A nozzle-extended hydrogen ejector suitable for low-power segment fuel cells

Abstract

The utility model discloses a nozzle lengthening type hydrogen ejector suitable for low power section fuel cell, including ejector main part, the ejector main part includes the high pressure fluid pipe portion and low pressure fluid pipe portion of independent each other, the high pressure fluid pipe portion includes primary fluid inlet, conical tube and primary fluid outlet, be provided with lengthening nozzle at primary fluid outlet, low pressure fluid pipe portion includes secondary fluid inlet, annular pipe, annular conical tube and secondary fluid outlet, be provided with the flow guide nozzle at secondary fluid outlet, lengthening nozzle communicates with flow guide nozzle through mixing chamber, be provided with the diffuser chamber behind mixing chamber. The utility model discloses a nozzle lengthening type hydrogen ejector suitable for low power section fuel cell can make up the defect that the ejector is poor in the low power section fuel cell injection performance, improves the hydrogen circulation capacity of low power fuel cell, thereby improves the overall performance of fuel cell system.

Description

Technical Field

[0001] This utility model relates to the field of ejector technology, and in particular to a nozzle-extended hydrogen ejector suitable for low-power fuel cells. Background Technology

[0002] Proton exchange membrane fuel cells (PEMFCs) are devices that convert chemical energy into electrical energy through electrochemical reactions. They offer advantages such as high energy density and conversion efficiency, and are clean and pollution-free, leading to their widespread application in aerospace, marine, and transportation sectors, and representing an important direction for hydrogen energy utilization. In fuel cell systems, an excess of hydrogen is required to ensure the normal operation of the PEMFC. Therefore, a hydrogen recirculation device is needed to recycle the hydrogen discharged from the outlet back to the inlet, avoiding hydrogen waste and environmental pollution. This has led to the development of hydrogen recirculation pumps and hydrogen ejectors. Compared to recirculation pumps, ejectors do not require a power source, consume no energy, have a simple structure, high reliability, and low maintenance costs, making them more suitable for application in PEMFC hydrogen recirculation systems.

[0003] Currently used ejectors are mainly designed for fixed-power fuel cells, especially for medium- and high-power fuel cells. Their applicability is limited. At low power, the ejection performance of a single ejector is poor, requiring the use of multiple ejector specifications or in conjunction with a hydrogen recirculation pump to achieve hydrogen recirculation. Furthermore, in commonly used ejectors, the high-pressure primary fluid tends to generate eddies when flowing out of the nozzle, leading to a deterioration in ejection efficiency and thus affecting the performance of the fuel cell system.

[0004] Therefore, the structure of the existing ejector needs to be redesigned or improved to overcome the above shortcomings, improve the hydrogen recirculation capability of low-power fuel cell systems, and at the same time minimize the generation of eddies, thereby improving the performance of the entire system. Summary of the Invention

[0005] The purpose of this invention is to provide a hydrogen ejector with an extended nozzle suitable for low-power fuel cells. This design can greatly improve the ejection effect of the ejector in the low-power range of fuel cells, addressing the problem of poor ejection performance at low power. At the same time, it can effectively suppress turbulence generated when high-pressure hydrogen flows out of the nozzle, thereby improving the efficiency of the hydrogen circulation system and enhancing the overall performance of the fuel cell system.

[0006] To achieve the above objectives, this utility model provides a nozzle-extended hydrogen ejector suitable for low-power fuel cells, comprising an ejector body, wherein the ejector body includes a high-pressure fluid pipe section and a low-pressure fluid pipe section that are independent of each other, the high-pressure fluid pipe section includes a primary fluid inlet, a conical pipe and a primary fluid outlet, and an extended nozzle is provided at the primary fluid outlet;

[0007] The low-pressure fluid pipe section includes a secondary fluid inlet, an annular pipe, an annular conical pipe, and a secondary fluid outlet. A guide nozzle is provided at the secondary fluid outlet. The extended nozzle is connected to the guide nozzle through a mixing chamber. A diffuser chamber is provided behind the mixing chamber.

[0008] Preferably, the primary fluid inlet is connected to the extended nozzle through the tapered tube, and a flow-rectifying grid is provided at the inlet of the extended nozzle.

[0009] Preferably, the ratio of the length of the extended nozzle to its inner diameter is 15.3.

[0010] Preferably, the secondary fluid inlet is connected to the guide nozzle in sequence through the annular pipe, the annular conical pipe, and the guide nozzle.

[0011] Preferably, an ejector outlet is provided on the other side of the diffuser chamber, and the inner diameter of the diffuser chamber gradually increases from the mixing chamber to the ejector outlet.

[0012] Preferably, the center of the extended nozzle cross-section and the center of the mixing chamber cross-section are concentric.

[0013] Preferably, the guide nozzle has a uniform radial dimension along the circumferential direction of the extended nozzle, and an annular gap is formed between the inner circumferential surface of the guide nozzle and the outer circumferential surface of the extended nozzle.

[0014] Preferably, the inner diameter of the tapered tube gradually decreases from the primary fluid inlet to the extended nozzle, and the contraction angle of the tapered tube is 15°.

[0015] Preferably, the inner diameter of the annular tapered tube gradually decreases from the annular tube to the guide nozzle.

[0016] Therefore, the present invention employs the above-mentioned extended nozzle hydrogen ejector suitable for low-power fuel cells, and the beneficial effects are as follows:

[0017] (1) This utility model effectively compensates for the low-power section ejection defect by lengthening the nozzle and designing a specific length-to-diameter ratio, combined with various guide nozzle forms and connection methods, thereby enhancing the hydrogen circulation capability and improving the overall performance of the fuel cell system.

[0018] (2) In this utility model, the extended nozzle is combined with the flow grid to convert the high-pressure hydrogen vortex into laminar flow. The guide nozzle and the annular gap design promote the uniform mixing of low-pressure hydrogen, reduce fluid resistance, and improve the efficiency of the hydrogen circulation system.

[0019] (3) This utility model requires no additional power source and consumes no energy. Through reasonable pipeline and chamber structure design, it achieves efficient mixing and pressurization of high-pressure and low-pressure hydrogen, reduces operation and maintenance costs, and is suitable for various low-power fuel cell scenarios.

[0020] The technical solution of this utility model will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0021] Figure 1 This is a cross-sectional view of an embodiment of a nozzle-extended hydrogen ejector suitable for low-power fuel cells according to this utility model;

[0022] Figure 2 This is a schematic diagram of several flow guide nozzles of an embodiment of a nozzle-extended hydrogen ejector suitable for low-power fuel cells according to this utility model;

[0023] Figure 3 This is a schematic diagram showing the connection position between the extended nozzle and the guide nozzle of an embodiment of the extended nozzle hydrogen ejector for low-power fuel cells according to this utility model;

[0024] Figure 4 This is a schematic diagram illustrating the working principle of an embodiment of a nozzle-extended hydrogen ejector suitable for low-power fuel cells according to this utility model.

[0025] Figure 5 This is a comparison diagram of the performance of a nozzle-extended hydrogen ejector and a conventional ejector, based on an embodiment of the present invention, which is suitable for low-power fuel cells.

[0026] Figure 6 This is a schematic diagram of the parameters of various parts of an embodiment of a nozzle-extended hydrogen ejector suitable for low-power fuel cells according to this utility model.

[0027] Figure Labels

[0028] 1. Primary fluid inlet; 2. Conical tube; 3. Extended nozzle; 4. Secondary fluid inlet; 5. Annular tube; 6. Annular conical tube; 7. Guide nozzle; 8. Mixing chamber; 9. Diffuser chamber; 10. Ejector outlet. Detailed Implementation

[0029] The technical solution of this utility model will be further described below with reference to the accompanying drawings and embodiments.

[0030] Unless otherwise defined, the technical or scientific terms used in this utility model shall have the ordinary meaning understood by one of ordinary skill in the art to which this utility model pertains. The terms "first," "second," and similar words used in this utility model do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0031] like Figure 1 As shown, a nozzle-extended hydrogen ejector suitable for low-power fuel cells includes an ejector body, which comprises independent high-pressure fluid pipe sections and low-pressure fluid pipe sections.

[0032] High-pressure fluid piping section:

[0033] The high-pressure fluid pipe section primarily provides a passage for high-pressure primary hydrogen flow, including a primary fluid inlet 1, a tapered pipe 2, and a primary fluid outlet. In this embodiment, the diameter D of the primary fluid inlet 1 is... p The diameter is 4 mm, serving as the initial inlet for high-pressure hydrogen; the inner diameter of the conical tube 2 gradually decreases from the primary fluid inlet 1 to the extended nozzle 3, and the contraction angle α of the conical tube 2 is... p The angle is 15° to ensure that hydrogen is accelerated inside the tube while reducing pressure loss.

[0034] An extended nozzle 3 is provided at the primary fluid outlet, and the primary fluid inlet 1 is connected to the extended nozzle 3 via a tapered pipe 2. The ratio of the length to the inner diameter of the extended nozzle 3 is 15.3. In this embodiment, the length L of the extended nozzle 3 is... p The tube is 20mm long and has an inner diameter d of 1.3mm. The extended design, combined with a specific length-to-diameter ratio, can effectively eliminate the eddies formed after high-pressure hydrogen gas is accelerated through the conical tube 2. By utilizing the laminar boundary layer theory, the turbulent eddies are transformed into stable laminar flow, reducing fluid resistance.

[0035] Meanwhile, a flow-rectifying grid is installed at the inlet of the extended nozzle 3 to further accelerate the conversion process from vortex to laminar flow through turbulence and guidance, providing a stable high-speed jet for the subsequent ejection process. In addition, the high-pressure fluid pipe can move left and right along the central axis of the extended nozzle 3 through a slide rail or guide mechanism, which facilitates dynamic optimization of the ejection effect according to different working conditions.

[0036] Low-pressure fluid piping section:

[0037] The low-pressure fluid pipe section provides a passage for low-pressure secondary hydrogen flow, including a secondary fluid inlet 4, an annular pipe 5, an annular conical pipe 6, and a secondary fluid outlet. A guide nozzle 7 is installed at the secondary fluid outlet. The secondary fluid inlet 4 is connected to the guide nozzle 7 sequentially through the annular pipe 5 and the annular conical pipe 6. In this embodiment, the diameter D of the secondary fluid inlet 4 is... s The diameter d of the annular tube 5 is 5mm. s The diameter is 8 mm, forming a buffer zone to stabilize the inflow of low-pressure hydrogen.

[0038] The inner diameter of the annular tapered tube 6 gradually decreases from the annular tube 5 to the guide nozzle 7. The contraction angle of the annular tapered tube 6, i.e., the inlet angle β of the guide nozzle 7, is 30°. The outlet angle α of the guide nozzle 7 is 60°, and the inlet inner angle α... s The parameters, including a 160° angle, an outlet wall thickness h of 0.4 mm, and an outlet size L of 0.8 mm for the guide nozzle 7, ensure that low-pressure hydrogen gas is properly accelerated and guided within the pipe.

[0039] The guide nozzle 7 serves to guide the flow of low-pressure hydrogen. The guide nozzle 7 has a uniform radial dimension along the circumference of the extended nozzle 3. An annular gap is formed between the inner circumferential surface of the guide nozzle 7 and the outer circumferential surface of the extended nozzle 3. This structure enables the low-pressure hydrogen to enter the mixing region uniformly under the entrainment effect of the high-pressure jet.

[0040] In addition, the low-pressure fluid pipe section can use a guide nozzle 7 at any angle, such as... Figure 2 As shown in Figure 2, (a), (b), (c), (d), and (e) are five different types of jet nozzles 7. Each jet nozzle 7 can be adapted to different jetting requirements by changing the outlet shape, such as enhancing the mixing effect or adjusting the jet diffusion angle.

[0041] Mixing chamber 8 and diffuser chamber 9:

[0042] The extended nozzle 3 is connected to the guide nozzle 7 via a mixing chamber 8. The mixing chamber 8 is used to mix high-pressure hydrogen gas and low-pressure hydrogen gas ejected by the high-pressure hydrogen gas. The ratio of the length to the inner diameter of the mixing chamber 8 is approximately 0.12. In this embodiment, the length L of the mixing chamber 8 is... m It is 30mm, with an inner diameter D. m The diameter is 3.7 mm, and it is necessary to ensure that the center of the cross-section of the extended nozzle 3 and the center of the cross-section of the mixing chamber 8 are concentric to ensure that the two fluids are fully mixed in a symmetrical environment. The length and inner diameter parameters of the mixing chamber 8 are optimized according to the mixing efficiency formula, which can achieve rapid mixing of hydrogen in a limited space.

[0043] A diffuser chamber 9 is disposed behind the mixing chamber 8. The inner diameter of the diffuser chamber 9 gradually increases from the mixing chamber 8 to the ejector outlet 10. In this embodiment, the opening angle θ of the diffuser chamber 9 is set.s With a pressure of 18°, this structural design can decelerate and pressurize the high-speed flowing hydrogen after mixing, effectively converting kinetic energy into static pressure energy.

[0044] An ejector outlet 10 is provided on the other side of the diffuser chamber 9. The inner diameter D0 of the ejector outlet 10 is 7 mm. The mixing chamber 8 and the ejector outlet 10 are connected through the diffuser chamber 9. The hydrogen gas, after being pressurized by the diffuser chamber 9, flows out from the ejector outlet 10 to meet the hydrogen pressure and flow requirements of the fuel cell, thus completing the entire hydrogen cycle process.

[0045] like Figure 3 As shown, in this embodiment, the extended nozzle 3 and the guide nozzle 7 have three communication methods:

[0046] 1. The extended nozzle 3 and the guide nozzle 7 are connected at the annular cone tube 6, such as... Figure 3 As shown in (a), this method can guide low-pressure hydrogen to contact the high-pressure jet in advance, thereby enhancing the entrainment effect.

[0047] 2. The extended nozzle 3 and the guide nozzle 7 are connected at the inlet of the mixing chamber 8, such as... Figure 3 As shown in (b), this method facilitates control of the initial mixing state of the fluid.

[0048] 3. The extended nozzle 3 and the guide nozzle 7 are connected within the mixing chamber 8, such as... Figure 3 As shown in (c), this connectivity method can utilize a larger space to achieve more thorough mixing.

[0049] The above three methods can be flexibly selected according to the actual working conditions, further improving the adaptability and efficiency of the ejector in the low-power range.

[0050] The specific working principle of this utility model device is as follows:

[0051] like Figure 4 As shown, high-pressure primary hydrogen gas (shaded area in the figure) is accelerated through primary fluid inlet 1 and conical tube 2, then enters elongated nozzle 3 with a length-to-diameter ratio of 15.3. Under the action of the flow straightening grid, the turbulent eddies are transformed into stable laminar flow, which is then ejected at a uniform and high speed. When the high-pressure primary hydrogen gas reaches region L2 through the elongated nozzle, the boundary layer gradually thickens and eventually separates due to the difference between the fluid velocity and the wall velocity. After the boundary layer separation point, the fluid no longer flows tightly against the wall, but forms a flow region detached from the wall. In this region, the flow direction and velocity distribution of the fluid change drastically, causing fluid particles to collide and rotate, thus generating eddies.

[0052] These vortices have a strong entrainment effect, creating a localized low-pressure region within the ejector. Simultaneously, low-pressure secondary hydrogen gas flows in from the secondary fluid inlet 4, passing through the annular pipe 5 and the annular cone pipe 6 for buffering and acceleration, and is positioned in the annular gap under the guidance of the guide nozzle 7. Due to the pressure difference between the low pressure generated by the vortex in region L2 and the region containing the low-pressure secondary hydrogen gas, the low-pressure secondary hydrogen gas is entrained by the vortex and drawn out of the guide nozzle under pressure, rapidly entering the mixing region. Within the mixing region, the low-pressure secondary hydrogen gas comes into full contact with the high-speed, high-pressure primary hydrogen gas. The two fluids interact, exchanging momentum and energy, thus achieving uniform mixing.

[0053] The length-to-inner-diameter ratio of the mixing chamber 8 is approximately 0.12, and the design of the extended nozzle 3's cross-section center being concentric with the cross-section center of the mixing chamber 8 provides excellent spatial conditions for the thorough mixing of the two fluids. The mixed hydrogen gas enters the diffuser chamber 9. As the inner diameter of the diffuser chamber 9 gradually increases, the flow velocity decreases, kinetic energy is converted into static pressure energy, and the pressure increases. Finally, it flows out from the ejector outlet 10 to meet the fuel cell's requirements for hydrogen pressure and flow rate, completing the entire hydrogen ejection cycle.

[0054] like Figure 5 As shown in the figure, comparing the performance of the traditional ejector and the extended nozzle ejector of this utility model, it can be seen from the figure that the extended nozzle ejector in this embodiment has improved the key performance indicators of primary fluid flow rate, secondary fluid flow rate and ejection ratio compared with the traditional ejector, which reflects the advantages of the extended nozzle ejector in hydrogen ejection and is suitable for improving the hydrogen circulation capacity of low-power fuel cells.

[0055] Therefore, this utility model adopts the above-mentioned nozzle-extended hydrogen ejector suitable for low-power fuel cells. Through structural design such as extended nozzle, rectifier grid, and annular gap, the flow path of high and low pressure hydrogen is optimized to achieve efficient mixing and pressurization, significantly improve the ejection performance in the low-power range, reduce fluid resistance, and improve the hydrogen circulation efficiency and overall system performance of the fuel cell.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and not to limit it. Although the utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solution of this utility model, and these modifications or equivalent substitutions cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of this utility model.

Claims

1. A nozzle-extended hydrogen ejector suitable for use in low power range fuel cells, characterized by: The ejector body comprises a high-pressure fluid pipe part and a low-pressure fluid pipe part, the high-pressure fluid pipe part comprises a primary fluid inlet, a conical pipe and a primary fluid outlet, and an elongated nozzle is arranged at the primary fluid outlet; The primary fluid inlet is communicated with the elongated nozzle through the conical pipe, and a flow regulation grid is arranged at the inlet of the elongated nozzle; the length-diameter ratio of the elongated nozzle is 15.3; The low-pressure fluid pipe part comprises a secondary fluid inlet, an annular pipe, an annular conical pipe and a secondary fluid outlet, a flow guide nozzle is arranged at the secondary fluid outlet, the elongated nozzle is communicated with the flow guide nozzle through a mixing chamber, and a diffuser chamber is arranged behind the mixing chamber; The secondary fluid inlet is communicated with the flow guide nozzle through the annular pipe and the annular conical pipe in sequence; the inner diameter of the conical pipe gradually decreases from the primary fluid inlet to the elongated nozzle, and the contraction angle of the conical pipe is 15°.

2. A nozzle-extended hydrogen ejector suitable for use with low-power range fuel cells according to claim 1, characterized in that: The diffuser chamber is arranged with an ejector outlet on the other side, and the inner diameter of the diffuser chamber gradually increases from the mixing chamber to the ejector outlet.

3. A nozzle-extended hydrogen ejector suitable for use with low power range fuel cells according to claim 1, wherein: The center of the cross section of the elongated nozzle and the center of the cross section of the mixing chamber are concentric.

4. A nozzle-extended hydrogen ejector suitable for use with low power range fuel cells according to claim 1, wherein: The flow guide nozzle has a uniform radial dimension along the circumferential direction of the elongated nozzle, and an annular gap is formed between the inner circumferential surface of the flow guide nozzle and the outer circumferential surface of the elongated nozzle.

5. A nozzle-extended hydrogen ejector suitable for use with low power range fuel cells according to claim 1, wherein: The inner diameter of the annular conical pipe gradually decreases from the annular pipe to the flow guide nozzle.

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