WO2022252072A1

WO2022252072A1 - Fluid circulation device, fuel cell system and operating method of fluid circulation device

Info

Publication number: WO2022252072A1
Application number: PCT/CN2021/097467
Authority: WO
Inventors: Xu Han
Original assignee: Schaeffler Technologies AG & Co. KG
Priority date: 2021-05-31
Filing date: 2021-05-31
Publication date: 2022-12-08

Abstract

A fluid circulation device includes a jet input path (11), a diversion input path (10), a nozzle (5), a mixing chamber (6) located downstream of the nozzle (5) and connected to the diversion input path (10), and a diffusion chamber (7) and a mixed fluid output path (9) successively located downstream of the mixing chamber (6); the jet input path (11) includes a first channel (2) at an inner housing (3) and a second channel (12) constructed at a shaft (13); the inner housing (3) has a cylindrical inner cavity and the shaft (13) is disposed in the inner cavity; and the fluid circulation device further includes an electric motor (1), which can drive the shaft (13) to rotate with respect to the inner housing (3), so that the first channel (2) and the second channel (12) are connected, partially connected or disconnected. A fuel cell system includes a stack and the above fluid circulation device.

Description

FLUID CIRCULATION DEVICE, FUEL CELL SYSTEM AND OPERATING METHOD OF FLUID CIRCULATION DEVICE

TECHNICAL FIELD

The disclosure relates to a technical field of fuel cell, and in particular to a fluid circulation device, a fuel cell system and an operating method of a fluid circulation device in a fuel cell system.

BACKGROUND

In operation of a fuel cell, hydrogen gas with a certain pressure, flow rate and humidity must be supplied. For the flow rate of hydrogen, a stoichiometric ratio is required to exceed 1.0 in most fuel cell systems; and therefore, hydrogen recirculation is very important for improving efficiency.

In existing fuel cell systems, there are many types of hydrogen circulation loop designs.

In a design scheme, a hydrogen circulation pump can be provided in a hydrogen circulation subsystem, so as to realize recycling of hydrogen gas at an anode outlet of a fuel cell stack, i.e., at a hydrogen outlet. However, the hydrogen circulation pump will additionally generate a large amount of energy consumption during operation. Moreover, the hydrogen circulation pump has a high cost even in mass production.

In another design scheme, an ejector can be provided in the hydrogen circulation subsystem. For a passive ejector, it has a simple structure, but cannot cover an entire working range of a fuel cell system. Specifically, the passive ejector can only achieve a good ejection effect at a high power and a high flow rate; while at a low power and a low flow rate, it has a poor ejection effect, and even cannot achieve a sufficient hydrogen circulation volume. There are also ejectors equipped with solenoid valves, which can cover the entire working range through pulse control, but will generate noise.

In a design scheme of a combination of the hydrogen circulation pump and the ejector, for example, as described in Chinese Patent Application CN110247083A, higher requirements are put forward for matching and controlling of the hydrogen circulation pump and the ejector, and its cost will be very high.

SUMMARY

Therefore, an object of the disclosure is to provide a fluid circulation device that can be used in a fuel cell system, which can cover a full power range of a stack in the fuel cell system and has a lower cost.

One aspect of the above object is achieved by a fluid circulation device, which includes a jet input path, a diversion input path, a nozzle constructed at an outlet of the jet input path, a mixing chamber located downstream of the nozzle and connected to the diversion input path, and a diffusion chamber and a mixed fluid output path successively located downstream of the mixing chamber. In this case, the jet input path includes an upstream first channel constructed at an inner housing and a second channel constructed at a shaft, wherein the inner housing has a cylindrical inner cavity and the shaft is disposed in the inner cavity. The fluid circulation device further includes an electric motor, which can drive the shaft to rotate with respect to the inner housing, so that the first channel and the second channel are connected, partially connected or disconnected.

The fluid circulation device provided here can be particularly arranged in a fluid circulation loop. The fluid circulation device includes two input paths, i.e., a jet input path and a diversion input path. The jet input path can be directly or indirectly connected to a fluid source, such as a hydrogen storage tank in a hydrogen circulation loop of a fuel cell system, and thereby newly supplied fluid can be delivered to an inlet of the jet input path. The diversion input path can be directly or indirectly connected to a component for providing recycled fluid, such as a hydrogen outlet of a stack of the fuel cell system, and thereby the fluid to be recycled can be delivered to an inlet of the diversion input path.

In this case, in the fluid circulation device, the jet input path has two sections, i.e., a first channel and a second channel are respectively constructed at different components, i.e. at an inner housing having a cylindrical inner cavity and at a shaft, so that the shaft can be driven by the electric motor to controllably rotate with respect to the inner housing, which can thereby reliably and easily adjust the relative position of the first channel and the second channel, i.e. a connecting-disconnecting state of the jet input path.

According to a control strategy of the electric motor, the fluid circulation device can provide two operating modes.

In one operating mode, the fluid circulation device serves as a proportional valve. Then, the shaft can be driven by the motor to rotate with respect to the inner housing, which adjusts an overlap rate of the outlet of the first channel at the inner housing and the inlet of the second channel at the shaft, thereby controlling an opening rate of the proportional valve. Therefore, according to requirements of a system in which the fluid circulation device is disposed, a fluid with a required flow rate can be provided through the jet input path, and the fluid then flows through the nozzle, the mixing chamber, the diffusion chamber and the mixed fluid output path, and then enters downstream components of the fluid circulation device.

In another operating mode, the fluid circulation device serves as an ejector. Then, the shaft can be driven by the electric motor to quickly rotate in one circumferential direction or to alternately rotate (i.e., swing) in two circumferential directions, so that the first channel at the inner housing can be connected to the second channel at the shaft at a required frequency, which thereby provides a pulsed jet at a required frequency. Accordingly, a fluid at a high pressure which is input through the jet input path can be injected into the mixing chamber through the nozzle as a main flow. In this case, a recycled fluid at a low pressure will be sucked into the mixing chamber via the diversion input path as a secondary flow. Subsequently, the fluids mixed in the mixing chamber can be decelerated and pressurized in the diffusion chamber and output from the mixed fluid output path, and then enter the downstream components of the hydrogen circulation loop.

In a preferred embodiment, the first channel is constructed as a through hole that passes through an outer circumferential surface and an inner circumferential surface of the inner housing. Preferably, the first channel is constructed as a through hole extending in an axial direction. Alternatively, the first channel is constructed as a through hole extending in a direction slightly angled from the axial direction.

Preferably, the second channel includes a first section and a second section connected to each other, wherein the first section at least partially extends in a radial direction and is connected to the first channel, and the second section extends in an axial direction and is connected to the nozzle. The term “at least partially extends in a radial direction” herein can be understood as: extending in the radial direction or extending in a direction slightly angled from the radial direction. In this case, as a preferred design, when the first channel and the second channel are fully connected, the first channel and the first section of the second channel extend in a same direction.

In another preferred embodiment, the nozzle is integrally constructed at an axial end of the inner housing. In this case, preferably, the nozzle is disposed coaxially with the cylindrical inner cavity of the inner housing. Then, the structure of the fluid circulation device can be simplified.

Preferably, the fluid circulation device includes an outer housing, wherein the outer housing is disposed to surround an axial end of the inner housing which is provided with the nozzle to form the diversion input path, and the outer housing forms the mixing chamber, the diffusion chamber and the mixed fluid output path. In this case, the outer housing can be particularly constructed in a form of a venturi tube. Preferably, the outer housing and the inner housing are disposed coaxially, thus the outlet of the jet input path, the nozzle, the mixing chamber, and the diffusion chamber are sequentially disposed on a same axis along a flow direction of the fluid. The fluid circulation device thus constructed has a simple structure and can be easily implemented.

In a favorable embodiment, the electric motor can directly drive the shaft to rotate.

In an alternative and favorable embodiment, a speed change mechanism is disposed between the electric motor and the shaft. In this case, the speed change mechanism is preferably a reducer. Advantageously, the speed change mechanism is constructed as a gear transmission mechanism, such as a planetary gear transmission mechanism. Advantageously, the speed change mechanism is constructed as a belt drive mechanism. Thus, a rotational motion output by the electric motor can preferably be transferred to the shaft in a speed change manner according to operating environment of the fluid circulation device, such as requirements of a fuel cell system.

In this case, when there is a speed change mechanism, the electric motor and the shaft are disposed coaxially or parallel to each other. Thus, the fluid circulation device can be flexibly constructed according to the operating environment of the fluid circulation device, such as the structure of the fuel cell system.

Another aspect of the above object is achieved by a fuel cell system. The fuel cell system includes a stack and the above fluid circulation device. Preferably, the jet input path of the fluid circulation device can be connected to a hydrogen storage container in the fuel cell system, and the diversion input path of the fluid circulation device can be connected to a hydrogen outlet of the stack of the fuel cell system.

Another aspect of the above object is achieved by an operating method of a fluid circulation device in a fuel cell system. In the operating method, when the stack is operated at a medium to high power, the fluid circulation device serves as a proportional valve; and when the stack is operated at a low power, the fluid circulation device serves as an ejector.

In this case, the case where the stack is operated at the medium to high power is for example a case where the stack operated at a power 25%or more of a full power; and accordingly, the case where the stack is operated at the low power is for example a case where the stack operated at a power below 25%of the full power.

In this case, when the fluid circulation device serves as the proportional valve, the shaft can be driven by the electric motor to rotate with respect to the inner housing, which adjusts an opening rate of the proportional valve, i.e., an overlap rate of the outlet of the first channel at the inner housing and the inlet of the second channel at the shaft.

In this case, where the fluid circulation device serves as the ejector, the shaft can be driven by the electric motor to quickly rotate in one circumferential direction or to alternately rotate (i.e., swing) in two circumferential directions. Therefore, according to a rotating speed of the electric motor, the first channel at the inner housing can be connected to the second channel at the shaft at a required frequency, which thereby provides a pulsed jet at a required frequency. In this case, unreacted hydrogen gas at the stack can be sucked into the mixing chamber via the diversion input path, and thus the unreacted hydrogen gas can be recycled.

The fluid circulation device provided here can be applied into a hydrogen circulation loop of a fuel cell system. Since the fluid circulation device integrates functions of both the proportional valve and the ejector, when the stack is operating at different powers, the fluid circulation device can operate in a proportional valve mode or an ejector mode, which can cover a full power range of the stack in the fuel cell system. Furthermore, since the fluid circulation device provided here has a simple structure, it can be manufactured at a low cost. The fluid circulation device according to the disclosure only needs to drive the shaft to rotate, so it generates a very small amount of additional energy consumption, especially as compared to a hydrogen circulation solution in which a circulation pump is disposed. Moreover, the fluid circulation device according to the embodiment also has an advantage of low operating noise, especially as compared to a hydrogen circulation solution in which a solenoid valve is disposed.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, advantages, and technical effects of exemplary embodiments of the disclosure will be described below with reference to accompanying drawings.

Fig. 1 is a schematic axial cross-sectional view of a fluid circulation device according to an embodiment;

Figure 2 is a schematic cross-sectional view at A-A of Fig. 1 in a state of the fluid circulation device;

Fig. 3 is a schematic cross-sectional view at A-A of Fig. 1 in another state of the fluid circulation device.

DETAILED DESCRIPTION

Fig. 1 schematically shows an axial cross-sectional view of a fluid circulation device according to an embodiment. The fluid circulation device can be disposed in a hydrogen circulation loop of a fuel cell system.

The fluid circulation device is configured to include two input paths, i.e., a jet input path 11 and a diversion input path 10.

The jet input path 11 can be directly or indirectly connected to a hydrogen storage tank in the hydrogen circulation loop via a valve or other components, and thereby new hydrogen gas can be delivered to the jet input path 11. The jet input path 11 has two sections, i.e., a first channel 2 and a second channel 12.

In the embodiment, the fluid circulation device includes a shaft 13, an inner housing 3 and an electric motor 1. In this case, the inner housing 3 has a cylindrical inner cavity, and an axial end of the shaft 13 is centrally disposed in the inner cavity. The other axial end of the shaft 13 can be directly driven by the electric motor 1 so that the shaft 13 can rotate with respect to the inner housing 3.

The first channel 2 of the jet input path 11 is constructed here as a through hole that passes through an outer circumferential surface and an inner circumferential surface of the inner housing 3 in a radial direction. The second channel 12 of the jet input path 11 is constructed within the shaft 13. The second channel 12 includes a first section and a second section that are connected to each other. The first section extends in the radial direction from an outer circumferential surface of the shaft 13 to a center of the shaft 13, and an axial position of the first section is arranged so that when the shaft 13 and the inner housing 3 are at a specific relative position, the first section at the shaft 13 can be connected to the first channel 2 at the inner housing 3. The second section is formed centrally in the shaft 13 in the radial direction and extends from the first section to an axial end side of the shaft 13 in an axial direction.

Fig. 2 and Fig. 3 schematically show cross-sectional views at A-A of Fig. 1 in different states of the fluid circulation device. As described above, the shaft 13 can be driven by the electric motor 1 to rotate with respect to the inner housing 3. Therefore, when the shaft 13 is at different angular positions with respect to the inner housing 3, the first channel 2 and the second channel 12 can be connected, partially connected or disconnected, which thereby achieves different connecting-disconnecting states of the jet input path 11. When the shaft 13 rotates with respect to the inner housing 3 to a relative position as shown in Fig. 2, an inlet of the second channel 12 and an outlet of the first channel 2 are aligned with each other, and then the jet input path 11 is connected. When the shaft 13 rotates with respect to the inner housing 3 to a relative position as shown in Fig. 3, the inlet of the second channel 12 and the outlet of the first channel 2 are offset from each other in a circumferential direction, and then the jet input path 11 is disconnected.

The diversion input path 10 can be directly or indirectly connected to a hydrogen outlet of a stack of the fuel cell system, so that unreacted hydrogen gas can be delivered to the diversion input path 10. To this end, as shown in Fig. 1, the fluid circulation device according to the embodiment further includes an outer housing 8, wherein the outer housing 8 is disposed to surround an axial end of the inner housing 3 away from the electric motor 1 with respect to the first channel 2. Therefore, the diversion input path 10 can be jointly formed by the outer housing 8 and the inner housing 3.

As shown in Fig. 1, the fluid circulation device is also constructed with a nozzle 5 at an outlet of the jet input path 10. In the embodiment, the nozzle 5 is integrally formed at the axial end of the inner housing 3 so that new hydrogen gas from the jet input path 11 can be injected from the nozzle 5 via an injection chamber 4. In this case, the nozzle 5 is arranged coaxially with the cylindrical inner cavity of the inner housing 3.

The fluid circulation device further includes a mixing chamber 6, a diffusion chamber 7 and a mixed fluid output path 9 successively located downstream of the nozzle 5 in a flow direction of the new hydrogen gas, wherein the mixing chamber 6 is also connected to the diversion input path 10. In the embodiment, the outer housing 8 is constructed as a venturi tube, and the mixing chamber 6, the diffusion chamber 7, and the mixed fluid output path 9 are formed in the outer housing 8. The outer housing 8 in this case is disposed coaxially with the inner housing 3. In this case, the outlet of the jet input path 11, the nozzle 5, the mixing chamber 6, and the diffusion chamber 7 are sequentially disposed on a same axis along the flow direction of the fluid.

Thus, according to a control strategy of the electric motor 1, the fluid circulation device can provide two operating modes.

In a case where the stack of the fuel cell system is operated at a medium to high power (for example, 25%or more of a full power) , the fluid circulation device serves as a proportional valve. In this case, the shaft 13 can be driven by the motor 1 to rotate with respect to the inner housing 3, which adjusts an overlap rate of the outlet of the first channel 2 at the inner housing 3 and the inlet of the second channel 12 at the shaft 13, thereby controlling an opening rate of the proportional valve. Therefore, according to requirements of the fuel cell system, new hydrogen gas with a required flow rate can be provided through the jet input path 11, and the new hydrogen gas then flows through the nozzle 5, the mixing chamber 6, the diffusion chamber 7 and the mixed fluid output path 9, and then enters downstream components of the hydrogen circulation loop.

In a case where the stack of the fuel cell system operates at a low power (for example, below 25%of the full power) , the fluid circulation device serves as an ejector. In this case, the shaft 13 can be driven by the electric motor 1 to quickly rotate in one circumferential direction or to alternately rotate (i.e., swing) in two circumferential directions, so that the first channel 2 at the inner housing 3 can be connected to the second channel 12 at the shaft 13 at a required frequency, which thereby provides a pulsed jet at a required frequency. Accordingly, the new hydrogen gas at a high pressure which is input through the jet input path 11 can be injected into the mixing chamber 6 through the nozzle 5 as a main flow. In this case, recycled hydrogen gas at a low pressure will be sucked into the mixing chamber 6 via the diversion input path 10 as a secondary flow. Subsequently, the new hydrogen gas and the recycled hydrogen gas which have been mixed in the mixing chamber 6 can be decelerated and pressurized in the diffusion chamber 7 and output from the mixed fluid output path 9, and then enter the downstream components of the hydrogen circulation loop.

Since the fluid circulation device integrates functions of both the proportional valve and the ejector, when the stack is operating at different powers, the fluid circulation device can operate in a proportional valve mode or an ejector mode, which can cover a full power range of the stack in the fuel cell system. Furthermore, since the fluid circulation device provided here has a simple structure, it can be manufactured at a low cost. The fluid circulation device according to the embodiment only needs to drive the shaft to rotate, so it generates a very small amount of additional energy consumption. Moreover, the fluid circulation device according to the embodiment also has an advantage of low operating noise.

In the description herein, it should be noted that, unless otherwise specified, the terms "axial direction" , "radial direction" and "circumferential direction" are all defined with reference to a rotating axis of the shaft. Furthermore, the terms "first" , "second" , etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance.

Furthermore, the above specific embodiments further describe the purpose, technical solutions and beneficial effects of the disclosure in further detail. It should be understood that the above embodiment is only a specific embodiment of the disclosure and does not limit the protection scope of the disclosure; without departing from the basic characteristics of the disclosure, the disclosure can be embodied in various forms; therefore, the embodiments of the disclosure are intended to be illustrative instead of limiting, because the scope of the disclosure is defined by the claims rather than the description; and all variations falling within the scope defined by the claims or equivalent scopes of the scope defined therein shall be construed as being included in the claims. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the disclosure shall be included in the protection scope of the disclosure.

Reference Sign List

1 electric motor

2 first channel

3 inner housing

4 injection chamber

5 nozzle

6 mixing chamber

7 diffusion chamber

8 outer housing

9 mixed fluid output path

10 diversion input path

11 jet input path

12 second channel

13 shaft

Claims

A fluid circulation device, comprising:

a jet input path (11) and a diversion input path (10) ,

a nozzle (5) constructed at an outlet of the jet input path (11) ,

a mixing chamber (6) located downstream of the nozzle (5) and connected to the diversion input path (10) , and

a diffusion chamber (7) and a mixed fluid output path (9) successively located downstream of the mixing chamber (6) ,

characterized in that,

the jet input path (11) comprises an upstream first channel (2) constructed at an inner housing (3) and a downstream second channel (12) constructed at a shaft (13) ,

wherein the inner housing (3) has a cylindrical inner cavity and the shaft (13) is disposed in the inner cavity, and

wherein the fluid circulation device further comprises an electric motor (1) , which can drive the shaft (13) to rotate with respect to the inner housing (3) , so that the first channel (2) and the second channel (12) are connected, partially connected or disconnected.
The fluid circulation device according to claim 1, wherein the first channel (2) is configured as a through hole that passes through an outer circumferential surface and an inner circumferential surface of the inner housing (3) .
The fluid circulation device according to claim 2, wherein the second channel (12) comprises a first section and a second section connected to each other, wherein the first section at least partially extends in a radial direction and is connected to the first channel (2) , and the second section extends in an axial direction and is connected to the nozzle (5) .
The fluid circulation device according to claim 1, wherein the nozzle (5) is integrally constructed at an axial end of the inner housing (3) .
The fluid circulation device according to claim 4, wherein the fluid circulation device comprises an outer housing (8) , wherein the outer housing (8) is disposed to surround an axial end of the inner housing (3) which is provided with the nozzle (5) to form the diversion input path (10) , and the outer housing (8) forms the mixing chamber (6) , the diffusion chamber (7) and the mixed fluid output path (9) .
The fluid circulation device according to claim 1, wherein the electric motor (1) directly drives the shaft (1) to rotate.
The fluid circulation device according to claim 6, wherein a speed change mechanism is disposed between the electric motor (1) and the shaft (13) .
The fluid circulation device according to claim 7, wherein the electric motor (1) and the shaft (13) are disposed coaxially or disposed parallel to each other.
A fuel cell system, characterized in that the fuel cell system comprises a stack and a fluid circulation device according to any one of claims 1 to 8, wherein

the jet input path (11) of the fluid circulation device can be connected to a hydrogen storage container in the fuel cell system, and the diversion input path (10) of the fluid circulation device can be connected to a hydrogen outlet of the stack of the fuel cell system.
An operating method of a fluid circulation device in a fuel cell system according to claim 9, characterized in that,

when the stack is operated at a medium to high power, the fluid circulation device serves as a proportional valve;

when the stack is operated at a low power, the fluid circulation device serves as an ejector.