Hydrogen fuel cell and air compressor inter-stage spiral low-resistance uniform heat exchange device and method

Abstract

The present application relates to a kind of hydrogen fuel cell and air compressor interstage spiral low resistance uniform heat exchange device, including hollow cylinder, and the air duct surrounded by hollow cylinder, the outside of hollow cylinder is cold air flow area, spiral heat exchange flow increasing structure is provided in the air duct inner cavity, for when high temperature and high pressure air passes through air duct, let high temperature and high pressure air can be uniformly heat exchanged in air duct and increase air flow, to effectively reduce the thermal stress inside hydrogen fuel cell, improve output power;The spiral heat exchange flow increasing structure includes at least two adjacent spiral fins, the spiral extension direction of spiral fin is consistent with the flow direction of high temperature and high pressure air;Spiral fin spiral outer edge is fixed on the wall of air duct inner cavity.The present application is designed to meet the actual needs of hydrogen fuel cell and air compressor interstage enhanced heat exchange and flow increasing spiral heat exchange flow increasing structure.

Description

Technical Field

[0001] This invention relates to the field of hydrogen fuel cells, and more particularly to heat exchange structures and methods in hydrogen fuel cells. Background Technology

[0002] Hydrogen, as a renewable energy source, produces only water as a byproduct of its biochemical reaction, making it a crucial technological pathway to achieving pollution-free, zero-emission, and carbon-neutral production. After decades of development, hydrogen-based fuel cell technology now shows broad application prospects in the transportation sector. Major global automotive and aerospace companies are conducting related research, particularly in the automotive industry, where giants like Honda, Toyota, and SAIC have been deeply involved in hydrogen fuel cell vehicles for many years and have achieved partial mass production. In the aviation sector, Rolls-Royce, Airbus, Boeing, the German Aerospace Center (DLR), and NASA have all invested in preliminary research on hydrogen fuel cell aircraft and power systems.

[0003] One of the core components of a hydrogen fuel cell is the fuel cell stack. Hydrogen supplied by a gas source and oxygen-containing air from the environment undergo ion exchange through a proton exchange membrane in the fuel cell stack to achieve voltage output. Similar to how a turbocharger increases the horsepower output of an internal combustion engine by increasing air pressure, a hydrogen fuel cell also needs to pressurize air to meet the power output requirements.

[0004] Generally, the optimal operating pressure for a hydrogen fuel cell stack is 1.3 atmospheres. For automotive hydrogen fuel cells, the air compressor boosting load is relatively low. For aviation applications, due to the thin atmosphere at high altitudes, the air pressure is much lower than at ground level. For example, at an altitude of 20 km, a pressure ratio of 20 is required to boost the air from ambient air to 1.3 atmospheres. On the one hand, there is an urgent need for air compressor designs with extremely high pressure ratios; on the other hand, the high pressure ratio results in high-temperature boosted air that needs efficient cooling before entering the fuel cell for chemical reactions. Therefore, an efficient cooling structure in the air compressor for aviation hydrogen fuel cells is particularly critical.

[0005] The cooling structures currently used are quite complex, with high processing difficulty and cost. They also focus on heat exchange capacity, resulting in generally high flow resistance. This leads to low air pressure and insufficient air flow into the fuel cell, which cannot provide enough pressure and oxygen to the fuel cell stack, thus failing to meet the power output requirements of the hydrogen fuel cell. Furthermore, due to the special nature of the cooling structure, attention must be paid to its processing, and the complexity of the processing inevitably leads to increased costs. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a spiral low-resistance uniform heat exchange device and method between a hydrogen fuel cell and an air compressor stage that can achieve uniform heat exchange between the hydrogen fuel cell and the air compressor stage, increase air flow, and increase the pressure and oxygen quantity at the hydrogen fuel cell stack end.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a spiral low-resistance uniform heat exchange device between a hydrogen fuel cell and an air compressor stage, comprising a hollow cylinder, an air duct inlet and an air duct outlet respectively disposed at both ends of the hollow cylinder, the channel enclosed by the hollow cylinder being an air duct, the outer side of the hollow cylinder being a cold air circulation area, the high-temperature and high-pressure air discharged from the air compressor outlet entering the air duct through the air duct inlet and exchanging heat with the cold air in the cold air circulation area through convection, and finally being discharged to the hydrogen fuel cell stack through the air duct outlet;

[0008] A spiral heat exchange and flow boosting structure is provided in the inner cavity of the air duct to allow the high-temperature and high-pressure air to exchange heat evenly and increase the air flow rate when it passes through the air duct, thereby effectively reducing the thermal stress inside the hydrogen fuel cell and improving the output power.

[0009] The spiral heat exchange and flow boosting structure includes at least two adjacent spiral fins. The spiral fins are spiral curved fins formed by the spiral generatrix moving spirally around the axis of the air duct cavity. The spiral extension direction of the spiral fins is consistent with the flow direction of the high temperature and high pressure air. The spiral outer edge of the spiral fins is fixed to the inner wall of the air duct cavity.

[0010] Furthermore, the helical generatrices of two adjacent helical fins are located on the inscribed circle radius of the hollow cylinder cross-section, the included angle between the helical generatrices is θ, and the number of helical fins is n. Then:

[0011]

[0012] The included angle θ is 20°, 30°, 60°, 72°, 90°, or 180°. The more spiral fins n are provided, the larger the heat exchange area between the high-temperature and high-pressure air and the spiral heat exchange and flow boosting structure will be, and the stronger the heat exchange capacity will be. However, if the angle θ is too small and the number n is too large, the flow resistance will be increased and the flow boosting effect cannot be achieved.

[0013] Meanwhile, the thickness of the spiral fins is δ, and the number of them is n; the diameter of the air duct is D2, and the axial length is L. Therefore, the total weight of the spiral fins is:

[0014]

[0015] That is, under the same mass M, the included angle θ also determines the thickness δ of the spiral fin. The thickness δ is taken as 0.02D2 to 0.15D2. The larger the thickness δ, the stronger the thermal conductivity, which can improve the interstitial heat transfer between the spiral heat exchange boosting structure and the high temperature and high pressure air.

[0016] Furthermore, when the number of spiral fins is greater than three, the included angle θ between the spiral generatrices of any two adjacent spiral fins is the same.

[0017] Furthermore, the number of spiral fins is six, and the included angle θ between the spiral generatrices of two adjacent spiral fins is 60 degrees.

[0018] Furthermore, the pitch P of the spiral fin is used to determine the degree of spirality of the fin. When the axial length of the air duct is L, the pitch P is expressed as:

[0019] P = L / N,

[0020] Wherein, N is the number of rotations of the spiral fins along the axial direction, and N is 1 to 4; as the pitch P decreases, the heat exchange capacity of the heat exchange device gradually increases, but when the pitch P decreases too much, it will also increase the flow resistance and fail to achieve the flow enhancement effect.

[0021] Furthermore, the axial length of the spiral fins is matched with the length of the hollow cylinder.

[0022] Furthermore, the spiral fins have a thickness of 0.11D2-0.2D2 at the inlet of the air duct, the diameter of the air duct is D2, and the thickness decreases to 0.01D2-0.99D2 at the outlet of the air duct. This is used to regulate the axial heat transfer intensity of the air duct, thereby achieving the purpose of improving the overall heat transfer capacity or uniformizing the temperature of the cylinder wall.

[0023] Furthermore, the spiral fin is a continuous spiral curved surface fin formed by the spiral generatrix moving spirally around the axis of the air duct inner cavity.

[0024] Furthermore, the hollow cylinder is cylindrical, the enclosed air duct is a cylindrical hollow duct, and the helical generatrix of the helical fins coincides with and is equal to the cross-sectional radius of the air duct.

[0025] A method for low-resistance uniform heat exchange in a spiral low-resistance uniform heat exchange device between a hydrogen fuel cell and an air compressor stage involves high-temperature, high-pressure airflow impacting the spiral fins of the spiral heat exchange flow-enhancing structure within the air duct. The airflow direction on the spiral fins is deflected, thinning the boundary layer between the high-temperature, high-pressure airflow and the spiral fins, increasing the temperature gradient, and enhancing convective heat exchange. Simultaneously, the deflection of the airflow direction creates radial centrifugal force in the high-temperature, high-pressure air, increasing its velocity near the inner wall of the hollow cylinder, thereby improving heat exchange at the hollow cylinder wall.

[0026] The beneficial effects of this invention are as follows: The fluid inside the cylinder comes from high-temperature, high-pressure air from an air compressor, which is in direct contact with the cylinder. The external airflow is a low-temperature heat exchange flow. A spiral heat exchange and flow boosting structure is provided inside the cylinder duct, resulting in the following beneficial effects:

[0027] I. While meeting the heat exchange requirements, the spiral heat exchange and flow boosting structure provided by this invention has resistance mainly consisting of viscous resistance between the spiral heat exchange and flow boosting structure and high-temperature, high-pressure air, with minimal shape resistance. Therefore, it can reduce flow resistance, thereby increasing the air pressure and flow rate entering the fuel cell, improving oxygen utilization, making the chemical reaction of the hydrogen fuel cell more complete, increasing output power, and enhancing battery power.

[0028] II. The spiral heat exchange and flow boosting structure can effectively reduce the temperature of high-temperature and high-pressure gas by enhancing end-wall heat exchange and interstitial heat exchange, so that the gas temperature can be reduced to below the operating standard of hydrogen fuel cells. This is equivalent to pre-cooling the high-temperature gas and providing thermal protection for the hydrogen fuel cell. Furthermore, due to the unique heat exchange mechanism, the temperature uniformity of the pre-cooled gas is better, which can effectively reduce the internal thermal stress of the hydrogen fuel cell and extend the battery life.

[0029] Third, the spiral heat exchange and flow boosting structure can effectively fix the air duct, giving the air duct extremely high mechanical properties. Furthermore, due to the unique geometry of the structure, the effective bearing area between the spiral heat exchange and flow boosting structure and the cylinder is large, resulting in strong bearing capacity. This enhances its overall performance and improves the lifespan and reliability of the high-temperature and high-pressure air passage between the air compressor and the hydrogen fuel cell.

[0030] Fourth, the spiral heat exchanger flow booster structure is relatively easy to process and can be manufactured by 3D printing, resulting in lower processing costs.

[0031] The spiral heat exchanger and flow booster structure provided by this invention can be parametrically designed. The spiral heat exchanger and flow booster structure can be designed according to requirements. By controlling parameters such as its included angle, thickness, and pitch, the spiral heat exchanger and flow booster structure can be manufactured to meet actual needs. It can even be non-uniformly arranged according to different external environments to enhance local heat exchange. Alternatively, the thickness at the inlet of the spiral heat exchanger and flow booster structure can be increased and the thickness at the outlet can be decreased to regulate the axial heat exchange intensity, thereby achieving the purpose of improving the overall heat exchange capacity or uniformizing the temperature of the cylinder wall.

[0032] Meanwhile, this invention addresses the unique operating environment of high-altitude cruise hydrogen fuel cell-powered aircraft. Leveraging enhanced flow and heat transfer, it organically combines these two aspects by modifying structural features to achieve enhanced heat transfer and reduced flow resistance. Previous designs and solutions for interstage cooling in high-altitude fuel cell air compressors are limited; secondly, the spiral heat exchange flow-enhancing structure is a novel structure, unused in this field; furthermore, research on parametric design of cooling structures in terms of flow and heat transfer is still relatively scarce, with few published documents. Numerical calculations have confirmed that the structure of this invention has a very significant effect on enhanced heat transfer and reduced flow resistance. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the installation location of the present invention;

[0034] Figure 2 This is a schematic diagram of the air duct of the present invention;

[0035] Figure 3 This is a schematic diagram of the air duct with a spiral heat exchange and flow boosting structure embedded in this invention;

[0036] Figure 4 This is a schematic diagram of the spiral fin unit structure of the present invention;

[0037] Figure 5 This is a schematic diagram of the spiral heat exchange and flow boosting structure of the present invention;

[0038] Figure 6 This is a schematic cross-sectional view of the spiral heat exchange and flow boosting structure of the present invention;

[0039] Figure 7 Temperature contour plot of the spiral heat exchanger flow booster structure of this invention (numerical simulation);

[0040] Figure 8 This is a comparison diagram of the flow heat transfer capacity of different cooling structures under experimental conditions according to the present invention;

[0041] Figure 9 This is a temperature cloud diagram of the outlet section under numerical conditions for the spiral heat exchanger flow booster structure of the present invention;

[0042] Figure 10 This diagram illustrates the effect of pitch variation on flow and heat transfer in this invention.

[0043] In the diagram: 1. Hollow cylinder; 2. Air duct; 3. Cold air circulation area; 4. Air duct inlet; 5. Air duct outlet; 6. Spiral fins. Detailed Implementation

[0044] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0045] To achieve the above objectives, the present invention provides the following specific embodiments:

[0046] Example 1: A spiral low-resistance uniform heat exchange device between a hydrogen fuel cell and an air compressor stage includes a hollow cylinder 1, an air duct inlet 4 and an air duct outlet 5 respectively disposed at both ends of the hollow cylinder 1, the channel enclosed by the hollow cylinder 1 is an air duct 2, the outer side of the hollow cylinder 1 is a cold air circulation area 3, the high temperature and high pressure air discharged from the air compressor outlet enters the air duct 2 through the air duct inlet 4 and exchanges heat with the cold air in the cold air circulation area 3 through convection, and finally is discharged to the hydrogen fuel cell stack through the air duct outlet 5;

[0047] A spiral heat exchange and flow boosting structure is provided in the inner cavity of the air duct 2. When the high-temperature and high-pressure air passes through the air duct 2, it can be uniformly heat-exchanged and the air flow rate can be increased in the air duct 2, thereby effectively reducing the thermal stress inside the hydrogen fuel cell and improving the output power.

[0048] The spiral heat exchange and flow boosting structure includes at least two adjacent spiral fins 6. Each spiral fin 6 is a continuous spiral curved surface fin formed by a spiral generatrix moving spirally around the axis of the air duct 2's inner cavity. The spiral extension direction of the spiral fin 6 is consistent with the flow direction of the high-temperature, high-pressure air; the outer spiral edge of the spiral fin 6 is fixed to the inner wall of the air duct 2. The axial length of the spiral fin 6 is matched to the length of the hollow cylinder 1.

[0049] The hollow cylinder 1 is cylindrical, and the enclosed air duct 2 is a cylindrical hollow duct. The helical generatrix of the helical fin 6 coincides with and is equal to the cross-sectional radius of the air duct 2.

[0050] The helical generatrices of two adjacent helical fins 6 are located on the inscribed circle radius of the cross-section of the hollow cylinder 1. When the hollow cylinder 1 is cylindrical, the helical generatrices of two adjacent helical fins 6 are located on the radius of the circular cross-section of the hollow cylinder 1. The included angle between the helical generatrices is θ, and the number of helical fins 6 is n.

[0051]

[0052] The included angle θ can be 20°, 30°, 60°, 72°, 90°, or 180°. The more spiral fins 6 are set, the larger the heat exchange area between the high-temperature and high-pressure air and the spiral heat exchange and flow boosting structure, and the stronger the heat exchange capacity will be. However, if the angle θ is too small and the number n is too large, the flow resistance will be increased and the flow boosting effect cannot be achieved. When the number of spiral fins 6 is greater than three, the included angle θ between the spiral generatrices of two adjacent spiral fins 6 is the same.

[0053] Meanwhile, the thickness of the spiral fins 6 is δ, and the number of them is n; the diameter of the air duct 2 is D2, and the axial length is L. Therefore, the total weight of the spiral fins 6 is:

[0054]

[0055] Under the same mass M, the included angle θ also determines the thickness δ of the spiral fin. The thickness δ can be taken as 0.02D2 to 0.12D2. The larger the thickness δ, the stronger the thermal conductivity, which can improve the interstitial heat transfer between the spiral heat exchange booster structure and the high-temperature and high-pressure air.

[0056] The pitch P of the spiral fin 6 determines the degree of spirality of the fin. When the axial length of the air duct 2 is L, the pitch P is expressed as:

[0057] P = L / N,

[0058] Where N is the number of rotations of the helical fin 6 along the axial direction, and N is 1 to 4; for example Figure 10 As shown, the heat exchange capacity of the heat exchange device gradually increases as the pitch P decreases. However, when the pitch P decreases too much, it will also increase the flow resistance and fail to achieve the flow enhancement effect.

[0059] like Figures 1-6 As shown, a heat exchange and cooling device between a hydrogen fuel cell and an air compressor stage includes a hollow cylinder 1 for connecting the air compressor outlet and the hydrogen fuel cell stack. The hollow cavity of the hollow cylinder 1 forms an air duct 2, and the outer side of the hollow cylinder 1 is a cold air circulation area 3. High-temperature and high-pressure air discharged from the air compressor outlet flows in from the air duct inlet 4, passes through a spiral heat exchange and flow boosting structure in the air duct 2, and flows out from the air duct outlet 5 into the hydrogen fuel cell stack to pressurize the hydrogen fuel cell stack. The high-temperature and high-pressure air undergoes convective heat exchange with the inner wall of the hollow cylinder 1 and the wall surface of the spiral fins 6. The heat load is transferred from the high-temperature and high-pressure air to the cylinder wall and the spiral heat exchange and flow boosting structure, and then dissipates to the outside cold air through convective heat exchange with the cold air circulation area.

[0060] The heat exchange spiral heat exchange booster structure includes at least two adjacent spiral fins 6. The spiral fins 6 are formed by sweeping the fins along the spiral line in the flow direction with the height of the fins having the radius of the air duct 2 as the height. The central axis of the spiral fins 6 coincides with the center line of the inner duct. The number of spiral fins 6 is determined by the included angle θ between the spiral generatrices of the spiral fins 6. The spiral degree of the spiral fins 6 is determined by the pitch P. The pitch refers to the distance that the corresponding point of the spiral fin rotates along the axial direction for one revolution. For example, if the length of the air duct is L, the pitch P = L / 4, that is, the spiral fins rotate four revolutions from the inlet to the outlet.

[0061] The spiral fins 6 and the hollow cylinder 1 together constitute the cooling structure between the air compressor and the hydrogen fuel cell stack: the spiral heat exchange and flow boosting structure 6 is placed along the flow direction, and the parameters of the spiral heat exchange and flow boosting structure are adjusted according to actual needs.

[0062] See Figure 1 , Figure 3 , Figure 5 The high-temperature airflow channel from the air compressor is located on the outside, while the cold airflow area 3 is on the outside. Multiple spiral fins 6 are placed inside the hollow cylinder 1. Each spiral fin 6 is required to be tightly connected to the hollow cylinder 1 and is fixed by surface contact welding. The spiral fins 6 are fixed to the inner wall of the hollow cylinder 1 to form a complete integrated structure.

[0063] Figure 6 A cross-sectional view of the cooling structure is shown. The thickness of the spiral fin unit is δ. As the thickness increases, more heat is transferred to the spiral heat exchange boosting structure, and the interstitial heat transfer of the cooling structure becomes stronger. As the included angle θ decreases, the spiral heat exchange boosting structure will be arranged more densely, which can also enhance the interstitial heat transfer. Figure 5 The diagram also demonstrates the pitch P of the spiral heat exchanger flow booster structure. A smaller pitch P results in a denser spiral heat exchanger flow booster structure and stronger heat exchange capacity. Changes in these three parameters can affect the heat exchange capacity of the cooling structure, but they also alter the flow resistance. Therefore, the specific parameters need to be determined based on actual requirements.

[0064] The spiral heat exchange and flow enhancement structure provided by this invention is generally used between the air compressor and the hydrogen fuel cell reactor of hydrogen fuel cell-powered aircraft used for high-altitude cruising. It replaces the high-pressure air passage after compression by the traditional air compressor. Because of the spiral heat exchange and flow enhancement structure, on the one hand, the spiral surface of the structure forces the fluid to flow along the wall, causing the fluid to flow around the spiral channel, increasing the heat exchange area, enhancing convective heat transfer, and improving cooling efficiency. At the same time, due to the extremely low form resistance, the flow resistance of the channel is greatly reduced. On the other hand, the spiral fin units that are uniformly or non-uniformly distributed circumferentially inside the cylinder enhance the structural performance of the cylinder and effectively extend the service life of the pipeline.

[0065] Example 2: Figure 7 As shown, the embodiment is the same as in Example 1, except that there are six spiral fins 6. The spiral generatrices of the six spiral fins 6 located at the air duct inlet 4 of the hollow cylinder 1 are located on the circular radius of the hollow cylinder 1. At the same time, the included angle θ between the spiral generatrices of two adjacent spiral fins 6 is 60 degrees and they are evenly distributed among each other. The thickness δ of the spiral fin unit is 1.2 mm and the pitch P is 70 mm.

[0066] Figure 7The diagram illustrates the process of a hot fluid being cooled as it passes through a circular tube at a relatively constant wall temperature. It can be seen that, in the direction of the mainstream high-temperature air flow, the spiral heat exchange and flow-enhancing structure within the hollow cylinder 2 effectively reduces the local temperature by mixing with the internal flow structure, ultimately lowering the temperature of the high-temperature air at the outlet. Using this structure, under the given conditions of a mainstream high-temperature gas velocity of 16 m / s and a temperature of 150°C, and an outside cold air temperature of -40°C, the outlet gas temperature was approximately 118°C, and the inlet-outlet pressure difference was 1.14 kPa, achieving enhanced heat transfer while minimizing flow resistance.

[0067] Example 3 is the same as Example 1, except that the thickness of the spiral fins 6 at the inlet of the air duct 2 is 0.11D2-0.2D2, the diameter of the air duct 2 is D2, and the thickness at the outlet of the air duct 2 is reduced to 0.01D2-0.99D2. This is used to regulate the axial heat transfer intensity of the air duct 2, thereby achieving the purpose of improving the overall heat transfer capacity or uniform temperature of the cylinder wall.

[0068] Example 4 is the same as Example 1, except that: the included angle θ between the helical generatrices of two adjacent helical fins 6 is 20°, so the number of helical fins 6 n is 18; the thickness δ is 0.4 mm, the diameter D2 of the air duct 2 is 30 mm, the length of the air duct is L is 280 mm, the total weight M of the hollow cylinder 1 and the helical fins 6 is 82 g, and the material is aluminum.

[0069] Example 5 is the same as Example 1, except that: the included angle between the helical generatrices of two adjacent helical fins 6 is θ, which is 30°; the number of helical fins 6 is n, which is 12; the thickness δ is 0.6 mm; the diameter of the air duct 2 is D2, which is 30 mm; the length of the air duct 2 is L, which is 280 mm; the total weight M of the hollow cylinder 1 and the helical fins 6 is 82 g; and the material is aluminum.

[0070] Example 6 is the same as Example 1, except that the included angle θ between the helical generatrices of two adjacent helical fins 6 is 72°, the number of helical fins 6 n is 5, the thickness δ is 1.44mm, the diameter D2 of the air duct 2 is 30mm, the length of the air duct L is 280mm, the total weight M of the hollow cylinder 1 and the helical fins 6 is 82g, and the material is aluminum.

[0071] Example 7 is the same as Example 1, except that the included angle θ between the helical generatrices of two adjacent helical fins 6 is 90°, the number of helical fins 6 n is 4, the thickness δ is 1.8mm, the diameter D2 of the air duct 2 is 30mm, the length of the air duct L is 280mm, the total weight M of the hollow cylinder 1 and the helical fins 6 is 82g, and the material is aluminum.

[0072] Example 8 is the same as Example 1, except that the included angle θ between the helical generatrices of two adjacent helical fins 6 is 180°, the number of helical fins 6 n is 2, the thickness δ is 3.6 mm, the diameter D2 of the air duct 2 is 30 mm, the length of the air duct L is 280 mm, the total weight M of the hollow cylinder 1 and the helical fins 6 is 82 g, and the material is aluminum.

[0073] Example 9: As Figure 7 As shown, the present invention also provides a heat exchange cooling method for a heat exchange cooling device between a hydrogen fuel cell and an air compressor stage. In the air duct 2, a high-temperature and high-pressure airflow impacts the spiral fins 6 of the spiral heat exchange boosting structure. The airflow direction on the spiral fins 6 is deflected, thinning the boundary layer between the high-temperature and high-pressure airflow and the spiral fins 6, increasing the temperature gradient, and improving convective heat transfer. At the same time, the deflection of the airflow direction causes the high-temperature and high-pressure air to have radial centrifugal force, which increases the flow velocity of the high-temperature and high-pressure air near the inner wall of the hollow cylinder 1, thereby improving the heat transfer of the wall of the hollow cylinder 1.

[0074] In the high-temperature air duct, the high-temperature, high-pressure airflow directly impacts the spiral heat exchange and flow-boosting structure. The airflow direction is deflected and disturbed on the spiral fins, forming a spiral flow. Influenced by the pitch P of the spiral fins 6, the spiral flow deflects towards the inner wall of the hollow cylinder, carrying the internal heat load to the wall. Simultaneously, the high-temperature, high-pressure air also carries away some of the heat load through heat exchange with the wall of the hollow cylinder 1. Meanwhile, the high-temperature, high-pressure air... Figure 7 As can be seen, along the flow direction of the air duct 2 inside the hollow cylinder 1, the compressed air gradually decreases in temperature after encountering the device provided by the present invention, thus effectively and safely pressurizing and cooling the air used in the hydrogen fuel cell stack.

[0075] To accurately determine the heat transfer capacity of the spiral heat exchanger flow booster structure, experimental measurements were conducted on its heat transfer capacity and flow resistance. The experimental setup consisted of a screw air compressor, a Qixing Huachuang mass flow meter, a heater, a test section, and an outlet section connected in sequence. Pressure and temperature measurement points were placed before and after the test section to measure the temperature and pressure changes of the fluid after passing through the cooling structure. The heater maintained a certain power to raise the temperature of the incoming flow in the pipe to 150 degrees Celsius. Then, the high-temperature and high-pressure fluid entered the test section. After pre-cooling by the cooling structure, the fluid pressure drop and temperature drop were measured and finally converted into the Nusselt number, which characterizes the heat transfer capacity, and the Fanning friction factor, which characterizes the flow resistance.

[0076] To demonstrate the advantages of the spiral heat exchanger flow boosting structure in terms of flow heat transfer capacity, experimental studies were conducted on the staggered-angle cross-bend structure and the staggered-angle windward bend structure in patent CN 114156504 A. The results show that the flow heat transfer capacity of the spiral heat exchanger flow boosting structure is 60% stronger than that of the staggered-angle cross-bend structure. Figure 8As shown; and because this structure guides the fluid in a spiral flow, it enables uniform heat exchange, resulting in good temperature uniformity at the channel outlet cross-section, such as... Figure 9 As shown, no hot spots appeared in the temperature cloud map, indicating a significant reduction in thermal stress, which can effectively extend the service life of hydrogen fuel cells.

[0077] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A low-resistance, uniform spiral heat exchange device between a hydrogen fuel cell and an air compressor stage, characterized in that, The hollow cylinder (1) includes an air duct inlet (4) and an air duct outlet (5) respectively located at both ends of the hollow cylinder (1). The channel enclosed by the hollow cylinder (1) is the air duct (2). The outside of the hollow cylinder (1) is the cold air circulation area (3). The high temperature and high pressure air discharged from the air compressor outlet enters the air duct (2) through the air duct inlet (4) and exchanges heat with the cold air in the cold air circulation area (3) through convection. Finally, it is discharged to the hydrogen fuel cell stack through the air duct outlet (5). The hollow cylinder (1) is cylindrical, and the enclosed air duct (2) is a cylindrical hollow duct. The helical generatrix of the helical fin (6) coincides with and is equal to the cross-sectional radius of the air duct (2). A spiral heat exchange and flow boosting structure is provided in the inner cavity of the air duct (2) to allow the high-temperature and high-pressure air to exchange heat evenly and increase the air flow rate when it passes through the air duct (2), thereby effectively reducing the thermal stress inside the hydrogen fuel cell and increasing the output power. The spiral heat exchange and flow boosting structure includes at least two adjacent spiral fins (6). The spiral fins (6) are spiral curved fins formed by the spiral generatrix moving around the inner cavity axis of the air duct (2). The spiral extension direction of the spiral fins (6) is consistent with the flow direction of the high temperature and high pressure air. The outer spiral edge of the spiral fins (6) is fixed to the inner cavity wall of the air duct (2). The pitch P of the spiral fin (6) is used to determine the degree of spiral of the fin. When the axial length of the air duct (2) is L, the pitch P is expressed as: P=L / N, Wherein, N is the number of rotations of the spiral fin (6) along the axial direction, and N is 1~4; as the pitch P decreases, the heat exchange capacity of the heat exchange device gradually increases, but when the pitch P decreases too much, it will also increase the flow resistance and fail to achieve the flow enhancement effect; The spiral fins (6) have a thickness of 0.11 D2-0.2 D2 at the inlet of the air duct (2), and the diameter of the air duct (2) is D2. The thickness of the spiral fins (6) is reduced to 0.01 D2-0.99 D2 at the outlet of the air duct (2). This is used to regulate the axial heat transfer intensity of the air duct (2), thereby achieving the purpose of improving the overall heat transfer capacity or uniform temperature of the cylinder wall.

2. The low-resistance uniform heat exchange device between the hydrogen fuel cell and air compressor stages as described in claim 1, characterized in that, The helical generatrices of two adjacent helical fins (6) are located on the inscribed circle radius of the cross-section of the hollow cylinder (1), the included angle between the helical generatrices is θ, and the number of helical fins (6) is n. Then: ； The included angle θ is 20° or 30° or 60° or 72° or 90° or 180°. The more spiral fins (6) there are, the larger the heat exchange area between the high temperature and high pressure air and the spiral heat exchange and flow boosting structure will be, and the stronger the heat exchange capacity will be. However, when the angle θ is too small and the number n is too large, the flow resistance will be increased and the flow boosting effect cannot be achieved. Under the same mass M, the included angle θ also determines the thickness of the helical fins. Then the thickness Use a thickness of 0.02D2~0.15D2. The larger the diameter, the stronger the thermal conductivity, which in turn enhances the interstitial heat transfer between the spiral heat exchange booster structure and the high-temperature, high-pressure air.

3. The low-resistance uniform heat exchange device between the hydrogen fuel cell and air compressor stages as described in claim 2, characterized in that, When the number of the spiral fins (6) is greater than three, the included angle θ between the spiral generatrices of any two adjacent spiral fins (6) is the same.

4. The low-resistance uniform heat exchange device between the hydrogen fuel cell and air compressor stages as described in claim 2, characterized in that, The number of spiral fins (6) is six, and the angle between the spiral generatrices of two adjacent spiral fins (6) is θ, which is 60 degrees.

5. The low-resistance uniform heat exchange device between the hydrogen fuel cell and air compressor stages as described in claim 1, characterized in that, The axial length of the spiral fin (6) is matched with the length of the hollow cylinder (1).

6. The low-resistance uniform heat exchange device between the hydrogen fuel cell and air compressor stages as described in claim 1, characterized in that, The spiral fin (6) is a continuous spiral curved fin formed by the spiral generatrix moving around the axis of the air duct (2) cavity.

7. A low-resistance uniform heat exchange method for a helical low-resistance uniform heat exchange device between a hydrogen fuel cell and an air compressor stage as described in any one of claims 1-6, characterized in that, In the air duct (2), the high-temperature and high-pressure airflow impacts the spiral fins (6) of the spiral heat exchange and flow enhancement structure. The airflow direction on the spiral fins (6) is deflected, which thins the boundary layer between the high-temperature and high-pressure airflow and the spiral fins (6), increases the temperature gradient, and enhances convective heat transfer. At the same time, the deflection of the airflow direction causes the high-temperature and high-pressure air to have radial centrifugal force, which increases the flow velocity of the high-temperature and high-pressure air near the inner wall of the hollow cylinder (1), thereby enhancing the heat transfer of the wall of the hollow cylinder (1).

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