A liquid storage device for testing vanadium flow battery stack

Abstract

This application relates to a liquid storage device for testing vanadium redox flow battery stacks, belonging to the technical field of flow batteries. The liquid storage device includes two manifolds, which are spaced apart vertically; and several liquid storage channel mechanisms. Each liquid storage channel mechanism includes a support frame and a spiral channel tube. The support frame is vertically positioned, and the spiral channel tube is located within and connected to the support frame. The spiral channel tube is vertically positioned and spirally wound vertically. The lower end of the spiral channel tube is connected to one manifold, and the upper end is connected to the other manifold. The manifold located below the spiral channel tube is used to input electrolyte into the spiral channel tube, and the other manifold is used to output electrolyte from the spiral channel tube. This application reduces electrolyte backmixing and the occurrence of flow dead zones within the liquid storage device, thereby improving the accuracy of stack testing results.

Description

Technical Field

[0001] This application relates to the technical field of flow batteries, and in particular to a liquid storage device for testing an all-vanadium redox flow battery stack. Background Technology

[0002] Vanadium redox flow batteries, as a large-scale electrochemical energy storage technology, play a vital role in smart grid construction and renewable energy consumption due to their advantages such as long cycle life, high safety, and independent design of power and capacity. In a flow battery, the electrolyte storage device mainly functions to store the positive and negative electrode electrolytes. During operation, the electrolyte storage device works in conjunction with a circulation pump to maintain the continuous circulation of electrolyte between the battery stack and the storage device.

[0003] Currently, in existing vanadium redox flow battery systems, especially in experimental rigs used for stack testing of flow batteries, the electrolyte storage device mostly adopts a cylindrical or box-shaped cavity structure. During flow battery stack testing, the storage device feeds the electrolyte into the stack, while the electrolyte, after passing through the stack reaction, flows back into the storage device. In the storage device, the returned electrolyte merges and mixes with the existing electrolyte. Subsequently, a circulation pump draws the mixed electrolyte from the storage device again and delivers it to the stack, thus forming a closed charge-discharge cycle test loop.

[0004] Regarding the aforementioned technologies, existing electrolyte storage devices have a large-volume cavity, which exhibits a completely mixed flow (CSTR) characteristic in terms of fluid dynamics. This means that when the electrolyte enters or exits the storage device, the low-energy electrolyte that has just returned to the storage device will quickly mix with the existing high-energy electrolyte. Simultaneously, due to the uneven flow velocity distribution within the large-volume cavity, dead zones easily form at the corners, causing some electrolyte to remain stagnant and unable to participate in circulation. This disordered flow state causes drastic fluctuations and uneven distribution of the state of charge (SOC) of the electrolyte delivered to the fuel cell stack. This makes it difficult to maintain stable electrochemical reaction conditions for the electrolyte output to the stack, resulting in unstable voltage readings and signal lag and distortion in the test data. Consequently, the data cannot accurately reflect the true transient performance of the fuel cell stack under a specific charge state. Summary of the Invention

[0005] This application provides a liquid storage device for testing vanadium redox flow battery stacks. The purpose of this device is to improve the flow state of the electrolyte during the storage process by designing the structure of the storage device, thereby reducing electrolyte back-mixing and the occurrence of flow dead zones, and thus improving the accuracy of the stack test results.

[0006] This application provides a liquid storage device for testing a vanadium redox flow battery stack, employing the following technical solution: A liquid storage device for testing a vanadium redox flow battery stack includes two manifolds, which are spaced apart vertically; a liquid storage channel mechanism, comprising a plurality of such mechanisms; each liquid storage channel mechanism includes a support frame and a spiral channel pipe, wherein the support frame is vertically arranged, the spiral channel pipe is located within and connected to the support frame, the spiral channel pipe is vertically arranged and spirally coiled vertically, the lower end of the spiral channel pipe is connected to one of the manifolds, and the upper end is connected to the other manifold; the manifold located below the spiral channel pipe is used to input electrolyte into the spiral channel pipe, and the other manifold is used to output electrolyte from the spiral channel pipe.

[0007] By adopting the above technical solution, with the cooperation of two manifolds and several liquid storage channels, the electrolyte enters the lower end of the spiral channel tube through the lower manifold. After the electrolyte gradually fills the spiral channel tube from bottom to top, the electrolyte flows out from the upper end of the spiral channel tube into the upper manifold, and finally flows out through the corresponding manifold.

[0008] Based on the structural design of the helical flow channel, when the electrolyte flows as a fluid within the helical flow channel, on the one hand, the helical structure increases the length-to-diameter ratio of the flow channel, forcing the fluid to form a near-ideal piston flow state within the helical flow channel. This ensures that the fluid entering the helical flow channel at different times can advance axially in strict chronological order, thereby minimizing axial dispersion and effectively suppressing axial backmixing of new and old fluids. This ensures that the fluid concentration output to the fuel cell stack changes linearly with time, truly reflecting the testing process. On the other hand, when the fluid flows through the helical tube, the centrifugal force induces secondary flow, namely Dean vortices, on the cross-section of the tube. The formation of Dean vortices promotes orderly radial circulation of the fluid within the tube cross-section, effectively suppressing the velocity difference between the fluid center and the edge. This makes the flow state within the helical flow channel closer to the ideal piston flow, resulting in a more uniform temperature and concentration distribution of the fluid on the corresponding cross-section within the helical flow channel.

[0009] Therefore, with this design, the liquid storage device can continuously supply the stack with a stable and homogeneous electrolyte, thereby improving the stack voltage fluctuations and test data distortion caused by the disordered flow field inside the liquid storage device, thus improving the accuracy of stack performance test results and the overall energy efficiency of the flow battery.

[0010] Optionally, the main manifold is provided with a plurality of interface pipes, which are arranged sequentially along the length of the main manifold. The interface pipes are connected to the main manifold, and an isolation valve is provided on each interface pipe. The isolation valve is used to open or close the corresponding interface pipe. The upper and lower ends of the spiral flow channel pipe are respectively connected to the corresponding interface pipe.

[0011] By adopting the above technical solution, the cooperation between the interface pipe and the isolation valve enables independent control of the on / off state of a single spiral flow channel pipe. When a spiral flow channel pipe becomes blocked, leaks, or needs to be replaced, the corresponding isolation valve can be closed to cut off the corresponding spiral flow channel pipe, while other spiral flow channel pipes can operate normally. This improves the reliability and fault tolerance of the liquid storage device.

[0012] Optionally, the spiral flow channel tube is detachably connected to the corresponding interface tube.

[0013] By adopting the above technical solution, the detachable connection design allows the spiral flow channel tube to be quickly disassembled, replaced, or maintained as an independent module.

[0014] Optionally, the manifold is provided with a plurality of partition valves, which are arranged at intervals along the length of the manifold, and the partition valves and the interface pipes are arranged alternately along the length of the manifold. The partition valves are used to open or close the manifold.

[0015] By adopting the above technical solution, the manifold is physically divided into several independent sections using a dividing valve. Each section is connected to a spiral flow channel pipe. Thus, when different capacity tests are required or when some spiral flow channel pipes need to be isolated for maintenance, several spiral flow channel pipes can be isolated from the liquid storage device by closing specific dividing valves. This design improves the flexibility of the liquid storage device, enabling it to adapt to the testing requirements of fuel cell stacks with different power specifications.

[0016] Meanwhile, the design of the separator valve can cut off the non-working portion of the manifold, thereby eliminating blind sections or flow dead zones at the end of the manifold. This effectively prevents the static electrolyte remaining in the non-working section from slowly mixing with the dynamic electrolyte in the working section through diffusion, avoiding electrolyte concentration tailing or signal delay caused by this. This ensures that the storage device can maintain a pure flow field environment and high test data confidence under variable capacity conditions, especially when conducting small-capacity stack tests.

[0017] Optionally, the support frame includes several splicing frames, which are stacked sequentially in a vertical direction; the spiral flow channel includes several spiral branch pipes, which are arranged in a one-to-one correspondence with the splicing frames, and are located within and connected to the splicing frames; the spiral branch pipes are sequentially connected and detachably connected in a vertical direction, and the uppermost spiral branch pipe is connected and detachably connected to one of the main flow channels, and the lowermost spiral branch pipe is connected and detachably connected to another main flow channel.

[0018] By adopting the above technical solution, and through the standardized splicing frame and spiral branch pipe design, the splicing frame and corresponding spiral branch pipe form an independent flow channel module. Several flow channel modules are vertically stacked and connected to form a corresponding liquid storage flow channel mechanism. This design not only facilitates the transportation and on-site assembly of the liquid storage device, but also allows users to freely adjust the number of flow channel modules in a single liquid storage flow channel mechanism according to testing requirements. This allows for free adjustment of the length of a single spiral flow channel, correspondingly changing the capacity of the liquid storage device. Therefore, the liquid storage device can achieve flexible configuration of liquid storage capacity and effective flow, thereby matching the fluid circulation volume and reaction residence time required by different power specifications of the battery stack. This ensures that the liquid battery stack maintains ideal flow state and concentration uniformity under different test scales, avoiding test errors caused by mismatch between the capacity of the liquid storage device and the test object.

[0019] Optionally, the liquid storage channel mechanism further includes a bridging pipe network, which includes a main pipe and a first pipe and a second pipe disposed between the spiral branch pipe and the main pipe; the main pipe is vertically arranged and located between two manifolds, and both ends of the main pipe are respectively connected to the two manifolds; a first valve is provided on both the first pipe and the second pipe, one end of the first pipe is connected to the main pipe and the other end is connected to one end of the corresponding spiral branch pipe and is detachably connected; one end of the second pipe is connected to the main pipe and the other end is connected to the other end of the corresponding spiral branch pipe and is detachably connected; a plurality of second valves are provided on the main pipe, and the second valves are arranged one-to-one with the spiral branch pipes, and the second valves are located vertically between the connection points of the corresponding first pipe and the main pipe and the connection points of the corresponding second pipe and the main pipe.

[0020] By adopting the above technical solution and utilizing the coordinated design of the main pipe, first pipe, second pipe and first valve in the bridge pipe network, when it is necessary to connect to a certain spiral branch pipe, the corresponding second valve on the main pipe is closed and the first valves on both sides are opened. At this time, the main pipe is cut off, so that the fluid in the main pipe flows through the corresponding spiral branch pipe. When it is necessary to isolate a certain spiral branch pipe, the corresponding second valve is opened and the two first valves are closed. At this time, the main pipe is open, and the corresponding first pipe and second pipe are cut off. The fluid can only flow through the main pipe and thus skip the corresponding spiral branch pipe.

[0021] This design enables dynamic reconfiguration of the internal flow path topology of the liquid storage channel mechanism. It can not only isolate one or more spiral branch tubes in the online manner without interrupting the overall test, but also flexibly adjust the effective total length of a single spiral flow channel tube to match the different requirements of different fuel cell stack tests for reaction residence time and circulation volume.

[0022] Optionally, a flow reset pipe is provided between the spiral branch pipe and the first pipe. One end of the flow reset pipe is connected to the first pipe, and the other end is connected to one end of the corresponding spiral branch pipe and can be detachably connected. The inner diameter of the middle part of the flow reset pipe along its own length direction is smaller than the inner diameters at both ends.

[0023] By adopting the above technical solution, the flow reset pipe utilizes its narrowed inner diameter to create a Venturi effect. When fluid flows between the first pipe and the spiral branch pipe, the velocity increases instantaneously and the pressure decreases at the narrowed section of the flow reset pipe, generating strong flow field disturbances and shear forces. This hydrodynamic effect effectively breaks up the laminar boundary layer formed during pipeline transportation, i.e., the parabolic velocity distribution, forcing the fluid to undergo sufficient radial mixing and recombination across the pipe cross-section. This is equivalent to initializing or resetting the flow field at the inlet or outlet of each stage of the spiral branch pipe, eliminating the velocity gradient and concentration stratification accumulated on the cross-section of the fluid in the previous stage of the pipeline, ensuring that the fluid entering the spiral branch pipe has a highly uniform initial concentration and velocity distribution across the cross-section, thereby effectively suppressing axial dispersion and tailing phenomena that may occur during long-distance transportation.

[0024] Optionally, the spiral flow channel tube is provided with an embedded turbulence-inducing component, which includes a turbulence-inducing hose. The turbulence-inducing hose is coaxially disposed inside the spiral flow channel tube, with its outer sidewall spaced apart from the inner sidewall of the spiral flow channel tube. Both ends of the turbulence-inducing hose are sealed to the inner sidewall of the spiral flow channel tube.

[0025] By adopting the above technical solution, a turbulence-inducing hose is coaxially installed inside the spiral flow channel. When the fluid passes through the turbulence-inducing hose, the hose will oscillate or vibrate slightly under the scouring of the fluid. This physical vibration can directly interfere with and destroy the laminar boundary layer of the fluid near the pipe wall of the turbulence-inducing hose, forcing the boundary layer fluid to exchange with the main fluid in the central layer. This further eliminates the flow stagnation layer of the fluid on the inner wall of the turbulence-inducing hose, effectively smooths the velocity gradient on the fluid cross-section, improves the tailing phenomenon caused by the slow flow velocity of the fluid inside the turbulence-inducing hose, and ensures that the fluid can still maintain a uniform propulsion speed and move forward under low flow velocity conditions.

[0026] Optionally, a support spring is coaxially sleeved on the outside of the turbulence hose, the support spring is connected to the turbulence hose, and the support spring is spaced apart from the inner wall of the spiral flow channel.

[0027] By adopting the above technical solution, the support spring has a supporting function and can improve the elasticity of the turbulence hose, so that the turbulence hose always stays on the central axis of the spiral flow channel tube, preventing the turbulence hose from sticking to the tube wall of the spiral flow channel tube due to bending or fluid impact, causing flow channel blockage or vibration failure; at the same time, the elastic modulus of the support spring can adjust the vibration frequency of the turbulence hose, making it easier to resonate at a specific working flow rate, thereby improving the physical disturbance effect on the fluid boundary layer.

[0028] Optionally, a fluid shaping component is provided inside the spiral flow channel tube. The fluid shaping component includes a shaping flow channel tube, which is coaxially disposed inside the spiral flow channel tube. The shaping flow channel tube is connected to the inner wall of the spiral flow channel tube, and the cross-section of the shaping flow channel tube at its midpoint along its length is elliptical.

[0029] By adopting the above technical solution, the shaping flow channel is coaxially set inside the spiral flow channel, and the middle part of the shaping flow channel is designed to be elliptical. As the fluid passes through the shaping flow channel, the cross-sectional shape of the fluid flow is forced to smoothly transition from a circle to an ellipse. This change in cross-sectional geometry causes the streamlines to twist and fold, breaking the original Dean vortex symmetry in the spiral flow channel and inducing chaotic convection on the fluid cross-section. This achieves full-domain mixing of fluid particles throughout the entire cross-section, thereby further improving the macroscopic mixing blind zone on the fluid cross-section.

[0030] In summary, this application includes at least one of the following beneficial technical effects:

[0031] 1. This application improves the flow state of the electrolyte during the storage process by using a combination of two manifolds and several spiral flow channels, thereby reducing electrolyte backmixing and the occurrence of flow dead zones in the storage device, thus improving the accuracy of stack testing and the energy efficiency of the flow battery.

[0032] 2. This application, through the combined design of the interface pipe, isolation valve, and separation valve on the manifold, can control the connection of the spiral flow channel pipe to the liquid storage device or its isolation from the liquid storage device. This makes the capacity of the liquid storage device adjustable, thereby improving the flexibility of the liquid storage device and enabling it to adapt to the testing requirements of fuel cell stacks with different power specifications.

[0033] 3. This application utilizes the synergistic effect of a flow regime reset tube, a flow disturbance hose, and a flow channel shaping tube to deeply optimize the flow regime at three dimensions: the flow channel connection, the boundary layer near the tube wall, and the macroscopic cross-section of the fluid. This multi-scale mixing enhancement mechanism effectively improves the velocity gradient, temperature gradient, concentration gradient, and mixing blind zone of the electrolyte on the cross-section of the helical flow channel, improves the thermal management performance of the storage device, and effectively prevents side reactions caused by local overheating or additive deposition. It ensures that the electrolyte maintains a highly uniform flow state under long-distance transportation and low-flow-rate conditions, thereby more accurately reflecting the true transient electrochemical performance of the fuel cell stack. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the overall structure of the liquid storage device in Embodiment 1 of this application.

[0035] Figure 2 This is a schematic diagram of the overall structure of the liquid storage channel mechanism in Embodiment 1 of this application.

[0036] Figure 3 This is a schematic diagram of the overall structure of the liquid storage channel mechanism in Embodiment 2 of this application.

[0037] Figure 4 This is a schematic diagram of the overall structure of the flow channel module in Embodiment 2 of this application.

[0038] Figure 5 This is a partial structural schematic diagram of the liquid storage device of Embodiment 3 of this application.

[0039] Figure 6 This is a schematic diagram of the overall structure of the flow channel module in Embodiment 3 of this application.

[0040] Figure 7 This is a partial structural schematic diagram of the spiral branch pipe of Embodiment 3 of this application.

[0041] Figure 8 This is a cross-sectional view of a straight pipe with a turbulence-reducing hose installed in Embodiment 4 of this application.

[0042] Figure 9 This is a cross-sectional view of a straight pipe with a shaping flow channel installed in Embodiment 4 of this application.

[0043] Figure 10This is a schematic diagram of the internal structure of the shaping flow channel tube in Embodiment 4 of this application.

[0044] In the diagram, 1. Main manifold; 11. Interface pipe; 12. Isolation valve; 13. Separation valve; 2. Liquid storage channel mechanism; 3. Support frame; 31. Splicing frame; 32. Layer plate; 4. Spiral channel pipe; 41. Spiral branch pipe; 411. Rotary pipe; 4111. Straight pipe; 4112. Right-angle pipe; 412. Interlayer pipe; 413. Discharge pipe; 414. Inlet pipe; 5. Channel module; 6. Bridging pipe network; 61. Main pipe; 62. First pipe; 63. Second pipe; 64. First valve; 65. Second valve; 7. Flow reset pipe; 8. Embedded turbulence component; 81. Turbulence hose; 82. Support spring; 9. Fluid shaping component; 91. Shaping channel pipe. Detailed Implementation

[0045] The following is in conjunction with the appendix Figure 1 -Appendix Figure 10 This application will be described in further detail below.

[0046] Example 1: A liquid storage device for testing a vanadium redox flow battery stack, referring to... Figure 1 and Figure 2 It includes two manifolds 1 and several liquid storage channels 2. The manifolds 1 are horizontally arranged, and the two manifolds 1 are spaced apart vertically. The liquid storage channel 2 includes a support frame 3 and a spiral channel pipe 4. The support frame 3 is vertically arranged, and the spiral channel pipe 4 is located inside and connected to the support frame 3. The spiral channel pipe 4 is vertically arranged, and its upper end spirals upward in the vertical direction. The lower end of the spiral channel pipe 4 is connected to one manifold 1, and its upper end is connected to the other manifold 1.

[0047] Reference Figure 1 The main manifold 1 is provided with several interface pipes 11, one end of which is connected to the corresponding main manifold 1. The interface pipes 11 are arranged sequentially along the length of the main manifold 1, and each interface pipe 11 is equipped with an isolation valve 12. The main manifold 1 is also provided with several separation valves 13, which are arranged alternately with the interface pipes 11 along the length of the corresponding main manifold 1.

[0048] Reference Figure 1 The upper and lower ends of the spiral flow channel pipe 4 are respectively connected to the corresponding interface pipe 11 and are detachably connected, and there is a separation valve 13 between two adjacent spiral flow channel pipes 4.

[0049] In this embodiment, the isolation valve 12 is a corrosion-resistant manual ball valve, electric ball valve, or pneumatic diaphragm valve. The separation valve 13 is a corrosion-resistant butterfly valve or gate valve. The interface pipe 11 and the spiral flow channel pipe 4 are connected by a flange or a PVC / CPVC union to achieve quick disassembly and maintenance.

[0050] With this design, when a spiral flow channel tube 4 needs to be replaced or cleaned, closing the isolation valves 12 at both ends of the corresponding spiral flow channel tube 4 will isolate the spiral flow channel tube 4 from the liquid storage device, while other spiral flow channel tubes 4 can operate normally.

[0051] When testing fuel cell stacks with different power specifications, such as switching from a low-power stack to a high-power stack, the number of spiral flow channels 4 connected to the liquid storage device can be adjusted by opening or closing the separator valve 13 on the main manifold 1. This expansion capability can improve the testing error problem caused by the mismatch between the capacity of the liquid storage device and the test object.

[0052] In this embodiment, to adapt to the strong corrosiveness of the vanadium redox flow battery electrolyte, the spiral flow channel 4 is made of an acid-resistant material, such as chlorinated polyvinyl chloride (CPVC) or polyvinylidene fluoride (PVDF). The inner diameter of the spiral flow channel 4 is specifically matched with the spiral curvature radius, so that the electrolyte can form an approximate piston flow at the test operating flow rate. At the same time, centrifugal force is used to form Dean vortices in the cross-section of the spiral flow channel 4 to enhance the radial mixing of the electrolyte in the cross-section of the spiral flow channel 4.

[0053] Reference Figure 1 In this embodiment, the liquid storage device also includes auxiliary detection components, which include several pressure gauges, several temperature sensors, and several flow meters. These pressure gauges, temperature sensors, and flow meters are distributed on the main manifold 1 and the spiral flow channel 4, enabling them to collect pressure, temperature, and flow rate data of the electrolyte throughout the liquid storage device. Furthermore, the pressure gauges, temperature sensors, and flow meters are all connected to the controller via communication or data cables, allowing the controller to monitor the operating status of the entire liquid storage device in real time and promptly detect changes in the testing environment.

[0054] The implementation principle of this application embodiment is as follows: When the battery stack is tested, the electrolyte is transported as a fluid through the lower manifold 1 to several parallel spiral flow channel pipes 4. At this time, the large length-to-diameter ratio of the spiral flow channel pipe 4 is used to force the fluid to form a macroscopically ordered flow in the spiral flow channel pipe 4, that is, an approximately ideal piston flow state. This flow state ensures that the fluid entering the spiral flow channel pipe 4 at different times can advance axially in strict time sequence, effectively suppressing the axial back mixing of the fluid in the spiral flow channel pipe 4, thereby making the electrolyte concentration output to the battery stack show a highly linear change with time.

[0055] Based on this, when the fluid flows through the spiral flow channel 4, the centrifugal force generated by the spiral structure of the spiral flow channel 4 acts on the fluid, thereby inducing Dean vortices on the cross-section of the fluid within the spiral flow channel 4. As an ordered secondary flow, Dean vortices enhance the heat and mass exchange of the fluid on the cross-section, homogenize the flow velocity at various points on the same cross-section, and eliminate the radial concentration gradient and temperature gradient on the same cross-section of the fluid, thus further approximating the ideal piston flow model, thereby improving the consistency of the electrolyte output to the stack and the accuracy of the test data.

[0056] Example 2: A liquid storage device for testing a vanadium redox flow battery stack, referring to... Figure 3 and Figure 4 The difference between this embodiment and embodiment 1 is that the liquid storage channel mechanism 2 includes several channel modules 5. The channel module 5 includes a splicing frame 31 and a spiral branch pipe 41. The splicing frame 31 and the spiral branch pipe 41 are arranged in a one-to-one correspondence, and the spiral branch pipe 41 is located in the corresponding splicing frame 31 and is connected to the corresponding splicing frame 31.

[0057] Reference Figure 3 and Figure 4 Several splicing frames 31 are stacked vertically in sequence, and adjacent splicing frames 31 are detachably connected. Several spiral branch pipes 41 are connected vertically in sequence and are detachably connected.

[0058] Reference Figure 1 and Figure 3 Since several splicing frames 31 are assembled to form a support frame 3, and several spiral branch pipes 41 are connected in sequence to form a spiral flow channel pipe 4, the upper end of the uppermost spiral branch pipe 41 is connected to the corresponding interface pipe 11 on the upper main pipe 1 and can be detached, and the lower end of the lowermost spiral branch pipe 41 is connected to the corresponding interface pipe 11 on the lower main pipe 1 and can be detached.

[0059] In this embodiment, refer to Figure 3 and Figure 4 Adjacent splicing frames 31 are connected by bolt assemblies or quick-release clips. Spiral branch pipes 41 are connected to adjacent spiral branch pipes 41 or interface pipes 11 by flanges or PVC / CPVC unions.

[0060] The implementation principle of this application embodiment is as follows: through the cooperation of the standardized splicing frame 31 and the spiral branch pipe 41, the number of stacked flow channel modules 5 can be freely increased or decreased according to the test requirements, and the length of the spiral flow channel pipe 4 in a single liquid storage flow channel mechanism 2 can be changed, which can change the capacity of the entire liquid storage device.

[0061] When testing high-power fuel cell stacks and requiring a longer reaction residence time, the number of stacked layers of flow channel modules 5 within each liquid storage flow channel mechanism 2 can be increased to extend the total length and total volume of the spiral flow channel tube 4; conversely, when testing low-power fuel cell stacks, the number of layers can be reduced to avoid electrolyte waste and response lag.

[0062] This design enables flexible configuration of the storage capacity and effective flow, thereby matching the electrolyte circulation volume and reaction residence time required by different power specifications of the fuel cell stack, ensuring that the storage device can maintain an ideal flow state under different test scales.

[0063] Example 3: A liquid storage device for testing a vanadium redox flow battery stack, referring to... Figure 5 The difference between this embodiment and embodiment 2 is that the liquid storage channel mechanism 2 also includes a bridging pipe mesh 6, which is arranged horizontally at intervals on one side of several stacked channel modules 5.

[0064] Reference Figure 5 The bridge pipe network 6 includes a main pipe 61, which is vertically arranged. The upper end of the main pipe 61 is coaxially connected to the interface pipe 11 on the corresponding main pipe 1 and is detachably connected. The lower end of the main pipe 61 is coaxially connected to the interface pipe 11 on another main pipe 1 and is detachably connected.

[0065] Reference Figure 5 A first pipe 62 and a second pipe 63 are provided between the flow channel module 5 and the main pipe 61. Specifically, one end of the first pipe 62 is connected to the main pipe 61, and the other end is connected to the lower end of the corresponding spiral branch pipe 41; one end of the second pipe 63 is connected to the main pipe 61, and the other end is connected to the upper end of the corresponding spiral branch pipe 41. A first valve 64 is provided on both the first pipe 62 and the second pipe 63. Several second valves 65 are provided on the main pipe 61. The several second valves 65 are arranged sequentially at intervals along the vertical direction, and the second valves 65 are arranged one-to-one with the spiral branch pipes 41. The second valves 65 are located between the corresponding first pipes 62 and second pipes 63 along the length of the main pipe 61.

[0066] In this embodiment, both the first valve 64 and the second valve 65 can be corrosion-resistant solenoid valves, corrosion-resistant electric ball valves, or manual ball valves. When the first valve 64 or the second valve 65 is an electric valve, both the first valve 64 and the second valve 65 are electrically connected to the controller. At this time, the controller can automatically output control signals to change the opening and closing states of the first valve 64 and the second valve 65 according to the preset test program or the real-time monitored flow requirements, thereby realizing the automatic switching of the flow path topology. When the first valve 64 and the second valve 65 are manual valves, the operator can manually open or close the corresponding first valve 64 and the second valve 65 according to the experimental requirements, thereby realizing the manual switching of the flow path.

[0067] In this embodiment, it should be noted that, considering the significant difference in flow resistance between the spiral branch pipe 41 and the main pipe 61, to avoid hydraulic shock damage to the pipeline during valve switching, a control strategy of first reducing the frequency, then switching, and finally restoring is adopted when switching the flow path. Specifically, after receiving the flow path switching command, the controller first controls the circulating pump to reduce its speed to decrease the static pressure and flow velocity in the pipeline; after the flow velocity drops to a safe threshold, it then controls the first valve 64 and the second valve 65 to complete the flow path switching; finally, it controls the circulating pump to gradually return to the set speed. In addition, a back pressure valve or a hydraulic accumulator can be installed at the output end of the main manifold 1 to further absorb the transient pressure fluctuations that may occur during the flow path switching process and ensure the stability of the test process.

[0068] Reference Figure 5 Each of the first pipe 62 and the second pipe 63 is provided with a flow reset pipe 7 between it and the corresponding spiral branch pipe 41. One end of the flow reset pipe 7 is coaxially connected to the corresponding first pipe 62 or second pipe 63 and is detachably connected. The other end of the flow reset pipe 7 is coaxially connected to the corresponding end of the spiral branch pipe 41 and is detachably connected. The inner diameter of the flow reset pipe 7 at its middle along its length is smaller than the inner diameter at both ends of the flow reset pipe 7.

[0069] Under the structural design of the flow reset tube 7, when the electrolyte flows through the flow reset tube 7, the reduced inner diameter in the middle of the flow reset tube 7 forces the flow cross section of the electrolyte to shrink, which in turn causes the electrolyte to increase in flow velocity and decrease in static pressure when it flows through the reduced diameter position. This makes the flow reset tube 7 have the structural characteristics of a Venturi tube and can induce the Venturi effect.

[0070] Under this principle, when fluid enters the spiral branch pipe 41 and flows through the narrowing of the flow reset pipe 7, the fluid velocity increases instantaneously and the pressure decreases due to the Venturi effect, thus inducing strong local turbulence on the fluid cross-section downstream of the flow reset pipe 7. This turbulence effectively breaks up the laminar boundary layer formed by viscous retention in the previous stage pipe, i.e., the parabolic velocity distribution, forcing the fluid to undergo intense radial exchange and recombination on the pipe cross-section. This is equivalent to the flow reset pipe 7 eliminating the accumulation of velocity gradients caused by long-distance laminar transport on the cross-section of the fluid at the inlet and outlet of each flow channel module 5, thereby improving the axial tailing phenomenon of the fluid in the pipe and ensuring that the fluid entering the next stage flow channel has a highly uniform initial state on the cross-section.

[0071] In this embodiment, to prevent cavitation due to excessively low pressure when the fluid flows through the narrowing section of the flow reset pipe 7, the ratio of the inner diameter of the narrowing section to the inner diameters at both ends of the flow reset pipe 7 is calculated to ensure that the static pressure at the narrowing section is still higher than the saturated vapor pressure of the electrolyte at the maximum design flow rate. Furthermore, both the narrowing and widening sections of the flow reset pipe 7 adopt a streamlined, smooth transition design, with the widening angle controlled between 7 and 15 degrees to avoid severe boundary layer detachment when the fluid exits the throat. This ensures the flow reset effect while minimizing local head loss.

[0072] In this embodiment, refer to Figure 5 The main pipe 61 and the corresponding interface pipe 11, the spiral branch pipe 41 and the corresponding flow reset pipe 7, and the flow reset pipe 7 and the corresponding first pipe 62 or second pipe 63 are all detachably connected by flanges.

[0073] Specifically, refer to Figure 6 The splicing frame 31 contains several layer plates 32, which are arranged at intervals along the vertical direction. The spiral branch pipe 41 includes several rotating pipes 411, which are arranged horizontally and at intervals along the vertical direction. Each rotating pipe 411 corresponds to one of the layer plates 32 and is fixed to the corresponding layer plate 32. The rotating pipes 411 are annular. An interlayer pipe 412 is provided between two adjacent rotating pipes 411. One end of the interlayer pipe 412 is coaxially connected to the outlet end of the adjacent lower rotating pipe 411 and is detachably connected. The other end of the interlayer pipe 412 is coaxially connected to the inlet end of the adjacent upper rotating pipe 411 and is detachably connected.

[0074] For the structural design of the spiral branch pipe 41, the complex three-dimensional spiral structure is decomposed into several layers of planar rotary flow paths through the cooperation of the layer plate 32 and the interlayer pipe 412. This layered structure allows each layer of rotary pipe 411 to be installed, disassembled and maintained independently. When the spiral branch pipe 41 is blocked or the internal components need to be replaced, only the rotary pipe 411 on the specific layer plate 32 needs to be disassembled, without disassembling the entire spiral branch pipe 41.

[0075] In this embodiment, refer to Figure 6 The spiral branch pipe 41 also includes a discharge pipe 413 and a discharge pipe 414. The discharge pipe 414 is coaxially connected to the end of the lowest rotating pipe 411 away from the corresponding interlayer pipe 412 and can be detached. The discharge pipe 413 is coaxially connected to the end of the uppermost rotating pipe 411 away from the corresponding interlayer pipe 412 and can be detached. The discharge pipe 413 and the discharge pipe 414 are coaxially connected to the corresponding flow reset pipe 7 and can be detached.

[0076] With this design, the electrolyte enters from the inlet pipe 414, flows upward through each rotary pipe 411, and finally flows out from the outlet pipe 413. This bottom-up flow method uses buoyancy to naturally expel air bubbles in the pipe and prevents air blockage.

[0077] In this embodiment, refer to Figure 6 and Figure 7 The rotary pipe 411 includes several straight pipes 4111, with no fewer than three straight pipes 4111 located in the same horizontal plane. The straight pipes 4111 are arranged in a ring, and a right-angle pipe 4112 is provided between two adjacent straight pipes 4111. The two ends of the right-angle pipe 4112 are respectively connected to the corresponding straight pipe 4111 and can be detached. This allows the several straight pipes 4111 and the several right-angle pipes 4112 to be connected sequentially. The end of the first straight pipe 4111 that is away from the corresponding right-angle pipe 4112 is coaxially connected to the corresponding interlayer pipe 412 or discharge pipe 413 and can be detached. The end of the last straight pipe 4111 that is away from the corresponding right-angle pipe 4112 is coaxially connected to the corresponding interlayer pipe 412 or discharge pipe 413 and can be detached.

[0078] With the cooperation of several straight tubes 4111 and several right-angle tubes 4112, a ring structure of rotary tube 411 is formed, which allows the electrolyte to flow horizontally over a long distance in each stage, effectively extending the residence time of the electrolyte per unit height. At the same time, the presence of right-angle tubes 4112 causes the fluid to undergo a drastic change of direction at the bend, which enhances radial mixing by utilizing centrifugal force.

[0079] In this embodiment, refer to Figure 7 The detachable connections between the interlayer pipe 412, straight pipe 4111, right-angle pipe 4112, discharge pipe 413, and discharge pipe 414 can all be achieved using socket sealing connections or flange connections. Specifically, when a socket sealing connection is used between two right-angle pipes 4112, the connection structure is generally as follows: a flared socket is provided at the end of the right-angle pipe 4112, the end of the straight pipe 4111 is inserted into the socket, a sealing groove is provided on the inner wall of the socket, and an acid-resistant O-ring is provided in the sealing groove. After the straight pipe 4111 is inserted into the socket, the straight pipe 4111 and the right-angle pipe 4112 are locked and fixed by external clamps or flanges, thereby achieving a socket sealing connection.

[0080] The implementation principle of this application embodiment is as follows: When the electrolyte needs to flow through a certain spiral branch pipe 41, the two first valves 64 corresponding to the spiral branch pipe 41 are opened, and the corresponding second valve 65 is closed at the same time. At this time, the electrolyte is forced into the spiral branch pipe 41 for reaction and propulsion. When it is necessary to skip a certain spiral branch pipe 41, the two corresponding first valves 64 are closed, and the corresponding second valve 65 is opened at the same time. At this time, the electrolyte crosses the corresponding spiral branch pipe 41 and continues to flow upward. This design allows users to instantly adjust the number of spiral branch pipes 41 participating in the circulation without disassembling the hardware, thereby facilitating the maintenance of damaged spiral branch pipes 41 and the adjustment of the effective test volume of the liquid storage device.

[0081] Example 4: A liquid storage device for testing a vanadium redox flow battery stack, referring to... Figure 8 and Figure 9 The difference between this embodiment and embodiment 3 is that: the spiral branch pipe 41 is also provided with an embedded turbulence component 8 and a fluid shaping component 9, and the embedded turbulence component 8 and the fluid shaping component 9 are respectively provided in different straight pipes 4111.

[0082] Reference Figure 8 The embedded turbulence component 8 includes a turbulence hose 81, which is coaxially disposed inside the corresponding straight pipe 4111. The outer diameter of the turbulence hose 81 is smaller than the inner diameter of the corresponding straight pipe 4111, so that the outer wall of the turbulence hose 81 is spaced apart from the inner wall of the corresponding straight pipe 4111, thus forming an annular buffer gap between the outer wall of the turbulence hose 81 and the inner wall of the corresponding straight pipe 4111.

[0083] Reference Figure 8 Both ends of the turbulence hose 81 are sealed to the inner wall of the corresponding straight pipe 4111, which allows the fluid passing through the spiral flow channel 4 to be guided to flow through the inside of the turbulence hose 81.

[0084] Through this sealed connection, the fluid flowing through the straight pipe 4111 is forced to flow entirely into the inner cavity of the turbulence hose 81, allowing the fluid dynamic pressure to effectively act on the inner wall of the turbulence hose 81. As the fluid flows through the turbulence hose 81, the pulsating pressure of the fluid forces the flexible turbulence hose 81 to generate high-frequency micro-amplitude vibrations. These vibrations directly disrupt the laminar boundary layer of the fluid at the pipe wall, eliminating microscopic flow dead zones. This effectively reduces the velocity gradient of the fluid across the pipe cross-section, preventing tailing of the fluid at the pipe wall due to excessively slow flow velocity, and ensuring that the electrolyte propels forward in a flow pattern closer to the ideal flow pattern.

[0085] In this embodiment, refer to Figure 8A support spring 82 is coaxially sleeved on the outer side of the turbulence hose 81. The support spring 82 is located in the annular buffer gap and is spaced apart from the inner side wall of the corresponding straight pipe 4111. The support spring 82 abuts against the outer side wall of the turbulence hose 81, and the two ends of the support spring 82 are respectively fixed to the two ends of the turbulence hose 81.

[0086] With the design of the support spring 82, when the fluid flows through the turbulence hose 81, the turbulence hose 81 will expand radially or vibrate under the action of fluid pulsation pressure. The support spring 82 provides elastic restoring force for the turbulence hose 81, limits the excessive deformation of the turbulence hose 81, and prevents the turbulence hose 81 from sticking to the inner wall of the corresponding straight pipe 4111.

[0087] In this embodiment, refer to Figure 8 It is important to note that the annular buffer gap between the turbulence hose 81 and the inner wall of the straight pipe 4111 is a sealed cavity filled with a compressible medium such as air or nitrogen. This sealed cavity design allows the turbulence hose 81 to elastically expand radially outward when subjected to pulsating pressure from the internal fluid, thereby enhancing the physical disturbance of the fluid boundary layer within the pipe. Furthermore, the support spring 82 not only serves as a connector but also as a radial limiter. When the internal fluid pressure of the turbulence hose 81 increases, the support spring 82 can limit the excessive expansion of the turbulence hose 81, preventing its outer wall from adhering to the inner wall of the straight pipe 4111 and causing vibration failure. The stiffness coefficient of the support spring 82 is matched according to the working fluid pressure range to ensure that the annular buffer gap always exists under normal test pressure.

[0088] In this embodiment, refer to Figure 8 The two ends of the turbulence-disrupting hose 81 are installed into the corresponding straight pipes 4111 via connecting bushings. The connecting bushing includes a bushing body and an extension nozzle. The outer diameter of the bushing body is interference-fitted with the inner diameter of the straight pipe 4111 or fixed to the inside of the port of the straight pipe 4111 by screws. The inner hole of the bushing body serves as a fluid passage. The ends of the turbulence-disrupting hose 81 are fitted onto the extension nozzles and locked with corrosion-resistant hose clamps. When the straight pipe 4111 is inserted into the right-angle pipe 4112, the connecting bushing is limited at the connection step between the straight pipe 4111 and the right-angle pipe 4112, thereby achieving fixation. In another embodiment, the two ends of the turbulence-disrupting hose 81 can also be connected to the two ends of the corresponding straight pipe 4111 via flanges.

[0089] In this embodiment, to ensure that the turbulence-inducing hose 81 is not corroded in the all-vanadium electrolyte environment and can generate effective physical deformation and vibration under fluid scouring, the turbulence-inducing hose 81 is made of a flexible polymer material with acid corrosion resistance and low elastic modulus. Preferably, the turbulence-inducing hose 81 is made of modified polytetrafluoroethylene, soluble polytetrafluoroethylene, or fluororubber. Furthermore, to improve the sensitivity of the turbulence-inducing hose 81 to fluid pulsation, the wall thickness of the turbulence-inducing hose 81 is set to 0.5 mm to 1.5 mm, which allows the turbulence-inducing hose 81 to have good flexibility while ensuring pressure resistance.

[0090] Reference Figure 9 and Figure 10 The fluid shaping assembly 9 includes a shaping flow channel tube 91, which is coaxially disposed within the corresponding straight pipe 4111. The outer wall of the shaping flow channel tube 91 is connected to the inner wall of the corresponding straight pipe 4111, and the shaping flow channel tube 91 is fixed to the corresponding straight pipe 4111. The cross-section of the shaping flow channel tube 91 at its midpoint along its length is elliptical, while the cross-sections at both ends of the shaping flow channel tube 91 are circular.

[0091] With the design of the shaping flow channel 91, when the fluid flows through the shaping flow channel 91, the flow cross section changes from a circle to an ellipse, which forces the streamlines to twist and enhances the lateral flow of the fluid on the cross section. This reorganizes the flow field state, which can break the stable streamline isolation that may be formed when the fluid flows in the circular pipe, and force the fluid particles to be mixed in the entire cross section of the pipe, further eliminating the concentration and temperature differences of the fluid on the macro scale.

[0092] In this embodiment, a plurality of shaping flow channel pipes 91 are provided, and the plurality of shaping flow channel pipes 91 are arranged sequentially at intervals along the length direction of the corresponding spiral branch pipe 41, and the plurality of shaping flow channel pipes 91 are located in different straight pipes 4111 respectively.

[0093] In this embodiment, refer to Figure 7 and Figure 9 The outer diameter of the shaping flow channel tube 91 is interference-fitted with the inner diameter of the corresponding straight tube 4111. During installation, the shaping flow channel tube 91 is pressed into the straight tube 4111 and further secured with acid-resistant adhesive. In another embodiment, positioning flanges are provided at both ends of the shaping flow channel tube 91. When the straight tube 4111 is connected to the right-angle tube 4112, the positioning flanges are clamped and fixed at the connection between the straight tube 4111 and the right-angle tube 4112, thereby achieving axial positioning of the shaping flow channel tube 91.

[0094] The implementation principle of this application embodiment is as follows: When the electrolyte flows within the spiral flow channel 4, it undergoes three different flow field optimization mechanisms: First, when the electrolyte flows through the turbulence hose 81, the fluid flows inside the turbulence hose 81, and the fluid dynamic pressure induces high-frequency vibration of the turbulence hose 81, disturbing the fluid boundary layer at the inner wall of the pipe and reducing the velocity difference between the boundary layer fluid and the main fluid; second, when the electrolyte flows through the right-angle tube 4112, the flow direction changes drastically, and the strong centrifugal force induces Dean vortices on the transverse surface of the fluid, achieving intense stirring and mixing of the fluid in the radial direction; finally, when the electrolyte flows through the shaping flow channel 91, the abrupt change in the shape of the flow cross section promotes radial mixing throughout the entire domain, resetting the flow velocity distribution of the fluid at the macroscopic level. This design ensures that the electrolyte maintains extremely high uniformity and ideal piston flow characteristics during long-distance transportation, thereby guaranteeing that the electrolyte concentration output to the fuel cell stack changes linearly with time, thus improving the accuracy of the fuel cell stack test data.

[0095] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Identical components are represented by the same reference numerals. Therefore, all equivalent changes made to the structure, shape, and principle of this application should be covered within the scope of protection of this application.

Claims

1. A liquid storage device for testing a vanadium redox flow battery stack, characterized in that, include: There are two main manifolds (1), which are spaced apart in the vertical direction; The liquid storage channel mechanism (2) is provided in several parts; the liquid storage channel mechanism (2) includes a support frame (3) and a spiral channel tube (4). The support frame (3) is vertically arranged, and the spiral channel tube (4) is located inside the support frame (3) and connected to the support frame (3). The spiral channel tube (4) is vertically arranged and spirally coiled in the vertical direction. The lower end of the spiral channel tube (4) is connected to one of the main manifolds (1), and the upper end is connected to another main manifold (1). The main manifold (1) located below the spiral channel tube (4) is used to input electrolyte into the spiral channel tube (4), and the other main manifold (1) is used to output electrolyte from the spiral channel tube (4). An embedded turbulence component (8) is provided inside the spiral flow channel tube (4). The embedded turbulence component (8) includes a turbulence hose (81). The turbulence hose (81) is coaxially disposed inside the spiral flow channel tube (4). The outer side wall of the turbulence hose (81) is spaced apart from the inner side wall of the spiral flow channel tube (4). Both ends of the turbulence hose (81) are sealed to the inner side wall of the spiral flow channel tube (4). A support spring (82) is coaxially sleeved on the outside of the turbulence hose (81). The support spring (82) is connected to the turbulence hose (81). The support spring (82) is spaced apart from the inner wall of the spiral flow channel pipe (4). The spiral flow channel (4) is provided with a fluid shaping component (9), which includes a shaping flow channel (91). The shaping flow channel (91) is coaxially arranged inside the spiral flow channel (4). The shaping flow channel (91) is connected to the inner wall of the spiral flow channel (4), and the shaping flow channel (91) has an elliptical cross-section at the middle of its length direction. The support frame (3) includes several splicing frames (31), and the several splicing frames (31) are stacked in sequence along the vertical direction; The spiral flow channel (4) includes a plurality of spiral branch pipes (41), the spiral branch pipes (41) are arranged one-to-one with the splicing frame (31), the spiral branch pipes (41) are located in the corresponding splicing frame (31) and are connected to the splicing frame (31). Several spiral branch pipes (41) are connected in sequence along the vertical direction and are detachably connected. The upper end of the uppermost spiral branch pipe (41) is connected to one of the main conduits (1) and is detachably connected. The lower end of the lowermost spiral branch pipe (41) is connected to another main conduit (1) and is detachably connected. The liquid storage channel mechanism (2) further includes a bridging pipe mesh (6), which includes a main pipe (61), and a first pipe (62) and a second pipe (63) are provided between the spiral branch pipe (41) and the main pipe (61). The main pipe (61) is vertically arranged and located between the two main manifolds (1), and both ends of the main pipe (61) are respectively connected to the two main manifolds (1); Both the first pipe (62) and the second pipe (63) are provided with a first valve (64). One end of the first pipe (62) is connected to the main pipe (61), and the other end is connected to one end of the corresponding spiral branch pipe (41) and is detachably connected. One end of the second pipe (63) is connected to the main pipe (61), and the other end is connected to the other end of the corresponding spiral branch pipe (41) and is detachably connected. The main pipe (61) is provided with a plurality of second valves (65), and the second valves (65) are provided one-to-one with the spiral branch pipe (41). The second valves (65) are located vertically between the connection point of the first pipe (62) and the main pipe (61) and the connection point of the second pipe (63) and the main pipe (61).

2. The liquid storage device for testing a vanadium redox flow battery stack according to claim 1, characterized in that, The main manifold (1) is provided with a plurality of interface pipes (11), which are arranged sequentially along the length of the main manifold (1). The interface pipes (11) are connected to the main manifold (1), and an isolation valve (12) is provided on the interface pipes (11). The isolation valve (12) is used to open or close the corresponding interface pipe (11). The upper end and lower end of the spiral flow channel pipe (4) are respectively connected to the corresponding interface pipe (11).

3. The liquid storage device for testing a vanadium redox flow battery stack according to claim 2, characterized in that, The spiral flow channel (4) is detachably connected to the corresponding interface pipe (11).

4. A liquid storage device for testing a vanadium redox flow battery stack according to claim 2 or 3, characterized in that, The main manifold (1) is provided with a plurality of partition valves (13), which are arranged sequentially at intervals along the length of the main manifold (1), and the plurality of partition valves (13) and the plurality of interface pipes (11) are arranged alternately along the length of the main manifold (1). The partition valves (13) are used to open or close the main manifold (1).

5. The liquid storage device for testing a vanadium redox flow battery stack according to claim 1, characterized in that, A flow reset pipe (7) is provided between the spiral branch pipe (41) and the first pipe (62). One end of the flow reset pipe (7) is connected to the first pipe (62), and the other end is connected to one end of the corresponding spiral branch pipe (41) and can be detachably connected. The inner diameter of the middle part of the flow reset pipe (7) along its own length direction is smaller than the inner diameter of both ends.

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