JP2008091329A - Method for evaluating durability of unit cell, device for evaluating durability, program for evaluating durability, and unit cell of fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily evaluate the durability of a unit cell of a fuel cell by stress according to a moisture distribution of a polymer electrolyte membrane. <P>SOLUTION: This method for evaluating, in an information processor, durability of the unit cell of a fuel cell composed by including a polymer electrolyte membrane and the like includes: a reception step S101 of receiving input of a parameter; model creation steps S02 and S03 of creating a finite element model of the unit cell based on the parameter; a moisture distribution calculation step S04 calculating a moisture distribution based on a boundary condition of the moisture distribution by a finite element method; a strain-stress calculation step S05 calculating strain and stress from the moisture distribution, a water absorption line expansion coefficient and an elastic modulus; an equivalent stress calculation step S06 calculating equivalent stress from the stress; evaluation value derivation steps S07 and S08 deriving an evaluation value for evaluating the durability of the unit cell from the equivalent stress; and an output step S09 outputting the evaluation value. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a single cell durability evaluation method, a durability evaluation apparatus, a durability evaluation program, and a fuel cell single cell for evaluating the durability of a single cell of a fuel cell.

  The polymer electrolyte fuel cell is a clean next-generation fuel cell that uses only water as a by-product by electrochemical reaction between a fuel gas containing hydrogen and an oxidant gas containing oxygen such as air. As a result, research and development is actively underway. For this polymer electrolyte fuel cell, three types of structures of a cylindrical type, a monolith type, and a flat plate type have been proposed. Among these structures, a flat plate type is often adopted for a low temperature operation type polymer electrolyte fuel cell.

  Here, FIG. 1 shows a configuration of a single cell of a general flat-type solid polymer fuel cell. A unit cell 1 of a polymer type fuel cell includes a proton conductive polymer electrolyte membrane 10, plate-like electrodes 11 a and 11 b, and plate-like conductive materials so as to sandwich the polymer electrolyte membrane 10 on both sides. Conductive separators 12a and 12b and annular gas seal materials 13a and 13b are provided.

  In such a polymer electrolyte fuel cell, when the battery is operated, particularly when it is repeatedly operated and stopped for a long time, the polymer electrolyte membrane 10 absorbs water produced as a by-product during the operation of the fuel cell and expands. Stress (hereinafter referred to as water absorption stress) is generated along with expansion / contraction such as drying and contraction when stopped. This stress acts on the junction between the electrodes 11a and 11b and the polymer electrolyte membrane 10. It is speculated that the mechanical deterioration caused by the stress causes damage to the polymer electrolyte membrane 10 (for example, see Patent Document 1 below).

In order to avoid the above-mentioned estimated mechanical deterioration, for example, Patent Document 2 below proposes a method of processing a polymer electrolyte membrane so that the central portion and the outer peripheral portion have different properties. In Patent Document 3 below, a method of changing the rib shape of the gas flow path is proposed. Furthermore, Patent Document 4 below proposes a method of installing an elastic reinforcing material on the outer periphery of the electrode.
JP-A-8-259710 JP 2000-215903 A JP 2005-108777 A JP 2003-68318 A

  However, each of the above-described conventional techniques has a problem in that the manufacturing cost increases due to an increase in the number of manufacturing steps or the number of parts. Furthermore, the method of connecting the improvement of the members constituting the fuel cell to the durability of the fuel cell in this way is to actually manufacture a single cell of the fuel cell and determine the durability through a long-term test, It requires a lot of trial and error. Therefore, a method for evaluating the durability of the fuel cell configuration has been desired. However, a method for evaluating durability by estimating the stress received by the polymer electrolyte membrane accompanying the operation / stop of the fuel cell as described above, in particular, the water absorption stress, has hardly been studied.

  The present invention has been made to solve the above-described problems, and is a single cell durability evaluation method, a durability evaluation apparatus, and durability that can easily evaluate the durability of a single cell of a fuel cell. The purpose is to provide an evaluation program. Furthermore, it aims at providing the single cell of the fuel cell which has high durability by making the evaluation value calculated | required with the said durability evaluation method into a specific range.

  In order to achieve the above object, a durability evaluation method for a single cell according to the present invention includes a polymer electrolyte membrane and two plate-like electrodes provided on both sides of the polymer electrolyte membrane in an information processing device, The durability of a single cell of a fuel cell comprising two plate-like separators each having a groove-like gas flow path for supplying gas to the electrode and a sealing material for sealing the side surface of the electrode. A method for evaluating the durability of a single cell to be evaluated, comprising a reception step for receiving input of parameters relating to the single cell, and a single cell finite element model divided into a plurality of elements based on the parameters received in the reception step The model generation step for generating the finite number generated in the model generation step based on the boundary condition of the moisture distribution included in the parameter received in the reception step Moisture distribution calculation step for calculating the moisture distribution of the polymer electrolyte membrane in the elementary model by the finite element method, the moisture distribution calculated in the moisture distribution calculation step, and the polymer electrolyte membrane included in the parameters accepted in the acceptance step The strain / stress calculation step of calculating the strain and stress of each element of the polymer electrolyte membrane by the finite element method from the water absorption linear expansion coefficient and the elastic modulus of each, and each element calculated in the strain / stress calculation step From the stress at, the equivalent stress calculation step for calculating the equivalent stress at each element concerned, and the evaluation value for evaluating the durability of the single cell from the equivalent stress at each element calculated at the equivalent stress calculation step And the evaluation value derived in the evaluation value deriving step Characterized by comprising an output step of, a.

  The single cell durability evaluation method according to the present invention generates a finite element model related to an evaluation target single cell from input information. In the durability evaluation method, the moisture distribution in the generated finite element model is calculated, and the equivalent stress generated in the polymer electrolyte membrane is calculated based on the moisture distribution. In the durability evaluation method, an evaluation value is derived from the calculated equivalent stress. That is, according to the durability evaluation method for a single cell according to the present invention, the durability of the single cell of the fuel cell can be evaluated in consideration of the stress corresponding to the moisture distribution of the single cell, that is, the water absorption stress. Further, according to the method for evaluating durability of a single cell according to the present invention, evaluation can be performed in an information processing apparatus, and it is not necessary to actually create and evaluate a single cell. Sex can be evaluated.

Further, the inventors of the present application have found that the durability of a single cell can be evaluated by a range in which a stress of a certain level or more is generated in an ineffective power generation region after intensive research. The evaluation value which can evaluate sex was created. That is, in the evaluation value deriving step, the average value S _av of the equivalent stress of the elements in the effective power generation region related to the electric reaction in the polymer electrolyte membrane among the elements for which the equivalent stress is calculated in the equivalent stress calculation step is derived and set. The elements of the ineffective power generation region other than the effective power generation region in the polymer electrolyte membrane in which the equivalent stress is c × S _av or more with respect to one or more coefficient c is extracted, and the total volume of the extracted elements it is desirable to derive the evaluation value by a preset calculation formula from the values of V _z. More specifically, in the evaluation value deriving step, from the values of the total volume V _z , the volume V0 of the polymer electrolyte membrane, the volume V _y of the effective power generation region in the polymer electrolyte membrane, and the thickness d of the polymer electrolyte membrane, The single cell durability evaluation method according to claim 2, wherein α derived from Equation 1 and β derived from Equation 2 are used as evaluation values.

  The coefficient c is preferably 1.2. According to this configuration, more appropriate durability can be evaluated. In addition, said numerical value is a value obtained empirically by this inventor.

  In the model generation step, it is desirable to generate a finite element model having a node in the gas flow path formed in the separator. According to this configuration, since the strain of the element of the polymer electrolyte membrane in contact with the groove can be calculated with high accuracy, it is possible to evaluate durability with higher accuracy.

  In the equivalent stress calculation step, it is desirable to calculate the equivalent stress using the Mises equivalent stress formula. According to this configuration, durability can be easily evaluated.

  The single-cell durability evaluation method determines whether or not the evaluation value derived in the evaluation value deriving step has converged. If it is determined that the evaluation value has converged, the evaluation value is output in the output step and converged. If it is determined that there is not, it is preferable to further include a convergence determining step of changing the number of nodes of the element of the single cell finite element model, generating the finite element model again, and deriving an evaluation value. According to this configuration, the number of nodes of the single-cell finite element model is an appropriate value, and the calculation for evaluation is performed. Therefore, it is possible to further evaluate durability.

  The single cell durability evaluation method determines whether or not the evaluation value derived in the evaluation value deriving step satisfies a preset end condition, and outputs the evaluation value when it is determined that the evaluation value is satisfied. A condition determination step of generating the finite element model again based on a parameter different from the parameter for deriving the evaluation value and deriving the evaluation value if it is determined that the evaluation value is not satisfied. Is desirable. According to this configuration, since the parameters of a single cell having a predetermined durability can be known, it can be used for the design of the single cell.

  By the way, the present invention can be described as an invention of a single cell durability evaluation method as described above, and can also be described as an invention of a single cell durability evaluation apparatus and a durability evaluation program as follows. . This is substantially the same invention only in different categories and the like, and has the same operations and effects.

  That is, the single-cell durability evaluation apparatus according to the present invention includes a polymer electrolyte membrane, two plate-like electrodes provided on both sides of the polymer electrolyte membrane, and a groove-like shape for supplying gas to the electrodes. A single cell durability evaluation apparatus for evaluating the durability of a single cell of a fuel cell including two plate-like separators in which gas flow paths are formed and a sealing material for sealing a side surface of an electrode. A receiving unit that receives input of parameters relating to the single cell, a model generating unit that generates a finite element model of a single cell divided into a plurality of elements based on the parameters received by the receiving unit, and a receiving unit Based on the boundary condition of the moisture distribution included in the accepted parameters, the moisture distribution of the polymer electrolyte membrane in the finite element model generated by the model generating means is calculated by the finite element method. Each element of the polymer electrolyte membrane is calculated from the moisture distribution calculating means, the moisture distribution calculated by the moisture distribution calculating means, and the water absorption linear expansion coefficient and elastic modulus of the polymer electrolyte membrane included in the parameters accepted by the accepting means. Strain / stress calculation means for calculating each strain and stress by the finite element method, and equivalent stress calculation means for calculating the equivalent stress in each element from the stress in each element calculated by the strain / stress calculation means And an evaluation value deriving means for deriving an evaluation value for evaluating the durability of the single cell from the equivalent stress in each element calculated by the equivalent stress calculating means, and an evaluation value derived by the evaluation value deriving means. Output means for outputting.

  Further, the information processing apparatus is provided with a polymer electrolyte membrane, two plate-like electrodes provided on both sides of the polymer electrolyte membrane, and a groove-like gas flow path for supplying gas to the electrodes 2 A single cell durability evaluation program for performing a process for evaluating the durability of a single cell of a fuel cell comprising two plate-like separators and a sealing material that seals the side surfaces of an electrode, and an information processing apparatus A reception process that receives input of parameters relating to a single cell, a model generation process that generates a finite element model of a single cell divided into a plurality of elements based on the parameters received by the reception process, and a reception process Based on the boundary condition of the moisture distribution included in the accepted parameters, the moisture distribution of the polymer electrolyte membrane in the finite element model generated by the model generation process is calculated using the finite element method. From the moisture distribution calculation process calculated by the calculation, the moisture distribution calculated by the moisture distribution calculation process, and the water absorption linear expansion coefficient and elastic modulus of the polymer electrolyte membrane included in the parameters received by the receiving process, the polymer electrolyte membrane The equivalent stress of each element is calculated from the strain / stress calculation process that calculates the strain and stress of each element of the above by the finite element method and the stress of each element calculated by the strain / stress calculation process. Derived by the stress calculation process, the evaluation value deriving process for deriving the evaluation value for evaluating the durability of the single cell from the equivalent stress in each element calculated by the equivalent stress calculating process, and the evaluation value deriving process And an output process for outputting an evaluation value.

A single cell of a fuel cell according to the present invention includes a polymer electrolyte membrane, two plate-like electrodes provided on both sides of the polymer electrolyte membrane, and a groove-like gas flow path for supplying gas to the electrodes. A single cell of a fuel cell including two formed plate-shaped separators and a sealing material for sealing the side surface of the electrode, and the durability of the single cell having a coefficient c of 1.2 The evaluation value according to the property evaluation method is characterized in that α is in the range of 0 [mm ² ] to 50.0 [mm ² ] and β is in the range of 0 to 0.01. Since the above single cell can remarkably suppress the mechanical deterioration due to water absorption stress, it can be a highly durable single cell.

  According to the present invention, the durability of a single cell of a fuel cell can be evaluated in consideration of a stress corresponding to the moisture distribution of the polymer electrolyte membrane, that is, a water absorption stress. Further, according to the present invention, the evaluation can be performed in the information processing apparatus, and it is not necessary to actually create and evaluate the single cell, so that the durability of the single cell can be easily evaluated. Furthermore, according to the present invention, a single cell of a fuel cell having high durability can be provided.

  Hereinafter, preferred embodiments of a single cell durability evaluation method, a durability evaluation system, and a durability evaluation program according to the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  First, a single cell to be evaluated by the durability evaluation method according to the present embodiment will be described. In addition, since the durability evaluation method according to the present embodiment is a method in an information processing apparatus, it is not necessary to actually use a single cell. FIG. 1 shows a configuration of a single cell 1 of a flat solid polymer fuel cell, which is an object of the evaluation method according to the present embodiment. As described above, the single cell 1 includes the polymer electrolyte membrane 10, the electrodes 11a and 11b, the conductive separators 12a and 12b, and the annular gas seal materials 13a and 13b.

  The polymer electrolyte membrane 10 has a polymer having an ion exchange group as a main component. Examples of such a polymer having an ion exchange group include a fluorocarbon polymer having a sulfonic acid group exemplified by Nafion (registered trademark, manufactured by DuPont), or a polymer obtained by introducing a sulfonic acid group into an aromatic polymer having excellent heat resistance. There is. Such a polymer usually has an ion exchange capacity of 0.2 to 4 meq / g.

  One of the electrodes 11a and 11b is a fuel electrode (anode), and the other is an air electrode (cathode). The electrodes 11a and 11b are usually configured such that a gas diffusion layer and a catalytic reaction layer are laminated. The catalytic reaction layer is formed in close contact with the main surface of the polymer electrolyte membrane 10. As the gas diffusion layer, porous carbon nonwoven fabric, carbon paper, or the like is used. The catalytic reaction layer is usually a layer mainly composed of a catalyst component such as platinum fine particles supported on particulate or fibrous carbon such as activated carbon or graphite and a polymer electrolyte.

  An assembly in which the polymer electrolyte membrane 10 and the pair of electrodes 11a and 11b sandwiching the polymer electrolyte membrane 10 are integrated in advance is generally called MEGA. The annular gas seal members 13a and 13b are arranged around the MEGA so that the fuel gas and the oxidant gas supplied after the battery assembly do not leak to the outside or the two kinds of gases are mixed with each other. Seal. The annular gas seal members 13a and 13b are usually made of a rubber elastic body, and silicon rubber, fluororesin rubber or the like is used.

  On both sides of the MEGA, conductive separators 12a and 12b are arranged for mechanically fixing the MEGA and electrically connecting adjacent MEGAs in series with each other. Groove-shaped gas passages for supplying fuel gas and oxidant gas to the electrode surface and carrying away generated gas and surplus gas are formed at portions of the conductive separators 12a and 12b that are in contact with the MEGA. The gas flow path can be provided as a separate part from the conductive separators 12a and 12b, but the conductive separators 12a and 12b can be cut or pressed according to the material of the conductive separators 12a and 12b. A method of providing a gas flow path by providing grooves and ribs on the surface of 12b is common. The separators 12a and 12b are provided with manifolds 14a and 14b for supplying and exhausting gas to grooves formed in the separators 12a and 12b, respectively. The separators 12a and 12b and the gas seal members 13a and 13b may be provided with through holes that can be fastened with bolts in order to sandwich the MEGA. The separators 12a and 12b are obtained by forming a conductive material such as a carbon material or a metal material.

  FIG. 2 shows surfaces of the separators 12a and 12b that are in contact with the electrodes 11a and 11b. 2A is a type in which the gas flow path 21 meanders, and FIG. 2B is a type in which the gas flow path 21 extends in parallel. In FIG. 2, the portion surrounded by the outer peripheral edge 22 of the gas flow path 21 is in contact with the electrodes 11a and 11b, and fuel gas or oxidant gas is provided in this portion. Further, a groove 23 is provided from the manifold 14 in a portion of the gas flow path 21 surrounded by the outer peripheral edge 22 in order to provide gas.

  In the present invention, in the polymer electrolyte membrane 10 in which water absorption stress mainly occurs among the constituent elements of the unit cell 1 of the planar fuel cell, an effective power generation region related to an electric reaction and an ineffective power generation region other than the effective power generation region. And set. FIG. 3 shows the main surface of the polymer electrolyte membrane 10. In the polymer electrolyte membrane 10, a portion surrounded by the outer peripheral edge 24 is a region in contact with the electrode 11. This area is defined as an effective power generation area. In the polymer electrolyte membrane 10, the portion outside the portion surrounded by the outer peripheral edge 24 is a region not in contact with the electrode 11, and this region is set as an ineffective power generation region. In a normal planar fuel cell, the area where the two electrodes 11a and 11b are in contact with each other on the surface of the polymer electrolyte membrane 10 is the same area. However, when the region is not the same, the region where the air electrode contacts is preferentially used. The portion surrounded by the outer peripheral edge 25 inside the effective power generation region is a region obtained by projecting the portion surrounded by the gas flow path 21 described above.

  Subsequently, the durability evaluation apparatus for the single cell 1 according to the present embodiment will be described. FIG. 4 shows a durability evaluation apparatus 30 for the single cell 1 according to this embodiment. The durability evaluation of the single cell 1 is performed by executing the durability evaluation method for the single cell 1 in the durability evaluation apparatus 30. Specifically, the information processing apparatus as the durability evaluation apparatus 30 corresponds to a workstation, a personal computer (PC), or the like. The durability evaluation device 30 is configured by hardware such as a CPU (Central Processing Unit) and a memory, for example, and functions as the durability evaluation device 30 described later when these components are operated by a program or the like. Is done.

  In the present invention, it is necessary to generate a finite element model of the single cell 1 and perform a calculation by the finite element method. In the present embodiment, these can use existing methods and programs. For example, SDRC / FEMAP, which is general-purpose finite element creation software, can be used to generate a finite element model. Further, NE / Nastran Version 7.0 (manufactured by Noran Engineering Inc.), which is a finite element method program, can be used for the calculation by the finite element method.

  As shown in FIG. 4, the durability evaluation apparatus 30 for the single cell 1 includes a reception unit 31, a model generation unit 32, a moisture distribution calculation unit 33, a strain / stress calculation unit 34, and an equivalent stress calculation unit 35. The evaluation value deriving unit 36, the output unit 37, and the determining unit 38 are provided. The durability evaluation device 30 is connected to the input device 40, and information is input from the input device 40.

  The accepting unit 31 is accepting means for accepting input of parameters relating to the single cell 1. The parameter is input from the input device 40. However, the parameter need not be input from an external device, and information stored in advance by the durability evaluation device 30 may be input. The parameters relating to the single cell 1 include information on the size and shape of the members constituting the single cell 1, information on the material of the member such as the water absorption linear expansion coefficient and the elastic modulus of the polymer electrolyte membrane 10, and the binding of each member ( Includes load to be screwed. The parameter includes a boundary condition for moisture distribution. The boundary condition is, for example, that the water concentration with respect to the water absorption rate is 0.0 at the end of the polymer electrolyte membrane 10 and 1.0 at the portion where the gas flow path 21 of the polymer electrolyte membrane 10 is projected. Here, the water absorption rate indicates a saturated water absorption state, that is, a state in which the polymer electrolyte membrane 10 is impregnated with water and absorbed. The parameters include information necessary for generating the finite element model of the single cell 1, for example, information on the number of nodes and the length of the element side. Each parameter received by the receiving unit 31 is sent to the model generating unit 32 and the like and used as necessary.

  The model generation unit 32 is a model generation unit that generates a finite element model of the single cell 1 divided into a plurality of elements based on the parameters received by the reception unit 31. The generation of the model may be performed by an existing method as described above.

  This finite element model desirably has a node in the gas flow path 21 formed in the separators 12a and 12b. Since the gas flow path 21 is a gap, a pressure difference is generated between the gas flow path 21 and other portions, and a force as if embossed is applied to the electrodes 11a and 11b. Accordingly, in the finite element model, as shown in FIG. 5A, if one side of the element including the gas flow path 21 is large and the flow path portion does not have the node 26, the effect of distortion in the flow path portion is expressed in the model. It is impossible to calculate stress with high accuracy.

  Therefore, for example, as shown in FIG. 5B, it is preferable that one side of the element is at least 1/2 of the width of the flow path, and a node 26 is provided in the gas flow path 21 portion. Further, as shown in FIG. 5C, the intermediate node 26 may be provided in the portion of the gas flow path 21 although one side of the element is large. However, when the gas flow path 21 is sufficiently fine and has no great influence, the node 26 does not necessarily have to be provided in the gas flow path 21 portion.

  For the nodes and elements of the finite element model, for example, the portion of the polymer electrolyte membrane 10 may be divided, and the portions of the electrodes 11a and 11b that are in contact with the gas flow path 21 may be set under the above conditions. The generated finite element model is used for calculation by the following constituent elements.

  The moisture distribution calculating unit 33 calculates the moisture distribution in the finite element model generated by the model generating unit 32 based on the boundary condition of the moisture distribution included in the parameter received by the receiving unit 31 by the finite element method. It is a distribution calculation means. The calculation will be described in detail later. The calculated moisture distribution information is transmitted to the strain / stress calculator 34.

  The strain / stress calculator 34 calculates the polymer from the moisture distribution calculated by the moisture distribution calculator 33 and the water absorption linear expansion coefficient and elastic modulus of the polymer electrolyte membrane 10 included in the parameters received by the receiver 31. It is a strain / stress calculation means for calculating the strain and stress of each element of the electrolyte membrane 10 by the finite element method. The calculation will be described in detail later. The calculated stress of each element is transmitted to the equivalent stress calculation unit 35.

  The equivalent stress calculation unit 35 is equivalent stress calculation means for calculating the equivalent stress in each element from the stress in each element calculated by the strain / stress calculation unit 34. The equivalent stress refers to a scalar amount having no directionality calculated from a stress that is a tensor amount. The calculation of the equivalent stress is intended to facilitate the calculation for deriving the evaluation value using the stress value in the subsequent stage, since the stress calculated by the strain / stress calculation unit 34 is usually a tensor amount. It is. The calculated equivalent stress of each element is transmitted to the evaluation value deriving unit 36.

  The evaluation value deriving unit 36 is an evaluation value deriving unit that derives an evaluation value for evaluating the durability of the single cell 1 from the equivalent stress in each element calculated by the equivalent stress calculation unit 35. The evaluation value is derived from a value indicating a range in which a certain level or more of stress is generated in the ineffective power generation region of the polymer electrolyte membrane 10 by a preset calculation formula. More specifically, the evaluation value and its derivation will be described later. The derived evaluation value is transmitted to the output unit 37 or the determination unit 38.

  The output unit 37 is an output unit that outputs the evaluation value derived by the evaluation value deriving unit 36. For example, the output is performed on a display device (not shown) included in the durability evaluation device 30. With this output, the endurance evaluation result of the single cell 1 is referred to by the user. Further, in order to show the evaluation result in a more easily understandable manner, a stress graph or the like may be output together with the evaluation value. The output is not necessarily performed on the display device, and may be performed on another device.

  The determination unit 38 is means for determining whether or not to repeat a series of processes for evaluating durability of the single cell 1. Specifically, the determination unit 38 determines whether or not the evaluation value derived by the evaluation value deriving unit 36 has converged. If it is determined that the evaluation value has not converged, the number of nodes of the elements of the finite element model is changed. Then, it is a convergence determination unit that causes the model generation unit 32 to generate a finite element model again and derive an evaluation value. The determination unit 38 causes the output unit 37 to output the evaluation value when determining that the convergence has occurred.

  Further, the determination unit 38 determines whether or not the evaluation value derived by the evaluation value deriving unit 36 satisfies a preset termination condition. If it is determined that the evaluation value is not satisfied, the determination unit 38 relates to the evaluation value derivation. This is condition determination means for causing the model generation unit 32 to generate a finite element model again based on a parameter different from the parameter and derive an evaluation value. If it is determined that the determination unit 38 is satisfied, the determination unit 38 causes the output unit 37 to output the evaluation value. The processing of the determination unit 38 will be described in detail later.

  The input device 40 is a device for inputting information to the durability evaluation device 30 used by the user. Specifically, a device such as a keyboard is equivalent.

  Subsequently, the durability evaluation method of the single cell 1 according to the present embodiment (processing executed in the durability evaluation apparatus 30) will be described using the flowcharts of FIGS. First, the basic process of the durability evaluation method will be described as the process of the first embodiment. Subsequently, more practical processes will be described with reference to FIGS. 7 and 8 according to the second and third embodiments. This will be described as processing.

[First Embodiment]
In the durability evaluation method, first, the user uses the input device 40 to input parameters related to the evaluation target single cell 1 to the durability evaluation device 30. Here, the parameter may be directly input by the user, or the parameter may be stored in advance in the durability evaluation apparatus 30 and specified by the user. When the input is made, in the durability evaluation device 30, the parameter is received by the receiving unit 31 (S01, receiving step). The parameter whose input has been accepted is transmitted to the model generation unit 32.

  Subsequently, the model generation unit 32 generates a finite element model of the single cell 1 divided into a plurality of elements based on the parameters. The generation of the finite element model is performed as follows. First, the structure of the single cell 1 is set based on the information on the size and shape of the members constituting the single cell 1 (S02, model generation step). Subsequently, the set structure of the unit cell 1 is divided into elements based on the information on the number of nodes and the lengths of the sides of the elements (S03, model generation step). In setting the finite element model, an effective power generation region and an ineffective power generation region are set in the polymer electrolyte membrane 10. In the subsequent processing, calculation is performed using the finite element model generated in this way.

  Subsequently, the moisture distribution calculation unit 33 calculates the moisture distribution in the generated finite element model based on the boundary condition of the moisture distribution included in the parameter (S04, moisture distribution calculation step). Specifically, the calculation of the moisture distribution can be performed as follows. It is assumed that the effective power generation region of the polymer electrolyte membrane 10 in the finite element model is in a saturated water absorption state, and the outer edge portion of the polymer electrolyte membrane 10 is in an absolutely dry state. Subsequently, the moisture distribution in the ineffective power generation region is solved using Fick's second law, which is a diffusion equation when there is no external force. The calculation of the moisture distribution is performed in all modeled regions (including separators). Therefore, this calculation is performed for the entire system. When solving using Fick's second law, the diffusion coefficient of water is used. The above contents are described in detail in “Iwanami Physical and Chemical Dictionary, 5th edition, page 1149, Iwanami Shoten, 1998”. Specifically, the moisture distribution obtained by this calculation is, for example, information on the amount of moisture contained in each element (water content). Information indicating the calculated moisture distribution is transmitted to the strain / stress calculator 34.

  Subsequently, the strain of each element of the polymer electrolyte membrane 10 is calculated from the moisture distribution calculated by the strain / stress calculator 34 and the water absorption linear expansion coefficient and elastic modulus of the polymer electrolyte membrane 10 included in the parameters. And the stress are calculated (S05, strain / stress calculation step). Here, the water absorption linear expansion coefficient may be assumed to be equal in the direction along the main surface of the polymer electrolyte membrane 10 and in the thickness direction. The water absorption linear expansion coefficient (in the direction along the main surface of the polymer electrolyte membrane 10) input in the input step is preferably obtained in advance by the following experimental method. The length Ld of one side of the polymer electrolyte membrane 10 is measured after the polymer electrolyte membrane 10 is immersed in hot water at 80 ° C. for about 1 hour to swell and absorb water. The length Lw of one side when the water adsorption reaches equilibrium at 23 ° C. and 50% relative humidity is measured. From these values, 100 × (Lw−Ld) / Ld is obtained, and this is taken as the water absorption linear expansion coefficient. The calculated strain information of each element is transmitted to the equivalent stress calculation unit 35.

  Note that the elastic modulus used for the stress calculation is preferably obtained in advance by an experimental method by performing a tensile test or the like after water absorption and swelling of the polymer electrolyte membrane. At this time, the moisture content of the polymer electrolyte membrane 10 subjected to the tensile test is obtained by an absolute dry weight meter.

９成分それぞれを評価するよりも、スカラー量である応力τを用いて評価した方が、簡便かつ確実である。計算された各要素の相当応力の情報は、評価値導出部３６に送信される。 Subsequently, the equivalent stress calculator 35 calculates the equivalent stress in each element of the polymer electrolyte membrane 10 from the calculated stress of each element (S06, stress calculation step). Here, the equivalent stress is preferably calculated using the Mises equivalent stress formula. Since stress is originally a tensor amount, it consists of nine components as follows, and is usually obtained as these component values by the finite element method. The x direction and the y direction orthogonal to each other are set along the main surface of the polymer electrolyte membrane 10, and the z direction is set to be orthogonal to the x direction and the y direction in the thickness direction. For each element, the stress components σ _x , σ _y , σ _z and τ _xy , τ _yz , τ _zx in the x direction, the y direction, and the z direction are obtained by calculation using the finite element method. In the present embodiment, the equivalent stress τ, which is a scalar amount, is obtained using the Mises equivalent stress equation represented by the following (Equation 3), and the equivalent stress is set as the equivalent stress in each element.

Rather than evaluating each of the nine components, it is simpler and more reliable to evaluate using the stress τ, which is a scalar quantity. Information on the calculated equivalent stress of each element is transmitted to the evaluation value deriving unit 36.

Subsequently, the evaluation value deriving unit 36 derives an evaluation value for evaluating the durability of the single cell 1 from the calculated equivalent stress in each element. Specifically, the evaluation value is derived as follows. First, an average value S _av of stresses of elements in the effective power generation area among the elements whose stresses are calculated is calculated. Subsequently, an element of the ineffective power generation region that is equal to or greater than c × S _av is extracted for the coefficient c (S07, evaluation value deriving step). Here, the coefficient c is a predetermined value of 1 or more. Specifically, the coefficient c is desirably set to 1.2. This specific numerical value is a value empirically obtained by the inventor of the present application, and enables more appropriate durability evaluation.

導出された評価値であるα及びβは出力部３７に送信される。 Subsequently, the total volume V _{z of} the extracted elements of the ineffective power generation area is obtained. The volume V0 of the polymer electrolyte membrane, the value of the thickness d of the volume V _y and the polymer electrolyte membrane of the effective power generation region of the polymer electrolyte membrane 10 is determined from parameters such as the unit cell. From these values, α and β are derived as evaluation values by the following (Expression 1) and (Expression 2) (S08, evaluation value deriving step).

The derived evaluation values α and β are transmitted to the output unit 37.

  Subsequently, α and β are output as durability evaluation values of the single cell 1 by the output unit 37 (S09, output step).

In addition, in the evaluation value represented by α and β, the inventor of the present application has α in the range of 0 [mm ² ] or more and 50.0 [mm ² ] or less, and β is 0 or more and 0.01 or less. It has been found that a single cell in the range of can be a highly durable single cell because it is possible to remarkably suppress mechanical deterioration due to water absorption stress. In addition, in order to make α and β within the above ranges, in addition to the water absorption linear expansion coefficient and elastic modulus of the polymer electrolyte membrane, control of the contact area (effective power generation region) of the polymer electrolyte membrane and the catalyst layer, the gas of the separator It can be controlled by changing the shape of the flow path, and according to the evaluation method of the present invention, it is easy to use such parameters as input information without actually assembling a single cell and conducting a durability evaluation test. A single cell having high durability can be designed. In addition, both α and β are preferably smaller values because they are excellent in durability, and in particular, α is more preferably 40.0 [mm ² ] or less, and further preferably 30.0 [mm ² ] or less. 20.0 [mm ² ] or less is particularly preferable. Further, β is more preferably 0.008 or less, and further preferably 0.006 or less.

  The evaluation value deriving unit 36 derives not only the durability evaluation value of the single cell 1 but also the evaluation value of the power generation function of the single cell 1 and combines it with the durability evaluation value in the output by the output unit 37. May be output. For example, the evaluation value of the power generation function is calculated by the effective power generation area ratio = (area of the effective power generation area) / (area of the main surface of the separator). It is evaluated that the power generation performance of the single cell 1 is higher as the evaluation value is higher.

  In addition, since the polymer electrolyte membrane 10 has a significantly smaller dimension in the thickness direction than the dimension in the plane direction, the calculation can be simplified by not dividing the element in the thickness direction during element division (S03). That is, for the polymer electrolyte membrane 10, the calculation can be simplified by dividing the three-dimensional element division into the two-dimensional element division.

  As described above, according to the present embodiment, the durability of the single cell 1 of the fuel cell can be evaluated in consideration of the stress corresponding to the moisture distribution of the polymer electrolyte membrane 10, that is, the water absorption stress. In addition, according to the present embodiment, evaluation can be performed in the durability evaluation apparatus 30 that is an information processing apparatus, and it is not necessary to actually create and evaluate the single cell 1. Durability can be evaluated.

  Further, if α and β are used as in the present embodiment, the durability of the single cell 1 can be appropriately evaluated in the above evaluation method. However, in the evaluation of durability, it is not always necessary to use α and β as evaluation values.

[Second Embodiment]
The process of this embodiment is a process in which a process for increasing the reliability of the evaluation value is added. FIG. 7 shows a flowchart of processing of the present embodiment. The value of the evaluation value derived using the calculation of the finite element method can change according to the number of nodes in the element division (S03). In the present embodiment, even if a certain number of nodes is exceeded, a value that does not substantially change the evaluation value, that is, a convergence value of the evaluation value is obtained.

  As shown in FIG. 7, the process from the parameter input reception (S01) to the evaluation value derivation (S08) is the same as the process of the first embodiment. When the evaluation value is derived, the evaluation value is transmitted to the determination unit 38. The determination unit 38 determines whether or not the evaluation value has converged (S10, convergence determination step). Specifically, the derived evaluation value is compared with the evaluation value derived in the previous iteration, and if the difference is within a predetermined threshold, it is determined that the convergence has occurred.

  If the determination unit 38 determines that the evaluation value has converged, the evaluation value is transmitted to the output unit 37 and output by the output unit 37 (S09, output step). If it is determined that the convergence has not occurred, the determination unit 38 causes the model generation unit 32 to increase the number of nodes of the finite element model of the single cell 1 (S11, convergence determination step), and again Control is performed so as to perform division (S03, model generation step). The number of nodes is increased, for example, so that the interval between one side of the element is halved. After the element generation is performed by the model generation unit 32, a series of processes (S04 to S08) for deriving the evaluation value is performed again.

  Information such as the threshold value used in the above processing and how to increase the number of nodes may be included in the parameters received by the receiving unit 31 or stored in advance by the durability evaluation device 30. It's okay. As described above, according to the present embodiment, the reliability of the evaluation value can be increased.

[Third Embodiment]
The processing of this embodiment is processing for knowing the parameters of the single cell 1 having a predetermined durability. FIG. 8 shows a flowchart of the processing of this embodiment.

As shown in FIG. 7, the process from the parameter input reception (S01) to the evaluation value convergence determination (S10, S11) is the same as the process of the second embodiment. When the above process ends, the determination unit 38 determines whether or not the evaluation value satisfies a preset end condition (S12, condition determination step). Specifically, the preset end condition is, for example, whether or not an evaluation value is below a set threshold. The threshold is preferably set to 50.0 [mm ² ] for α and 0.01 for β, for example, considering the operating life of the fuel cell. This value is obtained empirically by the inventor of the present application.

  If the determination unit 38 determines that the end condition is satisfied, the evaluation value is transmitted to the output unit 37 and output by the output unit 37 (S09, output step). When it is determined that the end condition is not satisfied, the determination unit 38 causes the model generation unit 32 to change the parameter value (S12, convergence determination step), and configures the configuration of the finite element model of the single cell 1. Control is performed so as to be set again (S02, model generation step). This change is preferably performed so as to reduce the evaluation value.

  The parameter value to be changed is, for example, a constant that determines the type of material, such as an elastic modulus and a water absorption coefficient of linear expansion. The parameter is changed by setting and changing an upper limit value, a lower limit value, and a step size, respectively. Other than that, the parameter can be changed by changing the shape of the gas flow path 21, reducing the amount of ion exchange groups introduced into the polymer electrolyte related to proton conduction of the polymer electrolyte membrane 10, or the polymer electrolyte membrane 10. May be one corresponding to those crosslinked by electron beam crosslinking, thermal crosslinking, peroxide crosslinking, or the like. Moreover, you may change the magnitude | size of the member which comprises the single cell 1, and a shape. After the finite element model is set by the model generation unit 32, a series of processes (S03 to S08, S10, S11) for deriving the evaluation value is performed again.

  Note that the threshold value used in the above process, information on how to change parameters, and the like may be included in the parameters accepted by the accepting unit 31, or stored in advance by the durability evaluation device 30. Good.

  Further, in the above-described processing, it is preferable to perform the above-described evaluation value of the power generation function while maintaining the ratio of the effective power generation area = (the area of the effective power generation area) / (the area of the main surface of the separator) at a predetermined value or more. That is, it is preferable to set a parameter such that the effective power generation area ratio is a predetermined value or more. According to the present embodiment, a parameter having a predetermined durability can be known, which can be used for designing the single cell 1. Further, if the evaluation value of the power generation function is also taken into consideration, the single cell 1 that practically balances the operating life of the fuel cell and the power generation efficiency can be easily designed.

  Subsequently, a durability evaluation program for the single cell 1 for causing the information processing apparatus to execute the above-described processing for evaluating the durability of the single cell 1 will be described. As shown in FIG. 8, the durability evaluation program 51 of the single cell 1 is stored in a program storage area 50a formed in a recording medium 50 provided in the information processing apparatus.

  The durability evaluation program 51 of the single cell 1 includes a main module 51a that centrally controls the durability evaluation processing of the single cell 1, a reception module 51b, a model generation module 51c, a moisture distribution calculation module 51d, A stress calculation module 51e, an equivalent stress calculation module 51f, an evaluation value derivation module 51g, and an output module 51h are configured. The functions realized by executing each of the above are the same as the functions of the units 31 to 37 corresponding to the modules 51b to 51h provided in the durability evaluation apparatus 30 of the single cell 1.

  The durability evaluation program 51 of the single cell 1 may be configured so that part or all of the durability evaluation program 51 is transmitted via a transmission medium such as a communication line and received and recorded (including installation) by another device. Good.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples.

[Example 1 in durability evaluation method, Example 1 in single cell]
In this example, the single cell 1 is actually created and the durability is measured and compared with the evaluation by the durability evaluation method according to the present invention. The single cell 1 was produced as follows.

Synthesis Example 1 (Synthesis of polymer electrolyte)
(A) Synthesis of Polyethersulfone 1000 g of a polyethersulfone having a hydroxyl group (Sumika Excel PES4003P manufactured by Sumitomo Chemical Co., Ltd.) in a nitrogen atmosphere was dissolved in 2500 ml of N, N-dimethylacetamide (hereinafter referred to as DMAc). Further, 11.0 g of potassium carbonate, 53.6 g of decafluorobiphenyl, and 50 ml of toluene were added and reacted at 80 ° C. for 2 hours and at 100 ° C. for 1 hour. Thereafter, the reaction solution was added to methanol to precipitate a polymer, followed by filtration and drying to obtain polyethersulfones (d). This d is a polyethersulfone having a terminal substituted with a nonafluorobiphenyloxy group.

(B) Synthesis of poly (2,6-diphenylphenylene ether) 2.94 g (30.0 mmol) of anhydrous cuprous chloride and 3.51 g (30.0 mmol) of N, N, N ′, N′-tetramethylethylenediamine Were stirred in 1500 ml of chlorobenzene at 40 ° C. for 60 minutes in the atmosphere. To this, 17.1 g (60.0 mmol) of 2,2 ′, 6,6′-tetramethylbisphenol A and 148 g (600 mmol) of 2,6-diphenylphenol were added and stirred at 40 ° C. for 7 hours in the atmosphere. After the completion of the reaction, the polymer was precipitated by pouring into methanol containing hydrochloric acid, filtered and dried to obtain poly (2,6-diphenylphenylene ether) (PE3) having hydroxyl groups at both ends.

(C) Synthesis of block copolymer To a flask equipped with an azeotropic distillation apparatus, 160 g of PE3, 32 g of potassium carbonate, 3500 ml of DMAc, and 200 ml of toluene were added, and after stirring and dehydrating under azeotropic conditions of toluene and water Toluene was distilled off. 640g of said d was added here, and it heat-stirred at 80 degreeC for 5 hours, 100 degreeC for 5 hours, and 120 degreeC for 3 hours. The reaction solution was added dropwise to a large amount of hydrochloric acid methanol, and the resulting precipitate was collected by filtration and dried under reduced pressure at 80 ° C. to obtain a block copolymer. After stirring 600 g of the obtained block copolymer together with 6000 ml of 98% sulfuric acid at room temperature to obtain a uniform solution, stirring was further continued for 24 hours. The obtained solution was dropped into a large amount of ice water, and the resulting precipitate was collected by filtration. Further, the mixer washing with ion-exchanged water was repeated until the washing solution became neutral, and then dried at 40 ° C. under reduced pressure to obtain a sulfonated block copolymer.

Synthesis Example 2 (Synthesis of additives)
A polymer electrolyte in which phosphonic acid was introduced into an aromatic polymer was synthesized by the method described in Examples of JP-A-2003-238678, and used as an additive.

Preparation of electrode 500 mg of platinum-supporting carbon carrying 30 wt% of platinum was added to 5 ml of Nafion solution (5 wt%, manufactured by Aldrich), and stirred well to prepare a catalyst layer solution. This catalyst layer solution was applied on a carbon cloth (manufactured by E-TEK) by screen printing so that the platinum carrying density was 0.6 mg / cm ² , the solvent was removed, and the gas diffusion layer-catalyst reaction layer A joined body was obtained.

Formation of Polymer Electrolyte Membrane The block copolymer obtained in Synthesis Example 1 and the additive obtained in Synthesis Example 2 were mixed at a mass ratio of 95: 5, and further mixed with N-methylpyrrolidone. It melt | dissolved so that it might become a density | concentration of solid content 27 weight%, and obtained the polymer electrolyte solution. The polymer electrolyte solution was dropped onto a polyethylene porous membrane fixed in a glass plate shape. The polymer electrolyte solution was uniformly spread on the porous membrane using a wire coater, the coating thickness was controlled using a bar coater having a clearance of 0.3 mm, and dried at 80 ° C. under normal pressure. Thereafter, it was immersed in 1 mol / l hydrochloric acid and further washed with ion exchange water to obtain a polyethylene composite polymer electrolyte membrane (polymer electrolyte membrane 10).

  The obtained polymer electrolyte membrane 10 was immersed in warm water at 80 ° C. for 1 hour to swell and absorb water, and the length of one side of the water-absorbing saturated membrane was Ld1, and water was adsorbed at 23 ° C. and 50% relative humidity. When it reached parallel, the length Lw1 of the one side was measured, and the water absorption linear expansion coefficient in the plane direction was determined from the formula 100 × (Lw1−Ld1) / Ld1, and it was 6.0%.

Further, the polymer electrolyte membrane 10 was saturated with water in the same manner as described above, and was subjected to a tensile test based on JIS K7127 (measurement temperature 80 ° C., relative humidity 50%, measuring instrument: environmentally controlled tensile testing machine manufactured by Instron). The elastic modulus was determined to be 28.94 MPa. Furthermore, K.K. D. Kreuer, Journal of Membrane Science, 185, p29-39, (2001), the diffusion coefficient of the sulfonated polyetherketone membrane and the diffusion coefficient of the polymer electrolyte membrane used in this example are almost equivalent. The diffusion coefficient was 1.0 × 10 ⁻⁹ / mm ² · sec. These values are used as input parameters in the durability evaluation method for the single cell 1 according to the present invention.

9 is a cross-sectional view of the single cell 1 used in this example. A commercially available JARI cell (sales: Eiwa Co., Ltd., hereinafter referred to as cell 1) was used. Here, in the cell 1, the separator 12 has a meandering gas flow path 21 (flow path groove 1 mm) having a size of a surface in contact with the MEGA of 80 mm × 80 mm (L1 in FIG. 10 is 80 mm). The area formed by the outer edge of the gas flow path 21 is 52 mm × 52 mm (L2 in FIG. 10 is 52 mm). The gas seal material 13 is a laminate of silicone rubber-polyethylene naphthalate-silicone rubber (thickness 230 μm, 8.0 cm × 8.0 cm), and a central 58 mm × 58 mm (L3 in FIG. 10 is 58 mm) region is cut out. ing. The cell 1 is cut into 70 mm × 70 mm (L4 in FIG. 10 is 70 mm), and the gas diffusion layer-catalyst reaction layer joint cut out in the same shape as the perforated portion of the gas seal material 13. A single cell 1 by incorporating a body electrode 11 (the diffusion coefficient obtained by the same method as that of the polymer electrolyte membrane 10 described above was 1.0 × 10 ⁻⁷ / mm ² · sec) (that is, The size of the effective power generation area was set to 58 mm × 58 mm).

Durability Test Durability test was performed on the single cell 1 created as described above. Specifically, continuous fuel cell power generation was performed in which a constant current was continuously generated. The test conditions are as follows. Cell temperature: 95 ° C. Hubler temperature: 95 ° C. (anode), 95 ° C. (cathode). Gas flow rate: 70 ml / min (anode), 160 ml / min (cathode). Back pressure: 0.1 MPaG (anode), 0.1 MPaG (cathode). Current: 2.5A. As a result of the durability test, the voltage remained at a substantially constant value (0.8 V) from the start of the test to 1000 hours, and no decrease was observed. Further, no mechanical deterioration has occurred.

Evaluation according to the present invention The single cell 1 was evaluated by the durability evaluation method for the single cell 1 according to the present invention. α was 17.4 [mm ² ], β was 0.0036, and the effective power generation area ratio was 0.53. If α is 50.0 [mm ² ] or less and β is 0.01 or less, it can be determined that the battery has sufficient durability. Therefore, according to the durability evaluation method of the single cell 1 according to the present invention. Durability can be evaluated appropriately. In addition, since the effective power generation area ratio is approximately 0.3 or more, it can be determined that the single cell 1 has a sufficient power generation function even in this method. It was evaluated. FIG. 11 shows a graph of the stress of the polymer electrolyte membrane 10 calculated by the durability evaluation method for the single cell 1 according to the present invention. In the graph of FIG. 11, the horizontal axis represents the distance from the center of the polymer electrolyte membrane 10, and the vertical axis represents the normalized stress (the average stress in the effective power generation region is 1). In the ineffective power generation region, locations 1.2 times the stress of the average stress of the effective power generation region is occurring is in a size corresponding to the sum V _z of the volume element of the non-effective power generation area of the .

[Example 2 in durability evaluation method, Comparative example 1 in single cell]
The JARI cell 2 (sales: Eiwa Co., Ltd., hereinafter cell 2) equivalent to that of Example 1 except that the effective power generation area of the cell 1 used in Example 1 was changed to 52 mm × 52 mm (L3 in FIG. 10 was 52 mm). Used). The same polymer electrolyte membrane 10 and separator 12 as in Example 1 were used. The gas seal material 13 is a laminate of silicone rubber-polyethylene naphthalate-silicone rubber (thickness 230 μm, 80 mm × 80 mm), and a central 52 mm × 52 mm (L3 in FIG. 10 is 52 mm) region is cut out. The solid polymer electrolyte membrane 10 cut into 70 mm × 70 mm (L4 in FIG. 10 is cut into the cell 1) and the gas diffusion layer-catalyst reaction layer joint cut into the same shape as the opening of the gas seal material 13. The electrode 11 as a body was incorporated into the single cell 1 (that is, the size of the effective power generation area was set to 52 mm × 52 mm). As a result of the endurance test, the voltage remained at a constant value (0.78V) from the start of the test to about 120 hours, but after about 120 hours, a gas leak occurred and it was impossible to generate power continuously. Became.

The single cell 1 was evaluated by the durability evaluation method for the single cell 1 according to the present invention. α was 60.8 [mm ² ], β was 0.012, and the effective power generation area ratio was 0.42. Since α can be determined to have sufficient durability if it is 50.0 [mm ² ] or less and β is 0.01 or less, this example has sufficient durability. I can't say. The experimental results also appropriately show that the durability is low compared to Example 1 in the single cell. In addition, since the effective power generation area ratio is approximately 0.3 or more, it can be determined that the single cell 1 has a sufficient power generation function even in this method. It was evaluated. FIG. 11 shows a graph of the stress of the polymer electrolyte membrane 10 calculated by the durability evaluation method for the single cell 1 according to the present invention. In the ineffective power generation region, locations 1.2 times the stress of the average stress of the effective power generation region is occurring is in a size corresponding to the sum V _z of the volume element of the non-effective power generation area of the .

[Comparative Examples 1 and 2 in the durability evaluation method]
In the durability evaluation method of the single cell 1 according to the present invention in Example 1 and Example 2 in the durability evaluation method, the moisture distribution is calculated based on the boundary condition of the moisture distribution, and the durability is determined based on the moisture distribution. Sexuality was evaluated. The results when the moisture distribution is not properly considered are shown as Comparative Examples 1 and 2 in the durability evaluation method (corresponding to Examples 1 and 2 in the durability evaluation method, respectively). In this comparative example, the evaluation value was derived on the assumption that the moisture distribution is in a saturated water absorption state in the entire polymer electrolyte membrane. A graph of equivalent stress of the polymer electrolyte membrane 10 in Comparative Examples 1 and 2 is shown in FIG. From this graph, it was found that there was no correlation with the result of the corresponding durability test except that the position of the ineffective power generation region was different. Further, in the non-effective power generation region, the portion where 1.2 times the average stress in the effective power generation region is generated is larger than those in Examples 1 and 2. Furthermore, when the evaluation value was derived in Comparative Examples 1 and 2, in Comparative Example 1, α was 131 [mm ² ], β was 0.027, and in Comparative Example 2, α was 308 [mm ² ]. And β was 0.063. These results show that the difference in durability due to the single cell structure is evaluated lower than the evaluation results in the corresponding Examples 1 and 2, and thus the moisture distribution is not calculated as in the present invention. It was found that when the evaluation was performed, proper evaluation could not be performed.

[Example 3 in durability evaluation method, Comparative example 2 in single cell]
A cell manufactured by ElectroChem (hereinafter referred to as cell 3) generally used for a fuel cell was evaluated by the durability evaluation method of the single cell 1 according to the present invention. The separator 12 has a surface in contact with the MEGA having a size of 95 mm × 95 mm (L1 in FIG. 10 is 95 mm) and has a meandering gas flow path 21 (flow path width of 1 mm). The area formed was 51 mm × 51 mm (L2 in FIG. 10 was 51 mm). The effective power generation area is 51 mm × 51 mm (L3 in FIG. 10 is 51 mm), the size of the solid polymer electrolyte membrane 10 is 87 mm × 87 mm (L4 in FIG. 10 is 87 mm), and the water absorption linear expansion coefficient of the polymer electrolyte membrane 10 is The boundary conditions of the moisture distribution were the same as in Example 1. α was 272 [mm ² ], β was 0.036, and the effective power generation area ratio was 0.29. According to the durability evaluation method of the single cell 1 according to the present invention, the single cell 1 is insufficient in both durability and power generation function. FIG. 12 shows a graph of the stress of the polymer electrolyte membrane 10 calculated by the durability evaluation method for the single cell 1 according to the present invention. In the ineffective power generation region, locations 1.2 times the stress of the average stress of the effective power generation region is occurring is in a size corresponding to the sum V _z of the volume element of the non-effective power generation area of the .

[Example 4 in durability evaluation method, Comparative example 3 in single cell]
Another ElectroChem cell (hereinafter referred to as “cell 4”) generally used for a fuel cell was evaluated by the durability evaluation method of the single cell 1 according to the present invention. The separator 12 has a surface in contact with the MEGA having a size of 95 mm × 95 mm (L1 in FIG. 10 is 95 mm) and has a meandering gas flow path 21 (flow path width of 1 mm). The area formed was 22 mm × 22 mm (L2 in FIG. 10 was 22 mm). The effective power generation area is 22 mm × 22 mm (L3 in FIG. 10 is 22 mm), the size of the solid polymer electrolyte membrane 10 is 87 mm × 87 mm (L4 in FIG. 10 is 87 mm), and the water absorption linear expansion coefficient of the polymer electrolyte membrane 10 is The boundary conditions of the moisture distribution were the same as in Example 1. α was 662 [mm ² ], β was 0.087, and the effective power generation area ratio was 0.054. According to the durability evaluation method of the single cell 1 according to the present invention, the single cell 1 is insufficient in both durability and power generation function. FIG. 12 shows a graph of the stress of the polymer electrolyte membrane 10 calculated by the durability evaluation method for the single cell 1 according to the present invention. In the ineffective power generation region, locations 1.2 times the stress of the average stress of the effective power generation region is occurring is in a size corresponding to the sum V _z of the volume element of the non-effective power generation area of the .

The evaluation results of Example 1 and Comparative Examples 1 to 3 in the single cell are shown in the following table.

It is a structure schematic diagram of the single cell of the flat type solid polymer fuel cell which is the evaluation object of the durability evaluation method of the single cell concerning the embodiment of the present invention. It is the figure which showed the surface which contact | connects the electrode of the separator in a single cell. It is the figure which showed the main surface of the polymer electrolyte membrane in a single cell. It is a block diagram of the durability evaluation apparatus of the single cell which concerns on embodiment of this invention. It is the figure which showed the example of the setting of the node and element in a finite element model. It is a flowchart which shows the durability evaluation method of the single cell which concerns on embodiment of this invention. It is a flowchart which shows the durability evaluation method of the single cell which concerns on embodiment of this invention. It is a flowchart which shows the durability evaluation method of the single cell which concerns on embodiment of this invention. It is a figure which shows the structure of the durability evaluation program of the single cell which concerns on this invention. It is sectional drawing of the single cell used in the Example. It is the graph of the stress of the calculated polymer electrolyte membrane. It is the graph of the stress of the calculated polymer electrolyte membrane.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Single cell, 10 ... Polymer electrolyte membrane, 11 ... Electrode, 12 ... Separator, 13 ... Gas seal material, 14 ... Manifold, 21 ... Gas flow path, 30 ... Single cell durability evaluation apparatus, 31 ... Reception part 32 ... Model generation unit 33 ... Moisture distribution calculation unit 34 ... Strain / stress calculation unit 35 ... Equivalent stress calculation unit 36 ... Evaluation value deriving unit 37 ... Output unit 38 ... Judgment unit 40 ... Input device 50 ... Recording medium, 50a ... Program storage area, 51 ... Durability evaluation program, 51a ... Main module, 51b ... Reception module, 51c ... Model generation module, 51d ... Moisture distribution calculation module, 51e ... Strain / stress calculation module, 51f: Equivalent stress calculation module, 51g: Evaluation value derivation module, 51h: Output module.

Claims (11)

In the information processing apparatus, two polymer electrolyte membranes, two plate-like electrodes provided on both sides of the polymer electrolyte membrane, and two groove-like gas flow paths for supplying gas to the electrodes are formed. A single cell durability evaluation method for evaluating the durability of a single cell of a fuel cell comprising a plate-shaped separator and a sealing material for sealing a side surface of the electrode,
An accepting step for accepting input of parameters relating to the single cell;
A model generation step for generating a finite element model of the single cell divided into a plurality of elements based on the parameters received in the reception step;
Moisture distribution that calculates the moisture distribution of the polymer electrolyte membrane in the finite element model generated in the model generation step based on the boundary condition of the moisture distribution included in the parameter received in the reception step by a finite element method A calculation step;
Each element of the polymer electrolyte membrane is calculated from the moisture distribution calculated in the moisture distribution calculation step and the water absorption linear expansion coefficient and elastic modulus of the polymer electrolyte membrane included in the parameters received in the receiving step. Strain / stress calculation step for calculating the strain and stress of the finite element method,
An equivalent stress calculation step for calculating an equivalent stress in each of the elements from the stress in each of the elements calculated in the strain / stress calculation step;
An evaluation value deriving step for deriving an evaluation value for evaluating the durability of the single cell from the equivalent stress in each of the elements calculated in the equivalent stress calculating step;
An output step of outputting the evaluation value derived in the evaluation value deriving step;
Durability evaluation method including In the evaluation value deriving step, an average value S _av of equivalent stress of elements in an effective power generation region related to an electric reaction in the polymer electrolyte membrane among elements for which the equivalent stress is calculated in the equivalent stress calculating step is derived. Extracting the element in the ineffective power generation region other than the effective power generation region in the polymer electrolyte membrane in which the equivalent stress is c × S _av or more with respect to the set coefficient c of 1 or more, and the extracted element The method for evaluating durability of a single cell according to claim 1, wherein the evaluation value is derived from a value of the total volume _{Vz by} a predetermined formula. In the evaluation value deriving step, from the values of the total volume V _z , the volume V 0 of the polymer electrolyte membrane, the volume V _y of the effective power generation region in the polymer electrolyte membrane, and the thickness d of the polymer electrolyte membrane, 3. The method of evaluating durability of a single cell according to claim 2, wherein α derived from 1 and β derived from Equation 2 are used as the evaluation values.

  The method of evaluating durability of a single cell according to claim 2 or 3, wherein the coefficient c is 1.2.   The durability evaluation of a single cell according to any one of claims 1 to 4, wherein, in the model generation step, the finite element model having a node in a gas flow path formed in the separator is generated. Method.   The single cell durability evaluation method according to any one of claims 1 to 5, wherein, in the equivalent stress calculation step, the equivalent stress is calculated using a Mises equivalent stress formula.   It is determined whether or not the evaluation value derived in the evaluation value deriving step has converged. When it is determined that the evaluation value has converged, the evaluation value is output in the output step. The convergence determination step of generating the finite element model again by changing the number of nodes of the element of the single cell finite element model and deriving the evaluation value is further included. Evaluation method of single cell durability.   It is determined whether or not the evaluation value derived in the evaluation value deriving step satisfies a preset end condition. If it is determined that the evaluation value is satisfied, the evaluation value is output in the output step and is not satisfied. If it is determined that, the method further includes a condition determination step of generating the finite element model again based on a parameter different from the parameter related to the evaluation value derivation and deriving the evaluation value. The method for evaluating durability of a single cell according to one item. A polymer electrolyte membrane, two plate-like electrodes provided on both sides of the polymer electrolyte membrane, and two plate-like separators each having a groove-like gas flow path for supplying gas to the electrodes A single cell durability evaluation device for evaluating the durability of a single cell of a fuel cell comprising a sealing material for sealing the side surface of the electrode,
Receiving means for receiving input of parameters relating to the single cell;
Model generating means for generating a finite element model of the single cell divided into a plurality of elements based on the parameters received by the receiving means;
Moisture distribution for calculating the moisture distribution of the polymer electrolyte membrane in the finite element model generated by the model generating unit based on the boundary condition of the moisture distribution included in the parameter received by the receiving unit by the finite element method Calculation means;
Each element of the polymer electrolyte membrane is calculated from the moisture distribution calculated by the moisture distribution calculating means and the water absorption linear expansion coefficient and elastic modulus of the polymer electrolyte membrane included in the parameters received by the receiving means. Strain and stress calculation means for calculating the strain and stress of the finite element method,
Equivalent stress calculating means for calculating equivalent stress in each of the elements from the stress in each of the elements calculated by the strain / stress calculating means;
Evaluation value deriving means for deriving an evaluation value for evaluating the durability of the single cell from the equivalent stress in each of the elements calculated by the equivalent stress calculating means;
Output means for outputting the evaluation value derived by the evaluation value deriving means;
A durability evaluation apparatus comprising: Two information processing devices are provided with a polymer electrolyte membrane, two plate-like electrodes provided on both sides of the polymer electrolyte membrane, and two groove-like gas passages for supplying gas to the electrodes. A single cell durability evaluation program for performing a process for evaluating the durability of a single cell of a fuel cell including a plate-like separator and a sealing material for sealing the side surface of the electrode,
In the information processing apparatus,
An acceptance process for accepting input of parameters relating to the single cell;
A model generation process for generating a finite element model of the single cell divided into a plurality of elements based on the parameters received by the reception process;
Moisture distribution for calculating the moisture distribution of the polymer electrolyte membrane in the finite element model generated by the model generation process based on the boundary condition of the moisture distribution included in the parameter received by the reception process by the finite element method Calculation processing,
Each element of the polymer electrolyte membrane is calculated from the moisture distribution calculated by the moisture distribution calculation process and the water absorption linear expansion coefficient and elastic modulus of the polymer electrolyte membrane included in the parameters received by the receiving process. Strain and stress calculation processing for calculating strain and stress of the finite element method;
An equivalent stress calculation process for calculating an equivalent stress in each of the elements from the stress in each of the elements calculated by the strain / stress calculation process;
An evaluation value derivation process for deriving an evaluation value for evaluating the durability of the single cell from the equivalent stress in each of the elements calculated by the equivalent stress calculation process;
An output process for outputting the evaluation value derived by the evaluation value derivation process;
Durability evaluation program to execute. A polymer electrolyte membrane, two plate-like electrodes provided on both sides of the polymer electrolyte membrane, and two plate-like separators each having a groove-like gas flow path for supplying gas to the electrodes 4. A single cell of a fuel cell comprising a sealing material for sealing the side surface of the electrode, wherein the coefficient c is 1.2, according to the durability evaluation method for a single cell according to claim 3. A single cell of a fuel cell in which α is in a range of 0 [mm ² ] to 50.0 [mm ² ] and β is in a range of 0 to 0.01 in terms of evaluation value.

Images