An experimental device and method for testing the pre-compression pressure distribution of a fuel cell stack

Abstract

The application relates to an experimental device and method for testing the pre-tightening pressure distribution of a fuel cell stack, which comprises an experimental table base, a fuel cell lower support, a guide rod, a fuel cell guide rod, an array type flexible pressure sensor module, a secondary pressure tightening module, a primary pressure tightening module, an upper support plate, a stepping motor, a fuel cell stack and a piston control circuit. The primary pressure tightening module is driven by the stepping motor to tighten the secondary pressure tightening module. The secondary pressure tightening module tightens the fuel cell stack through a secondary pressure tightening module support, and simultaneously lowers the fuel cell stack through a floating piston. Array type thin film pressure sensors are used to acquire the contact pressure between the fuel cell stack components in real time. Compared with the prior art, the application avoids the complex experimental process in the design process of the conventional fuel cell assembly scheme, greatly simplifies the experimental process, realizes the experiment on fuel cell stacks of different specifications, and has the advantages of simple operation and effectiveness.

Description

Technical Field

[0001] This invention relates to the field of fuel cell testing, and in particular to an experimental apparatus and method for testing the pre-tightening pressure distribution of a fuel cell stack. Background Technology

[0002] A fuel cell is an energy conversion device that directly converts the chemical energy in fuel into electrical energy. It features high energy conversion efficiency, is green and pollution-free, and operates with low noise. Against the backdrop of increasingly serious environmental pollution and energy depletion, it is considered one of the ideal energy sources for the future.

[0003] To meet the output power requirements of heavy-duty applications such as heavy trucks and locomotives, increasing the effective area of ​​individual cells or increasing the number of cells to improve the single-stack power of fuel cell stacks is one of the future development directions. However, the increasing size of fuel cell stacks will increase the difficulty of assembly, causing uneven in-plane pressure distribution, exacerbating the differences in the distribution of internal electron and gas transport states, and leading to a decrease in fuel cell output performance. This uneven pressure distribution phenomenon is closely related to the pre-compression and tensioning process during assembly. Optimizing the fuel cell stack clamping structure and adjusting the pre-tightening force distribution can effectively alleviate this problem. Therefore, achieving controllable simulation of the pre-compression and tensioning process in fuel cell stack assembly and obtaining the in-plane pressure distribution state is crucial for the structural design and assembly process design of fuel cell stacks.

[0004] Research on fuel cell stack assembly can be divided into two categories: one is to obtain the in-plane stress distribution of the stack through static simulation using numerical methods, and the other is to measure the in-plane pressure distribution of the stack after assembly using methods such as pressure-sensitive paper. The former, limited by computing power, suffers from problems such as long computation time, low accuracy, and complex adjustments when simulating the assembly process of large-scale stacks, resulting in a certain discrepancy with actual conditions. The latter currently lacks a simulation and testing scheme for the entire process, making testing different clamping schemes cumbersome; furthermore, if pressure-sensitive paper testing is used, online quantitative measurement of pressure cannot be achieved, making it difficult to quantitatively control the stack pre-tightening strategy. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art by providing an experimental apparatus and method for testing the pre-tightening pressure distribution of fuel cell stacks, which can obtain real-time pressure distribution parameters, realize batch testing of in-plane distribution of fuel cell stacks, and is easy to operate and flexible to use.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] According to one aspect of the present invention, an experimental apparatus for testing the pre-tightening pressure distribution of a fuel cell stack is provided, comprising a fuel cell stack, a primary clamping module, a secondary clamping module, and an array-type flexible pressure sensor module; the primary clamping module includes a driving plate, the secondary clamping module includes a secondary clamping module support and a floating piston, the driving plate is fixedly connected to the secondary clamping module support, the lower surface of the secondary clamping module support has multiple circular holes forming an oil chamber with the floating piston, the floating piston is multiple in number and presses above the fuel cell stack; the array-type flexible pressure sensor module is located in the fuel cell stack.

[0008] Furthermore, the fuel cell stack includes, from top to bottom, an upper fuel cell end plate, an upper current collector, a bipolar plate, a lower current collector, and a lower fuel cell end plate; the lower surface of the secondary clamping module support is connected to the outer surface of the upper fuel cell end plate, and the outer surface of the upper fuel cell end plate has an installation platform for installing a nut or metal strip at the position corresponding to the floating piston, and the end of the floating piston connected to the nut or metal strip is provided with a metal platform.

[0009] Furthermore, the experimental setup also includes an experimental platform base and a fuel cell lower support. The experimental platform base is provided with mounting points, and the fuel cell lower support is mounted on the experimental platform base through the mounting points. The outer surface of the fuel cell lower end plate has a mounting platform for installing nuts or metal strips at the position corresponding to the floating piston, and the fuel cell lower support has a support platform at the position corresponding to the mounting platform.

[0010] Furthermore, the experimental setup also includes guide rods and fuel cell guide rods. The guide rods connect the experimental platform base and the upper support plate, while the fuel cell guide rods are located outside the lower support of the fuel cell and are used to constrain the lateral movement of the various components of the fuel cell stack. There are multiple guide rods and multiple fuel cell guide rods.

[0011] Furthermore, the drive plate has multiple through holes at its edge, the number of which is the same as the number of guide rods. Metal polymer sliding bearings are installed in the through holes, and the metal polymer sliding bearings cooperate with the guide rods.

[0012] Furthermore, the experimental device also includes an upper support plate and a stepper motor. The stepper motor is mounted on the upper support plate and drives the first-stage pressing module to move longitudinally. The first-stage pressing module also includes a drive column, one end of which is connected to the stepper motor and the other end is fixedly connected to the drive pressure plate.

[0013] Furthermore, the experimental setup also includes a piston control circuit, which connects the two ends of all floating pistons to control their bidirectional movement.

[0014] Furthermore, the piston control circuit controls each floating piston using both synchronous and asynchronous motion control, and can individually regulate and maintain the output pressure. The control of different floating pistons is independent of each other.

[0015] According to another aspect of the present invention, an experimental method for testing the pre-tightening pressure distribution of a fuel cell stack is provided, comprising an experimental preparation stage, a data acquisition stage, and a data processing stage. The data acquisition stage includes the following steps:

[0016] Initiate the fuel cell pressure tightening procedure;

[0017] The stepper motor drives the first-stage and second-stage clamping modules to move downwards, so that the lower surface of the second-stage clamping module contacts the fuel cell stack, simulating the pre-compression stage in the fuel cell stack assembly process;

[0018] The floating piston is controlled to press down the upper plate of the fuel cell in a certain sequence according to the pre-calculated pressure, simulating the tensioning stage in the assembly process of the fuel cell stack.

[0019] During the experiment, the readings of the pressure sensor were read and recorded at a certain sampling rate.

[0020] Furthermore, the steps in the experimental preparation phase include placing the fuel cell stack and array-type flexible pressure sensor module, setting the pressure tightening program, and manually adjusting the primary and secondary pressure modules above the fuel cell stack.

[0021] The data processing phase involves depressurizing the primary and secondary clamping modules to restore them to their initial state, recording the test data, and obtaining test data such as in-plane pressure distribution through data post-processing.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] 1. This invention designs an experimental device for testing the pre-tightening pressure distribution of a fuel cell stack, featuring a two-stage clamping module structure. The first-stage clamping module, driven by a stepper motor, clamps the fuel cell stack to simulate the pre-compression stage during fuel cell stack assembly. Simultaneously, the second-stage clamping module presses the fuel cell stack through its support to simulate the tensioning stage during assembly, while a floating piston presses down on the fuel cell stack. Furthermore, an array of thin-film pressure sensors is used to acquire the contact pressure between fuel cell stack components in real time, avoiding the complex experimental procedures of traditional fuel cell assembly designs and greatly simplifying the experimental process.

[0024] 2. This invention enables experiments on fuel cell stacks of different specifications by utilizing clamping modules and bases of different areas and shapes, and the operation is simple and effective.

[0025] 3. This invention proposes an experimental method to simulate the pre-compression and tensioning process of a fuel cell stack by applying a controllable load, and to realize online measurement of the pressure distribution within the stack, providing a way for experimental research on the pressure distribution of fuel cells. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the overall experimental apparatus of the present invention;

[0027] Figure 2 This is a schematic diagram of the experimental method of the present invention;

[0028] Figure 3 This is a pressure distribution cloud map of the MEA region during experiments conducted according to the present invention.

[0029] In the diagram, 1. Experimental platform base; 2. Fuel cell lower support; 3. Guide rod; 4. Fuel cell guide rod; 5. Array-type flexible pressure sensor module; 6. Secondary clamping module; 61. Secondary clamping module support; 62. Floating piston; 7. Primary clamping module; 72. Drive pressure plate; 71. Drive column; 8. Upper support plate; 9. Stepper motor; 10. Fuel cell stack; 101. Fuel cell upper end plate; 102. Current collector; 103. Bipolar plate; 104. Current collector; 105. Fuel cell lower end plate; 11. Piston control circuit. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0031] The present invention proposes an experimental apparatus for testing the pre-tightening pressure distribution of a fuel cell stack, such as... Figure 1 As shown, it includes an experimental platform base 1, a fuel cell lower support 2, a guide rod 3, a fuel cell guide rod 4, an array-type flexible pressure sensor module 5, a secondary clamping module 6, a primary clamping module 7, an upper support plate 8, a stepper motor 9, a fuel cell stack 10, and a piston control circuit 11.

[0032] The experimental platform base 1 and the upper support plate 8 are connected and fixed together by four guide rods 3, forming the experimental platform frame. The fuel cell lower support 2, guide rods 3, array-type flexible pressure sensor module 5, secondary clamping module 6, and primary clamping module 7 are arranged and installed sequentially from bottom to top on the experimental platform base 1. A stepper motor 9 is located above the upper support plate 8 and is fixedly connected to the primary clamping module 7. The fuel cell guide rod 4 is located outside the fuel cell lower support 2 and is used to restrict the lateral movement of the fuel cell stack 10.

[0033] The fuel cell stack 10 includes, from top to bottom, an upper fuel cell end plate 101, an upper current collector 102, a bipolar plate 103, a lower current collector 104, and a lower fuel cell end plate 105. The lower fuel cell end plate 105 is mounted on the lower fuel cell support 2. The lower surface of the secondary clamping module support 61 is in contact with the outer surface of the upper fuel cell end plate 101. The upper fuel cell end plate 101 and the lower fuel cell end plate 105 have mounting platforms for installing tensioning bolts, nuts, or metal strips. In a preferred embodiment, the mounting platform can be a recess or a boss.

[0034] In this embodiment, the experimental platform base 1 is provided with mounting points, and the fuel cell lower support 2 is mounted on the experimental platform base 1 through the mounting points. In a preferred embodiment, the mounting points are T-slots, and the experimental platform base 1 and the fuel cell lower support 2 are connected and fixed by screws and T-nuts. The fuel cell lower support 2 provides fixation for the fuel cell stack 10 through a support platform, the position of which corresponds to the position of the mounting points on the lower end plate 105 of the fuel cell. In a preferred embodiment, the support platform can be a frustum or a square.

[0035] A stepper motor 9 is mounted on the upper support plate 8 to drive the primary clamping module 7 to move up and down along the guide rod 3, thereby applying and maintaining the primary clamping force of the fuel cell stack 10. The primary clamping module 7 consists of a drive column 71 and a drive pressure plate 72. One end of the drive column 71 is connected to the drive pressure plate 72 via a flange and screws, and the other end is connected to the stepper motor 9. Four circular holes are opened near the two side edges of the drive pressure plate 72, and metal polymer sliding bearings are placed in the holes. The bearings cooperate with the guide rod 3 to reduce the sliding friction between the guide rod 3 and the drive pressure plate 72.

[0036] The secondary clamping module 6 includes a secondary clamping module support 61 and floating pistons 62. The number and position of the floating pistons 62 correspond to the positions of the mounting points on the upper end plate 101 of the fuel cell. A circular hole is formed on the secondary clamping module support 61 at the position corresponding to the floating piston 62, creating an oil chamber. The oil chamber is connected to the piston control circuit 11 via inlet / outlet oil passages and a flexible stainless steel pipe. A metal frustum or square platform is connected to the outside of the floating piston 62, contacting the mounting recess or boss of the nut or metal strip on the upper end plate 101 of the fuel cell. The floating piston 62 is driven to move by controlling the flow rate of hydraulic oil and the oil pressure at both ends of the floating piston 62, simulating the tensioning process of the fuel cell bolts or metal strip.

[0037] In a preferred embodiment, the upper surface of the secondary clamping module support 61 contacts the lower surface of the drive pressure plate 72 and is fixed by screws, while the lower surface contacts the outer surface of the upper end plate 101 of the fuel cell stack, thereby realizing the synchronous movement of the two-stage modules and the transmission of the primary clamping force.

[0038] In this embodiment, the array-type flexible piezoelectric sensor module 5 is placed inside the fuel cell stack 10 to collect the contact pressure distribution between internal components in real time. The placement and number of sensors can be determined according to actual testing requirements, and can be placed between the anode and cathode bipolar plates, between the end plate and the current collector, or between the current collector and the bipolar plates. As a preferred embodiment, the stepper motor and floating piston are driven by a programmable control computer, the array-type flexible piezoelectric sensor data is read and saved, and the system status is visualized and monitored.

[0039] In a preferred embodiment, the array-type flexible piezoelectric sensor module 5 consists of multiple thin-film pressure sensors encapsulated on a flexible circuit board. Pressure sensor data is processed and converted into voltage signals by sampling resistors and operational amplifiers. Data acquisition and power supply are communicated with the host computer via a power strip. The number of thin-film pressure sensors and the area of ​​each sensor are selected based on the area of ​​the MEA region being measured, to match different sized piezoelectric stacks and obtain different spatial resolution test accuracies.

[0040] Specifically, the cross-sectional dimensions of the secondary clamping module support 61 and the lower fuel cell support 2 are the same as the cross-sectional dimensions of the fuel cell stack 10, and the positions of the floating piston 62 and the boss of the lower fuel cell support 2 are the installation positions of the tensioning bolts of the fuel cell stack 10. Therefore, by replacing the secondary clamping module 6 and the lower fuel cell support 2, the purpose of studying fuel cell stacks 10 of different sizes can be achieved.

[0041] Specifically, the device is equipped with a piston control circuit 11 that connects the two ends of all floating pistons 62 to control the bidirectional movement of the floating pistons 62. The control of different pistons in the secondary clamping module 6 should be independent of each other, enabling synchronous or asynchronous movement control of different pistons, and enabling individual regulation and maintenance of output pressure to truly simulate the bolt tensioning sequence and preload magnitude during fuel cell stack assembly.

[0042] Figure 2 The complete experimental procedure was demonstrated, comprising three stages: experimental preparation, data acquisition, and data processing. Experimental preparation mainly involved placing the fuel cell stack 10 and the array-type flexible piezoelectric sensor module 5, setting the clamping program, and manually adjusting the clamping module above the fuel cell stack 10. The second stage began when data recording commenced. After the clamping program was activated, the drive motor moved the clamping module downwards, bringing the lower surface of the secondary clamping module 6 into contact with the end plate of the fuel cell stack 10, and clamping the fuel cell stack 10 with a predetermined primary clamping force F1, simulating the pre-compression stage during the assembly of the fuel cell stack 10. Then, the floating piston 62 was controlled to press down on the fuel cell end plate in a specific sequence according to pre-calculated pressure, simulating the tensioning stage during the assembly of the fuel cell stack 10. During this period, the pressure sensor readings were read and recorded at a certain sampling rate. After the clamping program ended, the third stage of the experiment began. This stage mainly involved depressurizing the clamping module to restore its initial state and recording the test data. Data post-processing was then used to obtain test data such as the in-plane pressure distribution.

[0043] As one embodiment, taking a fuel cell single-cell experimental sample with a cross-sectional area of ​​100mm*100mm (MEA cross-sectional area of ​​50mm*50mm) as an example, it was tightened with 8 bolts, each with a preload torque of 6.0 N·m. Using the test method proposed in this invention, the pressure distribution in the bipolar plate MEA region was obtained, and the results are as follows. Figure 3 As shown.

[0044] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An experimental apparatus for testing the pre-tightening pressure distribution of a fuel cell stack, characterized in that, The system includes a fuel cell stack (10), a primary clamping module (7), a secondary clamping module (6), an array-type flexible pressure sensor module (5), and a stepper motor (9). The primary clamping module (7) includes a drive plate (72), and the secondary clamping module (6) includes a secondary clamping module support (61) and a floating piston (62). The drive plate (72) is fixedly connected to the secondary clamping module support (61). The lower surface of the secondary clamping module support (61) has multiple circular holes that form an oil chamber with the floating piston (62). There are multiple floating pistons (62) that press against the fuel cell stack (10). The array-type flexible pressure sensor module (5) is located in the fuel cell stack (10). The first-level pressing module (7) is driven by a stepper motor (9) to press the second-level pressing module (6); while the second-level pressing module (6) presses the fuel cell stack through the second-level pressing module support (61) to simulate the pre-pressing stage in the assembly process of the fuel cell stack, it also presses down the fuel cell stack through a floating piston (62) to simulate the tensioning stage in the assembly process of the fuel cell stack.

2. The experimental apparatus for testing the pre-tightening pressure distribution of a fuel cell stack according to claim 1, characterized in that, The fuel cell stack (10) includes, from top to bottom, an upper fuel cell end plate (101), an upper current collector (102), a bipolar plate (103), a lower current collector (104), and a lower fuel cell end plate (105); the lower surface of the secondary clamping module support (61) is connected to the outer surface of the upper fuel cell end plate (101), and the outer surface of the upper fuel cell end plate (101) has an installation platform for installing nuts or metal strips at the position corresponding to the floating piston (62), and the end of the floating piston (62) connected to the nut or metal strip is provided with a metal platform.

3. The experimental apparatus for testing the pre-tightening pressure distribution of a fuel cell stack according to claim 2, characterized in that, The experimental device also includes an experimental platform base (1) and a fuel cell lower support (2). The experimental platform base (1) is provided with mounting points, and the fuel cell lower support (2) is installed on the experimental platform base (1) through the mounting points. The outer surface of the fuel cell lower end plate (105) has an installation platform for installing nuts or metal strips at the position corresponding to the floating piston (62), and the fuel cell lower support (2) has a support platform at the position corresponding to the installation platform.

4. The experimental apparatus for testing the pre-tightening pressure distribution of a fuel cell stack according to claim 3, characterized in that, The experimental device also includes a guide rod (3) and a fuel cell guide rod (4). The guide rod (3) connects the experimental platform base (1) and the upper support plate (8). The fuel cell guide rod (4) is located outside the lower support (2) of the fuel cell and is used to constrain the lateral movement of each component of the fuel cell stack (10). There are multiple guide rods (3) and multiple fuel cell guide rods (4).

5. The experimental apparatus for testing the pre-tightening pressure distribution of a fuel cell stack according to claim 4, characterized in that, The driving pressure plate (72) has multiple through holes at its edge. The number of through holes is the same as the number of guide rods (3). Metal polymer sliding bearings are installed in the through holes, and the metal polymer sliding bearings cooperate with the guide rods (3).

6. The experimental apparatus for testing the pre-tightening pressure distribution of a fuel cell stack according to claim 1, characterized in that, The experimental device also includes an upper support plate (8), the stepper motor (9) is mounted on the upper support plate (8) and drives the first-stage pressing module (7) to move longitudinally; the first-stage pressing module (7) also includes a drive column (71), one end of the drive column (71) is connected to the stepper motor (9), and the other end is fixedly connected to the drive pressure plate (72).

7. The experimental apparatus for testing the pre-tightening pressure distribution of a fuel cell stack according to claim 6, characterized in that, The experimental apparatus also includes a piston control circuit (11), which connects the two ends of all floating pistons (62) and is used to control the bidirectional movement of the floating pistons (62).

8. The experimental apparatus for testing the pre-tightening pressure distribution of a fuel cell stack according to claim 7, characterized in that, The piston control circuit (11) controls each floating piston (62) in a synchronous motion control and asynchronous motion control manner, and can realize the individual regulation and maintenance of output pressure. The control between different floating pistons (62) is independent of each other.

9. An experimental method for testing the pre-tightening pressure distribution of a fuel cell stack using the experimental apparatus described in any one of claims 1-8, comprising an experimental preparation stage, a data acquisition stage, and a data processing stage, characterized in that, The data acquisition phase includes the following steps: Initiate the fuel cell pressure tightening procedure; The stepper motor (9) drives the first-stage pressing module (7) and the second-stage pressing module (6) to move downwards, so that the lower surface of the second-stage pressing module (6) contacts the fuel cell stack (10), simulating the pre-pressing stage in the assembly process of the fuel cell stack (10); Control the floating piston (62) to press down the upper end plate (101) of the fuel cell in a certain order according to the pre-calculated pressure, simulating the tensioning stage during the assembly of the fuel cell stack (10); During the experiment, the readings of the pressure sensor were read and recorded at a certain sampling rate.

10. The experimental method according to claim 9, characterized in that, The steps of the experimental preparation stage include placing the fuel cell stack (10) and array flexible pressure sensor module (5), setting the pressure tightening program, and manually adjusting the primary pressure module (7) and secondary pressure module (6) above the fuel cell stack (10); The data processing stage involves depressurizing the first-level pressing module (7) and the second-level pressing module (6) to restore them to their initial state, recording the test data, and obtaining the in-plane pressure distribution through data post-processing.

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