Fuel cell visualisation test apparatus

Abstract

The application discloses a fuel cell visual testing device. The metal flow field plate and the cathode end plate are respectively provided with hollow channels, and the visual window body is encapsulated by a window protection sleeve and placed in a rectangular groove. The visual window body and the encapsulated end plate are both transparent bodies, and the combination forms a constant temperature chamber. Four end surfaces of the cathode end plate are symmetrically provided with constant temperature gas and reactant inlet and outlet ports. The metal foam is compressed in the conductive area of the metal flow field plate, and the uncompressed part forms a metal foam flow field by the combination of the metal flow field plate and is used as a visual fuel cell unit. The anode end plate, the anode current collector plate, the anode graphite plate, the membrane electrode assembly, the metal flow field plate, the cathode end plate and the encapsulated end plate are sequentially fastened and sealed. The device can effectively and accurately reflect the liquid water transmission and distribution in the flow field of the fuel cell. The hollow area of the metal flow field plate can be changed to different areas or different flow field shapes according to the testing requirements, so that the on-line visual testing of the fuel cell is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fuel cells, in particular to a fuel cell direct visualization test device that can avoid condensation. BACKGROUND

[0002] Fuel cells have great application potential in the fields of automobiles, aviation, etc. due to their high energy density, power density, low noise, and zero emissions. Water transport is the only product of the electrochemical reaction of fuel cells, involving condensation, evaporation, electro-osmotic drag, and back diffusion processes. Dehydrated membrane electrodes can lead to high impedance, while excessive water in the flow field can cause the deactivation of fuel cells. Therefore, effective water management is crucial for fuel cell performance and durability. The main role of the flow field is to uniformly distribute the reactants on the membrane electrode and efficiently discharge liquid water. Analyzing the transport process and distribution of liquid water in the flow field using a visual fuel cell device is an important method for studying water management and further optimizing the flow field of the cell. The key issue is whether a visualization window can be opened to observe the structure of the membrane electrode surface and the flow channel without interfering with the internal transport process of the flow field. However, the current visual fuel cell visualization test device has the following shortcomings and limitations: (1) The temperature difference between the inside and outside of the visualization window is large, with the inside facing the flow field and the outside being the ambient temperature. A large temperature difference between the inside and outside can cause condensation on the inside of the window, directly interfering with the transport of gas-liquid two-phase in the flow field and affecting the actual transport process of the flow field. (2) The current observable flow field type is mainly the ridge and groove type flow field, and there are still many defects in the design scheme for visualizing the metal foam flow field. Therefore, developing a visualization test device suitable for different types of flow fields and capable of truly restoring the water transport characteristics in the flow channel is essential for the fuel cell research field.

[0003] Invention patent with application number CN202211414265.7 discloses a fuel cell visualization test device, which designs a visualization test device for a ridge and groove flow field fuel cell. This design scheme cannot effectively lead out the current after being applied to a metal foam flow field, and cannot meet the discharge requirements of new flow fields. Since a constant temperature chamber is not provided in the visualization window, the condensation phenomenon occurring on the flow field side window cannot observe the real transport process. Invention patent with application number CN201910740781.0 and utility model patent with application number 202120612938.4 still have the same problems as above. SUMMARY

[0004] In view of the defects of the current fuel cell visualization device, the purpose of the present application is to provide a fuel cell visualization test device that can avoid condensation.

[0005] The fuel cell visualization testing device includes: anode end plate, anode current collector plate, anode graphite plate, membrane electrode assembly, metal flow field plate, metal foam, and cathode end plate. Its technical solution is as follows:

[0006] The metal flow field plate has a hexagonal perforated channel at its center, with conductive areas on both sides. The cathode end plate has a rectangular perforated channel at its center, with a rectangular groove machined on one side and beveled on all four sides on the other side. A protective sleeve encapsulates the viewing window and places it within the rectangular groove. After assembly, the viewing window sealing gasket is flush with the viewing window, and the cathode end plate adheres to this plane for sealing, preventing gas and liquid leakage within the rectangular perforated channel. Both the viewing window and the encapsulation end plate are transparent, forming a constant temperature chamber. Symmetrically, constant temperature gas inlets and outlets, as well as reactant inlets and outlets, are located on the four ends of the cathode end plate. These two pairs of inlets and outlets communicate with the inner wall of the rectangular perforated channel of the cathode end plate. The anode end plate, anode current collector, anode graphite plate, membrane electrode assembly, metal flow field plate, metal foam, window sealing gasket, viewing window, viewing window protective sleeve, cathode end plate, and encapsulation end plate are sequentially tightened and sealed.

[0007] Furthermore, the conductive areas on both sides of the perforated channels of the metal flow field plate are bonded to the metal foam. The portion of the metal foam located within the conductive area of ​​the metal flow field plate is compressed to prevent reactants and liquid water from entering the conductive area of ​​the perforated channels. The combination of the metal flow field plate and the metal foam forms a metal foam flow field, which serves as a visualized fuel cell unit. Constant-temperature gas enters the constant-temperature chamber through the constant-temperature gas inlet, maintaining a consistent temperature within the visible window, and is continuously discharged through the exhaust port.

[0008] The features and beneficial effects of this invention are as follows:

[0009] (1) By designing the cathode end plate as a groove structure to form a constant temperature chamber, the problem of fogging caused by the temperature inconsistency between the inside and outside of the visualization window can be effectively solved, and the defect of condensation inside the window affecting optical imaging can be avoided. Thus, the transport characteristics and distribution state of liquid water in the fuel cell flow channel are truly restored, and the accuracy of the test is effectively improved.

[0010] (2) The metal flow field plate is divided into a hollow visible area and a conductive area. Based on the physical properties of metal foam, a sealed section is formed at the protrusion in the conductive area by compression deformation. Under the condition that the flow field area is not affected, the problem of metal foam current cannot be discharged is effectively solved.

[0011] (3) The fuel cell visualization test device has the advantages of simple structure, low processing cost and universality. It can be extended to the visualization test experiment of fuel cell online operation in different flow fields by modifying the height and shape of the metal flow field plate. Attached Figure Description

[0012] Figure 1 This is a schematic diagram showing the assembly and connection of the various components of the device of the present invention.

[0013] Figure 2 This is a schematic diagram of the side of the female end plate with a rectangular groove processed in this invention.

[0014] Figure 3 This is a schematic diagram of the side of the negative end plate of the present invention with a rectangular hollow channel bevel.

[0015] Figure 4 This is a schematic diagram of the assembly of the various components of the visualization window in this invention.

[0016] Figure 5 This is a schematic diagram of the metal flow field plate structure in this invention.

[0017] Figure 6 This is a photograph of the metal foam material used in this invention. Detailed Implementation

[0018] The structure of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Any further limitations or substitutions of equivalent function made based on the technical solution of the present invention shall fall within the protection scope of the present invention.

[0019] In the fuel cell visualization testing device, a hexagonal hollow channel 5-1 is formed in the center of the metal flow field plate 5, and conductive areas 5-2 are provided on both sides of the hexagonal hollow channel. A rectangular hollow channel 10-1 is formed in the center of the cathode end plate 10, and a rectangular groove 10-2 is machined on one side of the rectangular hollow channel of the cathode end plate; the four sides of the rectangular hollow channel of the other side are machined with bevels 10-3. The viewing window protective sleeve 9 encapsulates the viewing window 8 and places it in the rectangular groove. After assembly, the viewing window sealing gasket 7 is on the same plane as the viewing window, and the cathode end plate is attached to this plane for sealing to prevent gas and liquid leakage in the rectangular hollow channel. Both the viewing window and the encapsulation end plate 11 are transparent, and the combination of the viewing window and the encapsulation end plate forms a constant temperature chamber. The cathode end plate has two pairs of inlet and outlet ports symmetrically arranged on its four ends: a constant temperature gas inlet 10-4 and a constant temperature gas outlet 10-5, and a reactant inlet 10-6 and a reactant outlet 10-7. These inlets and outlets communicate with the inner wall of the rectangular hollow channel of the cathode end plate. The anode end plate 1, anode current collector 2, anode graphite plate 3, membrane electrode assembly 4, metal flow field plate, metal foam 6, viewing window sealing gasket, viewing window body, viewing window protective sleeve, cathode end plate, and encapsulation end plate are sequentially and tightly sealed.

[0020] The conductive areas on both sides of the hollowed-out channel of the metal flow field plate are bonded together with the metal foam. The metal foam is compressed in the part located in the conductive area of ​​the metal flow field plate to prevent reactants and liquid water from entering the conductive area of ​​the hollowed-out channel of the metal flow field plate. The combination of the metal flow field plate and the metal foam forms a metal foam flow field, which serves as a visualized fuel cell unit.

[0021] The conductive areas on both sides of the perforated channel of the metal flow field plate have a boss structure. The height of the boss is the same as the thickness of the fully compressed metal foam. The compressed metal foam forms a sealing surface in the boss area to prevent reactants and liquid water from entering the conductive area of ​​the metal flow field plate. The effective area of ​​the metal foam flow field is equal to the area of ​​the hexagonal perforated channel of the metal flow field plate.

[0022] The outer frame of the viewing window protective sleeve is the same size as the rectangular groove of the rectangular perforated channel on the cathode end plate, and the width of the rectangular perforated channel on the cathode end plate is greater than the uncompressed portion of the metal foam. The perforated channel of the metal flow field plate and the uncompressed portion of the metal foam serve as the metal foam flow field, thus enabling visual observation and testing of the metal foam flow field within the fuel cell. The angle between the bevel of the rectangular perforated channel on the cathode end plate and the horizontal plane is less than 60° to effectively avoid shadows during photography.

[0023] The surface of the metal flow field plate is gold-plated to effectively reduce the contact resistance between the metal flow field plate and the metal foam. The metal flow field plate features a hexagonal hollow channel at its center, with each of the six sides being symmetrically arranged. The metal flow field plate is equipped with a conductive interface for direct connection to the load.

[0024] The viewing window and encapsulation endplate are made of quartz glass, plexiglass, polystyrene, or polycarbonate.

[0025] The window sealing gasket and window protective cover are made of epoxy resin or fluororubber. The metal foam is either nickel foam, copper foam, or carbon foam.

[0026] The anode end plate, anode current collector, anode graphite plate, membrane electrode assembly, metal flow field plate, viewing window gasket, cathode end plate, and encapsulation end plate are all equipped with uniform positioning holes and are sealed by bolts.

[0027] As an example

[0028] The groove on the cathode end plate is square, and its depth must be less than the thickness of the viewing window protective sleeve; the height difference is equal to the thickness of the viewing window sealing gasket. The cutout dimensions of the viewing window protective sleeve are the same as those of the cathode end plate, both being larger than the uncompressed portion of the metal foam, thus achieving full flow field observability. The cutout dimensions of the viewing window protective sleeve are consistent with the structural dimensions of the viewing window.

[0029] The rectangular perforated channel of the cathode end plate has a 55° angle between its four beveled edges and the end plate plane to prevent shadows from being cast during testing and imaging, thus ensuring clear imaging. The height of the protrusions in the conductive area of ​​the metal flow field plate is related to the toughness of the metal foam material used; in this embodiment, it is half the thickness of the metal foam material. The viewing window and the encapsulated end plate are made of acrylic glass. The viewing window sealing gasket and the viewing window protective sleeve are made of epoxy resin.

[0030] The equipment used in the fuel cell visualization test process is a high-speed camera and a microscope to conduct online visualization experiments and research on the flow field region of metal foam.

[0031] like Figure 1 As shown, from left to right, the anode end plate, anode current collector, anode graphite plate, membrane electrode assembly, metal flow field plate, viewing window gasket, cathode end plate, and encapsulation end plate are assembled into a visible fuel cell unit by bolts through the positioning holes on each component.

[0032] Figure 2 and Figure 3 The structure of the cathode end plate is shown on both sides. One side of the rectangular perforated channel on the cathode end plate has a rectangular groove for placing the viewing window and its protective cover; the other side of the rectangular perforated channel has beveled edges. Eight positioning holes 12 on the outer ring of the end plate are used for sealing the device, and two small holes on the inner ring are used to fix the viewing window gasket. Furthermore, the inner wall of the rectangular perforated channel on the cathode (below the square groove) has four inlet and outlet ports located at the corners of the square groove, with the inlet and outlet ports diagonally opposite each other.

[0033] Figure 4 This is the assembly drawing of the visualization window section. The imaging area is formed by the groove of the cathode end plate, the window protective sleeve, and the visualization window itself. The window sealing gasket is used to prevent the leakage of reactants and liquid water at the visualization window plane.

[0034] Figure 5 The specific structure of the metal flow field plate is shown. The plate surface is divided into two parts: a hollow area and a conductive area. The metal flow field plate is made of gold-plated copper. The thickness of the flow field plate is the depth of the foam flow field. The side lengths of the hexagonal hollow channels are symmetrical in pairs.

[0035] Figure 6 Microscopic images of the metal foam are presented. The uncompressed portion of the metal foam represents the metal foam flow field, while the compressed portion is aligned with the height of the conductive step in the metal flow field plate, thus forming a sealing surface.

[0036] In this embodiment, nickel foam was selected as the metal foam, and gold plating was applied to the surface to prevent material corrosion from affecting the performance of the fuel cell.

[0037] The cathode end plate has a 52 mm × 52 mm perforated area on an aluminum plate, which is larger than the 50 mm × 50 mm perforated area of ​​the membrane electrode assembly's reaction region, effectively covering the fuel cell flow field area. The depth of the square groove on the cathode end plate is 10 mm, the height of the visualization window is 10 mm, the thickness of the interface between the window protective sleeve and the visualization window is 1 mm, and the thickness of the perforated window sealing gasket is also 1 mm. In this way, the encapsulation end plate exactly covers the plane of the visualization window.

[0038] After the visual window and its protective sleeve are combined, they are installed into the groove of the cathode end plate. The visual window sealing gasket fits snugly against the cathode end plate, and the size of the cutout area of ​​the window sealing gasket matches the size of the groove in the cathode end plate. Effective sealing is achieved through bolt clamping force and the sealing end plate.

[0039] This device has the advantages of simple structure and universality. By modifying the height and shape of the metal flow field plate, it can be extended to visualized test experiments of fuel cells operating online in different flow fields.

Claims

1. A fuel cell visualization testing device, comprising: The anode end plate, anode current collector, anode graphite plate, membrane electrode assembly, metal flow field plate, metal foam, and cathode end plate are characterized by: The metal flow field plate (5) has a hexagonal hollow channel (5-1) in the center, and conductive areas (5-2) are provided on both sides of the hexagonal hollow channel. The cathode end plate (10) has a rectangular hollow channel (10-1) in the center, and a rectangular groove (10-2) is processed on one side of the rectangular hollow channel of the cathode end plate; the four sides of the rectangular hollow channel on the other side are beveled (10-3). The window protective sleeve (9) encapsulates the visible window (8) and places it in the rectangular groove. After assembly, the window sealing gasket (7) is on the same plane as the visible window. The cathode end plate is attached to this plane for sealing to prevent gas and liquid leakage in the rectangular hollow channel. The visible window and the sealing gasket are sealed together. The end plates (11) are all transparent bodies, and the constant temperature chamber is formed by combining the viewing window and the encapsulation end plate. The constant temperature gas inlet (10-4) and constant temperature gas exhaust (10-5), as well as the reactant inlet (10-6) and reactant exhaust (10-7) are symmetrically provided on the four end faces of the cathode end plate. The two pairs of inlet and exhaust ports are connected to the inner wall of the rectangular hollow channel of the cathode end plate. The anode end plate (1), anode current collector (2), anode graphite plate (3), membrane electrode assembly (4), metal flow field plate, metal foam (6), viewing window sealing gasket, viewing window, viewing window protective sleeve, cathode end plate and encapsulation end plate are sequentially tightened and sealed. The conductive areas on both sides of the hollowed-out channel of the metal flow field plate are bonded together with the metal foam. The metal foam is compressed in the part located in the conductive area of ​​the metal flow field plate to prevent reactants and liquid water from entering the conductive area of ​​the hollowed-out channel of the metal flow field plate. The combination of the metal flow field plate and the metal foam forms a metal foam flow field, which serves as a visualized fuel cell unit. The conductive areas on both sides of the hollowed-out channel of the metal flow field plate are protrusion structures. The height of the protrusion is the same as the thickness of the metal foam after it is fully compressed. The compressed metal foam forms a sealing surface in the protrusion area to prevent reactants and liquid water from entering the conductive area of ​​the metal flow field plate. The effective area of ​​the metal foam flow field is equal to the area of ​​the hexagonal hollowed-out channel of the metal flow field plate. The outer frame of the viewing window protective sleeve is equal in size to the rectangular groove of the rectangular hollow channel of the cathode end plate, and the width of the rectangular hollow channel of the cathode end plate is greater than the uncompressed part of the metal foam. The hollow channel of the metal flow field plate and the uncompressed part of the metal foam serve as the metal foam flow field, thereby enabling visual observation and testing of the metal foam flow field inside the fuel cell.

2. The fuel cell visualization testing device according to claim 1, characterized in that: The angle between the rectangular hollow channel bevel of the negative end plate and the horizontal plane is less than 60°, so as to effectively avoid shadows during shooting.

3. The fuel cell visualization testing device according to claim 1, characterized in that: The surface of the metal flow field plate is gold-plated to effectively reduce the contact resistance between the metal flow field plate and the metal foam. The metal flow field plate is provided with a conductive interface for direct connection to the load.

4. The fuel cell visualization testing device according to claim 1, characterized in that: The viewing window and the encapsulation end plate are made of quartz glass; or plexiglass; or polystyrene; or polycarbonate.

5. The fuel cell visualization testing device according to claim 1, characterized in that: The window sealing gasket and window protective cover are made of epoxy resin or fluororubber, and the metal foam is made of nickel foam or copper foam.

6. The fuel cell visualization testing device according to claim 1, characterized in that: The anode end plate, anode current collector plate, anode graphite plate, membrane electrode assembly, metal flow field plate, window sealing gasket, cathode end plate, and encapsulation end plate are all provided with uniform positioning holes (12), which are sealed by bolts.

7. The fuel cell visualization testing device according to claim 1, characterized in that: The hexagonal hollow channel at the center of the metal flow field plate has six sides that are symmetrical in pairs.

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