A solid oxide fuel cell bipolar plate connector

Abstract

The present invention discloses a bipolar plate connector for a solid oxide fuel cell, belonging to the field of fuel cells, which includes a plate body. A front flow field is provided on the front surface of the plate body, and a back flow field is provided on the back surface of the plate body. The front flow field is divided into four first flow fields with the same structure, and the back flow field is divided into four second flow fields with the same structure. The first flow field and the second flow field corresponding directly below the first flow field are rotationally symmetric structures. An L-shaped flow channel is provided in the first flow field, and gas inlets and outlets are provided at both ends of the L-shaped flow channel. The reaction gas enters the L-shaped flow channel through one of the gas inlets and outlets and flows out through the other gas inlet and outlet. The bipolar plate connector for the solid oxide fuel cell of the present invention has a simple structure and is provided with an L-shaped flow channel, which makes the temperature in the stack lower and more evenly distributed, reduces the temperature gradient in the solid fuel cell, and improves the service life of the battery.

Description

Technical Field

[0001] The present invention belongs to the field of solid oxide fuel cells, and more specifically, relates to a bipolar plate connector for a solid oxide fuel cell. Background Art

[0002] At present, bipolar plate connectors have been widely used in solid oxide fuel cell stacks. Although the thermal conductivity of bipolar plate connectors is higher than that of ceramic connectors, in order to ensure the safe operation of the stack, the intake air needs to be preheated to about 700 °C by an external thermal balance system before entering the stack. At the same time, due to a large amount of heat generated by the stack during power generation, a large amount of air needs to be introduced to cool it. And during long-term operation, especially for large-sized batteries or high-power density operation, the temperature distribution in the stack is uneven, and the temperature gradient in the battery reaction area of the stack will become larger and larger, even reaching a temperature difference of more than 150 °C, resulting in a significant increase in the thermal stress in the stack and the battery area. Under the action of thermal stress, the positive electrode electrolyte negative electrode structure will undergo delamination and fission, while accelerating the attenuation of battery performance and reducing the reliability of sealing materials, and reducing the service life of the battery. Summary of the Invention

[0003] Aiming at the defects of the prior art, the purpose of the present invention is to provide a bipolar plate connector for a solid oxide fuel cell, aiming to solve the problems of uneven temperature distribution and large temperature gradient in the battery reaction area.

[0004] To achieve the above object, the present invention provides a bipolar plate connector for a solid oxide fuel cell, including a plate body. A front flow field is provided on the front surface of the plate body, and a back flow field is provided on the back surface of the plate body; the front flow field is divided into four first flow fields with the same structure, the back flow field is divided into four second flow fields with the same structure, and the first flow field and the second flow field corresponding directly below the first flow field are rotationally symmetric structures; an L-shaped flow channel is provided in the first flow field, and gas inlets and outlets are provided at both ends of the L-shaped flow channel. The reaction gas enters the L-shaped flow channel through one of the gas inlets and outlets and flows out through the other gas inlet and outlet.

[0005] Furthermore, the overall flow direction of the gas in the front flow field is counterclockwise or clockwise.

[0006] Furthermore, the overall flow direction of the gas in the back flow field is the same as or opposite to the overall flow direction of the gas in the front flow field.

[0007] Furthermore, the outer dimension of the plate body is between 20 mm × 20 mm and 200 mm × 200 mm.

[0008] Furthermore, the height of the L-shaped flow channel is between 0.5 mm and 8 mm.

[0009] Furthermore, the distance from the gas inlet / outlet to the L-shaped flow channel is 10 mm - 100 mm.

[0010] Furthermore, the thickness of the plate body is between 1 mm and 10 mm.

[0011] Furthermore, the shape of the gas inlet / outlet is polygonal or circular.

[0012] A temperature simulation method for a solid oxide fuel cell bipolar plate connector, comprising the following steps:

[0013] S1. Establish three-dimensional geometric models of a co-flow parallel flow field, a counter-flow parallel flow field, a staggered flow field, and an L-shaped flow field, and establish corresponding gas flow and electrochemical models;

[0014] S2. Use the finite volume method to perform simulation calculations on the gas flow models and electrochemical models corresponding to the co-flow parallel flow field, the counter-flow parallel flow field, the staggered flow field, and the L-shaped flow field;

[0015] S3. Calculate the temperature distribution data and temperature gradient data of each gas flow model and electrochemical model at different current densities;

[0016] S4. Analyze the temperature distribution data and temperature gradient data and draw a temperature difference line graph of the co-flow parallel flow field, the counter-flow parallel flow field, the staggered flow field, and the L-shaped flow field.

[0017] Through the above technical solutions conceived by the present invention, compared with the prior art, since the front flow field and the back flow field of the bipolar plate connector are each divided into four flow fields with the same structure, an L-shaped flow channel is provided in each flow field, and two air inlets / outlets are provided in each flow field corresponding to the L-shaped flow channel, and each flow field region corresponds to its own gas flow path, the gas flow efficiency is faster than that of the gas flowing through the same gas path in the flow field region, the temperature in the flow field region can be reduced, and at the same time, the temperature distribution in the stack is made more uniform, avoiding too large a temperature gradient in the stack and improving the service life of the stack. Description of the Drawings

[0018] Figure 1 is a schematic structural diagram of a solid oxide fuel cell bipolar plate connector provided by the present invention;

[0019] Figure 2 is a temperature distribution diagram of a solid oxide fuel cell bipolar plate connector provided by the present invention:

[0020] Figure 3 is a temperature gradient diagram of a solid oxide fuel cell bipolar plate connector provided by the present invention:

[0021] Figure 4It is the temperature difference broken line graph of the bipolar plate connector of the solid oxide fuel cell provided by the present invention.

[0022] The structures corresponding to the respective numerical markings in the drawings are: 1 - plate body, 11 - first flow field, 111 - first L-shaped flow channel, 112 - first gas inlet and outlet, 122 - second gas inlet and outlet. Specific embodiments

[0023] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0024] Refer to Figure 1 , the present invention provides a bipolar plate connector for a solid oxide fuel cell, including a plate body 1. The front surface of the plate body 1 is provided with a front flow field, and the back surface of the plate body is provided with a back flow field; the front flow field is divided into four first flow fields 11 with the same structure, and the back flow field is divided into four second flow fields with the same structure. Each first flow field 11 corresponds to a second flow field directly below it, and the corresponding first flow field 11 and second flow field are rotationally symmetric structures; the first flow field 11 is provided with a first L-shaped flow channel 111, and both ends of the first L-shaped flow channel 111 are provided with first gas inlets and outlets 112. The reaction gas enters the first L-shaped flow channel through one of the gas inlets and outlets and flows out through the other gas inlet and outlet. Similarly, the first flow field is provided with a second L-shaped flow channel, and both ends of the second L-shaped flow channel are provided with second gas inlets and outlets 122. The reaction gas enters the first L-shaped flow channel through one of the gas inlets and outlets and flows out through the other gas inlet and outlet.

[0025] The overall flow direction of the gas in the front flow field is counterclockwise or clockwise. Similarly, the overall flow direction of the gas in the back flow field is counterclockwise or clockwise. It can be seen from this that the overall flow direction of the gas in the back flow field and the overall flow direction of the gas in the front flow field are the same or opposite, that is, there are four cases for the overall flow paths of the gas in the front flow field and the back flow field.

[0026] In order to be conveniently applied to different-sized stacks, the outer dimensions of the bipolar plate connector are between 20 mm × 20 mm and 200 mm × 200 mm. Preferably, the outer dimensions are 30 mm × 30 mm; at the same time, in order to facilitate processing, the height of the first L-shaped flow channel and the second L-shaped flow channel is between 0.5 mm and 8 mm, and the plate thickness of the plate body 1 is between 1 mm and 10 mm.

[0027] When the gas flows in each flow field region, the distance from the gas inlet and outlet to the L-shaped flow channel can be adjusted according to the power of the stack, and the distance is between 10 mm and 100 mm. At the same time, the shape of the first gas inlet and outlet 112 and the second gas inlet and outlet 122 can also be adjusted to regulate the gas flow efficiency. The shape of the gas inlet and outlet is polygonal or circular. Preferably, the gas inlet and outlet is rectangular.

[0028] In order to further verify the temperature distribution of the bipolar plate connector of the solid oxide fuel cell of the present invention, the temperature distribution is simulated and analyzed, and it is compared with the bipolar plate connector with a straight flow channel. There are three types of bipolar plate connectors with a straight flow channel. According to different gas flow paths, they are a co-flow parallel flow field (the flow channels of the front flow field and the back flow field are parallel and the gas flow directions are the same), a counter-flow parallel flow field (the flow channels of the front flow field and the back flow field are parallel and the gas flow directions are opposite), and a cross-flow field (the flow channels of the front flow field and the back flow field are perpendicular and the gas flow directions are perpendicular). The bipolar plate connector of the solid oxide fuel cell of the present invention is an L-shaped flow field (the gas flow directions of the front flow field and the back flow field are opposite), and the other parameters are the same. The temperature simulation is carried out under the same experimental conditions.

[0029] Figure 2 is the temperature distribution diagram, Figure 3 is the temperature gradient diagram, where a is the co-flow parallel flow field, b is the counter-flow parallel flow field, c is the cross-flow field, and d is the L-shaped flow field; according to Figure 2 and Figure 3 the temperature distribution of each connector in, and according to the temperature distribution data and temperature gradient data, a temperature difference broken line at different current densities is drawn Figure 4 , from Figure 4 it can be seen that the temperature difference of the bipolar plate connector of the solid oxide fuel cell of the present invention is small. It can be seen that the temperature distribution in the bipolar plate connector of the solid oxide fuel cell of the present invention is more uniform, and the highest temperature is lower, and the temperature gradient is smaller. It can avoid the influence of thermal stress caused by local overheating in the stack on the performance of the stack and improve the service life of the stack. The steps of its temperature simulation method are as follows:

[0030] S1. Establish three-dimensional geometric models of the co-flow parallel flow field, the counter-flow parallel flow field, the cross-flow field, and the L-shaped flow field, and establish corresponding gas flow and electrochemical models;

[0031] S2. Use the finite volume method to perform simulation calculations on the gas flow models and electrochemical models corresponding to the co-flow parallel flow field, the counter-flow parallel flow field, the cross-flow field, and the L-shaped flow field;

[0032] S3. Calculate the temperature distribution data and temperature gradient data of each gas flow model and electrochemical model at different current densities;

[0033] S4. Analyze the temperature distribution data and temperature gradient data and plot the temperature difference broken line graphs of the co - flow parallel flow field, counter - flow parallel flow field, cross - flow field, and L - type flow field.

[0034] The maximum temperature deviation and minimum temperature deviation of each flow field obtained from the temperature gradient diagram are shown in the following table:

[0035]

[0036] Compared with the traditional direct - flow channel bipolar plate connector, the temperature deviation of the bipolar plate connector of the solid oxide fuel cell of the present invention can be reduced by at least 60%, the temperature gradient is smaller, and the temperature distribution is uniform.

[0037] Those skilled in the art can easily understand that the above - mentioned is only the preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A bipolar plate connector for a solid oxide fuel cell, characterized in that: It includes a plate body (1). A front flow field is provided on the front surface of the plate body (1), and a back flow field is provided on the back surface of the plate body (1); the front flow field is divided into four first flow fields (11) with the same structure, the back flow field is divided into four second flow fields with the same structure, and the first flow field (11) and the second flow field corresponding directly below the first flow field (11) are rotationally symmetric structures; an L-shaped flow channel is provided in the first flow field (11), and gas inlets and outlets are provided at both ends of the L-shaped flow channel. The reaction gas enters the L-shaped flow channel through one of the gas inlets and outlets and flows out through the other gas inlet and outlet.

2. The bipolar plate connector for a solid oxide fuel cell according to claim 1, characterized in that: The overall flow direction of the gas in the front flow field is counterclockwise or clockwise.

3. The bipolar plate connector for a solid oxide fuel cell according to claim 2, characterized in that: The overall flow direction of the gas in the back flow field is the same as or opposite to the overall flow direction of the gas in the front flow field.

4. The bipolar plate connector for a solid oxide fuel cell according to claim 1, characterized in that: The external dimensions of the plate body (1) are between 20mm * 20mm and 200mm * 200mm.

5. The bipolar plate connector for a solid oxide fuel cell according to claim 1, characterized in that: The height of the L-shaped flow channel is between 0.5mm and 8mm.

6. The bipolar plate connector for a solid oxide fuel cell according to claim 1, characterized in that: The distance from the gas inlets and outlets to the L-shaped flow channel is 10mm - 100mm.

7. The bipolar plate connector for a solid oxide fuel cell according to claim 1, characterized in that: The plate thickness of the plate body (1) is between 1mm and 10mm.

8. The bipolar plate connector for a solid oxide fuel cell according to claim 1, characterized in that: The shape of the gas inlets and outlets is polygonal or circular.

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