Ex-situ experimental studies on serpentine flow field design for redox flow battery systems

Electrolyte distribution using parallel flow field for redox flow battery (RFB) applications shows severe non-uniformity, while the conventional design of using the carbon felt itself as the flow distributor gives too high pressure drop. An optimized flow field design for uniform flow distribution at a minimal parasitic power loss is therefore needed for RFB systems. Since the materials and geometrical dimensions in REBs are very different from those used in fuel cells, the hydrodynamics of the flow fields in RFBs is likely to be very different. In the present paper, we report on a fundamental study of the hydrodynamics of a serpentine flow field relevant to RFB applications. The permeability of the porous medium has been measured under different compression ratios and this is found to be in the range of 5-8 x 10(-11) m(2). The pressure drop in two serpentine flow fields of different geometric characteristics has been measured over a range of Reynolds numbers. Further analysis using computational fluid dynamics simulations brings out the importance of the compression of the porous medium as an additional parameter in determining the flow distribution and pressure drop in these flow fields. (C) 2013 Elsevier B.V. All rights reserved.