Effect of Clamping Load on the Performance and Contact Pressure of PEMFC Stack 2018-01-1310
In the assembling process of proton exchange membrane fuel cell (PEMFC) stack, the clamping load is known to have direct effect on the contact pressure of interfaces. Compression on the membrane electrode assembly (MEA) results in change in gas diffusion layer (GDL), porosity and electrical resistance, thus affecting the performance, durability and reliability of the PEMFC stack. In this paper, the relation between clamping load and performance of PEMFC stack was obtained by experimental study, and the influence of clamping load on the contact pressure of MEAs was analyzed by finite element analysis. The performance test rig was established and the approach of polarization curve testing was introduced. Both the effect of magnitude and distribution of the bolt torques on the performance were taken into account. The finite element model was adopted to figure out the magnitude and uniformity of contact pressure of MEAs, which provides a new angle to understand the experimental results. Results show that the clamping load has significant effect on the performance of the stack, and at single bolt torque of 10 Nm, the ohmic resistance is extremely large and the overall performance is severely affected, while the impact of bolt torque distribution is considerably small and can be neglected. The magnitude of contact pressure does not vary with the position of MEAs, and it is linearly correlated to the clamping load. The uniformity of contact pressure not only change with the position of MEAs, but also varies with the size of clamping load. This paper focuses on the difference of performance and contact pressure of PEMFC stack under varied clamping load conditions, which provides a reference for the assembling method of PEMFC stack.