KR101679975B1 - Air supply method of fuel cell system - Google Patents

Air supply method of fuel cell system Download PDF

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Publication number
KR101679975B1
KR101679975B1 KR1020150073899A KR20150073899A KR101679975B1 KR 101679975 B1 KR101679975 B1 KR 101679975B1 KR 1020150073899 A KR1020150073899 A KR 1020150073899A KR 20150073899 A KR20150073899 A KR 20150073899A KR 101679975 B1 KR101679975 B1 KR 101679975B1
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KR
South Korea
Prior art keywords
air
fuel cell
cell stack
cooling
temperature
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KR1020150073899A
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Korean (ko)
Inventor
이현재
이종현
전의식
Original Assignee
현대자동차주식회사
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Priority to KR1020150073899A priority Critical patent/KR101679975B1/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04082—Arrangements for control of reactant parameters, e.g. pressure or concentration
    • H01M8/04089—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04082—Arrangements for control of reactant parameters, e.g. pressure or concentration
    • H01M8/04089—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants
    • H01M8/04119—Arrangements for control of reactant parameters, e.g. pressure or concentration of gaseous reactants with simultaneous supply or evacuation of electrolyte; Humidifying or dehumidifying
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04298—Processes for controlling fuel cells or fuel cell systems
    • H01M8/04313—Processes for controlling fuel cells or fuel cell systems characterised by the detection or assessment of variables; characterised by the detection or assessment of failure or abnormal function
    • H01M8/04492—Humidity; Ambient humidity; Water content
    • H01M8/04522—Humidity; Ambient humidity; Water content of cathode exhausts
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Abstract

The present invention relates to a method of supplying air to a fuel cell system capable of effectively controlling the humidity in a fuel cell stack as well as preventing air overheating by adjusting the temperature of supplied air supplied to the fuel cell stack by a heat exchanger for air cooling .
The air supply method of the fuel cell system according to the present invention cools the compressed supply air to a proper operating temperature of the fuel cell stack by an air-cooling heat exchanger while supplying compressed air to the fuel cell stack, Controlling the supply air to raise the temperature of the fuel cell stack to avoid a dry state if the cell stack is in a dry state and to prevent the wet state of the fuel cell stack by cooling the supply air when the fuel cell stack is wet .

Description

TECHNICAL FIELD [0001] The present invention relates to an air supply method for a fuel cell system,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell system, and more particularly, to a fuel cell system capable of effectively controlling the humidity in a fuel cell stack as well as preventing overheating of air by adjusting the temperature of supplied air supplied to the fuel cell stack by an air- To an air supply method of a fuel cell system.

Fuel cell systems are a kind of power generation system that converts the chemical energy of fuel directly into electric energy.

The fuel cell system includes a fuel cell stack having a fuel electrode and an air electrode for generating electrical energy, a fuel supply system for supplying fuel to the fuel electrode of the fuel cell stack, an air supply system for supplying air to the air electrode of the fuel cell stack, And a heat and water management system for removing the reaction heat of the battery stack to the outside of the system and controlling the operating temperature of the fuel cell stack.

On the other hand, the supply air must be compressed and supplied during the variable pressure operation of the fuel cell system. Since the temperature of the supply air is being compressed by the compressor, proper cooling of the supply air is required in the high output operation region.

Accordingly, in a pressurized operation fuel cell system, an air cooling heat exchanger is applied to prevent overheating of air in a high output region.

The refrigerant circulating flow path is connected to the air cooling heat exchanger, and the refrigerant circulates in the air cooling heat exchanger through the refrigerant circulating flow path to cool the compressed supply air to a temperature suitable for operation of the fuel cell stack. At this time, when the temperature of the air-cooling refrigerant for heat exchange with the supply air becomes higher than the set temperature, the rotation speed (rpm) of the refrigerant circulation pump is increased to prevent the temperature of the supply air from being overheated.

As described above, the conventional fuel cell system only performs cooling of the supply air by the air-cooling heat exchanger and does not apply appropriate control for humidity control in the fuel cell stack, there was.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fuel cell system capable of significantly improving the operation stability of a fuel cell stack by performing humidity control in a fuel cell stack through temperature control of supply air, The purpose is to provide a supply method.

According to an aspect of the present invention, there is provided a method of supplying air to a fuel cell system,

Cooling the pressurized feed air to a drive operating temperature of the fuel cell stack by an air-cooling heat exchanger while supplying compressed air to the fuel cell stack,

And controlling the temperature of the supply air so that the fuel cell stack avoids a dry state when the fuel cell stack is in a dry state,

And controls the supply air to be cooled to avoid the wet state of the fuel cell stack when the fuel cell stack is in a wet state.

The circulating flow rate of the air cooling refrigerant supplied to the air cooling heat exchanger is reduced to raise the temperature of the supply air when the fuel cell stack is in a normal operating condition.

The number of revolutions of the air-cooling circulating pump for circulating the air-cooling refrigerant to the air-cooling heat exchanger is reduced more than when the fuel cell stack is in the normal operating state, The circulating flow rate is reduced and the supply air is heated by reducing the circulating flow rate of the refrigerant for air cooling.

Further comprising the step of measuring a first measurement temperature which is a temperature of the air-cooling refrigerant or the supply air,

Wherein when the first measured temperature is higher than the first reference value after the temperature of the supplied air is raised, the number of revolutions of the circulating pump for air cooling is maintained in accordance with normal operating conditions of the fuel cell stack,

And the first reference value is a reference temperature that satisfies a humidity condition that can avoid a dry state of the fuel cell stack.

And the circulation flow rate of the air cooling refrigerant supplied to the air cooling heat exchanger is increased to cool the supply air when the fuel cell stack is in a wet state.

The number of revolutions of the air-cooling circulation pump for circulating the air-cooling refrigerant to the air-cooling heat exchanger is increased more than the number of revolutions of the air-cooling circulation pump when the fuel cell stack is in the normal operation state, The circulation flow rate is increased and the supply air is cooled through the circulation flow rate increase of the air cooling refrigerant.

Further comprising the step of measuring a first measurement temperature which is a temperature of the air-cooling refrigerant or the supply air,

If the first measured temperature is lower than the second reference value after the cooling of the supply air, maintains the number of revolutions of the coolant circulation pump for air cooling according to normal operating conditions of the fuel cell stack,

And the second reference value is a reference temperature that satisfies a humidity condition that can avoid the wet state of the fuel cell stack.

According to another aspect of the present invention, there is provided a method of supplying air to a fuel cell system,

Cooling the pressurized feed air to a drive operating temperature of the fuel cell stack by an air-cooling heat exchanger while supplying compressed air to the fuel cell stack,

Wherein the controller controls the fuel cell stack to avoid a dry state by raising the temperature of the fuel cell stack and the temperature of the supply air when the fuel cell stack is in a dry state,

And controls the cooling of the supply air and the temperature rise of the fuel cell stack to avoid the wet state of the fuel cell stack when the fuel cell stack is in a wet state.

Wherein the circulating flow rate of the air cooling refrigerant supplied to the air cooling heat exchanger is reduced to raise the supply air temperature when the fuel cell stack is in a normal operating condition of the fuel cell stack, And the temperature of the fuel cell stack is lower than that at the normal operating condition of the fuel cell stack.

The number of revolutions of the air-cooling circulation pump for circulating the air-cooling refrigerant to the air-cooling heat exchanger is reduced compared with the case of the normal operation condition of the fuel cell stack when the fuel cell stack is in a dry state, Reducing the circulating flow rate, raising the temperature of the supply air by reducing the circulating flow rate of the refrigerant for air cooling,

The circulation flow rate of the coolant for stack cooling is increased by increasing the number of revolutions of the coolant circulation pump for stack cooling that circulates the coolant for stack cooling to the fuel cell stack when the fuel cell stack is in a normal operation condition of the fuel cell stack, And the temperature of the fuel cell stack is reduced by increasing the circulation flow rate of the refrigerant.

Further comprising the step of measuring a first measurement temperature which is a temperature of the air-cooling refrigerant or the supply air,

Wherein when the first measured temperature is higher than the first reference value after the temperature of the supplied air is raised, the number of revolutions of the circulating pump for air cooling is maintained in accordance with normal operating conditions of the fuel cell stack,

And the first reference value is a reference temperature that satisfies a humidity condition that can avoid a dry state of the fuel cell stack.

Wherein the circulating flow rate of the air cooling refrigerant supplied to the air cooling heat exchanger is increased to cool the supply air more than when the fuel cell stack is in the normal operating condition, And the temperature of the fuel cell stack is increased as compared with the normal operating condition of the fuel cell stack.

The number of revolutions of the air-cooling circulation pump for circulating the air-cooling refrigerant to the air-cooling heat exchanger is increased more than the number of revolutions of the air-cooling circulation pump when the fuel cell stack is in a normal operating condition, Increasing the circulating flow rate, cooling the supply air by increasing the circulating flow rate of the air-cooling refrigerant,

The circulation flow rate of the coolant for stack cooling is reduced by reducing the number of revolutions of the coolant circulation pump for stack cooling that circulates the coolant for stack cooling to the fuel cell stack when the fuel cell stack is in a normal operating condition of the fuel cell stack, And the temperature of the fuel cell stack is increased by reducing the circulating flow rate of the refrigerant.

Further comprising the step of measuring a first measurement temperature which is a temperature of the air-cooling refrigerant or the supply air,

If the first measured temperature is lower than the second reference value after the cooling of the supply air, maintains the number of revolutions of the coolant circulation pump for air cooling according to normal operating conditions of the fuel cell stack,

And the second reference value is a reference temperature that satisfies a humidity condition that can avoid the wet state of the fuel cell stack.

Another aspect of the present invention is a fuel cell system including a fuel cell stack, an air supply system for supplying supply air to the fuel cell stack, a fuel supply system for supplying fuel to the fuel cell stack, a compressor for compressing supply air, A coolant circulating flow path for circulating the coolant for cooling the air to the air cooling heat exchanger, and a coolant for stack cooling for circulating the coolant for stack cooling to the fuel cell stack 1. A method of supplying air to a fuel cell system having a circulating flow path,

Cooling the pressurized supply air to a drive operating temperature of the fuel cell stack by an air-cooling heat exchanger while supplying compressed air to the fuel cell stack,

The first measurement temperature which is the temperature of the coolant for air cooling or the supply air and the second measurement temperature which is the temperature of the coolant for stack cooling are measured and then the measured temperature difference value obtained by subtracting the first measured temperature from the second measured temperature is calculated In addition,

And controlling the fuel cell stack to avoid the dry state by increasing the temperature of the supply air and the temperature of the fuel cell stack if the measured temperature difference value is greater than the third reference value,

If the measured temperature difference value is smaller than a fourth reference value, control to avoid the wet state of the fuel cell stack due to cooling of the supply air and a temperature rise of the fuel cell stack,

The third reference value is a reference value that satisfies a humidity condition in which the inside of the fuel cell stack can avoid a dry state,

And the fourth reference value is a reference value that satisfies a humidity condition in which the interior of the fuel cell stack can avoid the wet state.

If the measured temperature difference value is greater than a third reference value, the circulating flow rate of the air-cooling refrigerant supplied to the air-cooling heat exchanger is reduced to raise the supply air temperature in the normal operating condition of the fuel cell stack, And the temperature of the fuel cell stack is lower than that at the normal operating condition of the fuel cell stack by increasing the circulating flow rate of the coolant for stack cooling circulated in the stack.

Wherein the number of revolutions of the air-cooling circulation pump for circulating the air-cooling refrigerant to the air-cooling heat exchanger is reduced when the measurement temperature difference is larger than the third reference value, The circulation flow rate of the refrigerant for cooling the air is decreased, the temperature of the supply air is raised through the circulation flow rate reduction of the air-

The circulation flow rate of the coolant for stack cooling is increased by increasing the number of revolutions of the coolant circulation pump for stack cooling that circulates the coolant for stack cooling to the fuel cell stack when the fuel cell stack is in a normal operation condition of the fuel cell stack, And the temperature of the fuel cell stack is reduced by increasing the circulation flow rate of the refrigerant.

Wherein when the first measured temperature is higher than the first reference value after the temperature of the supplied air is raised, the number of revolutions of the circulating pump for air cooling is maintained in accordance with normal operating conditions of the fuel cell stack,

And the first reference value is a reference temperature that satisfies a humidity condition that can avoid a dry state of the fuel cell stack.

Wherein the circulation flow rate of the air cooling refrigerant supplied to the air cooling heat exchanger is increased to cool the supply air more than the normal operating condition of the fuel cell stack when the measured temperature difference value is smaller than the fourth reference value, The circulating flow rate of the coolant for cooling the stack circulated in the cell stack is reduced to increase the temperature of the fuel cell stack at the normal operating condition of the fuel cell stack.

Wherein when the measured temperature difference value is smaller than the fourth reference value, the number of revolutions of the air-cooling circulation pump for circulating the air-cooling refrigerant to the air-cooling heat exchanger is increased than when the fuel- The circulation flow rate of the cooling refrigerant is increased, the supply air is cooled through the circulation flow rate increase of the air cooling refrigerant,

The circulation flow rate of the coolant for stack cooling is reduced by reducing the number of revolutions of the coolant circulation pump for stack cooling that circulates the coolant for stack cooling to the fuel cell stack when the fuel cell stack is in a normal operating condition of the fuel cell stack, And the temperature of the fuel cell stack is increased by reducing the circulating flow rate of the refrigerant.

If the first measured temperature is lower than the second reference value after the cooling of the supply air, maintains the number of revolutions of the coolant circulation pump for air cooling according to normal operating conditions of the fuel cell stack,

And the second reference value is a reference temperature that satisfies a humidity condition that can avoid the wet state of the fuel cell stack.

According to the present invention, it is possible to appropriately induce the increase / decrease of the saturated water vapor pressure by raising / lowering the temperature of the supply air in the dry state or the wet state in the fuel cell stack, Therefore, the humidity control in the fuel cell stack can be very effectively performed, thereby greatly improving the operation stability of the fuel cell stack.

In addition, the present invention is advantageous in that the humidity in the fuel cell stack can be more effectively controlled by adjusting the temperature of the fuel cell stack, in addition to the temperature control of the supply air, depending on the dry state or the wet state in the fuel cell stack.

 The present invention also provides a method of controlling the temperature of a supply air and a temperature of a fuel cell stack in such a manner as to maintain a constant temperature difference between a coolant for stack cooling and a coolant (or supply air) Can be performed more accurately.

1 is a view showing an example of a pressurized operation fuel cell system.
FIG. 2 is a flowchart showing an air supply method of the fuel cell system according to the first embodiment of the present invention.
3 is a flowchart showing an air supply method of the fuel cell system according to the second embodiment of the present invention.
4 is a flowchart showing an air supply method of the fuel cell system according to the third embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. For the sake of convenience, the size, line thickness, and the like of the components shown in the drawings referenced in the description of the present invention may be exaggerated somewhat. The terms used in the description of the present invention are defined in consideration of the functions of the present invention, and thus may be changed depending on the user, the intention of the operator, customs, and the like. Therefore, the definition of this term should be based on the contents of this specification as a whole.

1 is a view showing an example of a pressurized operation type fuel cell system. As shown in the figure, the pressurized operation type fuel cell system includes a fuel cell stack 10 having an air electrode 10a and a fuel electrode 10b, An air supply line 11 for supplying supply air to the air electrode 10a of the fuel cell stack 10, a fuel supply line 12 for supplying fuel to the fuel electrode 10b of the fuel cell stack 10, A compressor 13 installed in the middle of the compressor 13 for compressing the supply air, an air cooling heat exchanger 14 disposed downstream of the compressor 13 to cool the compressed air to prevent overheating of the supplied air, A humidifier 15 for humidifying air, and the like.

The refrigerant circulating flow path 17 for air cooling is connected to the air-cooling heat exchanger 14, and the air-cooling refrigerant is introduced into the air-cooling heat exchanger 14 through the air- The refrigerant for air cooling is configured to cool the compressed supply air passing through the air supply line 11 by circulation. A coolant circulation pump 16 for air cooling for circulating the coolant is provided at one side of the coolant circulation flow path 17.

The fuel cell stack 10 is connected to the coolant circulation passage 18 for cooling the stack and the coolant for cooling the stack flows into the fuel cell stack 10 through the coolant circulation channel 18 for stack cooling The coolant for cooling the fuel cell stack 10 is configured. A coolant circulation pump 19 for cooling the stack for circulating the coolant is provided at one side of the coolant circulation flow path 18 for stack cooling.

A typical air supply method by the pressurized operation type fuel cell system will be described below.

First, compressed air supplied from the outside is compressed by the compressor (13), and then the compressed air is supplied to the air electrode (10a) of the fuel cell stack (10).

At this time, before the supply air is supplied to the air electrode 10a of the fuel cell stack 10, the supply air is supplied to the fuel cell stack 10 by the air-cooling heat exchanger 14, (A proper temperature at which the operation of the fuel cell stack 10 can be normally safely performed), and then supplies the cooled air to the air electrode 10a of the fuel cell stack 10. [ That is, the supply air is supplied to the air electrode 10a of the fuel cell stack 10 in a state where overheat is prevented by the air-cooling heat exchanger 14. [

FIG. 2 is a flowchart showing an air supply method of the fuel cell system according to the first embodiment of the present invention.

The first measured temperature T1 is measured during the supply of compressed air to the air electrode 10a of the fuel cell stack 10 (S1). Here, the first measurement temperature T1 is the temperature of the air-cooling refrigerant or the supply air.

Thereafter, it is determined whether the inside of the fuel cell stack 10 is dry-out (S2).

When the inside of the fuel cell stack 10 is in a dry state, the normal operation condition of the fuel cell stack 10 (here, the normal operation condition means that the inside of the fuel cell stack 10 is in a normal (I.e., a state in which the operation is performed), the supply air is heated (S3). At this time, the supply air is heated by reducing the rotation speed (RPM) of the refrigerant circulation pump 16 for air cooling rather than the normal operating condition of the fuel cell stack 10.

The inside of the fuel cell stack 10 can appropriately avoid the drying state by raising the temperature of the supply air. More specifically, the circulation flow rate of the air-cooling refrigerant is reduced as compared with the normal operating condition of the fuel cell stack 10 due to the decrease in the RPM of the refrigerant circulation pump 16 for air-cooling, As the coolant for cooling the air exchanges heat with the supply air, the supply air is relatively heated, so that the supply air is introduced into the fuel cell stack 10 in an increased amount of water, Can be adjusted to a suitable humidity condition avoiding the dry state.

After the temperature of the supply air is raised in this manner, it is determined whether the temperature T1 of the air-cooling refrigerant or the supply air is higher than the first reference value C1 (S4). Here, the first reference value C1 is a reference temperature that satisfies a humidity condition in which the inside of the fuel cell stack 10 can avoid a dry state.

If it is determined that the first measured temperature T1 is larger than the first reference value C1, the rotational speed RPM of the refrigerant circulating pump 16 for air cooling is adjusted to the normal operating condition, (S5).

If it is determined that the first measured temperature T1 is smaller than the first reference value C1, the above-described step S3 is repeated.

On the other hand, if it is determined that the interior of the fuel cell stack 10 is not dry, the inside of the fuel cell stack 10 is judged to be flooded (S6).

When the inside of the fuel cell stack 10 is wet, the supply air is cooled more than when the fuel cell stack 10 is in the normal operating condition (S7). At this time, the supply air is cooled by increasing the number of revolutions (RPM) of the refrigerant circulation pump 16 for air cooling more than when the fuel cell stack 10 is in the normal operating condition.

By cooling the supply air, the inside of the fuel cell stack 10 can appropriately avoid the wet state. More specifically, the circulation flow rate of the refrigerant for air cooling is increased compared to the normal operating condition of the fuel cell stack 10 by increasing the RPM of the refrigerant circulation pump 16 for air cooling, As the coolant for cooling the air exchanges heat with the supply air, the supply air is relatively cooled, so that the supply air is introduced into the fuel cell stack 10 in a state in which the water amount is reduced, whereby the inside of the fuel cell stack 10 Can be adjusted to appropriate humidity conditions avoiding wetting conditions.

After cooling the supply air, it is determined whether the first measured temperature T1 is smaller than the second reference value C2 (S8). Here, the second reference value C2 is a reference temperature that satisfies a humidity condition in which the inside of the fuel cell stack 10 can avoid the wet state.

If it is determined that the first measured temperature T1 is smaller than the second reference value C2, the rotational speed RPM of the refrigerant circulating pump 16 for air cooling is adjusted to the normal operating condition, (S5).

If it is determined that the first measured temperature T1 is larger than the second reference value C2, the above-described step S7 is repeated.

In the above-described steps S2 and S4, the dry state or the wet state of the fuel cell stack 10 may be detected through a humidity sensor or the like, or may be detected through various detection logic and the like.

3 is a flowchart showing an air supply method of the fuel cell system according to the second embodiment of the present invention.

The first measured temperature T1 is measured during the supply of compressed air to the air electrode 10a of the fuel cell stack 10 (S11). Here, the first measurement temperature T1 is the temperature of the air-cooling refrigerant or the supply air.

Thereafter, it is determined whether the inside of the fuel cell stack 10 is dry (S12).

If the inside of the fuel cell stack 10 is dry, the temperature of the fuel cell stack 10 is decreased (S13) while the temperature of the supply air is raised more than the normal operating condition of the fuel cell stack 10. At this time, the number of revolutions (RPM) of the refrigerant circulation pump 16 for air cooling is decreased to reduce the circulating flow rate of the air-cooling refrigerant, thereby raising the supply air temperature, , The temperature of the fuel cell stack 10 is decreased by increasing the number of revolutions (RPM) of the coolant circulation pump 19 for stack cooling more than when the normal operation condition of the fuel cell stack 10 is established.

The temperature of the supply air and the temperature of the fuel cell stack 10 can be appropriately avoided in the interior of the fuel cell stack 10 due to the drying air. More specifically, when the number of revolutions (RPM) of the refrigerant circulating pump 16 for air cooling is reduced compared to the normal operating condition of the fuel cell stack 10, the circulating flow rate of the refrigerant for air cooling decreases, As the coolant for cooling the air exchanges heat with the supply air, the supply air is relatively heated, and the supply air is introduced into the fuel cell stack 10 in an increased amount of water. In addition, when the number of revolutions (RPM) of the refrigerant circulation pump 19 for stack cooling is increased compared to the normal operating condition of the fuel cell stack 10, the circulation flow rate of the coolant for stack cooling circulating in the fuel cell stack 10 The temperature of the fuel cell stack 10 can be reduced as the refrigerant for stack cooling is heat-exchanged with the fuel cell stack 10.

By raising the temperature of the supply air and reducing the temperature of the fuel cell stack 10, the interior of the fuel cell stack 10 can be adjusted to an appropriate humidity condition avoiding the dry state.

After the temperature of the supply air is raised and the temperature of the fuel cell stack 10 is reduced, it is determined whether the first measured temperature T1 is greater than the first reference value C1 (S14). Here, the first reference value C1 is a reference temperature that satisfies a humidity condition in which the inside of the fuel cell stack 10 can avoid a dry state.

When it is determined that the first measured temperature T1 is larger than the first reference value C1, the rotational speed RPM of the refrigerant circulating pump 16 for air cooling and the rotational speed RPM of the refrigerant circulating pump 19 ) To the normal operating conditions to normally operate the refrigerant circulation pump 16 for air cooling (S15).

If it is determined that the first measured temperature T1 is smaller than the first reference value C1, the above-described step S13 is repeated.

On the other hand, if it is determined that the interior of the fuel cell stack 10 is not in the dry state, it is determined whether the inside of the fuel cell stack 10 is wet (S16).

When the inside of the fuel cell stack 10 is in the wet state, the temperature of the fuel cell stack 10 is increased in addition to cooling the supply air at the normal operating condition of the fuel cell stack 10 (S17). At this time, the number of revolutions (RPM) of the refrigerant circulation pump 16 for air cooling is increased to increase the circulating flow rate of the air-cooling refrigerant, thereby cooling the supply air more than the normal operating condition of the fuel cell stack 10 The RPM of the circulation pump 19 for stack cooling is reduced to reduce the circulation flow rate of the coolant for stack cooling so that the temperature of the fuel cell stack 10 is lowered .

By cooling the supply air and increasing the temperature of the fuel cell stack 10, the inside of the fuel cell stack 10 can appropriately avoid the wet state. More specifically, the circulation flow rate of the air-cooling refrigerant is increased by the increase of the RPM of the refrigerant circulation pump 16 for air cooling compared with the normal operating condition of the fuel cell stack 10, As the coolant for air cooling exchanges heat with the supply air, the supply air is relatively cooled, and the supply air is introduced into the fuel cell stack 10 with its water amount reduced. In addition, when the number of revolutions (RPM) of the coolant circulation pump 19 for stack cooling is reduced compared to the normal operating condition of the fuel cell stack 10, the circulating flow rate of the coolant for stack cooling, And the temperature of the fuel cell stack 10 can be relatively increased as the coolant for cooling the stack is cooled with the fuel cell stack 10.

By cooling the supply air and increasing the temperature of the fuel cell stack 10, the interior of the fuel cell stack 10 can be adjusted to an appropriate humidity condition avoiding the dry state.

After cooling the supply air, it is determined whether the first measured temperature T1 is smaller than the second reference value C2 (S18). Here, the second reference value C2 is a reference temperature that satisfies a humidity condition in which the inside of the fuel cell stack 10 can avoid the wet state.

When it is determined that the first measured temperature T1 is smaller than the second reference value C2, the rotational speed RPM of the refrigerant circulating pump 16 for air cooling and the rotational speed RPM of the refrigerant circulating pump 19 ) To the normal operating condition of the fuel cell stack 10 to operate the air-cooling refrigerant circulation pump 16 normally (S15).

If it is determined that the first measured temperature T1 is larger than the second reference value C2, the above-described step S17 is repeated.

In the above-described steps S12 and S14, the dry state or the wet state of the fuel cell stack 10 may be detected through a humidity sensor or the like, or may be detected through various detection logic and the like.

The air supply method of the fuel cell system according to the second embodiment has an advantage that the humidity control in the fuel cell stack can be performed more effectively by controlling the temperature of the fuel cell stack in addition to the temperature control of the supply air.

4 shows a method of supplying air to the fuel cell system according to the third embodiment of the present invention.

The first measurement temperature T1 and the second measurement temperature T2 are measured during the supply of the compressed air to the air electrode 10a of the fuel cell stack 10 (S21). Here, the first measurement temperature T1 is the temperature of the air-cooling refrigerant or the supply air, and the second measurement temperature T2 is the temperature of the refrigerant for stack cooling.

Thereafter, a measured temperature difference value (DELTA T = T2-T1) obtained by subtracting the first measured temperature (T1) from the second measured temperature (T2) is calculated (S22). The measured temperature difference value may be determined in advance through various empirical equations or the like to obtain data on an appropriate temperature difference value that can maintain the temperature in accordance with the normal operating condition of the fuel cell stack 10. [

It is determined whether the calculated measured temperature difference value? T is larger than the third reference value C3 (S23). Here, the third reference value C3 is a positive constant value as a reference value that satisfies the humidity condition in which the inside of the fuel cell stack 10 can avoid the dry state.

If the measured temperature difference value? T is larger than the third reference value C3 in step S22, the internal temperature of the fuel cell stack 10 is relatively high and the temperature of the supplied air is relatively low The inside of the fuel cell stack 10 corresponds to a dry state. In other words, it can be understood that the step S23 is a step of determining whether the interior of the fuel cell stack 10 is in a dry state.

If the measured temperature difference value DELTA T is larger than the third reference value C3, the temperature of the fuel cell stack 10 is decreased while raising the supply air temperature in the normal operating condition of the fuel cell stack 10 S24). At this time, the number of revolutions (RPM) of the refrigerant circulation pump 16 for air cooling is decreased to reduce the circulating flow rate of the air-cooling refrigerant, thereby raising the supply air temperature, , The temperature of the fuel cell stack 10 is decreased by increasing the number of revolutions (RPM) of the coolant circulation pump 19 for stack cooling more than when the normal operation condition of the fuel cell stack 10 is established.

The temperature of the supply air and the temperature of the fuel cell stack 10 can be appropriately avoided in the interior of the fuel cell stack 10 due to the drying air. More specifically, when the number of revolutions (RPM) of the refrigerant circulating pump 16 for air cooling is reduced compared to the normal operating condition of the fuel cell stack 10, the circulating flow rate of the refrigerant for air cooling decreases, As the coolant for cooling the air exchanges heat with the supply air, the supply air is relatively heated, and the supply air is introduced into the fuel cell stack 10 in an increased amount of water. In addition, when the number of revolutions (RPM) of the refrigerant circulation pump 19 for stack cooling is increased compared to the normal operating condition of the fuel cell stack 10, the circulation flow rate of the coolant for stack cooling circulating in the fuel cell stack 10 The temperature of the fuel cell stack 10 can be reduced as the refrigerant for stack cooling is heat-exchanged with the fuel cell stack 10.

By raising the temperature of the supply air and reducing the temperature of the fuel cell stack 10, the interior of the fuel cell stack 10 can be adjusted to an appropriate humidity condition avoiding the dry state.

Thereafter, it is determined whether the first measured temperature T1 is larger than the first reference value C1 (S25). Here, the first reference value C1 is a reference temperature that satisfies a humidity condition in which the inside of the fuel cell stack 10 can avoid a dry state.

When it is determined that the first measured temperature T1 is larger than the first reference value C1, the rotational speed RPM of the refrigerant circulating pump 16 for air cooling and the rotational speed RPM of the refrigerant circulating pump 19 ) To the normal operating condition of the fuel cell stack 10 to normally operate the refrigerant circulation pump 16 for air cooling (S26).

If it is determined that the temperature T1 of the air-cooling refrigerant or the supply air is smaller than the first reference value C1, the above-described step S24 is repeated.

On the other hand, if the measured temperature difference value? T is not larger than the third reference value C3, it is determined whether the measured temperature difference value? T is smaller than the fourth reference value C4 (S27). Here, the fourth reference value C4 is a negative constant value as a reference value that satisfies the humidity condition in which the inside of the fuel cell stack 10 can avoid the wet state.

If the measured temperature difference value? T is smaller than the fourth reference value C4 in step S27, the internal temperature of the fuel cell stack 10 is relatively low and the temperature of the supplied air is relatively high It is understood that the inside of the fuel cell stack 10 corresponds to the wet state. In other words, it can be seen that the step S27 described above is a step of determining whether or not the interior of the fuel cell stack 10 is in the wet state.

If the measured temperature difference value DELTA T is larger than the fourth reference value C4, the supply air is cooled and the temperature of the fuel cell stack 10 is increased as compared with the normal operating condition of the fuel cell stack 10 S28). At this time, the number of revolutions (RPM) of the coolant circulation pump 16 for air cooling is increased to reduce the circulating flow rate of the coolant for cooling the air, thereby raising the supply air temperature, The RPM of the circulation pump 19 for stack cooling is reduced to reduce the circulation flow rate of the coolant for stack cooling so that the temperature of the fuel cell stack 10 is lowered .

By cooling the supply air and increasing the temperature of the fuel cell stack 10, the inside of the fuel cell stack 10 can appropriately avoid the wet state. More specifically, the circulation flow rate of the air-cooling refrigerant is increased by the increase of the RPM of the refrigerant circulation pump 16 for air cooling compared with the normal operating condition of the fuel cell stack 10, As the coolant for air cooling exchanges heat with the supply air, the supply air is relatively cooled, and the supply air is introduced into the fuel cell stack 10 with its water amount reduced. In addition, when the number of revolutions (RPM) of the coolant circulation pump 19 for stack cooling is reduced compared to the normal operating condition of the fuel cell stack 10, the circulating flow rate of the coolant for stack cooling, And the temperature of the fuel cell stack 10 can be relatively increased as the coolant for cooling the stack is cooled with the fuel cell stack 10.

By cooling the supply air and increasing the temperature of the fuel cell stack 10, the interior of the fuel cell stack 10 can be adjusted to an appropriate humidity condition avoiding the dry state.

Thereafter, it is determined whether the first measured temperature T1 is smaller than the second reference value C2 (S29). Here, the second reference value C2 is a reference temperature that satisfies a humidity condition in which the inside of the fuel cell stack 10 can avoid the wet state.

When it is determined that the first measured temperature T1 is smaller than the second reference value C2, the rotational speed RPM of the refrigerant circulating pump 16 for air cooling and the rotational speed RPM of the refrigerant circulating pump 19 ) To the normal operating condition to thereby normally operate the refrigerant circulation pump 16 for air cooling (S26).

If it is determined that the first measured temperature T1 is larger than the second reference value C2, the above-described step S28 is repeated.

According to the above-described third embodiment, by controlling the temperature of the supply air and the temperature of the fuel cell stack in such a manner as to maintain a constant temperature difference between the refrigerant for stack cooling and the air-cooling refrigerant (or the supply air) The humidity control of the stack can be performed more accurately.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. .

10: Fuel cell stack 10a: Air electrode
10b: fuel electrode 11: air supply line
12: fuel supply line 13: compressor
14: Heat exchanger for air cooling 15: Humidifier
16: refrigerant circulation pump for air cooling 17: refrigerant circulation flow path for air cooling
18: Refrigerant circulation channel for stack cooling 19: Refrigerant circulation pump for stack cooling

Claims (21)

Cooling the pressurized feed air to a drive operating temperature of the fuel cell stack by an air-cooling heat exchanger while supplying compressed air to the fuel cell stack,
Wherein when the fuel cell stack is in a dry state, the circulating flow rate of the air cooling refrigerant supplied to the air cooling heat exchanger is lower than that in the normal operating condition of the fuel cell stack,
Wherein when the fuel cell stack is in a wet state, the circulation flow rate of the air-cooling refrigerant supplied to the air-cooling heat exchanger is increased to cool the supply air when the fuel cell stack is in a wet state.
delete The method according to claim 1,
The number of revolutions of the air-cooling circulating pump for circulating the air-cooling refrigerant to the air-cooling heat exchanger is reduced more than when the fuel cell stack is in the normal operating state, Wherein the circulating flow rate is reduced and the supply air is heated by reducing the circulating flow rate of the air cooling refrigerant. The method of claim 3,
Further comprising the step of measuring a first measurement temperature which is a temperature of the air-cooling refrigerant or the supply air,
Wherein when the first measured temperature is higher than the first reference value after the temperature of the supplied air is raised, the number of revolutions of the circulating pump for cooling the air is adjusted to the normal operating condition of the fuel cell stack,
Wherein the first reference value is a reference temperature that satisfies a humidity condition capable of avoiding a dry state of the fuel cell stack. delete The method according to claim 1,
The number of revolutions of the air-cooling circulation pump for circulating the air-cooling refrigerant to the air-cooling heat exchanger is increased more than the number of revolutions of the air-cooling circulation pump when the fuel cell stack is in the normal operation state, Wherein the circulating flow rate is increased and the supply air is cooled by increasing the circulating flow rate of the refrigerant for air cooling. The method of claim 6,
Further comprising the step of measuring a first measurement temperature which is a temperature of the air-cooling refrigerant or the supply air,
If the first measured temperature is lower than the second reference value after the cooling of the supplied air, the rotation speed of the coolant circulation pump for air cooling is adjusted to the normal operating condition of the fuel cell stack,
Wherein the second reference value is a reference temperature that satisfies a humidity condition capable of avoiding the wet state of the fuel cell stack. Cooling the pressurized feed air to a drive operating temperature of the fuel cell stack by an air-cooling heat exchanger while supplying compressed air to the fuel cell stack,
Wherein when the fuel cell stack is in a dry state, the fuel cell stack is controlled to avoid the dry state by the temperature increase of the supply air and the temperature decrease of the fuel cell stack,
Wherein when the fuel cell stack is in a wet state, it controls cooling of supply air and temperature rise of the fuel cell stack so as to avoid the wet state of the fuel cell stack. The method of claim 8,
Wherein the circulating flow rate of the air cooling refrigerant supplied to the air cooling heat exchanger is reduced to raise the supply air temperature when the fuel cell stack is in a normal operating condition of the fuel cell stack, Wherein the temperature of the fuel cell stack is lower than that at the normal operating condition of the fuel cell stack by increasing the circulating flow rate of the coolant for stack cooling. The method of claim 9,
The number of revolutions of the air-cooling circulation pump for circulating the air-cooling refrigerant to the air-cooling heat exchanger is reduced compared with the case of the normal operation condition of the fuel cell stack when the fuel cell stack is in a dry state, Reducing the circulating flow rate, raising the temperature of the supply air by reducing the circulating flow rate of the refrigerant for air cooling,
The circulation flow rate of the coolant for stack cooling is increased by increasing the number of revolutions of the coolant circulation pump for stack cooling that circulates the coolant for stack cooling to the fuel cell stack when the fuel cell stack is in a normal operation condition of the fuel cell stack, Wherein the temperature of the fuel cell stack is reduced by increasing the circulation flow rate of the refrigerant. The method of claim 10,
Further comprising the step of measuring a first measurement temperature which is a temperature of the air-cooling refrigerant or the supply air,
Wherein when the first measured temperature is higher than the first reference value after the temperature of the supplied air is raised, the number of revolutions of the circulating pump for cooling the air is adjusted to the normal operating condition of the fuel cell stack,
Wherein the first reference value is a reference temperature that satisfies a humidity condition capable of avoiding a dry state of the fuel cell stack. The method of claim 8,
Wherein the circulating flow rate of the air cooling refrigerant supplied to the air cooling heat exchanger is increased to cool the supply air more than when the fuel cell stack is in the normal operating condition, Wherein the circulating flow rate of the coolant for stack cooling is decreased to increase the temperature of the fuel cell stack when the fuel cell stack is under normal operating conditions. The method of claim 12,
The number of revolutions of the air-cooling circulation pump for circulating the air-cooling refrigerant to the air-cooling heat exchanger is increased more than the number of revolutions of the air-cooling circulation pump when the fuel cell stack is in a normal operating condition, Increasing the circulating flow rate, cooling the supply air by increasing the circulating flow rate of the air-cooling refrigerant,
The circulation flow rate of the coolant for stack cooling is reduced by reducing the number of revolutions of the coolant circulation pump for stack cooling that circulates the coolant for stack cooling to the fuel cell stack when the fuel cell stack is in a normal operating condition of the fuel cell stack, Wherein the temperature of the fuel cell stack is increased by reducing the circulating flow rate of the refrigerant. 14. The method of claim 13,
Further comprising the step of measuring a first measurement temperature which is a temperature of the air-cooling refrigerant or the supply air,
If the first measured temperature is lower than the second reference value after the cooling of the supplied air, the rotation speed of the coolant circulation pump for air cooling is adjusted to the normal operating condition of the fuel cell stack,
Wherein the second reference value is a reference temperature that satisfies a humidity condition capable of avoiding the wet state of the fuel cell stack. An air supply system for supplying air to the fuel cell stack; a fuel supply system for supplying fuel to the fuel cell stack; a compressor for compressing the supply air; A coolant circulation channel for air cooling for circulating the coolant for air cooling to the air cooling heat exchanger, and a stack coolant circulation channel for circulating the coolant for stack cooling to the fuel cell stack. As the air supply method of the air-
Cooling the pressurized supply air to a drive operating temperature of the fuel cell stack by an air-cooling heat exchanger while supplying compressed air to the fuel cell stack,
The first measurement temperature which is the temperature of the coolant for air cooling or the supply air and the second measurement temperature which is the temperature of the coolant for stack cooling are measured and then the measured temperature difference value obtained by subtracting the first measured temperature from the second measured temperature is calculated In addition,
And controlling the fuel cell stack to avoid the dry state by increasing the temperature of the supply air and the temperature of the fuel cell stack if the measured temperature difference value is greater than the third reference value,
If the measured temperature difference value is smaller than a fourth reference value, control to avoid the wet state of the fuel cell stack due to cooling of the supply air and a temperature rise of the fuel cell stack,
The third reference value is a reference value that satisfies a humidity condition in which the inside of the fuel cell stack can avoid a dry state,
Wherein the fourth reference value is a reference value that satisfies a humidity condition in which the interior of the fuel cell stack can avoid the wet state. 16. The method of claim 15,
If the measured temperature difference value is greater than a third reference value, the circulating flow rate of the air-cooling refrigerant supplied to the air-cooling heat exchanger is reduced to raise the supply air temperature in the normal operating condition of the fuel cell stack, Wherein the temperature of the fuel cell stack is lower than that in the normal operating condition of the fuel cell stack by increasing the circulating flow rate of the coolant for stack cooling circulated in the stack. 18. The method of claim 16,
Wherein the number of revolutions of the air-cooling circulation pump for circulating the air-cooling refrigerant to the air-cooling heat exchanger is reduced when the measurement temperature difference is larger than the third reference value, The circulation flow rate of the refrigerant for cooling the air is decreased, the temperature of the supply air is raised through the circulation flow rate reduction of the air-
The circulation flow rate of the coolant for stack cooling is increased by increasing the number of revolutions of the coolant circulation pump for stack cooling that circulates the coolant for stack cooling to the fuel cell stack when the fuel cell stack is in a normal operation condition of the fuel cell stack, Wherein the temperature of the fuel cell stack is reduced by increasing the circulation flow rate of the refrigerant. 18. The method of claim 17,
Wherein when the first measured temperature is higher than the first reference value after the temperature of the supplied air is raised, the number of revolutions of the circulating pump for cooling the air is adjusted to the normal operating condition of the fuel cell stack,
Wherein the first reference value is a reference temperature that satisfies a humidity condition capable of avoiding a dry state of the fuel cell stack. 16. The method of claim 15,
Wherein the circulation flow rate of the air cooling refrigerant supplied to the air cooling heat exchanger is increased to cool the supply air more than the normal operating condition of the fuel cell stack when the measured temperature difference value is smaller than the fourth reference value, Wherein the circulating flow rate of the coolant for cooling the stack circulating in the cell stack is reduced to increase the temperature of the fuel cell stack at the time of normal operation of the fuel cell stack. The method of claim 19,
Wherein when the measured temperature difference value is smaller than the fourth reference value, the number of revolutions of the air-cooling circulation pump for circulating the air-cooling refrigerant to the air-cooling heat exchanger is increased than when the fuel- The circulation flow rate of the cooling refrigerant is increased, the supply air is cooled through the circulation flow rate increase of the air cooling refrigerant,
The circulation flow rate of the coolant for stack cooling is reduced by reducing the number of revolutions of the coolant circulation pump for stack cooling that circulates the coolant for stack cooling to the fuel cell stack when the fuel cell stack is in a normal operating condition of the fuel cell stack, Wherein the temperature of the fuel cell stack is increased by reducing the circulating flow rate of the refrigerant. The method of claim 20,
If the first measured temperature is lower than the second reference value after the cooling of the supply air, maintains the number of revolutions of the coolant circulation pump for air cooling according to normal operating conditions of the fuel cell stack,
Wherein the second reference value is a reference temperature that satisfies a humidity condition capable of avoiding the wet state of the fuel cell stack.
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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009117066A (en) 2007-11-02 2009-05-28 Nissan Motor Co Ltd Fuel cell system and control method of fuel cell system

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009117066A (en) 2007-11-02 2009-05-28 Nissan Motor Co Ltd Fuel cell system and control method of fuel cell system

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