Proton exchange membrane fuel cell runner and proton exchange membrane fuel cell

Abstract

The invention provides a proton exchange membrane fuel cell flow channel and a proton exchange membrane fuel cell, the proton exchange membrane fuel cell flow channel comprises a cathode flow channel and an anode flow channel arranged on a bipolar plate, the cathode flow channel is a variable-period three-dimensional wave-shaped flow channel, and / or the anode flow channel is a variable-period three-dimensional wave-shaped flow channel, and / or the cathode flow channel is a variable-period three-dimensional wave-shaped flow channel. And the period of the outlet section of the variable-period three-dimensional wave-shaped flow channel is smaller than that of the inlet section of the variable-period three-dimensional wave-shaped flow channel. By adopting the technical scheme, the cathode flow channel and / or the anode flow channel are / is designed into the variable-period three-dimensional wave-shaped flow channel, and the period of the outlet section of the variable-period three-dimensional wave-shaped flow channel is set to be smaller than that of the inlet section of the variable-period three-dimensional wave-shaped flow channel; the diffusion speed in the direction of an oxygen catalyst layer can be increased, so that oxygen distribution is more uniform, electrochemical reaction is more sufficient, and the performance of the battery is improved.

Description

Technical Field

[0001] The present disclosure relates to the field of fuel cells, and in particular to a proton exchange membrane fuel cell flow channel and a proton exchange membrane fuel cell. Background Art

[0002] In recent years, with the continuous depletion of fossil fuels, renewable energy has garnered widespread attention, with hydrogen in particular emerging as the optimal choice for a greener and cleaner energy mix. Proton exchange membrane fuel cells (PEMFCs), as highly efficient hydrogen energy conversion and utilization devices, consist of bipolar plates that account for over 60% of the cell's mass. These plates transport reactant gases, remove product water and heat, collect current, and support the electrodes. Therefore, a rational bipolar plate flow channel design can not only reduce costs but also promote uniform reactant gas transport, improve water and heat management, and ultimately enhance cell performance.

[0003] However, in related technologies, the bipolar plate flow channel usually adopts a straight flow channel design. This structure affects the diffusion rate of oxygen in the direction of the catalyst layer, the uniformity of oxygen distribution and the efficiency of the electrochemical reaction, thereby affecting the performance of the proton exchange membrane fuel cell. Summary of the Invention

[0004] In order to solve the above technical problems, the embodiments of the present disclosure provide a proton exchange membrane fuel cell flow channel and a proton exchange membrane fuel cell.

[0005] In a first aspect, the present disclosure provides a proton exchange membrane fuel cell flow channel, comprising a cathode flow channel and an anode flow channel disposed on a bipolar plate;

[0006] The cathode flow channel is a variable period three-dimensional wavy flow channel;

[0007] And / or, the anode flow channel is the variable period three-dimensional wavy flow channel;

[0008] The period of the outlet section of the variable-period three-dimensional wavy flow channel is smaller than the period of the inlet section of the variable-period three-dimensional wavy flow channel.

[0009] In a second aspect, the present disclosure further provides a proton exchange membrane fuel cell, comprising an anode flow channel and a cathode flow channel, wherein the anode flow channel and the cathode flow channel adopt the above-mentioned proton exchange membrane fuel cell flow channel.

[0010] The technical solution provided by the embodiments of the present disclosure has at least the following advantages compared with the prior art:

[0011] The disclosed embodiments provide a proton exchange membrane fuel cell flow channel, including a cathode flow channel and an anode flow channel disposed on a bipolar plate, wherein the cathode flow channel is a variable-period three-dimensional wavy flow channel, and / or the anode flow channel is a variable-period three-dimensional wavy flow channel, wherein the period of the outlet section of the variable-period three-dimensional wavy flow channel is less than the period of the inlet section of the variable-period three-dimensional wavy flow channel. A variable-period three-dimensional wavy flow channel is designed to address the problems existing in direct current channels, to explore the effects of the variable-period three-dimensional wavy flow channel on battery output performance, temperature, oxygen distribution, current density, liquid water distribution, and to reveal the fundamental principle by which the variable-period three-dimensional wavy flow channel structure improves mass transfer.

[0012] The results show that with the increase of the depth of the variable period three-dimensional wavy flow channel, the current density and power density of the proton exchange membrane fuel cell continue to increase. In particular, when the depth of the variable period three-dimensional wavy flow channel is 1.2 mm, the battery performance is significantly improved, and its maximum power density is 6942.40 W / m 2 , relative direct current 6159.49W / m 2 It increased by 12.711%. The variable-period three-dimensional wavy flow channel can significantly increase the diffusion rate in the direction of the oxygen catalytic layer. Due to the forced convection effect caused by the variable cross-section, the oxygen concentration gradient between the lower part of the flow channel and the ridge is smaller, indicating that the distribution of oxygen is more uniform. Moreover, it is more obvious that due to insufficient oxygen supply near the outlet section of the flow channel, the oxygen concentration in the outlet section is lower. However, in the variable-period three-dimensional wavy flow channel, the oxygen concentration is higher than that in the straight channel due to the faster change of the wave period in the outlet section. It can also be clearly found that in the variable-period three-dimensional wavy flow channel, the speed of hydrogen in both the inlet and outlet sections is lower than that in the straight channel, indicating that the electrochemical reaction in the variable-period three-dimensional wavy flow channel is more complete. The reaction in the variable-period three-dimensional wavy flow channel is more uniform, the oxygen diffuses more evenly, and the generated water will take away most of the heat. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0014] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0015] Figure 1 A schematic diagram of a three-dimensional model of a proton exchange membrane fuel cell provided in an embodiment of the present disclosure;

[0016] Figure 2A schematic diagram comparing the cross-sectional structures of a straight flow channel and a variable-period three-dimensional wavy flow channel provided in an embodiment of the present disclosure;

[0017] Figure 3 A schematic diagram of a geometric model of wave depth change in a variable-period three-dimensional wavy flow channel provided by an embodiment of the present disclosure;

[0018] Figure 4 A schematic diagram of a cross-sectional structure of a variable-period three-dimensional wavy flow channel provided in an embodiment of the present disclosure;

[0019] Figure 5 Schematic diagram of polarization curves of five flow channels under a basic working condition of 343.15K and 101325Pa provided in an embodiment of the present disclosure;

[0020] Figure 6 A schematic diagram of power density curves of five flow channels under a basic working condition of 343.15K and 101325Pa provided in an embodiment of the present disclosure;

[0021] Figure 7 Schematic diagram of polarization curves of five flow channels under low-temperature conditions of 333.15K and 101325Pa provided in an embodiment of the present disclosure;

[0022] Figure 8 A schematic diagram of power density curves of five flow channels under a low-temperature working condition of 333.15K and 101325Pa provided in an embodiment of the present disclosure;

[0023] Figure 9 Schematic diagram of polarization curves of five flow channels under high pressure conditions of 343.15K and 202650Pa provided in an embodiment of the present disclosure;

[0024] Figure 10 A schematic diagram of power density curves of five flow channels under a high-pressure working condition of 343.15K and 202650Pa provided in an embodiment of the present disclosure;

[0025] Figure 11 Cloud diagrams of oxygen radial diffusion velocities in five flow channels under a basic working condition provided by an embodiment of the present disclosure;

[0026] Figure 12 A schematic diagram of the parasitic power of five flow channel structures and the mass fraction of water at the interface between the catalyst layer, membrane, and diffusion layer provided in an embodiment of the present disclosure;

[0027] Figure 13 A schematic diagram of the molar concentration of oxygen at the catalyst layer of five flow channel structures provided in an embodiment of the present disclosure;

[0028] Figure 14A cloud diagram of oxygen molar concentration distribution at the cathode diffusion layer interface provided by an embodiment of the present disclosure;

[0029] Figure 15 A cloud diagram of the water molar concentration distribution at the interface between the cathode diffusion layer and the catalytic layer provided in an embodiment of the present disclosure;

[0030] Figure 16 A temperature distribution cloud diagram of the interface between the cathode diffusion layer and the catalytic layer provided in an embodiment of the present disclosure;

[0031] Figure 17 A cloud diagram of the anode hydrogen consumption rate along the flow direction provided in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0032] In order to more clearly understand the above-mentioned objectives, features and advantages of the present disclosure, the scheme of the present disclosure will be further described below. It should be noted that the embodiments of the present disclosure and the features therein can be combined with each other in the absence of conflict.

[0033] In the following description, many specific details are set forth to facilitate a full understanding of the present disclosure, but the present disclosure may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present disclosure, rather than all of the embodiments.

[0034] Hydrogen energy, due to its vast reserves, widespread availability, high energy density, high calorific value, clean and pollution-free operation, and safe and easy storage and transportation, is considered the best option for addressing current carbon emissions and achieving a greener and cleaner energy mix. As a highly efficient hydrogen energy conversion and utilization device, PEMFC (Proton Exchange Membrane Fuel Cell) converts chemical energy directly into electrical energy through an electrochemical reaction. Compared to traditional energy conversion devices (such as internal combustion engines), it offers higher energy efficiency and boasts advantages such as high specific power, high power per unit area, fast startup time, suitable operating conditions, and low environmental pollution. It holds broad application prospects in transportation, portable power supplies, and combined heat and power generation. However, key challenges in PEMFC applications remain in improving its performance, durability, and production cost. A PEMFC consists of bipolar plates (BPs), a diffusion layer (GDL), a catalyst layer (CL), and a proton exchange membrane (PEM). The BPs account for over 60% of the cell's mass and over 30% of its cost. They transport reactant gases, remove product water and heat, collect current, and support the electrodes. Therefore, a reasonable bipolar plate flow channel design can reduce costs, promote uniform transport of reaction gases, and hydrothermal management, thereby improving battery performance.

[0035] Uneven distribution of reaction gases will lead to a reduction in the effective reaction area, resulting in low local current density and affecting battery performance. Insufficient water inside the battery will cause the proton exchange membrane to dry out and reduce proton conductivity, while excessive water will cause flooding, affecting gas mass transfer. Excessive water on the flow channel surface will also cause corrosion of the bipolar plates, especially the cathode flow channel. In response to the problems existing in the direct current channel, this paper designs a variable period three-dimensional wavy flow channel to explore the effects of the variable period three-dimensional wavy flow channel on battery output performance, temperature, oxygen distribution, current density, liquid water distribution, etc., and reveals the basic principle of the variable period three-dimensional wavy flow channel structure to improve mass transfer.

[0036] To this end, the disclosed embodiment provides a proton exchange membrane fuel cell flow channel, including a cathode flow channel and an anode flow channel disposed on a bipolar plate, wherein the cathode flow channel is a variable period three-dimensional wavy flow channel, and / or the anode flow channel is a variable period three-dimensional wavy flow channel, wherein the period of the outlet section of the variable period three-dimensional wavy flow channel is less than the period of the inlet section of the variable period three-dimensional wavy flow channel. By adopting this technical solution, the cathode flow channel and / or the anode flow channel are designed as variable period three-dimensional wavy flow channels, and the period of the outlet section of the variable period three-dimensional wavy flow channel is set to be less than the period of the inlet section of the variable period three-dimensional wavy flow channel, which can increase the diffusion rate in the direction of the oxygen catalyst layer, make the distribution of oxygen more uniform, and make the electrochemical reaction more sufficient, thereby improving the performance of the battery.

[0037] Based on this, an embodiment of the present disclosure provides a proton exchange membrane fuel cell flow channel, including a cathode flow channel and an anode flow channel arranged on a bipolar plate, the cathode flow channel is a variable period three-dimensional wavy flow channel and / or the anode flow channel is a variable period three-dimensional wavy flow channel, and the period of the outlet section of the variable period three-dimensional wavy flow channel is smaller than the period of the inlet section of the variable period three-dimensional wavy flow channel.

[0038] Among them, the proton exchange membrane fuel cell channel refers to the flow channel structure processed on the bipolar plate, which is used to guide the reaction gas (such as hydrogen and air) to be evenly distributed to the electrode surface, while discharging the generated water and heat. It is the core functional unit of mass transfer, reaction and thermal management.

[0039] Bipolar plates refer to key components that are conductive, used to separate single cells, distribute reaction gases (hydrogen / air), conduct current, and assist in thermal management. The cathode flow channel refers to the gas flow channel on the cathode side of the bipolar plate, which is used to transport air (oxygen) and discharge the generated water, while promoting the diffusion of oxygen to the cathode catalyst layer. The anode flow channel refers to the gas flow channel on the anode side of the bipolar plate, which is used to transport hydrogen and discharge unreacted residual gas to ensure that hydrogen effectively diffuses to the anode catalyst layer. A variable-period three-dimensional wavy flow channel refers to a structural design in which the geometric parameters of the flow channel (such as wavelength, amplitude, etc.) change in a specific way along the flow direction, forming an undulating wave.

[0040] In the embodiment of the present disclosure, the period of the outlet section of the variable-period three-dimensional wavy flow channel is set to be smaller than the period of the inlet section of the variable-period three-dimensional wavy flow channel, that is, the wave period of the outlet section changes faster, making the oxygen distribution more uniform and the electrochemical reaction more uniform.

[0041] In an optional embodiment, the period of the variable-period three-dimensional wavy flow channel gradually decreases from the inlet to the outlet based on a piecewise function.

[0042] Among them, piecewise function refers to a function defined using different expressions in different intervals.

[0043] In the embodiment of the present disclosure, the variable period three-dimensional wavy flow channel is first divided into multiple intervals, and a periodic function is defined in each interval so that the period gradually decreases in each interval. In addition, the continuity of the period value can be ensured at the junction of each interval, thereby achieving a uniform decrease in the period of the variable period three-dimensional wavy flow channel from the inlet to the outlet.

[0044] In another optional embodiment, the period of the variable-period three-dimensional wavy flow channel gradually decreases from the inlet to the outlet based on an interpolation method.

[0045] Among them, interpolation is a method used to estimate unknown values ​​between known data points.

[0046] In the embodiment of the present disclosure, the period values ​​are first determined at the inlet and outlet of the variable period three-dimensional wavy flow channel, and some key positions are selected in the length direction of the variable period three-dimensional wavy flow channel. The key positions can be evenly distributed or selected according to the variable period three-dimensional wavy flow channel. Then, a period is assigned to each key position to form a sequence of period values, and then the interpolation method is used to estimate the period values ​​between the key points so that the period of the variable period three-dimensional wavy flow channel gradually decreases from the inlet to the outlet.

[0047] In the embodiment of the present disclosure, only the cathode flow channel of the bipolar plate can be set as a variable period three-dimensional wavy flow channel, only the anode flow channel of the bipolar plate can be set as a variable period three-dimensional wavy flow channel, or both the cathode flow channel and the anode flow channel of the bipolar plate can be set as variable period three-dimensional wavy flow channels.

[0048] For ease of understanding, the following is a specific introduction using the example of the cathode flow channel of the bipolar plate being set as a variable-period three-dimensional wavy flow channel.

[0049] like Figure 1 As shown, Figure 1This is a schematic diagram of a three-dimensional model of a proton exchange membrane fuel cell provided in an embodiment of the present disclosure. The proton exchange membrane fuel cell consists of nine parts, with the proton exchange membrane as the center, divided into a cathode and an anode. Correspondingly, the cathode is provided with a cathode current collector, a cathode flow channel, a cathode diffusion layer, and a cathode catalyst layer, and the anode is provided with an anode current collector, an anode flow channel, an anode diffusion layer, and an anode catalyst layer. The cathode flow channel of the bipolar plate is set as a variable period three-dimensional wavy flow channel, which is composed of Figure 1 It can be seen that the flow channel cross section of the variable period three-dimensional wavy flow channel changes periodically from the inlet to the outlet, which is different from the traditional straight flow channel.

[0050] In an optional embodiment, the shape of the variable-period three-dimensional wavy flow channel is generated by a cosine function. The cosine function is y = bcos((0.01πx + a)x) + c, where x is the flow channel length, y is the height of any point on the variable-period three-dimensional wavy flow channel, and a, b, and c are constants.

[0051] Specifically, the value of a is used to adjust the period of the variable-period three-dimensional wavy flow channel, and the values ​​of b and c are used to adjust the depth of the variable-period three-dimensional wavy flow channel.

[0052] like Figure 2 As shown, Figure 2 A schematic diagram comparing the cross-sectional structures of a straight flow channel and a variable period three-dimensional wavy flow channel provided in an embodiment of the present disclosure is shown in FIG. Figure 2 As shown in (b), (c), (d), and (e), the variable period three-dimensional wavy flow channel is generated by the cosine function. By changing the values ​​of b and c, the change of the wave depth Hi of the variable period three-dimensional wavy flow channel is controlled as shown in Figure 3 As shown, Figure 3 A schematic diagram of a geometric model of wave depth change of a variable period three-dimensional wavy flow channel provided by an embodiment of the present disclosure, wherein H i Indicates wave depth, N j The period is represented by changing the value of a to change the period of the wave. The wavelength of the variable period three-dimensional wavy flow channel decreases continuously from the inlet to the outlet. Due to the different values ​​of a, the number of waves N in the variable period three-dimensional wavy flow channel is also different. Figure 4 As shown, Figure 4 A schematic diagram of the cross-sectional structure of a variable period three-dimensional wavy flow channel provided in an embodiment of the present disclosure. Specific parameters are shown in Table 1. Table 1 is a table of PEMFC geometric parameters of different variable period three-dimensional wavy flow channels, which shows the PEMFC geometric parameters of different variable period three-dimensional wavy flow channels.

[0053]

[0054] Table 1

[0055] In order to improve the performance of the proton exchange membrane fuel cell, in an optional embodiment, the depth of the variable-period three-dimensional wavy flow channel can be set to 1.2 mm.

[0056] The depth of the variable-period three-dimensional wavy flow channel refers to the vertical distance from the trough to the peak in the flow channel cross section.

[0057] In the embodiment of the present disclosure, the depth of the variable-period three-dimensional wavy flow channel can be 1.2 mm, which can further improve the performance of the proton exchange membrane fuel cell.

[0058] Specifically, in order to explore the effect of the depth of the periodic three-dimensional wavy flow channel on battery performance, numerical calculations were performed to obtain the performance curves of five flow channels under basic working conditions, four of which are variable-period three-dimensional wavy flow channels and one is a straight flow channel. Figure 5 Schematic diagram of polarization curves of five flow channels under a basic working condition of 343.15K and 101325Pa provided in an embodiment of the present disclosure. Figure 6 This is a schematic diagram of the power density curves of five flow channels under a basic working condition of 343.15K and 101325Pa provided in the embodiment of the present disclosure. Figure 5 The polarization curve (voltage-current density) or Figure 6 The power density curve clearly shows that the PEMFC with a variable-period three-dimensional wavy flow channel performs better. It can also be seen that when the operating voltage is less than 0.6V, that is, when the current density is low, the current density of the flow channels with different structures is not much different. As the operating voltage decreases, the current density continues to increase, and the difference between the current density of the variable-period three-dimensional wavy flow channel and the direct current channel continues to grow. The corresponding power density change trend is also the same. The power density of the variable-period three-dimensional wavy flow channel reaches its maximum at an operating voltage of 0.4V. Due to concentration polarization, the current density approaches the limiting current density. When the operating voltage drops to 0.3V, the current density increase slows down. Therefore, the power density begins to decline as the current density further increases.

[0059] In addition, it can be found that with the increase of the depth of the variable period three-dimensional wavy flow channel, the current density and power density of PEMFC continue to increase. Especially when the depth of the variable period three-dimensional wavy flow channel is d=1.2mm, the battery performance is significantly improved, and its maximum power density is 6942.40W / m 2 , relative to 6891.72W / m for d=1.0mm 2 Increased by 0.735%, relative to the direct current 6159.49W / m 2 An increase of 12.711%.

[0060] In order to explore the effect of operating temperature on the performance of exchange membrane fuel cells, refer to Figure 7 and Figure 8 ,in, Figure 7 Schematic diagram of polarization curves of five flow channels under low temperature conditions of 333.15K and 101325Pa provided in an embodiment of the present disclosure. Figure 8 A schematic diagram of power density curves of five flow channels under low-temperature conditions of 333.15K and 101325Pa provided in an embodiment of the present disclosure.

[0061] Specifically, when the PEMFC operating temperature is 333.15K, the flow channel performance curve follows the same variation pattern as the base operating condition, and as the depth of the variable-period three-dimensional wavy flow channel increases, the battery performance improves. However, it is obvious that as the operating temperature decreases, the current density and power density decrease accordingly. The maximum power density is 6386.64W / m at d = 1.2mm. 2 6942.40W / m relative to 343.15K 2 A decrease of 8.005%.

[0062] In order to explore the effect of working pressure on the performance of exchange membrane fuel cells, refer to Figure 9 and Figure 10 ,in, Figure 9 Schematic diagram of polarization curves of five flow channels under high pressure conditions of 343.15K and 202650Pa provided in an embodiment of the present disclosure. Figure 10 This is a schematic diagram of the power density curves of five flow channels under a high pressure working condition of 343.15K and 202650Pa provided in the embodiment of the present disclosure. Figure 9 、 Figure 10 As shown in Figure 2, by changing the working pressure to 202650Pa, it can be found that the current density and power density are significantly improved, as shown in Figure 2. Figure 9 As shown in the figure, the flow channel performance curve has the same variation pattern as the basic working condition. As the depth of the variable period three-dimensional wavy flow channel increases, the battery performance is better. The maximum power density is 7186.61W / m at d = 1.2mm. 2 Compared with the working pressure of 101325Pa, the 6942.40W / m 2 An increase of 3.518%.

[0063] In an optional embodiment, the length of the inlet section of the variable-period three-dimensional wavy flow channel is 3.0 mm, and the length of the outlet section of the variable-period three-dimensional wavy flow channel is 1.5 mm.

[0064] Among them, the inlet section length of the variable period three-dimensional wavy flow channel refers to the horizontal projection distance from the wave crest to the wave trough at the inlet, and the inlet section length of the variable period three-dimensional wavy flow channel refers to the horizontal projection distance from the wave crest to the wave trough at the outlet.

[0065] For example, Figure 11 Take Case 1 as an example, Figure 11This is a cloud diagram of the oxygen radial diffusion velocity of five flow channels under a basic working condition provided in an embodiment of the present disclosure. In Case 1, the inlet section length La1 is 7.3 mm, and the outlet section length La2 is 2.7 mm.

[0066] In the embodiment of the present disclosure, the inlet section length of the variable period three-dimensional wavy flow channel is set to 3.0 mm, and the outlet section length of the variable period three-dimensional wavy flow channel is set to 1.5 mm, which can further improve the performance of the proton exchange membrane fuel cell.

[0067] In order to further explore the effect of variable period three-dimensional wavy flow channel on oxygen diffusion rate, Figure 11 As shown, it can be seen that the variable-period three-dimensional wavy flow channel can significantly increase the diffusion rate of oxygen toward the catalyst layer. The variable-period three-dimensional wavy flow channel generates forced convection during the flow of oxygen, causing more oxygen to flow toward the diffusion layer. Due to the reduction in the flow channel cross-sectional area, the radial velocity increases. During the cross-sectional change process, a velocity difference is formed, resulting in a pressure difference between the reactant gas inlet and outlet, and between the flow channel and the diffusion layer, promoting oxygen diffusion. In Case 1, due to the slow change in the flow channel period, the oxygen flow direction remains almost unchanged in the longer part of the flow channel inlet, and the radial velocity is low. As the period decreases, the velocity first increases and then decreases. Comparing the four flow channel structures from Cases 1 to 4, it can be found that as the wave period of the variable-period three-dimensional wavy flow channel accelerates, the radial velocity increases, and the change in the velocity gradient continuously decreases. The velocity channel distribution of Cases 2 and 3 is basically the same, and Case 3 has more areas of higher velocity than Case 2. As the period change accelerates further, the inlet section La4=1.9mm and the outlet section Lb4=1.1mm are very close, the overall period becomes smaller, the velocity gradient changes less, and the flow resistance is larger.

[0068] In summary, the variable-period three-dimensional wavy flow channel is beneficial to promoting the radial diffusion movement of oxygen. However, when the period of the inlet section is close to that of the outlet section, the flow loss and parasitic power will increase. When the inlet gas mass flow rate is constant, the performance of the battery will be relatively poor. The structure of Case 3 (La3=3.0mm, Lb3=1.5mm) is relatively better.

[0069] In order to explore the effect of variable period three-dimensional wavy flow channel on water mass fraction and oxygen concentration, as the flow channel structure changes from a straight channel to a variable period three-dimensional wavy flow channel, the parasitic power required is as follows: Figure 12 Shown to be increasing, Figure 12This is a schematic diagram showing the parasitic power of five flow channel structures provided in an embodiment of the present disclosure, and the mass fraction of water at the interface between the catalyst layer, membrane, and diffusion layer. The electrochemical reaction of the PEMFC mainly occurs in the catalyst layer, and a reduction reaction occurs on the cathode side to generate water. The mass fraction of water at the interface between the catalyst layer and the membrane is relatively high. Since the direct flow channel has a smaller perturbation effect on oxygen, the molar concentration of oxygen at the catalyst layer is relatively low, as shown in Figure 13. Figure 13 A schematic diagram of the oxygen molar concentration at the catalytic layer of five flow channel structures provided in an embodiment of the present disclosure. The mass fraction of water is relatively high in the diffusion layer, while the mass fraction of water in the variable period three-dimensional wavy flow channel is significantly reduced, and the molar concentration of the catalytic layer continues to increase. In case 3 (La3=3.0mm, Lb3=1.5mm), the flow channel structure has relatively small parasitic power in the variable period three-dimensional wavy flow channel, and the oxygen concentration and water mass fraction are optimal.

[0070] In order to explore the effect of variable period three-dimensional wavy flow channel on the distribution of water and oxygen, under the basic working condition of working voltage of 0.4V, as shown in the figure: Figure 14 As shown, Figure 14 A cloud diagram of the molar concentration distribution of oxygen at the cathode diffusion layer interface provided in an embodiment of the present disclosure shows that the molar concentration of oxygen in the straight channel and the variable period three-dimensional wavy channel continuously decreases along the flow direction from the inlet to the outlet. Since oxygen enters the battery through the channel and then diffuses through the diffusion layer to the surface of the catalytic layer to undergo an electrochemical reaction, the oxygen concentration below the channel in the two channels is significantly higher than that below the channel ridge. The variable period three-dimensional wavy channel obtains a forced convection effect due to the variable cross-section, and the oxygen concentration change gradient between the lower part of the channel and the ridge is smaller, indicating that the distribution of oxygen is more uniform. Moreover, it is more obvious that due to insufficient oxygen supply near the outlet section of the channel, the oxygen concentration at the outlet section is lower, while the variable period three-dimensional wavy channel has a higher oxygen concentration than the straight channel due to the faster change of the wave period at the outlet section.

[0071] Oxygen will combine with H+ in the PEMFC cathode catalyst layer to generate water. Figure 15 As shown, Figure 15A cloud diagram of the molar concentration distribution of water at the interface between the cathode diffusion layer and the catalytic layer provided in an embodiment of the present disclosure shows that due to the high oxygen concentration near the inlet section of the battery, the corresponding electrochemical reaction will be more intense, and the amount of water generated will increase. However, due to the large oxygen flow rate in the inlet section, the generated water will gather towards the middle and outlet sections of the flow channel. Therefore, at the interface between the two flow channel diffusion layers and the catalytic layer, the molar concentration of water near the inlet section will be significantly lower than that of the outlet section. Moreover, the molar concentration distribution of water below the flow channel and below the ridge also shows the same pattern as the oxygen concentration distribution, with more water generated below the flow channel. At the same time, as the flow channel changes periodically, the generated water gathers more towards the outlet section, which is more conducive to the discharge of liquid water and thus more conducive to the occurrence of flooding. Moreover, the gradient of the change in the molar concentration of water in the inlet and outlet sections is smaller, indicating that the electrochemical reaction is more uniform.

[0072] In order to explore the effect of the variable period three-dimensional wavy flow channel on the internal temperature of the battery, the electrochemical reaction inside the PEMFC will generate a lot of heat. If the heat is not discharged in time, it will lead to uneven temperature distribution inside the battery, especially the performance of the proton exchange membrane, affecting the reaction and battery life. Figure 16 As shown, Figure 16 A temperature distribution cloud diagram of the interface between the cathode diffusion layer and the catalytic layer provided in an embodiment of the present disclosure. Figure 16 Selecting the interface between the catalyst layer and the membrane, we first clearly see that in the straight channel, the temperature gradient on the membrane is large, varying from 347.0K to 351.21K. In the corresponding variable-period three-dimensional wavy channel, the temperature range is 344.05K to 345.70K, with a smaller temperature gradient, indicating a more uniform reaction in the variable-period three-dimensional wavy channel. Oxygen diffusion is more uniform in the variable-period three-dimensional wavy channel, and the generated water dissipates most of the heat, while the straight channel has poor drainage. It can also be seen that the heat distribution is consistent with the patterns of oxygen diffusion, water distribution, and current density.

[0073] In order to explore the effect of the variable period three-dimensional wavy flow channel on the hydrogen velocity, the variable period three-dimensional wavy flow channel increases the cathode oxygen consumption and the demand for H+, so the consumption of hydrogen fed into the PEMFC anode also increases accordingly. Figure 17 As shown, Figure 17 A cloud diagram of the consumption rate of anode hydrogen along the flow direction provided by the embodiment of the present disclosure is shown in FIG. Figure 17 The change in the anode hydrogen velocity shows that hydrogen is continuously consumed from the inlet to the outlet, and the velocity decreases accordingly. Furthermore, it is clearly evident that the hydrogen velocity in the variable-period three-dimensional wavy flow channel is lower at both the inlet and outlet sections than in the straight flow channel. This suggests that the variable-period three-dimensional wavy flow channel allows for more complete electrochemical reactions.

[0074] It can be seen that the embodiment of the present disclosure provides a variable-period three-dimensional wavy flow channel to explore the influence of the variable-period three-dimensional wavy flow channel on battery output performance, temperature, oxygen distribution, current density, liquid water distribution, etc., and reveals the basic principle of the variable-period three-dimensional wavy flow channel structure to improve mass transfer.

[0075] The research results show that with the increase of the depth of the variable period three-dimensional wavy flow channel, the current density and power density of PEMFC continue to increase. Especially when d = 1.2 mm, the battery performance is significantly improved, and its maximum power density is 6942.40 W / m 2 , relative to 6891.72W / m for d=1.0mm 2 Increased by 0.735%, relative to the direct current 6159.49W / m 2 An increase of 12.711%.

[0076] The variable-period three-dimensional wavy flow channel can significantly increase the diffusion rate of oxygen in the direction of the catalytic layer. The variable-period three-dimensional wavy flow channel causes forced convection of oxygen during the flow process, causing more oxygen to flow to the diffusion layer. Due to the reduction in the cross-sectional area of ​​the flow channel, the radial velocity increases. During the cross-sectional change process, a velocity difference will be formed, thereby forming a pressure difference between the inlet and outlet of the reaction gas and between the flow channel and the diffusion layer, thereby promoting the diffusion of oxygen.

[0077] The variable-period three-dimensional wavy flow channel experiences forced convection due to its variable cross-section. The oxygen concentration gradient between the lower portion of the channel and the ridge is smaller, indicating a more uniform oxygen distribution. Furthermore, it is evident that due to insufficient oxygen supply near the channel outlet, the oxygen concentration at the outlet is lower. However, the variable-period three-dimensional wavy flow channel, due to the more rapid change in the wave period at the outlet, has a higher oxygen concentration than the straight channel.

[0078] The reaction is more uniform in the variable-period three-dimensional wavy flow channel, oxygen diffuses more evenly, and the generated water removes most of the heat. Furthermore, it is clearly observed that the hydrogen velocity at both the inlet and outlet sections of the variable-period three-dimensional wavy flow channel is lower than that of the straight channel. This indicates that the variable-period three-dimensional wavy flow channel allows for a more complete electrochemical reaction.

[0079] The disclosed embodiment further provides a proton exchange membrane fuel cell, including an anode flow channel and a cathode flow channel, wherein the anode flow channel and the cathode flow channel adopt the above-mentioned proton exchange membrane fuel cell flow channel.

[0080] In an optional embodiment, the proton exchange membrane fuel cell further includes a proton exchange membrane, and the anode flow channel and the cathode flow channel are located on both sides of the proton exchange membrane.

[0081] Among them, proton exchange membrane refers to a polymer membrane that allows protons to pass through but blocks electrons and other ions.

[0082] The proton exchange membrane fuel cell is divided into a cathode and an anode with the proton exchange membrane as the center. The cathode side of the proton exchange membrane is provided with a cathode catalyst layer, a cathode diffusion layer, a cathode flow channel and a cathode current collecting plate, and the anode side of the proton exchange membrane is provided with an anode catalyst layer, an anode diffusion layer, an anode flow channel and an anode current collecting plate.

[0083] The cathode catalyst layer is the catalyst layer responsible for promoting the oxygen reduction reaction in a proton exchange membrane fuel cell. The cathode diffusion layer is located between the cathode catalyst layer and the cathode flow channel, and its purpose is to promote the uniform distribution and transport of the reactant gas (oxygen). The cathode flow channel refers to the gas flow channel on the cathode side of the bipolar plate, which is used to transport air (oxygen) and discharge generated water, while also promoting the diffusion of oxygen to the cathode catalyst layer. The cathode current collector is a component of the proton exchange membrane fuel cell, which is used to collect and conduct the current generated by the cathode and support the catalyst layer. The anode catalyst layer is the catalyst layer that promotes the hydrogen oxidation reaction in a proton exchange membrane fuel cell. The anode diffusion layer is located between the anode catalyst layer and the anode flow channel, which helps to evenly distribute hydrogen and improve reaction efficiency. The anode flow channel refers to the gas flow channel on the anode side of the bipolar plate, which is used to transport hydrogen and discharge unreacted residual gas, ensuring that hydrogen diffuses effectively to the anode catalyst layer. The anode current collector collects and conducts the current generated by the anode and provides support for the anode catalyst layer.

[0084] As mentioned above Figure 1 As shown, the proton exchange membrane fuel cell consists of 9 parts, which are divided into cathode and anode with the proton exchange membrane as the center. Correspondingly, the cathode is provided with a cathode catalyst layer, a cathode diffusion layer, a cathode flow channel and a cathode current collecting plate in sequence, and the anode is provided with an anode catalyst layer, an anode diffusion layer, an anode flow channel and an anode current collecting plate in sequence.

[0085] In the proton exchange membrane fuel cell provided in the embodiments of the present disclosure, since the anode flow channel and / or cathode flow channel located on both sides of the proton exchange membrane adopts the above-mentioned proton exchange membrane fuel cell flow channel, the diffusion rate in the direction of the oxygen catalyst layer can be increased, the distribution of oxygen can be more uniform, and the electrochemical reaction can be more sufficient, thereby improving the performance of the battery.

[0086] The foregoing description is intended only to provide specific embodiments of the present disclosure, intended to enable those skilled in the art to understand and implement the present disclosure. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure is not intended to be limited to the embodiments described herein, but rather to be construed in the broadest manner consistent with the principles and novel features disclosed herein.

Claims

1. A proton exchange membrane fuel cell flow channel, characterized in that: including cathode flow channels and anode flow channels provided on the bipolar plates; The cathode flow channel is a variable period three-dimensional wavy flow channel; And / or, the anode flow channel is the variable period three-dimensional wavy flow channel; The period of the outlet section of the variable-period three-dimensional wavy flow channel is smaller than the period of the inlet section of the variable-period three-dimensional wavy flow channel.

2. The proton exchange membrane fuel cell flow channel according to claim 1, characterized in that: The shape of the variable-period three-dimensional wavy flow channel is generated by a cosine function.

3. The proton exchange membrane fuel cell flow channel according to claim 1, characterized in that: The cosine function is y=b cos((0.01πx+a)x)+c, wherein x is the length of the flow channel, y is the height of any point on the variable period three-dimensional wavy flow channel, and a, b, and c are constants.

4. The proton exchange membrane fuel cell flow channel according to claim 1, characterized in that: The period of the variable-period three-dimensional wavy flow channel gradually decreases from the inlet to the outlet based on a piecewise function.

5. The proton exchange membrane fuel cell flow channel according to claim 1, characterized in that: The period of the variable-period three-dimensional wavy flow channel gradually decreases from the inlet to the outlet based on the interpolation method.

6. The proton exchange membrane fuel cell flow channel according to claim 1, characterized in that: The depth of the variable-period three-dimensional wavy flow channel is 1.2 mm.

7. The proton exchange membrane fuel cell flow channel according to claim 1, characterized in that: The length of the inlet section of the variable-period three-dimensional wavy flow channel is 3.0 mm, and the length of the outlet section of the variable-period three-dimensional wavy flow channel is 1.5 mm.

8. A proton exchange membrane fuel cell, characterized in that: The anode flow channel and the cathode flow channel are comprised, and the anode flow channel and the cathode flow channel are proton exchange membrane fuel cell flow channels as claimed in any one of claims 1 to 7.

9. The proton exchange membrane fuel cell according to claim 8, characterized in that: It also includes a proton exchange membrane, and the anode flow channel and the cathode flow channel are located on both sides of the proton exchange membrane.

10. The proton exchange membrane fuel cell according to claim 8, characterized in that: The proton exchange membrane fuel cell is divided into a cathode and an anode with the proton exchange membrane as the center. The cathode side of the proton exchange membrane is provided with a cathode catalyst layer, a cathode diffusion layer, a cathode flow channel and a cathode current collecting plate, and the anode side of the proton exchange membrane is provided with an anode catalyst layer, an anode diffusion layer, an anode flow channel and an anode current collecting plate.

Images