in the vicinity of the discharge ports 21b to 24b can be made smaller than the cross-sectional area in the vicinity of the inflow ports 35e to 35h.

  In addition, in the humidifiers 2, 2 a, 2 b of FIGS. 3 to 5, the density (filling rate) of the hollow fiber membrane HF is closer to the axial center of the outer case 31, 31 a, 31 b in the hollow fiber membrane bundle 25. The structure can be low. By doing so, since the filling rate at the center is low, off-gas easily flows near the center and is easily discharged from the back (discharge ports 24, 24a, 24b), so that the hollow fiber membrane HF is effectively used. Will be.

This is the end of the description of the embodiments, but the aspects of the present invention are not limited to these. For example, although one set of outlets has been described as four, other numbers may be used. Moreover, although it was set as the structure which flows in off gas from the inner side of a humidifier, it is good also as a structure which flows in from the outer case side like the outer side of a humidifier, ie, an exhaust port.
Furthermore, various combinations and modifications are possible, such as combining the outer case 31a shown in FIG. 4 and the core member 26a shown in FIG. In addition, about a concrete structure, it can change suitably in the range which does not deviate from the main point of this invention.

It is a whole block diagram of the fuel cell system of this embodiment. It is a perspective view which shows the external appearance of a humidifier. It is AA sectional drawing of the humidification apparatus of FIG. It is sectional drawing which showed the internal structure of the humidification apparatus of the 1st modification. It is sectional drawing which showed the internal structure of the humidification apparatus of a 2nd modification.

Explanation of symbols

FC fuel cell HF hollow fiber membrane 1 compressor 2, 2a, 2b humidifier 3 hydrogen tank 21-24, 21a-24a, 21b-24b discharge port 25 hollow fiber membrane bundle 26, 26a core member 31, 31a, 31b outer case 35 35a-35h Inlet

Claims (4)

A humidifier in which moisture is transferred between the first gas and the second gas via a moisture-permeable hollow fiber membrane,
An outer case that is cylindrical and has a tapered structure in which the inner peripheral surface is recessed toward the inner side of the cylinder toward the downstream side of the flow of the second gas ;
Inside the outer case, a core member that is arranged concentrically with the outer case and has a tapered structure in which the cross-sectional area becomes smaller toward the downstream side of the flow of the second gas,
A hollow fiber membrane bundle that is housed in the outer case and bundles a plurality of hollow fiber membranes that are flow paths of the first gas;
The second gas provided in the outer case and having a flow path outside the hollow fiber membranes inside the hollow fiber membrane bundle is discharged to the outside of the outer case, and a plurality of the second gases are arranged in the circumferential direction of the outer case. And a plurality of discharge ports provided in the flow direction of the second gas in the outer case ,
The hollow fiber membrane bundle is disposed on the outer periphery of the core member,
Sectional area of the flow path of the second gas in the interior of the hollow fiber membrane bundle, humidifier, characterized in that downstream as small Kunar of flow of said second gas. The outlet of the previous SL humidifying apparatus according to claim 1, characterized in that the opening area toward the downstream side of the second gas flow is large. An inflow port for allowing the second gas to flow into the flow path of the second gas,
A plurality of the inflow ports are provided in the flow direction of the second gas in the outer case, and the plurality of the inflow ports have a larger opening area toward the upstream side of the flow of the second gas. The humidifying device according to claim 1 or 2 . The humidification device according to any one of claims 1 to 3 , wherein the hollow fiber membrane bundle has a lower density of the hollow fiber membrane as it is closer to a central portion of the outer case.

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