Electric pile

Abstract

The utility model provides a galvanic pile, which comprises a galvanic pile body, an anode inlet main pipe, an anode outlet main pipe, a cathode inlet main pipe and a cathode outlet main pipe, the feeding pipeline and the discharging pipeline are arranged on the electric pile body, the feeding pipeline is configured to introduce fuel into an anode inlet header pipe of the electric pile body, and the discharging pipeline is configured to lead out redundant fuel from an anode outlet header pipe of the electric pile body; the discharging pipeline comprises a first part directly connected with the anode outlet main pipe and a second part connected with the first part and used for being connected with a fuel subsystem of the fuel cell system, and an additional fuel cavity is defined in the first part. By arranging the fuel cavity on the discharge pipeline of the galvanic pile, when fuel starvation occurs in the galvanic pile, the fuel can be reversely sucked into the galvanic pile from the fuel cavity, so that on one hand, the influence of fuel starvation is relieved, components in the galvanic pile are protected, on the other hand, the air pressure change in the discharge pipeline is reduced, and the service life of the discharge pipeline is prolonged; and the reliability is improved.

Description

Technical Field

[0001] The utility model relates to the field of fuel cells, in particular to a fuel cell stack. Background Art

[0002] Fuel cell systems that generate electricity by electrochemical reactions between fuel and oxidant are increasingly being used to provide electricity. Proton exchange membrane fuel cell (PEMFC) systems are a widely used fuel cell system that usually uses hydrogen as fuel. During the operation of PEMFC, hydrogen as fuel is supplied to the anode of the PEMFC stack and adsorbed by the catalyst to be ionized into hydrogen ions and electrons. The hydrogen ions are transferred to the cathode via the proton exchange membrane, and the electrons flow to the cathode through the external circuit to form an electric current to the outside.

[0003] Generally, in order to ensure the continuous and stable operation of the fuel cell, it is preferred to pass an excess amount of hydrogen into the fuel cell system (i.e., the amount of hydrogen introduced into the stack per unit time is greater than the amount of hydrogen consumed by the stack per unit time). Therefore, in addition to the feed line for introducing hydrogen, a discharge line for discharging excess hydrogen is also required in the stack.

[0004] However, in some cases (for example, rapid load changes, uneven distribution of reactants, rapid start and stop, etc.), it will still lead to insufficient local hydrogen supply (i.e., local pressure drop). At this time, the reaction inside the battery cannot provide enough hydrogen ions (protons) and electrons to maintain charge balance, which requires water electrolysis and carbon corrosion to supplement protons and electrons, and hydrogen starvation (fuel starvation) occurs. Hydrogen starvation is a common cause of PEMFC performance degradation. Mild hydrogen starvation will lead to uneven distribution of current density, while severe hydrogen starvation will cause voltage to drop or even reverse polarity, accelerating the battery's decay rate. In addition, at the location near the discharge pipeline inside the stack, the density of hydrogen will be significantly lower than that near the feed pipeline, making hydrogen starvation more likely to occur, resulting in a local vacuum near the stack outlet. The vacuum formed here will cause the hydrogen in the discharge pipeline to be sucked back into the stack, causing the air pressure in the discharge pipeline to change dramatically in an instant, reducing the service life of the pipeline.

[0005] A similar problem exists in fuel cells using methanol as fuel.

[0006] Therefore, a design is needed to reduce the risk and severity of fuel starvation in the PEMFC stack. Utility Model Content

[0007] The purpose of the present application is to provide a battery stack to solve at least one problem existing in the prior art.

[0008] According to one aspect of the present application, a stack is provided, which includes: a stack body, in which an anode inlet header and an anode outlet header are arranged; and a feed pipeline and a discharge pipeline arranged on the stack body, the feed pipeline is configured to introduce fuel into the anode inlet header of the stack body, and the discharge pipeline is configured to export the excess fuel from the anode outlet header of the stack body, wherein the discharge pipeline includes a first part directly connected to the anode outlet header and a second part connected to the first part and used to connect to the fuel subsystem of the fuel cell system, and an additional fuel chamber is defined in the first part.

[0009] According to an embodiment of the present application, the first part includes a connecting part interconnected with the fuel chamber, and the connecting part is directly connected to the anode outlet header.

[0010] According to an embodiment of the present application, the fuel chamber is configured to be located between the connecting part and the second part, and in a cross-section perpendicular to the flow direction of the fuel, the fuel chamber has a cross-sectional area larger than that of the second part.

[0011] According to an embodiment of the present application, the fuel chamber has a constant cross-sectional area along the flow direction of the fuel.

[0012] According to an embodiment of the present application, the cross-sectional area of the fuel chamber gradually decreases along the flow direction of the fuel.

[0013] According to an embodiment of the present application, in a cross-section perpendicular to the flow direction of the fuel, the cross-section of the fuel chamber is circular.

[0014] According to an embodiment of the present application, a separate fuel chamber is arranged on the first part, and the fuel chamber is only directly connected to the connecting part.

[0015] According to an embodiment of the present application, the volume of the fuel chamber is at least one fiftieth of the volume of the stack body.

[0016] According to an embodiment of the present application, at least a part of the fuel chamber is made of an elastic material.

[0017] According to an embodiment of the present application, the discharge pipeline and the feed pipeline are arranged on different half parts of the stack body.

[0018] By defining a fuel chamber in the first part of the discharge pipeline of the stack, when fuel starvation occurs, the fuel in the fuel chamber can be sucked back into the stack body, thereby alleviating the severity of fuel starvation, protecting the single fuel cells in the stack body, and at the same time being able to reduce the pressure drop in the discharge pipeline caused by fuel starvation, protecting the discharge pipeline and extending the service life of the stack. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Exemplary embodiments of the present application will be described in detail below with reference to the accompanying drawings. It should be understood that the embodiments described below are only for explaining the present application and not for limiting the scope of the present application. In the accompanying

[0020] In the figures:

[0021] Figure 1 A perspective view of a stack according to an exemplary embodiment of the present application is shown. Detailed implementation manners

[0022] The preferred embodiments of the present application will be described in detail below with reference to examples. In the embodiments of the present application, a stack for a proton exchange membrane fuel cell is taken as an example to describe the present application. However, those skilled in the art should understand that these exemplary embodiments do not mean any limitation to the present application. In addition, the features in the embodiments of the present application can be combined with each other without conflict. In different drawings, the same components are denoted by the same reference numerals, and for the sake of brevity, other components are omitted, but this does not mean that the stack of the present application cannot include other components. It should be understood that the dimensions, proportional relationships of the components in the drawings, and the number of components do not constitute a limitation to the present application.

[0023] It will be understood that although terms such as "first" and "second" may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element, without departing from the scope of the present disclosure.

[0024] The overall system of a proton exchange membrane fuel cell generally includes: a fuel subsystem for providing fuel; an air subsystem for providing air; a thermal management subsystem for controlling the temperature of the battery system, and a proton exchange membrane fuel cell stack for realizing an electrochemical reaction. Among them, the fuel subsystem contains a fuel source for providing fuel. The fuel in the fuel source flows through devices such as a pressure valve and finally flows to the feed pipeline provided on the stack, and then flows through the anode inlet manifold connected to the feed pipeline in the stack to the anode of each cell unit in the stack. In addition, the fuel subsystem further includes a separator to separate the excess hydrogen and impurities (such as reaction water, nitrogen, etc.) flowing out through the anode outlet manifold in the stack and the discharge pipeline provided on the stack and connected to the anode outlet manifold, and redirect the hydrogen back to the feed pipeline. The anode inlet manifold and the anode outlet manifold are respectively connected to the flow fields on the anode side of the cell units in the stack, so as to realize the fuel flowing in from the inlet and flowing out from the outlet.

[0025] Figure 1A perspective view of the stack 100 according to an exemplary embodiment of the present application is shown. For clarity, other components located on the surface of the stack body 110 that are not relevant to the technical solution of the present application have been omitted.

[0026] As Figure 1 shown, the stack 100 according to an exemplary embodiment of the present application includes a stack body 110. Generally, as described above, an anode inlet manifold and an anode outlet manifold (not shown) are included within the stack body 110. A feed line (not shown) and a discharge line 120 are provided on the stack body 110. Among them, the feed line is connected to the anode inlet manifold to direct fuel to the anode side of the fuel cell unit, and the discharge line 120 is connected to the anode outlet manifold to discharge excess fuel and reaction products.

[0027] According to an exemplary embodiment of the present application, the discharge line 120 includes a first portion 121 connected to the anode outlet manifold and a second portion 122 connected to the first portion 121 and configured to be connected to the fuel subsystem. Among them, the first portion 121 includes an additional fuel chamber 121a. The fuel chamber 121a has a volume and is configured to be able to store fuel. In actual use of the fuel cell, because the air pressure should remain constant everywhere in the discharge line 120, compared with the existing discharge line of uniform thickness, the first portion 121 provided with the fuel chamber 121a can retain more fuel in the first portion 121. In this way, when a fuel starvation phenomenon occurs in the stack, compared with the prior art, the stack body 110 according to an exemplary embodiment of the present application can suck more fuel from the first portion 121 into the stack, thereby being able to alleviate the severity of fuel starvation. At the same time, due to the presence of the fuel chamber 121a storing more fuel, the fuel backflow caused by fuel starvation of the same severity will only cause a smaller degree of pressure drop, which thus reduces the instantaneous change in the pressure of the discharge line 120, thereby protecting the discharge line 120 and extending the service life of the discharge line 120.

[0028] It should be noted that the so-called fuel chamber does not mean that fuel is stored in the fuel chamber for consumption, but rather that there is always a certain mass of fuel remaining in this space. Since the fuel chamber is a part of the entire discharge line (that is, fluidly connected to other parts of the discharge line), when fuel flows through the discharge line, some fuel in the fuel chamber will inevitably flow out and into the second portion, while the same mass of fuel will flow into the fuel chamber to ensure that the total amount of fuel in the fuel chamber remains unchanged.

[0029] According to an exemplary embodiment of the present application, the first part 121 includes a connection part 121b connected to the additional fuel chamber 121a described above, wherein the connection part 121b is directly connected to the anode outlet manifold. Generally, the connection part 121b is made of the same material as the second part 122, that is to say, the connection part 121b can be regarded as a part of the discharge pipeline in the prior art. In this embodiment, by providing the connection part 121b, the first part 121 can still be adapted to the anode outlet manifold in the existing fuel cell stack, so that the fuel cell stack body can be produced using the existing technology, reducing the manufacturing cost of the fuel cell stack. However, in another embodiment, the connection part may not be provided, but the fuel chamber is directly connected to the anode outlet manifold. In this case, the anode outlet manifold will be adaptively improved. This structure facilitates the backflow of fuel from the fuel chamber into the fuel cell stack, increases the recovery speed of fuel supply when fuel starvation occurs, and reduces the severity of fuel starvation.

[0030] According to an exemplary embodiment of the present application, the fuel chamber 121a is configured to be located between the connection part 121b and the second part 122, and preferably in a cross-section perpendicular to the fuel flow direction, the cross-sectional area of the fuel chamber 121a is larger than the cross-sectional area of the second part 122. In this way, the length of the fuel chamber (along the fuel flow direction) can be relatively reduced, while further reducing the pressure drop in the first part 121 during backflow, thereby protecting the discharge pipeline 120.

[0031] According to an exemplary embodiment of the present application, the fuel chamber 121a has a uniform cross-sectional area. Providing a uniform cross-sectional area facilitates the manufacture of the discharge pipeline 120, and at the same time makes the fuel chamber 121a more stable and reliable when the internal fuel pressure changes.

[0032] Alternatively, the cross-sectional area of the fuel chamber 121a gradually decreases along the fuel flow direction. That is to say, the fuel chamber 121a is formed in a trapezoidal shape. In such an embodiment, through the gradually decreasing cross-sectional area, a smooth transition between the fuel chamber 121a and the second part 122 is achieved, thereby avoiding a sudden drop in the cross-sectional area at the connection between the fuel chamber 121a and the second part 122 similar to that at the connection between the fuel cell stack body 110 and the connection part 121b or the fuel chamber 121a. This not only extends the service life of the second part 122, but also increases the stability of the system, because a sudden drop in the cross-sectional area will exacerbate the local pressure change during fuel starvation.

[0033] Generally, in a cross-section perpendicular to the flow direction of the fuel, the shape of the cross-section of the outlet pipe 120 can be arbitrary. However, preferably, according to an exemplary embodiment of the present application, the cross-section of the connecting portion 121b is circular. The circular connecting portion 121b is not only suitable for the shapes of the existing fuel cell stack body 110 and the second portion 122, but also reduces the internal stress, making the connecting portion 121b more stable and reliable when the fuel pressure inside it changes.

[0034] In other embodiments, alternatively, the first portion 121 may include a separate volume space provided on the connecting portion 121b (i.e., directly connected only to the connecting portion 121b), and this volume space is used as the fuel chamber 121a. In such an embodiment, the fuel chamber 121a is internally connected to the connecting portion 121b, so that the fuel passing through the connecting portion 121b can be stored in the fuel chamber 121a. Providing a separate fuel chamber 121a can avoid changes to the existing fuel cell system structure, because compared with the case where the fuel chamber 121a is provided between the connecting portion 121b and the second portion 122, the cross-sectional area that the connecting portion 121b should have in the alternative embodiment is relatively smaller (e.g., the same as that of the second portion), and in some cases, it is not feasible to provide a fuel chamber 121a with a large cross-sectional area in situ in the first portion 121.

[0035] In addition, in order to increase the effect of anti-suction, the volume of the fuel chamber 121a is designed to be at least one-fiftieth of the volume of the fuel cell stack body 110. In this way, when a very serious fuel starvation occurs, there will still be enough fuel remaining in the fuel chamber 121a, thereby alleviating the impact caused by fuel starvation and extending the life of the fuel cell stack 100.

[0036] In an exemplary embodiment according to the present application, as shown in the figure, the fuel chamber 121a is made of an inelastic material. However, in other embodiments, at least a part of the fuel chamber 121a is made of an elastic material. For example, in an embodiment where the fuel chamber 121a is provided between the connecting portion 121b and the second portion 122, the fuel chamber 121a includes an annular elastic material, so that it can expand or contract following the change in air pressure when the air pressure changes. In an embodiment where a separate fuel chamber 121a is provided, the fuel chamber 121a can be in the form of an airbag. In this way, when fuel starvation occurs, the fuel in the airbag will be quickly sucked into the fuel cell stack body 110, and the airbag itself will quickly contract without causing damage to the outlet pipe 120.

[0037] When the stack 100 is installed in a fuel cell system, it is preferably arranged such that the outlet pipeline 120 and the inlet pipeline are at different heights to facilitate the flow of fuel. For example, in a fuel cell using hydrogen as fuel, since hydrogen has a low density, preferably the outlet pipeline 120 should be arranged in the upper half of the stack body 110, while the inlet pipeline is arranged in the lower half of the stack body 110. In this arrangement, hydrogen tends to move towards the outlet pipeline, thereby balancing the hydrogen density within the stack body and reducing the possibility of fuel starvation. It should be noted that since the installation direction of the stack can be arbitrary, when the stack is not installed, the above-mentioned upper half and lower half do not mean that the outlet pipeline 120 and the inlet pipeline are arranged in a specific direction, but only aim to indicate that the outlet pipeline 120 and the inlet pipeline are arranged in different halves.

[0038] The above embodiments of the present application provide a stack. According to the technical solution of the present application, by providing a fuel chamber on the outlet pipeline of the stack, when fuel starvation occurs in the stack, fuel can be sucked back into the stack from the fuel chamber, thereby on the one hand alleviating the impact of fuel starvation, protecting the components inside the stack, and on the other hand reducing the pressure change in the outlet pipeline, extending the life of the outlet pipeline and increasing the reliability.

[0039] The present application has been described in detail above in conjunction with specific embodiments. Obviously, the above description and the embodiments shown in the drawings should be understood as exemplary and do not constitute a limitation to the present application. For those skilled in the art, various variations or modifications can be made without departing from the spirit of the present application, and these variations or modifications do not depart from the scope of the present application.

Claims

1. A battery stack (100), comprising: A battery stack body (110), wherein an anode inlet manifold and an anode outlet manifold are arranged in the battery stack body (110); as well as A feed pipeline and a discharge pipeline (120) are arranged on the stack body (110), wherein the feed pipeline is configured to pass the fuel into the anode inlet manifold of the stack body (110), and the discharge pipeline (120) is configured to discharge the excess fuel from the anode outlet manifold of the stack body (110). It is characterized in that the discharge pipeline (120) includes a first part (121) directly connected to the anode outlet main pipe and a second part (122) connected to the first part (121) and used to connect to the fuel subsystem of the fuel cell system, and an additional fuel chamber (121a) is defined in the first part (121).

2. The fuel cell stack (100) according to claim 1, characterized in that: The first part (121) includes a connecting part (121b) interconnected with the fuel chamber (121a), and the connecting part (121b) is directly connected to the anode outlet main pipe.

3. The fuel cell stack (100) according to claim 2, characterized in that: The fuel cavity (121a) is configured to be located between the connecting portion (121b) and the second portion (122), and in a cross section perpendicular to a flow direction of the fuel, the fuel cavity (121a) has a cross-sectional area greater than that of the second portion (122).

4. The fuel cell stack (100) according to claim 3, characterized in that: The fuel cavity (121a) has a constant cross-sectional area along the flow direction of the fuel.

5. The fuel cell stack (100) according to claim 3, characterized in that: The cross-sectional area of ​​the fuel cavity (121a) gradually decreases along the flow direction of the fuel.

6. The fuel cell stack (100) according to claim 4 or 5, characterized in that: In a cross section perpendicular to a flow direction of the fuel, the cross section of the fuel chamber (121a) is circular.

7. The fuel cell stack (100) according to claim 2, characterized in that: The first part (121) is provided with a separate fuel chamber (121a), and the fuel chamber (121a) is directly connected only to the connecting part (121b).

8. The fuel cell stack (100) according to claim 3 or 7, characterized in that: The volume of the fuel chamber (121a) is at least one fiftieth of the volume of the fuel cell stack body (110).

9. The fuel cell stack (100) according to claim 8, characterized in that: At least a portion of the fuel chamber (121a) is made of elastic material.

10. The fuel cell stack (100) according to claim 9, characterized in that: The discharge pipeline (120) and the feed pipeline are arranged on different halves of the fuel cell stack body (110).

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