Two-phase flow in a proton exchange membrane electrolyzer visualized in situ by simultaneous neutron radiography and optical imaging

WOS: 000319232500036In proton exchange membrane (PEM) electrolyzers, oxygen evolution in the anode and flooding due to water cross-over in the cathode yields two distinct two-phase transport conditions which strongly affect the performance. Two-phase transport in an electrolyzer cell is visualized by simultaneous neutron radiography and optical imaging. Optical and neutron data are used in a complementary manner to aid in understanding the two-phase flow behavior. Two different patterns of gas-bubble evolution and departure are identified: periodic growth/removal of small bubbles vs. prolonged blockage by stagnant large bubbles. In addition, the bubble distribution across the active area is not uniform due to combined effects of buoyancy and proximity to the inlet. The effects of operating parameters such as current density, temperature and water flow rate on the two-phase distribution are investigated. Higher water accumulation is detected in the cathode chamber at higher current density, even though the cathode is purged with a high flow rate of N-2. The temperature is found to affect the volume of water; higher temperature yields less water and more gas volume in the anode chamber. Higher temperature also enhanced the water transport in the cathode chamber. Finally, water transported through the membrane to the cathode reduced the cell performance by limiting the hydrogen mass transport. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.Scientific and Research Council of Turkey (TUBITAK); National Science Foundation [CBET-0748063]; U.S. Department of Commerce; NIST Radiation and Biomolecular Physics Division; Director's Office of NIST; NIST Center for Neutron Research; Department of Energy [DEAI01-01EE50660]Omer F. Selamet would like to thank the Scientific and Research Council of Turkey (TUBITAK) for financial support for this research. Financial support for this work from the National Science Foundation (CBET-0748063) is gratefully acknowledged. This work was supported by the U.S. Department of Commerce, the NIST Radiation and Biomolecular Physics Division, the Director's Office of NIST, the NIST Center for Neutron Research, and the Department of Energy through Interagency Agreement No. DEAI01-01EE50660. We thank professors Ajay K. Prasad and Suresh G. Advani of the University of Delaware for their assistance with the experimental setup and equipment loan, Eli Baltic of the NIST for his help during the experiments in the NIST, and Richard S. Fu for his help with data analysis

In-situ two-phase flow investigation of Proton Exchange Membrane (PEM) electrolyzer by simultaneous optical and neutron imaging

11th Polymer Electrolyte Fuel Cell Symposium (PEFC) Under the Auspices of the 220th Meeting of the ECS -- OCT, 2011 -- Boston, MAWOS: 000309598800030In proton exchange membrane (PEM) electrolyzers, oxygen evolution in the anode and flooding due to water cross-over results in two distinct two-phase transport conditions, and these two phenomena were found to strongly affect the performance. A comprehensive understanding of two-phase flow in PEM electrolyzer is required to increase efficiency and aid in material selection and flow field design. In this study, two-phase transport in an electrolyzer cell is visualized by simultaneous neutron radiography and optical imaging. Optical and neutron data were used in a complementary manner to aid in understanding the two-phase flow behavior. The behavior of the gas bubbles was investigated and two different gas bubble evolution and departure mechanisms are found. It was also found that there is a strong non-uniformity in the gas bubble distribution across the active area, due to buoyancy and proximity to the water and purge gas inlet.ECS, Energy Technol (ETD), Phys & Analyt Electrochem (PAED), Battery (BATT), Ind Electrochem & Electrochem Engn (IEEE), Corros (CORR)Scientific and Research Council of Turkey (TUBITAK); National Science Foundation [CBET-0748063]; U.S. Department of Commerce; NIST Ionizing Radiation Division; Director's Office of NIST; NIST Center for Neutron Research; Department of Energy [DEAI01-01EE50660]Omer F. Selamet would like to thank the Scientific and Research Council of Turkey (TUBITAK) for financial support for this research. Financial support for this work from the National Science Foundation (CBET-0748063) is gratefully acknowledged. We thank professors Ajay K. Prasad and Suresh G. Advani of the University of Delaware for their assistance with the experimental setup. The authors thank Elias Baltic of the NIST for his technical help during the experiments in the NIST. This work was supported by the U.S. Department of Commerce, the NIST Ionizing Radiation Division, the Director's Office of NIST, the NIST Center for Neutron Research, and the Department of Energy through Interagency Agreement No. DEAI01-01EE50660. We also thank to Richard S. Fu for his help during the data analysis

Antineutrophil cytoplasmic antibody-associated vasculitis, update on molecular pathogenesis, diagnosis, and treatment

Farid Arman,1 Marina Barsoum,1 Umut Selamet,1 Hania Shakeri,1 Olivia Wassef,1 Mira Mikhail,2 Anjay Rastogi,1 Ramy M Hanna1 1Department of Medicine, Division of Nephrology, UCLA David Geffen School of Medicine, Los Angeles, CA, USA; 2College of Biological Sciences, Biola University, La Mirada, CA, USA Abstract: Circulating antineutrophil cytoplasmic antibodies (ANCAs) are the central pathogenic mechanism for a group of systemic and renal syndromes called the ANCA-associated vasculitis (AAV). The nomenclature has changed from eponymous labeling to granulomatosis with polyangiitis, eosinophilic granulomatosis with polyangiitis, and microscopic polyangiitis. These syndromes predominantly affect the pulmonary and renal systems. We also review the molecular pathology behind ANCAs and associated antigens and infections. Various clinical presentations, the multiple target organs affected, and diagnostic challenges involved in identifying these diseases are discussed. Treatment updates are also provided with regard to new studies and the now standard use of anti-CD-20 monoclonal antibodies as first-line therapy in all but the most aggressive presentations of this disease. Maintenance regimens and monitoring strategies for relapse of vasculitis and associated systemic complications are discussed. Keywords: proteinuria, glomerulonephritis, ANCA associated vasculitis, rituximab, P-ANCA, C-ANC