Plug cone nozzle ejector suitable for hydrogen fuel cell and hydrogen fuel cell system

Abstract

The invention discloses a plug cone nozzle ejector suitable for a hydrogen fuel cell and a hydrogen fuel cell system, and belongs to the technical field of hydrogen fuel cells, and the plug cone nozzle ejector suitable for the hydrogen fuel cell comprises a primary flow inlet pipe, a plug cone nozzle, a mixing chamber and a diffusion chamber which are sequentially communicated along the axis, the suction chamber and the secondary flow inlet pipe are arranged on the side of the plug cone nozzle and are communicated with the mixing chamber; wherein the plug cone nozzle comprises a nozzle structure and a plug cone structure, and the plug cone structure is fixedly arranged on the inner wall of the nozzle structure through a plug cone supporting rod; the outline profile of the plug cone structure sequentially comprises a conical section, a transition section and a bowl-shaped section; wherein the bowl-shaped section is located at one end, close to the primary flow inlet pipe, of the plug cone structure, and the conical section is located at one end, close to the mixing chamber, of the plug cone structure. The stability of the ejector in a variable working condition range is remarkably improved, and a hydrogen supply system formed by the ejector has the characteristics of compact structure and high integration level, and is more suitable for dynamic operation requirements of a hydrogen fuel cell system.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen fuel cell technology, specifically relating to a plug cone nozzle ejector and a hydrogen fuel cell system suitable for hydrogen fuel cells. Background Technology

[0002] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art.

[0003] Proton exchange membrane fuel cells (PEMFCs), as highly efficient energy conversion devices, directly convert the chemical energy of hydrogen into electrical energy through electrochemical reactions. With significant advantages such as high efficiency, rapid start-up, high power density, and low noise operation, they have become a core technology for replacing traditional internal combustion engines and driving the green transformation of automotive power systems. In fuel cell systems, the hydrogen supply subsystem, as a key component, traditionally relies on mechanical pumps to recycle hydrogen and improve hydrogen utilization. However, mechanical pumps have inherent drawbacks such as high cost, insufficient sealing performance, and poor operational stability, and also generate additional parasitic power losses. In contrast, ejectors, with their outstanding characteristics of low cost, zero leakage, low noise, and no parasitic power consumption, show significant potential to replace mechanical pumps and are becoming an important development direction for fuel cell hydrogen supply technology.

[0004] Ejectors, widely used energy conversion devices in fluid machinery, operate on the principle of efficiently transferring and converting kinetic energy through a jet of working fluid. In fuel cell systems, the performance of traditional ejectors is highly dependent on the fuel cell's output power characteristics, with the core evaluation metric being the recirculation rate, the ratio of secondary flow mass flow to primary flow mass flow. Based on the operational requirements of fuel cell systems, a hydrogen excess ratio of greater than 1.5 is typically required, corresponding to a design threshold for the ejector's recirculation rate exceeding 0.5. However, fuel cell vehicles face diverse operating conditions in real-world scenarios, including high-speed cruising, low-speed driving, and idling, placing stringent demands on ejectors to achieve efficient and stable operation across varying operating conditions. Traditional ejectors experience significant performance degradation when deviating from their design operating point, a bottleneck that severely restricts their large-scale application in hydrogen fuel cell systems.

[0005] To address the aforementioned challenges, variable nozzle ejectors can theoretically extend their operating range by dynamically adjusting the nozzle size through a controllable nozzle needle. However, due to the need for high-precision control of the nozzle needle position and reliance on a stable working environment, the complexity of the drive unit structure is significantly increased, making this technology difficult to adapt to the dynamic operation requirements of automotive fuel cell systems. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a plug cone nozzle ejector and hydrogen fuel cell system suitable for hydrogen fuel cells. This not only significantly improves the stability of the ejector in the range of variable operating conditions, but also the hydrogen supply system it constitutes has the characteristics of compact structure and high integration, making it more suitable for the dynamic operation requirements of hydrogen fuel cell systems.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution: In a first aspect, the present invention provides a plug cone nozzle ejector suitable for hydrogen fuel cells, comprising: a primary inlet pipe, a plug cone nozzle, a mixing chamber, and a diffusion chamber connected sequentially along an axis; and an intake chamber and a secondary inlet pipe disposed on the side of the plug cone nozzle and connected to the mixing chamber; wherein the plug cone nozzle includes a nozzle structure and a plug cone structure, the plug cone structure being fixedly disposed on the inner wall of the nozzle structure by a plug cone support rod; the profile of the plug cone structure sequentially includes a conical section, a transition section, and a bowl-shaped section; wherein the bowl-shaped section is located at the end of the plug cone structure near the primary inlet pipe, and the conical section is located at the end of the plug cone structure near the mixing chamber.

[0008] In at least one embodiment, the plug cone support is connected to the transition section of the plug cone structure and extends toward the bowl-shaped section.

[0009] In at least one embodiment, there are two plug cone support rods, arranged symmetrically.

[0010] In at least one embodiment, the plug cone nozzle structure includes a cylindrical section and a tapered section, wherein the portion in the tapered section is conical and the portion in the cylindrical section is cylindrical.

[0011] In at least one embodiment, the mixing chamber includes an isobaric mixing chamber and an isoarea mixing chamber arranged sequentially along the airflow direction.

[0012] In at least one embodiment, the profile of the plug cone structure is designed using the expansion wave method.

[0013] Secondly, the present invention also provides a hydrogen fuel cell system, comprising: a high-pressure hydrogen source, a pressure reducing valve, an ejector, a fuel cell stack, and connecting pipelines; wherein the ejector is a plug cone nozzle ejector as described in the first aspect, suitable for hydrogen fuel cells.

[0014] In at least one embodiment, a proportional valve is provided on the hydrogen supply line leading to the primary inlet pipe of the plug cone nozzle ejector.

[0015] In at least one embodiment, a controller is also included, the controller being configured to adjust the opening of the proportional valve according to the output power of the fuel cell stack.

[0016] In at least one embodiment, a gas-water separator is also included, connected between the anode outlet and the secondary inlet pipe of the fuel cell stack.

[0017] The beneficial effects of the above-described technical solution of the present invention are as follows: 1) The plug cone nozzle ejector of the present invention, applicable to hydrogen fuel cells, forms a plug cone nozzle ejector by fixing the plug cone structure to the inner wall of a traditional nozzle structure. This solves the problem of performance degradation of traditional ejectors under varying operating conditions, effectively reduces energy loss, and broadens the efficient operating range of the ejector. It also expands the operating range of traditional ejectors in fuel cell systems and improves the inherent defect of traditional ejectors in fuel cell systems that cannot adapt to varying operating conditions. In addition, compared with automatic adjustment nozzle ejectors, this design reduces the algorithm complexity of the drive mechanism and control motor, and the hydrogen supply system structure composed of plug cone nozzle ejectors is simpler.

[0018] 2) The plug cone nozzle ejector of the present invention is safe and reliable, simple in structure and low in cost. It has adaptive expansion characteristics and can maintain a near-optimal expansion state under varying operating conditions. This allows the ejector hydrogen cycle system to work under a wide range of fuel cell output power and has excellent performance. Attached Figure Description

[0019] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0020] Figure 1 This is a schematic diagram of a plug cone nozzle ejector suitable for hydrogen fuel cells disclosed in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the existing ejector structure mentioned in Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the plug cone nozzle disclosed in Embodiment 1 of the present invention; Figure 4 This is a schematic diagram of the hydrogen fuel cell system disclosed in Embodiment 2 of the present invention.

[0021] In the picture: 1. Primary inlet pipe; 2. Suction chamber; 3. Single nozzle; 4. Secondary inlet pipe; 5. Isobaric mixing chamber; 6. Isoare mixing chamber; 7. Diffusion chamber; 8. Plug cone nozzle; 9. Conical section; 10. Transition section; 11. Bowl-shaped section; 12. Plug cone support rod. Detailed Implementation

[0022] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0023] As described in the background section, the purpose of this invention is to overcome the shortcomings of the prior art and provide a plug cone nozzle ejector and hydrogen fuel cell system suitable for hydrogen fuel cells. This not only significantly improves the stability of the ejector in the range of varying operating conditions, but also the hydrogen supply system it constitutes has the characteristics of compact structure and high integration, making it more suitable for the dynamic operation requirements of hydrogen fuel cell systems.

[0024] Example 1 like Figure 2 As shown, existing industrial ejectors typically include a primary inlet pipe 1, a suction chamber 2, a single nozzle 3, a secondary inlet pipe 4, a mixing chamber, and a diffusion chamber 7. The mixing chamber comprises an isobaric mixing chamber 5 and an isoarea mixing chamber 6. The single nozzle 3 is connected to the outlet of the primary inlet pipe 1 and passes through the suction chamber 2 into the isobaric mixing chamber 5. The diffusion chamber 7 is connected to the outlet of the isoarea mixing chamber 6. The secondary inlet pipe 4 is positioned below the suction chamber 2 and flows into the isobaric mixing chamber 5. The working process is as follows: high-pressure hydrogen gas, after passing through a pressure reducing valve and a proportional valve, obtains a suitable hydrogen supply pressure. It then passes through the primary single nozzle 3, forming a low-pressure region at the nozzle outlet. This low-pressure region can draw in hydrogen, water vapor, and nitrogen from the anode outlet of the fuel cell stack. The two gases then exchange energy in the mixing chamber, and finally, the mixed gas is sent to the fuel cell stack. However, the performance of this ejector significantly degrades when deviating from its design operating point. This bottleneck severely restricts its large-scale application in hydrogen fuel cell systems.

[0025] To overcome the shortcomings of the prior art, in a typical embodiment of the present invention, such as... Figure 1 As shown, this embodiment discloses a plug cone nozzle ejector suitable for hydrogen fuel cells, including: a primary inlet pipe 1, a plug cone nozzle 8, a mixing chamber and a diffusion chamber 7 connected sequentially along an axis, and an intake chamber 2 and a secondary inlet pipe 4 disposed on the side of the plug cone nozzle 8 and connected to the mixing chamber; the primary inlet pipe 1 is used to receive high-pressure hydrogen gas after depressurization, and expands at the outlet of the plug cone nozzle 8 to form a low-pressure area to draw in the gas at the anode outlet of the fuel cell connected to the secondary inlet pipe 4, and then mixes it in the mixing chamber before sending it into the fuel cell stack.

[0026] In this embodiment, the plug cone nozzle 8 includes a nozzle structure and a plug cone structure, which is fixedly mounted on the inner wall of the nozzle structure by a plug cone support rod 12.

[0027] In this embodiment, the profile of the plug cone structure is designed using the expansion wave method according to the requirements of a hydrogen fuel cell. Specifically, the primary flow inlet mass flow rate of the ejector is:

[0028] In the formula, Rated power of hydrogen fuel cells; This refers to the molar mass of hydrogen gas. This refers to the voltage of a single fuel cell. is Faraday's constant.

[0029] The throat area is the minimum area of ​​the flow cross-section formed by the plug cone and the nozzle, specifically expressed as:

[0030] In the formula, The mass flow rate at the primary inlet of the ejector; The specific heat ratio of hydrogen; The gas constant for hydrogen; This is the critical temperature of hydrogen. Design pressure for the primary flow inlet pipe of the ejector.

[0031] The nozzle exit design Mach number is specifically expressed as follows:

[0032] In the formula, The specific heat ratio of hydrogen; Design pressure for the primary flow inlet pipe of the ejector; Design pressure for ejector outlet.

[0033] The cone angle of the conical segment of the plug cone is expressed as:

[0034] Therefore, the relationship between the height of the cone-shaped section and the diameter of the cup-shaped section is specifically expressed as follows:

[0035] In the formula, The height of the cone-shaped section of the plug cone; The diameter of the bowl-shaped section.

[0036] Based on the height of the cone segment , diameter of the bowl section and throat area Through iterative calculations, the plug cone structure was finally determined.

[0037] like Figure 3As shown, the profile of the plug cone structure sequentially includes a conical section 9, a transition section 10, and a bowl-shaped section 11. The bowl-shaped section 11 is located at the end of the plug cone structure near the primary inlet pipe 1, while the conical section 9 is located at the end near the mixing chamber. The conical surface of the conical section 9 guides the airflow, allowing it to smoothly adhere to the wall surface, reducing flow separation, and achieving stable fluid flow and pressure recovery. The transition section 10 then connects the conical section and the bowl-shaped section, ensuring smooth airflow from the bowl-shaped section to the conical section and preventing abrupt changes or separation. Finally, the bowl-shaped section 11 compresses the working fluid, promoting airflow acceleration while ensuring uniform velocity distribution. After the high-pressure working fluid is accelerated to supersonic speed by the plug cone nozzle, it enters the relatively spacious suction chamber from the nozzle outlet. The reduced velocity causes a sharp drop in static pressure, creating a low-pressure zone.

[0038] As a further embodiment, the plug cone support rod 12 is connected to the transition section 10 of the plug cone structure and extends towards the bowl-shaped section 11, thereby fixing the plug cone to the inner wall of the nozzle. The specifications and dimensions of the plug cone support rod 12 are determined according to the actual situation to ensure that the plug cone structure is fixed to the inner wall of the nozzle.

[0039] As a further embodiment, the number of plug cone support rods 12 is at least two, and they are arranged symmetrically.

[0040] In this embodiment, the nozzle structure of the plug cone includes a cylindrical section and a tapered section. The tapered section is conical, and the cylindrical section is cylindrical. The cylindrical section of the nozzle structure is connected to the hydrogen supply pipeline through the primary inlet pipe 1, receiving the depressurized high-pressure hydrogen gas supplied through the primary inlet pipe. The tapered section of the nozzle structure traverses the suction chamber 2, and its nozzle outlet enters the isobaric mixing chamber, thereby creating a low-pressure area at the nozzle outlet.

[0041] In this embodiment, the mixing chamber includes an isobaric mixing chamber 5 and an equal-area mixing chamber 6 arranged sequentially along the airflow direction. The isobaric mixing chamber 5 ensures that the pressure of the primary and secondary fluids gradually equalizes during mixing, preventing energy loss or flow separation due to excessive pressure difference. The equal-area mixing chamber 6 forces the two fluids to mix thoroughly through a fixed cross-sectional area, achieving homogenization of the velocity and temperature fields through turbulent exchange. The mixing chamber's design, combining isobaric and equal-area mixing, facilitates sufficient energy exchange while minimizing pressure loss.

[0042] In this embodiment, the diffusion chamber 7 receives the gas mixed in the mixing chamber and converts the kinetic energy of the mixed gas into pressure energy to increase its pressure level. When the pressure reaches the hydrogen supply pressure required by the fuel cell stack, the mixed gas is sent into the fuel cell stack.

[0043] The working process of the plug cone nozzle 8 ejector in this embodiment is as follows: During the operation of the fuel cell stack, high-pressure hydrogen is depressurized and enters the plug cone nozzle 8 through the primary inlet pipe 1. After the high-pressure working fluid is accelerated to supersonic speed through the plug cone nozzle, it enters the relatively spacious intake chamber from the nozzle outlet. The flow velocity decreases, causing the static pressure to drop sharply. This results in expansion at the nozzle outlet, forming a low-pressure area. This low-pressure area is lower than the pressure of the secondary hydrogen, which can be drawn into the intake chamber 2 through the secondary inlet pipe 4. The two gas streams are mixed at the same pressure and area in the mixing chamber before entering the diffusion chamber. When the mixed gas enters the diffusion chamber, the velocity decreases, accompanied by an increase in pressure, reaching the hydrogen supply pressure required by the fuel cell stack. Finally, it enters the fuel cell stack from the plug cone ejector outlet.

[0044] The geometry of the plug cone nozzle 8 in this embodiment is designed to create a continuous expansion wave on the surface of the plug cone by precisely calculating the angle between the Mach line and the axis. When the external pressure changes, the distribution of the expansion wave automatically adjusts to ensure that the airflow always expands smoothly along the profile, avoiding separation or under-expansion. Simultaneously, the plug cone nozzle combines the internal expansion of the nozzle channel and the external expansion of the plug cone's conical section. Under varying operating conditions, internal expansion stabilizes the core flow field, while external expansion adapts to changes in environmental pressure. These two mechanisms work together to achieve adaptive regulation; for example, external expansion dominates under high pressure, while internal expansion is enhanced under low pressure. Furthermore, the plug cone profile optimizes the airflow deflection angle and Mach number distribution, reducing shock wave losses. Even with changes in external pressure, the airflow can maintain a near-optimal expansion state through expansion wave reorganization, resulting in significantly higher efficiency than traditional nozzles. Based on this, the plug cone nozzle achieves highly efficient and stable performance under varying operating conditions through geometric adaptation, dynamic adjustment of the expansion wave, and synergy between the internal and external flow fields. It possesses adaptive expansion characteristics and can maintain a near-optimal expansion state under varying operating conditions. When the operating conditions of the fuel cell system change significantly, the adaptive expansion characteristics of the plug cone nozzle 8 allow the ejector to operate under a wide range of fuel cell output power and maintain excellent performance, effectively solving the problem of performance fluctuation of the traditional single nozzle 3 ejector under varying operating conditions.

[0045] Example 2 In a typical embodiment of the present invention, such as Figure 4 As shown, this embodiment discloses a hydrogen fuel cell system, including: a high-pressure hydrogen source, a pressure reducing valve, an ejector, a fuel cell stack, and connecting pipelines; wherein, the ejector adopts the plug cone nozzle 8 ejector suitable for hydrogen fuel cells as described in Embodiment 1.

[0046] In this embodiment, a proportional valve is provided on the hydrogen supply line of the primary inlet pipe 1 leading to the ejector of the plug cone nozzle 8, and the pressure of hydrogen entering the ejector of the plug cone nozzle 8 is controlled by controlling the opening degree of the proportional valve.

[0047] As a further embodiment, the hydrogen fuel cell system also includes a controller configured to adjust the opening of a proportional valve according to the output power of the fuel cell stack.

[0048] As a further embodiment, the hydrogen fuel cell system also includes a gas-water separator connected between the anode outlet of the fuel cell stack and the secondary flow inlet pipe 4, for removing liquid water from the unreacted hydrogen mixture (rich in hydrogen, water vapor and a small amount of nitrogen, etc.) discharged from the anode of the fuel cell stack to obtain secondary flow gas.

[0049] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A plug-cone nozzle ejector suitable for use in a hydrogen fuel cell, characterised in that, The application relates to a plug-cone nozzle ejector suitable for hydrogen fuel cells. The plug-cone nozzle ejector comprises a primary flow inlet pipe, a plug-cone nozzle, a mixing chamber and a diffusion chamber which are sequentially communicated along an axis, and a suction chamber and a secondary flow inlet pipe which are arranged at the side of the plug-cone nozzle and are communicated with the mixing chamber; wherein the plug-cone nozzle comprises a nozzle structure and a plug-cone structure, the plug-cone structure is fixedly arranged on the inner wall of the nozzle structure through plug-cone supporting rods, the profile surface of the plug-cone structure comprises a conical section, a transition section and a bowl-shaped section in sequence, the bowl-shaped section is located at one end of the plug-cone structure close to the primary flow inlet pipe, and the conical section is located at one end of the plug-cone structure close to the mixing chamber.

2. The plug-cone nozzle ejector suitable for a hydrogen fuel cell of claim 1, wherein, The plug-cone supporting rods are connected to the transition section of the plug-cone structure and extend to the bowl-shaped section.

3. The plug-cone nozzle ejector suitable for a hydrogen fuel cell of claim 1, wherein, The number of the plug-cone supporting rods is two, and the plug-cone supporting rods are symmetrically arranged.

4. The plug-cone nozzle ejector suitable for a hydrogen fuel cell of claim 1, wherein, The nozzle structure of the plug-cone nozzle comprises a cylindrical section and a tapered section, the part in the tapered section is conical, and the part in the cylindrical section is cylindrical.

5. The plug-cone nozzle ejector suitable for a hydrogen fuel cell of claim 1, wherein, The mixing chamber comprises an isobaric mixing chamber and an isometric mixing chamber which are sequentially arranged along the airflow direction.

6. The plug-cone nozzle ejector suitable for a hydrogen fuel cell of claim 1, wherein, The profile surface of the plug-cone structure is designed by using an expansion wave method.

7. A hydrogen fuel cell system characterized by comprising: The application relates to a hydrogen fuel cell system. A proportional valve is arranged on the hydrogen supply pipeline of the primary flow inlet pipe of the plug-cone nozzle ejector.

8. A hydrogen fuel cell system as claimed in claim 7, wherein, The system further comprises a controller which is configured to adjust the opening degree of the proportional valve according to the output power of the fuel cell stack.

9. A hydrogen fuel cell system as claimed in claim 8, wherein, The system further comprises a steam-water separator which is connected between the anode outlet of the fuel cell stack and the secondary flow inlet pipe.

10. A hydrogen fuel cell system as in claim 7, wherein, ​

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