02107nas a2200229 4500008004100000022001400041245007500055210006900130260010600199300001400305490000700319520130400326653000901630653001501639653003601654653002101690653001701711100001401728700001501742700001801757856010201775 2007 eng d a0013-468600aDMFC at low air flow operation: study of parasitic hydrogen generation0 aDMFC at low air flow operation study of parasitic hydrogen gener aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLANDbPERGAMON-ELSEVIER SCIENCE LTDcMAY a6060-60670 v523 a
In this paper, the effect of hydrogen generation in direct methanol fuel cells (DMFC) is described. Under certain operating conditions hydrogen generation occurs in DMFC causing an additional methanol consumption and a decrease of the cell voltage. For the present experiments a segmented cell with an active area of 244 cm 2 is used. The cell has 196 segments which are regularly distributed on the whole area. By this experimental setup hydrogen generation was found in regions with insufficient air supply. Hydrogen generation was analyzed by systematically applying different air flow rates and detecting the local current densities. The theory for hydrogen generation is confirmed by the results obtained from the segmented cell. A correlation between open circuit voltage (OCV), air flow rate and hydrogen generation was observed. Furthermore, half-cell measurements with different methanol concentrations were performed and used for analyzing the processes during hydrogen generation. The work clearly indicates the importance of sufficient cathode air supply for DMFC. Starved cathode areas not only do not contribute to the overall current generation but in addition reduce the power and efficiency by the parasitic generation of hydrogen. (C) 2007 Elsevier Ltd. All rights reserved.
10aDMFC10aEfficiency10aelectrolytic hydrogen evolution10aoxygen depletion10aside-effects1 aDohle, H.1 aMergel, J.1 aGhosh, P., C. uhttp://library.ncl.res.in/content/dmfc-low-air-flow-operation-study-parasitic-hydrogen-generation