Measurement and estimation of species distribution in a direct methanol fuel cell Selahattin Celik, Mahmut D. Mat* Nigde University, Mechanical Engineering Department, 51100 Nigde, Turkey article info Article history: Received 30 July 2009 Received in revised form 13 September 2009 Accepted 19 September 2009 Available online 8 January 2010 Keywords: Direct methanol fuel cell Methanol concentration Performance measurement Mathematical modeling abstract Determination of methanol concentration in a direct methanol fuel cell is crucial for design improvement and performance enhancement. Methanol and water concentrations in a direct methanol fuel cell are experimentally and numerically investigated. In the experimental program, a single cell direct methanol fuel cell is developed and an experi- mental setup is devised to measure methanol and water concentrations and performance of the cell depending on operating conditions. In theoretical program a mathematical model which includes fluid flow, species distribution, electric field and electrochemistry is adapted and numerically solved. The results showed that the performance of a Direct Methanol Fuel Cell (DMFC) is mainly influenced by operating temperature. A large drop in methanol concentration methanol is measured at the inlet section of cell. The mathe- matical model is found to satisfactorily capture main physics involved in a DMFC. ª 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved. 1. Introduction There is a growing interest to direct methanol fuel cells due to elimination of hydrogen storage, high energy density of methanol, modularity, vibration free and silent operation and its high potential as a power source in portable electronic applications. There have been many theoretical and experimental works in recent years on Direct Methanol Fuel Cell (DMFC) to understand mechanisms and operational characteristics. Operation of DMFC is complicated since there are many physical mechanisms such as fluid flow, mass transfer, heat transfer as well as electrochemical reactions occurs at the same time. The CO 2 bubbles generated during the electro- chemical reactions and liquid and gas flow in porous gas diffusion and catalyst layers further complicates the problem. The analysis of behavior of gaseous and liquid phases and concentration distribution of methanol-water mixture in a DMFC are essential in design and performance improvement. Although a number of experimental studies have concentrated on distribution of gas and liquid flow, determination of methanol concentration in a DMFC cell and their effect on the performance have not been considered. Therefore the aim of this study is experimental and numerical determination of methanol distribution during the operation of a DMFC depending on a range of parameters such as temperature, flow rates, operating conditions. Visualization of DMFC operation provide useful tool understanding the gas-liquid flow CO 2 evolution and gas dynamics. The studies on the visualization usually employ a transparent backing plates and video-microscopy method- ology. Joakim et al [1] developed a transparent DMFC cell and monitored CO 2 evolution, bubble growth and distribution with a video-microscopy method and developed a map for gas distribution in the cell. The investigation showed that the gas concentration increased along the cell. Lu and Wang [2] also employed a transparent DMFC cell and investigated CO 2 distribution in a range of operating parameters such as * Corresponding author. Tel.: þ90 3882252251; fax: þ90 3882250112. E-mail addresses: scelik@nigde.edu.tr (S. Celik), mdmat@nigde.edu.tr (M.D. Mat). Available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/he 0360-3199/$ – see front matter ª 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.ijhydene.2009.09.057 international journal of hydrogen energy 35 (2010) 2151–2159