Multi-nozzle ejector of self-adaptive hydrogen fuel cell system and self-adaptive method

Abstract

The invention discloses a multi-nozzle ejector of a self-adaptive hydrogen fuel cell system. The multi-nozzle ejector comprises an ejector main body, a flow control valve, a flow sensor and a main controller, a working flow channel of the ejector main body comprises a plurality of sub-channels, and each sub-channel is controlled by a flow control valve and is provided with a nozzle; the cross section, perpendicular to the axial direction, of the nozzle is of a multi-star-shaped structure formed by connecting a plurality of V shapes; the flow sensor is used for detecting the flow of workflow, and the main controller is used for receiving detection signals of the flow sensor and driving the flow control valves to control the flow of the corresponding nozzles so as to be matched with the output power change of the fuel cell system. The invention further discloses a self-adaption method of the system. The multi-nozzle ejector disclosed by the invention has relatively strong compatibility to complex and changeable working conditions of the fuel cell, the mixing performance and the stability and the reliability of the fuel cell are improved, and the working range of the ejector is widened.

Description

Technical Field

[0001] The present invention belongs to the technical field of fuel cells, and in particular relates to a multi-nozzle ejector and an adaptive method of an adaptive hydrogen fuel cell system. Background Art

[0002] Hydrogen fuel cells are a typical electrochemical device that directly converts the chemical energy of clean energy hydrogen into electrical energy. They have the advantages of being clean, high energy density, high energy conversion rate and renewable. In recent years, they have been rapidly developed in the automotive industry and are particularly suitable for use in the field of hydrogen fuel cell heavy trucks. In order to maintain the stable and efficient operation of hydrogen fuel cells and purge the accumulated water in the anode flow channel, hydrogen is usually transported to the anode at a certain excess stoichiometric ratio in actual operation. In order to improve the utilization rate of hydrogen fuel and reduce safety hazards, the reuse of unreacted hydrogen at the anode outlet through a hydrogen recycling system is crucial to improving the power and economy of hydrogen fuel cells.

[0003] A hydrogen ejector is a hydrogen recovery device that uses a high-energy jet of high-pressure working hydrogen to form a low-pressure area near the nozzle to entrain and mix the unreacted hydrogen. It has the advantages of simple structure, reliable operation, and no parasitic power. However, ejectors with traditional structures have defects such as a narrow working range, poor hydrogen recovery effect in the low-power working area, and large fluctuations in hydrogen supply pressure. These defects can easily cause frequent fluctuations in the anode / cathode differential pressure of hydrogen fuel cells, leading to rupture of the proton exchange membrane, which greatly affects the life and reliability of hydrogen fuel cells. In addition, traditional ejectors can only meet specific design conditions and cannot be applied to changes in multiple operating conditions of fuel cells, and they cannot adapt to changes in the output power of fuel cells. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a multi-nozzle ejector and an adaptive method for an adaptive hydrogen fuel cell system.

[0005] In order to achieve the above purpose, the technical solution of the present invention is:

[0006] A multi-nozzle ejector for an adaptive hydrogen fuel cell system, comprising an ejector body, a flow control valve, a flow sensor and a main controller; the ejector body comprises a working flow channel, a reflux suction channel, a reflux suction chamber, a normal pressure mixing chamber, a pressure diffuser chamber and a mixed flow channel, the working flow channel, the reflux suction chamber, the normal pressure mixing chamber, the pressure diffuser chamber and the mixed flow channel are sequentially connected along the axial direction, and the reflux suction channel is connected to the reflux suction chamber on one side of the working flow channel; the working flow channel comprises a plurality of sub-channels, each of which is controlled by a flow control valve and is provided with a nozzle; the cross-section of the nozzle perpendicular to the axial direction is a multi-star structure formed by a plurality of V-shaped connections, and the area of ​​the cross-section gradually decreases towards the side of the reflux suction chamber; the flow sensor is used to detect the flow of the working flow, and the main controller is used to receive the detection signal of the flow sensor and drive each flow control valve to control the flow of the corresponding nozzle to match the output power change of the fuel cell system.

[0007] Optionally, the number of the nozzles is 2 to 4.

[0008] Optionally, in the multi-star structure formed by the multiple V-shaped connections, the number of V-shapes is 5 to 9.

[0009] Optionally, the number of the V-shapes is 8, wherein the internal angle of each V-shape is 54.88°, and the angle between two V-shapes is 94.88°.

[0010] Optionally, the inlet of the nozzle is circular, and the outlet is the multi-star structure, wherein the circular diameter of the inlet is 10-18 mm, and the circumscribed circle diameter of the outlet is 3-8 mm.

[0011] Optionally, the length of the nozzle in the axial direction ranges from 37 mm to 47 mm.

[0012] Optionally, the plurality of nozzles are arranged around an axis of the reflux suction chamber.

[0013] Optionally, a pressure sensor for detecting the outlet pressure of the mixed flow channel is further included, and the pressure sensor is connected to the main controller by signal.

[0014] A hydrogen fuel cell system comprises the multi-nozzle ejector of the adaptive hydrogen fuel cell system.

[0015] An adaptive method for a multi-nozzle ejector of the above-mentioned adaptive hydrogen fuel cell system comprises:

[0016] a) Set the initial opening of each flow control valve according to the target flow value;

[0017] b) the working flow hydrogen enters the multi-nozzle ejector, and the working flow is collected by the flow sensor;

[0018] c) The main controller determines the difference between the current flow value and the target flow value based on the working flow, calculates the adjustment amount and dynamically adjusts the opening of each flow control valve.

[0019] The beneficial effects of the present invention are:

[0020] The multi-nozzle mode can switch the flow opening of each nozzle by adaptively matching the fuel cell operating conditions, thereby meeting the reflux requirements of fuel cells with different output powers and expanding the working range of the ejector; the use of a V-shaped nozzle can enhance the shear effect of the working flow and reflux and improve the mixing performance, thereby generating regular longitudinal vortices, increasing the speed of the working flow, thereby generating a larger pressure difference, inhaling more reflux gas, improving the ejector performance and improving the power performance and economic performance of the hydrogen fuel cell.

[0021] Other features and advantages of the present invention will be set forth in the following description, and in part will be apparent from the description, or may be learned by practicing the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic diagram of a multi-nozzle ejector of an adaptive hydrogen fuel cell system of an embodiment;

[0023] Figure 2 Schematic diagram of the flow path of the ejector body of the embodiment;

[0024] Figure 3 Schematic diagram of the exploded structure of the ejector body of the embodiment;

[0025] Figure 4 is a schematic diagram of the cross-sectional structure of the ejector body of the embodiment;

[0026] Figure 5 Schematic diagram of the structure of the nozzle device of the ejector body of the embodiment (inlet end);

[0027] Figure 6 It is a structural schematic diagram of the nozzle device of the ejector body of the embodiment (exit end);

[0028] Figure 7 Schematic diagram of a multi-nozzle ejector used in a hydrogen fuel cell system according to an embodiment

[0029] Figure 8 Flow chart of an adaptive method for a multi-nozzle ejector adaptive hydrogen fuel cell system according to an embodiment. DETAILED DESCRIPTION

[0030] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments. The various drawings of the present invention are only for illustration to make it easier to understand the present invention, and the specific proportions can be adjusted according to design requirements. The upper and lower relationships of the relative elements and the definitions of the front / back in the figures described in the text should be understood by those skilled in the art to refer to the relative positions of the components, so they can all be flipped to present the same components, which should all fall within the scope disclosed in this specification.

[0031] The multi-nozzle ejector of the adaptive hydrogen fuel cell system of the embodiment is used to mix the unreacted hydrogen at the anode outlet, the water vapor produced by the reaction and the hydrogen supplied from the hydrogen cylinder during the operation of the fuel cell, so as to improve the hydrogen utilization rate and improve the water balance inside the fuel cell to stabilize the operation of the fuel cell. It can automatically switch the flow opening of the working nozzle according to the change of the fuel cell output power, so as to improve the suction performance of the ejector under different output powers of the fuel cell.

[0032] refer to Figures 1 to 4 The multi-nozzle ejector of the embodiment includes an ejector body 1, a flow control valve 2, a flow sensor 3 and a main controller 4. The ejector body 1 includes a working flow channel a, a reflux suction channel b, a reflux suction chamber c, a normal pressure mixing chamber d, a pressure diffusion chamber e and a mixed flow channel f. The working flow channel a, the reflux suction chamber c, the normal pressure mixing chamber d, the pressure diffusion chamber e and the mixed flow channel f are sequentially connected along the axial direction (x direction in the figure), and the reflux suction channel b is connected to the reflux suction chamber c on one side of the working flow channel a. The working flow channel a includes a plurality of sub-channels, each of which is controlled by a flow control valve 2 and is provided with a nozzle 141. The flow sensor 3 is arranged at the entrance of the working flow channel a for detecting the flow rate of the working flow. The main controller 4 is used to receive the detection signal of the flow sensor 3 and drive each flow control valve 2 to control the flow rate of the corresponding nozzle 141 to match the output power change of the fuel cell system.

[0033] refer to Figure 3-4To construct the above-mentioned flow path, the ejector body 1 includes a working flow inlet 11, a first fixing member 12, a second fixing member 13, a nozzle device 14, a nozzle valve body 15, an upper frame 16, a lower frame 17, a mixing chamber member 18 and a mixing flow outlet 19. The nozzle device 14 is assembled in the nozzle valve body 15, one side of which is connected and fixed to the working flow inlet 11 through the first fixing member 12 and the second fixing member 13, and the other side is connected and fixed to the mixing chamber member 18, and the end of the mixing chamber member 18 is fixed to the mixing flow outlet 19 through the sealing ring 10. The upper frame 16 and the lower frame 17 fix the nozzle valve body 15 and the mixing chamber member 18 therein from the upper and lower sides, and the two ends are respectively fixed to the second fixing member 13 and the mixing flow outlet 19. The working flow inlet 11 and the nozzle device 14 are used to form the working flow channel a, the mixing cavity body 18 is used to form the normal pressure mixing cavity d and the pressure diffusion cavity e, the mixed flow outlet 19 is used to form the mixed flow channel f, and the lower frame 17 is used to form the reflux suction channel b and form the reflux suction chamber c through the cooperation of various components. In addition, the mixed flow outlet 19 is also provided with a pressure sensor 5, which is connected to the main controller 4 for signal detection of back pressure to prevent reflux caused by excessive pressure at the mixed flow outlet.

[0034] The nozzle device 14 is provided with a plurality of nozzles 141, for example, 2 to 4 nozzles. This embodiment is described by taking 4 nozzles as an example. Figure 5 and Figure 6 , the cross section of the nozzle 141 perpendicular to the axis is a multi-star structure formed by connecting multiple V-shaped structures, and the area of ​​the cross section gradually decreases towards the side close to the reflux suction chamber c. In the multi-star structure formed by the above-mentioned multiple V-shaped connections, the number of V-shapes is 5 to 9. In one embodiment, the inlet 141a of the nozzle 141 is circular, the outlet 141b is the above-mentioned multi-star structure, and the number of V-shapes is 8, the internal angle α of each V-shape is 54.88°, and the angle β between the two V-shapes is 94.88°. The circular diameter of the inlet 141a is 10 to 18 mm, and the diameter of the circumscribed circle of the outlet 141b is 3 to 8 mm. More specifically, the diameter of the nozzle inlet circle is 14 mm, the diameter of the circumscribed circle of the nozzle outlet multi-star structure is 5 mm, and the side length of the V-shaped structure is 1 mm. The inner diameter of the normal pressure mixing chamber d is 16 mm, and the inner diameter of the outlet end of the diffusion chamber e is 33.5 mm. The length range of the nozzle device 14 in the axial direction is 37 mm-47 mm. The four nozzles 141 are arranged around the axis of the reflux suction chamber c.

[0035] The primary flow (working flow) hydrogen enters the nozzle 141 from the inlet 141a and enters the reflux suction chamber c from the outlet 141b, and the reflux gas enters the reflux suction chamber c from the reflux suction channel b. The multi-star structure nozzle formed by the above-mentioned multiple V-shaped connections can improve the entrainment ratio on the one hand, and reduce the pressure loss on the other hand, which plays an important role in improving the mixing performance of the working gas and the ejection gas, increasing the ejection effect, and forming a uniform and stable mixed fluid, so as to solve the technical problems in the prior art that the hydrogen ejector has poor compatibility with the complex and changeable working conditions of the fuel cell, poor mixing performance, and low stability and reliability of the fuel cell.

[0036] For improving the entrainment ratio: 1) The V-shape induces local high-speed turbulence and longitudinal vortex when hydrogen passes through. The generation of this flow phenomenon will accelerate the speed of the primary flow hydrogen, thereby reducing the pressure of the reflux suction chamber c and the atmospheric mixing chamber d. At this time, a negative pressure area will even be formed at the entrance of the reflux suction chamber c and the atmospheric mixing chamber d, increasing the pressure difference between the reflux suction channel b and the reflux suction chamber c, so that more reflux gas is entrained into the ejector, improving the entrainment performance of the ejector. Due to the generation of high-speed turbulence, the fluid boundary layer will separate at this turbulence generation site, and when the boundary layer reattaches, it will cause new entrainment flow. 2) Compared with traditional nozzles, nozzles with multiple V shapes have a larger circumference and a larger surface area. This advantage can increase the contact area between the nozzle and the fluid, thereby promoting the momentum and energy exchange between the two fluids. Its geometric structure will break the symmetry of the fluid flow, making the ejection area more uniform, avoiding the formation of fluid retention areas, and thus improving the overall entrainment effect. In addition, the geometric structure of the nozzle 141 will enhance the shearing effect between the primary flow and the return flow, so that more return flow gas is sucked into the ejector. 3) The V-shaped sharp corner portion can accelerate the flow rate and further reduce the local static pressure. The optimized pressure gradient can effectively drive the return flow gas into the ejector and enhance the suction effect of the ejector.

[0037] For reducing pressure loss: 1) The nozzle with multiple V shapes avoids sudden changes in local cross-sectional area through gradual changes in cross-sectional area, avoiding eddy loss caused by sudden changes in cross-sectional area. The sharp corners of the V shape can guide the fluid to be evenly distributed in multiple directions, reducing turbulent losses caused by flow concentration in a single direction. 2) The nozzle with multiple V shapes will cause the fluid to re-attach to the nozzle surface, reduce the thickness of the boundary layer, and reduce the pressure loss caused by friction. 3) The cross-section of the nozzle with multiple V shapes allows the pressure to be distributed along the cross-section, avoiding the formation of local high-pressure points and making the pressure drop stable.

[0038] refer to Figure 7The application of multi-nozzle ejector in hydrogen fuel cell system, the whole structure includes hydrogen tank, air intake valve, proportional valve, flow control valve, ejector body, flow sensor, hydrogen fuel cell, water-gas separator, pressure relief valve and tail exhaust valve, etc. The working flow inlet 11 is used to receive hydrogen after passing through the pressure reducing valve, and form a low-pressure area at its outlet after passing through the nozzle 141 to inhale the gas at the anode outlet of the fuel cell connected to the reflux suction channel b. The two gases are mixed in the normal pressure mixing chamber d, and are sent to the fuel cell through the mixing flow channel f after the speed is reduced in the diffusion chamber e. The opening degree of each nozzle 141 is determined by the output power of the fuel cell. For details, refer to Figure 8 , the adaptive method of the multi-nozzle ejector of the adaptive hydrogen fuel cell system includes:

[0039] a) Set the initial opening of each flow control valve according to the target flow value;

[0040] b) The working flow hydrogen enters the multi-nozzle ejector, and the working flow is collected by a flow sensor;

[0041] c) The main controller determines the difference between the current flow value and the target flow value based on the working flow, calculates the adjustment amount and dynamically adjusts the opening of each flow control valve, thereby controlling the flow and shutoff of each nozzle, achieving stepless regulation that accurately matches the flow changes.

[0042] The main controller may include a data acquisition module for filtering and calibrating the signal output by the flow sensor and converting it into a flow value. The main controller receives the signal of the flow sensor, executes the control algorithm and drives the flow control valve. The flow control valve is preferably an electric valve. For example, a feedback-based control algorithm (PID control) is used to dynamically adjust the opening of the valve according to the error between the target flow (set value) and the actual flow (sensor measurement value). Conventionally, it also includes a power supply system to ensure the operation of the system, which will not be elaborated.

[0043] The above embodiments are only used to further illustrate a multi-nozzle ejector and adaptive method of an adaptive hydrogen fuel cell system of the present invention, but the present invention is not limited to the embodiments. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A multi-nozzle ejector for an adaptive hydrogen fuel cell system, characterized in that: It includes an ejector body, a flow control valve, a flow sensor and a main controller; the ejector body includes a working flow channel, a reflux suction channel, a reflux suction chamber, a normal pressure mixing chamber, a pressure diffuser chamber and a mixed flow channel, the working flow channel, the reflux suction chamber, the normal pressure mixing chamber, the pressure diffuser chamber and the mixed flow channel are connected in sequence along the axial direction, and the reflux suction channel is connected with the reflux suction chamber on one side of the working flow channel; the working flow channel includes a plurality of sub-channels, each of which is controlled by a flow control valve and is provided with a nozzle; the cross-section of the nozzle perpendicular to the axial direction is a multi-star structure formed by a plurality of V-shaped connections, and the area of ​​the cross-section gradually decreases towards the side of the reflux suction chamber; the flow sensor is used to detect the flow of the working flow, and the main controller is used to receive the detection signal of the flow sensor and drive each flow control valve to control the flow of the corresponding nozzle to match the output power change of the fuel cell system.

2. The multi-nozzle ejector of the adaptive hydrogen fuel cell system according to claim 1, characterized in that: The number of the nozzles is 2 to 4.

3. The multi-nozzle ejector of the adaptive hydrogen fuel cell system according to claim 1, characterized in that: In the multi-star structure formed by the multiple V-shaped connections, the number of the V-shaped structures is 5 to 9.

4. The multi-nozzle ejector of the adaptive hydrogen fuel cell system according to claim 3, characterized in that: The number of the V-shapes is 8, wherein the internal angle of each V-shape is 54.88°, and the angle between two V-shapes is 94.88°.

5. The multi-nozzle ejector of the adaptive hydrogen fuel cell system according to claim 1, characterized in that: The inlet of the nozzle is circular, and the outlet is the multi-star structure, wherein the circular diameter of the inlet is 10-18 mm, and the circumscribed circle diameter of the outlet is 3-8 mm.

6. The multi-nozzle ejector of the adaptive hydrogen fuel cell system according to claim 5, characterized in that: The length of the nozzle in the axial direction ranges from 37 mm to 47 mm.

7. The multi-nozzle ejector of the adaptive hydrogen fuel cell system according to claim 1, characterized in that: The plurality of nozzles are arranged around an axis of the backflow suction chamber.

8. The multi-nozzle ejector of the adaptive hydrogen fuel cell system according to claim 1, characterized in that: It also includes a pressure sensor for detecting the outlet pressure of the mixed flow channel, and the pressure sensor is connected to the main controller by signal.

9. A hydrogen fuel cell system, characterized in that: A multi-nozzle ejector for an adaptive hydrogen fuel cell system comprising any one of claims 1 to 8.

10. An adaptive method for a multi-nozzle ejector of an adaptive hydrogen fuel cell system according to claim 1, characterized in that: include: a) Set the initial opening of each flow control valve according to the target flow value; b) the working flow hydrogen enters the multi-nozzle ejector, and the working flow is collected by the flow sensor; c) The main controller determines the difference between the current flow value and the target flow value based on the working flow, calculates the adjustment amount and dynamically adjusts the opening of each flow control valve.

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