DE102015223039A1 - fuel cell - Google Patents

Abstract

Fuel cell (1), in particular a polymer electrolyte fuel cell, with a cathode air leading cathode line (10), a fuel-carrying anode line (20), and a purge line (30) connecting the anode line (20) with the cathode line (10) wherein the purge line (10) is so connected to the cathode line (10), depending on the operating state of the fuel cell (1) a gasified purged mixture optionally to the fuel cell (1), at least partially past the fuel cell (1) or essentially to pass the fuel cell (1) over.

Description

The present invention relates to a fuel cell, in particular a polymer electrolyte fuel cell, according to claim 1 and a method for operating a fuel cell, in particular a polymer electrolyte fuel cell, according to claim 5.

State of the art

Fuel cells are known as electrical energy sources. Compared with internal combustion engines in particular, electrical energy sources have the advantage that they normally do not produce any, in particular harmful exhaust gases during operation. At the beginning of the operation of the fuel cells, a deliberate purge of an anode, a so-called purge process, is instructed to free the anode of air and to fill it with hydrogen. As a result, the purged gas mixture, which may contain air and hydrogen, pass into a cathode conduit. In the starting case, the hydrogen-containing purged gas mixture can bring air to a cathode of the fuel cell. In the starting case, however, air in the cathode is not desirable. In normal operation can also be gepurgt, wherein the purged gas mixture may contain amounts of hydrogen that can not be sufficiently diluted by natural convection and ventilation.

Disclosure of the invention

It is an object of the present invention to provide an improved fuel cell, in particular a polymer electrolyte fuel cell, and a safe method for operating a fuel cell, in particular a polymer electrolyte fuel cell.

The present invention provides a fuel cell, in particular a polymer electrolyte fuel cell, with the features of claim 1 and by a method for operating a fuel cell, in particular a polymer electrolyte fuel cell, with the features of claim 5. This is an improved fuel cell, in particular a Polymer electrolyte fuel cell, and a safe method for operating a fuel cell, in particular a polymer electrolyte fuel cell achieved. In addition, the useful life of the stacks of fuel cells can be significantly increased. Further advantages, features and details of the invention will become apparent from the dependent claims, the description and the drawings. In this case, features and details that are described in connection with the fuel cell according to the invention apply, of course, also in connection with the inventive method and in each case vice versa, so with respect to the disclosure of the individual aspects of the invention always reciprocal reference is or may be.

The invention provides a fuel cell, in particular a polymer electrolyte fuel cell, which is formed with a cathode air leading cathode line, a fuel, hydrogen, leading anode line, and a purge line connecting the anode line to the cathode line, wherein the purge -Leitung is so connected to the cathode line, depending on the operating condition of the fuel cell, a purged gas mixture optionally to the fuel cell, at least partially to the fuel cell over or substantially to pass the fuel cell over. In this case, the fuel cell is also understood to mean a series of a plurality of fuel cells which can be connected in series in a stack or in a so-called "stack". The fuel cell according to the invention can be used for mobile applications, such as in motor vehicles, or for stationary applications, such as in emergency power supply and / or as a generator.

The idea of the invention lies in determining the course of the purged gas mixture in a targeted manner, depending on the operating state of the fuel cell, in order to ensure improved processing and an operating state of proper removal of the purged gas mixture. Depending on the operating state of the fuel cell, different concentrations of the cathode air and / or the fuel and / or the moisture present in the fuel cell are desirable. In order to achieve the desired concentration, the invention provides for ensuring an optimal distribution of the fluids in the fuel cell through the passage of the purged gas mixture.

As a first operating state in the context of the invention, a start operating state of the fuel cell may be mentioned, in which a filling of the anode can take place. In this case, a purge process may be initiated by, for example, opening a purge valve to open the purge line for discharging a gas mixture or fluid in the anode into the cathode line and opening a shut-off valve of a hydrogen tank, to provide fuel, in particular hydrogen, to the fuel cell. In the starting operating state in the filling of the anode, it is desirable that there is no air in a cathode of the fuel cell. This can disadvantageously lead to a degradation of the fuel cell. In particular, in the case of a short-circuit start of the fuel cell, it is important that there is no air in the cathode in order to avoid excessive currents and an effective filling of the anode to enable. According to the invention, it is provided for the starting operating state that the purge line can be connected to the cathode line in such a way that the purged gas mixture essentially bypasses the fuel cell, in particular is transported away in the return line of the cathode line with an exhaust air of the cathode line. Thus, it can advantageously be ensured that the purged gas mixture or fluid does not reach the cathode and that no air penetrates into the cathode. Open circuit voltage conditions can be avoided. Even a short-circuit start can be safely initiated. Thus, advantageously, the anode can be filled effectively and efficiently. The lifetime of the fuel cell can therefore be significantly increased. At the same time measures can also be taken, such. B. turning up a compressor to allow enough air to flow through the cathode conduit and to sufficiently dilute the purged gas mixture. Consequently, it is possible according to the invention that, in the start-up of the fuel cell, the neutralization possibility of the fuel or of the hydrogen is maintained by the cathode air.

In normal operation of the fuel cell, a purge demand may arise, this second operating state in the context of the invention may be referred to as a purge operating state. It is inventively provided that the purge line may be connected to the cathode line such that the purged gas mixture to the fuel cell, in particular in the inlet of the cathode line with a supply air of the cathode line to the fuel cell, is derived. It may be advantageous if the fuel in the purged gas mixture, in particular the hydrogen, can react in the cathode of the fuel cell. This can be particularly advantageous when the fuel, or the hydrogen, reaches concentrations that can not be sufficiently diluted by natural convection and ventilation. This can ensure that critical concentrations of the fuel or hydrogen are confidently avoided.

Furthermore, during normal operation of the fuel cell, a drain demand may arise, wherein this third operating state in the sense of the invention may be referred to as a drain operating state. In the purge line according to the invention may be provided a parallel drain line, which can be performed with a water separator and a water tank. The water balance in the fuel cell is very important and must be reliably maintained at a certain level. In this case, a membrane of the fuel cell must have sufficient but not too much moisture to reliably pass fuel or hydrogen ions from the anodes to the cathode. In order to control the water balance, it may be necessary to drain off excess water. When the water tank is full, the water must be drained. This is done by the drain line. The drain line can converge at the end of the purge line with the purge line. According to the invention, it is provided for the drain operating state that the purge line is connected to the cathode line in such a way that the purged gas mixture, which at the end of the purge line comprises water from the drain line, at least in part, which is determined by the water may be passed past the fuel cell, in particular in the return of the cathode line with the exhaust air of the cathode line is removed. The other part, which may be determined by the fuel or hydrogen and air, may in turn be directed to the fuel cell. In this case, it is advantageous according to the invention that the neutralization possibility of the fuel or of the hydrogen in the cathode is maintained at least in part during normal operation of the fuel cell. Furthermore, it can be advantageously ensured by the invention in normal operation of the fuel cell, that the water can be passed at least partially past the fuel cell to avoid disturbing a water management of the fuel cell. Furthermore, it is advantageous for normal operation that during the drain process, water penetration into the cathode can be reduced, while at the same time maintaining the purge capability.

Furthermore, as a fourth operating state in the context of the invention, a shutdown operating state of the fuel cell may be mentioned, in which all water is discharged from the fuel cell, all residues of reactants are discharged from the fuel cell and / or all lines of the fuel cell are blown free. In this case, it is provided according to the invention that the purge line can be connected to the cathode line in such a way that the purged gas mixture, which comprises water from the drain line at the end of the purge line, is led substantially past the fuel cell, in particular in FIG Return of the cathode line with the exhaust air of the cathode line is removed. In this case, advantageously, a water located in the anode, in particular until the water tank is empty, are flushed out, and also the gas mixture in the anode can be transported away, which can happen all the way past the fuel cell. Advantageously, it can be avoided in the meantime that the cathode air flowing past the purge and drain point penetrates into the fuel cell. After emptying the water tank, the shutdown process can continue as usual, in particular, it can be continued with the blowing out of the lines. Thus, the advantage can be achieved that a dry blowing the Fuel cell can be optimally executed. The shutdown operating state can thus be optimized. The shutdown mode can be significantly shortened and its efficiency can be significantly increased. Also water residues can be eliminated in the fuel cell, which is particularly advantageous for a freeze-start.

Furthermore, it can be provided in the context of the invention that the cathode line can have an inlet to the fuel cell and a return from the fuel cell, wherein the inlet and the return via a bypass line with a bypass valve, in particular in the form of a throttle valve, can be connected. It may be advantageous that the bypass valve in the form of a throttle valve have a simple control and can confidently determine the course of the cathode air and / or the purged gas mixture and / or the gedrainten fluid. The bypass line can serve to lead the cathode air, with or without the purged gas mixture and / or a fluid of the drain line containing water, past the cathode. This may be particularly advantageous, especially in the start operating state and / or in the shutdown operating state, when no air is allowed to enter the cathode, let alone the fuel or water. Advantageously, unwanted currents can be avoided by the fuel cell.

Furthermore, it can be provided within the scope of the invention that the purge line can end before the bypass line, in particular within the bypass line. Thereby, the advantage can be achieved that in a simple manner and with simple means, in particular without additional valves or the like, the purge line can be connected to the cathode line such that, depending on the operating condition of the fuel cell, the purged gas mixture optionally to the fuel cell , At least partially past the fuel cell or can be passed substantially past the fuel cell. Alternatively, however, it is also conceivable that an extra valve provided in the purge line may be provided to discharge the purged gas mixture either in the inlet or in the return line of the cathode line.

According to a particular advantage, the purge line may have a drain line. As already described above, the drain line can serve to optimize the water management in the fuel cell and in particular to remove excess water from the anode.

• a) Leiten eines gepurgten Gasgemisches in einem Start-Betriebszustand der Brennstoffzelle im Wesentlichen an der Brennstoffzelle vorbei.

Furthermore, the object according to the invention is achieved by a method for operating a fuel cell, in particular a polymer electrolyte fuel cell, the fuel cell having a cathode air-conducting cathode line, wherein the cathode line has a bypass line between an inlet to and a return from the fuel cell Fuel leading anode line, and a purge line connecting the anode line to the cathode line, the purge line before the bypass line, in particular within the bypass line ends. According to the invention, it is provided for this purpose that the method has at least one step:

• a) passing a purged gas mixture in a start-up operating state of the fuel cell substantially past the fuel cell.

Advantageously, the penetration of the purged gas mixture into the fuel cell, in particular into a cathode of the fuel cell, can thereby be avoided in the starting operating state of the fuel cell. Consequently, according to a particular advantage of the invention, the degradation of the fuel cell can be avoided and the lifetime of the fuel cell can be increased.

• b) Leiten eines gepurgten Gasgemisches in einem Purge-Betriebszustand der Brennstoffzelle zu der Brennstoffzelle.

The method according to the invention can furthermore have at least one further step:

• b) passing a purged gas mixture in a purge operating state of the fuel cell to the fuel cell.

In this case, the normal operation of the fuel cell, in particular the purge operating state of the fuel cell, can be optimized. Advantageously, the fact can be used that during normal operation of the fuel cell air is pumped into the cathode with abundance, and this air can also be used to Abreagieren contained in the purged gas mixture fuel or hydrogen. Thus, it can be advantageously ensured that the superfluous in the fuel cell or in the lines of the fuel cell hydrogen can be confidently eliminated to avoid dangerous accumulations of hydrogen.

• c) Leiten eines Wasser enthaltenen Fluides einer Drain-Leitung der Purge-leitung in einem Drain-Betriebszustand der Brennstoffzelle zu einem Teil an der Brennstoffzelle vorbei und zu einem anderen Teil zu der Brennstoffzelle.

Furthermore, the method according to the invention can have at least one further step:

• c) passing a fluid containing water a drain line of the purge line in a drain operating state of the fuel cell to a part of the fuel cell over and to another part of the fuel cell.

Thus, the normal operation of the fuel cell, in particular the drain operating state of the fuel cell, can advantageously be improved. For this purpose, the invention can provide that the excess water past the fuel cell can be performed in order to avoid a disturbance of a water management of the fuel cell, at the same time the fuel or the hydrogen can reach the cathode of the fuel cell, there to react with oxygen.

• d) Ablassen des gepurgten Gasgemisches der Purge-Leitung und eines Wasser enthaltenen Fluides einer Drain-Leitung der Purge-leitung in einem Shutdown-Betriebszustand der Brennstoffzelle an der Brennstoffzelle vorbei.

Furthermore, it may be advantageous within the scope of the invention if the method can have at least one further step:

• d) discharging the purged gas mixture of the purge line and a water-containing fluid of a drain line of the purge line in a shutdown operating state of the fuel cell to the fuel cell over.

In this case, during the shutdown operating state of the fuel cell, it can advantageously be ensured that the fluid and / or anode water contained in the fuel are reliably removed from the fuel cell.

• e) Freiblasen der Kathodenleitung und/oder der Anodenleitung in einem Shutdown-Betriebszustand der Brennstoffzelle.

Moreover, it can be provided within the scope of the invention that the method can have at least one further step:

• e) blowing the cathode line and / or the anode line in a shutdown operating state of the fuel cell.

This can be achieved in the shutdown operating state of the fuel cell, the advantage that remain after switching off the fuel cell no residues in the fuel cell to avoid unwanted reactions in the fuel cell, and on the other ice formation in the fuel cell at cold temperatures avoid.

According to the invention, it is conceivable that the method steps a) to e) can be carried out in succession and / or the steps b) and c) simultaneously. The advantage lies in the fact that an improved distribution of the purged gas mixture and the cathode air according to the invention in each operating state of the fuel cell can be made possible from the start to the shutdown of the fuel cell. In addition, the normal operation of the fuel cell can be further improved by allowing the purge operation and the drain operation to be carried out together, suggesting the partial passage of the purged gas mixture and the water-containing fluid of the anode water.

Further measures which improve the invention are described in more detail below with the description of the preferred exemplary embodiments of the invention with reference to the figures.

Preferred embodiments

The fuel cell according to the invention and its developments and their advantages and the method according to the invention and its developments and its advantages are explained in more detail below with reference to drawings. Each show schematically:

1 a fuel cell according to the invention,

2 an operating strategy for a starting operating state of the fuel cell according to the invention,

3 an operating strategy for avoiding fuel emissions, in particular hydrogen emissions, for normal operation of the fuel cell according to the invention, in particular for a purge operating state of the fuel cell,

4 a further embodiment of the fuel cell according to the invention,

5 an operating strategy for avoiding the return of liquid water to the fuel cell, after a drain operation for the normal operation of the fuel cell according to the invention, in particular for a drain operating state of the fuel cell, and

6 an operating strategy for a shutdown operating state of the fuel cell according to the invention.

Elements with the same function and mode of action are in the 1 to 6 each provided with the same reference numerals.

The 1 and the 3 each show an embodiment of a fuel cell according to the invention 1 , eg for mobile applications, ie for applications in motor vehicles, or for stationary applications, for example in generators or as an emergency power supply. In the fuel cell 1 takes place a cold combustion of fuel, in particular of hydrogen, by connecting with oxygen, for example. From the normal ambient air instead. The electrical power is via electrical lines 40 tapped and to an electric on-board network 41 , for example in a motor vehicle. This is an anode 2 the fuel cell 1 via an anode lead 20 Fuel, in particular hydrogen, fed during a cathode 4 the fuel cell 1 via a cathode line 10 Cathode air, in particular filtered ambient air, is supplied.

The anode lead 20 has a fuel or a hydrogen tank 21 on which via a valve 22 to reduce the pressure and a shut-off valve 23 For switching off the fuel supply, eg. In case of failure, fuel to the fuel cell 1 provides. The anode lead 20 can also have a throttle 24 exhibit the pressure in the anode lead 20 to control.

A purge pipe 30 is provided, which is the anode lead 20 and the cathode line 10 combines. In the start of the fuel cell 1 can by a corresponding actuation of a purge valve 31 and a recirculation pump 32 or a nipple 32 causes one in the anode 2 the fuel cell 1 located gas mixture in the cathode line 10 is drained to the anode 2 to be cleared of air and filled with fuel, in particular hydrogen. This is called a purge of the fuel cell 1 in the starting case or in the starting operating state of the fuel cell 1 , The 2 gives below an operating strategy for the starting operating state. In addition, the fuel cell may be purged in normal operation to increase the efficiency of the fuel cell, in which case a purge operating condition is discussed. The 3 gives below an operating strategy for the purge operating state.

The cathode line 10 has an inlet according to the invention 11 to the fuel cell 1 , in particular to the cathode 4 the fuel cell 1 , and a return 12 from the fuel cell 1 , especially from the cathode 4 the fuel cell 1 , on. Between the inlet 11 and the return 12 is a bypass line with a bypass valve 13 , z. B. in the form of a throttle valve, provided to the pressure in the cathode line 10 to control. According to the invention, the bypass valve 13 be used to the run of a purged gas mixture according to the 1 and a water containing, purged and gedrained mixture according to the 4 to determine. In the inflow 11 at the entrance of the cathode line 10 is an air filter 19 provided to the ambient air according to the requirements of the fuel cell 1 to filter. At the entrance of the cathode line 10 can also have a temperature sensor 18 be provided for measuring the ambient temperature to check the initial temperature of the ambient air. A compressor 14 or a sucker 14 Ensures that enough air to the cathode 4 the fuel cell 1 arrives. A heat exchanger 15 is provided to the compressed air or cathode air after passage of the compressor 14 to cool to a suitable temperature. A humidifier 16 For example, in the form of a membrane that lets water through but stops the air, ensures that unused cathode air is returned to the cathode 4 is sent. With the help of valves 13 . 17 in the form of throttle valves may be a suitable pressure in the cathode line 10 be set.

The operation of the fuel cell 1 developed heat is transmitted through a cooling fluid leading thermal line 50 dissipated. In the starting event, the thermal line 50 turn serve to the fuel cell 1 to heat to a preferred operating temperature. The thermal line 50 has a cooler 51 and a recirculation pump 52 on to the excess heat during operation of the fuel cell 1 to pick up and remove.

The 2 shows the operating strategy for the starting operating state of the fuel cell 1 , where in step 100 is started with the startup procedure. According to the invention in step 101 First, measures are taken so that the purged gas mixture in the return 12 the cathode line 10 can be drained. For this purpose, on the one hand, the compressor 14 , z. B. up to the maximum speed, turned up to allow optimal dilution of the purged gas mixture, which may contain fuel or hydrogen. And second, this is the bypass valve 13 completely open, to avoid that the purged gas mixture, which may contain air, during the filling of the anode 2 to the cathode 4 arrives. In step 102 is subsequently filled with the anode 2 started by the shut-off valve 23 and the purge valve 31 be opened. In the starting operating state, it is inventively desirable that when filling the anode 2 in the cathode 4 no air is contained, to a degradation of the fuel cell 1 to avoid. In particular, at a short-circuit start of the fuel cell 1 , it is important that in the cathode 4 there is no air to effectively fill the anode 2 to allow and degradation of the fuel cell 1 to prevent. Even without a possibility of neutralization of the hydrogen in the cathode 4 , is made by turning up the compressor 14 ensure that the purged gas mixture is sufficiently diluted. In step 103 it checks if the anode 2 completely filled with fuel or hydrogen. In step 104 can then proceed with the startup procedure.

The 3 shows the operating strategy for the normal operation of the fuel cell 1 in a purge requirement, in which case the purge operating condition is meant. In step 200 normal operation is running as usual. In step 201 a decision is made as to whether a purge requirement exists. If yes, it will be in step 202 the bypass valve 13 completely closed with a normally continuing working compressor 14 , Subsequently, the purge valve 31 be opened for a certain time .DELTA.t and then closed again. Thus, the purged gas mixture in the inlet 11 the cathode line 10 arrive and thus to the cathode 4 the fuel cell 1 where the fuel in the purged gas mixture, in particular the hydrogen, in particular with oxygen of the cathode, can react. Thus, critical concentrations of the fuel or hydrogen in normal operation of the fuel cell 1 be avoided confidently. In step 204 becomes normal operation of the fuel cell 1 continued.

In the embodiment of 4 shows the fuel cell 1 , especially the purge line 30 , also a parallel drain line 33 on, for the removal of excess moisture, in particular excess water, from the fuel cell 1 is provided. The drain line 33 is with a water separator 34 and a water tank 35 executed. The water balance in the fuel cell 1 must be reliably maintained at a certain level. There must be a membrane 3 the fuel cell 1 Have enough moisture to reliably fuel or hydrogen ions from the anode 2 to the cathode 4 the fuel cell 1 pass. Too much water is allowed in the fuel cell 1 also do not collect, hence the functioning of the fuel cell 1 , in particular the membrane 3 not disturbed. The drain line 33 ensures the balanced water management to dissipate the excess water. The drain line 33 can according to the invention at the beginning and at the end with the purge line 30 leak together. In a need, excess water during normal operation of the fuel cell 1 derive, is called according to the invention of a drain operating state. An inventive strategy for the drain operating state is in the 5 shown. In addition, it can shut down the fuel cell at the end of the operation 1 make sense to remove all the water from the fuel cell to no residues in the fuel cell 1 to leave behind and to freeze the residual water in the fuel cell 1 to avoid. Here, in the sense of the invention, a shutdown operating state of the fuel cell can be used 1 speak. An inventive strategy for the shutdown operating state is in the 6 shown.

The 5 shows the operating strategy in the drain operating state to the excess water during normal operation of the fuel cell 1 derive. In step 200 runs the normal operation, as it also according to the 3 the case may be. In step 205 it is checked if there is a drain demand. If yes, it will be in step 206 at the normal continuing working compressor 14 the bypass valve 13 half open. Subsequently, in step 207 the drain valve 36 opened for a certain time .DELTA.t and then closed again. The purged gas mixture, which at the end of the purge line 30 Water from the drain pipe 33 can then be partly to the fuel cell 1 via the bypass line in the return line 12 the cathode line 10 be drained. At the same time, at least part of the purged gas mixture flows into the inlet 11 the cathode line 10 , As a result, during normal operation of the fuel cell 1 be sure that the water is at least partially connected to the fuel cell 1 is passed. In step 208 becomes normal operation of the fuel cell 1 continued. It is conceivable according to the invention that the operating strategy for the drain operating state according to the 5 and the operating strategy for the purge operating state according to the 3 one after the other or at least partly simultaneously. In this case, it is conceivable that the bypass valve 13 at least in part, in particular half, can be open. Furthermore, it is also conceivable that the bypass valve 13 can be opened to a greater extent when the purge process and the drain process are performed simultaneously.

The 6 shows the operating strategy for the shutdown operating state of the fuel cell 1 in which all the water from the fuel cell 1 is drained. In step 300 is started with the shutdown procedure. In step 301 becomes the compressor 14 turned high and high mass air flow the bypass valve 13 open. Subsequently, in the step 302 the drain valve 36 and the purge valve 31 open. The anode water does not flow to the fuel cell 1 back, but after the pressure drop across the bypass line in the return 12 the cathode line 10 , Meanwhile, it can be advantageously avoided that the purged gas mixture and the liquid being drawn back to the fuel cell 1 arrives. In step 303 we checked if the water tank 35 is empty. After that, in step 304 continued with the shutdown procedure and, for example, a dry blowing of the lines 10 . 13 . 20 . 30 . 33 initiated.

Claims (10)

Fuel cell ( 1 ), in particular a polymer electrolyte fuel cell, with a cathode air leading cathode line ( 10 ), a fuel-carrying anode lead ( 20 ), and a purge line ( 30 ), the anode lead ( 20 ) with the cathode line ( 10 ), characterized in that the purge line ( 30 ) in such a way with the cathode line ( 10 ) is connected, depending on the operating state of the fuel cell ( 1 ) a purged gas mixture optionally to the fuel cell cathode ( 4 ), at least in part on the fuel cell cathode ( 1 ) past or substantially at the fuel cell cathode ( 1 ) to pass by. Fuel cell ( 1 ) according to claim 1, characterized in that the cathode line ( 10 ) an inlet ( 11 ) to the fuel cell ( 1 ) and a return ( 12 ) from the fuel cell ( 1 ), wherein the feed ( 11 ) and the return ( 12 ) via a bypass line with a bypass valve ( 13 ), in particular in the form of a throttle valve, are connected. Fuel cell ( 1 ) according to claim 1 or 2, characterized in that the purge line ( 30 ) in front of the bypass line, especially within the bypass line, ends. Fuel cell ( 1 ) according to one of the preceding claims, characterized in that the purge line ( 30 ) a drain line ( 33 ) having. Method for operating a fuel cell ( 1 ), in particular a polymer electrolyte fuel cell, with a cathode air leading cathode line ( 10 ), wherein the cathode line ( 10 ) between an inlet ( 11 ) to and a return ( 12 ) from the fuel cell ( 1 ) has a bypass line, a fuel-carrying anode lead ( 20 ), and a purge line ( 30 ), the anode lead ( 20 ) with the cathode line ( 10 ), whereby the purge line ( 30 ) in front of the bypass line, in particular within the bypass line, ends, characterized in that the method comprises at least one step: a) passing a purged gas mixture in a starting operating state of the fuel cell ( 1 ) substantially at the fuel cell ( 1 ) past. A method according to claim 5, characterized in that the method comprises at least one further step: b) passing a purged gas mixture in a purge operating state of the fuel cell ( 1 ) to the fuel cell ( 1 ). A method according to claim 5 or 6, characterized in that the method comprises at least one further step: c) passing a water-containing fluid of a drain line ( 33 ) in the purge line ( 30 ) in a drain operating state of the fuel cell ( 1 ) to a part of the fuel cell ( 1 ) over and to another part to the fuel cell ( 1 ). Method according to one of claims 5 to 7, characterized in that the method comprises at least one further step: d) blowing the cathode line ( 10 ) and / or the anode line ( 20 ) in a shutdown operating state of the fuel cell ( 1 ). Method according to one of claims 5 to 8, characterized in that the method comprises at least one further step: e) discharging the purged gas mixture of the purge line ( 30 ) and a water-containing fluid of a drain line ( 31 ) in the purge line ( 30 ) in a shutdown operating state of the fuel cell ( 1 ) substantially at the fuel cell ( 1 ) past. Method according to one of claims 5 to 9, characterized in that the method by a fuel cell ( 1 ) is carried out according to one of claims 1 to 5, and that in particular the steps a) to e) are carried out successively and / or the steps b) and c) simultaneously.

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