Nuclear Instruments and Methods in Physics Research A 542 (2005) 134–141 Study of water distribution and transport in a polymer electrolyte fuel cell using neutron imaging N. Pekula, K. Heller, P.A. Chuang, A. Turhan, M.M. Mench, J.S. Brenizer à , K. U ¨ nlu¨ Pennsylvania State University, 138, Reber Building, University Park, PA 16803, USA Available online 19 February 2005 Abstract A procedure to utilize neutron imaging for the visualization of two-phase flow within an operating polymer electrolyte fuel cell has been developed at the Penn State Breazeale Nuclear Reactor. Neutron images allow us to visualize the liquid water inside the flow channel (0.5 mm deep) and gas diffusion media (200 mm thick) in real operating conditions. The current temporal and spatial resolution for radioscopy is approximately 30 frames/s and 129 mm/pixel in a 50 cm 2 image area. Continuous digital radioscopy can be recorded for 45 min. The determination of water volume within the cell has been enabled by referencing a calibration look-up table that correlates neutron attenuation to an equivalent liquid water thickness. It was found that liquid water tends to accumulate at specific locations within the fuel cell, depending on operating conditions. Anode flow channel blockage was observed to occur at low power, while higher power conditions resulted in more dispersed distribution of liquid droplets. Under high- power conditions, liquid water tended to accumulate along or under the channel walls at 1801 turns, and radioscopy revealed that individual liquid droplet velocities were several orders of magnitude less than that of the reactant flow, indicating a slug-flow regime up to at least 1 A/cm 2 . r 2005 Elsevier B.V. All rights reserved. PACS: 42.30.Va; 42.79.Pw; 84.60.Dn Keywords: Fuel cell; Neutron radiography; Water management; Imaging 1. Introduction Recently, fuel cell technology has gained high interest in stationary, portable, and automotive applications, due to vast improvements in perfor- mance, increased environmental concern, as well as a need for petroleum-free power sources. Due to its high efficiency, low operating temperature (30–80 1C), and rapid evolution over the past decade, the polymer electrolyte fuel cell (PEFC) is currently under intense research and development. ARTICLE IN PRESS www.elsevier.com/locate/nima 0168-9002/$ - see front matter r 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.nima.2005.01.090 à Corresponding author. Tel.: +1 814 863 6384; fax: +1 814 863 4840. E-mail address: brenizer@engr.psu.edu (J.S. Brenizer).