Please use this identifier to cite or link to this item:
Comparsion of Performance of Membraneless and Membrane Microfluidic Fuel Cell
|關鍵字:||Microfluidic;微流道||出版社:||機械工程學系所||引用:|| D. R. Crow: Principles and Applications of Electrochemistry, 4th ed., Wolverhampton University Press Inc., 1999.  E. Kjeang, A. G. Brolo, D. A. Harrington, N. Djilali, D.Sinton, “Hydrogen peroxide as an oxidant for microfluidic fuel cells,” J.Elechem. Soc. 154 (2007) B1220-B1226.  E. Kjeang, B. Roesch, J. McKechnie, D. A. Harri, N. Djilali, D. Sinton,“Integrated electrochemical velocimerty for microfluidic devices,”Microfluid Nanofluid. (2007) 403-416.  A. Bazylak, D. Sinton, N. Djilali, “Improved fuel utilization in microfluidic fuel cells: a computational study,” J. of Power Sources 143 (2005) 57-66.  S. H. Yang, “Design fabrication and electrochemical impedance spectroscopy for microfuel cells,” 碩士論文，國立中山大學機械系， (2005).  E. R. Choban, L. J. Markoski, A. Wieckowski, P. J. Kenis, “Microfluidic fuel cell based on laminar flow,” J. of Power Sources.128 (2004) 54 -60.  S. Hirano, J. Kim, S. Srinivasan, “High performance proton exchange membrane fuel cells with sputter-deposited Pt layer electrodes,”Electrochimica Acta. 42 (1996) 1857-1593.  S. Liu, Q. Pu, “From nanochannel-induced proton conduction enhanc -ement to a nanochannel-based fuel cell,” Nano Lett. 7 (2005) 1389-1393.  K. S. Salloum, J. R. Hayes, C. A. Friesen, J. D. Posner, “Sequential flow membraneless microfluidic fuel cell with porous electrodes,” J. of Power Sources. 180 (2008) 243-252.  E. Kjeang, B. T. Proctor, A. G. Brolo, D. A. Harrington, Djilali, “High performance microfluidic vanadium redox fuel cell,” Electrochimica Acta. 52 (2007) 4942-4946.  T. J. P. Freire , E. R. Gonzalez, ”Effect of membrane characteristics and humidification conditions on the impedance response of polymer electrolyte fuel cells,” J. of Electroanalytical Chemistry. 503 (2001) 56-78.  E. Kjeang, J. Mckechnie, D. Sinton, N. Djilali, “Planar and three-dimensional microfluidic fuel cell architectures based on graphit rod electrodes,” J. of Power Sources. 168 (2007) 379-390.  M. Wang, H. Guo, C. Ma, “Dynamic characteristics of a direct methanol fuel cell,” J. of Fuel Cell Science and Technology.3 (2006) 202-207.  K. H. Kim, J. K. Yu, H. S. Lee, J. H. Choi, S. Y. Noh, S. K. Yoon, “Preparation of Pt-Pd catalysts for direct formic acid fuel cell and their characteristics,” Korean J. Chem. Eng., 24 (2007) 518-521.  S. Y. Cha, J. M. Song, W. Lee, “Performance of proton exchange membrane fuel cell electrodes prepared by direct deposition of platinum on the membrane surface,” J. of Appiled Electrochemistry.26 (1998) 1413-1418.  http://zh.wikipedia.org/wiki  P. L. Hentall, J. B. Lakeman, G. O. Mepsted, P. L. Adock, “New materials for polymer electrolyte membrane fuel cell current collectors ,” J. of Power Sources. 80 (1999) 235-241.||摘要:||
本研究所選用的燃料為甲酸(HCOOH)，濃度固定在2M;氧化劑則為高錳酸鉀(KMnO4)，濃度範圍選定10-4~1M，流量範圍在0.1 ml/mim ~5 ml/min之間。當增加工作流體的流量時，電流密度會跟著上升，這主要是受到濃度邊界層厚度減小的影響，邊界層厚度減小，降低濃度過電位，因此電流會上升。但是流速愈快，通常燃料與氧化劑還沒完全消耗之前，已流出電池外，將會造成燃料的浪費。
因此在相同條件下，進行三種電池實驗。分別量測出電壓、電流密度與功率密度等數據。實驗結果顯示工作流體與薄膜呈平行之燃料電池的電流密度0.804 mA/cm2、功率密度0.263 mW/cm2為最高;而工作流體與薄膜呈垂直之燃料電池的電流密度0.525 mA/cm2、功率密度0.167 mW/cm2則最低。此外，電解液之使用將對電池之性能有顯著之影響，本研究之結果顯示，電解液不宜加入燃料，而僅能加於氧化劑中，且性能隨著濃度之增加而提升。
The major goal of this study is to compare the performances of fuel cells with and without membrane. Both the membrane fuel cells (MFC) and membraneless laminar flow based fuel cell (LFFC) are designed, fabricated, and tested under the same operation conditions.
The fuel cells are fabricated using PMMA blocks with pre-drilled flow channel and reaction chamber. For the membrane fuel cell, a Nafion membrane is employed to separate the fuel and oxidant streams. The flow channel is designed such that the flow can be either parallel to (MFC-PF) or perpendicular to (MFC-VF) membrane. The membraneless fuel cell is designed to have a Y-shaped channel. A simple platinum wire is employed as the electrode in all the fuel cells in this study. The formic acid (HCOOH) and potassium permanganate (KMnO4) solutions are used as the as the fuel and oxidant, respectively. The sulfuric acid (H2SO4) is employed as the supporting electrolyte.
The study firstly explores the concentration limits of fuel, oxidant and supporting electrolyte that can be used in the fuel cell operation. It is found that the fuel concentration is limited by the mass concentration polarization at the anode while the oxidant concentration is limited by the production of insoluble MnO2. The addition of supporting electrolyte in the oxidant is found to enhance the cell performance but is prohibited in adding into the fuel because of possible carbon monoxide production that poisoning the anode. Based on this study, it is found that the optimal concentrations for the fuel and oxidant are 2M and 0.01M, respectively. Cell performance can be enhanced in a great extent with high supporting electrolyte concentration.
Using the optimal concentrations for fuel and oxidant, the performances of three fuel cells fabricated in this study are tested and compared under the same flow rate. It is found that the membrane fuel cell with flow parallel to membrane produces the highest energy density 0.263 mW/cm2 among the three cells studied. The reason may be attributed to the reduction in concentration boundary layer thickness that increases the resultant current density. A more sophisticated design in electrode is suggested for future study in order to enhance the electrode activity.
|Appears in Collections:||機械工程學系所|
Show full item record
TAIR Related Article
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.