Search

Assembly error, misalignment of components, is inevitable in the fabrication of proton exchange membrane (PEM) fuel cells. It will induce complex and contradictory effects, such as the higher contact resistance and better gas permeability, making it difficult to evaluate the error tolerance. These coupled impact on the performance of fuel cell needs to be clarified. This study establishes a performance prediction model considering the contact resistance between bipolar plate (BPP) and gas diffusion layer (GDL), deformation of membrane electrode assembly (MEA), and distribution of porosity and permeability in GDL to analyze the effect of assembly error. Assembly error brings better performance due to the higher porosity, permeability, and a more uniform distribution of oxygen. However, contact resistance also increases. Cases with narrow channels, thinner GDL, and lower compression ratios are more susceptible to assembly error, mainly manifested in the higher contact resistance, lower porosity and permeability growth, and less oxygen distribution improvement. Cases with wider channels, thicker GDL, and higher compression ratios have a higher tolerance for assembly error. Considering that contact resistance has a greater impact in most cases, assembly error needs to be avoided. The tolerance of assembly error is proposed to guide the fuel cell fabrication. • A method for analyzing the effects of assembly error on performance is proposed. • Results of the assembly model are input into the performance prediction model. • MEA deformation, the distribution of GDL porosity and permeability are considered. • Effects of channel width, GDL thickness, and compression ratio are analyzed. • Tolerance of assembly error under different conditions is proposed. [ABSTRACT FROM AUTHOR]

Metallic bipolar plates (BPPs) are promising candidates for replacing conventional carbon-based BPPs. However, manufacturing errors are unavoidable on metallic BPPs due to the characteristics of fabrication processes. This study is conducted to further develop tolerance design method for dimensional error and assembly error based on the contact behavior model proposed in our previous work. Contact pressure distribution, contact resistance and gas diffusion layer (GDL) porosity are used as the evaluation indexes combined by desirability function method. Based on the contact behavior model, effect of dimensional error is substituted into the model by Monte Carlo Simulation, and misalignment between the upper plate and lower plate is included in the model to obtain the effect of assembly error. It is found that dimensional error and assembly error contribute to uneven pressure distribution, larger contact resistance and higher GDL porosity. The acceptable maximum dimensional error of 0.007, 0.012, 0.010 mm and assembly error of 0.080, 0.10, and 0.060 mm are recommended for the fuel cells with the channel widths of 1.0, 2.0 and 4.0 mm, respectively. This methodology developed is beneficial to the understanding of the effect of dimensional error and assembly error, and effective supplement to fabrication management of metallic BPPs. Image 1 • Tolerance design method for fabrication error of metallic BPPs is introduced. • Response variables are almost in linear rise with increasing the dimensional error. • Assembly error smaller than 0.05 mm contributes little to the response variables. • Dimensional error of 7, 12, 10 μm considered acceptable for channels of 1, 2, 4 mm. • Assembly error of 80, 100, 60 μm considered acceptable for channels of 1, 2, 4 mm. [ABSTRACT FROM AUTHOR]