Combination nozzle ejector for hydrogen fuel cell

Abstract

The invention relates to the field of ejectors and hydrogen fuel cells, in particular to a combined nozzle ejector for a hydrogen fuel cell, which comprises a body, and a suction chamber, an isobaric mixing cavity, an equal-area mixing cavity and a diffusion chamber are sequentially arranged in the body along the axis; and the suction chamber is communicated with the first flow pipe. The hydrogen discharged from the fuel cell anode can be fully absorbed according to different power of the fuel cell, the output voltage of the cell is ensured, and the electrochemical reaction rate is stabilized.

Description

Technical Field

[0001] The invention of the present application relates to the fields of ejectors and hydrogen fuel cells, and particularly to a combined nozzle ejector for hydrogen fuel cells. Background Art

[0002] When a proton exchange membrane fuel cell operates, in order to improve the cell performance, usually an excessive amount of hydrogen is supplied to the anode of the fuel cell stack. On the one hand, the excessive hydrogen can be used to purge and remove the water generated inside the fuel cell stack and permeated to the anode. On the other hand, the concentration of the tail gas hydrogen can be reduced, and the hydrogen utilization rate can be improved. Therefore, the hydrogen supply system of the proton exchange membrane fuel cell mainly adopts a recirculation mode. An ejector is a commonly used recirculation device. It has the advantages of simple structure, small volume, no parasitic power, low cost, low noise, good sealing performance, etc. Therefore, the ejector has great research potential as a recirculation device in the hydrogen recirculation system of the proton exchange membrane fuel cell.

[0003] An ejector is a device that utilizes the Venturi effect to eject a high-speed and high-energy flow to entrain another low-speed and low-energy flow, thereby achieving energy conversion. During the operation of a proton exchange membrane fuel cell stack, usually an excessive amount of hydrogen needs to be introduced. Conversely, the hydrogen supply system of the proton exchange membrane fuel cell will be in a reflux state and cannot operate normally. Traditional ejectors rely on means such as multiple nozzles or increasing the ejector flow rate to prompt the timely discharge of the hydrogen generated at the anode of the fuel cell. However, during the operation of the fuel cell, according to the different powers, the required hydrogen amount is different. When the negative pressure generated by the ejector flow is insufficient to timely discharge the hydrogen generated at the anode of the fuel cell at high power or when the power changes, according to the Nernst equation, the electromotive potential of the battery will decrease, resulting in a decrease in the battery output voltage. Moreover, too much hydrogen occupies the reaction sites, hindering new hydrogen molecules from reaching the catalyst surface for oxidation reaction, thereby reducing the electro-chemical reaction rate; while increasing the ejector flow rate will cause uneven mixing of the low-speed and low-energy hydrogen flow. Summary of the Invention

[0004] In view of the above problems, the present invention proposes a combined nozzle ejector for hydrogen fuel cells, including a body. An inhalation chamber, an isobaric mixing chamber, an equal-area mixing chamber and a diffusion chamber are sequentially arranged along the axis inside the body; the inhalation chamber is communicated with a first flow tube, and a first branch is arranged on the side wall of the first flow tube; a spraying structure is detachably installed at the side end of the body. The spraying mechanism includes a second flow tube, a third flow tube and a fourth flow tube arranged in sequence along the axis. The fourth flow tube is communicated with the first branch. A first nozzle and a second nozzle are respectively arranged at the ends of the second flow tube and the third flow tube, and the first nozzle and the second nozzle are overlapped. The third nozzle at the end of the fourth flow tube is located in front of the first nozzle, and when the first nozzle or the second nozzle operates, a negative pressure is formed at the port of the third nozzle.

[0005] Preferably, the inlet end of the second flow tube is perpendicular to the body, and its outlet end is in a tapered structure that gradually narrows along the axis of the body. The inlet end of the third flow tube is perpendicular to the body, and its outlet end is sleeved outside the second flow tube and is in a tapered structure that gradually narrows along the axis of the body. The inlet end of the fourth flow tube is perpendicular to the body, and its outlet end is arranged outside the third flow tube and is in a tapered structure that gradually narrows along the axis of the body.

[0006] Preferably, the second flow tube is composed of an end cap detachably installed on the body and a first tapered structure; the third flow tube is composed of a first tapered structure and a second tapered structure detachably installed on the body; the fourth flow tube is composed of a second tapered structure and a third tapered structure detachably installed on the body.

[0007] Preferably, the diameter of the first nozzle is smaller than that of the second nozzle, and the diameter of the second nozzle is smaller than that of the third nozzle.

[0008] Preferably, the second flow tube and the third flow tube respectively receive hydrogen after being decompressed by a pressure reducing valve; the first flow tube receives hydrogen at the anode outlet of the hydrogen fuel cell stack.

[0009] Preferably, the first flow tube includes a second branch, and the second branch connects the first flow tube to the inlet end of the suction chamber in a staggered manner.

[0010] Preferably, a third branch is provided inside the body. The third branch connects the third flow tube and the second branch, and a fourth nozzle is provided at the connection between the second branch and the third flow tube. When the third flow tube is connected to the gas, the fourth nozzle can accelerate the flow of the first flow tube.

[0011] The beneficial effects of this application are as follows: This application can fully absorb the hydrogen discharged from the anode of the fuel cell according to the different powers of the fuel cell, ensure the output voltage of the battery, and stabilize the electro-chemical reaction rate. Description of the Drawings

[0012] Figure 1 is an exploded view of the structure of the combined nozzle ejector for a hydrogen fuel cell according to Embodiment 1 of the present invention; Figure 2 is a schematic diagram of the structure of the combined nozzle ejector for a hydrogen fuel cell according to Embodiment 1 of the present invention; Figure 3 is a schematic diagram of the structure of the combined nozzle ejector for a hydrogen fuel cell according to Embodiment 2 of the present invention.

[0013] 1. Body; 2. Suction chamber; 3. Isobaric mixing chamber; 4. Equal-area mixing chamber; 5. Diffusion chamber; 6. First flow tube; 6-1. First branch; 7. Second flow tube; 8. Third flow tube; 9. Fourth flow tube; 10. First nozzle; 11. Second nozzle; 12. Third nozzle; 13. End cap; 14. First conical structure; 15. Second conical structure; 16. Third conical structure; 17. Third branch; 18. Fourth nozzle. Detailed implementation mode

[0014] The present application will be further described below in conjunction with the accompanying drawings and embodiments.

[0015] It should be noted that the following detailed descriptions are all illustrative and are intended to provide further explanations for the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0016] Example 1, as Figures 1 to 2 shown, a combined nozzle ejector for a hydrogen fuel cell includes a body 1. Inside the body 1, a suction chamber 2, an isobaric mixing chamber 3, an equal-area mixing chamber 4, and a diffusion chamber 5 are sequentially arranged along the axis; the suction chamber 2 is connected to a first flow tube 6, and a first branch 6-1 is provided on the side wall of the first flow tube 6, and a blocking switch is provided inside the first branch 6-1; a spraying structure is detachably installed on the side end of the body 1. The spraying mechanism includes a second flow tube 7, a third flow tube 8, and a fourth flow tube 9 sequentially arranged along the axis. The fourth flow tube 9 is connected to the first branch 6-1. A circular first nozzle 10 and an annular second nozzle 11 are respectively provided at the ends of the second flow tube 7 and the third flow tube 8, and the first nozzle 10 and the second nozzle 11 are overlapped, that is, the second nozzle 11 is sleeved outside the first nozzle 10. The third nozzle 12 at the end of the fourth flow tube 9 is located in front of the first nozzle 10, and when the first nozzle 10 or the second nozzle 11 operates, a negative pressure is formed at the port of the third nozzle 12. It should be further pointed out that the fluid is smoothly converted between the chambers through a transition structure. The suction chamber 2 is connected to an external gas source through the first flow tube 6. A first branch 6-1 is provided on the side wall of the first flow tube 6, and a precisely controllable blocking switch is provided inside the first branch 6-1 for adjusting the on / off and flow rate of the air flow. A spraying structure is detachably installed on the side end of the body 1. The spraying mechanism includes a second flow tube 7, a third flow tube 8, and a fourth flow tube 9 sequentially arranged along the axis. The fourth flow tube 9 and the first branch 6-1 are reliably connected through a quick connector to ensure airtightness and maintainability. A circular first nozzle 10 and an annular second nozzle 11 are respectively provided at the ends of the second flow tube 7 and the third flow tube 8, and the first nozzle 10 and the second nozzle 11 are coaxially overlapped, that is, the second nozzle 11 is precisely sleeved outside the first nozzle 10 to form a double-stage spraying structure. The third nozzle 12 at the end of the fourth flow tube 9 is located in front of the first nozzle 10 to form a front-mounted ejector structure.

[0017] When the first nozzle 10 operates alone, the high-speed airflow is ejected through the first nozzle 10, creating a negative pressure area at the port of the third nozzle 12. External gas is entrained into the suction chamber 2 through the Venturi effect, achieving the primary entrainment effect.

[0018] When the second nozzle 11 and the first nozzle 10 operate simultaneously, a strong shearing effect is generated between the annular airflow and the central airflow in the isobaric mixing chamber 3, promoting the full mixing of the gas and improving the mixing efficiency.

[0019] As a pre-ejector, the third nozzle 12 can effectively reduce the back pressure of the first nozzle 10 with its negative pressure effect, improve the overall entrainment efficiency, and ensure the stable flow of the airflow in the constant-area mixing chamber 4.

[0020] The synergistic effect of the isobaric mixing chamber 3 and the constant-area mixing chamber 4 enables the mixed gas to achieve pressure recovery in the diffusion chamber 5, ensuring that the output airflow has a stable pressure and flow rate.

[0021] The blocking switch in the first branch 6-1 can be precisely adjusted according to the working conditions to achieve a rapid switch between different injection modes, meeting the operating requirements of the hydrogen fuel cell under different load conditions.

[0022] The inlet end of the second flow tube 7 is perpendicular to the main body 1, and its outlet end is in a tapered structure that gradually narrows along the axis of the main body 1. The inlet end of the third flow tube 8 is perpendicular to the main body 1, and its outlet end is sleeved outside the second flow tube 7 and is in a tapered structure that gradually narrows along the axis of the main body 1. The inlet end of the fourth flow tube 9 is perpendicular to the main body 1, and its outlet end is arranged outside the third flow tube 8 and is in an annular tapered structure that gradually narrows along the axis of the main body 1. The second flow tube 7 consists of an end cap 13 detachably installed on the main body 1 and a first tapered structure 14; the third flow tube 8 consists of the first tapered structure 14 and a second tapered structure 15 detachably installed on the main body 1; the fourth flow tube 9 consists of the second tapered structure 15 and a third tapered structure 16 detachably installed on the main body 1. The diameter of the first nozzle 10 is smaller than that of the second nozzle 11, and the diameter of the second nozzle 11 is smaller than that of the third nozzle 12. The second flow tube 7 and the third flow tube 8 respectively receive hydrogen after being decompressed by a pressure reducing valve; the first flow tube 6 receives hydrogen at the anode outlet of the hydrogen fuel cell stack. It should be further pointed out that the flow tube structure design of this combined nozzle ejector reflects precise gas flow control and efficient mixing effect. The linkage relationship and effect among various components are as follows: The inlet end of the second flow tube 7 is perpendicular to the main body 1 to ensure a stable direction when hydrogen enters from the pressure reducing valve; the outlet end is in a tapered structure that gradually narrows, that is, the first tapered structure 14, which accelerates the hydrogen flow through the contraction effect to form a high-speed jet. The second flow tube 7 consists of the end cap 13 and the first tapered structure 14, and the detachable design of the end cap 13 facilitates maintenance and replacement; the inlet end of the third flow tube 8 is also perpendicular to the main body 1, and the outlet end is sleeved outside the second flow tube 7 and is in a tapered structure that gradually narrows, that is, the second tapered structure 15, to form an annular air flow channel. The third flow tube 8 consists of the first tapered structure 14 and the second tapered structure 15, forming a nested structure with the second flow tube 7 to achieve the synergistic effect of the central jet and the annular air flow. The inlet end of the fourth flow tube is perpendicular to the main body 1, and the outlet end is located outside the third flow tube 8 and is in an annular tapered structure, that is, the third tapered structure 16, to further expand the air flow mixing area. The fourth flow tube 9 consists of the second tapered structure 15 and the third tapered structure 16, forming a double-layer nested structure with the third flow tube 8 to achieve multi-stage air flow mixing.

[0023] The first nozzle has the smallest diameter and is located at the outlet end of the second flow tube 7 to form a high-speed central jet, generating a negative pressure at the port of the third nozzle 12 to eject external gas. The second nozzle 11 has a larger diameter than the first nozzle 10 and is located at the outlet end of the third flow tube 8 to form an annular jet, which produces a strong shear effect with the central jet in the isobaric mixing chamber 3 to promote gas mixing. The third nozzle has the largest diameter and is located at the outlet end of the fourth flow tube 9. As a pre-ejector, its negative pressure effect further reduces the back pressure of the first nozzle 10 and improves the ejection efficiency.

[0024] The second flow tube 7 and the third flow tube 8 respectively receive hydrogen gas after pressure reduction by a pressure reducing valve to ensure stable air flow pressure; the first flow tube 6 receives hydrogen gas at the anode outlet of the hydrogen fuel cell stack to achieve recycling.

[0025] The high-speed central jet of the second flow tube 7 and the annular jet of the third flow tube 8 generate shear mixing in the isobaric mixing chamber 3 to form a uniform air flow.

[0026] The annular conical structure of the fourth flow tube 9 further expands the mixing area to ensure sufficient mixing of the air flow in the equal-area mixing chamber 4.

[0027] The high-speed jet of the first nozzle 10 forms a negative pressure at the port of the third nozzle 12, ejecting external gas into the suction chamber 2 to improve the overall ejection efficiency. The pre-ejection effect of the third nozzle 12 reduces the back pressure of the first nozzle 10 to ensure stable air flow.

[0028] The second flow tube 7, the third flow tube 8 and the fourth flow tube 9 all adopt a detachable design, which is convenient for maintenance and replacement to ensure long-term stable operation of the system. The modular design of the end cap 13, the first conical structure 14, the second conical structure 15 and the third conical structure 16 can be quickly adjusted or replaced according to the working conditions, improving the flexibility and adaptability of the system.

[0029] Through the precise cooperation of the second flow tube 7, the third flow tube 8 and the fourth flow tube 9, multi-stage air flow mixing and efficient ejection are achieved, significantly improving the gas utilization efficiency of the hydrogen fuel cell system.

[0030] The optimized design of the orifice diameters of each nozzle ensures the stability and mixing effect of the air flow and reduces energy loss.

[0031] The detachable structure design improves the maintainability and service life of the system, meeting the operating requirements of hydrogen fuel cells under different working conditions.

[0032] The usage method of this application is as follows: During the driving process of a fuel cell vehicle, according to the different output powers of the fuel cell, the ejector is set to three gears: high, medium, and low. When the fuel cell starts to operate, the first flow tube 6 is connected. When the ejector is in the low gear, the third flow tube 8 is connected to hydrogen, and the second flow tube 7 and the first branch 6-1 are blocked and closed. At this time, since the output power of the fuel cell is small, the amount of hydrogen discharged from the anode of the hydrogen fuel cell stack is also small. Therefore, the first branch 6-1 is blocked and closed. When in the medium gear, the second flow tube 7 is connected to hydrogen, and the third flow tube 8 and the first branch 6-1 are blocked and closed. Since the first nozzle 10 of the second flow tube 7 is of a circular structure, at the same flow rate, it will form a more obvious negative pressure area at the front end of the equal-area mixing chamber 4 than the circular-ring-shaped second nozzle 11 of the third flow tube 8. Therefore, when the output power of the fuel cell gradually increases and more hydrogen is generated, it is still not necessary to connect the first branch 6-1. When in the high gear, the second flow tube 7, the third flow tube 8, and the first branch 6-1 are all opened. At this time, a negative pressure is formed between the first nozzle 10 and the third nozzle 12, accelerating the mixing of the hydrogen produced by the anode of the hydrogen fuel cell stack in the first branch 6-1 with the hydrogen in the second flow tube 7 and the third flow tube 8. At the same time, a second-stage negative pressure is formed between the third nozzle 12 and the equal-area mixing chamber 4, accelerating the mixing of the hydrogen in the first flow path 6 and the injection mechanism. The hydrogen is mixed with the hydrogen discharged from the battery anode twice independently, which not only ensures the uniform mixing of the two gases but also avoids the problem of untimely hydrogen discharge from the fuel cell.

[0033] Example 2, as Figure 3 shown, a combined nozzle ejector for a hydrogen fuel cell includes a body 1. Inside the body 1, there are successively arranged an inhalation chamber 2, an isobaric mixing chamber 3, an equal-area mixing chamber 4, and a diffusion chamber 5 along the axis; the inhalation chamber 2 is connected to the first flow tube 6. A first branch 6-1 is provided on the side wall of the first flow tube 6, and a blocking switch is provided inside the first branch 6-1; a spraying structure is detachably installed on the side end of the body 1. The spraying mechanism includes a second flow tube 7, a third flow tube 8, and a fourth flow tube 9 arranged successively along the axis. The fourth flow tube 9 is connected to the first branch 6-1. Circular first nozzles 10 and circular-ring-shaped second nozzles 11 are respectively provided at the ends of the second flow tube 7 and the third flow tube 8, and the first nozzle 10 and the second nozzle 11 overlap, that is, the second nozzle 11 is sleeved outside the first nozzle 10. The third nozzle 12 at the end of the fourth flow tube 9 is located in front of the first nozzle 10, and when the first nozzle 10 or the second nozzle 11 operates, a negative pressure is formed at the port of the third nozzle 12.

[0034] The inlet end of the second flow tube 7 is perpendicular to the main body 1, and its outlet end is in a tapered structure that gradually narrows along the axis of the main body 1. The inlet end of the third flow tube 8 is perpendicular to the main body 1, and its outlet end is sleeved outside the second flow tube 7 and is in a tapered structure that gradually narrows along the axis of the main body 1. The inlet end of the fourth flow tube 9 is perpendicular to the main body 1, and its outlet end is arranged outside the third flow tube 8 and is in an annular tapered structure that gradually narrows along the axis of the main body 1.

[0035] The second flow tube 7 is composed of an end cap 13 detachably installed on the main body 1 and a first tapered structure 14; the third flow tube 8 is composed of the first tapered structure 14 and a second tapered structure 15 detachably installed on the main body 1; the fourth flow tube 9 is composed of the second tapered structure 15 and a third tapered structure 16 detachably installed on the main body 1.

[0036] The diameter of the first nozzle 10 is smaller than that of the second nozzle 11, and the diameter of the second nozzle 11 is smaller than that of the third nozzle 12.

[0037] The second flow tube 7 and the third flow tube 8 respectively receive hydrogen gas after being decompressed by a pressure reducing valve; the first flow tube 6 receives hydrogen gas at the anode outlet of the hydrogen fuel cell stack.

[0038] The first flow tube 6 includes a second branch 6-2, and the second branch 6-2 makes the first flow tube 6 be misaligned and connected to the inlet end of the suction chamber 2.

[0039] A third branch 17 is provided in the main body 1. The third branch 17 connects the third flow tube 8 and the second branch 6-2, and a fourth nozzle 18 is provided at the connection between the second branch 6-2 and the third flow tube 8. When the third flow tube 8 is connected to gas, the fourth nozzle 18 can accelerate the flow of the first flow tube 6.

[0040] Since the second flow tube 7, the third flow tube 8, and the fourth flow tube 9 are high-speed flow tubes, while the first flow tube 6 is a low-speed flow tube, when all the flow tubes are fully open, the first flow tube 6 cannot be effectively driven, resulting in poor mixing between the high-speed flow tubes and the low-speed flow tube, further leading to a reduction in the circulation volume and low combustion utilization rate. At the same time, uneven mixing may cause local concentrations to be too high or too low. Areas with too low hydrogen concentration may affect the electrochemical reaction, and areas with high concentration may pose safety hazards. In addition, uneven mixing may cause pressure pulsation, resulting in unstable operation of the ejector, generating noise or vibration, especially it can cause local accumulation of liquid water in the ejector. Especially during low-temperature startup, water vapor condenses, blocking the flow channel and affecting the hydrogen supply.

[0041] The above are only the preferred embodiments of the present application and are not used to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A combined nozzle ejector for a hydrogen fuel cell, characterized in that: The invention comprises a body (1), wherein an inhalation chamber (2), an isobaric mixing chamber (3), an isobaric mixing chamber (4) and a diffusion chamber (5) are sequentially arranged along an axis in the body (1); the inhalation chamber (2) is connected to a first flow tube (6), a first branch (6-1) is arranged on a side wall of the first flow tube (6), and a blocking switch is arranged in the first branch (6-1); a spray structure is detachably mounted on a side end of the body (1), the spray structure comprises a second flow tube (7), a third flow tube (8) and a fourth flow tube (9) sequentially arranged along the axis, the fourth flow tube (9) being connected to the first branch (6-1), a first nozzle (10) and a second nozzle (11) are respectively arranged at the end of the second flow tube (7) and the end of the third flow tube (8), and the first nozzle (10) and the second nozzle (11) are arranged to overlap, the third nozzle (12) at the end of the fourth flow tube (9) is located in front of the first nozzle (10), and when the first nozzle (10) or the second nozzle (11) is in operation, a negative pressure is formed at the port of the third nozzle (12).

2. The combined nozzle ejector for a hydrogen fuel cell according to claim 1, characterized in that: The inlet end of the second flow tube (7) is perpendicular to the body (1), and the outlet end thereof is in a tapered structure that gradually decreases along the axis of the body (1); the inlet end of the third flow tube (8) is perpendicular to the body (1), and the outlet end thereof is sleeved on the outside of the second flow tube (7) and is in a tapered structure that gradually decreases along the axis of the body (1); the inlet end of the fourth flow tube (9) is perpendicular to the body (1), and the outlet end thereof is arranged on the outside of the third flow tube (8) and is in a tapered structure that gradually decreases along the axis of the body (1).

3. The combined nozzle ejector for a hydrogen fuel cell according to claim 1, characterized in that: The second flow tube (7) is composed of an end cover (13) detachably mounted on the body (1) and a first conical structure (14); the third flow tube (8) is composed of a first conical structure (14) detachably mounted on the body (1) and a second conical structure (15); and the fourth flow tube (9) is composed of a second conical structure (15) detachably mounted on the body (1) and a third conical structure (16).

4. The combined nozzle ejector for a hydrogen fuel cell according to claim 1, characterized in that: The caliber of the first nozzle (10) is smaller than the caliber of the second nozzle (11), and the caliber of the second nozzle (11) is smaller than the caliber of the third nozzle (12).

5. The combined nozzle ejector for a hydrogen fuel cell according to claim 1, characterized in that: The second flow pipe (7) and the third flow pipe (8) respectively receive the hydrogen gas after being decompressed by the pressure reducing valve; the first flow pipe (6) receives the hydrogen gas at the anode outlet of the hydrogen fuel cell stack.

6. The combined nozzle ejector for a hydrogen fuel cell according to claim 1, characterized in that: The third nozzle (12) is a circular structure.

7. The combined nozzle ejector for a hydrogen fuel cell according to claim 1, characterized in that: The first flow tube (6) comprises a second branch (6-2), and the second branch (6-2) connects the first flow tube (6) to the inlet end of the suction chamber (2) in a staggered manner.

8. The combined nozzle ejector for a hydrogen fuel cell according to claim 7, characterized in that: A third branch (17) is provided in the body (1), the third branch (17) connecting the third flow tube (8) and the second branch (6-2), and a fourth nozzle (18) is provided at the connection between the second branch (6-2) and the third flow tube (8), and when the third flow tube (8) is connected to gas, the fourth nozzle (18) can accelerate the flow of the first flow tube (6).

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