How to Assemble a High-performance Fuel Cell Stack?
How to Assemble a High-performance Fuel Cell Stack? Cheersonic
The transformation of any product from an idea into a real product is inseparable from manufacturing, and there will be errors in the manufacture of any product. It will never be possible to process a ruler that is absolutely equal to one meter, only a ruler that is almost one meter.
The same is true for fuel cells. There are errors in the size and matching size of the components of the stack. These errors will have different effects on the performance of the fuel cell stack. Strict process control is required to determine the impact of process factors on the performance of the stack. Control to a minimum while improving product consistency.
The materials of the stack include rigid parts such as end plates and pole plates, as well as flexible parts such as MEA and sealing lines. These parts will be subjected to various forces during the assembly process and after the finished product, including external tightening forces. It also includes the inner diffusion layer, the elastic force of the sealing line, the expansion force of the membrane after water absorption, and so on.
When the end plate is fastened with bolts, the surrounding area will be greatly deformed, and the center will bulge, which will cause uneven distribution of the compression force in the single cell near the end plate. The compression force distribution is gradually uniform. The distribution of the pressing force has an important influence on the contact resistance and current density distribution of the fuel cell. Therefore, there must be strict process requirements and testing standards for the deformation of the stack end plate after assembly.
Due to the influence of the stamping process, the center part of the fuel cell metal bipolar plate is often thicker than the edge. The accumulation of errors in these processes also affects the assembly of the fuel cell. A large number of test verifications and calculations are needed to determine the size of the plate. Error requirements, so that the force distribution of the active area of the fuel cell is uniform.
In order to better analyze, detect and control process parameters, some professional testing equipment is necessary. In terms of stack assembly, it is necessary to be able to control the compression distance and pressing force of stack assembly. Generally, screw-driven stacking equipment has better precision control. In addition, professional tooling equipment is required to ensure that the stack is assembled during the assembly process. The position error between the parts and the overall shape and position error.
The inspection of the geometrical tolerances of the stack after assembly can be measured by three-coordinates to complete the quality control of the assembly process. For parts with complex shapes and structures such as bipolar plates, the measurement size can also be completed with the help of optical equipment.
The test of the compression force inside the fuel cell can be measured by traditional pressure-sensitive developing paper, and the compression force in different cells of the stack and in different parts of the single cell can be observed through the shade of color, so as to assist the designer to improve the process parameters and adjust the product design. You can also use the online matrix pressure sensor to perform a real-time pressure change test, and you can see the dynamic change of the pressure distribution.
As the output of fuel cell products continues to increase, product quality control will become more and more strict. It is necessary to thoroughly study the impact of various process parameters on product performance and determine reasonable product process standards.
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