CN112058525A

CN112058525A - Nozzle with built-in rifling, ejector and fuel cell hydrogen circulation system

Info

Publication number: CN112058525A
Application number: CN202010896953.6A
Authority: CN
Inventors: 薛浩渊; 王雷; 贾磊; 张海伦
Original assignee: Shandong University
Current assignee: Shandong University
Priority date: 2020-08-31
Filing date: 2020-08-31
Publication date: 2020-12-11

Abstract

The invention discloses a nozzle with a built-in rifling, an ejector and a hydrogen circulation system of a fuel cell, which solve the problems in the prior art and have the advantages that the specific scheme is as follows: the nozzle with the built-in rifling comprises a nozzle body, wherein the nozzle body is conical, a plurality of rifling structures formed by grooves are arranged on the inner side surface of the nozzle body inside the nozzle body, the plurality of rifling structures are radially arranged, the nozzle is a tapered nozzle, a step is arranged on the inlet side of the nozzle body, the width of the grooves of the rifling structures is gradually reduced from the inlet of the nozzle to the outlet of the nozzle, or the nozzle is a tapered-tapered nozzle, and the nozzle is arranged on one side of the nozzle body and is provided with a reducing section which is coaxial with the nozzle body.

Description

Nozzle with built-in rifling, ejector and fuel cell hydrogen circulation system

Technical Field

The invention relates to the field of ejectors, in particular to a nozzle with a built-in rifling, an ejector and a fuel cell hydrogen circulation system.

Background

The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.

The ejector is a device integrating current collector injection, mixing and pressure boosting, and the working medium in the ejector can be gas or liquid. The ejector is widely applied to the fields of jet refrigeration, low-temperature multi-effect distillation seawater desalination, jet dedusting systems, fuel cells and the like.

The structure of the ejector mainly comprises a pump body and a nozzle structure, wherein the pump body mainly comprises a suction chamber, a mixing chamber and a pressure expansion chamber. The high-pressure fluid enters the nozzle of the ejector to be accelerated, and the speed of the fluid sprayed out of the nozzle can reach sonic speed or even supersonic speed.

The operating efficiency of the ejector is an important factor for restricting the energy consumption of the related system, and the improvement of the internal fluid mixing and the pressure boosting efficiency is an important direction for the optimal design of the ejector. The inventor finds that the conventional injector does not generate a fluid rotation effect perpendicular to the fluid advancing direction in the operation process, but only introduces a swirler or other rotating devices at the front end of the injector, so that the injector is bulky in structure, or adopts a simulation method in research to add rotating fluid, but the added swirler or other rotating devices certainly make the injector structure more complex, and only adds rotating fluid in simulation, but has no substantial effect on the actual flow of the injector fluid.

Conventional sprayers are difficult to adjust in size in use if subjected to the context of an application with limited available space.

Disclosure of Invention

In view of the defects in the prior art, a first object of the present invention is to provide a nozzle with a built-in rifling, which forms a plurality of rifling structures through grooves, and obtains high-speed fluid with a rotation effect at the nozzle outlet without integrating a swirler or other rotating fluid generating devices.

The second purpose of the invention is to provide an ejector, which improves the fluid mixing and pressure boosting efficiency of the ejector, reduces the energy consumption of an application system with the ejector, can obtain rotating high-speed fluid through the arrangement of a rifling structure, and improves the speed and the position of the fluid mixing completion in the ejector, so as to effectively shorten the length of a mixing chamber of the ejector, and enable the ejector to be more suitable for various application backgrounds with limited space.

The third purpose of the invention is to provide a hydrogen circulation system of a fuel cell, wherein the vacuum effect formed by high-speed gas can suck hydrogen which is not completely reacted at the anode of the proton exchange membrane fuel cell, and the energy consumption of the whole circulation system is reduced.

In order to achieve the purpose, the invention is realized by the following technical scheme:

the utility model provides a nozzle of built-in rifling, includes the nozzle body, and the nozzle body is inside to be the toper, and the nozzle body is inside along the medial surface of nozzle body, sets up many rifling structures that form through the recess, and many rifling structures are radial setting.

In the nozzle, the inner side surface of the nozzle body is provided with the plurality of rifling structures formed by the grooves, so that high-speed fluid with a rotating effect can be obtained at the outlet of the nozzle.

According to the nozzle with the built-in rifling, in order to guarantee the flow rate of fluid at the outlet of the nozzle, the depth of the grooves in the rifling structure is 2% -10% of the diameter of the outlet of the nozzle, the depth of the grooves at the inlet of the nozzle is set to be 5% -15% of the diameter of the inlet of the nozzle, and the width of the grooves is 2-4 times of the depth of the grooves.

The rifling-embedded nozzle is characterized in that 4 to 10 rifling structures are arranged.

A rifled nozzle as described above, the pitch of the rifled structure being from 2 to 8 times the length of the nozzle.

The nozzle with the built-in rifling is a tapered nozzle, the nozzle body is provided with a step on the inlet side of the nozzle, and the width of the grooves of the rifling structure is gradually reduced from the inlet of the nozzle to the outlet of the nozzle.

The nozzle with the built-in rifling is a tapered-diverging nozzle, a reducing section which is coaxial with the nozzle body is arranged on one side of the nozzle body, the inner diameter and the outer diameter of the reducing section are gradually reduced from one side to one side close to the inlet of the nozzle body, and a step is also arranged at one end, far away from the nozzle body, of the reducing section.

In a second aspect, the invention further provides an ejector, which comprises a first pipe, the first pipe is connected with a housing, the nozzle with the built-in rifling is arranged in the housing, a mixing chamber is arranged on one side of the housing, a mixing channel is arranged in the mixing chamber, an outlet of the nozzle is inserted into the mixing channel of the mixing chamber, a set distance is formed between the outlet of the nozzle and the minimum inner diameter of the mixing channel, and the speed and the position of the completion of the mixing of the fluid in the ejector can be increased by obtaining the rotating high-speed fluid, so that the length of the mixing chamber of the ejector is effectively shortened.

In the above injector, the housing is further provided with a second pipeline, the second pipeline is connected with the housing, and the second pipeline is arranged on one side of the nozzle.

In the ejector, a pressure expansion chamber is provided on a side of the mixing chamber away from the casing from the nozzle side, and a fluid passage in the pressure expansion chamber is flared.

In a third aspect, the invention further provides a hydrogen circulation system of a fuel cell, which comprises a hydrogen storage tank, wherein the hydrogen storage tank is connected with the ejector, the ejector is connected with the fuel cell stack, the fuel cell stack is connected with a gas-water separation device, and the gas-water separation device is connected with the ejector.

The beneficial effects of the invention are as follows:

1) according to the invention, the nozzle is provided with the plurality of rifling structures, the rifling structures are formed by the grooves, the grooves have set depth and width, and high-speed fluid with a rotation effect is obtained at the outlet of the nozzle on the premise of not integrating a swirler or other rotating fluid generating devices, so that the fluid in the nozzle is provided with cyclone, and the mixing efficiency of the fluid in the ejector is high.

2) According to the invention, high-speed fluid with cyclone is generated by the arrangement of the rifling structure, so that the mixing process can be rapidly completed on the premise of a shorter pump body structure, and the length of a mixing chamber in the ejector pump body is effectively shortened.

3) According to the invention, through the arrangement of the nozzle with the rifling structure arranged on the inner side, the fluid mixing and boosting efficiency of the ejector is improved, the energy consumption of an application system with the ejector is reduced, and the fluid mixing completion position of the corresponding ejector is closer to the front than that of the traditional ejector, so that the length of the ejector pump body can be designed to be shorter, and the volume occupied by the whole ejector is saved.

4) According to the invention, the nozzle with the rifling structure arranged on the inner side is adopted, the rotating air flow can achieve the self-cleaning effect in the ejector, the mixing efficiency is higher, and the energy is saved.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.

FIG. 1 is a general schematic diagram of an injector according to one or more embodiments of the present disclosure.

FIG. 2 is a side view of an injector convergent nozzle according to one or more embodiments of the present disclosure.

FIG. 3 is a half sectional view of an injector convergent nozzle in accordance with one or more embodiments of the invention.

FIG. 4 is a perspective view of one half of an injector convergent nozzle in accordance with one or more embodiments of the present disclosure.

FIG. 5 is a perspective view of an injector convergent-divergent nozzle in accordance with one or more embodiments of the present disclosure.

FIG. 6 is a side view of an injector convergent-divergent nozzle in accordance with one or more embodiments of the invention.

FIG. 7 is a perspective view of one half of an injector convergent-divergent nozzle in accordance with one or more embodiments of the present disclosure.

FIG. 8 is a schematic diagram of injector convergent-divergent nozzle simulation analysis in accordance with one or more embodiments of the present disclosure.

FIG. 9 is an axial tangential velocity vector projection of injector nozzle fluid according to one or more embodiments of the present disclosure.

FIG. 10 is a vector projection of axial tangential velocity of fluid in a conventional injector nozzle.

Figure 11 is a schematic diagram of a proton exchange membrane fuel cell hydrogen circulation loop according to one or more embodiments of the present invention.

In the figure: the spacing or dimensions between each other are exaggerated to show the location of the various parts, and the schematic is shown only schematically.

Wherein: 1. the device comprises a first pipeline, 2, an internal channel, 3, a suction chamber, 4, a mixing chamber, 5, a diffusion chamber, 6, a nozzle, 7, a second pipeline and 8, a third pipeline;

11. a hydrogen circulation ejector 12, a fuel cell stack 13, an oxygen circulation side inlet 14, a one-way valve 15, a gas-water separation device 16, an oxygen circulation side outlet,

17. nozzle inlet, 18, pumped fluid boundary, 19, pumped secondary flow, 20, nozzle internal flow, 21, mixing section flow, 22, flow in the diffusion chamber after mixing is complete.

Detailed Description

It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an", and/or "the" are intended to include the plural forms as well, unless the invention expressly state otherwise, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof;

for convenience of description, the words "up", "down", "left" and "right" in the present invention, if any, merely indicate correspondence with up, down, left and right directions of the drawings themselves, and do not limit the structure, but merely facilitate the description of the invention and simplify the description, rather than indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the invention.

Term interpretation section: the terms "mounted," "connected," "fixed," and the like in the present invention are to be understood in a broad sense, and for example, the terms "mounted," "connected," and "fixed" may be fixed, detachable, or integrated; the two components can be connected mechanically or electrically, directly or indirectly through an intermediate medium, or connected internally or in an interaction relationship, and the terms used in the present invention should be understood as having specific meanings to those skilled in the art.

As described in the background of the invention, the prior art has the problem of requiring a swirler before the injector, and in order to solve the technical problem, the invention provides a rifling-built nozzle, an injector and a hydrogen circulation system of a fuel cell.

Example one

In a typical embodiment of the present invention, referring to fig. 2, a nozzle with a built-in rifling includes a nozzle body, the nozzle body is tapered, and a plurality of rifling structures are arranged inside the nozzle body along an inner side surface of the nozzle body, the plurality of rifling structures are radially arranged along the inner side of the nozzle body, the radial rifling structures do not cause large resistance to fluid inside the nozzle, the fluid speed at the nozzle outlet has a large influence on the overall performance, and although the spiral structure of the coil type can realize air flow rotation, the resistance to rapid ejection of power fluid inside the nozzle is too large, which may reduce the performance of the ejector.

Further, the grooves are arranged in the nozzle body to form the rifling structure, so that effective airflow rotation can be formed at the nozzle outlet, and the rotation speed can reach about 50m/s when the pressure of the power fluid is 5 bar.

Referring to fig. 2-4, the nozzle is a convergent nozzle, generally, when the pressure of the fluid in the convergent nozzle meets the condition, the fluid velocity at the outlet can reach sonic speed, that is, mach 1, the nozzle body is provided with a step 18 at the inlet side of the nozzle, the nozzle body is conveniently mounted through the step 18, so that the outer step of the nozzle is a circular ring shape, the nozzle body is also conical, the size of the nozzle inlet 17 in the nozzle body is larger than that of the outlet side, that is, the width of the rifling structure groove is gradually reduced from the nozzle inlet to the nozzle outlet, and the outlet fluid rotates under the influence of the rifling result to form high-speed ejected and rotating fluid;

referring to fig. 5-7, the nozzle is a convergent-divergent nozzle, which is also called a laval nozzle, when the port pressure meets a set condition, the velocity of the internal fluid reaches sonic velocity at the throat of the nozzle, and the internal fluid continues to accelerate at the divergent section, and is ejected at supersonic velocity at the outlet, the velocity generally can reach mach 2 to mach 3, the nozzle is provided with a reducing section coaxially arranged with the nozzle body at one side of the nozzle body, the inner diameter and the outer diameter of the reducing section are gradually reduced from one side to the side close to the inlet of the nozzle body, and the reducing section is also provided with a step at the end far away from the nozzle body; in addition, in the convergent-divergent nozzle, the inner side of the nozzle body is divergent along with the nozzle body, the rifling structures are arranged in a radial shape, the arrangement direction of the rifling structures in the convergent nozzle is opposite to that of the rifling structures in the convergent nozzle, and under the influence of the rifling results, outlet fluid rotates to form fluid which is ejected at high speed and rotates.

In order to ensure the effect of air flow rotation, the depth of the grooves in the rifling structure is 2-10% of the diameter of the outlet of the nozzle, the depth of the grooves at the inlet of the nozzle is set to be 5-15% of the diameter of the inlet of the nozzle, and the width of the grooves is 2-4 times of the depth of the grooves.

The number of the rifling structures is 4-10, which is determined by different diameters of the outlet of the nozzle, the number of the rifling structures is insufficient, the air flow rotation acceleration capability is weak, the number of the rifling structures is too large, the resistance to the power fluid of the ejector is too large, and the performance is influenced.

Further, the winding distance of the rifling structure is the distance of the curve rotating for one circle, and is 2-8 times of the length of the nozzle, and after the structural parameters of the nozzle and the winding distance are determined, the winding angle of the rifling is determined immediately.

By means of the nozzles with the rifling structure arranged on the inside, an effective rotation of the gas stream is created at the nozzle outlet, which can reach about 50m/s at a power fluid pressure of 5 bar.

In some specific examples, the injector nozzle outlet diameter is 2.32 mm, the inlet diameter is 9.48 mm, the nozzle length is 31.78 mm, the nozzle outlet rifling groove depth is 0.26 mm, the groove width is 0.7 mm, the inlet rifling groove depth is 0.74 mm, the groove width is 2.6 mm, the wrap distance (the distance traveled by one revolution of the rifling) is 4 times the nozzle length, about 127 mm, and the wrap angle is about 5.37 °. Referring to fig. 8-10, the ejector efficiency improvement of the nozzle sized as described above may be about 8% -10% over conventional nozzles. For the ejector structure under different application backgrounds and different operation conditions, the parameters of the rifling in the nozzle need to be matched and designed.

It will of course be appreciated that other options are possible for the data of the injector nozzle.

Example two

Referring to fig. 1, the present embodiment provides an ejector, which includes a first pipe 1, one end of the first pipe is provided with a first fluid inlet, the other end of the first pipe is connected to a housing, a nozzle 6 according to the first embodiment is disposed inside the housing, the first pipe 1 is communicated with an internal channel 2 of the nozzle, one side of the housing away from the first pipe 1 is connected to a mixing chamber 4, the mixing chamber 4 is provided with a mixing channel communicated with the internal channel 2, from the nozzle side, the inner diameter of the mixing channel is reduced first, and then the set length is maintained, the length of the mixing channel is smaller than that of the nozzle, the mixing chamber 4 is provided with a pressure expansion chamber 5 on one side of the housing, and a fluid channel in the pressure expansion chamber is horn-shaped.

The nozzle outlet is inserted into the mixing channel of the mixing chamber and has a set distance from the minimum inner diameter of the mixing channel, which has a large impact on the performance of the injector and this distance value is related to the overall size of the injector, which in this embodiment is-2 mm-2mm, and it is understood that a step is provided in the housing for limiting the step of the nozzle in order to facilitate the installation of the nozzle.

Further, the shell is also provided with a second pipeline 7, the second pipeline 7 is vertical to the shell, and the second pipeline 7 is arranged on one side of the conical section of the nozzle, so that the fluid enters the space outside the nozzle through the second pipeline 7, because the nozzle is a conical nozzle, the fluid entering from the second pipeline 7 enters the suction chamber 3 to form a sucked secondary flow fluid 19, the fluid is mixed with the fluid entering from the first pipeline 1, namely the fluid 20 inside the nozzle at the mixing channel 5, the mixed fluid flows out from the outlet of the nozzle to form a mixed section fluid 21, and the mixed fluid rises in the diffusion chamber to form a fluid 22 in the diffusion chamber after mixing is completed, wherein the contact part of the second pipeline and the shell is a sucked fluid boundary 18.

In addition, a third duct 8 is provided on the side of the mixing chamber remote from the housing, the third duct 8 being used for connection to other devices, such as a firing cell stack.

The vacuum effect of the high velocity fluid in the suction chamber 3 draws the ejected fluid into the ejector and the two fluids mix in the ejector mixing chamber 4 and exit through the plenum 5, which also performs the pressure boosting effect.

EXAMPLE III

Referring to fig. 11, the hydrogen circulation system of a pem fuel cell includes a hydrogen circulation injector 11 (the injector described in the second embodiment), a fuel cell stack 12, a high-pressure hydrogen storage tank 10, a pressure regulating valve 9, and a gas-water separation device 15, where the high-pressure hydrogen storage tank, the pressure regulating valve, the hydrogen circulation injector, and the fuel cell stack are connected in sequence, the fuel cell stack has an oxygen circulation side inlet 13 and an oxygen circulation side outlet 16, and the fuel cell stack is a pem fuel cell stack, an anode of the fuel cell stack is connected to the gas-water separation device, and the gas-water separation device is connected to the hydrogen circulation injector 11 and a check valve 14, respectively.

The gas-water separator 15 is a common gas-water separator.

In a proton exchange membrane fuel cell system, a hydrogen circulation ejector mainly plays two roles, 1, hydrogen is supplied to a proton exchange membrane and unreacted hydrogen is circulated; 2. providing a boost function for the circulation system.

The proton exchange membrane fuel cell takes hydrogen as fuel, air or pure oxygen as oxidant, graphite or surface modified metal plate with gas flow channel is bipolar plate, during operation, hydrogen in high pressure hydrogen storage tank 10 enters bipolar plate of fuel cell stack 12 through pressure reducing valve 9 and ejector 11, and respectively reaches anode of fuel cell stack 12 through gas guide channel of bipolar plate, oxygen enters cathode through gas guide channel at oxygen circulation side inlet 13, reaction gas reaches reaction active center of electrode catalyst layer through diffusion layer on electrode, hydrogen dissociates into hydrogen ion (proton) and electron with negative electricity under action of anode catalyst, hydrogen ion migrates from one sulfonic group to another sulfonic group in proton exchange membrane in form of hydrated proton H +, finally reaches cathode, and proton conduction is realized.

This migration of protons results in a negatively charged electron accumulation at the anode, which becomes a negatively charged terminal (negative). At the same time, oxygen molecules at the cathode react with the electrons to become oxygen ions under the action of the catalyst, causing the cathode to become a positively charged terminal (positive electrode), creating a voltage between the negative terminal of the anode and the positive terminal of the cathode. In the power generation process, incompletely reacted hydrogen is recycled through a hydrogen circulation loop, passes through a gas-water separation device 15 and enters a hydrogen circulation ejector 11 to form injected hydrogen, the hydrogen is mixed with rotating gas ejected by a nozzle and then enters the anode of the fuel cell stack again, liquid separated by the gas-water separation device can flow into a liquid storage tank or other equipment through a one-way valve 14, and incompletely reacted oxygen is discharged through an oxygen circulation side outlet 16.

The operating principle of the hydrogen circulation loop of the fuel cell is as follows: the hydrogen in the high-pressure hydrogen storage tank 10 enters the ejector nozzle 2 through the pipeline 1 to accelerate, the speed of the hydrogen ejected from the nozzle can reach the sonic speed, the vacuum action formed by high-speed gas can suck the hydrogen which is not completely reacted at the anode of the proton exchange membrane fuel cell, the high-speed hydrogen and the unreacted hydrogen in the high-pressure hydrogen storage tank 10 are mixed in the ejector mixing chamber 4 and enter the anode to react, and the boosting action of the hydrogen is completed through the hydrogen circulating ejector.

The nozzle is arranged in the ejector, so that the hydrogen can rotate after entering the nozzle, the mixing efficiency of the rotating gas sprayed by the nozzle and the injected hydrogen is higher, the mixing completion speed is higher, and the purposes of energy conservation and consumption reduction can be achieved. Meanwhile, because the rotating gas flow can enable the fluid mixing completion position to be moved forward, in some examples, the length of the mixing chamber of the ejector can be shortened, so that the ejector is smaller in size and easier to integrate into a hydrogen circulation system of the fuel cell.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The nozzle with the built-in rifling is characterized by comprising a nozzle body, wherein the inside of the nozzle body is conical, a plurality of rifling structures formed by grooves are arranged on the inner side surface of the nozzle body, and the plurality of rifling structures are arranged in a radial mode.

2. The rifling built-in nozzle of claim 1, wherein the depth of the grooves in the rifling structure is 2-10% of the diameter of the nozzle outlet, the depth of the grooves at the nozzle inlet is set to be 5-15% of the diameter of the nozzle inlet, and the width of the grooves is 2-4 times the depth of the grooves.

3. A rifled nozzle according to claim 1, wherein the number of said rifling structures is 4 to 10.

4. A rifled nozzle according to claim 1, wherein the pitch of the rifling pattern is 2 to 8 times the length of the nozzle.

5. The rifled nozzle of claim 1, wherein said nozzle is a convergent nozzle, said nozzle body having a step on the inlet side of the nozzle, said grooves of said rifling pattern having a width that gradually decreases from the inlet side of the nozzle to the outlet side of the nozzle.

6. The rifled nozzle of claim 1, wherein said nozzle is a convergent-divergent nozzle, and wherein said nozzle has a reduced diameter section coaxially disposed with said nozzle body at one side of said nozzle body, wherein said reduced diameter section has an inner diameter and an outer diameter both decreasing from one side to a side near an inlet of said nozzle body, and wherein said reduced diameter section is also stepped at an end remote from said nozzle body.

7. An injector comprising a first conduit connected to a housing in which a rifled nozzle according to any one of claims 1 to 6 is disposed, a mixing chamber disposed on one side of the housing, a mixing channel disposed in the mixing chamber, a nozzle outlet inserted into the mixing channel of the mixing chamber, and the nozzle outlet being at a set distance from the smallest internal diameter of the mixing channel.

8. An injector as claimed in claim 7 wherein the housing is further provided with a second conduit connected to the housing and provided to one side of the nozzle.

9. An injector as claimed in claim 7 wherein, starting from the nozzle side, the mixing chamber is provided with a pressure-expanding chamber on the side remote from the housing, the flow passage in the pressure-expanding chamber being flared.

10. A fuel cell hydrogen circulation system comprising a hydrogen storage tank connected to an injector according to any one of claims 7 to 9, the injector being connected to a fuel cell stack, the fuel cell stack being connected to a gas-water separation device, the gas-water separation device being connected to the injector.