Mass transfer characteristics of the hydrophilic membrane with the isolation of heat transfer effect by isothermal bath Hyunwoo Tak a , Jinwon Yun a , Jaeyoung Han a , Sangseok Yu b, * a Mechanical Engineering, Graduate School, Chungnam National University, 79 Daehangno, Yuseong-gu, Daejon 305-764, Republic of Korea b Chungnam National University, 79 Daehangno, Yuseong-gu, Daejon 305-764, Republic of Korea article info Article history: Received 22 April 2013 Received in revised form 4 September 2013 Accepted 25 October 2013 Available online 23 November 2013 Keywords: PEMFC Membrane humidifier Mass transfer Reynolds number Isothermal bath abstract The efficiency and lifetime of a proton exchange membrane fuel cell (PEMFC) system is critically affected by the humidity of incoming gas which should be maintained properly for normal operating conditions. But the experimental characteristics of the humidifier are rarely reported. Water transport through the hydrophilic membrane is a coupled phe- nomenon of heat and mass transport. In this study, a laboratory scale test bench is designed to investigate the characteristics of water transport through the hydrophilic membrane. The mass transfer capability of the hydrophilic membrane is evaluated over various flow rates, temperature, pressure, and flow arrangements. In the experiment, the test bench is submerged in a constant temperature bath in order to isolate the effect of temperature variation between dry air and humid air. The results show the water transport of the hydrophilic membrane is significantly affected by operating temperature and operating pressure. Additionally, the flow arrangement demonstrates a minor effect but it should be considered along with the heat transfer effect. Copyright ª 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. 1. Introduction A proton exchange membrane fuel cell (PEMFC) has attractive features as an automotive power source including high effi- ciency, fast start-up, very low noise, compact and easy pack- aging, and no air pollution. Another PEMFC application is as a residential power generation system, due to its dual capability of heat and power generation. Because of the intrinsic nature of its electrolyte, the PEMFC should be well humidified for high performance and reliable operation. Many humidification systems have been studied in the past [1e7] to determine an appropriate system for fuel cells. A membrane humidifier has been widely used due to its high performance capability with no parasitic power loss. The membrane of the humidifier has properties similar to the membrane electrolyte, but its hydrophilic capability is enhanced, so that the transport of water vapor can be facili- tated from the wet air side to the dry air side. Even though the humidification of PEMFC is a very signif- icant issue affecting durability and high efficiency, few re- searches have been reported in the area of commercial humidifier modeling. The physical aspect of a humidifier is very complicated, given that heat and mass transfer are simultaneously involved in the transport of vapor from the * Corresponding author. Tel.: þ82 42 821 5646; fax: þ82 42 822 5642. E-mail addresses: sangseok@cnu.ac.kr, stonex1004@hotmail.com (S. Yu). Available online at www.sciencedirect.com ScienceDirect journal homepage: www.elsevier.com/locate/he international journal of hydrogen energy 39 (2014) 958 e965 0360-3199/$ e see front matter Copyright ª 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ijhydene.2013.10.140