JP2015201408A - fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve processing efficiency in removal of residual water by reflecting a determination about whether the further removal of the residual water is required with effects of the removal of the residual water in real time in a fuel cell system capable of estimating the quantity of the residual water in a gas flow passage and removing the residual water.SOLUTION: The fuel cell system includes a fuel cell including the gas flow passage and a removal section for removing the residual water being residual within the gas flow passage. The removal section estimates the quantity of the residual water on the basis of at least either a voltage change rate of the fuel cell during the removal of the residual water or a pressure loss change rate of gas before and after fuel cell passage during the removal of the residual water and determines whether the further removal of the residual water is required in accordance with the estimated quantity of the residual water.

Description

  The present invention relates to a fuel cell system.

  The fuel cell includes a single cell comprising a membrane electrode assembly (MEA, (Membrane Electrode Assembly) in which a solid polymer electrolyte membrane is sandwiched between an anode electrode and a cathode electrode, and separators disposed on both sides of the MEA. A fuel gas flow path is formed between the anode electrode and one separator, and an oxidizing gas flow path is formed between the cathode electrode and another separator. By supplying hydrogen gas as the fuel gas to the channel and supplying air as the oxidizing gas to the oxidizing gas channel, the fuel cell can generate electric power by an electrochemical reaction between hydrogen and oxygen.

  In such a fuel cell, water generated in the electrochemical reaction may remain in the fuel gas channel or the oxidizing gas channel (hereinafter also referred to as “residual water”). Residual water hinders fuel gas supply and oxidant gas supply to the MEA, causing a problem of reducing the power generation performance of the fuel cell. Further, in a sub-freezing environment, there is a problem that the power generation area of the MEA is reduced due to freezing of residual water, and the power generation performance of the fuel cell is reduced. In order to solve such a problem, a fuel cell system is known that includes a predicting unit that predicts the amount of residual water in the fuel gas channel and the oxidizing gas channel, and a scavenging unit that removes residual water. (For example, patent document 1).

JP 2008-010347 A JP 2013-191370 A JP 2013-196778 A JP 2007-280844 A JP 2004-343473 A JP 2010-044869 A

  The prediction means described in Patent Document 1 is not assumed for “prediction of the amount of residual water” during the removal of residual water by the scavenging means. For this reason, in the technique described in Patent Document 1, the effect of removing residual water by the scavenging means cannot be reflected in real time in the determination of whether or not further residual water needs to be removed. There was a problem of being bad. Moreover, in the technique of patent documents 2-6, it is not assumed about estimating the quantity of residual water.

  Therefore, in a fuel cell system that can estimate the amount of residual water in the gas flow path and remove residual water, the effect of residual water removal can be determined in real time in determining whether further residual water needs to be removed. The purpose is to improve the treatment efficiency of residual water removal. In addition, in the prior art, improvement in power generation performance, reliability, durability, improvement in manufacturing efficiency, ease of manufacturing, cost reduction, and the like of the fuel cell system have been desired.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

(1) According to one aspect of the present invention, a fuel cell system is provided. The fuel cell system includes: a fuel cell including a gas flow path; and a removal unit for removing residual water remaining in the gas flow path; the removal part; Estimating the amount of the residual water based on at least one of the rate of change of the voltage of the fuel cell in FIG. 5 and the rate of change of the pressure loss of the gas flow path during the removal of the residual water; It is determined whether further removal of the residual water is necessary according to the amount of the residual water. According to the fuel cell system of this aspect, the removing unit includes at least one of a voltage change rate of the fuel cell during the removal of residual water and a change rate of the pressure loss of the gas flow path during the removal of residual water. On the other hand, the amount of residual water during the removal of residual water can be estimated in real time. Further, the removal unit determines whether or not further residual water needs to be removed according to the estimated amount of residual water. It can be reflected in judgment in real time. As a result, in the fuel cell system, it is possible to improve the processing efficiency of the residual water removal.

  The present invention can be realized in various forms. For example, it is realizable with aspects, such as a fuel cell system, a control method of a fuel cell system, and a mobile object provided with them. In addition, the present invention does not necessarily have all the various features described above, and may be configured by omitting some of them.

It is explanatory drawing which shows schematic structure of the fuel cell system 10 as one Embodiment of this invention. It is a flowchart which shows the procedure of a residual water removal process. It is explanatory drawing for demonstrating step S12 of a residual water removal process. It is explanatory drawing for demonstrating the relationship between the voltage change rate of the fuel cell 20, and the effect of the removal of residual water. It is a flowchart which shows the procedure of a residual water removal process (modification 1). FIG. 6 is an explanatory diagram for explaining a relationship between an anode pressure loss change rate of the fuel cell 20 and an effect of removing residual water. It is a flowchart which shows the procedure of a residual water removal process (modification 2).

  Next, embodiments of the present invention will be described in the following order based on examples.

A. Embodiment:
A-1. Configuration of fuel cell system:
FIG. 1 is an explanatory diagram showing a schematic configuration of a fuel cell system 10 as an embodiment of the present invention. The fuel cell system 10 is connected to a motor or the like for applying a propulsive force to a vehicle such as an automobile and supplies electric power to the vehicle. The fuel cell system 10 includes a fuel cell 20, a control unit 110, a hydrogen supply unit 120, an oxygen supply unit 130, and a cooling unit 140.

The fuel cell 20 is a polymer electrolyte fuel cell that generates electricity by an electrochemical reaction between hydrogen and oxygen. In the present embodiment, the reaction gas supplied to the fuel cell 20 includes a fuel gas containing hydrogen (H ₂ ) (hereinafter also referred to as “hydrogen gas”) and an oxidizing gas containing oxygen (O ₂ ) ( Hereinafter referred to as “air”). The hydrogen gas supplied to the fuel cell 20 decreases in hydrogen concentration as the electrochemical reaction between hydrogen and oxygen proceeds, and is discharged outside the fuel cell 20 as an anode off-gas. The air supplied to the fuel cell 20 decreases in oxygen concentration as the electrochemical reaction between hydrogen and oxygen proceeds, and is discharged outside the fuel cell 20 as cathode offgas.

  The fuel cell 20 has a stack structure in which a plurality of single cells are stacked in series electrically. The single cell includes a membrane electrode assembly (MEA), a gas diffusion layer, and a separator.

  The MEA has a configuration in which an electrode catalyst layer composed of an anode electrode and a cathode electrode is laminated on both surfaces of an electrolyte membrane. The electrolyte membrane is formed of a proton conductor having proton conductivity (for example, a perfluorosulfonic acid ion exchange membrane using an ionomer resin). The anode electrode and the cathode electrode are materials having gas permeability, conductivity and water repellency (for example, platinum containing platinum) in addition to a catalytic function for promoting an electrochemical reaction between hydrogen and oxygen performed through an electrolyte membrane. The material is formed by mixing an ionomer resin, which is a proton conductor, on a carbon support carrying a catalyst.

  The gas diffusion layers are disposed on both sides of the MEA. The gas diffusion layer is formed of a material having gas permeability, conductivity, and water repellency (for example, a material obtained by impregnating a carbon cloth or carbon paper with a water repellent resin). The separator is disposed on both sides of the gas diffusion layer. The separator disposed on the anode electrode side forms an anode flow channel for flowing hydrogen gas on the anode side surface of the MEA. The separator disposed on the cathode electrode side forms a cathode flow channel for flowing air on the cathode side surface of the MEA. The separator is formed of a material (for example, stainless steel, carbon resin, conductive ceramics) having conductivity in addition to sufficient strength and gas impermeability for flowing hydrogen gas or air.

  The control unit 110 includes a PCU (Power Control Unit) 111, a current measurement unit 112, and a voltage measurement unit 113. The PCU 111 includes a boost converter (not shown) and an inverter, and has a function of controlling the output of the fuel cell 20. Further, the PCU 111 executes a residual water removal process described later. The residual water removal process of the present embodiment is a process for removing water such as generated water remaining in the anode channel (hereinafter also referred to as “residual water”). Here, the “generated water” means water generated during the electrochemical reaction of the fuel cell 20. The current measuring unit 112 measures the current value output from the fuel cell 20 and transmits the measurement result to the PCU 111. The voltage measurement unit 113 measures the voltage value output from the fuel cell 20 and transmits the measurement result to the PCU 111. The control unit 110 functions as a “removal unit”.

  The hydrogen supply unit 120 has a function of supplying hydrogen gas to the fuel cell 20 based on an instruction from the PCU 111. The hydrogen supply unit 120 includes an injector 121, a hydrogen pump 122, a supply path side pressure gauge 123, an anode flow path 124, a discharge path side pressure gauge 125, and a shut valve 126. The injector 121 is connected to a hydrogen tank in which hydrogen gas is stored, and functions as an adjustment valve for adjusting the amount of hydrogen gas supplied to the fuel cell 20. The hydrogen pump 122 functions as power for sending hydrogen gas to the fuel cell 20. The supply path pressure gauge 123 measures the pressure in the supply path of hydrogen gas to the fuel cell 20. The anode flow path 124 is a flow path for flowing hydrogen gas to the anode side surface of the MEA of the fuel cell 20. The discharge path side pressure gauge 125 measures the pressure in the discharge path of the anode off gas from the fuel cell 20. The shut valve 126 functions as an adjustment valve for adjusting the discharge amount when discharging the anode off gas and water vapor to the outside.

  The oxygen supply unit 130 has a function of supplying air to the fuel cell 20 based on an instruction from the PCU 111. The oxygen supply unit 130 includes a flow meter 131, an ACP 132, a cathode channel 134, a discharge channel side pressure gauge 135, and a pressure regulating valve 136. The flow meter 131 measures the flow rate of air supplied to the fuel cell 20. The ACP 132 functions as power for sending air to the fuel cell 20. The cathode channel 134 is a channel for flowing air to the cathode side surface of the MEA of the fuel cell 20. The discharge path side pressure gauge 135 measures the pressure in the discharge path of the cathode off gas from the fuel cell 20. The pressure regulating valve 136 functions as an adjustment valve for adjusting the discharge amount when discharging the cathode off gas and water vapor to the outside.

  The cooling unit 140 cools the fuel cell 20 by dissipating the heat of the cooling water into the atmosphere while circulating the cooling water (antifreeze) as a refrigerant between the inside of the fuel cell 20 and the radiator 141. The cooling unit 140 includes a radiator 141, a water pump 142, and a water temperature gauge 143. The radiator 141 is a device for dissipating heat of the cooling water into the atmosphere. The water pump 142 functions as power for circulating the cooling water in the flow path between the fuel cell 20 and the radiator 141. The water temperature meter 143 measures the temperature of the cooling water.

  In the present embodiment, the anode channel 124 and the cathode channel 134 are collectively referred to simply as “gas channel”.

A-2. Residual water removal treatment:
FIG. 2 is a flowchart showing the procedure of the residual water removal process. The residual water removal process of this embodiment is a process for removing residual water remaining in the anode flow path 124 (FIG. 1), and is executed by the control unit 110. The residual water removal process can be executed at an arbitrary timing. For example, the residual water removal process may be executed continuously during power generation of the fuel cell 20, may be executed at the start and end of power generation of the fuel cell 20, or is periodically performed during power generation of the fuel cell 20. May be executed automatically. Moreover, you may perform by the instruction | indication of the user of the vehicle carrying the fuel cell 20. FIG.

  In step S10, the PCU 111 sets “0” to a variable n (n is an integer of 0 or more) used in the residual water removal process. Note that the variable n is used to calculate the voltage change rate.

  FIG. 3 is an explanatory diagram for explaining step S12 of the residual water removal process. In step S12 of the residual water removal process (FIG. 2), the PCU 111 starts pulsation on the anode (hydrogen electrode) side. Specifically, the PCU 111 periodically increases or decreases the pressure (KPa) of the hydrogen gas supplied to the anode flow path 124 by adjusting the opening degree of the injector 121 and the driving force of the hydrogen pump 122 ( FIG. 3). As the pressure of the hydrogen gas supplied to the anode flow path 124 increases or decreases as shown in FIG. 3, the residual water stagnating in the anode flow path 124 is promoted to the discharge path side, and the residual water is shut off. It is removed to the outside through the valve 126. Instead of periodically increasing or decreasing the pressure of the hydrogen gas, the PCU 111 periodically changes the flow rate (L / min) of the hydrogen gas supplied to the anode flow path 124 or the opening degree (%) of the injector 121. It may be increased or decreased automatically. Even if it does in this way, the same effect can be acquired if the pressure of hydrogen gas is increased or decreased periodically.

In step S14 of the residual water removal process (FIG. 2), the PCU 111 acquires the voltage change (V _n , ΔV _{n + 1} ) of the fuel cell 20 over time. Specifically, the PCU 111 adjusts the magnitude (ΔV _n , ΔV) of the change in the voltage value obtained by the voltage measurement unit 113 before and after the hydrogen gas pressure increase / decrease in accordance with the hydrogen gas pressure increase / decrease period in step S12. _{n + 1} ).

In step S16, the PCU 111 calculates a voltage change rate (ΔV _{n + 1} / ΔV _n ) using the voltage change with time acquired in step S14.

In step S18, the PCU 111 determines whether or not the calculated voltage change rate is greater than a predetermined threshold value α (ΔV _{n + 1} / ΔV _n > α). The predetermined threshold value α can be arbitrarily determined.

  When the voltage change rate is equal to or less than the predetermined threshold value α (step S18: NO), the PCU 111 counts up n in step S20. Thereafter, the PCU 111 shifts the process to step S14 and repeats the processes of steps S14 to S20 while continuing the pulsation on the anode side. As a result, the PCU 111 can continue the pulsation on the anode side until the voltage change rate becomes larger than the predetermined threshold value α, and remove the residual water stagnating in the anode flow path 124.

  When the voltage change rate is larger than the predetermined threshold α (step S18: YES), the PCU 111 shifts the process to step S22. In step S22, the PCU 111 ends the anode side pulsation by adjusting the opening degree of the injector 121 and the driving force of the hydrogen pump 122. Thereafter, the PCU 111 ends the process.

FIG. 4 is an explanatory diagram for explaining the relationship between the voltage change rate of the fuel cell 20 and the effect of removing residual water. In FIG. 4, the vertical axis represents voltage change (ΔV) and the horizontal axis represents time (sec). The horizontal axis in FIG. 4 corresponds to FIG. As the residual water stagnating in the anode flow path 124 is removed in step S12 of the residual water removal process (FIG. 2), the supply state of hydrogen gas to the MEA becomes good, and the power generation performance of the fuel cell 20 Gradually improve. As the power generation performance of the fuel cell 20 is improved, fluctuations in the output voltage of the fuel cell 20 are eliminated, and the voltage change ΔV is reduced. Therefore, the voltage change ΔV ₁ acquired at the second time is smaller than the voltage change ΔV ₀ acquired at the first time in FIG. 4, and the voltage acquired at the third time than the voltage change ΔV ₁ acquired at the second time. The change ΔV ₂ is smaller.

Therefore, when the voltage change rate (ΔV _{n + 1} / ΔV _n ) between the nth voltage change ΔV _n and the (n + 1) th voltage change ΔV _{n + 1} is larger than the predetermined threshold value α, in other words, , When the amount of change between the nth voltage change and the (n + 1) th voltage change is sufficiently small, the amount of residual water stagnating in the anode flow path 124 is further increased. It can be estimated that it has been reduced to the extent that removal is not required. Therefore, the PCU 111 determines that further residual water removal is unnecessary and ends the residual water removal process (FIG. 2, step S22). On the other hand, when the voltage change rate (ΔV _{n + 1} / ΔV _n ) between the n- _th voltage change ΔV _n and the (n + 1) th voltage change ΔV _{n + 1} is equal to or less than a predetermined threshold value α, in other words, n When the amount of change between the first voltage change and the (n + 1) th voltage change is still large, it can be estimated that a certain amount of residual water still exists in the anode flow path 124. Therefore, the PCU 111 determines that further residual water needs to be removed, and continues the process of step S12 in FIG.

  In the above embodiment, the PCU 111 estimates the amount of residual water stagnating in the anode channel 124 from the voltage change rate of the fuel cell 20, and the pressure or flow rate of the hydrogen gas supplied to the anode channel 124. The residual water stagnating in the anode flow path 124 is removed by increasing / decreasing. This is because in the fuel cell 20, there is a remarkable occurrence of a residual water pool in the anode channel 124, particularly in a low temperature environment. As a modification of the above embodiment, the PCU 111 estimates the amount of residual water stagnating in the anode channel 124 and the cathode channel 134 from the voltage change rate of the fuel cell 20, and is supplied to the anode channel 124. Residual water stagnating in the anode channel 124 and the cathode channel 134 by increasing or decreasing both the pressure or flow rate of hydrogen gas and the pressure or flow rate of air supplied to the cathode channel 134 May be removed. Further, the PCU 111 estimates the amount of residual water stagnating in the cathode channel 134 from the voltage change rate of the fuel cell 20, and increases or decreases the pressure or flow rate of the air supplied to the cathode channel 134. The residual water stagnating in the cathode channel 134 may be removed.

As described above, according to the residual water removal process of the present embodiment, the PCU 111 of the control unit 110 (removal unit) causes the voltage change rate (ΔV _{n + 1} / ΔV _n ) of the fuel cell 20 during the removal of residual water. Based on the above, the amount of residual water during the removal of residual water can be estimated in real time. In addition, the PCU 111 of the control unit 110 determines whether or not further residual water needs to be removed according to the estimated amount of residual water. It can be reflected in real time in the determination of whether or not. As a result, in the fuel cell system 10, it is possible to improve the processing efficiency of the residual water removal.

A-3. Residual water removal treatment (deformation 1):
In the fuel cell system 10 of the present embodiment, the residual water removal process shown in FIG. 5 may be executed instead of the residual water removal process shown in FIG. In the residual water removal process of FIG. 5, the PCU 111 replaces the voltage change rate of the fuel cell 20 with the change rate of the pressure loss in the gas flow path of the fuel cell 20 (hereinafter also simply referred to as “pressure loss change rate”). Based on the above, the amount of residual water is estimated.

  FIG. 5 is a flowchart showing a procedure of residual water removal processing (modification 1). The residual water removal process of this modification is a process for removing residual water remaining in the anode channel 124 (FIG. 1), as in FIG. 2, and is executed by the control unit 110. The residual water removal process of this modification can be executed at an arbitrary timing.

  In step S30, the PCU 111 sets “0” to a variable n (n is an integer of 0 or more) used in the residual water removal process. The variable n is used for calculating the pressure loss change rate.

  In step S32, the PCU 111 starts pulsation on the anode side. Details are the same as step S12 in FIG.

In step S <b> 34, the PCU 111 acquires the pressure loss (P _n , P _{n + 1} ) with time in the anode side flow path of the fuel cell 20. The pressure loss in the anode side channel (hereinafter also referred to as “anode pressure loss”) is a pressure loss that occurs when hydrogen gas passes through the anode channel 124 of the fuel cell 20, and is provided in the hydrogen supply unit 120. This is represented by the difference between the detected value of the supply path side pressure gauge 123 and the detected value of the discharge path pressure gauge 125. In step S34, the PCU 111 acquires the anode pressure loss (P _n , P _{n + 1} ) in accordance with the hydrogen gas pressure increase / decrease period in step S32.

In step S36, the PCU 111 uses the anode pressure loss with time acquired in step S34 to change the anode pressure loss rate (P _n −P _{n + 1} / P _n ), which is the rate of change in pressure loss in the anode side flow path. Calculate

In step S38, the PCU 111 determines whether or not the calculated anode pressure loss change rate is smaller than a predetermined threshold value β (P _n −P _{n + 1} / P _n <β). The predetermined threshold β can be arbitrarily determined.

  When the anode pressure loss change rate is equal to or higher than the predetermined threshold β (step S38: NO), the PCU 111 counts up n in step S40. Thereafter, the PCU 111 shifts the process to step S34 and repeats the processes of steps S34 to S40 while continuing the pulsation on the anode side. Thus, the PCU 111 can continue the pulsation on the anode side and remove the remaining water stagnating in the anode flow path 124 until the anode pressure loss change rate becomes smaller than the predetermined threshold value β.

  When the anode pressure loss change rate is smaller than the predetermined threshold β (step S38: YES), the PCU 111 shifts the process to step S42. In step S42, the PCU 111 ends the anode side pulsation by adjusting the opening degree of the injector 121 and the driving force of the hydrogen pump 122. Thereafter, the PCU 111 ends the process.

FIG. 6 is an explanatory diagram for explaining the relationship between the anode pressure loss change rate of the fuel cell 20 and the effect of removing the residual water. In FIG. 6, the vertical axis represents anode pressure loss (kPa) and the horizontal axis represents time (sec). The horizontal axis in FIG. 6 corresponds to FIG. As the residual water stagnating in the anode flow path 124 is removed in step S32 of the residual water removal process (FIG. 5), the supply state of hydrogen gas to the MEA becomes good. As the supply state of hydrogen gas improves, the anode pressure loss P (pressure loss generated when hydrogen gas passes through the anode flow path 124 of the fuel cell 20) gradually approaches a constant value. Therefore, obtaining the third anode pressure drop P ₁ acquired for the first time and than the difference (P ₁ -P ₂₎ between the anode pressure loss P ₂ obtained for the second time, the anode pressure loss P ₂ obtained for the second time as in FIG. 5 The difference (P ₂ −P ₃ ) from the anode pressure loss P ₃ is smaller.

Therefore, the anode pressure loss change rate (P _n −P _{n + 1} / P _n ) between the nth anode pressure loss P _n and the n + 1th anode pressure loss P _{n + 1} is smaller than the predetermined threshold value β. In other words, in other words, when the amount of change between the nth anode pressure loss and the n + 1th anode pressure loss is sufficiently small, the amount of residual water stagnating in the anode flow path 124 is It can be assumed that it has been reduced to the extent that no further residual water removal is required. Therefore, the PCU 111 determines that further residual water removal is unnecessary and ends the residual water removal process (FIG. 5, step S42). On the other hand, the n-th anode pressure loss P _n, if (n + 1) th and the anode pressure loss P _{n + 1,} the anode pressure loss rate of change _{(P n -P n + 1 /} P n) is not less than a predetermined threshold value beta, In other words, when the amount of change between the nth anode pressure loss and the (n + 1) th anode pressure loss is still large, it can be estimated that a certain amount of residual water still exists in the anode flow path 124. . Therefore, the PCU 111 determines that further residual water needs to be removed, and continues the process of step S32 in FIG.

  In this modification as well, the amount of residual water stagnating in the cathode channel 134 is determined by using the rate of change in pressure loss in the cathode side channel instead of or together with the anode channel 124. It may be estimated, or residual water stagnating in the cathode channel 134 may be removed.

As described above, according to the residual water removal process of this modification, the PCU 111 of the control unit 110 (removal unit) causes the pressure loss of the gas flow path (the anode flow path 124 and the cathode flow path 134) during the removal of residual water. Based on the rate of change (P _n −P _{n + 1} / P _n ), the amount of residual water during the removal of residual water can be estimated in real time. In addition, the PCU 111 of the control unit 110 determines whether or not further residual water needs to be removed according to the estimated amount of residual water. It can be reflected in real time in the determination of whether or not. As a result, in the fuel cell system 10, it is possible to improve the processing efficiency of the residual water removal.

A-4. Residual water removal treatment (deformation 2):
In the fuel cell system 10 of the present embodiment, the residual water removal process shown in FIG. 7 may be executed instead of the residual water removal process shown in FIG. In the residual water removal process of FIG. 7, the PCU 111 replaces the voltage change rate of the fuel cell 20 with the amount of residual water based on the rate of change of pressure loss (pressure loss change rate) in the gas flow path of the fuel cell 20. Is estimated.

FIG. 7 is a flowchart showing the procedure of the residual water removal process (modification 2). The difference from Modification 2 shown in FIG. 5 is that step S50 is provided instead of step S36, and step S52 is provided instead of step S38. In step S50, the PCU 111 obtains the anode pressure loss change rate by ( _{Pn + 1} / _Pn ) using the _nth anode pressure loss _Pn and the (n + 1) th anode pressure loss _{Pn + 1} . In step S52, the PCU 111 performs a comparison using a predetermined threshold value γ instead of the predetermined threshold value β in accordance with a different method of obtaining the anode pressure loss change rate. Other details are the same as those of the second modification shown in FIG.

  As described above, the same effect as that of the modification 2 shown in FIG. 5 can be obtained by the residual water removing process of the present modification.

B. Variation:
In addition, this invention is not restricted to said Example and embodiment, A various structure can be taken in the range which does not deviate from the summary. For example, a function realized by software may be realized by hardware. In addition, the following modifications are possible.

・ Modification 1:
In the said Example, it illustrated about the structure of the fuel cell system. However, these configurations can be arbitrarily determined without departing from the scope of the present invention.

  For example, various types of fuel cells can be used as the fuel cell, and the fuel cell is not limited to a solid polymer fuel cell. Specifically, for example, a molten carbonate fuel cell may be used.

  For example, the hydrogen supply unit is configured to supply hydrogen from a tank that compresses and stores hydrogen. However, for example, the hydrogen supply unit may be a device that supplies hydrogen from a hydrogen storage alloy that stores hydrogen, or a natural supply unit. An apparatus that supplies hydrogen from a reformer that takes out hydrogen by reforming a hydrocarbon fuel such as gas, methanol, or gasoline may be used.

Modification 2
In the said embodiment, an example of the residual water removal process was shown. However, the procedure of the residual water removal process is merely an example, and various modifications can be made. For example, some steps may be omitted, and other steps may be added. Further, the order of the steps to be executed may be changed.

  For example, the amount of residual water is estimated (step S18 in FIG. 2, step S38 in FIG. 5, FIG. 7) before starting the pulsation on the anode side (before execution of step S12 in FIG. 2 and step S32 in FIGS. 5 and 7). Step S52). If it does so, when it is not necessary to remove residual water, it can suppress that the pulsation by the side of an anode is started, and the efficiency of a residual water removal process can be improved further.

  For example, in Step S12 of FIG. 2 and Step S32 of FIGS. 5 and 7, instead of pulsation on the anode side (increase / decrease in pressure of hydrogen gas supplied to the anode flow path, increase / decrease in flow rate, increase / decrease in injector opening). Other methods may be used to remove residual water.

・ Modification 3:
In the above embodiment, the fuel cell system is a system mounted on a vehicle that travels using the power generated by the fuel cell, but other modes can also be adopted. For example, the fuel cell system may be applied to a system installed as a power source for a house or facility, or may be applied to a system mounted as a power source on an electromechanical device that operates by electricity.

DESCRIPTION OF SYMBOLS 10 ... Fuel cell system 20 ... Fuel cell 110 ... Control part 112 ... Current measurement part 113 ... Voltage measurement part 120 ... Hydrogen supply part 121 ... Injector 122 ... Hydrogen pump 123 ... Supply path side pressure gauge 124 ... Anode flow path 125 ... Discharge path side Pressure gauge 126 ... Shut valve 130 ... Oxygen supply part 131 ... Flow meter 134 ... Cathode flow path 135 ... Discharge path side pressure gauge 136 ... Pressure regulating valve 140 ... Cooling part 141 ... Radiator 142 ... Water pump 143 ... Water temperature gauge n ... Variable ΔVn ... Voltage change Pn ... Anode pressure loss

Claims (1)

A fuel cell system,
A fuel cell comprising a gas flow path;
A removal section for removing residual water remaining in the gas flow path;
With
The removing unit is
Based on at least one of the voltage change rate of the fuel cell during the removal of the residual water and the change rate of the pressure loss of the gas flow path during the removal of the residual water, the residual water Estimate the quantity,
A fuel cell system that determines whether or not further removal of the residual water is necessary according to the estimated amount of the residual water.

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