Contents lists available at ScienceDirect Journal of Power Sources journal homepage: www.elsevier.com/locate/jpowsour Two-phase computational modelling of a membraneless microfluidic fuel cell with a flow-through porous anode Hao-Nan Wang a,b , Xun Zhu a,b,* , Biao Zhang a,b,** , Ding-Ding Ye a,b , Rong Chen a,b , Qiang Liao a,b , Pang-Chieh Sui c , Ned Djilali d a Key Laboratory of Low-grade Energy Utilization Technologies and Systems, Ministry of Education, Chongqing University, Chongqing, 400030, China b Institute of Engineering Thermophysics, School of Energy and Powering Engineering, Chongqing University, Chongqing, 400030, China c School of Automotive Engineering, Wuhan University of Technology, Wuhan, 430070, China d Department of Mechanical Engineering, and Institute for Integrated Energy Systems (IESVic), University of Victoria, P.O.Box 3055 STN CSC, Victoria, BC, V8W 3P6, Canada HIGHLIGHTS • A two-phase two-dimensional model is developed for microfluidic fuel cells. • The commonly used single-phase assumption tends to overestimate cell performance. • The gas-phase retention reduces anode reaction rate and impedes proton conduction. • The fuel crossover is found to correlate with the void fraction in microchannel. • The anode catalyst and microstructure should be improved for better performance. ARTICLE INFO Keywords: Microfluidic fuel cells Two-phase flow Mass transport Flow-through Porous anode Computational modelling ABSTRACT Membraneless microfluidic fuel cells are miniaturized and integratable power sources as compared with con- ventional fuel cells based on membrane electrode assembly. To elucidate the interaction of two-phase flow, mass transport and electrochemical reactions, a two-dimensional two-phase model is developed for the microfluidic fuel cell with a flow-through porous anode. The two-phase flow in the anode and the microchannel is formulated by the two-fluid model and mixture multiphase flow theory, respectively. The modelling results suggest that the retention of gas phase in the anode catalyst layer and microchannel can reduce the effective active area and impede the proton conduction to limit the cell performance. However, the commonly used single-phase as- sumption fails to capture these effects, resulting in overestimated performance. The fuel crossover shows an opposite trend as compared with that predicted by the previous single-phase model, and is found to correlate with the two-phase flow in the microchannel. The flow rates of fuel and electrolyte on the fuel transport and gas- phase removal are also discussed. The present work highlights the significance of two-phase effects in the modelling of microfluidic fuel cells, and provides insights into the two-phase flow and mass transfer for future development and operation. 1. Introduction Membraneless microfluidic fuel cell (MMFC) is a competitive micro- power source for point-of-care devices and microelectronics [1–3]. Benefited from the co-laminar flow in microchannels, the anode and cathode in MMFCs can be separated without a physical membrane [4,5], making MMFCs adaptive and integratable as compared with conventional micro fuel cells based on membrane electrode assembly. Not only the cell configuration but also the fuel/oxidant combination can be readily tuned for better performance and integration [6,7], with little concern about the critical issues regarding the membrane [8]. Because of these advantages, MMFCs had received ever-increasing https://doi.org/10.1016/j.jpowsour.2019.02.081 Received 14 November 2018; Received in revised form 15 February 2019; Accepted 24 February 2019 * Corresponding author. Key Laboratory of Low-grade Energy Utilization Technologies and Systems, Ministry of Education, Chongqing University, Chongqing, 400030, China. ** Corresponding author. Key Laboratory of Low-grade Energy Utilization Technologies and Systems, Ministry of Education, Chongqing University, Chongqing, 400030, China. E-mail addresses: zhuxun@cqu.edu.cn (X. Zhu), zhangbiao@cqu.edu.cn (B. Zhang). Journal of Power Sources 420 (2019) 88–98 0378-7753/ © 2019 Elsevier B.V. All rights reserved. T