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Cell Voltage (cell + voltage)
Selected AbstractsVariation of Cell Voltage with Reaction Time in Electrochemical Synthesis Process of Sodium DichromateCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 4 2006C. W. Li Abstract To address the problems existing in the traditional production technique of sodium dichromate, a new green technology of producing sodium dichromate with an electrochemical synthesis method was studied. Using a self-made electrosynthesis reactor of pure titanium and stainless steel, with a multiple-unit metal oxides combination anode, a cathode of stainless steel, and a reinforcing combination cation exchange membrane with perfluorosulfonic and perfluorocarboxylic polymers, experiments were carried out on the direct electrochemical synthesis of sodium dichromate from sodium chromate. From the experimental results and electrochemical reaction principles, it was shown that the electrochemical synthesis reaction process of sodium dichromate may be quantitatively determined from the variation of the cell voltage measured macroscopically with reaction time. Cell voltages were experimentally measured at different initial sodium chromate concentrations in the anolyte, and the dependence of the cell voltage on reaction time was discussed. The mathematical model of the variation of cell voltage with reaction time and the change rate equation of cell voltage were established, and satisfactorily formulated the change law of cell voltage in the electrochemical synthesis process of sodium dichromate. [source] Study on Glucose Biofuel Cells Using an Electrochemical Noise DeviceELECTROANALYSIS, Issue 14 2008Yueming Tan Abstract An electrochemical noise (ECN) device was utilized for the first time to study and characterize a glucose/O2 membraneless biofuel cell (BFC) and a monopolar glucose BFC. In the glucose/O2 membraneless BFC, ferrocene (Fc) and glucose oxidase (GOD) were immobilized on a multiwalled carbon nanotubes (MWCNTs)/Au electrode with a gelatin film at the anode; and laccase (Lac) and an electron mediator, 2,2,-azinobis (3-ethylbenzothiazoline-6-sulfonate) diammonium salt (ABTS), were immobilized on a MWCNTs/Au electrode with polypyrrole at the cathode. This BFC was performed in a stirred acetate buffer solution (pH,5.0) containing 40,mmol/L glucose in air, with a maximum power density of 8,,W/cm2, an open-circuit cell voltage of 0.29,V, and a short-circuit current density of 85,,A/cm2, respectively. The cell current at the load of 100,k, retained 78.9% of the initial value after continuous discharging for 15,h in a stirred acetate buffer solution (pH,5.0) containing 40,mmol/L glucose in air. The performance decrease of the BFC resulted mainly from the leakage of the ABTS mediator immobilized at the cathode, as revealed by the two-channel quartz crystal microbalance technique. In addition, a monopolar glucose BFC was performed with the same anode as that in the glucose/O2 membraneless BFC in a stirred phosphate buffer solution (pH,7.0) containing 40,mmol/L glucose, and a carbon cathode in Nafion-membrane-isolated acidic KMnO4, with a maximum power density of 115,,W/cm2, an open-circuit cell voltage of 1.24,V, and a short-circuit current density of 202,,A/cm2, respectively, which are superior to those of the glucose/O2 membraneless BFC. A modification of the anode with MWCNTs for the monopolar glucose BFC increased the maximum power density by a factor of 1.8. The ECN device is highly recommended as a convenient, real-time and sensitive technique for BFC studies. [source] Experiment and simulation investigations for effects of flow channel patterns on the PEMFC performanceINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 1 2008Yuh-Ming Ferng Abstract Experiments and simulations are presented in this paper to investigate the effects of flow channel patterns on the performance of proton exchange membrane fuel cell (PEMFC). The experiments are conducted in the Fuel Cell Center of Yuan Ze University and the simulations are performed by way of a three-dimensional full-cell computational fluid dynamics model. The flow channel patterns adopted in this study include the parallel and serpentine flow channels with the single path of uniform depth and four paths of step-wise depth, respectively. Experimental measurements show that the performance (i.e. cell voltage) of PEMFC with the serpentine flow channel is superior to that with the parallel flow channel, which is precisely captured by the present simulation model. For the parallel flow channel, different depth patterns of flow channel have a strong influence on the PEMFC performance. However, this effect is insignificant for the serpentine flow channel. In addition, the calculated results obtained by the present model show satisfactory agreement with the experimental data for the PEMFC performance under different flow channel patterns. These validations reveal that this simulation model can supplement the useful and localized information for the PEMFC with confidence, which cannot be obtained from the experimental data. Copyright © 2007 John Wiley & Sons, Ltd. [source] A semi-empirical cell voltage model for polymer electrolyte/methanol systems: Applicability of the group contribution methodJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008Ji Yun Seong Abstract A new group contribution model is established to describe the cell voltage of a direct methanol fuel cell as a function of the current density. The model equation is validated with experimental data over a wide range of methanol concentrations and temperatures. The proposed model focuses on very unfavorable conditions for cell operation, that is, low methanol solution concentrations and relatively low cell temperatures. The proposed group contribution method includes a methanol crossover effect that plays a major role in determining the cell voltage of a direct methanol fuel cell. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Polybenzimidazoles for High Temperature Fuel Cell ApplicationsMACROMOLECULAR RAPID COMMUNICATIONS, Issue 15 2004Hyoung-Juhn Kim Abstract Summary: Fuel cells were designed for high temperature operations. Poly[2,2,-(m -phenylene)-5,5,-bibenzimidazole] (PBI) was synthesized in a solution of P2O5, CH3SO3H, and CF3SO3H. The PBI was dissolved in a mixture of CF3CO2H and H3PO4 and the solution was used for the preparation of Pt catalyst slurry for membrane electrode assembly. The single cell showed a current density of 280 mA,·,cm,2 at a cell voltage of 0.5 V with feeds of H2 and O2 at 160,°C and without external humidification. [source] Microstructure of nanopores in AAO templates favoring the growth of nickel nanowires by electrodepositionPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 12 2007Jong-Hyun Jeong Abstract Morphology of periodical nanoscale pores in AAO templates has been studied in relation with anodizing process, focusing on the growth of nickel nanowires by electrochemical deposition. The AAO templates were prepared by a two-step anodization process. The high purity aluminum plates were anodized in oxalic acid aqueous solution with variation of cell voltage. The pore size and interpore distance both increase with the applied potential. During the post treatment of barrier thinning, small-size pores with split-up structure at the tips are observed due to current-limited anodizing process (decreasing cell potential). The rectifying properties of the barrier layer allow the pores to be filled by nickel by AC electrodeposition. The nickel nanowires array shows the ferromagnetic properties with a preferred magnetic orientation along the wire axis. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Modeling of a process for removal of metal ions by electromigration and electrodepositionTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2002Kanchan Mondal Abstract A mathematical model for the removal of impurities of the metal ions of Fe, Ni, and Cu from hard chromium plating solution by electromigration and subsequent electrodeposition has been developed and presented. Experimental data for the metal removal at 45°C and constant cell voltage using o-phosphoric acid as the catholyte are presented. Up to 36% iron and 29% nickel removal is obtained over about 25 h. The copper removal rate is observed to be approximately four times greater than the rate of nickel removal. The experimental data were found to closely match results predicted from the model developed. The inherent model parameters such as mobility, diffusivity, mass transfer coefficient and metal deposition rate constants were estimated. The calculated values of these parameters are found to be in good agreement with the published data. On présente un modèle mathématique pour le retrait des impuretés des ions métalliques de Fe, Ni et Cu d'une solution de revêtement de chromage dur par électromigration et électrodéposition subséquente. Des données expérimentales pour le retrait métallique à 45°C et le voltage d'éléments constants à l'aide de l'acide o-phosphorique comme catholyte sont présentées. Un retrait de 36% pour le fer et de 29% pour le nickel est obtenu sur une période de 25 h approx. On observe que le taux de retrait du cuivre est approximativement quatre fois plus grand que le taux de retrait du nickel. Les données expérimentales concordent étroitement avec les résultats prédits à partir du modèle mis au point. Les paramètres propres du modèle comme la mobilité, la diffusivité, le coefficient de transfert de matière et les constantes de taux de déposition des métaux ont été estimés. Les valeurs calculées de ces paramètres montrent un bon accord avec les données publiées. [source] Photosynthetic microbial fuel cells with positive light responseBIOTECHNOLOGY & BIOENGINEERING, Issue 5 2009Yongjin Zou Abstract The current study introduces an aerobic single-chamber photosynthetic microbial fuel cell (PMFC). Evaluation of PMFC performance using naturally growing fresh-water photosynthetic biofilm revealed a weak positive light response, that is, an increase in cell voltage upon illumination. When the PMFC anodes were coated with electrically conductive polymers, the rate of voltage increased and the amplitude of the light response improved significantly. The rapid immediate positive response to light was consistent with a mechanism postulating that the photosynthetic electron-transfer chain is the source of the electrons harvested on the anode surface. This mechanism is fundamentally different from the one exploited in previously designed anaerobic microbial fuel cells (MFCs), sediment MFCs, or anaerobic PMFCs, where the electrons are derived from the respiratory electron-transfer chain. The power densities produced in PMFCs were substantially lower than those that are currently reported for conventional MFC (0.95,mW/m2 for polyaniline-coated and 1.3,mW/m2 for polypyrrole-coated anodes). However, the PMFC did not depend on an organic substrate as an energy source and was powered only by light energy. Its operation was CO2 -neutral and did not require buffers or exogenous electron transfer shuttles. Biotechnol. Bioeng. 2009; 104: 939,946. © 2009 Wiley Periodicals, Inc. [source] Variation of Cell Voltage with Reaction Time in Electrochemical Synthesis Process of Sodium DichromateCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 4 2006C. W. Li Abstract To address the problems existing in the traditional production technique of sodium dichromate, a new green technology of producing sodium dichromate with an electrochemical synthesis method was studied. Using a self-made electrosynthesis reactor of pure titanium and stainless steel, with a multiple-unit metal oxides combination anode, a cathode of stainless steel, and a reinforcing combination cation exchange membrane with perfluorosulfonic and perfluorocarboxylic polymers, experiments were carried out on the direct electrochemical synthesis of sodium dichromate from sodium chromate. From the experimental results and electrochemical reaction principles, it was shown that the electrochemical synthesis reaction process of sodium dichromate may be quantitatively determined from the variation of the cell voltage measured macroscopically with reaction time. Cell voltages were experimentally measured at different initial sodium chromate concentrations in the anolyte, and the dependence of the cell voltage on reaction time was discussed. The mathematical model of the variation of cell voltage with reaction time and the change rate equation of cell voltage were established, and satisfactorily formulated the change law of cell voltage in the electrochemical synthesis process of sodium dichromate. [source] | |||||||||||||