A multiphysics field online testing device and method for fuel cells

Abstract

This invention relates to an online multiphysics field testing device and method for fuel cells, comprising a multiphysics field measurement plate, a separator, and a multiphysics field measurement plate stacked sequentially. The multiphysics field measurement plate has an array of multiple partitions along its surface and three layers with different functions along its thickness. The upper layer has a cathode gas flow field, with a first conductive metal insulated from each other on the flow channel ridges of the cathode gas flow field. The middle layer has an array of resistors and channels connecting the two ends of the resistors. The lower layer has a second conductive metal. A first current channel and a second current channel are arranged between the upper and lower layers, with the first and second current channels staggered and one end insulated from the conductive metal. The resistors are connected to the first and second current channels. Compared with existing technologies, this invention can replace bipolar plates and be installed at any cell to perform online measurement of the multiphysics field distribution of the fuel cell stack, offering flexible testing capabilities.

Description

Technical Field

[0001] This invention belongs to the field of fuel cell technology and relates to a multi-physics field online testing device and method for fuel cells. Background Technology

[0002] Proton exchange membrane fuel cells (PEMFCs) are a promising electrochemical energy conversion device that directly converts the chemical energy stored in fuel into electrical energy through electrochemical reactions. To meet the requirements for output voltage and power, fuel cells typically consist of multiple bipolar plates and membrane electrode assemblies connected in series to form a stack, with a single-cell reaction area reaching 200-500 cm². 2 The internal reaction of a fuel cell involves multiple physical fields such as temperature, humidity, and current density. The large reaction area often causes uneven distribution of these physical fields within the cell, leading to problems such as water blockage, dryness, and starvation of the anode and cathode. At the same time, there are performance differences between different individual cells in the fuel cell stack, and a cell may fail during operation. Therefore, obtaining information on the distribution of multiple physical fields in each cell of a fuel cell is of great guiding significance for fuel cell performance analysis and fault diagnosis.

[0003] The uniformity of the fuel cell reaction is closely related to the distribution of various physical fields within it, such as temperature, humidity, current density, and impedance. Currently, there are several research methods for measuring the distribution of these internal physical fields in fuel cells: finite element analysis requires massive computational power, demands sophisticated models, and is computationally inefficient; data-driven prediction of the distribution requires a large amount of fuel cell operating data, and even sporadic failures are difficult to predict accurately; in contrast, using an embedded in-situ online measurement system to measure the multiphysics of fuel cells yields more reliable results and has greater practical value.

[0004] Chinese patent CN110780213A discloses a current density detection composite plate, which measures a relatively single physical quantity; Chinese patents CN109301289A and CN103245920A disclose testing devices for temperature and pressure, and for current density, temperature, and impedance, respectively, but these devices are only applicable to single cells, which is quite different from the application scenario of multiple cells connected in series in a fuel cell stack; Chinese patent CN113030736A discloses an integrated measuring equipment for multiple physical quantities such as temperature, current density, humidity, and impedance, but the testing device is connected to the fuel cell end plate and is only applicable to the outermost cell of the fuel cell stack, and cannot obtain the condition of the cells in the middle of the stack.

[0005] Furthermore, the physical field distribution of various sensors on the embedded measurement board differs from that of the membrane electrode assembly in the fuel cell, and the heating of internal components on the measurement board causes localized hot spots, affecting the measurement accuracy of various physical quantities such as current density. Measuring the physical field distribution of a large-area fuel cell inevitably involves numerous measurement zones. Each additional physical quantity measured doubles the number of signals, placing high demands on the acquisition capabilities of the signal acquisition equipment. Given the limited number of channels in the signal acquisition equipment, how to simultaneously measure multiple zones and multiple physical fields of a large-area fuel cell using existing signal acquisition equipment is a pressing problem that needs to be solved.

[0006] Patent CN111308359A discloses a multifunctional online testing system for large-area fuel cells, including a multifunctional measuring board, a first data acquisition module, an excitation generator, a load circuit, and a computer. The multifunctional measuring board is mounted on the fuel cell as a cathode or anode plate. The load circuit connects the multifunctional measuring board to another single plate of the fuel cell corresponding to the multifunctional measuring board. The excitation generator is connected between the multifunctional measuring board and the single plate. The multifunctional measuring board includes multiple independent test zones, each with several sensor measurement holes. The sensors are connected to the first data acquisition module. The plates of the independent test zones are connected to the excitation generator and the load circuit, respectively. The computer is connected to the first data acquisition module and the excitation generator. However, the main body of this patent lacks related cooling water channels, and the current collected cannot be conducted to the next cell, limiting the use of the measuring board in large-area multi-cell stacks. Drilling holes in the PCB board to embed sensors requires high sealing and is difficult to process. Furthermore, this patent separates impedance from other physical signals and uses two different switches to control signal acquisition, significantly increasing the complexity and control difficulty of the system.

[0007] Patent CN117174963A discloses an in-situ monitoring device for multiple physical quantities in a proton exchange membrane fuel cell, comprising, from left to right, a cathode end plate, a cathode insulating plate, a cathode test plate, a membrane electrode assembly, an anode test plate, an anode insulating plate, and an anode end plate, all sequentially attached and assembled. The cathode and anode end plates are used to fix and encapsulate the entire proton exchange membrane fuel cell. The cathode and anode insulating plates are used to avoid direct contact between the end plates and the test plates, improving safety. Both the cathode and anode test plates can simultaneously monitor zoned current density and temperature and humidity distribution online. However, this patent also lacks cooling and current conduction methods for the next cell, making it unsuitable for fuel cell stacks with multiple cells connected in series. Furthermore, the patent uses optical fibers to measure temperature and humidity, requiring the fiber arrangement to be embedded in grooves on the measuring plate, resulting in complex manufacturing. Additionally, the use of standard resistors as the current density measuring element occupies a large area, making the structure less compact. Summary of the Invention

[0008] The purpose of this invention is to overcome at least one of the defects of the prior art by providing an online multiphysics field testing device and method for fuel cells. This invention can replace bipolar plates and be installed at any cell to perform online measurement of the multiphysics field distribution of the fuel cell stack, providing flexible testing.

[0009] The objective of this invention can be achieved through the following technical solutions:

[0010] One of the technical solutions of the present invention is to provide a fuel cell multiphysics field online testing device. The device includes a main body consisting of an electrical density impedance measuring plate, a separator, and a multiphysics field measuring plate stacked sequentially. A water flow field is provided on the electrical density impedance measuring plate and the multiphysics field measuring plate. An array of resistors is provided on the electrical density impedance measuring plate, and an array of sensors is provided on the multiphysics field measuring plate. The main body is placed on any cell at the end of the fuel cell stack or in the middle of the stack to realize the measurement of multiple physical fields such as current density, temperature, humidity, and impedance inside the flow channel or at the membrane electrode.

[0011] The electrical density impedance measuring plate is divided into multiple arrays in the plate surface direction and into three layers with different functions in the plate thickness direction. The upper surface layer is provided with a cathode gas flow field, and the flow channel ridge of the cathode gas flow field is provided with a first conductive metal that is insulated from each other. The middle layer is provided with an array of resistors and channels connecting the two ends of the resistors. The lower surface layer is provided with a second conductive metal.

[0012] A first current channel is provided between the first conductive metal of the flow channel ridge of the cathode gas flow field on the upper surface of the single-zone of the electrical density impedance measuring plate and the lower surface. No second conductive metal is provided at the connection between the lower surface and the first current channel for insulation. A second current channel is provided between the flow channel groove of the cathode gas flow field on the upper surface of the single-zone and the second conductive metal of the lower surface. The first current channel and the second current channel are arranged alternately and one end is insulated from the conductive metal. The resistor is connected to the first current channel and the second current channel, so that the current passes through the first conductive metal, the first current channel, the resistor, the second current channel and the second conductive metal in sequence.

[0013] Furthermore, each layer within each partition of the electrical density impedance measuring plate is provided with vents corresponding to the sensor, and the corresponding position of the vents is located in the flow channel groove of the cathode gas flow field.

[0014] The partition is divided into multiple arrays in the direction of the plate surface. It is conductive, and each partition has a mounting hole corresponding to the sensor. The size of the mounting hole is larger than that of the sensor.

[0015] As a preferred technical solution, a sealing groove is provided on the periphery of the electrical impedance measuring plate, and a sealing strip is filled in the sealing groove to seal and connect with the adjacent plate.

[0016] As a preferred technical solution, a sealing groove is provided on the periphery of the partition, and a sealing strip is filled into the sealing groove to seal and connect with the adjacent plate.

[0017] Furthermore, the multiphysics measurement plate is divided into multiple arrays in the plate surface direction and into three layers with different functions in the plate thickness direction. The upper surface layer is provided with an array of sensors and a third conductive metal. The middle layer is provided with channels connecting the two ends of the sensors. The lower surface layer is provided with a cooling water flow field, and a fourth conductive metal that is insulated from each other is provided on the flow channel ridge of the cooling water flow field.

[0018] Furthermore, a signal channel is provided between the cooling water flow field channels of the upper and lower surfaces within a single zone of the multiphysics measurement board. No third conductive metal is provided for insulation at the connection point between the upper surface and the signal channel. A third current channel is provided between the third conductive metal of the upper surface and the fourth conductive metal of the cooling water flow field ridge in the lower surface within the single zone. The signal channel and the third current channel are arranged in isolation. The two ends of the signal channel are insulated from the conductive metal and connected to the sensor, allowing the sensor to transmit the measurement signal to the intermediate layer output through the surrounding signal channels, and for current to be transmitted between the third and fourth conductive metals through the third current channel.

[0019] Furthermore, when the device is used for the middle battery of the stack, the main body is composed of an electrical density impedance measuring plate, a separator, a multiphysics field measuring plate and a single plate stacked in sequence. This main body is placed between a pair of membrane electrodes instead of bipolar plates, and the membrane electrodes are placed on the other side of the main body with bipolar plates.

[0020] When the device is used for the end cell of the fuel cell stack, the main body is composed of an electrical density impedance measurement plate, a separator and a multiphysics field measurement plate stacked in sequence. This main body is placed between the membrane electrode and the current collector instead of the bipolar plate. The membrane electrode is placed on the other side of the main body with the bipolar plate.

[0021] Furthermore, the single electrode plate is conductive, and cooling water flow field and anode gas flow field are respectively arranged on both sides.

[0022] As a preferred technical solution, a sealing groove is provided on the periphery of the single plate, and a sealing strip is filled into the sealing groove to seal and connect with the adjacent plate.

[0023] As a preferred technical solution, the current density measuring board and the multi-physics field measuring board are made of multilayer PCB board, the conductive metal is made of copper plating, the current channel and the signal channel are made of through holes, and the partition and the monopole plate are made of graphite plate or metal plate with good conductivity by machining.

[0024] As a preferred technical solution, the sensor is selected from one or more sensors for multiphysics fields of fuel cells, such as temperature and humidity sensors, oxygen concentration sensors, and endoscopes.

[0025] When the device is used in the middle battery of the stack, the battery current will flow sequentially through the membrane electrode, the first conductive metal on the upper surface of the electrical density impedance measurement plate, the first current channel, the resistor, the second current channel, the second conductive metal on the lower surface, the separator, the third conductive metal on the upper surface of the multiphysics field measurement plate, the third current channel, the fourth conductive metal on the lower surface, the single plate, and then reach the next membrane electrode.

[0026] When the device is used for the end battery of the fuel cell stack, the battery current flows sequentially through the membrane electrode, the first conductive metal on the upper surface of the electrical density impedance measurement plate, the first current channel, the resistor, the second current channel, the second conductive metal on the lower surface, the separator, the third conductive metal on the upper surface of the multiphysics field measurement plate, the third current channel, and the fourth conductive metal on the lower surface before directly entering the current collector.

[0027] The device contains a water vapor flow field, which ensures the normal water vapor supply to the battery.

[0028] The main body is equipped with a cathode gas flow field, a cooling water flow field, and an anode gas flow field, as well as a current conduction path that combines the flow fields. While performing multi-physics field measurements, it meets the operational requirements of current conduction and water and gas supply inside the stack, ensuring that the device can measure any cell inside or at the end of the stack.

[0029] Furthermore, the inlet and outlet structure of the water flow field is different from that of a normal electrode plate flow field. The introduction of the device will change the distribution of water and gas in the cell. The device selects the inlet form according to the change of the water flow field on the measuring plate compared with the normal electrode plate flow resistance, including a step structure or a distribution area flow channel, and adjusts the geometric dimensions of the step inlet or distribution area to reduce the influence of the device on the water flow field and the distribution of gas and cooling water at the two electrodes, and avoid the problem of uneven water and gas distribution caused by the embedding of the main body.

[0030] As a preferred technical solution, since the actual bipolar plate flow field has a draft angle, the flow resistance of the bipolar plate flow field is smaller than that of the measuring plate flow field. In order to compensate for the large flow resistance of the measuring plate, the inlet and outlet structures of the cathode gas flow field, cooling water flow field and anode gas flow field have eliminated the inlet step structure and adopted a planar rectangular distribution area flow channel to reduce the change in stack flow resistance caused by the device and the impact on the distribution of cathode gas, cooling water and anode gas inside the battery.

[0031] Furthermore, the device also includes a data acquisition module, a computer, and peripheral devices for a load and an excitation generator. The measurement signals from the electrical density impedance measurement board and the multiphysics field measurement board are imported into the data acquisition module and finally uploaded to the computer. The load and the excitation generator are connected to both ends of the stack. The computer processes the measurement signals, controls the load state, and controls the disturbance input of the excitation generator. The peripheral devices can correct the multiphysics field test signals obtained by the main body, thereby obtaining the true distribution of multiphysics fields in the membrane electrode region.

[0032] The device also includes peripheral equipment for a signal control switch. The signal control switch is located between the main body and the data acquisition module and is controlled by a computer. The measurement signals from the electrical density impedance measurement board and the multi-physics field measurement board are imported into the data acquisition module through the signal control switch. The computer controls the opening and closing of the signal control switch. The peripheral equipment can realize the sequential acquisition of data from different regions of the flow field or different physical fields, and realize the rapid measurement of large-area multi-physics fields.

[0033] The data acquisition module collects the voltage drop across the resistor in each section of the electrical density impedance measurement board, and the temperature and humidity of the reaction gas detected by the sensors in each section of the multiphysics measurement board passing through the pores of the electrical density impedance measurement board and the mounting holes of the partition. The voltage drop and temperature and humidity are then uploaded to the computer for correction and image processing to obtain the current density, temperature, and humidity distribution.

[0034] The data acquisition module acquires the voltage response between the first current channel in each partition and the anode of the bipolar plate on the other side of the membrane electrode on one side of the electrical density impedance measurement plate when the excitation generator is input to a disturbance. The voltage response is then transmitted to the computer for processing to obtain the partition impedance distribution.

[0035] The computer automatically adjusts the working state of the load based on the measured physical field distribution.

[0036] The signals measured by the main body are acquired by the data acquisition module after passing through the signal control switch and uploaded to the computer. After calculation, correction and visualization, they are presented to the user. At the same time, the computer adjusts the load of the fuel cell stack appropriately according to the measurement results to adapt to the current working condition of the fuel cell stack.

[0037] The computer calculates the partition current density based on the voltage drop uploaded by the data acquisition module, calculates the partition impedance based on the response signal, corrects the temperature and humidity measurement results of the test site to the temperature and humidity at the membrane electrode, and finally presents the test results to the user in an image format.

[0038] One of the technical solutions of the present invention is to provide a method for online testing of fuel cells using multiphysics fields. This method uses the aforementioned online multiphysics testing device for fuel cells and includes the following steps:

[0039] The computer corrects the current density signal of the resistor and the temperature signal of the sensor at high temperature to reduce the influence of resistor heating on current density measurement and the influence of sensor installation location on temperature measurement, and obtains the current density and temperature distribution of the membrane electrode reaction zone. The correction relationship comes from experimental calibration and analytical model calculation.

[0040] Current density testing: due to the thermal effect of the resistor, the actual temperature of the resistor during measurement is higher than the reaction temperature inside the fuel cell. The computer uses finite element analysis to obtain the relationship between the current density flowing through the resistor and the actual temperature of the resistor under specific battery reaction temperature and cooling water temperature conditions. It further obtains the relationship between the voltage drop across the resistor and the actual resistance value, thereby calculating the current density of the resistor in each zone.

[0041] Temperature testing: Due to the distance between the sensor installation location and the membrane electrode, there is a difference between the gas temperature reaching the measurement point and the membrane electrode temperature. The computer uses finite element analysis to obtain the relationship between the battery membrane electrode temperature t0, the temperature measured by the temperature and humidity sensor t1, and the cooling water temperature t2. Based on the temperature measured by the temperature and humidity sensor t1 and the cooling water temperature t2, the membrane electrode temperature t0 in each zone is calculated.

[0042] The partition impedance test involves applying sinusoidal micro-interference to each test partition of the fuel cell using an excitation generator. The data acquisition module collects the frequency response signals of each partition in real time, and the computer calculates the AC impedance of each partition based on the response signals.

[0043] Furthermore, when the number of acquisition channels is insufficient, the measurement signals in each zone can share a single acquisition channel. Users can control the opening and closing of signal control switches for various physical quantities via computer as needed to measure a certain physical quantity; or, the opening and closing sequence and alternation frequency of the signal control switches can be adjusted via computer to achieve sequential measurement of multiple physical fields in different regions of the flow field, ultimately completing the entire flow field test, while adjusting the refresh rate of the distribution image.

[0044] As a preferred technical solution, when the measured physical quantity signal is less than the number of channels of the data acquisition module, all signal control switches are closed; when the measured physical quantity signal is more than the number of channels of the data acquisition module, one acquisition channel connects multiple measurement signals, and the user controls the opening and closing of the signal control switch through a computer to realize the acquisition and measurement of specific physical quantity signals in a specific zone, or, by adjusting the signal control switch to cycle open and close, to realize the simultaneous measurement of all multi-physical fields of the fuel cell stack.

[0045] As a preferred technical solution, the data acquisition module has m channels and n partitions. When m>=4n, all signal control switches are closed, and the device simultaneously tests the current density, temperature, humidity, and impedance distribution of all partitions of the fuel cell stack. When m<4n, one acquisition channel connects to multiple measurement signals. The user can freely adjust the closing of the signal control switches via a computer to control the number of partitions and the types of physical quantities acquired by the data acquisition module. Alternatively, the user can adjust the opening and closing sequence and switching frequency of the signal control switches to control the update sequence and refresh frequency of the multiphysics visualization window.

[0046] This invention provides an online multi-physics field testing device for fuel cells, capable of online measurement of the non-uniform distribution of multiple physical fields such as current density, temperature, humidity, and high-frequency impedance inside a large-area fuel cell stack. The device utilizes a combination of flow field, current channel, and conductive metal configuration to ensure that its integration does not affect the original stack's functionality. Computer-based correction calculations reduce measurement site deviations and system errors caused by heat generation. Simultaneously, computer-controlled signals control the closing of switches to achieve simultaneous measurement of multiple physical quantities across multiple zones of a large-area fuel cell under limited data acquisition channels.

[0047] This invention, by combining water and airflow fields to alternately distribute current channels and conductive metals, allows for zoned measurement of the reaction state of any single cell within the fuel cell stack, overcoming the limitation of existing testing devices that can only be placed at the end of the stack. Simultaneously, by correcting the flow field structure and test data of the testing device, the membrane electrode reaction state can be obtained, improving the accuracy of the test results. The fuel cell multiphysics online testing device proposed in this invention features high integration, flexible testing sites, minimal impact on the fuel cell stack, and simple operation.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] (1) The present invention adopts a battery current conduction path design that combines flow field, which can replace the bipolar plate and be assembled at any battery cell to measure the multi-physical field distribution of fuel cell stack online, making the test flexible; at the same time, it considers the influence of embedded measurement board on the water and gas distribution of the stack and makes adjustments to the inlet and outlet of the flow field.

[0050] (2) The present invention adopts a multi-channel signal acquisition method with computer-controlled signal control switch to adjust the changes in the acquired signal, which can meet the signal acquisition needs of multiple zones and multiple physical fields when the signal acquisition equipment has fewer channels; at the same time, through computer calculation and analysis, the current density measurement error caused by resistor heating and the temperature measurement error caused by sensor position are corrected, thereby improving the measurement accuracy. Attached Figure Description

[0051] Figure 1This is a three-dimensional structural schematic diagram of the fuel cell multiphysics field online testing device in an embodiment of the present invention;

[0052] Figure 2 This is a schematic diagram of the front view structure of the electrical density impedance measuring plate in an embodiment of the present invention;

[0053] Figure 3 This is a schematic diagram of the structural modifications to the flow field inlet and outlet in an embodiment of the present invention;

[0054] Figure 4 This is a schematic diagram of the front view structure of the partition in an embodiment of the present invention;

[0055] Figure 5 This is a schematic diagram of the main structure of the temperature and humidity measuring plate in an embodiment of the present invention;

[0056] Figure 6 This is a schematic diagram of the main structure of the monopolar plate in an embodiment of the present invention;

[0057] Figure 7 This is a three-dimensional structural diagram of a single-section fuel cell multiphysics field online testing device in an embodiment of the present invention;

[0058] Figure 8 This is a schematic cross-sectional view of the fuel cell multiphysics field online testing device in an embodiment of the present invention;

[0059] Figure 9 This is a schematic diagram of the connection of the online multiphysics test device for fuel cells in the case of measuring the middle battery of the fuel cell stack in an embodiment of the present invention;

[0060] Figure 10 This is a schematic diagram of the connection of the fuel cell multiphysics online testing device in the case of battery measurement at the stack end in an embodiment of the present invention;

[0061] Figure 11 This is a temperature distribution diagram of the resistance during measurement in an embodiment of the present invention.

[0062] Explanation of markings in the diagram:

[0063] 1—Electrical density impedance measuring plate, 2—Separator, 3—Temperature and humidity measuring plate, 4—Monopolar plate, 5—Signal control switch, 6—Data acquisition module, 7—Computer, 8—Load, 9—Excitation generator, 10—Membrane electrode;

[0064] 11—Cathode gas flow field; 12-1—First conductive metal; 12-2—Second conductive metal; 12-3—Third conductive metal; 12-4—Fourth conductive metal; 13—Sealing groove; 14—Resistor; 15-1—First current channel; 15-2—Second current channel; 15-3—Third current channel; 16—Signal channel; 17—Vent; 18—Mounting hole; 19—Temperature and humidity sensor; 20—Cooling water flow field; 21—Anode gas flow field;

[0065] 22—Bipolar plate, 23—Current collector. Detailed Implementation

[0066] The present invention will now be described in detail with reference to specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0067] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first," "second," "third," etc., used to describe a common object only indicate different instances of the same object, and do not imply that the objects described in this way must be in a given order, whether temporally, spatially, sequentially, or in any other way.

[0068] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0069] Example:

[0070] A multiphysics online testing device for fuel cells, such as Figure 1 As shown, the main body includes an electrical impedance measuring plate 1, a partition plate 2, and a temperature and humidity measuring plate 3 stacked in sequence.

[0071] Water and airflow fields are set on the electrical impedance measuring plate 1 and the temperature and humidity measuring plate 3. The electrical impedance measuring plate 1 is equipped with an array of resistors 14, and the temperature and humidity measuring plate 3 is equipped with an array of temperature and humidity sensors 19.

[0072] The main body can be placed at the end of the battery or at any cell in the middle of the stack to achieve the measurement of multiple physical fields such as current density, temperature, humidity, and impedance inside the flow channel or at the membrane electrode.

[0073] like Figure 2 , Figure 7 and Figure 8 As shown, the electrical density impedance measurement plate 1 has an array of multiple sections in the plate surface direction and three layers with different functions in the plate thickness direction.

[0074] A cathode gas flow field 11 is provided on the upper side of the upper surface layer, and a first conductive metal 12-1 that is insulated from each other is provided on the ridge of the flow channel of the cathode gas flow field 11.

[0075] An array of resistors 14 is provided on the upper side of the intermediate layer, along with channels connected to both ends of the resistors 14.

[0076] A second conductive metal 12-2 is provided on the lower side of the lower surface layer;

[0077] In the single-zone of the electrical density impedance measuring plate 1, a first current channel 15-1 is provided between the first conductive metal 12-1 of the flow channel ridge of the cathode gas flow field 11 on the upper surface layer and the lower surface layer. No second conductive metal 12-2 is provided at the connection between the lower surface layer and the first current channel 15-1 for insulation.

[0078] A second current channel 15-2 is provided between the flow channel groove of the cathode gas flow field 11 on the upper surface layer and the second conductive metal 12-2 on the lower surface layer within the single zone.

[0079] The first current channel 15-1 and the second current channel 15-2 are arranged alternately and one end is insulated from the conductive metal. The resistor 14 is connected to the first current channel 15-1 and the second current channel 15-2, so that the current passes through the first conductive metal 12-1, the first current channel 15-1, the resistor 14, the second current channel 15-2 and the second conductive metal 12-2 in sequence.

[0080] Each section and layer of the electrical impedance measurement plate 1 has vents 17 corresponding to the temperature and humidity sensor 19. The vents 17 are located in the flow channel groove of the cathode gas flow field 11.

[0081] A sealing groove 13 is provided on the outer perimeter, and a sealing strip is filled into the sealing groove 13 to seal and connect with the adjacent plate.

[0082] In this embodiment, the resistor 14, the first current channel 15-1, the second current channel 15-2 and the air hole 17 of the single-zone internal electrical density impedance measuring plate 1 are all provided at one location.

[0083] like Figure 4 , Figure 7 and Figure 8 As shown, the partition 2 has an array of multiple sections in the direction of the plate surface, which are conductive. Each section has a mounting hole 18 corresponding to the temperature and humidity sensor 19. The size of the mounting hole 18 is larger than that of the temperature and humidity sensor 19.

[0084] A sealing groove 13 is provided on the outer perimeter, and a sealing strip is filled into the sealing groove 13 to seal and connect with the adjacent plate.

[0085] In this embodiment, the partition 2 in the single section has one mounting hole 18;

[0086] like Figure 5 , Figure 7 and Figure 8 As shown, the temperature and humidity measuring plate 3 has an array of multiple zones on its surface and three layers with different functions on its thickness.

[0087] The upper surface layer is equipped with an array of temperature and humidity sensors 19 and a third conductive metal 12-3.

[0088] The upper side of the middle layer has channels connecting the two ends of the temperature and humidity sensor 19.

[0089] A cooling water flow field 20 is provided on the lower side of the lower surface layer, and a fourth conductive metal 12-4 that is insulated from each other is provided on the ridge of the flow channel of the cooling water flow field 20.

[0090] A signal channel 16 is provided between the cooling water flow field 20 of the upper and lower surfaces within a single zone of the temperature and humidity measuring plate 3. No third conductive metal 12-3 is provided for insulation at the connection point between the upper surface and the signal channel 16.

[0091] A third current channel 15-3 is provided between the third conductive metal 12-3 on the upper surface of the single zone and the fourth conductive metal 12-4 on the flow channel ridge of the cooling water flow field 20 on the lower surface.

[0092] The signal channel 16 and the third current channel 15-3 are arranged in isolation. The two ends of the signal channel 16 are insulated from the conductive metal and connected to the temperature and humidity sensor 19, so that the temperature and humidity sensor 19 transmits the measurement signal to the intermediate layer output through the surrounding signal channel 16, and the third conductive metal 12-3 and the fourth conductive metal 12-4 transmit current through the third current channel 15-3.

[0093] In this embodiment, the temperature and humidity sensor 19 of the temperature and humidity measuring board 3 in a single zone is provided at one location, and the signal channel 16 and the third current channel 15-3 are provided at two locations.

[0094] like Figures 8 to 10As shown, when the device is used for the battery in the middle of the stack, the main body is composed of the electrical density impedance measuring plate 1, the separator 2, the temperature and humidity measuring plate 3 and the single plate 4 stacked in sequence. The main body replaces the bipolar plate 22 and is placed between a pair of membrane electrodes 10. The membrane electrode 10 is placed on the other side of the main body with the bipolar plate 22.

[0095] When the device is used for the end battery of the stack, the electrical density impedance measuring plate 1, the separator 2 and the temperature and humidity measuring plate 3 are stacked in sequence to form the main body. The main body replaces the bipolar plate 22 and is placed between the membrane electrode 10 and the current collector 23. The membrane electrode 10 is placed on the other side of the main body with the bipolar plate 22.

[0096] like Figures 6 to 8 As shown, the single-plate 4 is conductive, and cooling water flow field 20 and anode gas flow field 21 are respectively arranged on both sides.

[0097] A sealing groove 13 is provided on the outer perimeter, and a sealing strip is filled into the sealing groove 13 to seal and connect with the adjacent plate.

[0098] The current density measuring board 1 and the temperature and humidity measuring board 3 are made of multilayer PCB board, the conductive metal is made of surface copper, the resistor 14 is made of thickened copper wire, the temperature and humidity sensor 19 is a SHT31-ARP-B type sensor produced by SENSIRION, the current channel and signal channel 16 are made of through holes, and the partition 2 and the single plate 4 are made of graphite plate or metal plate with good conductivity by machining. In this embodiment, graphite plate is preferred.

[0099] The types of sensors installed are not limited to temperature and humidity sensors; oxygen concentration sensors, endoscopes, or other sensors targeting the multiphysics field of fuel cells can also be placed.

[0100] When the device is used in the middle battery of the stack, the battery current will flow sequentially through the membrane electrode 10, the first conductive metal 12-1 on the upper surface of the electrical density impedance measuring plate 1, the first current channel 15-1, the resistor 14, the second current channel 15-2, the second conductive metal 12-2 on the lower surface, the separator 2, the third conductive metal 12-3 on the upper surface of the temperature and humidity measuring plate 3, the third current channel 15-3, the fourth conductive metal 12-4 on the lower surface, and the monopole plate 4, and then reach the next membrane electrode 10;

[0101] When the device is used for the end battery of the stack, the battery current will flow sequentially through the membrane electrode 10, the first conductive metal 12-1 on the upper surface of the electrical density impedance measuring plate 1, the first current channel 15-1, the resistor 14, the second current channel 15-2, the second conductive metal 12-2 on the lower surface, the separator 2, the third conductive metal 12-3 on the upper surface of the temperature and humidity measuring plate 3, the third current channel 15-3, and the fourth conductive metal 12-4 on the lower surface, and then directly enter the current collector 23;

[0102] The device contains a water vapor flow field, which ensures the normal water vapor supply to the battery.

[0103] The main body is equipped with a cathode gas flow field 11, a cooling water flow field 20, and an anode gas flow field 21, as well as a current conduction path that combines the flow fields. While performing multi-physics field measurements, it meets the operational requirements of current conduction and water and gas supply inside the stack, ensuring that the device can measure any cell inside or at the end of the stack.

[0104] The inlet and outlet structure of the water flow field is different from that of ordinary electrode plate flow field. The introduction of the device will change the distribution of water and gas in the cell. The device selects the inlet form according to the change of water flow field on the measuring plate compared with the normal electrode plate flow resistance, including step structure or distribution area flow channel, and adjusts the geometric dimensions of step inlet or distribution area to reduce the influence of the device on water flow field and distribution of gas and cooling water on the two electrodes, and avoid the problem of uneven water and gas distribution caused by the embedding of the main body.

[0105] In this embodiment, as Figure 3 As shown, due to the draft angle of the actual bipolar plate 22 flow field, the flow resistance of the bipolar plate 22 flow field is smaller than that of the measuring plate flow field. In order to compensate for the large flow resistance of the measuring plate, the inlet and outlet structures of the cathode gas flow field 11, cooling water flow field 20 and anode gas flow field 21 have eliminated the step structure and adopted a planar rectangular distribution area flow channel to reduce the change in stack flow resistance caused by the device and the impact on the distribution of cathode gas, cooling water and anode gas inside the battery.

[0106] like Figure 9 and Figure 10 As shown, the device also includes a data acquisition module 6, a computer 7, a load 8, and peripheral devices such as an excitation generator 9. The measurement signals from the electrical density impedance measuring board 1 and the temperature and humidity measuring board 3 are imported into the data acquisition module 6 and finally uploaded to the computer 7. The load 8 and the excitation generator 9 are connected to both ends of the fuel cell stack. The computer 7 processes the measurement signals, controls the state of the load 8, and controls the disturbance input of the excitation generator 9. The peripheral devices can correct the multiphysics test signals obtained by the main body, thereby obtaining the true distribution of the multiphysics in the membrane electrode 10 region. In the figure, the dotted lines represent signal lines, and the solid lines represent wires.

[0107] The data acquisition module 6 collects the voltage drop across the resistor 14 in each section of the electrical density impedance measuring board 1 and the temperature and humidity of the reaction gas detected by the temperature and humidity sensor 19 in each section of the temperature and humidity measuring board 3, which passes through the air hole 17 of the electrical density impedance measuring board 1 and the mounting hole 18 of the partition 2. The voltage drop and temperature and humidity are then uploaded to the computer 7 for correction and image processing to obtain the current density, temperature and humidity distribution.

[0108] The data acquisition module 6 acquires the voltage response between the first current channel 15-1 in each partition and the anode of the bipolar plate 22 on the other side of the membrane electrode 10 on the upper side of the electrical density impedance measuring plate 1 when the excitation generator 9 is disturbed. The voltage response is then transmitted to the computer 7 for processing to obtain the partition impedance distribution.

[0109] Computer 7 automatically adjusts the working state of load 8 based on the measured physical field distribution.

[0110] Data acquisition module 6 uses a PXIe series data acquisition card chassis manufactured by NI, and load 8 uses a conventional electronic load manufactured by ITECH.

[0111] The device also includes peripheral equipment for signal control switch 5. Signal control switch 5 is located between the main body and the data acquisition module 6 and is controlled by computer 7. The measurement signals of the electrical density impedance measuring plate 1 and the temperature and humidity measuring plate 3 are imported into the data acquisition module 6 through signal control switch 5. Computer 7 controls the opening and closing of signal control switch 5. Peripheral equipment can realize the sequential acquisition of data of different regions of the flow field or different physical fields, and realize the rapid measurement of large area multi-physical fields.

[0112] The signal measured by the main body is acquired by the data acquisition module 6 after passing through the signal control switch 5 and uploaded to the computer 7. After calculation, correction and visualization, it is presented to the user. At the same time, the computer 7 makes appropriate adjustments to the load 8 of the fuel cell stack according to the measurement results to adapt to the current working condition of the fuel cell stack.

[0113] Computer 7 calculates the partition current density based on the voltage drop uploaded by data acquisition module 6, calculates the partition impedance based on the response signal, corrects the temperature and humidity measurement results of the test site to the temperature and humidity at membrane electrode 10, and finally presents the test results to the user in a graphical format.

[0114] A method for online multiphysics testing of fuel cells, using the aforementioned online multiphysics testing device for fuel cells, comprises the following specific steps:

[0115] Computer 7 corrects the current density signal of resistor 14 and the temperature signal of temperature and humidity sensor 19 at high temperature to reduce the influence of the heating of resistor 14 on the current density measurement and the influence of the installation position of temperature and humidity sensor 19 on the temperature measurement, and obtains the current density and temperature distribution of the reaction zone of membrane electrode 10. The correction relationship comes from experimental calibration and analytical model calculation.

[0116] In the current density test, due to the thermal effect of resistor 14, the actual temperature of resistor 14 is higher than the reaction temperature inside the fuel cell during the measurement. The computer 7 obtains the correspondence between the current density flowing through resistor 14 and the actual temperature of resistor 14 under specific battery reaction temperature and cooling water temperature conditions through finite element calculation. It further obtains the correspondence between the voltage drop across resistor 14 and the actual resistance value of resistor 14, thereby calculating the current density of resistor 14 in each zone.

[0117] Temperature testing: Due to the distance between the installation location of the temperature and humidity sensor 19 and the membrane electrode 10, the gas temperature reaching the measurement point differs from the temperature of the membrane electrode 10. The computer 7 calculates the relationship between the battery membrane electrode 10 temperature t0, the temperature measured by the temperature and humidity sensor 19 t1, and the cooling water temperature t2 through finite element analysis. Based on the temperature measured by the temperature and humidity sensor 19 t1 and the cooling water temperature t2, the membrane electrode 10 temperature t0 in each zone is calculated.

[0118] In this embodiment, resistor 14 is a 3mm long and 0.5mm wide copper wire, with 0.5mm copper wires connected to both ends for conduction. The conditions are: membrane electrode 10 temperature 95℃, cooling water temperature 80℃, and current density CD = 2A / cm². 2 Under the given conditions, the temperature condition of resistor 14 is as follows: Figure 11 As shown, computer 7 uses finite element analysis to obtain the temperature of resistor 14 under different current densities. The relationship between copper resistance and temperature follows R = ρ0[1-α(T-T0)]L / A, where ρ0 is the conductivity of copper at the reference temperature T0, T is the current temperature, α is the temperature coefficient of copper, L is the length of resistor 14, and A is the cross-sectional area of ​​resistor 14. Based on this, the relationship between current density CD and resistance R of resistor 14 is obtained as CD = φ(R). The voltage drop of resistor 14 is V = R × CD × S, where S is the area of ​​the partition. Combining these, the relationship between current density CD and voltage drop V across resistor 14 is obtained as CD = Φ(V). Under the conditions of 95℃ for the inner membrane electrode 10 and 80℃ for the cooling water in each partition, the corresponding relationship between current density CD and voltage drop V of resistor 14 is CD = -5E-07V. 3 -0.0001V 2 +0.0611V -0.0013;

[0119] In this embodiment, according to Newton's law of cooling, q = h × (T) f -T s ) and the one-dimensional steady-state heat conduction equation T(x)=T s +q×x / k, where h is the convective heat transfer coefficient, k is the thermal conductivity, and T f The fluid temperature is related to the membrane electrode 10 temperature t0. sThe solid surface temperature is t0, which is related to the cooling water temperature t2. x represents the conduction distance, which is related to the distance from the membrane electrode 10 to the temperature and humidity sensor 19. Therefore, there is a linear relationship between the membrane electrode 10 temperature t0, the temperature measured by the temperature and humidity sensor 19 t1, and the cooling water temperature t2. The gas flow rate in a single flow channel is 7 × 10⁻⁶. -6 Under the condition of kg / s, the computer 7 obtained the linear relationship between the three temperatures under different gas flow rates through finite element calculation as t0-t2=0.3851(t1-t2)+0.0651. The temperature t0 of the membrane electrode 10 in each zone can be obtained by measuring the temperature t1 and the cooling water temperature t2 of the temperature and humidity sensor 19.

[0120] For the partition impedance test, a sinusoidal micro-interference is applied to each test partition of the fuel cell by the excitation generator 9, and the data acquisition module 6 collects the frequency response signal of each partition in real time. The computer 7 calculates the AC impedance of each partition based on the response signal.

[0121] When the number of acquisition channels is insufficient, the four types of measurement signals in each zone can share one acquisition channel. Users can control the opening and closing of the signal control switches 5 of various physical quantities through the computer 7 to achieve the measurement of a certain physical quantity. The opening and closing sequence and alternation frequency of the signal control switches 5 can also be adjusted through the computer 7 to achieve the sequential measurement of multiple physical fields in different regions of the flow field, and finally complete the entire flow field test, while adjusting the refresh frequency of the distribution image.

[0122] When the measured physical quantity signal is less than the number of channels of the data acquisition module 6, all signal control switches 5 are closed; when the measured physical quantity signal is more than the number of channels of the data acquisition module 6, one acquisition channel connects multiple measurement signals. The user can control the opening and closing of the signal control switch 5 through the computer 7 to realize the acquisition and measurement of specific physical quantity signals in a specific zone. Alternatively, the user can adjust the signal control switch 5 to cycle open and close to realize the simultaneous measurement of all multi-physical fields of the fuel cell stack.

[0123] The data acquisition module 6 has m channels and n partitions. When m >= 4n, all signal control switches 5 are closed. At this time, the device simultaneously tests the current density, temperature, humidity, and impedance distribution of all partitions of the fuel cell stack. When m < 4n, one acquisition channel connects to multiple measurement signals. The user can freely adjust the closing of the signal control switches 5 through the computer 7 to control the number of partitions and the type of physical quantity acquired by the data acquisition module 6. The user can also control the update order and refresh frequency of the multiphysics visualization window by adjusting the opening and closing sequence and switching frequency of the signal control switches 5.

[0124] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A multiphysics online testing device for fuel cells, characterized in that, The device comprises a main body consisting of an electrical density impedance measuring plate (1), a partition plate (2), and a multiphysics field measuring plate stacked in sequence. Water and air flow fields are provided on the electrical density impedance measuring plate (1) and the multiphysics field measuring plate. An array of resistors (14) is provided on the electrical density impedance measuring plate (1). An array of sensors is provided on the multiphysics field measuring plate. The main body is placed on any cell at the end of the stack or in the middle of the stack. The electrical density impedance measuring plate (1) is divided into multiple partitions in the plate surface direction and three layers with different functions in the plate thickness direction. The upper surface layer is provided with a cathode gas flow field (11), and the flow channel ridge of the cathode gas flow field (11) is provided with a first conductive metal (12-1) that is insulated from each other. The middle layer is provided with an array of resistors (14) and a channel connecting the two ends of the resistors (14). The lower surface layer is provided with a second conductive metal (12-2). A first current channel (15-1) is provided between the first conductive metal (12-1) of the flow channel ridge of the cathode gas flow field (11) on the upper surface of the single-zone of the electrical density impedance measuring plate (1) and the lower surface. No second conductive metal (12-2) is provided at the connection between the lower surface and the first current channel (15-1) for insulation. A second current channel (15-2) is provided between the flow channel groove of the cathode gas flow field (11) on the upper surface of the single-zone and the second conductive metal (12-2) on the lower surface. The first current channel (15-1) and the second current channel (15-2) are arranged alternately and one end is insulated from the conductive metal. The resistor (14) is connected to the first current channel (15-1) and the second current channel (15-2).

2. The fuel cell multiphysics online testing device according to claim 1, characterized in that, The electrical density impedance measuring plate (1) has air holes (17) corresponding to the sensor on each layer in each partition, and the corresponding position of the air hole (17) is located in the flow channel groove of the cathode gas flow field (11). The partition (2) is divided into multiple arrays in the direction of the plate surface. It is conductive, and each partition has a mounting hole (18) corresponding to the sensor. The size of the mounting hole (18) is larger than that of the sensor.

3. The fuel cell multiphysics online testing device according to claim 1, characterized in that, The multiphysics measurement board has an array of multiple partitions in the board surface direction and three layers with different functions in the board thickness direction. The upper surface layer is provided with an array of sensors and a third conductive metal (12-3). The middle layer is provided with channels connecting the two ends of the sensors. The lower surface layer is provided with a cooling water flow field (20). The flow ridge of the cooling water flow field (20) is provided with a fourth conductive metal (12-4) that is insulated from each other.

4. The fuel cell multiphysics online testing device according to claim 3, characterized in that, A signal channel (16) is provided between the flow channel grooves of the cooling water flow field (20) of the upper and lower surfaces within a single zone of the multiphysics field measurement plate. No third conductive metal (12-3) is provided at the connection between the upper surface and the signal channel (16) for insulation. A third current channel (15-3) is provided between the third conductive metal (12-3) of the upper surface and the fourth conductive metal (12-4) of the flow channel ridge of the cooling water flow field (20) of the lower surface within a single zone. The signal channel (16) and the third current channel (15-3) are arranged in isolation. The two ends of the signal channel (16) are insulated from the conductive metal and connected to the sensor.

5. The online multiphysics testing device for fuel cells according to claim 1, characterized in that, When the device is used in the middle battery of the stack, the main body is composed of the electrical density impedance measuring plate (1), the separator (2), the multiphysics field measuring plate and the monopole plate (4) stacked in sequence. The main body replaces the bipolar plate (22) and is placed between a pair of membrane electrodes (10). The membrane electrodes (10) are placed on the other side of the main body with the bipolar plate (22). When the device is used for the end battery of the stack, the electrical density impedance measuring plate (1), the separator (2) and the multiphysics field measuring plate are stacked in sequence to form the main body. The main body replaces the bipolar plate (22) and is placed between the membrane electrode (10) and the current collector (23). The membrane electrode (10) is placed on the other side of the main body with the bipolar plate (22).

6. The fuel cell multiphysics online testing device according to claim 5, characterized in that, The single plate (4) is conductive, and cooling water flow field (20) and anode gas flow field (21) are respectively provided on both sides.

7. The fuel cell multiphysics online testing device according to claim 1, characterized in that, The inlet and outlet structures of the water and air flow field include step structures or distribution zone channels.

8. The fuel cell multiphysics online testing device according to claim 1, characterized in that, The device also includes peripherals for a data acquisition module (6), a computer (7), a load (8), and an excitation generator (9). The measurement signals from the electrical density impedance measurement board (1) and the multiphysics field measurement board are imported into the data acquisition module (6) and finally uploaded to the computer (7). The load (8) and the excitation generator (9) are connected to both ends of the stack. The computer (7) processes the measurement signals, controls the state of the load (8), and controls the disturbance input of the excitation generator (9). The device also includes peripheral equipment for a signal control switch (5). The signal control switch (5) is located between the main body and the data acquisition module (6) and is controlled by a computer (7). The measurement signals of the electrical density impedance measurement board (1) and the multiphysics field measurement board are imported into the data acquisition module (6) through the signal control switch (5). The computer (7) controls the opening and closing of the signal control switch (5).

9. A method for online testing of fuel cells using multiphysics, characterized in that, The method uses the fuel cell multiphysics online testing device as described in any one of claims 1 to 8 for testing, and the method includes the following steps: The computer (7) corrects the current density signal of the resistor (14) and the temperature signal of the sensor at high temperature to reduce the influence of the heating of the resistor (14) on the current density measurement and the influence of the sensor installation location on the temperature measurement, and obtains the current density and temperature distribution of the reaction zone of the membrane electrode (10). The correction relationship comes from experimental calibration and analytical model calculation. The current density test is performed by computer (7) through finite element calculation to obtain the relationship between the current density flowing through resistor (14) and the actual temperature of resistor (14) under specific battery reaction temperature and cooling water temperature conditions. The relationship between the voltage drop across resistor (14) and the actual resistance value of resistor (14) is further obtained, thereby calculating the current density of resistor (14) in each zone. Temperature test: The computer (7) calculates the relationship between the temperature t0 of the battery membrane electrode (10), the temperature t1 measured by the temperature and humidity sensor (19), and the cooling water temperature t2 through finite element calculation. Based on the temperature t1 measured by the temperature and humidity sensor (19) and the cooling water temperature t2, the temperature t0 of the membrane electrode (10) in each zone is calculated. For the partition impedance test, a sinusoidal micro-interference is applied to each test partition of the fuel cell by an excitation generator (9), and the data acquisition module (6) collects the frequency response signal of each partition in real time. The computer (7) calculates the AC impedance of each partition based on the response signal.

10. The online multiphysics testing method for fuel cells according to claim 9, characterized in that, When the number of acquisition channels is insufficient, the measurement signals in each zone share one acquisition channel. The user controls the opening and closing of the signal control switches (5) of various physical quantities through the computer (7) according to the needs, so as to realize the measurement of a certain physical quantity; or, the opening and closing sequence and alternation frequency of the signal control switches (5) can be adjusted through the computer (7) to realize the sequential measurement of multiple physical fields in different regions of the flow field, and finally complete the entire flow field test, while adjusting the refresh frequency of the distribution image.

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