JP2002110205A - Cooling device for fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling device for a fuel cell, capable of preventing large deterioration of the ion exchange resin in an ion exchange device and supplying a cooling liquid having a temperature favorable for the fuel cell by two temperature control by one cooling system. SOLUTION: A second heat exchanger 15 is arranged in parallel with the inlet side and the outlet side of a first cooling liquid in the fuel cell FC. The first cooling liquid discharged from a first heat exchanger 3 passes through the second heat exchanger 15, a radiator 16, and the ion exchange device 14 in this order and flows into the second heat exchanger 15 again. In the second heat exchanger 15, the first cooling liquid discharged from the first heat exchanger 3 and the first cooling liquid discharged from the ion exchange device 14 flow opposingly, and are self-heat exchanged between them.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell cooling device capable of suitably cooling a fuel cell.

[0002]

2. Description of the Related Art In recent years, various electric vehicles equipped with a traveling motor instead of an engine have been developed. And
One example of this type of electric vehicle is PEMFC
(Proton Exchange Membrane Fuel Cell)
It is called "PEM fuel cell". The development of a fuel cell vehicle equipped with a) as a power source for a traveling motor is rapidly progressing.

[0003] This PEM fuel cell is configured as a stack having a structure in which a number of cells as power generation units are stacked. Each cell has a structure in which a membrane / electrode assembly, which is abbreviated as MEA (Membrane Electrode Assembly), is sandwiched between an anode separator having a hydrogen supply passage and a cathode separator having an oxygen supply passage. The MEA is configured such that an anode-side electrode catalyst layer and a gas diffusion layer are sequentially laminated on one side of a hydrogen ion exchange membrane, and a cathode-side electrode catalyst layer and a gas diffusion layer are sequentially laminated on another side of the hydrogen ion exchange membrane. Have been.

[0004] In such a PEM fuel cell, hydrogen ions pass from the anode side to the cathode side through the hydrogen ion exchange membrane in the wet state of the MEA.
An electromotive force of about V is generated. In the PEM fuel cell, the most stable output state can be obtained in a temperature environment of, for example, about 75 to 85 ° C., and the circuit configuration is configured to drive the traveling motor from the output current control device via the drive unit. Have been.

[0005] A fuel cell vehicle equipped with a fuel cell such as a PEM fuel cell is provided with a cooling device for maintaining the fuel cell in a predetermined appropriate temperature range. Among the cooling devices, there is a cooling device described in Japanese Patent Application No. 2000-155519 by the present applicant in order to prevent a liquid junction of a fuel cell. FIG. 4 shows a schematic configuration of the cooling device. The cooling device 50 is provided in the primary cooling system that cools the fuel cell FC by circulating and supplying a coolant to the fuel cell FC.
2 capable of exchanging heat between the primary circulation channel 51 and the primary cooling system
Secondary circulation flow path 5 through which the secondary coolant in the secondary cooling system circulates
2 is provided.

[0006] The primary circulation channel 51 is provided with a primary pump 53 for flowing an insulating primary coolant into the primary circulation channel 51. Further, a temperature controller 54 composed of a thermostat, for example, and an ion exchanger 55 for removing various ions such as metal ions contained in the primary coolant are provided. Further, the secondary circulation channel 52 includes a secondary pump 56 for flowing the secondary coolant into the secondary circulation channel 52 and a radiator 57 for cooling the secondary coolant. Further, a heat exchanger 58 through which the primary circulation flow path 51 and the secondary circulation flow path 52 pass is provided. In this heat exchanger 58, the primary cooling liquid discharged from the fuel cell FC by the secondary cooling liquid is provided. To cool.

[0007]

By the way, the ion exchanger 55 provided in the primary circulation channel 51 can adsorb when the temperature of the primary coolant is high, for example, 60 ° C. or more. There is a problem that the amount of ions is significantly reduced.
Further, when the temperature of the primary coolant is high, there is a problem that the ion exchange resin provided in the ion exchanger is greatly deteriorated.

On the other hand, the PEM fuel cell has a capacity of 75%.
Since the most stable output state can be obtained in a temperature environment of about 85 ° C. to about 85 ° C., when cooling the PEM type fuel cell with the cooling device 50, it is necessary to supply the primary cooling liquid of about 70 ° C. to the PEM type fuel cell. desirable. As described above, since the temperature required for the primary coolant flowing through the ion exchanger 55 is different from the temperature required for the primary coolant flowing through the fuel cell, separate temperature management is required in the same primary cooling system. Can be To solve this problem, it is conceivable that the primary cooling liquid to be supplied to the fuel cell and the primary cooling liquid to be supplied to the fuel cell are constituted by different cooling systems. This also led to an increase in production costs.

Therefore, an object of the present invention is to prevent two kinds of temperature control by one cooling system, thereby preventing a severe deterioration of an ion exchange resin in an ion exchanger and cooling a temperature suitable for a fuel cell. An object of the present invention is to provide a fuel cell cooling device that can supply a liquid.

[0010]

According to the present invention, there is provided a circulating pump for circulating a coolant in a cooling system for circulating and supplying a coolant to a fuel cell to cool the fuel cell; The first to cool the coolant discharged from the battery
A heat exchanger, an ion exchanger using an ion exchange resin for removing ions in the coolant, a radiator for cooling the coolant, and a second heat exchanger for self-exchanging the coolant. Wherein the second heat exchanger is disposed in parallel with the inlet and outlet sides of the coolant in the fuel cell, and the coolant discharged from the first heat exchanger is (2) The heat exchanger, the radiator, and the ion exchanger flow in this order, and the primary coolant discharged from the ion exchanger is supplied to the second heat exchanger. In the second heat exchanger, the coolant discharged from the first heat exchanger and the coolant discharged from the ion exchanger flow in opposition to each other, and are discharged from the first heat exchanger. The cooled liquid and the cooled liquid discharged from the ion exchanger. By performing the self-heat exchange between the liquids, the cooling liquid discharged from the first heat exchanger is cooled, and the temperature of the cooling liquid discharged from the ion exchanger is raised. It is a fuel cell cooling device characterized by the following.

In the present invention, the coolant discharged from the first heat exchanger is supplied to the radiator through the second heat exchanger. After cooling the coolant in this radiator,
The heat is supplied to the second heat exchanger and self-exchanges with the coolant discharged from the first heat exchanger. By the self-heat exchange in the coolant, the coolant discharged from the first heat exchanger is cooled, and the temperature of the coolant discharged from the ion exchanger is raised. For this reason, the temperature of the coolant finally discharged from the second heat exchanger is not greatly changed than the temperature between the first heat exchanger and the second heat exchanger, and the outlet side of the radiator is not changed. Temperature between the first heat exchanger and the second heat exchanger can be reduced. Here, the second heat exchanger is arranged in parallel with the inlet and outlet of the coolant in the fuel cell, and there is no significant change in temperature between the inlet and outlet of the second heat exchanger. Therefore, the temperature of the coolant supplied to the fuel cell can be easily controlled without being greatly affected by the presence of the second heat exchanger. Further, since the ion exchanger is disposed between the outlet side of the radiator and the second heat exchanger, the temperature of the primary coolant supplied to the ion exchanger can be adjusted by adjusting the heat radiation of the radiator. It can be lowered to a suitable temperature. Therefore, since two temperatures can be managed by one cooling system, severe deterioration of the ion exchange resin in the ion exchanger can be prevented, and a coolant having a suitable temperature can be supplied to the fuel cell.

[0012]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a circuit diagram of a cooling device for a fuel cell according to an embodiment of the present invention.
FIG. 2 is a partial sectional view showing a cell structure of the fuel cell shown in FIG.

[0013] The fuel cell cooling device M according to the present embodiment.
As shown in FIG. 1, the primary cooling systems 1 and 2 which are the cooling system of the present invention in which the primary cooling liquid for cooling the fuel cell FC circulates.
It has a secondary cooling system 2, and these primary cooling system 1 and secondary cooling system 2 are connected via a first heat exchanger 3. The first heat exchanger 3 cools the primary coolant discharged from the fuel cell FC.

A primary circulation channel 11 is formed in the primary cooling system 1. The primary cooling system 1 includes a primary circulation pump 12 that circulates the primary coolant in the primary circulation channel 11 and a thermostat valve having, for example, a three-way valve, and is capable of adjusting the temperature of the primary coolant. Temperature controller 13 and ion exchanger 14 for removing ions such as metal ions in the primary coolant
It has. Also, on the upstream side of the ion exchanger 14,
A second heat exchanger 15 for self-exchanging the primary coolant before and after passing through the ion exchanger 14 and a radiator 16 for cooling the primary coolant are provided.

The primary circulation flow path 11 includes a primary circulation pump 12
To the first heat exchanger 3 and the coolant passage C12 of the fuel cell FC.
It is constituted mainly by a circulation flow path of the primary coolant which returns to the primary circulation pump 12 after passing through FIG. A temperature controller 13 is provided in a flow path between the first heat exchanger 3 and the primary circulation pump 12.
Is provided, and a bypass flow passage 11A branched from the temperature controller 13 is provided in parallel with the first heat exchanger 3. The temperature controller 13 is a well-known thermostat, and has a member that expands due to heat. With this member, the cross-sectional area of the warm primary coolant flowing from the bypass flow passage 11A and the cross-sectional area of the cold primary coolant flowing from the first heat exchanger 3 are changed, and the warm primary coolant flowing from the bypass flow passage 11A is changed. The inflow ratio of the secondary coolant and the cold primary coolant flowing from the first heat exchanger 3 is adjusted. Then, the primary coolant adjusted to a temperature of about 70 ° C. is discharged.

In the primary circulation flow path 11, a communication path 11B branched from a flow path between the primary circulation pump 12 and the fuel cell FC is provided in parallel with the bypass flow path 11A. In the communication path 11B, the second heat exchanger 15, the radiator 16,
And an ion exchanger 14 in this order from the upstream side. Therefore, the coolant discharged from the first heat exchanger 3 flows through the second heat exchanger 15, the radiator 16, and the ion exchanger 14 in this order, and the primary coolant discharged from the ion exchanger 14 Is supplied to the second heat exchanger 15 again. The second heat exchanger 15 is arranged in parallel with the inlet side and the outlet side of the primary coolant in the fuel cell FC, and the second heat exchanger 15 discharges from the first heat exchanger 3. The primary coolant thus discharged and the primary coolant discharged from the ion exchanger flow in opposition to each other. Then, self-heat exchange is performed between the primary coolant discharged from the first heat exchanger 3 and the primary coolant discharged from the ion exchanger 14. By this self-heat exchange, the coolant discharged from the first heat exchanger is cooled, and the temperature of the coolant discharged from the ion exchanger is raised. The radiator 16 is, for example, an air-cooled type that cools the primary coolant by contacting with outside air (not shown). The radiator 16 cools the primary coolant discharged from the second heat exchanger 15 before sending it to the ion exchanger 14. The ion exchanger 14 includes an ion exchange resin (not shown), and adsorbs and removes various ions such as metal ions eluted in the primary circulation channel 11.

The primary circulation passage 11 including the bypass passage 11A and the communication passage 11B is accommodated in a fuel cell box (not shown) together with the first heat exchanger 3. Also, 1
The secondary circulation channel 11 is made of an appropriate material from which ions are hardly eluted, for example, an insulating material such as a stainless steel tube or a synthetic resin tube, in order to prevent a liquid junction phenomenon of the fuel cell FC. In order to prevent the liquid junction phenomenon, an insulating refrigerant is used as the primary cooling liquid. As the insulating refrigerant, it is preferable to use pure water or a mixture of pure water and an ethylene glycol-based liquid whose electric conductivity is kept low, but it is also possible to use insulating oil.

On the other hand, the secondary cooling system 2 has a secondary circulation passage 21.
Are formed. In the secondary circulation channel 21, a secondary circulation pump 22 that circulates the secondary coolant into the secondary circulation channel 21
And a radiator 23 for air cooling the secondary coolant.

The secondary circulating flow path 21 is supplied with a secondary coolant from a secondary circulating pump 22 to a first heat exchanger 3 and a radiator 23.
To return to the secondary circulation pump 22. The radiator 23 is an air-cooled radiator provided with an electric cooling fan (not shown). Further, similarly to the primary circulation channel 11, the secondary circulation channel 21 is made of an appropriate material that does not easily elute ions, such as a stainless steel pipe or a synthetic resin pipe, in order to prevent a liquid junction phenomenon of the fuel cell FC. It is made of material. As the secondary cooling liquid, an insulating refrigerant such as the above-described pure water or a mixture of pure water and an ethylene glycol-based liquid is used to prevent the liquid junction phenomenon, similarly to the primary cooling liquid.

The fuel cell FC is a PEM type fuel cell having a structure in which a number of cells as power generation units are stacked. For example, the most stable output state can be obtained in a temperature environment of about 75 to 85 ° C. Here, as shown in FIG.
Each cell C constituting the fuel cell FC includes a membrane having a seal C5 between a cathode separator C2 having an oxygen supply passage C1 on the inner surface side and an anode separator C4 having a hydrogen supply passage C3 on the inner surface side. Electrode assembly (MEA) C
6 is provided. In the membrane / electrode assembly C6, a cathode-side electrode catalyst layer C8 and a gas diffusion layer C9 are sequentially laminated on one side of a hydrogen-ion exchange membrane C7, and the anode-side electrode catalyst layer C9 is formed on the other side of the hydrogen-ion exchange membrane C7.
10 and a gas diffusion layer C11 are sequentially laminated. Further, a coolant passage C12 is formed on the outer surface side of the anode-side separator C4.

In the cooling device for a fuel cell according to the present embodiment configured as described above, the primary coolant and the secondary coolant are
The secondary coolant circulates through the primary circulation channel 11 and the secondary circulation channel 21, respectively. Here, when the temperature of the fuel cell FC in which the primary coolant passing through the temperature regulator 13 of the primary circulation channel 11 is low is low, the temperature regulator 13 is connected to the first heat exchanger 3.
The primary coolant is supplied from the primary circulation pump 12 to the primary circulation pump 12 via the bypass passage 11A, the temperature controller 13, and the coolant passage C12 of the fuel cell FC in order to close the flow path on the outlet side of the fuel cell FC. Circulates to Then, the primary coolant circulating around the first heat exchanger 3 absorbs heat while passing through the coolant passage C12 of the fuel cell FC and gradually rises in temperature, thereby warming up the fuel cell FC. I do.

When the temperature of the primary coolant passing through the temperature controller 13 in the primary circulation channel 11 rises and the fuel cell FC is completely warmed up, the temperature controller 13 flows in from the bypass channel 11A. The inflow ratio of the primary coolant and the primary coolant flowing from the first heat exchanger 3 is adjusted to, for example, 70 ° C. The primary coolant whose temperature has been adjusted in this way passes through the coolant channel C12 of the fuel cell FC, and absorbs heat in the process to cool the fuel cell FC. Then, the primary cooling liquid that has cooled the fuel cell FC exchanges heat with the secondary cooling liquid in the secondary circulation channel 21 again by the first heat exchanger 3 to radiate heat and be cooled.

On the other hand, the secondary coolant flows from the secondary circulation pump 22 through the heat exchanger 3 to the radiator 23 in the secondary circulation channel 21, flows out of the radiator 23, and flows out of the secondary circulation pump 22. Circulates to The secondary coolant exchanges heat with the primary coolant in the primary circulation channel 11 in the primary heat exchanger 3 to absorb heat, and exchanges heat with the outside air by the radiator 23 to radiate heat. Thus, the temperature of the secondary coolant is maintained at about 70 ° C. on the inlet side of the radiator 23,
The temperature is maintained at about 60 ° C. on the outlet side of the radiator 23.

In the primary circulation channel 11, a part of the primary coolant cooled by the first heat exchanger 3 is transferred to the communication passage 11.
It supplies to the ion exchanger 14 via B. Here, before the primary coolant is supplied to the ion exchanger 14, it passes through the second heat exchanger 15 and the radiator 16. Second heat exchanger 1
In 5, self-heat exchange is performed between the primary coolant discharged from the ion exchanger 14 and the primary coolant discharged from the first heat exchanger 3. Since the primary coolant discharged from the ion exchanger 14 is cooled by the radiator 16, the temperature of the primary coolant is lower than that of the primary coolant discharged from the first heat exchanger 3. For this reason, in the second heat exchanger 15, the primary coolant discharged from the first heat exchanger 3 is cooled. The primary coolant cooled by the second heat exchanger 15 is further cooled by the radiator 16. The primary coolant discharged from the radiator 16 has a lower temperature than when discharged from the first heat exchanger 3. Therefore, the primary coolant having a low temperature can be supplied to the ion exchanger 14, so that when the ion exchanger 14 removes various ions such as metal ions contained in the primary coolant, the ion exchanger 14 14 can be prevented from significantly reducing the amount of ions that can be adsorbed. Further, the ion exchange resin in the ion exchanger 14 is not significantly deteriorated.

The primary coolant from which various ions such as metal ions have been removed by the ion exchanger 14 is supplied to the second heat exchanger 15 again. In the second heat exchanger 15, heat exchange is performed between the primary coolant discharged from the ion exchanger 14 and the primary coolant discharged from the first heat exchanger 3.
As described above, the primary coolant discharged from the first heat exchanger 3 is cooled by the primary coolant discharged from the ion exchanger 14, but conversely, the primary coolant discharged from the ion exchanger 14 The temperature of the secondary coolant is raised by the primary coolant discharged from the first heat exchanger 3. For this reason, the primary coolant supplied from the ion exchanger 14 is discharged and the communication path 11
When discharged from B, the temperature has risen to substantially the same temperature as when discharged from the first heat exchanger 3. Therefore, it is possible to prevent the temperature of the entire primary cooling system 1 from being significantly reduced.

Here, if the second heat exchanger 15 is not provided,
Consider a case where the primary coolant is cooled only by the radiator 16. Now, a temperature at which the ion exchange resin in the ion exchanger 14 significantly deteriorates, for example, 60 ° C., is defined as a heat-resistant temperature (hereinafter referred to as “heat-resistant temperature”) TG of the ion exchange resin.
At this time, by increasing the cooling capacity of the radiator 16,
It is possible to cool the primary coolant to a temperature below 60 ° C. However, if the cooling capacity of the radiator 16 is excessively increased, the overall temperature of the primary cooling system 1 will be significantly lowered, and the fuel cell FC may not be able to operate in a suitable temperature range. For this reason, as shown in FIG. 3B, when the temperature of the primary coolant is adjusted so that the fuel cell FC can be operated in a suitable temperature range, the primary coolant flowing into the primary coolant ion exchanger 55 Cannot be lowered to the heat-resistant temperature TG. In this case, since the primary cooling liquid having a temperature equal to or higher than the heat-resistant temperature TG is supplied to the ion exchanger 14, deterioration of the ion exchange resin is accelerated. As described above, when the second heat exchanger 15 is not provided, it is possible to separately manage the temperature of the primary coolant supplied to the ion exchanger 14 and the temperature of the primary coolant supplied to the fuel cell FC. Can not. Therefore, the temperature of the primary coolant is reduced by the ion exchanger 14.
, The fuel cell FC becomes overcooled,
Deterioration of the ion exchange resin in the ion exchanger is promoted when the requirement of the fuel cell FC is met.

On the other hand, a change in temperature of the primary coolant in the communication passage 11B of the cooling device M according to the present invention will be described with reference to FIG. As shown in FIG. 3 (a), the second heat exchanger 15 is discharged from the first heat exchanger 3 (FIG. 1) and supplied to the second heat exchanger 15 (point A). By passing through, it is cooled to a temperature lower than the heat resistant temperature TG (point B). Subsequently, the primary coolant supplied to the radiator 16 is cooled to a lower temperature (point C). Thereafter, the primary coolant discharged from the ion exchanger 14 is again supplied to the second heat exchanger 15. In the second heat exchanger 15, between the primary coolant discharged from the first heat exchanger 3 and the primary coolant discharged from the ion exchanger 14, a white arrow in FIG. Heat transfer takes place as shown. Due to this heat transfer, the primary coolant discharged from the first heat exchanger 3 is cooled, and the primary coolant discharged from the ion exchanger 14 is heated. In this manner, the self-heat exchange is performed with the primary coolant, and the primary coolant discharged from the ion exchanger 14 is at a temperature (point A) of the primary coolant discharged from the first heat exchanger 3. Temperature (point D). Thus, the second heat exchanger 1
5 before and after passing through the second heat exchanger 15
Temperature control can be performed separately between the secondary coolants. Specifically, a low-temperature primary coolant can be supplied to the ion exchanger 15, and the primary coolant for cooling the fuel cell FC does not become excessively cooled. Therefore, even if the temperature of the primary coolant supplied to the ion exchanger 14 is adjusted to, for example, 60 ° C., the temperature of the primary coolant supplied to the fuel cell FC can be adjusted to about 70 ° C. The battery FC is placed in a suitable temperature range, for example, 7
It can operate in the range of 5 ° C to 85 ° C. In this way, it is possible to prevent the ion exchange resin from being severely deteriorated in the ion exchanger and to operate the fuel cell in a suitable temperature range.

The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment. For example, a mode in which a heat exchanger is used as the radiator 16 and the cooling liquid is supplied from the secondary cooling system may be adopted.

[0029]

As described above, according to the present invention, by controlling two temperatures in one cooling system, severe deterioration of the ion exchange resin in the ion exchanger can be prevented, and it is suitable for a fuel cell. It is possible to provide a cooling device for a fuel cell that can supply a cooling liquid having a desired temperature.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram of a cooling device for a fuel cell vehicle according to an embodiment of the present invention.

FIG. 2 is a partial sectional view showing a cell structure of the fuel cell shown in FIG.

FIGS. 3A and 3B are graphs showing a change in temperature of a primary coolant supplied to an ion exchanger, wherein FIG. 3A is for a fuel cell cooling device according to the present invention, and FIG. It is for a cooling device.

FIG. 4 is a circuit configuration diagram of a conventional fuel cell cooling device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Primary cooling system 2 Secondary cooling system 3 1st heat exchanger 11 Primary circulation flow path 11A Bypass flow path 11B Communication path 12 Primary circulation pump 13 Temperature controller 14 Ion exchanger 15 Second heat exchanger 16 Heat radiation Unit 21 Secondary circulation flow path 22 Secondary circulation pump 23 Radiator FC Fuel cell M Cooling device for fuel cell

Claims (1)

[Claims] 1. A cooling system for circulating and supplying a coolant to a fuel cell to cool the fuel cell, a circulation pump for circulating the coolant, and a first heat for cooling a coolant discharged from the fuel cell. An exchanger, an ion exchanger using an ion exchange resin for removing ions in the coolant, a radiator for cooling the coolant, and a second heat exchanger for self-exchanging the coolant. ,
The second heat exchanger is arranged in parallel with the inlet side and the outlet side of the coolant in the fuel cell, and the coolant discharged from the first heat exchanger is the second heat exchanger. An exchanger, the radiator, and the ion exchanger flow in this order, and the primary coolant discharged from the ion exchanger is configured to be supplied to the second heat exchanger; In the second heat exchanger, the coolant discharged from the first heat exchanger and the coolant discharged from the ion exchanger flow in opposition to each other, and are discharged from the first heat exchanger. By performing self-heat exchange between the coolant and the coolant discharged from the ion exchanger, the coolant discharged from the first heat exchanger is cooled and the ion exchange is performed. The temperature of the cooling liquid discharged from the vessel rises. Fuel cell, characterized in Rukoto cooling device.