A method and device for detecting turbulence of a fuel cell plate flow channel

Abstract

The present invention discloses a method and device for detecting the turbulence of a fuel cell plate flow channel, and belongs to the field of fuel cell technology. The detection method comprises the following steps: using a hot wire anemometer to measure the instantaneous voltage of a detection point in the plate flow channel at a certain sampling frequency, wherein the hot wire anemometer comprises a hot wire, the hot wire is placed in the flow channel, and is perpendicular to the flow direction of the airflow in the flow channel; calculating the average voltage according to the instantaneous voltage, the average voltage being the average of the instantaneous voltages within the sampling time; calculating the turbulence according to the following formula: I=V' / V, wherein V' is the instantaneous voltage, V is the average voltage, and I is the turbulence. The present invention proposes a new technical means for detecting the turbulence of a fuel cell plate flow channel. This method utilizes the principle of a hot wire anemometer to convert the flow velocity signal into a voltage signal for measurement, thereby realizing the accurate detection of the turbulence of the flow channel inside the fuel cell plate.

Description

Technical Field

[0001] The invention relates to the technical field of fuel cells, and in particular to a method and a device for detecting turbulence of a fuel cell plate flow channel. Background Art

[0002] In the field of fuel cell technology, the plate, as the core component of fuel cell equipment, undertakes multiple functions such as transmitting reaction gases, conducting electricity, and providing structural support. The design of the flow channel inside the plate directly affects the performance of the fuel cell, so the optimization and evaluation of the plate design is particularly important.

[0003] Although current fuel cell technology has made significant progress, it still faces many challenges in the evaluation of plate design, especially in detecting turbulence in the flow channel. In the past, researchers could only rely on simulation results to make preliminary evaluations of plate design, but the simulation results were often affected by many factors and could not fully reflect the actual situation. Traditional turbulence detection technology is mainly used in large-scale fields such as ocean currents and air flow fields. Its measurement methods and equipment are often not suitable for precision-processed micro-manufactured structures such as fuel cell plates. The design of fuel cell plates requires extremely high precision and a specific flow channel layout to ensure that the reaction gases can be efficiently and evenly distributed and transmitted.

[0004] Due to the lack of an effective turbulence detection method for fuel cell plate design, it is difficult for researchers to quickly and accurately evaluate the performance of different plate designs in terms of enhanced mass transfer and other key performance. This limits the further development and optimization of fuel cell technology. Therefore, developing a turbulence detection method suitable for fuel cell plates is of great significance for evaluating and optimizing plate design. Summary of the invention

[0005] In view of the problem of lack of suitable turbulence detection method for fuel cell plates, the present invention proposes an innovative turbulence detection method and device, which is suitable for measuring the effect of fuel cell plate design on mass transfer enhancement. The method and device utilize the principle of hot wire anemometer to convert the flow velocity signal into a voltage signal for measurement. The hot wire anemometer places a thin metal wire (i.e., hot wire) that is heated by electricity in the airflow, and indirectly measures the flow velocity based on the relationship between the heat dissipation of the hot wire in the airflow and the flow velocity. The change in heat dissipation causes the change in the temperature of the hot wire, which in turn causes the change in resistance, thereby converting the flow velocity signal into a measurable voltage signal.

[0006] The present invention uses a hot wire anemometer to measure the velocity pulsation in the electrode plate flow channel, and then evaluates the turbulence of the electrode plate flow channel. In this way, the performance of the design of the local structure of the electrode plate can be quickly evaluated. In addition, combined with the simulation benchmarking method or the experimental test method, a map of the relationship between turbulence and mass transfer can be obtained, providing a theoretical basis for the optimization of the electrode plate design. In this way, when the electrode plate is subsequently optimized, the turbulence can be directly measured to quantify the effect of the electrode plate design on mass transfer.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] The present invention provides a method for detecting turbulence of a fuel cell plate flow channel, comprising the following steps:

[0009] A hot wire anemometer is used to measure the instantaneous voltage of a detection point in the plate flow channel at a certain sampling frequency, wherein the hot wire anemometer includes a hot wire, which is placed in the flow channel and is perpendicular to the flow direction of the airflow in the flow channel;

[0010] Calculating an average voltage based on the instantaneous voltage, wherein the average voltage is the average of the instantaneous voltage within the sampling time;

[0011] The turbulence is calculated according to the following formula:

[0012]

[0013] in, is the instantaneous voltage, is the average voltage, is the turbulence.

[0014] According to a specific embodiment of the present invention, the sampling frequency is 10-900 kHz.

[0015] According to a specific embodiment of the present invention, the depth of the hot wire inserted into the flow channel is 1 / 2 to 1 / 5 of the total depth of the flow channel.

[0016] The present invention also provides a device for detecting turbulence of a fuel cell plate flow channel, comprising a plate test assembly, a hot wire anemometer, a data acquisition module and a data processing module connected in sequence;

[0017] The plate test assembly is formed by closely combining the test fixture and the plate, the plate includes a flow channel, and the test fixture is sealed and placed on the upper part of the flow channel; the flow channel is designed with an inlet and an outlet, which are used for the inflow and discharge of airflow respectively;

[0018] The hot wire anemometer is used to measure the instantaneous voltage of the detection point in the plate flow channel at a certain sampling frequency; the hot wire anemometer includes a hot wire, which is placed in the flow channel and is perpendicular to the flow direction of the airflow in the flow channel;

[0019] The data acquisition module is used to obtain data generated by the hot wire anemometer;

[0020] The data processing module analyzes and processes the acquired data to calculate the turbulence of the plate flow channel, wherein the calculation formula of the turbulence is as follows:

[0021]

[0022] in, is the instantaneous voltage, is the average voltage, is the turbulence.

[0023] According to a specific implementation of the present invention, the data acquisition module uses a high-performance data acquisition hardware device provided by National Instruments (NI).

[0024] According to a specific embodiment of the present invention, the hot wire anemometer comprises a hot wire probe, and the hot wire probe is an insertion type hot wire probe or a wall type hot wire probe.

[0025] According to a specific embodiment of the present invention, the depth of the hot wire inserted into the flow channel is 1 / 2 to 1 / 5 of the total depth of the flow channel.

[0026] According to a specific embodiment of the present invention, the hot wire probe includes a hot wire, a fork rod, a straight rod and a lead wire.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The present invention proposes a new technical means for detecting the turbulence of the flow channel of the fuel cell plate. This method uses the principle of the hot wire anemometer to convert the flow velocity signal into a voltage signal for measurement, thereby realizing the accurate detection of the turbulence of the flow channel inside the fuel cell plate. The experimental method proposed by the present invention can obtain more accurate and reliable turbulence data when facing complex structures and complex working conditions, providing a more direct and accurate quantitative indicator for the optimization of the plate design, and promoting the further development of fuel cell technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The present invention is a schematic diagram of the structure of a device for detecting turbulence in a fuel cell plate flow channel.

[0030] Figure 2 It is a cross-sectional view of the installation of a hot wire probe and a plate test assembly in one embodiment of the present invention.

[0031] Figure 3 FIG. 1 is a schematic diagram of the installation of a hot wire probe and a plate test assembly in another embodiment of the present invention. DETAILED DESCRIPTION

[0032] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0033] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no substantial technical significance. Any modification of the structure, change in the proportional relationship, or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the effects and purposes that can be achieved by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the present invention. The change or adjustment of their relative relationship should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0034] See also Figure 1 A device for detecting turbulence of a fuel cell plate flow channel includes a plate test assembly 1, a hot wire anemometer 2, a data acquisition module 3 and a data processing module 4 which are connected in sequence.

[0035] The plate test assembly 1 is formed by tightly combining the test fixture and the plate. The two parts fit tightly together to ensure that the airflow can flow between them only through a clear flow channel. The flow channel is designed with clear inlets and outlets for the inflow and discharge of air respectively, thereby effectively guiding and constraining the flow path of the airflow.

[0036] The hot wire anemometer 2 is used to detect the instantaneous voltage inside the flow channel. The hot wire anemometer 2 includes a hot wire, which is placed in the flow channel and perpendicular to the flow direction of the airflow in the flow channel. The hot wire anemometer indirectly measures the flow velocity by placing a thin metal wire (i.e., hot wire) that is electrically heated in the airflow, based on the relationship between the heat dissipated by the hot wire in the airflow and the flow velocity. Changes in heat dissipation lead to changes in the temperature of the hot wire, which in turn causes changes in resistance, thereby converting the flow velocity signal into a measurable voltage signal. This link is the key to measuring turbulence. The hot wire anemometer can sensitively capture tiny changes in flow velocity, providing a reliable basis for subsequent data analysis.

[0037] The hot wire is perpendicular to the flow direction of the airflow, and the velocity component of the fluid in the vertical flow direction can be measured. The direction of this velocity component is the same as the mass transfer direction of the diffusion layer of the plate. The hot wire anemometer includes a hot wire probe. The hot wire probe includes a hot wire. The distance of the hot wire inserted into the flow field should be kept appropriate to avoid the interference of the hot wire on the flow field. Usually, the depth of the hot wire inserted into the flow channel is 1 / 2~1 / 5 of the total depth of the flow channel. By arranging detection points in the reaction area of ​​the fuel cell plate and arranging multiple detection points along the direction from gas inlet to gas outlet, more comprehensive flow field information can be obtained. Analyze the differences in turbulence at different positions to evaluate the comprehensive impact of the plate design on the flow field uniformity and mass transfer efficiency.

[0038] Considering different flow channel structure scales, an inserted hot wire probe or a wall-mounted hot wire probe can be selected. In a specific example, the hot wire probe 21 and the plate test assembly 1 are installed in a cross-sectional view as shown in FIG. Figure 2 As shown. The hot wire probe is an inserted hot wire probe. The hot wire probe 21 includes a hot wire 211, a fork rod 212, a straight rod 213 and a lead 214. The plate test assembly 1 is formed by a test fixture 11 and a plate 12 that are tightly combined. The test fixture 11 is located above the plate 12, and a flow channel 121 is formed on the plate. In this example, the channel groove width W1 is 0.4~0.8mm, so a customized miniature hot wire probe is used to detect the air flow velocity in the flow channel. The customized hot wire probe has the characteristics of high sensitivity and fast response, can accurately measure tiny flow velocity changes, and can measure velocity pulsations in one or two dimensions. Figure 2 The gas flow rate in the X-axis direction is measured.

[0039] In another specific example, the hot wire probe and the plate test assembly 1 are installed as shown in FIG. Figure 3 As shown. The hot wire probe is a wall-type hot wire probe. Identify the area where turbulence occurs obviously in the fuel cell plate, select the detection point near a local structure of the flow channel 121 in the plate 12 designed for enhanced mass transfer, and drill holes around the local structure to install hot wire probes, including 2 hot wire probes in the Z-axis direction and 2 hot wire probes in the X-axis direction. The hot wire 211 of the hot wire probe in the Z-axis direction is parallel to the Z-axis direction of the plate 12 and is in close contact with the upper or lower surface of the flow channel 121. The hot wire 211 of the hot wire probe in the Y-axis direction is parallel to the Y-axis direction of the plate 12 and is in close contact with the side of the flow channel 121. According to the symmetry and asymmetry of the flow, the number of holes is appropriately increased or decreased. Use thermosetting glue or silicone to install, position and seal the straight rod 213 of the hot wire probe and the mounting hole 122.

[0040] In summary, the measurement system achieves accurate measurement of the turbulence of the electrode plate through close cooperation and efficient coordination of various modules. This achievement not only provides strong technical support for research in related fields, but also lays a solid foundation for future applications and development.

[0041] The hot wire anemometer is connected to the data acquisition module 3, and the data acquisition module 3 is connected to the data processing module 4 to record the data generated by the hot wire anemometer 2 in real time and analyze the turbulence data. The data acquisition module 3 is used to obtain the data generated by the hot wire anemometer 2. In a specific example, the module uses high-performance data acquisition hardware equipment provided by National Instruments (NI) to ensure the accuracy and real-time performance of the data. Finally, the data processing module 4 performs in-depth analysis and processing on the acquired data. Through a series of algorithms and models, the module can accurately calculate the turbulence of the flow channel in the plate test assembly.

[0042] Adjust the parameters such as the overheat ratio of the hot wire anemometer. The linear velocity in the flow channel of the fuel cell plate is about 5~20m / s during use. The sampling frequency is 10 to 900 KHz. Collect the instantaneous voltage in the flow channel ( ). Average voltage ( ) corresponds to the average flow velocity ( ), instantaneous voltage ( ) corresponds to the instantaneous flow rate ( ), calculate the turbulence ( ). The average voltage is the average of the instantaneous voltage within the sampling time.

[0043]

[0044] During the experimental test, the flow field is calibrated first: under constant pressure, temperature, and humidity conditions, the turbulence of the flow field of the flow test reference plate structure is adjusted. Then, different structure plates are switched for testing, and the voltage signal at a specific position is collected to compare the turbulence of different plate types. This method does not power the battery or perform load operations during the test, which enables a simple initial turbulence test and allows for more convenient plate structure design.

[0045] The detection method and detection device of the present invention can also be selected as an online measurement method to monitor the turbulence and the voltage and current data of the battery at the same time. During the online measurement, the fuel cell is powered on and loaded, and the total mass transfer resistance is obtained by measuring the limiting current of the fuel cell online. In the offline experiment, the membrane electrode is disassembled to obtain the mass transfer resistance of the flow channel ( ). Experimental method to establish the relationship between turbulence and relation.

[0046] In addition, by combining simulation benchmarking or the above-mentioned online measurement method, a map of the relationship between turbulence and mass transfer can be obtained. In this way, when optimizing the plate design in the future, the effect of the plate design on mass transfer can be quantified by directly measuring the turbulence.

Claims

1. A method for detecting turbulence of a fuel cell plate flow channel, characterized in that: The method uses a detection device for the turbulence of a fuel cell plate flow channel to perform detection, wherein the detection device comprises a plate test assembly, a hot wire anemometer, a data acquisition module and a data processing module connected in sequence; The plate test assembly is formed by closely combining the test fixture and the plate, the plate includes a flow channel, and the test fixture is sealed and placed on the upper part of the flow channel; the flow channel is designed with an inlet and an outlet, which are used for the inflow and discharge of airflow respectively; The hot wire anemometer comprises a hot wire; The data acquisition module is used to obtain data generated by the hot wire anemometer; The data processing module analyzes and processes the acquired data to calculate the turbulence of the electrode plate flow channel; The method for detecting the turbulence of the fuel cell plate flow channel comprises the following steps: A hot wire anemometer is used to measure the instantaneous voltage of a detection point in the plate flow channel at a certain sampling frequency, wherein the hot wire anemometer includes a hot wire, which is placed in the flow channel and is perpendicular to the flow direction of the airflow in the flow channel; Calculating an average voltage based on the instantaneous voltage, wherein the average voltage is the average of the instantaneous voltage within the sampling time; The turbulence is calculated according to the following formula: in, is the instantaneous voltage, is the average voltage, is the turbulence; The hot wire probe is a wall-type hot wire probe; The process of measuring the instantaneous voltage of the detection point in the plate flow channel includes: identifying the area where turbulence occurs obviously in the fuel cell plate, selecting the detection point to be located near a local structure of the flow channel in the plate designed for enhanced mass transfer, drilling holes around the local structure and installing hot wire probes, which are 2 hot wire probes in the Z-axis direction and 2 hot wire probes in the X-axis direction, respectively, the hot wires of the hot wire probes in the Z-axis direction are parallel to the Z-axis direction of the plate and are in close contact with the upper or lower surface of the flow channel, and the hot wires of the hot wire probes in the Y-axis direction are parallel to the Y-axis direction of the plate and are in close contact with the side of the flow channel.

2. The detection method according to claim 1, characterized in that: The sampling frequency is 10-900 kHz.

3. The detection method according to claim 1, characterized in that: The depth of the hot wire inserted into the flow channel is 1 / 2 to 1 / 5 of the total depth of the flow channel.

4. The detection method according to claim 1, characterized in that: The data acquisition module uses high-performance data acquisition hardware equipment provided by National Instruments.

Images