A fuel cell stack high stability calculation method and a fuel cell stack

Abstract

The application discloses a fuel cell stack high stability calculation method and a fuel cell, and relates to the technical field of fuel cell stacks. The fuel cell stack high stability calculation method comprises the following steps: determining the actual number of single cells and the actual cross-sectional area of a cell stack core; determining the critical packaging load value of the cell stack according to the actual number of single cells, the actual cross-sectional area of the cell stack core and a single cell number-cell stack core cross-sectional area-cell stack packaging load value relationship diagram; determining the actual height-width ratio of the cell stack core according to the critical packaging load value of the cell stack, the actual number of single cells and a single cell number-cell stack core height-width ratio-cell stack packaging load value relationship diagram; and determining the length, width and height of the cell stack core according to the actual cross-sectional area of the cell stack core and the actual height-width ratio of the cell stack core. The number of single cells, the cross-sectional area of the cell stack core and the height-width ratio of the cell stack core can be matched and designed to ensure the stability of the cell stack.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and in particular to a method for calculating the high stability of a fuel cell stack and a fuel cell stack. Background Technology

[0002] To meet the commercial application requirements of fuel cells, the power demand of fuel cell stacks is increasing. Fuel cell stacks typically consist of dozens to hundreds of individual cells. The simplest and most effective way to increase the power of a fuel cell stack is to increase the number of individual cells. However, as the number of individual cells increases, the height of the stack also increases, while the cross-sectional area of ​​the stack core remains constant. This leads to the stack core becoming increasingly elongated and slender. The length, width, and height of the stack core affect the stability of the stack; an elongated stack core results in poor stability. Currently, there is no method to match the number of individual cells, the cross-sectional area of ​​the stack core, and the aspect ratio of the stack core to ensure the stability of a stack with a large cross-sectional area and a high number of individual cells. Summary of the Invention

[0003] The purpose of this invention is to provide a high stability calculation method for fuel cell stacks and a fuel cell stack, in order to solve the problem that there is currently no method that can match the number of individual cells, the cross-sectional area of ​​the fuel cell stack core, and the aspect ratio of the fuel cell stack core to ensure the stability of fuel cell stacks with large cross-sectional areas and a large number of individual cells.

[0004] To achieve this objective, the present invention adopts the following technical solution:

[0005] A method for calculating the high stability of a fuel cell stack includes:

[0006] Determine the actual number of cells in a single cell and the actual cross-sectional area of ​​the battery stack core;

[0007] Based on the actual number of individual cells, the actual cross-sectional area of ​​the battery stack core, and the relationship between the number of individual cells, the cross-sectional area of ​​the battery stack core, and the battery stack encapsulation load value, the critical encapsulation load value of the battery stack is determined.

[0008] The actual aspect ratio of the battery stack core is determined based on the critical encapsulation load value of the battery stack, the actual number of individual cells, and the relationship between the number of individual cells, the aspect ratio of the battery stack core, and the encapsulation load value of the battery stack.

[0009] The length, width, and height of the battery stack core are determined based on the actual cross-sectional area and the actual aspect ratio of the battery stack core.

[0010] As a preferred approach to the above-mentioned high stability calculation method for fuel cell stacks, based on the empirical aspect ratio and formula of the fuel cell stack: The relationship between the number of single battery cells, the cross-sectional area of ​​the battery stack core, and the battery stack packaging load value is obtained.

[0011] Where P is the critical encapsulation load value of the battery stack; M and Q are both constants; μ is the length coefficient; N is the number of cells per cell; b is the width of the battery stack core; L is the height of the battery stack core; and A is the cross-sectional area of ​​the battery stack core.

[0012] As a preferred embodiment of the above-mentioned calculation method for high stability of fuel cell stacks, based on the empirical cross-sectional area and formula of the fuel cell stack core: The relationship between the number of single cells, the aspect ratio of the battery stack core, and the battery stack packaging load value is obtained.

[0013] Where P is the critical encapsulation load value of the battery stack; M and Q are both constants; μ is the length coefficient; b is the width of the battery stack core; L is the height of the battery stack core; and A is the cross-sectional area of ​​the battery stack core.

[0014] As a preferred embodiment of the above-mentioned high stability calculation method for fuel cell stacks, the actual encapsulation load value of the fuel cell stack is less than the critical encapsulation load value of the fuel cell stack.

[0015] As a preferred embodiment of the above-mentioned high stability calculation method for fuel cell stacks, the number of individual cells multiplied by the thickness of the individual cells equals the height of the fuel cell stack core.

[0016] As a preferred embodiment of the above-mentioned high stability calculation method for fuel cell stacks, the critical encapsulation load value of the stack is inversely proportional to the square of the actual aspect ratio of the stack core, the critical encapsulation load value of the stack is inversely proportional to the actual number of cells in a single cell, and the critical encapsulation load value of the stack is directly proportional to the actual cross-sectional area of ​​the stack core.

[0017] A fuel cell stack, employing the aforementioned high stability calculation method for fuel cell stacks, wherein the fuel cell stack includes a stack core, and the stack core comprises N single cells connected in series, where 200≤N≤500.

[0018] As a preferred embodiment of the aforementioned fuel cell stack, the cross-sectional area of ​​the stack core is A, 0.02m². 2 ≤A≤0.168m 2 .

[0019] As a preferred embodiment of the aforementioned fuel cell stack, the aspect ratio of the stack core is L / b, where 4.0 ≤ L / b ≤ 7.5.

[0020] As a preferred embodiment of the aforementioned fuel cell stack, the critical encapsulation load value of the fuel cell stack is 20kN-50kN.

[0021] The beneficial effects of this invention are:

[0022] This invention provides a method for calculating the high stability of a fuel cell stack and a fuel cell. In this method, after determining the actual number of individual cells and the actual cross-sectional area of ​​the stack core, the critical encapsulation load value of the stack is determined based on a relationship diagram of the number of individual cells, the cross-sectional area of ​​the stack core, and the stack encapsulation load value. After knowing the actual number of individual cells and the critical encapsulation load value, the actual aspect ratio of the stack core is determined based on a relationship diagram of the number of individual cells, the aspect ratio of the stack core, and the stack encapsulation load value. Finally, the length, width, and height of the stack core are determined based on the actual cross-sectional area and the actual aspect ratio of the stack core to ensure the stability of the stack. This method for calculating the high stability of a fuel cell stack ensures the stability of stacks with large cross-sectional areas and a high number of individual cells by matching the number of individual cells, the cross-sectional area of ​​the stack core, and the aspect ratio of the stack core. Attached Figure Description

[0023] Figure 1 This is a graph showing the relationship between the number of single cells, the cross-sectional area of ​​the fuel cell stack core, and the fuel cell stack encapsulation load value in the high stability calculation method for fuel cell stacks provided in a specific embodiment of the present invention.

[0024] Figure 2 This is a graph showing the relationship between the number of single cells, the aspect ratio of the fuel cell stack core, and the fuel cell stack packaging load value in the high stability calculation method for fuel cell stacks provided in a specific embodiment of the present invention. Detailed Implementation

[0025] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0026] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0027] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0028] In the description of this embodiment, the terms "upper," "lower," "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0029] This invention provides a method for calculating the high stability of a fuel cell stack. Figure 1 This is a graph showing the relationship between the number of individual cells, the cross-sectional area of ​​the battery stack core, and the battery stack encapsulation load value. Figure 2This diagram illustrates the relationship between the number of individual cells, the aspect ratio of the fuel cell stack core, and the fuel cell stack encapsulation load value. The high stability calculation method for this fuel cell stack includes: determining the actual number of individual cells and the actual cross-sectional area of ​​the fuel cell stack core; determining the critical encapsulation load value of the fuel cell stack based on the relationship between the actual number of individual cells, the actual cross-sectional area of ​​the fuel cell stack core, and the encapsulation load value; determining the actual aspect ratio of the fuel cell stack core based on the critical encapsulation load value, the actual number of individual cells, and the relationship between the actual number of individual cells, the aspect ratio of the fuel cell stack core, and the encapsulation load value; and determining the length, width, and height of the fuel cell stack core based on the actual cross-sectional area and the actual aspect ratio of the fuel cell stack core. In this high-stability calculation method for fuel cell stacks, after determining the actual number of individual cells and the actual cross-sectional area of ​​the stack core, the critical encapsulation load value of the stack is determined based on the relationship diagram of the number of individual cells, the cross-sectional area of ​​the stack core, and the stack encapsulation load value. After knowing the actual number of individual cells and the critical encapsulation load value, the actual aspect ratio of the stack core is determined based on the relationship diagram of the number of individual cells, the aspect ratio of the stack core, and the stack encapsulation load value. Finally, based on the actual cross-sectional area and the actual aspect ratio of the stack core, the length, width, and height of the stack core are determined to ensure the stability of the stack. This high-stability calculation method for fuel cell stacks ensures the stability of stacks with large cross-sectional areas and a high number of individual cells by matching the number of individual cells, the cross-sectional area of ​​the stack core, and the aspect ratio of the stack core.

[0030] It is understandable that a battery stack core consists of multiple individual cells connected in series. The cross-sectional area of ​​an individual cell is equal to the cross-sectional area of ​​the battery stack core. The thickness of an individual cell multiplied by the number of individual cells equals the height of the battery stack core. The length of the battery stack core multiplied by the width of the battery stack core equals the cross-sectional area of ​​the battery stack core.

[0031] According to Euler's formula, the critical encapsulation load value of the battery stack is:

[0032]

[0033] In the formula: P is the critical encapsulation load value of the battery stack; E(N) is the elastic modulus of the battery stack core, and the battery stack core with different numbers of single cells corresponds to different elastic moduli; I is the moment of inertia of the cross-sectional area of ​​the battery stack core; L is the height of the battery stack core, which is proportional to the number of single cells; μ is the length coefficient, which is a constant related to the constraint method at both ends of the battery stack core.

[0034] Taking a battery stack core with a rectangular cross-section as an example, we have:

[0035]

[0036] A=b·h

[0037] In the formula: h is the length of the battery stack core, b is the width of the battery stack core, and b≤h.

[0038] It is understandable that the corresponding moment of inertia formula is used for battery stack cores with other cross-sectional shapes.

[0039] The battery stack core consists of N individual cells connected in series. After compression, the thickness d of each individual cell is the same, therefore:

[0040]

[0041] For each type of battery stack, the optimal encapsulation process must first be determined. Once determined, each battery stack is encapsulated under this process to achieve the same encapsulation force, so F is a constant. Furthermore, because the forces are balanced in the direction perpendicular to the individual cell surface, the encapsulation force on each individual cell is also F. During normal operation of the battery stack, each individual cell operates in the elastic phase. Due to the uniformity of individual cells, their elastic modulus is always E, therefore:

[0042]

[0043] In the formula: r i is a constant; F is the encapsulation force on a single cell, which is a constant related to the encapsulation process;

[0044] Δx i = The deformation of the i-th single cell.

[0045] The deformation of the i-th single cell can be obtained:

[0046]

[0047] For the battery stack core, the elastic modulus of the battery stack core is E(N), and the overall deformation of the battery stack core is... Therefore:

[0048]

[0049] In the formula: r is a constant.

[0050] We can obtain:

[0051]

[0052] Due to F, r, E, and r i Since all are constants, the above equation can be simplified to:

[0053]

[0054] In the formula: M and Q are both constants.

[0055] Therefore, the critical encapsulation load of the battery stack core is:

[0056]

[0057] Substituting L=d·N, we get:

[0058]

[0059] According to the formula It can be seen that the critical encapsulation load value of the battery stack is inversely proportional to the square of the actual height-to-width ratio of the battery stack core, the critical encapsulation load value of the battery stack is inversely proportional to the actual number of cells in a single cell, and the critical encapsulation load value of the battery stack is directly proportional to the actual cross-sectional area of ​​the battery stack core.

[0060] Optionally, such as Figure 1 and Figure 2 As shown, based on the empirical aspect ratio and formula of the battery stack: The relationship between the number of single cells, the cross-sectional area of ​​the battery stack core, and the battery stack encapsulation load value is obtained; where P is the critical encapsulation load value of the battery stack; M and Q are both constants; μ is the length coefficient, which is a constant related to the constraint method at both ends of the battery stack; N is the number of single cells; b is the width of the battery stack core; L is the height of the battery stack core; and A is the cross-sectional area of ​​the battery stack core.

[0061] The empirical aspect ratio of the battery stack is a ratio set by technicians based on experience. Substituting this empirical aspect ratio into the formula: A graph showing the relationship between the number of individual cells, the cross-sectional area of ​​the battery stack core, and the battery stack encapsulation load value is obtained. From this graph, the critical encapsulation load value of the battery stack can be determined based on different numbers of individual cells and different cross-sectional areas of the battery stack core. Therefore, the critical encapsulation load value of the battery stack can be determined based on the actual number of individual cells, the actual cross-sectional area of ​​the battery stack core, and the graph showing the relationship between the number of individual cells, the cross-sectional area of ​​the battery stack core, and the battery stack encapsulation load value.

[0062] Optionally, such as Figure 1 and Figure 2 As shown, based on the empirical cross-sectional area and formula of the battery stack core: The relationship between the number of single cells, the aspect ratio of the battery stack core, and the battery stack packaging load value was obtained.

[0063] The empirical cross-sectional area of ​​a battery stack is the cross-sectional area of ​​the battery stack determined by engineers based on experience. Substituting the empirical cross-sectional area of ​​the battery stack core into the formula: A graph showing the relationship between the number of individual cells, the aspect ratio of the battery stack core, and the battery stack encapsulation load value was obtained. From this graph, the aspect ratio of the battery stack core can be determined based on different numbers of individual cells and different battery stack encapsulation load values. Therefore, based on the critical encapsulation load value of the battery stack, the actual number of individual cells, and the graph showing the relationship between the number of individual cells, the aspect ratio of the battery stack core, and the battery stack encapsulation load value, the actual aspect ratio of the battery stack core can be determined.

[0064] Optionally, the actual encapsulation load value of the battery stack is less than the critical encapsulation load value of the battery stack. Once the length, width, and height of the battery stack core are determined, the actual encapsulation load value used to encapsulate the battery stack is the actual encapsulation load value. When the actual encapsulation load value of the battery stack exceeds the critical encapsulation load value, the battery stack will experience buckling instability, leading to overall deformation of the battery stack, or even failures such as short circuits or gas leaks.

[0065] This invention also provides a fuel cell stack, which employs the aforementioned high stability calculation method for fuel cell stacks. The fuel cell stack includes a stack core, which comprises N single cells connected in series, where 200 ≤ N ≤ 500; the cross-sectional area of ​​the stack core is A, 0.02 m². 2 ≤A≤0.168m 2 The aspect ratio of the fuel cell stack core is L / b, 4.0≤L / b≤7.5; the critical encapsulation load value of the fuel cell stack is 20kN-50kN.

[0066] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for calculating the high stability of a fuel cell stack, characterized in that, include: Determine the actual number of cells in a single cell and the actual cross-sectional area of ​​the battery stack core; Based on the actual number of individual cells, the actual cross-sectional area of ​​the battery stack core, and the relationship between the number of individual cells, the cross-sectional area of ​​the battery stack core, and the battery stack encapsulation load value, the critical encapsulation load value of the battery stack is determined. The actual aspect ratio of the battery stack core is determined based on the critical encapsulation load value of the battery stack, the actual number of individual cells, and the relationship between the number of individual cells, the aspect ratio of the battery stack core, and the encapsulation load value of the battery stack. The length, width, and height of the battery stack core are determined based on the actual cross-sectional area and the actual aspect ratio of the battery stack core. Based on the empirical aspect ratio and formula of battery stacks: The relationship between the number of single battery cells, the cross-sectional area of ​​the battery stack core, and the battery stack packaging load value is obtained. E(N) is the elastic modulus of the battery stack core; Where P is the critical encapsulation load value of the battery stack; M and Q are both constants; μ is the length coefficient; N is the number of cells per cell; b is the width of the battery stack core; L is the height of the battery stack core; and A is the cross-sectional area of ​​the battery stack core. Based on the empirical cross-sectional area and formula of the battery stack core: The relationship between the number of single cells, the aspect ratio of the battery stack core, and the battery stack packaging load value is obtained. The actual encapsulation load value of the battery stack is less than the critical encapsulation load value of the battery stack; The number of individual cells multiplied by the thickness of the individual cells equals the height of the battery stack core.

2. The method for calculating the high stability of a fuel cell stack according to claim 1, characterized in that, The critical encapsulation load value of the battery stack is inversely proportional to the square of the actual aspect ratio of the battery stack core, the critical encapsulation load value of the battery stack is inversely proportional to the actual number of cells in the single cell, and the critical encapsulation load value of the battery stack is directly proportional to the actual cross-sectional area of ​​the battery stack core.

3. A fuel cell stack, characterized in that, The high stability calculation method for fuel cell stacks according to any one of claims 1-2 is adopted, wherein the fuel cell stack includes a stack core, and the stack core includes N single cells connected in series, where 200≤N≤500.

4. The fuel cell stack according to claim 3, characterized in that, The cross-sectional area of ​​the battery stack core is A, 0.02m³. 2 ≤A≤0.168m 2 .

5. The fuel cell stack according to claim 3, characterized in that, The aspect ratio of the battery stack core is L / b, where 4.0 ≤ L / b ≤ 7.

5.

6. The fuel cell stack according to claim 3, characterized in that, The critical encapsulation load value of the fuel cell stack is 20kN-50kN.

Images