Stack-compression hardware

The function of the stack-compression hardware is to fasten stack components with a defined and homogeneous pressure. If these requirements are not accurately fulfilled, the function and the durability of the stack will be influenced negatively. The MEAs and the bipolar plates need to be fixed in accurate positions and the compression of gaskets needs to be safe and homogeneous. If the pressure is too high, it will cause mechanical failure of the membrane or of the bipolar plate. If the pressure is too low. 

Figure 12 shows an example of compact compression hardware with improved force distribution. The force is transferred to the end plate hardware by steel or plastic bands. This permits a very short distance from the stack. The band lies on a leaf spring which is nearly flat when the force is applied. As a result the force is not transferred to the end plate at a single point but over a wide area. As this area lies in the center of the plate, the deflection of the plate is much reduced. 

Assuming that the fuel cell stack is homogeneously fixed by the compression hardware, the main influence on degradation effects on the MEA is an inhomogeneous fluid distribution. If there are no influences by inhomogeneous cells, the cell with the... 

A load frame is required to provide compression to all seals. This type of hardware is potentially bulky and expensive. If (portions of the) load frame must be kept at lower temperatures than the stack itself, packaging and insulation is significantly complicated, especially if multiple stacks are to be combined for larger-capacity systems... 

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