A secondary water separation device for multi-stack fuel cells and multi-stack fuel cells

Abstract

The present invention provides a secondary water separation device for multi-stack fuel cells and a multi-stack fuel cell, which belongs to the field of fuel cell technology and solves the problem of incomplete water separation in the prior art leading to a decrease in fuel cell performance. The secondary water separation device includes a first gas-liquid separator in the shape of a liquid storage tank, a second gas-liquid separator in the shape of a tube, and a liquid storage cavity. Among them, the top of the first gas-liquid separator is provided with a gas outlet, the middle is provided with a port for connecting to the hydrogen outlet of each fuel cell, and the bottom is provided with a liquid storage cavity. The bottom of the liquid storage cavity is provided with a drain port, and the side wall is provided with a port for connecting to the second gas-liquid separator. The second gas-liquid separator adopts a serpentine tubular structure, with a low-level water storage site and a high-level drain site in the middle, one end is connected to the hydrogen inlet of each fuel cell, and the other end is connected to the port on the above-mentioned side wall of the liquid storage cavity. The device can be set in the bottom inlet manifold to solve the problem that the bottom fuel cell is more prone to water accumulation and improve the consistency of multiple stacks.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular to a secondary water separation device for multi-stack fuel cells and the multi-stack fuel cells. Background Art

[0002] Fuel cells are increasingly being used in high-power applications such as large vehicles and commercial vehicles, thanks to their advantages such as long driving range, fast refueling speed, and high load capacity. Achieving high power output from a fuel cell system can be achieved through the use of a dual-stack approach, that is, by connecting two fuel cell stacks in parallel. To ensure consistent performance of the dual stacks, operating parameters such as inlet pressure and temperature need to be controlled, so the inlet manifold is crucial for flow distribution. However, due to the presence of liquid water in the inlet mixture, gravity causes a large amount of liquid water to accumulate in the bottom inlet manifold. Once this water enters the stack, the dual stacks operate differently, resulting in decreased performance in the bottom stack.

[0003] Fuel cell systems often utilize a hydrogen recirculation system. This system uses a circulating pump or ejector to recirculate unconsumed hydrogen from the fuel cell's exiting mixture (containing hydrogen, water vapor, nitrogen, liquid water, and other gases) back into the stack, improving hydrogen utilization. Due to the significant density difference between liquid water and gas, entering the stack can potentially block the fuel cell reaction channels, causing the stack to malfunction. Therefore, a gas-liquid separator is typically installed at the hydrogen outlet to separate and discharge liquid water from the gas-liquid mixture, preventing it from recirculating into the stack. However, smaller droplets cannot be completely separated by the gas-liquid separator. Furthermore, after exiting the gas-liquid separator and entering the downstream pipeline, water vapor in the mixture may condense due to heat dissipation to the environment and pressure changes. Consequently, a small amount of liquid water may remain in the incoming gas, degrading stack performance. Summary of the Invention

[0004] In view of the above analysis, the embodiments of the present invention aim to provide a secondary water separation device for multi-stack fuel cells and a multi-stack fuel cell, so as to solve the problem of incomplete water separation in the prior art leading to decreased fuel cell stack performance.

[0005] On the one hand, an embodiment of the present invention provides a secondary water separation device for a multi-stack fuel cell, comprising a first gas-liquid separator (8) in the shape of a liquid storage tank, a second gas-liquid separator (10) in the shape of a tube, and a liquid storage chamber; wherein,

[0006] The first gas-liquid separator (8) is provided with a gas outlet at the top, a port for connecting to each hydrogen outlet of the fuel cell stack at the middle, and a liquid storage chamber at the bottom;

[0007] The bottom of the liquid storage chamber is provided with a drain port, and the side wall is provided with a port for connecting to the second gas-liquid separator (10);

[0008] The second gas-liquid separator (10) adopts a serpentine tubular structure, with a low-level water storage site (10a) and a high-level drainage site (10b) in the middle, one end of which is connected to the hydrogen inlet of each fuel cell stack, and the other end of which is connected to the port on the side wall of the liquid storage chamber.

[0009] The beneficial effects of the above technical solution are as follows: a secondary water separation solution on the hydrogen side suitable for multi-stack fuel cells is proposed, and a secondary water separation device can be set in the bottom inlet manifold to solve the problem of water accumulation in the bottom fuel cell stack and improve the consistency of multiple stacks.

[0010] Based on the further improvement of the above device, the second gas-liquid separator (10) has a low-level water storage point (10a) and a high-level drainage point (10b); and,

[0011] The low-level water storage point (10a) is provided on a side close to the hydrogen inlet of the fuel cell stack to accommodate liquid water accumulated at the bottom of the second gas-liquid separator (10);

[0012] The hydrogen pressure inside the second gas-liquid separator (10) is greater than or equal to the hydraulic pressure of the liquid water stored between the low-level water storage point (10a) and the high-level drainage point (10b).

[0013] The beneficial effects of the above further solution are as follows: the airflow inside the second gas-liquid separator (10) needs to overcome the hydraulic pressure of the liquid water stored between the low-level water storage point (10a) and the high-level drainage point (10b) before it can be further discharged to the drain outlet through the pipeline.

[0014] Furthermore, the secondary water distribution device also includes a drainage pipeline; and,

[0015] The drainage pipeline is used to connect the low-level water storage point (10a) of the second gas-liquid separator (10) with the liquid storage chamber, and has an inclination such that all liquid water accumulated at the low-level water storage point (10a) flows into the liquid storage chamber.

[0016] The beneficial effects of the above further solution are as follows: preventing the accumulation of liquid water inside the second gas-liquid separator (10).

[0017] Furthermore, the secondary water distribution device also includes an inlet manifold and an outlet manifold; wherein,

[0018] For a dual-stack fuel cell placed up and down, the hydrogen outlet of the top stack (6) and the hydrogen outlet of the bottom stack (7) are combined into one channel through their respective stack outlet manifolds and then connected to the corresponding port in the middle of the first gas-liquid separator (8);

[0019] The port in the middle of the second gas-liquid separator (10) is dispersed into two paths through the stack outlet manifold and respectively connected to the corresponding hydrogen inlet of the top fuel cell stack (6) and the hydrogen inlet of the bottom fuel cell stack (7).

[0020] The beneficial effects of the above further solution are as follows: after adding the inlet manifold and the outlet manifold, the integration of the secondary water separation device is made higher.

[0021] Furthermore, the secondary water distribution device further includes a drain valve (9); wherein,

[0022] The drain valve (9) is arranged at the bottom of the liquid storage chamber and is connected to the drain port of the liquid storage chamber.

[0023] The beneficial effects of the above further solution are as follows: after adding the drain valve, the discharge of liquid water in the liquid storage chamber can be accurately controlled.

[0024] Furthermore, the secondary water distribution device also includes a controller; the output end of which is connected to the control end of the drain valve (9), and,

[0025] The controller is used to control the opening frequency of the drain valve (9) and the opening time of each cycle, so that the liquid water stored in the liquid storage chamber is discharged from the drain valve (9) at a set rate.

[0026] The beneficial effects of the above further solution are as follows: after adding a controller, the opening of the drain valve can be automatically controlled according to the liquid level.

[0027] Furthermore, the drainage pipeline is arranged near the high-temperature water outlet of the multiple fuel cell stacks.

[0028] The beneficial effects of the above further solution are as follows: freezing of the drainage pipe can be avoided in a low temperature environment.

[0029] Furthermore, a swirl blade or baffle is provided in the port in the middle of the first gas-liquid separator (8);

[0030] The swirl blades are configured to generate a swirl around the center when the gaseous mixture at the hydrogen outlet of the fuel cell stack flows through the channel of the first gas-liquid separator (8), and liquid water droplets in the gaseous mixture are affected by the swirl and flow along the inner wall of the first gas-liquid separator (8) toward the bottom;

[0031] The baffle is configured to have an inclination angle, so that gas-liquid separation can be achieved when the gaseous mixture at the hydrogen outlet of the fuel cell stack flows through the channel with the baffle.

[0032] The beneficial effects of the above further solution are as follows: gas-liquid separation can be achieved through the swirl blades or baffles.

[0033] On the other hand, an embodiment of the present invention provides a multi-stack fuel cell, comprising the above-mentioned secondary water separation device, as well as multiple fuel cell stacks, hydrogen injection equipment (3), and ejectors (4); wherein,

[0034] The power supply output terminals of each battery stack are connected in parallel;

[0035] The first input end of the ejector (4) is connected to the output end of the hydrogen injection device (3), the second input end is connected to the gas outlet at the top of the first gas-liquid separator (8), and the output end is connected to the hydrogen inlet of each fuel cell stack.

[0036] The beneficial effects of adopting the above solution are: solving the problem of water accumulation at the bottom of the battery stack and improving the consistency of multiple stacks.

[0037] Based on the further improvement of the above fuel cell, the multi-stack fuel cell further includes a hydrogen bottle (1) and a pressure reducing valve (2) connected in sequence; and,

[0038] The output end of the pressure reducing valve (2) is connected to the input end of the hydrogen injection device (3).

[0039] The beneficial effect of adopting the above-mentioned further improved solution is that, after adding the hydrogen bottle (1) and the pressure reducing valve (2), the control of hydrogen entering the stack of multiple fuel cells is made more precise.

[0040] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the disclosure, nor is it intended to limit the scope of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The above and other objects, features and advantages of the present disclosure will become more apparent through a more detailed description of exemplary embodiments of the present disclosure with reference to the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present disclosure.

[0042] Figure 1 A schematic diagram of the composition of a secondary water separation device for multiple fuel cell stacks according to Example 1 is shown;

[0043] Figure 2 A schematic diagram of the composition of multiple fuel cell stacks in Example 3 is shown.

[0044] Reference numerals:

[0045] 1- Hydrogen bottle; 2- Pressure reducing valve; 3- Hydrogen spray equipment; 4- Ejector; 5- Secondary water separation device;

[0046] 6- top fuel cell stack; 6a- top fuel cell stack hydrogen inlet; 6b- top fuel cell stack hydrogen outlet;

[0047] 7- bottom fuel cell stack; 7a- bottom fuel cell stack hydrogen inlet; 7b- bottom fuel cell stack hydrogen outlet;

[0048] 8- First gas-liquid separator; 8a- Liquid storage chamber; 8b- Drain outlet; 8c- Gas outlet;

[0049] 9- Drain valve; 10- Second gas-liquid separator; 10a- Low-level water storage point; 10b- High-level drainage point. DETAILED DESCRIPTION

[0050] Embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to make the present disclosure more thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art.

[0051] As used herein, the term "including" and its variations represent open inclusion, i.e., "including but not limited to." Unless otherwise stated, the term "or" means "and / or." The term "based on" means "based at least in part on." The terms "an example embodiment" and "an embodiment" mean "at least one example embodiment." The term "another embodiment" means "at least one additional embodiment." The terms "first," "second," etc. may refer to different or the same objects. Other explicit and implicit definitions may also be included below.

[0052] Example 1

[0053] One embodiment of the present invention discloses a secondary water separation device for multiple fuel cell stacks, such as Figure 1 As shown, it includes a first gas-liquid separator 8 in the shape of a liquid storage tank, a second gas-liquid separator 10 in the shape of a tube, and a liquid storage chamber.

[0054] The first gas-liquid separator 8 has a gas outlet at the top, a port in the middle for connecting to each fuel cell stack's hydrogen outlet, and a liquid storage chamber at the bottom. The liquid storage chamber has a drain outlet at the bottom and a port on the sidewall for connecting to the second gas-liquid separator 10. The second gas-liquid separator 10 has a serpentine tubular structure with a low-level water storage point 10a and a high-level drain point 10b in the middle. One end is connected to each fuel cell stack's hydrogen inlet, and the other end is connected to the port on the liquid storage chamber's sidewall.

[0055] It should be noted that the first gas-liquid separator 8 in the shape of a liquid storage tank and the liquid storage chamber can be integrated. Figure 2 As shown, it can also be set up separately as two connected independent devices, which can be understood by those skilled in the art.

[0056] Compared with the existing technology, this embodiment proposes a secondary water separation solution on the hydrogen side suitable for multi-stack fuel cells. A secondary water separation device can be set in the bottom inlet manifold to solve the problem of water accumulation in the bottom fuel cell stack 7 and improve the consistency of multiple stacks.

[0057] Example 2

[0058] Based on the improvement of Example 1, the second gas-liquid separator 10 has a low-level water storage point 10a and a high-level drainage point 10b. The low-level water storage point 10a is located on the side close to the hydrogen inlet of the fuel cell stack to accommodate liquid water accumulation at the bottom of the second gas-liquid separator 10.

[0059] Preferably, the hydrogen pressure inside the second gas-liquid separator 10 is greater than or equal to the hydraulic pressure of the liquid water stored between the low-level water storage point 10a and the high-level drainage point 10b.

[0060] Preferably, the secondary water separation device further includes a drainage pipeline. The drainage pipeline is used to connect the low-level water storage point 10a of the second gas-liquid separator 10 with the liquid storage chamber and has an inclination so that all liquid water accumulated at the low-level water storage point 10a flows into the liquid storage chamber.

[0061] The drainage pipeline is provided with a shutoff valve to ensure that as little gas as possible is bypassed. Preferably, the secondary water separation device further includes an inlet manifold and an outlet manifold.

[0062] Among them, for the dual-stack fuel cells placed up and down, the hydrogen outlet of the top stack 6 and the hydrogen outlet of the bottom stack 7 are merged into one through their respective stack manifolds and then connected to the corresponding port in the middle of the first gas-liquid separator 8.

[0063] The middle port of the second gas-liquid separator 10 is dispersed into two paths through the stack outlet manifold and respectively connected to the corresponding hydrogen inlet of the top fuel cell stack 6 and the hydrogen inlet of the bottom fuel cell stack 7.

[0064] Preferably, the secondary water distribution device further comprises a drain valve 9. The drain valve 9 is arranged at the bottom of the liquid storage chamber and connected to the drain port of the liquid storage chamber.

[0065] Preferably, the secondary water distribution device further includes a controller, an output end of which is connected to the control end of the drain valve 9 .

[0066] The controller is used to control the opening frequency and opening time of the drain valve 9 in each cycle, so that the liquid water stored in the liquid storage chamber is discharged from the drain valve 9 at a set rate. Specifically, a liquid level sensor can be set in the liquid storage chamber to control the opening or closing of the valve of the drain pipe by monitoring the internal liquid level.

[0067] Preferably, the drainage pipeline is arranged near the high-temperature water outlet of the multiple fuel cell stacks.

[0068] Preferably, a swirl blade or baffle is provided in the middle port of the first gas-liquid separator 8 .

[0069] The swirl blades are configured to generate a swirl around the center when the gas mixture flows through the channel of the first gas-liquid separator 8. Liquid water droplets in the gas mixture are affected by the swirl and flow along the inner wall of the first gas-liquid separator 8 to the bottom.

[0070] The baffle is configured to have an inclined angle, so that gas-liquid separation can be achieved when the gaseous mixture at the hydrogen outlet of the fuel cell stack flows through the channel with the baffle.

[0071] Compared with Example 1, the secondary water separation device provided in this embodiment has a higher degree of integration, a better gas-liquid separation effect, and can prevent the drainage pipeline from freezing.

[0072] Example 3

[0073] Another embodiment of the present invention provides a multi-stack fuel cell comprising the secondary water separation device of embodiment 1 or 2, further comprising a plurality of fuel cells, a hydrogen injection device 3, and an ejector 4, such as Figure 2 shown.

[0074] The power output terminals of each stack are connected in parallel. The first input terminal of the ejector 4 is connected to the output terminal of the hydrogen injection device 3, the second input terminal is connected to the gas outlet at the top of the first gas-liquid separator 8, and the output terminal is connected to the hydrogen inlet of each stack.

[0075] Preferably, the multi-stack fuel cell further comprises a hydrogen bottle 1 and a pressure reducing valve 2 connected in sequence. In addition, the output end of the pressure reducing valve 2 is connected to the input end of the hydrogen injection device 3.

[0076] During implementation, take two fuel cell stacks as an example, Figure 2 As shown, the gas-liquid mixture (including unconsumed hydrogen, water vapor, nitrogen, and liquid water, etc.) exiting the hydrogen side of the top stack 6 and the bottom stack 7 flows through the stack outlets 6b and 7b, merges through the manifold, and then enters the first gas-liquid separator 8. Gas-liquid separation is completed in the first gas-liquid separator 8, and the separated liquid water is collected in the liquid storage chamber 8a at the bottom of the first gas-liquid separator 8. A drain port 8b is provided at the bottom of the liquid storage chamber, which is connected to a drain valve 9. When the drain valve 9 is opened, the stored liquid water is discharged. The separated mixed gas and a small amount of small-sized droplets that have not been separated flow out from the gas outlet 8c, enter the ejector, and mix with the fresh hydrogen from the hydrogen bottle 1.

[0077] The gas-liquid mixture of fresh hydrogen and reflux hydrogen is distributed through a manifold and enters the top stack 6 and bottom stack 7, respectively. To ensure consistent performance between the two stacks, operating parameters such as inlet pressure and temperature must be kept consistent. A secondary water separation device 5 is located at the very bottom of the inlet manifold. Due to gravity, liquid water accumulates at the bottom of the first gas-liquid separator 8. The drainage pipeline should be as close as possible to the high-temperature water outlet to prevent freezing in low-temperature environments.

[0078] Due to gravity, the stored liquid water first accumulates at the lower reservoir point 10a of the drainage pipeline. As the amount of liquid water increases, the liquid level gradually rises until it reaches the upper drain point 10b of the pipeline. The airflow within the manifold must overcome the hydraulic pressure of the liquid water stored between the lower reservoir point 10a and the upper drain point 10b. The presence of the second gas-liquid separator 10 prevents the airflow from bypassing the drainage pipeline.

[0079] While various embodiments of the present disclosure have been described above, the foregoing description is intended to be illustrative, non-exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is selected to best explain the principles of the embodiments, their practical applications, or improvements over the prior art, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A secondary water separation device for multiple fuel cell stacks, characterized in that: It comprises a first gas-liquid separator (8) in the shape of a liquid storage tank, a second gas-liquid separator (10) in the shape of a tube, and a liquid storage cavity; wherein, The first gas-liquid separator (8) is provided with a gas outlet at the top, a port for connecting to each hydrogen outlet of the fuel cell stack at the middle, and a liquid storage chamber at the bottom; The bottom of the liquid storage chamber is provided with a drain port, and the side wall is provided with a port for connecting to the second gas-liquid separator (10); The second gas-liquid separator (10) adopts a serpentine tubular structure, with a low-level water storage site (10a) and a high-level drainage site (10b) in the middle, one end of which is connected to the hydrogen inlet of each fuel cell stack, and the other end of which is connected to the port on the side wall of the liquid storage chamber; The second gas-liquid separator (10) has a low-level water storage point (10a) and a high-level drainage point (10b); and, The low-level water storage point (10a) is provided on a side close to the hydrogen inlet of the fuel cell stack to accommodate liquid water accumulated at the bottom of the second gas-liquid separator (10); The hydrogen pressure inside the second gas-liquid separator (10) is greater than or equal to the hydraulic pressure of the liquid water stored between the low-level water storage point (10a) and the high-level drainage point (10b); Also includes drainage piping; and, The drainage pipeline is used to connect the low-level water storage point (10a) of the second gas-liquid separator (10) with the liquid storage cavity, and has an inclination so that all the liquid water accumulated at the low-level water storage point (10a) flows into the liquid storage cavity; It also includes an inlet manifold and an outlet manifold; wherein, For a dual-stack fuel cell placed up and down, the hydrogen outlet of the top stack (6) and the hydrogen outlet of the bottom stack (7) are combined into one channel through their respective stack outlet manifolds and then connected to the corresponding port in the middle of the first gas-liquid separator (8); The port in the middle of the second gas-liquid separator (10) is dispersed into two paths through the stack outlet manifold and respectively connected to the corresponding hydrogen inlet of the top fuel cell stack (6) and the hydrogen inlet of the bottom fuel cell stack (7); Also includes a drain valve (9); wherein, The drain valve (9) is arranged at the bottom of the liquid storage chamber and connected to the drain port of the liquid storage chamber; a controller is also included; the output end of the controller is connected to the control end of the drain valve (9), and, The controller is used to control the opening frequency of the drain valve (9) and the opening time of each cycle, so that the liquid water stored in the liquid storage chamber is discharged from the drain valve (9) at a set rate; The drainage pipeline is arranged near the high-temperature water outlet of the multiple fuel cell stacks; A swirl blade or baffle is provided in the port in the middle of the first gas-liquid separator (8); The swirl blades are configured to generate a swirl around the center when the gaseous mixture at the hydrogen outlet of the fuel cell stack flows through the channel of the first gas-liquid separator (8), and liquid water droplets in the gaseous mixture are affected by the swirl and flow along the inner wall of the first gas-liquid separator (8) toward the bottom; The baffle is configured to have an inclined angle, so that gas-liquid separation can be achieved when the gaseous mixture at the hydrogen outlet of the fuel cell stack flows through the channel with the baffle.

2. A multi-stack fuel cell comprising the secondary water separation device according to claim 1, characterized in that: It also includes multiple fuel cells, hydrogen injection equipment (3), and ejectors (4); wherein, The power supply output terminals of each battery stack are connected in parallel; The first input end of the ejector (4) is connected to the output end of the hydrogen injection device (3), the second input end is connected to the gas outlet at the top of the first gas-liquid separator (8), and the output end is connected to the hydrogen inlet of each fuel cell stack.

3. The multi-stack fuel cell according to claim 2, characterized in that: It also includes a hydrogen bottle (1) and a pressure reducing valve (2) connected in sequence; and The output end of the pressure reducing valve (2) is connected to the input end of the hydrogen injection device (3).

Images