Design considerations for testing freeform PEM fuel cells
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A proton exchange membrane (PEM) fuel cell test platform was functionally evaluated and redesigned in terms of its "test system" and "stack fixture" constituents so as to accommodate novel fuel cell stacks manufactured with selective laser sintering (SLS) technology. Structured engineering judgment, development of unique design variables, the Nai number and the gas demand rate, and identification of an appropriate computation algorithm paved the way for prescribing the best-suited test station configuration. The final test system had operational capabilities of 600W, 120 A, and 60 V, and could support gas flow rates up to 3 sLpm for hydrogen and 10 sLpm for air. The stack design space characteristic of the Nai numbers was bounded by 4.4cell·A and 197.1cell·A, as per the limitations of the test system. Principles of design for flexibility (DFF) and a modified version of change modes effects analysis (CMEA) were used as guidance for redesigning the stack fixture. The novel "cable-compressor" fixture concept displayed a 20% improvement in the overall change potential number, and 38% in the specific modules targeted during the design process. As a result, assembly and operation of a freeform fuel cell stack prototype was achieved, albeit with persistent leakage issues arising from the surface roughness and fixture compression mechanism. With the new fixture, highly-curved stacks of various lengths and membrane sizes (up to 125 cm2) could be accommodated.