JP2002075421A - Humidifier for fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a humidifier for a fuel cell enabled to suitably use from the start of the fuel cell operation without separately installing a staring humidifier. SOLUTION: A plurality of hollow thread membranes are housed in the housing 31 of a hollow thread membrane module 21 of the humidifier. A supply air A is made flow inside a housing and outside the hollow thread membrane. A cooling water W is made flow at a part of the hollow thread membranes, and an exhaust air Ae exhausted from the fuel cell is made flow at another part of the hollow thread membranes. The supply air A is humidified due to the movement of the moisture contained in the exhaust air Ae into the supply air A. At the time that the moisture contained in the exhaust air Ae is not enough, like the starting time of the fuel cell, the supply air A is humidified by the cooling water W flowing at a part of the hollow thread membranes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a humidifier for a fuel cell, and more particularly to a humidifier for a fuel cell used for a fuel cell used in a fuel cell electric vehicle.

[0002]

2. Description of the Related Art In recent years, fuel cells have attracted attention as power sources for electric vehicles. As this fuel cell, there is a so-called polymer electrolyte fuel cell. In this polymer electrolyte fuel cell, a humidifier that exchanges the moisture of the off-gas, which is the wet gas discharged from the fuel cell, with the dry gas 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. .

A humidifying device using such a hollow fiber membrane is disclosed, for example, in Japanese Patent Application No. 2000-10971 by the present applicant. As shown in FIG. 7, the humidifier includes a hollow fiber membrane module 50. The hollow fiber membrane module 50 has a housing 51, in which a hollow fiber membrane bundle 52 formed by bundling a large number, for example, about 5,000 water-permeable hollow fiber membranes, is housed. Also, on one end side of the housing 51,
A plurality of supply air inlets 53 are formed, and a plurality of supply air outlets 54 are formed on the other end side. A discharge air inlet 55 for discharging a fuel cell (not shown) is formed at the other end of the housing 51, and a discharge air outlet 56 is formed at one end. The supply air A flowing from the supply air inlet 54 flows through the outside of the hollow fiber membrane in the housing 51, and the discharge air Ae flowing from the discharge air inlet 55 flows through the hollow fiber membrane. And the exhaust air A having a high moisture content
Water is exchanged between e and the supply air A having a low moisture content to humidify the supply air A.

[0004]

Incidentally, if the supply air supplied to the fuel cell in which this type of humidifier is used is dry, the fuel cell may be damaged due to the dry air. Therefore, a humidifying device used for a fuel cell is required to suitably humidify supply air not only when the fuel cell is used but also when the fuel cell is started. However, when starting the fuel cell, the exhaust air does not hold a sufficient amount of moisture because the fuel cell has no or little moisture. For this reason, in the conventional humidifying device, even if an attempt is made to humidify the supply air at the time of starting, sufficient moisture exchange cannot be performed with the exhaust air. Therefore, conventionally, a humidifier for starting has been separately provided. However, because of this humidifier for starting,
Since the entire system becomes large, there is a problem that it is contrary to a demand for an electric vehicle to be made compact.

Accordingly, an object of the present invention is to provide a humidifier for a fuel cell which can be suitably used from the start of the fuel cell without separately providing a humidifier for starting.

[0006]

Means for Solving the Problems According to the first aspect of the present invention which has solved the above problems, a plurality of hollow fiber membranes are housed in a housing, and the inside of the housing and the outside of the hollow fiber membrane are outside. The supply air supplied to the fuel cell is allowed to flow therethrough, and the exhaust air discharged from the fuel cell is caused to flow inside the hollow fiber membrane to exchange moisture between the supply air and the exhaust air. A humidifying device for a fuel cell that humidifies the supply air by providing a supply air inlet for introducing the supply air to the outside of the plurality of hollow fiber membranes and a supply air outlet for discharging the supply air. A discharge air inlet for introducing a part of the inside of the plurality of hollow fiber membranes and a discharge air outlet for discharging the discharge air, and a humidifying liquid for humidifying the supply air is supplied to the plurality of hollow fiber membranes. other A humidifying device for a fuel cell characterized by comprising a moisturizing liquid outlet portion minute humidifying liquid inlet for introducing the inside discharges the humidifying liquid.

According to the first aspect of the present invention, supply air flows outside the hollow fiber membranes, discharge air flows inside some of the hollow fiber membranes, and humidifies inside the other hollow fiber membranes. The liquid flows. Therefore, even when the exhaust air does not sufficiently contain moisture at the time of starting the fuel cell, the supply air can be sufficiently humidified by obtaining moisture from the humidifying liquid. In addition, by allowing the humidifying liquid to flow through the inside of the hollow fiber membrane, it is possible to collect and effectively use the water generated by the power generation of the fuel cell and to reduce the fuel due to insufficient humidification at the time of starting the fuel cell. It is also possible to prevent a decrease in battery performance. On the other hand, if the humidifying liquid is always supplied to the hollow fiber membrane, the humidifying performance will be excellent, but the humidifying liquid will always decrease, and sometimes an operation of replenishing the humidifying liquid will be required. Therefore, when the exhaust air contains sufficient moisture or when the supply air has a humidity of 80%
At the time of high humidification, such as when the humidification is sufficiently humidified, the supply of the humidification liquid to the hollow fiber membrane is stopped, and the humidification can be suppressed by reducing the amount of the humidification liquid by only humidifying the discharged air. .

Here, among the plurality of hollow fiber membranes, the number of hollow fiber membranes through which the humidifying liquid flows can be appropriately determined. The humidifying liquid can be passed through the hollow fiber membrane of the book.

The invention according to claim 2 is the humidifying device for a fuel cell according to claim 1, wherein the humidifying liquid is cooling water for the fuel cell.

In the invention according to claim 2, cooling water for cooling the fuel cell is used as the humidifying liquid. Therefore, there is no need to separately provide a tank or the like for storing the humidifying liquid, thereby contributing to downsizing of the entire fuel cell including the humidifying device. Further, by flowing the cooling water through the hollow fiber membrane humidifier, the cooling water warmed by the heat generated by the fuel cell can be cooled, so that the size of the radiator for cooling the cooling water can be reduced accordingly. . Further, the humidifier can be warmed while cooling the cooling water. For this reason, the supply air supplied to the humidifier can be warmed, so that the amount of moisture contained in the supply air can be increased. Further, since the discharged air can be heated, the condensed water in the discharged air can be vaporized, and the humidifying performance of the humidifier is improved, and the amount of recovered water is also increased.

According to a third aspect of the present invention, the hollow fiber membrane bundle is formed by bundling the plurality of hollow fiber membranes, and the hollow fiber membrane provided at the center of the hollow fiber membrane bundle is The fuel cell humidifier according to claim 1 or 2, wherein the humidifier is a hollow fiber membrane for a humidifier through which the humidifier flows.

In the invention according to claim 3, a hollow fiber membrane for water passage is provided at the center of the hollow fiber membrane bundle. The humidification efficiency with respect to the supply air is better when the humidification liquid is passed than when the discharge air is passed through the hollow fiber membrane. Therefore, by arranging the hollow fiber membrane for water passage having an excellent humidification efficiency at the center, the supply air can be efficiently humidified over the entire hollow fiber membrane bundle.

According to a fourth aspect of the present invention, there is provided a flow rate controlling means for controlling a supply amount of the humidifying liquid to the humidifying liquid hollow fiber membrane, wherein the flow rate controlling means is a humidification-related amount of air supplied to the fuel cell. The humidifying device for a fuel cell according to any one of claims 1 to 3, wherein the humidifying device is controlled according to the following.

According to a fourth aspect of the present invention, there is provided a flow rate controlling means for controlling a supply amount of the humidifying liquid to the humidifying liquid hollow fiber membrane, wherein the flow rate controlling means humidifies the supply air to the fuel cell. It is controlled according to the related quantity. For this reason,
The fuel cell can be started quickly, and the supply air supplied to the fuel cell is adjusted to a predetermined suitable range of humidity,
For example, it can be kept between 80 and 95%. Here, if the humidity of the supply air is less than 80%, humidification of the fuel cell membrane may be insufficient, and the membrane may be dried and damaged, which is not preferable. Conversely, when the humidity of the supply air exceeds 95%, the supply air is close to a saturated state, and water generated by power generation by the fuel cell is taken into the supply air, but the supply air is saturated. Since it is close to the state, the amount of water that can be taken in is small, and thus the generated water that has not been taken into the supply air may accumulate in the gas flow path of the fuel cell and block the gas flow path, which is not preferable. Here, the “humidification-related amount of the supplied gas” indicates the humidity and dew point of the supplied gas.

[0015]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is an overall configuration diagram of a fuel cell system including a humidifier for a fuel cell according to a first embodiment, and FIG. 2 is an explanatory diagram schematically illustrating a configuration of a fuel cell. The fuel cell system FCS shown in FIG. 1 is a power generation system including the fuel cell 1, an air supply device AS, a hydrogen supply device HS, and the like as a core.

First, as shown in FIG. 2, the fuel cell 1
It is divided into a cathode electrode side (oxygen electrode side) and an anode electrode side (hydrogen electrode side) with the electrolyte membrane 1c interposed therebetween, and an electrode containing a platinum-based catalyst is provided on each side, and the cathode electrode 1b
And an anode electrode 1d. Electrolyte membrane 1c
For example, a solid polymer membrane, for example, a perfluorocarbon sulfonic acid membrane which is a proton exchange membrane is used. This electrolyte membrane 1c has many proton exchange groups in a solid polymer,
By containing saturated water, it exhibits a low specific resistance of 20 Ω-proton or less at room temperature and functions as a proton conductive electrolyte. The catalyst included in the cathode electrode 1b is a catalyst that generates oxygen ions from oxygen, and the catalyst included in the anode electrode 1d is a catalyst that generates protons from hydrogen.

Outside the cathode electrode 1b, there is provided a cathode electrode side gas passage 1a through which supply air A as an oxidant gas flows through the cathode electrode 1b.
Outside the electrode d, an anode electrode-side gas passage 1e through which the supply hydrogen H as a fuel gas flows to the anode electrode 1d is provided. The inlet and outlet of the cathode-side gas passage 1a are connected to the air supply device AS, and the anode-side gas passage 1a is connected to the air supply device AS.
The inlet and outlet of e are connected to a hydrogen supply device HS. The configuration of the fuel cell 1 in FIG. 2 is schematically illustrated as one single cell, but the actual fuel cell 1 is configured as a stacked body in which about 200 single cells are stacked. . In addition, the fuel cell 1 has a cooling device (not shown) that cools the fuel cell 1 with cooling water because heat is generated by an electrochemical reaction during power generation.

In this fuel cell 1, the supply air A is passed through the cathode-side gas passage 1a, and the anode-side gas passage 1a.
When the supply hydrogen H is supplied to e, the hydrogen is ionized by the catalytic action at the anode electrode 1d to generate protons, and the generated protons move through the electrolyte membrane 1c and reach the cathode electrode 1b. Then, the protons that have reached the cathode electrode 1b immediately react with oxygen ions generated from oxygen of the supply air A in the presence of the catalyst to generate water. The supply air A containing the generated water and unused oxygen is discharged from the outlet on the cathode side of the fuel cell 1 as the discharge air Ae (the discharge air Ae contains a large amount of water). The hydrogen in the anode electrode 1d electrons e when ionized ^- but is produced, the generated electrons e ^- reaches the cathode electrode 1b via the external load M such as a motor.

Next, as shown in FIGS. 1 and 3, the humidifier AS has a humidifier 2 which is a humidifier for a fuel cell according to the present invention, an air cleaner 3, a compressor 4, and a pressure control device. It has a valve 5, between which supply air and exhaust air circulate. Humidifier 2
A temperature sensor T and a humidity sensor H are provided for detecting the temperature and humidity of the supply air A discharged from the air conditioner, respectively. On the other hand, as shown in FIG.
Is also provided with a heater 7, an on-off valve 8, and a pump 9, and constitutes a water circulation system. Between these, the humidifier 2 and the fuel cell 1, the cooling water of the fuel cell 1 serving as the humidifying liquid of the present invention circulates. In addition, an appropriate signal is output from the control device 6 to the compressor 4, the pressure control valve 5, the heater 7, the on-off valve 8, and the pump 9.

The humidifier 2 humidifies the air supplied from the air cleaner 3 and supplies the humidified air to the fuel cell 1. As the humidifier 2, a water-permeable membrane type in which two hollow fiber membrane modules are arranged in parallel or in series can be used. As shown in FIG. 4A, the hollow fiber membrane module 21 has a housing 31, in which a hollow fiber membrane bundle 32 composed of approximately 5000 hollow fiber membranes is housed. I have. The hollow fiber membrane constituting the hollow fiber membrane bundle 32 is a hollow fiber having a diameter of 1 to 2 mm and a length of several tens cm having a hollow passage. Further, the hollow fiber membrane has a large number of fine capillaries having a diameter of several nanometers (nanometers) extending from the inside to the outside, and in the capillaries, the vapor pressure is reduced and moisture condensation easily occurs. The condensed water is sucked out by capillary action and passes through the hollow fiber membrane.

The housing 31 has a hollow cylindrical shape with both ends open, and has eight supply air inlets 3 for introducing supply air into the housing 31 at one end in the longitudinal direction.
Are formed to be spaced apart in the circumferential direction. On the other end side of the housing 31 in the longitudinal direction, eight supply air outlets 34, 34 serving as supply air outlets are formed so as to be circumferentially separated. The one end side and the other end side of the hollow fiber membrane bundle 32 are potted to form potting portions 35 and 36. The other end of the housing 31 has a discharge air inlet 37 for inflowing the discharge air Ae, and the one end of the housing 31 has a discharge air outlet 38 for discharging the discharge air Ae. ing.

Further, as schematically shown in FIG. 5, the hollow fiber membrane bundle 32 is formed by bundling a plurality of hollow fiber membranes. These hollow fiber membranes are constituted by hollow fiber membranes 32a, 32a,... For ventilation, through which the exhaust air Ae flows, and hollow fiber membranes 32b, 32b,. In the present embodiment, the hollow fiber membrane bundle 32
Are about 5,000 hollow fiber membranes, and about 500 hollow fiber membranes for humidifying liquid 32b are provided.

As shown in FIG. 4B, supply air inlets 33, 33 formed at one end of the housing 31 are provided.
… Supply air A flows in from. The supply air A flowing into the housing 31 is introduced to the outside of the hollow fiber membrane in the housing 31 and flows through the outside of the hollow fiber membrane. Then, the air is discharged from supply air discharge ports 34 formed on the other end side of the housing 31. Also, the housing 31
A discharge air inlet 37 is formed at the other end of the humidifier, and a humidifying liquid inlet 37a into which the cooling liquid W is introduced is formed at the center. The exhaust air Ae introduced from the exhaust air inlet 37 is introduced into the ventilation hollow fiber membranes 32a shown in FIG.
a, 32a... Exhaust air A flowing through the hollow fiber membranes 32a for ventilation in the housing 31
e is discharged from a discharge air outlet 38 formed at one end of the housing 31. On the other hand, the cooling water W introduced into the housing 31 from the humidifying liquid inlet 37a is introduced into the humidifying liquid hollow fiber membranes 32b, 32b, and flows through the humidifying liquid hollow fiber membranes 32b, 32b. . The discharged air Ae and the cooling water W flowing through the humidifying liquid hollow fiber membranes 32b in the housing 31 are discharged from a humidifying liquid outlet 38a formed at the center of the discharged air outlet 38.

The humidifier 2 includes two hollow fiber membrane modules 21, a pipe for connecting the two hollow fiber membrane modules 21 and 21, and two hollow fiber membranes according to the flow rate and humidity of the supply air A. It has switching means such as an electromagnetic valve and an electromagnetic valve controller for switching and using the membrane module.

The humidifier 2 is supplied with the supply air A by the switching means.
When the flow rate of the supply air A is small, the switching drive is performed so that only one hollow fiber membrane module is used, and when the flow rate of the supply air A is large, the switching drive is performed so that both hollow fiber membrane modules are used. The switching drive is performed in this manner because the hollow fiber membrane module has the humidification characteristic that the humidification performance is reduced even if the flow rate of the supply air A and the discharge air Ae is too small or too large. The timing for driving the module switching means and the cooling water / discharge air switching means is determined by the control device 6 based on a detection signal from a flow rate sensor or a humidity sensor (not shown) or a temperature detection signal from the temperature sensor T.

The air cleaner 3 is composed of a filter (not shown) or the like, and filters air (supply air A) supplied to the cathode side of the fuel cell 1 to remove dust contained in the supply air A.

The compressor 4 is composed of a supercharger (a positive displacement compressor) (not shown) and a motor for driving the supercharger. The compressor 4 sends out supply air A used as an oxidizing gas in the fuel cell 1 to the humidifier 2. Supply. The supply air A is sent to the cathode side of the fuel cell 1 through the humidifier 2 by the output power of the compressor 4, and after passing through the fuel cell 1, becomes the exhaust air Ae and passes through the pressure control valve 5 to the humidifier 2. Sent to

The pressure control valve 5 includes a butterfly valve (not shown) and a stepping motor for driving the same, and reduces the pressure (discharge pressure) of the exhaust air Ae discharged from the compressor 4 to reduce the opening of the pressure control valve 5.・ Control by increasing.

The temperature sensor T comprises a thermistor or the like, detects the temperature of the supply air A supplied from the humidifier 2 at the inlet of the fuel cell 1 on the cathode side, and transmits a detection signal to the control device 6. The humidity sensor H is composed of a polymer film type humidity sensor or the like, detects the humidity of the supply air A at the cathode electrode side entrance of the fuel cell 1, and transmits a detection signal to the control device 6.

The heater 7 heats the cooling water W discharged from the fuel cell 1 before supplying it to the humidifier 2.
It is composed of a heater and the like. The heater 7 also has a role of quickly warming up the fuel cell 1 at the time of starting. The on-off valve 8 is for opening and closing the flow path of the cooling water W to the humidifier 2. By opening the on-off valve 8, the cooling water W flows through the humidifying liquid hollow fiber membranes 32b, and by closing the on-off valve 8, nothing flows through the humidifying liquid hollow fiber membranes 32b, 32b. There is no state. Further, the pump 9 is connected to the fuel cell 1
It operates when supplying the cooling water W from.

On the other hand, as shown in FIG.
S comprises a hydrogen gas cylinder 11, a regulator 12, a hydrogen circulation pump 13, a three-way valve 14, and the like.

The hydrogen gas cylinder 11 is composed of a high-pressure hydrogen container (not shown), and stores the supply hydrogen H introduced to the anode side of the fuel cell 1. The supply hydrogen H to be stored is pure hydrogen, and the pressure is 15 to 20 MPa (150 to 200 MPa).
kg / cm ² G). The hydrogen gas cylinder 11 may be of a hydrogen storage alloy type that contains a hydrogen storage alloy and stores hydrogen at a pressure of about ¹ MPa (10 kg / cm ² G).

The regulator 12 is a pressure control valve composed of a diaphragm, a pressure adjusting spring, and the like, not shown, for reducing the supply hydrogen H stored at a high pressure to a predetermined pressure so that it can be used at a constant pressure. When the reference pressure input to the diaphragm is set to the atmospheric pressure, the regulator 12 can reduce the pressure of the supply hydrogen H stored in the hydrogen gas cylinder 11 to near the atmospheric pressure.

The hydrogen circulating pump 13 is composed of an ejector (not shown) and the like, and utilizes the flow of the supply hydrogen H toward the anode electrode side of the fuel cell 1 to supply hydrogen after being used as fuel gas in the fuel cell 1. H, that is, fuel cell 1
The exhausted hydrogen He discharged from the anode electrode side and flowing through the three-way valve 14 is sucked and circulated.

The three-way valve 14 is composed of a flow path switch (not shown), and switches the flow path of the discharged hydrogen He to the discharge position and the circulation position. When the three-way valve 14 is at the discharge position, the discharged hydrogen He is discharged outside the system of the hydrogen supply device HS. When the three-way valve 14 is set at the circulation position, the discharged hydrogen He is guided to the hydrogen circulation pump 13.

The control device 6 includes a CPU (not shown),
The system includes a memory, an input / output interface, an A / D converter, a bus, and the like, controls the fuel cell system FCS in an integrated manner, and supplies supply air A supplied to the fuel cell 1.
To control the flow rate, temperature and humidity. The control device 6 receives the detection signal from the temperature sensor T as described above. Further, the control device 6 transmits control signals to the compressor 4 and the pressure control valve 5 as shown in FIG. Furthermore, FIG.
As shown in (1), the control signal is also transmitted to the heater 7, the on-off valve 8, and the pump 9.

Next, the operation and action of the humidifier according to the present invention will be described. First, the flow of air in the humidifier AS will be described in order. When the compressor 4 is operated, the supply air A is sucked from the outside air via the air cleaner 3. The sucked supply air A is sent to the humidifier 2 arranged on the downstream side. In the humidifier 2, FIG.
Flows through the inside of the housing 31 of the hollow fiber membrane module 21 of the humidifier 2 shown in FIG. 2 and the outside of the hollow fiber membrane constituting the hollow fiber membrane bundle 32 housed in the housing 31. At this time, when the cooling water W is passed through the humidifying liquid hollow fiber membranes 32b, 32b,.
a ... Water exchange is performed between the discharge air Ae flowing through the inside and the supply air A, and the supply air A is humidified, and at the same time, flows through the humidification liquid hollow fiber membranes 32b. Water is supplied from the cooling water W to the supply air A. When the cooling water W is not allowed to flow through the humidifying liquid hollow fiber membranes 32b, moisture exchange is performed only between the supply air A and the discharge air Ae.

Now, the cooling water W is applied to the humidifying liquid hollow fiber membrane 32b.
Comparing the case of passing through and the case of not passing,
When the cooling water W flows, the supply air A can be humidified at a higher rate. Therefore, when it is desired to increase the amount of humidification with respect to the supply air A during the operation of the fuel cell 1, the cooling water W may be passed through the humidification liquid hollow fiber membranes 32b. When the amount of humidification with respect to the supply air A is excessive or when the cooling water W is insufficient, the cooling water W should not be supplied to the humidifying liquid hollow fiber membranes 32b. Can be.

Alternatively, when starting the fuel cell 1, since the exhaust air Ae is not sufficiently humidified, the cooling water W may be passed through the humidifying liquid hollow fiber membranes 32b. By supplying the cooling water W to the humidifying liquid hollow fiber membranes 32b, the supply air A sufficiently humidified from the start of the fuel cell 1 can be supplied to the fuel cell 1.

When supplying the cooling water W to the humidifier 2,
The on-off valve 8 shown in FIG. 3 is opened and the pump 9 is driven. When the on-off valve 8 is closed, the cooling water W is not taken out of the fuel cell 1, and the cooling water W is not supplied to the humidifier 2. From here, on-off valve 8
And by driving the pump 9, the cooling water W discharged from the fuel cell 1 can be taken out and supplied to the humidifier 2 via the heater 7.

When the fuel cell 1 is started, the cooling water W
Is not warm. For this reason, even if the cooling water W is supplied to the humidifier 2, the humidifying efficiency of the supply air A is low with the cooled cooling water W. Therefore, when the cooling water W is in a cold state, such as when the fuel cell 1 is started, the heater 7 is operated to warm the cooling water W. The humidification efficiency in the humidifier 2 can be increased by warming the cooling water W. Thereafter, when the temperature of the fuel cell 1 rises and the cooling water W is warmed, the loss of energy can be reduced by stopping the heater 7. Whether or not the cooling water W is warmed is detected by measuring the temperature of the supply air A with the temperature sensor T.

The humidified supply air A is discharged from the humidifier 2 and supplied to the fuel cell 1 for power generation. Since the fuel cell 1 has generated water generated by power generation, the supply air A supplied into the fuel cell 1 absorbs the generated water, is humidified, and is discharged as exhaust air Ae. The exhaust air Ae discharged from the fuel cell 1 is sent out to the humidifier 2 and flows through the inside of the hollow fiber membrane constituting the hollow fiber membrane bundle 32 shown in FIG. Provided for exchange. The exhaust air Ae that has left the humidifier 2 is discharged into the atmosphere.

Subsequently, the humidifier AS shown in FIG. 1 includes a humidifier 2 for supplying air A supplied to the fuel cell 1,
Flow through the exhaust air Ae discharged from the fuel cell 1;
The supply air is humidified by exchanging the water contained in the discharge air Ae with the supply air. The operation at this time will be described. The hollow fiber membrane module 2 of the humidifier 2 shown in FIG.
The supply air A sent from the compressor 4 flows inside the housing 31 in FIG. 1 and outside the hollow fiber membranes constituting the hollow fiber membrane bundle 32. On the other hand, the exhaust air Ae sent from the pressure control valve 5 flows inside the hollow fiber membranes constituting the hollow fiber membrane bundle 32. Water is extracted from the exhaust air Ae passing through the hollow fiber membrane by capillary action in the hollow fiber membrane. The extracted water is condensed, passes through the capillary in the hollow fiber membrane, is discharged to the outside of the hollow fiber membrane, and the discharged water is absorbed by the supply air A. In this way, moisture is exchanged between the discharge air Ae and the supply air A, and the supply air A is humidified.

Next, a procedure for humidifying the supply air A at the time of starting the fuel cell 1 by the humidifier AS according to the present embodiment will be described with reference to FIG. FIG. 6 is a flowchart showing a procedure for humidifying the supply air A when the fuel cell 1 is started by the humidifier AS according to the present invention.

First, when the control is started and the control device 6 detects the start of the fuel cell (FC) 1 (S1), the on-off valve 8 is opened and the pump 9 is operated (S2). However, at this time, power generation in the fuel cell 1 has not been started. When the on-off valve 8 is opened and the pump 9 is operated, the cooling water W is supplied to the humidifying liquid hollow fiber membranes 32b among the hollow fiber membranes stored in the hollow fiber membrane module 21 of the humidifier 2.
Flows through. On the other hand, the compressor (S / C) 4 is operated to supply the supply air A to the humidifier 2 (S
3). When the supply of the supply air A to the humidifier 2 is started, the temperature of the supply air A discharged from the humidifier 2 is measured by the temperature sensor T, and a detection signal is output to the control device 6.

The control unit 6 determines whether the temperature t of the supply air A exceeds 60 ° C. based on the output detection signal (S4). As a result, when the temperature of the supply air A is 60 ° C. or less, the heater 7 is turned on (S
5) Perform temperature detection until the temperature exceeds 60 ° C. When the temperature t of the supply air A exceeds 60 ° C., the humidity h of the supply air A is measured by the humidity sensor H, and the detection signal is output to the control device 6. The control device 6 determines whether or not the humidity h of the supply air A has exceeded 80% based on the output detection signal (S5). As a result, the humidity h is 8
If it is 0% or less, humidity detection is performed until it exceeds 80%. Then, when the humidity h of the supply air A exceeds 80%, the power generation by the fuel cell 1 is started (S7). Here, the reason why the power generation is not started when the humidity h is 80% or less is that the supply air A is not sufficiently humidified. Therefore, when the power generation is started in this state, the fuel cell 1 is dried, and the fuel cell 1 is dried. This is because of the damages.

When the supply air A is sufficiently humidified and the humidity h becomes 80% or more and power generation is started by the fuel cell 1, it is detected whether or not the heater 7 is turned on (S8). As a result, if the heater 7 is ON,
The heater is turned off (S9). Then, the heater 7 is turned off.
F, the on-off valve 8 is closed and the humidifying liquid hollow fiber membrane 32 is closed.
b, 32b... is stopped (S
10). This is because when the power generation of the fuel cell 1 starts, the supply air A can be sufficiently humidified by the exhaust air Ae discharged from the fuel cell 1. The pump 9 is stopped when the fuel cell 1 is stopped.

Thus, the humidifying operation of the supply air A by the humidifying device AS at the time of starting the fuel cell 1 is stopped. After the operation of the fuel cell 1, the air A discharged from the fuel cell 1
By performing a moisture exchange between e and the supply air A,
The supply air A can be humidified.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. For example, while power is being generated by the fuel cell 1, the humidity of the supply air A is detected by the humidity sensor H, and when the humidity of the supply air A becomes lower than a predetermined humidity, the hollow fiber for humidifying liquid is used. The cooling water W may be supplied to the membranes 32b. In the above embodiment, when the cooling water W is not allowed to flow through the humidifying liquid hollow fiber membranes 32b, 32b, nothing is allowed to flow. It is also possible to adopt a mode of flowing. In this case, the humidifying liquid hollow fiber membranes 32b, 32b... Can switch between the humidifying liquid such as the cooling water W and the discharged air Ae.

Further, although the cooling water W for cooling the fuel cell 1 is used as the humidifying liquid, water for humidifying the supply air A or other liquids may be used. On the other hand,
The hollow fiber membrane 32 for humidifying liquid is provided at the center of the hollow fiber membrane bundle 32.
Although b, 32b,... are set, they may be set not only at the center but also at positions near the outer periphery. In addition, the hollow fiber membrane 3 for humidifying liquid is used.
2b, 32b... Is about 10% of the entire hollow fiber membrane, but may be set to an appropriate amount such as, for example, 20% or 30%. Further, although the heater 7 is provided to suitably humidify the supply air A when the fuel cell 1 is started, a mode without the heater may be adopted.

Further, a water amount detecting means for detecting the amount of cooling water of the fuel cell 1 is provided, and when the amount of cooling water becomes small, water is supplied to the exhaust air discharged from the fuel cell. You can also. With such a configuration, it is possible to effectively use the water generated by the fuel cell that has been conventionally discharged, and to prevent a decrease in the performance of the fuel cell due to a shortage of the cooling water.

[0052]

As described above, claim 1 of the present invention
According to the invention, the supply air can be sufficiently humidified even when the exhaust air does not sufficiently contain water at the time of starting the fuel cell. Therefore, the fuel cell can be suitably used from the start of the fuel cell without separately providing a humidifier for the start.

According to the second aspect of the present invention, the cooling water for cooling the fuel cell can be suitably used. Also,
Cooling water that has been heated by the heat generated by the fuel cell can be cooled,
The size of the radiator for cooling the cooling water can be reduced. Further, the supply air and the discharge air supplied to the humidifier can be warmed, so that the humidification performance of the humidifier is improved and the water recovery amount is also increased.

According to the third aspect of the present invention, the water supply hollow fiber membrane for improving the humidification efficiency is disposed at the center, so that the supply air is efficiently humidified over the entire hollow fiber membrane bundle. be able to.

According to the fourth aspect of the present invention, the fuel cell can be started quickly, and the supply air supplied to the fuel cell is adjusted to a predetermined suitable range of humidity, for example, 8%.
It can be kept between 0 and 95%.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a fuel cell system including a humidifier.

FIG. 2 is an explanatory diagram schematically illustrating a configuration of a fuel cell.

FIG. 3 is a configuration diagram of a humidifier including a water circulation system.

FIG. 4A is a perspective view of a hollow fiber membrane module included in a humidifier, and FIG. 4B is a side sectional view thereof.

FIG. 5 is a schematic longitudinal sectional view of a hollow fiber membrane module.

FIG. 6 is a flowchart showing a procedure for humidifying supply air when the fuel cell is started by the humidifier according to the present invention.

FIG. 7 is a side sectional view of a conventional humidifier.

[Description of Signs] 1 Fuel cell 2 Humidifier (humidifier for fuel cell) 3 Air cleaner 4 Compressor 5 Pressure control valve 6 Control device 7 Heater 8 Open / close valve 9 Pump 21 Hollow fiber membrane module 31 Housing 32 Hollow fiber membrane bundle 32a Ventilation Hollow fiber membrane (hollow fiber membrane) for water 32b hollow fiber membrane for water passage (hollow fiber membrane) 37a humidifying liquid inlet 37b humidifying liquid outlet A supply air Ae discharge air AS humidifier FCS fuel cell system HS hydrogen supply device H humidity Sensor T Temperature sensor W Cooling water (humidifying liquid)

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F24F 6/00 F24F 6/00 B 6/04 6/04 (72) Inventor Tomohiro Tsuchiya Central Wako, Saitama 1-4-1 in Honda R & D Co., Ltd. (72) Inventor Seiji Tonegawa 1-4-1 Chuo, Wako-shi, Saitama F-term in Honda R & D Co., Ltd. F-term (reference) 3L055 AA10 BA01 DA05 4D006 GA41 HA02 KA67 KE01P KE01Q KE16P KE16Q KE30P KE30Q MA01 MC05 MC38 MC74 PB17 PB18 PB65 PB66 PC72 PC80 5H027 AA06 BC19

Claims (4)

[Claims] 1. A plurality of hollow fiber membranes are housed in a housing, and supply air supplied to a fuel cell is passed inside the housing and outside the hollow fiber membranes, and inside the hollow fiber membranes. A fuel cell humidifier for humidifying the supply air by passing exhaust air discharged from a fuel cell and exchanging moisture between the supply air and the exhaust air, wherein the supply air is supplied to the plurality of hollows. A supply air inlet for introducing outside the fiber membrane and a supply air outlet for discharging supply air, and an exhaust air inlet and exhaust air for introducing the exhaust air inside a part of the plurality of hollow fiber membranes. A humidifying liquid inlet for introducing a humidifying liquid for humidifying the supply air into another portion of the plurality of hollow fiber membranes, and a humidifying liquid outlet for discharging the humidifying liquid. Department Fuel cell humidifier, characterized in that to obtain. 2. The humidifying device for a fuel cell according to claim 1, wherein the humidifying liquid is cooling water for the fuel cell. 3. The hollow fiber membrane bundle is formed by bundling the plurality of hollow fiber membranes, and the humidifying liquid flows through the hollow fiber membrane provided at the center of the hollow fiber membrane bundle. 3. The humidifier for a fuel cell according to claim 1, wherein the humidifier is a hollow fiber membrane for a humidifier. 4. A flow rate control means for controlling a supply amount of the humidification liquid to the humidification liquid hollow fiber membrane, wherein the flow rate control means is controlled in accordance with a humidification-related amount of air supplied to the fuel cell. The humidifying device for a fuel cell according to any one of claims 1 to 3, wherein