Gas flow field with obstacles for PEM fuel cells at different operating conditions Muhittin Bilgili a,b,* , Magdalena Bosomoiu a , Georgios Tsotridis a a Institute for Energy and Transport, Joint Research Center, European Commission, NL-1755 ZG Petten, The Netherlands b Department of Mechanical Engineering, Faculty of Engineering, Gazi University, Maltepe, 06570 Ankara, Turkey article info Article history: Received 23 July 2014 Received in revised form 21 November 2014 Accepted 27 November 2014 Available online 20 December 2014 Keywords: PEM fuel cell Numerical modeling Gas flow field Obstacle Operating condition abstract In proton exchange membrane fuel cells (PEMFCs) laminar flow inside anode and cathode gas channels can be disrupted by using obstacles. By arranging these obstacles near to the exit of the gas channels concentration losses due to hydrogen and oxygen consumption inside the channel will be decreased. Using a three dimensional computational model, numerical simulations are performed to investigate performance of PEMFCs containing obstacles in the anode and cathode gas flow channels. These simulations were conducted at different operating conditions (stoichiometry, relative humidity and temperature) to clarify the effects of the obstacles at specified conditions. The simulations show that the obstacles inside the gas flow channels improve the concentration distribution along the channels and the transport of the reactant gases through the gas diffusion layer (GDL). As a result, the electrochemical reaction is improved and higher cell voltage is obtained at high current densities. Copyright © 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. Introduction Fuel cell (FC) systems are promising candidates for near future and sustainable energy conversion. Developed countries are trying to use fuel cell technology especially in transportation and also stationary applications. FCs are expected to play an important role in future power generation facilities. The dif- ferences among the existing categories of FC systems are mainly based on the type of electrolyte and operating condi- tions. Some of the important features of proton exchange membrane (PEM) fuel cells are: easy start-up, high power density, high efficiency and being usable in mobile applications. The PEM fuel cell may be operated from pres- sures near ambient to about 6 atm, and at temperatures be- tween 50 and 90  C. Higher current densities are achievable associated with a voltage gain at higher pressures. For PEMFCs operating parameters are also an important issue, therefore for a new design or a new arrangement, operating parameters have to be taken into account carefully [1,2]. Dong et al. [3] tried to disrupt the laminar flow by locating obstacles in the gas channels of the oxidant flow field. By these obstacles laminar flow is changed to turbulent flow therefore enhancing the transfer of oxygen to the membrane electrode assembly in the fuel cell. As more oxygen enters the reaction, more energy will be delivered. Therefore, the * Corresponding author. Department of Mechanical Engineering, Faculty of Engineering, Gazi University, Eti Mah. Yukselis Sok. No: 5, Maltepe, 06570 Ankara, Turkey. Tel.: þ90 312 582 3404; fax: þ90 312 231 9810. E-mail address: bilgili@gazi.edu.tr (M. Bilgili). Available online at www.sciencedirect.com ScienceDirect journal homepage: www.elsevier.com/locate/he international journal of hydrogen energy 40 (2015) 2303 e2311 http://dx.doi.org/10.1016/j.ijhydene.2014.11.139 0360-3199/Copyright © 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.