A composite heat dissipation hydrogen fuel stack based on boundary layer management

Abstract

The application provides a composite heat dissipation hydrogen fuel cell stack based on boundary layer management, and relates to the technical field of batteries. The stack comprises two end plates and a plurality of current collectors stacked between the two end plates. The current collectors comprise, in the stacking direction, a cathode, a first bipolar plate, a membrane electrode, a second bipolar plate, an anode and a separator in sequence. Mounting holes are formed in the end plates and the current collectors, and bolts are inserted into the mounting holes to connect the current collectors and the end plates. The stack further comprises a heat sink and a fan. The fan drives airflow through the air gap of the current collectors and then through the heat sink. The heat sink comprises two symmetrical heat dissipation frames. Each heat dissipation frame comprises a partition plate and heat dissipation fins located on the outer side of the partition plate. Adjacent heat dissipation fins have a spacing therebetween. The side walls of the heat dissipation fins are provided with a plurality of turbulence protrusions. The middle part of the partition plate is recessed inwardly. The edge sides of the partition plate close to the two end plates are respectively provided with a separation step. The separation step is a negative pressure notch recessed inwardly of the partition plate. The application has the advantages of good heat dissipation effect and the like.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more particularly to a composite heat-dissipating hydrogen fuel cell stack based on boundary layer management. Background Technology

[0002] Hydrogen fuel cells, as the core device for the efficient conversion and utilization of hydrogen energy, have been rapidly promoted in recent years in fields such as vehicle power and distributed power generation due to their significant advantages of high energy conversion efficiency and zero carbon emissions. Among them, forced air-cooled hydrogen fuel cell stacks have become the mainstream choice for small and medium power portable hydrogen energy scenarios due to their simple system structure, low operation and maintenance costs, and strong environmental adaptability.

[0003] Current conventional forced-air-cooled hydrogen fuel cell stacks typically employ flat, smooth, one-piece metal heat sinks as the core heat exchange component. During high-speed airflow within the channels formed by these heat sinks, a flow boundary layer inevitably forms near the wall of the heat sink. This boundary layer thickness continuously increases along the airflow direction, and airflow separation can easily occur at abrupt expansion points in the flow channel cross-section. These boundary layer issues significantly increase the local thermal resistance near the wall, ultimately resulting in a low overall convective heat transfer efficiency for the heat sink. This leads to uneven temperature distribution and localized overheating during long-term operation, which can reduce the stack's energy conversion efficiency or accelerate the aging and degradation of the membrane electrode assembly (MEA), drastically shortening the stack's overall lifespan. Furthermore, in low-temperature environments, condensation and water accumulation within the flow channels, as well as blockages in the gas passages, are common problems, severely restricting the operational stability and environmental adaptability of air-cooled hydrogen fuel cell stacks.

[0004] Currently, most optimization solutions in the industry only improve the heat dissipation effect by simply increasing fan power and increasing the density of heat sinks. However, such improvements will significantly increase the flow resistance of the system and increase the power consumption of the fan, which will offset the effective output efficiency of the fuel cell stack. They have never systematically solved the bottleneck problem of heat exchange efficiency of air cooling from the root cause of boundary layer flow characteristics. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention proposes a hydrogen fuel cell stack structure that can improve heat dissipation efficiency.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a composite heat dissipation hydrogen fuel cell stack based on boundary layer management, the stack comprising two end plates and a plurality of current collectors stacked between the two end plates, the current collectors comprising, in the stacking direction, a cathode, a first bipolar plate, a membrane electrode, a second bipolar plate, an anode, and a diaphragm, wherein through-hole mounting holes are provided on the end plates and the current collectors, and bolts are inserted into the mounting holes to connect the current collectors to the end plates; characterized in that it further comprises a radiator and a fan, the fan driving airflow through the air gap of the current collectors and then through the radiator, the radiator comprising two symmetrically distributed heat sinks, the heat sinks comprising partition plates and heat sink fins located outside the partition plates, with a gap between adjacent heat sink fins, the sidewalls of the heat sink fins having several interference flow protrusions, the middle of the partition plate being recessed inward, and the partition plate having a separation step on each side near the two end plates, the separation step being a negative pressure notch recessed inward towards the partition plate.

[0007] Furthermore, the surface of the heat sink is densely covered with several turbulence-disrupting notches, and each turbulence-disrupting notch forms a pit array on the surface of the heat sink.

[0008] Furthermore, the turbulence protrusion is wedge-shaped, with the smaller end of the turbulence protrusion facing the surface of the heat sink adjacent to the heat sink.

[0009] Compared with the prior art, the present invention has the following advantages: 1. The turbulence protrusions in the airflow path are equivalent to vortex generators that can generate flow vortices, continuously displacing the hot air near the wall and injecting kinetic energy into the boundary layer, effectively delaying its separation and keeping the heat sink in high-efficiency heat exchange along its entire length. 2. The pit array forms constrained micro-vortices within the pits, continuously disturbing the boundary layer without significantly increasing flow resistance, enhancing local turbulence intensity, and making the heat transfer process more uniform and efficient. 3. The separation step forces the airflow to separate at a fixed point at the sudden expansion of the flow channel section, and forms a stable backflow vortex, which guides the mainstream to quickly reattach to the downstream surface, transforming the original harmful separation zone into an enhanced heat transfer zone. The three structures mentioned above work together to systematically enhance convective heat transfer from three levels: delayed separation, continuous disturbance, and controlled reattachment, thereby improving the conversion efficiency and operational reliability of the fuel cell stack. Attached Figure Description

[0010] Figure 1 This is a three-dimensional structural diagram of the fuel cell stack.

[0011] Figure 2 This is a side view of the fuel cell stack (the arrows indicate the side airflow paths).

[0012] Figure 3 for Figure 1 A magnified view of part A in the middle.

[0013] Legend: 1. Cathode; 2. First bipolar plate; 3. Membrane electrode; 4. Second bipolar plate; 5. Anode; 6. Diaphragm; 7. Partition plate; 8. Heat sink; 9. Turbulence protrusion; 10. Separation step; 11. End plate. Detailed Implementation

[0014] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings to further illustrate the technical solutions of the present invention. However, the present invention is not limited to these embodiments.

[0015] like Figures 1 to 3 As shown, the fuel cell stack consists of end plates 11, insulating gaskets, and collectors on both the front and rear sides. Internally, a cathode 1, a first bipolar plate 2, a membrane electrode 3, a second bipolar plate 4, an anode 5, and a diaphragm 6 are arranged sequentially. Each component has two holes along its diagonal, and the entire assembly is fastened together with bolts and nuts. The right end plate 11 has threaded holes for securing the right-side fan with screws. The insulating gasket is attached to the inside of the end plate 11, engaging with the collector to prevent the end plate 11 from becoming energized. A fan is installed on the side of the fuel cell stack closest to the heat sink.

[0016] After hydrogen is introduced into the fuel cell stack, an electrochemical reaction occurs at anode 5, producing carbon dioxide and water vapor. Simultaneously, electrons are transferred from anode 5 to cathode 1, forming an electric current, which raises the stack temperature. A fan creates negative pressure, drawing airflow into the stack, bringing in oxygen and driving the carbon dioxide and water vapor to the left. Heat is conducted to the heat sink 8 via the bipolar plates.

[0017] The surface of the heat sink 8 features integrally formed turbulence protrusions 9, forming a vortex generator consisting of paired, tilted small triangular fins (i.e., wedge-shaped). As airflow passes through, it generates directional vortices, drawing cool air towards the surface of the heat sink 8, replacing the hot air near the wall and delaying boundary layer separation. The surface of the heat sink 8 also features an array of pits, i.e., inwardly concave ellipsoidal crown-shaped microstructures. As airflow passes through, constrained microvortices are formed within these pits, continuously disturbing the boundary layer without significantly increasing flow resistance. A separation step 10 is provided within the airflow channel between adjacent heat sinks 8. This step is located at a sudden widening of the channel cross-section and is a stepped bend extending longitudinally. As airflow passes through, the step forces the airflow to separate at a fixed point, forming a stable backflow vortex on the leeward side, guiding the mainstream to quickly reattach to the downstream heat sink 8 surface. A fan on the left side of the fuel cell stack draws air outward, creating a pressure differential to accelerate heat dissipation.

[0018] The eddy current generator, pit array, and separation step 10 work together to enhance convective heat transfer, effectively solving the problems of excessively high stack temperature and low-temperature condensation, and providing a reliable design scheme for hydrogen fuel cell stacks with high adaptability and high conversion rate.

[0019] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A composite heat dissipation hydrogen fuel cell stack based on boundary layer management, the stack comprising two end plates (11) and a plurality of current collectors stacked between the two end plates (11), wherein the current collectors, in the stacking direction, sequentially comprise a cathode (1), a first bipolar plate (2), a membrane electrode (3), a second bipolar plate (4), an anode (5), and a diaphragm (6), wherein through mounting holes are provided on the end plates (11) and the current collectors, and bolts are inserted into the mounting holes to connect the current collectors to the end plates (11); characterized in that, It also includes a heat sink and a fan, the fan driving airflow through the air gap of the collector and then through the heat sink, the heat sink including two symmetrically distributed heat sinks, the heat sink including a partition plate (7) and heat sink fins (8) located outside the partition plate (7), there is a gap between adjacent heat sink fins (8), the sidewall of the heat sink fins (8) has a few interference flow protrusions (9), the middle part of the partition plate (7) is recessed inward, the partition plate (7) has a separation step (10) on the side of the two end plates (11) respectively, the separation step (10) is a negative pressure notch recessed inward towards the partition plate (7).

2. The composite heat dissipation hydrogen fuel cell stack based on boundary layer management according to claim 1, characterized in that, The surface of the heat sink (8) is densely covered with several turbulence flow notches, and each turbulence flow notch forms a pit array on the surface of the heat sink (8).

3. The composite heat dissipation hydrogen fuel cell stack based on boundary layer management according to claim 1, characterized in that, The turbulence protrusion (9) is wedge-shaped, with the small end of the turbulence protrusion (9) facing the surface of the heat sink adjacent to the heat sink.

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