Composite ejector, use method thereof and fuel cell system

Abstract

The invention discloses a composite ejector, a use method thereof and a fuel cell system, and belongs to the technical field of fuel cells. The ejector comprises a first ejection section and a second ejection section; a spray pipe is mounted at one end of the first injection section, and a nozzle section is arranged at the other end of the first injection section; an injection cavity is defined by the nozzle section and the second injection section; a hole channel is formed in the nozzle section and comprises a first flow stabilizing chamber and a first diffusion section. An inlet of the second injection section is connected with the first injection section, an outlet channel is arranged at an outlet of the second injection section, and the outlet channel comprises a second flow stabilizing chamber and a second diffusion section; a nozzle mechanism is arranged at the end, close to the second flow stabilizing chamber, of the nozzle section and provided with a nozzle, and the injection cavity communicates with the second flow stabilizing chamber through the nozzle. According to the invention, the main injection port and the bypass injection port are integrated, the acceleration effect after one-time injection is realized in a composite injection mode, the utilization rate of fuel gas is improved, and the injection time and the starting time are shortened.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and more specifically, to a composite ejector, a method for using the same, and a fuel cell system. Background Art

[0002] In a traditional fuel cell system, the injection of fuel is a key step, which directly affects the performance and efficiency of the fuel cell. The injection of fuel is achieved by an injector, which is responsible for introducing fuel into the fuel cell stack or combustion chamber in an appropriate manner for further reactions and energy conversion.

[0003] The working principle of the traditional single-hole injection scheme is as follows: The injector includes a feed channel and a nozzle. After the high-pressure gas passes through the nozzle, due to adiabatic expansion, the pressure energy in the high-pressure moving fluid is converted into kinetic energy, resulting in an increase in flow velocity but a decrease in pressure. At this time, due to the pressure drop of the moving fluid, a low-pressure area will be formed in the mixing chamber. Due to the existence of the low-pressure area, the mixing chamber will mix the inhaled fluid with the moving fluid in the mixing chamber. The mixed fluid then enters a diffuser in the shape of a Venturi tube, where they are fully mixed and the kinetic energy is reconverted into pressure energy. Finally, a mixed fluid with a pressure higher than the low-pressure inhaled fluid but lower than the high-pressure moving fluid will be produced.

[0004] However, the traditional single-hole injection scheme uses a single nozzle to introduce high-pressure moving fluid into the mixing chamber. Although this scheme is simple, it has the following problems: Single injection has problems such as a single injection method, low fuel utilization efficiency, and long injection time, which are mainly related to the following factors: 1. Single injection method: Single injection usually can only inject fuel through a single hole or channel, which limits the flow range of fuel and the diversity of injection methods, and cannot meet the full-power injection requirements from large flow to small flow; 2. Low fuel utilization efficiency: Since the injection ratio of the single-hole injector is limited by the aperture, it is impossible to efficiently utilize the driving fluid, and the utilization efficiency is relatively low. The driving fluid cannot fully drive the injected fluid forward, wasting fuel resources; 3. Long injection time and startup time: Since single injection cannot quickly adjust the fuel flow rate, it often cannot meet the requirements of large-range load changes or rapid startup. The long injection time and startup time will affect the dynamic response and working efficiency of the fuel cell system.

[0005] For example, Chinese Utility Model Patent with application number CN201621090937.3 discloses an ejector for ejecting cryogenic boil-off gas of liquefied natural gas by ambient temperature natural gas. It includes a nozzle tube. One end of the nozzle tube is the inlet end, and the other end is the outlet end. The nozzle tube is sequentially provided with a suction chamber, a mixing chamber, and a diffuser chamber from the inlet end to the outlet end. The mixing chamber is a straight pipe section, the diffuser chamber is a diverging pipe, and the connection between the suction chamber and the mixing chamber is a converging pipe section; a nozzle extending towards the suction chamber is arranged at the inlet end of the nozzle tube. The nozzle is sequentially provided with a converging section and a diverging section from the nozzle inlet to the nozzle outlet; an injection tube is arranged on one side of the suction chamber. For this single-hole injection scheme, it cannot cover the full-power injection requirements from large flow rate to small flow rate, and the single-hole ejector can only introduce fuel through one hole, resulting in uneven pressure distribution of the fuel, which affects the performance and efficiency of the fuel cell. In addition, the single-hole ejector cannot flexibly adjust the fuel flow rate, and the inability to adjust in a timely manner under different load conditions will affect the performance and stability of the system.

[0006] In summary, the traditional single-hole injection scheme has problems such as single injection method, low fuel utilization efficiency, and long injection and start-up times, which limit the performance and efficiency of the fuel cell system. Summary of the Invention

[0007] The present invention provides a compound ejector, its usage method, and a fuel cell system to solve the problems of single injection method, low fuel utilization efficiency, and long injection and start-up times existing in the traditional single-hole injection scheme.

[0008] To solve the above technical problems, the technical solution of the present invention is as follows: According to the first aspect of the present invention, the present invention provides a compound ejector, which includes a first ejecting section and a second ejecting section connected to each other. The second ejecting section is sleeved outside one end of the first ejecting section and encloses an installation cavity with the first ejecting section; The first ejecting section is a first cavity with openings at both axial ends. A nozzle tube is installed at the end of the first ejecting section away from the second ejecting section. A nozzle section is provided at the end of the first ejecting section extending into the second ejecting section; an ejecting cavity is enclosed by the outer wall of the nozzle section and the inner wall of the second ejecting section; an ejecting port communicating with the first ejecting section is provided on the side wall of the first ejecting section; a channel is opened inside the nozzle section, and the channel includes a first steady flow chamber communicating the nozzle section with the first ejecting section and a first diffusing section communicating with the first steady flow chamber; The second ejector section is a second cavity with openings at both axial ends. The entrance of the second ejector section is connected to the first ejector section. An exit channel is provided at the exit of the second ejector section. The exit channel includes a second flow stabilization chamber and a second diffuser section communicating with the outside. The second flow stabilization chamber communicates with the first diffuser section. A second jet orifice communicating with the second ejector section is provided on the side wall of the second ejector section. A nozzle mechanism is provided at one end of the nozzle section close to the second flow stabilization chamber. The nozzle mechanism is provided with a nozzle. The ejector cavity communicates with the second flow stabilization chamber through the nozzle.

[0009] Furthermore, a first nozzle is provided at one end of the nozzle tube extending into the interior of the first ejector section, and a first jet orifice is provided at one end of the nozzle tube located outside the installation cavity.

[0010] Furthermore, the nozzle mechanism is a cylindrical structure provided at one end of the nozzle section. A fluid channel is formed inside the cylindrical structure, and the fluid channel communicates with the second flow stabilization chamber. A second nozzle is obliquely provided on the side wall of the cylindrical structure. The entrance end of the second nozzle is located in the ejector cavity, and the exit end of the second nozzle is located in the second flow stabilization chamber.

[0011] Furthermore, at least one second nozzle is provided, and a plurality of the second nozzles are annularly distributed on the side wall of the cylindrical structure.

[0012] Furthermore, the number of the second nozzles is 2 - 16, and the incident angle of the second nozzles is 2 - 40°.

[0013] Furthermore, the nozzle mechanism is formed by a gap between the outer side wall of the nozzle section and the inner side wall of the second ejector section, and the gap is a third nozzle.

[0014] Furthermore, the third nozzle is an annular nozzle, and the ejector cavity communicates with the second flow stabilization chamber through the third nozzle.

[0015] Furthermore, one end of the first diffuser section close to the first flow stabilization chamber is a first entrance end, and one end of the first diffuser section close to the second flow stabilization chamber is a first exit end. The inner diameter of the first diffuser section gradually increases from the first entrance end to the first exit end. One end of the second diffuser section close to the second flow stabilization chamber is a second entrance end, and one end of the second diffuser section close to the outside is a second exit end. The inner diameter of the second diffuser section gradually increases from the second entrance end to the second exit end.

[0016] According to the second aspect of the present invention, the present invention provides a method for using a compound ejector. Based on the foregoing compound ejector, the method for using includes the following steps: A first fluid is introduced through a first jet orifice. After being accelerated by a first nozzle, the first fluid mixes with a second fluid sucked in through an ejector orifice in a first flow stabilization chamber. The mixed fluid is a first mixed fluid. The first mixed fluid reaches a first diffuser section through the first flow stabilization chamber. A third fluid sucked in through a second jet orifice is accelerated by a nozzle mechanism provided at one end of a nozzle section. The accelerated third fluid mixes with the first mixed fluid from the first diffuser section to form a second mixed fluid. The second mixed fluid enters a second diffuser section through a second flow stabilization chamber and is output to the outside from a second outlet end of the second diffuser section.

[0017] According to a third aspect of the present invention, there is provided a fuel cell system in which the aforementioned compound ejector is installed.

[0018] Compared with the prior art, the beneficial effects of the technical solution of the present invention are as follows: The present invention provides a compound ejector, its usage method, and a fuel cell system, which can solve the problems existing in the single ejector currently on the market. Compared with the traditional ejector method that has a single ejector mode, low fuel utilization efficiency, and long ejector time and startup time, the present invention integrates a main ejector and a bypass ejector orifice, and realizes an acceleration effect after a single ejection through a compound ejection method, improving the utilization rate of fuel gas and shortening the ejector time and startup time.

[0019] Specifically, the present invention can improve the working performance. By changing the number and aperture of the second group of nozzles, the exhaust gas and drainage during the ejection process are utilized. The compound ejection structure meets the working conditions at the idle point and the working conditions under large flow rates. Compared with the single ejector structure, the compound ejection has higher efficiency and better ejection effect. Usually, the single ejector structure needs to add a hydrogen pump at the idle point working condition or use two single - structure ejectors to meet the usage requirements of the equipment. By using the compound ejection method to eject the fluid through secondary ejection, while reducing the volume, it avoids the maintenance cost brought by using a hydrogen pump and the usage cost brought by using a double ejector. In addition, due to the compound ejection method, the fluid is accelerated by the second ejection section immediately after passing through the first ejection area, greatly reducing the energy loss, meeting the full - working - condition use and increasing the stability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0021] Figure 1 Schematic structural diagram of the composite ejector of the present invention; Figure 2 Schematic structural diagram of the composite ejector of the present invention when a second nozzle is adopted at the nozzle mechanism; Figure 3 Partial enlarged schematic diagram of the second nozzle of the composite ejector of the present invention; Figure 4 Axial schematic structural diagram of the second nozzle of the composite ejector of the present invention; Figure 5 Schematic structural diagram of the composite ejector of the present invention when a third nozzle is adopted at the nozzle mechanism; Figure 6 Partial enlarged schematic diagram of the third nozzle of the composite ejector of the present invention; Figure 7 Schematic structural diagram of the experimental test bench; Figure 8 Schematic diagram of the performance comparison curve between the composite ejector of the present invention and the existing single ejector; Among them, a1 is the entrainment ratio of the single ejector under a pressure difference of 4 kPa, and b1 is the entrainment ratio of the single ejector under a pressure difference of 14 kPa; a2 is the entrainment ratio of the composite ejector under a pressure difference of 4 kPa, and b2 is the entrainment ratio of the composite ejector under a pressure difference of 14 kPa; A is the pressure at the working fluid inlet under a pressure difference of 4 kPa, and B is the pressure at the working fluid inlet under a pressure difference of 14 kPa; Description of the marks in the figure: 1. Entrainment port; 2. First jet port; 3. First nozzle; 4. Second jet port; 5. First steady flow chamber; 6. First diffuser section; 7. Nozzle section; 8. Second steady flow chamber; 9. Second diffuser section; 10. Entrainment cavity; 11. Second nozzle; 12. Third nozzle. Detailed implementation manners

[0022] In order to better understand the purpose, structure and function of the present invention, the technical solutions of the present invention will be further described in detail below with reference to the drawings and specific preferred embodiments.

[0023] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by terms such as "left side", "right side", "upper part", "lower part", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. "First", "second", etc. do not represent the importance of components, so it cannot be understood as a limitation to the present invention. The specific dimensions adopted in the embodiments are only for illustrating the technical solutions by way of example and do not limit the protection scope of the present invention. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0024] Unless otherwise clearly specified and defined, terms such as "installation", "setting", "connection", "fixation", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances. Embodiment 1:

[0025] As Figure 1 shown, the present invention provides a technical solution: a composite ejector, including a first ejecting section and a second ejecting section connected to each other. The second ejecting section is sleeved outside one end of the first ejecting section and encloses an installation cavity with the first ejecting section, for ejecting the medium to the target area by means of composite ejection. Specifically, the connection mode between the first ejecting section and the second ejecting section is a threaded connection; an internal thread is provided on the side wall of the second ejecting section close to one end of the first ejecting section, and a corresponding external thread is provided on the first ejecting section. The first ejecting section is a first cavity with openings at both axial ends. A nozzle is installed at one end of the first ejecting section far from the second ejecting section, and a nozzle section 7 is provided at the end of the first ejecting section extending into the second ejecting section; an ejecting cavity 10 is enclosed by the outer wall of the nozzle section 7 and the inner wall of the second ejecting section; an ejecting port 1 communicating with the first ejecting section is provided on the side wall of the first ejecting section; a hole is opened inside the nozzle section 7, and the hole includes a first steady flow chamber 5 communicating the nozzle section 7 with the first ejecting section and a first diffuser section 6 communicating with the first steady flow chamber 5. The second ejector section is a second cavity with openings at both axial ends. The inlet of the second ejector section is connected to the first ejector section, and an outlet channel is provided at the outlet of the second ejector section. The outlet channel includes a second steady flow chamber 8 and a second diffuser section 9 communicating with the outside. The second steady flow chamber 8 communicates with the first diffuser section 6. A second jet orifice 4 communicating with the second ejector section is provided on the side wall of the second ejector section. A nozzle mechanism is provided at one end of the nozzle section 7 close to the second steady flow chamber 8. The nozzle mechanism is provided with a nozzle, and the ejector cavity 10 communicates with the second steady flow chamber 8 through the nozzle. Among them, the composite section, that is, the nozzle mechanism of the second ejector section, can be designed with an annular slit, annular porous, or multi-groove. The advantage of such a design is that it can perform secondary acceleration on the fluid, improve the utilization efficiency of the fuel, and enable the ejector to complete more ejection tasks in a shorter time.

[0026] Furthermore, a first nozzle 3 is provided at one end of the nozzle tube extending into the first ejector section, and a first jet orifice 2 is provided at one end of the nozzle tube located outside the installation cavity.

[0027] Furthermore, one end of the first diffuser section 6 close to the first steady flow chamber 5 is the first inlet end, and one end of the first diffuser section 6 close to the second steady flow chamber 8 is the first outlet end. The inner diameter of the first diffuser section 6 gradually increases from the first inlet end to the first outlet end. One end of the second diffuser section 9 close to the second steady flow chamber 8 is the second inlet end, and one end of the second diffuser section 9 close to the outside is the second outlet end. The inner diameter of the second diffuser section 9 gradually increases from the second inlet end to the second outlet end.

[0028] This embodiment provides a composite ejection solution, aiming to solve the problems existing in the single ejection on the current market. Due to the single ejection method in the traditional solution, the utilization efficiency of the fuel is relatively low, and at the same time, the ejection time and start-up time are relatively long. In order to improve the utilization rate of the fuel gas and shorten the ejection time and start-up time, the present invention integrates the main ejection and the bypass ejection orifice, and realizes the acceleration effect after the first ejection through the composite ejection method; by optimizing the structure of the composite ejection nozzle and the design of the mixing chamber, the fluid can obtain kinetic energy again to achieve secondary acceleration, thereby improving the efficiency and mixing effect of the ejector.

[0029] The design of the composite ejection solution has been verified by fluid mechanics and experiments. The internal channel at the end of the nozzle body of the nozzle head includes a locally tapered channel that is connected and smoothly transitions and has been verified by fluid mechanics and an ejection hole channel with a uniform inner diameter that has been verified by fluid mechanics.

[0030] In addition, the design of the quick-change nozzle verified by fluid mechanics makes nozzle replacement simple and fast, improving the convenience of maintenance and repair. The compound ejector scheme has good versatility and maintainability, and can provide effectively verified support by fluid mechanics for the stable operation of the fuel cell system.

[0031] Therefore, the compound ejector scheme of the present invention has the advantages of improving the utilization rate of fuel gas, shortening the ejector time and start-up time, and provides a solution verified by fluid mechanics for improving the performance and efficiency of the fuel cell system. Embodiment 2:

[0032] On the basis of Embodiment 1, referring to Figures 2 - 4 , the nozzle mechanism is a cylindrical structure arranged at one end of the nozzle section 7, a fluid passage is opened inside the cylindrical structure, and the fluid passage communicates with the second steady flow chamber 8; A second nozzle 11 is obliquely opened on the side wall of the cylindrical structure, the inlet end of the second nozzle 11 is located in the ejector chamber 10, and the outlet end of the second nozzle 11 is located in the second steady flow chamber 8.

[0033] Furthermore, at least one second nozzle 11 is provided, and a plurality of the second nozzles 11 are annularly distributed on the side wall of the cylindrical structure.

[0034] Furthermore, the number of the second nozzles 11 is 2-16, and the incident angle of the second nozzles 11 is 2-40°. Embodiment 3:

[0035] On the basis of Embodiment 1, referring to Figures 5 - 6 , the nozzle mechanism is formed by the gap between the outer side wall of the nozzle section 7 and the inner side wall of the second ejector section, and the gap is a third nozzle 12, and this scheme is mainly used for the ejector scheme under large flow rates.

[0036] Furthermore, the third nozzle 12 is an annular nozzle, and the ejector chamber 10 communicates with the second steady flow chamber 8 through the third nozzle 12. Embodiment 4:

[0037] The present invention provides a technical solution: a method for using a compound ejector. Based on the foregoing compound ejector, the method for using includes the following steps: Inject high-pressure first fluid from the first jet port 2, and the first fluid becomes a high-speed and low-pressure fluid after being accelerated by the first nozzle 3. After becoming a high-speed and low-pressure fluid, the first fluid mixes with the second fluid inhaled through the ejector port 1 through the first steady flow chamber 5, and the mixed fluid is the first mixed fluid; the first mixed fluid comes to the first diffuser section 6 through the first steady flow chamber 5; The second jet port 4 sucks in the supplementary third fluid, which is accelerated by a nozzle mechanism provided at one end of the nozzle section 7 to become a high-speed and low-pressure fluid; the third fluid after becoming a high-speed and low-pressure fluid is mixed with the first mixed fluid from the first diffuser section 6 to form a second mixed fluid; the first mixed fluid from the first diffuser section 6 passes through the nozzle section 7 to generate a third high-speed and low-pressure fluid for further acceleration, so that the ejector port 1 sucks in more fluid; the second mixed fluid enters the second diffuser section 9 through the second steady flow chamber 8 and is output to the outside from the second outlet end of the second diffuser section 9. Embodiment 5:

[0038] The present invention provides a technical solution: a fuel cell system, characterized in that the aforementioned compound ejector is installed in the fuel cell system.

[0039] Working principle: After the gas passes through the first nozzle 3, the flow rate increases but the pressure drops. At this time, due to the pressure drop of the moving fluid, a low-pressure area is formed in the first steady flow chamber 5 of the first ejector section. Due to the existence of the low-pressure area, the first mixing chamber of the first ejector section will mix the sucked fluid with the front-end moving fluid in the first steady flow chamber 5. The mixed fluid then enters the first diffuser section 6 of the venturi tube, and then the first diffuser section 6 mixes it. Since single-hole ejection is difficult to cover all operating conditions, for this reason, the compound bypass ejector section, that is, the second ejector section, is opened when the first ejector section cannot meet the operating conditions. The gas flow rate increases rapidly through the second group of nozzles, but the pressure drop trend is not obvious. Since the mixed fluid formed in the first diffuser section 6 keeps moving forward, after further acceleration by the second group of nozzles, a secondary high-speed area is formed. The fluid ejected from the first inlet port will further increase to meet the operating conditions that cannot be met in the first ejector section. In addition, according to different ejection ratio requirements, by changing the number and shape of the nozzle groups in the second ejector section, the flow rate can be increased or decreased to achieve the target ejection requirements. At present, according to the operating conditions, the number of nozzles in the second ejector section is adjusted to 2 - 16, which are annularly distributed at specific positions of the first diffuser section 6, and the nozzle aperture can be changed according to the ejection requirements. After being accelerated by the second nozzle, the fluid is accelerated to the second diffuser section 9 and is discharged through the outlet section after diffusion stabilization.

[0040] The present invention can utilize the exhaust gas and drainage during the ejection process by changing the number and aperture of the second group of nozzles, and meet the operating conditions at the idle point and the operating conditions under large flow rates through the compound ejection structure. Compared with the single ejection structure, the compound ejection has higher efficiency and better ejection effect. Usually, the single ejection structure needs to add a hydrogen pump at the idle point or use two single-structure ejectors to meet the usage requirements of the equipment. By using the compound ejection method to eject the fluid through secondary ejection, while reducing the volume, it avoids the maintenance cost brought by using a hydrogen pump and the usage cost brought by using a double ejector.

[0041] In addition, due to the adoption of the compound ejector method, the fluid is accelerated by the second ejector section immediately after passing through the first ejector section, greatly reducing the energy loss, increasing the stability of the system while meeting the full working conditions.

[0042] Beneficial effects are proved as follows: The working fluid inlet, the first ejector fluid inlet (the first jet port 2), the second ejector fluid inlet (the second jet port 4), and the mixed fluid outlet of the ejector are the test connection points and are connected to the test bench. The pipe diameter of the connection between the bench and the ejector is equal to the pipe diameters of the inlet and outlet of the ejector itself.

[0043] For the static pressure measurement at the inlet and outlet of the ejector, a circular-section measurement pipe with a straight and smooth inner wall is used. The pipe area is larger than the area of the connected inlet and outlet. According to the pressure measurement regulations in 4.3 of GB / T 23341.2-2018, the pipe length is not less than 5 times the pipe diameter, and the straight section length (in the direction of the air flow) before the static pressure measurement point is not less than 2 times the pipe diameter. The accuracy of the pressure sensor meets the regulations in Table 1, and the arrangement position is as Figure 7 shown.

[0044] Test environment: The test temperature is 30 °C, the test high-pressure gas is compressed air; the test is carried out under the environment of normal atmospheric pressure, ensuring natural ventilation and no air pollution.

[0045] Table 1. Main measuring devices and accuracies:

[0046] Test steps: Select the corresponding pressure difference value within the working pressure difference range of the ejector according to the technical requirements of the ejector. The first ejector fluid inlet (the first jet port 2) and the second ejector fluid inlet (the second jet port 4) respectively make the values of the second pressure sensor and the third pressure sensor at a reference value through the third pressure regulating valve. Adjust the outlet pressure of the ejector and the working fluid flow rate of the ejector for testing. Wait until the displayed values of pressure, flow rate, etc. in the test data are stable, and record the relevant data of flow rate and pressure. Calculate according to the ejector ratio formula, conduct a series of measurements under different pressure differences and flow rates, calculate the ejector ratio, and obtain the MAP diagram of the ejector pressure difference, flow rate, ejector ratio, and working fluid inlet pressure.

[0047] Ejector ratio: The ratio of the mass flow rate me of the low-pressure ejector fluid to the mass flow rate mw of the high-pressure working fluid, dimensionless, represented by the symbol ω.

[0048] ω = me / mw The specific test method of the compound ejector is as follows: 1. Connect the ejector to be tested when the pipeline gas source is confirmed to be closed and there is no pressure inside the pipeline; 2. Open the high-pressure gas source and observe the first pressure sensor, and adjust the first pressure regulating valve to control the pressure at the specified value; 3. Start testing the composite ejector. Test according to different pressure differentials and working pressures. Adjust the third pressure regulating valve at the ejector outlet and make the back pressure reach the target pressure value and target pressure differential of the second pressure sensor and the third pressure sensor. After the pressure and flow are stable, record the measured flow values ​​of the first flow sensor and the second flow sensor and the pressure values ​​of the fourth pressure sensor and the third pressure sensor; 4. Repeat step 3 until all pressure differentials to be tested under the set working fluid inlet flow rate are tested and recorded; 5. During the test, the value of each test point should be measured after the control parameters are adjusted to the specified value and stabilized for 3 minutes. Each point is measured 5 times and the average value is taken during calculation; 6. After the test is completed, turn off the gas source first, and set the back pressure valve controller and flow controller to full open to relieve the pipeline pressure.

[0049] Test Results: Comparison curve of performance between composite ejector and single ejector as shown in Figure 8 As shown, Δp represents the pressure difference of the injection, which is the difference between the outlet pressure of the injection fluid and the inlet pressure of the injection fluid, and the unit is kPa.

[0050] It can be seen that under a pressure difference of 4kPa, the ejection ratio of the composite ejector first increases and then decreases with the increase of flow rate, with the maximum ejection ratio reaching 1.84 and the minimum ejection ratio being 1.69. As the pressure difference continues to increase, the ejection ratio gradually decreases. Under a pressure difference of 14kPa, the maximum ejection ratio is 1.52 and the minimum ejection ratio is 1.38.

[0051] In addition, the comparison between the composite ejector and the original single-hole ejection scheme shows that under a pressure difference of 4kPa, at low flow rates, the ejection ratio of the composite ejector is smaller than that of the single-hole ejector, and the maximum difference between the two is 0.2. As the flow rate increases, the ejection ratio of the composite ejector gradually becomes higher than that of the single-hole ejector. At 700slpm, the ejection ratio of the composite ejector is 0.27 higher than that of the single-hole ejector. In addition, as the pressure difference increases, at high flow rates, the ejection ratio of the composite ejector scheme is also significantly better than that of the single-hole ejector. It can be seen that the composite ejector can solve the problems of low fuel injection efficiency and insufficient energy utilization caused by the use of single-hole ejectors in traditional hydrogen supply systems.

[0052] ​Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation manners here. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention.

Claims

1. A composite ejector, characterized in that: It comprises a first ejection section and a second ejection section connected to each other, wherein the second ejection section is sleeved on the outside of one end of the first ejection section to enclose an installation cavity with the first ejection section; The first ejection section is a first cavity with two axial ends open, a nozzle is installed at one end of the first ejection section away from the second ejection section, and a nozzle section (7) is provided at one end of the first ejection section extending into the second ejection section; the outer wall of the nozzle section (7) and the inner wall of the second ejection section enclose an ejection cavity (10); an ejection port (1) connected to the first ejection section is provided on the side wall of the first ejection section; a channel is opened inside the nozzle section (7), and the channel includes a first stabilizing chamber (5) connecting the nozzle section (7) and the first ejection section, and a first diffuser section (6) connected to the first stabilizing chamber (5); The second ejection section is a second cavity with openings at both axial ends. The inlet of the second ejection section is connected to the first ejection section. An outlet channel is provided at the outlet of the second ejection section. The outlet channel comprises a second stabilizing chamber (8) and a second diffuser section (9) connected to the outside. The second stabilizing chamber (8) is connected to the first diffuser section (6). A second jet port (4) connected to the second ejection section is provided on the side wall of the second ejection section. A nozzle mechanism is provided at one end of the nozzle section (7) close to the second stabilizing chamber (8), the nozzle mechanism is provided with a nozzle, and the ejection chamber (10) is connected to the second stabilizing chamber (8) via the nozzle.

2. The composite ejector according to claim 1, characterized in that: A first nozzle (3) is provided at one end of the nozzle pipe extending into the first ejection section, and a first jet port (2) is provided at one end of the nozzle pipe located outside the installation cavity.

3. The composite ejector according to claim 1, characterized in that: The nozzle mechanism is a cylindrical structure arranged at one end of the nozzle section (7), a fluid channel is opened inside the cylindrical structure, and the fluid channel is connected to the second stabilizing chamber (8); A second nozzle (11) is obliquely provided on the side wall of the cylindrical structure, the inlet end of the second nozzle (11) is located in the injection cavity (10), and the outlet end of the second nozzle (11) is located in the second stabilizing chamber (8).

4. The composite ejector according to claim 3, characterized in that: At least one second nozzle (11) is provided, and a plurality of second nozzles (11) are distributed in a ring shape on the side wall of the cylindrical structure.

5. The composite ejector according to claim 3, characterized in that: The number of the second nozzles (11) is 2-16, and the incident angle of the second nozzles (11) is 2-40°.

6. The composite ejector according to claim 1, characterized in that: The nozzle mechanism is formed by a gap between an outer side wall of the nozzle section (7) and an inner side wall of the second ejection section, and the gap is a third nozzle (12).

7. The composite ejector according to claim 6, characterized in that: The third nozzle (12) is an annular nozzle, and the ejection chamber (10) is connected to the second stabilizing chamber (8) via the third nozzle (12).

8. The composite ejector according to claim 1, characterized in that: An end of the first diffuser section (6) close to the first stabilizing chamber (5) is a first inlet end, an end of the first diffuser section (6) close to the second stabilizing chamber (8) is a first outlet end, and an inner diameter of the first diffuser section (6) gradually increases from the first inlet end to the first outlet end; An end of the second diffuser section (9) close to the second flow stabilization chamber (8) is a second inlet end, an end of the second diffuser section (9) close to the outside is a second outlet end, and an inner diameter of the second diffuser section (9) gradually increases from the second inlet end to the second outlet end.

9. A method for using a composite ejector, based on the composite ejector according to any one of claims 1 to 8, characterized in that: The method of use comprises the following steps: A first fluid is introduced from the first jet port (2); the first fluid is accelerated by the first nozzle (3) and then mixed with the second fluid sucked into the injection port (1) through the first stabilizing chamber (5); the mixed fluid is a first mixed fluid; the first mixed fluid passes through the first stabilizing chamber (5) and reaches the first diffuser section (6); The third fluid sucked into the second jet port (4) is accelerated by a nozzle mechanism provided at one end of the nozzle section (7); the accelerated third fluid is mixed with the first mixed fluid from the first diffuser section (6) to form a second mixed fluid; the second mixed fluid enters the second diffuser section (9) through the second stabilizing chamber (8) and is output to the outside from the second outlet end of the second diffuser section (9).

10. A fuel cell system, characterized in that: The fuel cell system is installed with the composite ejector according to any one of claims 1 to 8.

Images