Authors: Yu Kui Wang, X. Li, H. Chen, Zhen Long Wang, De Bin Shan
Abstract: In this paper micro-electrochemical turning for fabricating microelectrode is presented. A stainless steel film with 50 μm thickness as turning tool is the cathode and a rotary tungsten rod for the proposed microelectrode fabrication is the anode. By applying ultra short pulses in micro seconds, dissolution of the anode can be restricted to the small region very close to the cathode. Due to rotation of the anode and movement of the cathode along the rotary axis direction, the anode uniformity corrosion was improved and its rotating concentricity was ensured simultaneously. A micro-electrode with a high aspect ration, namely 20 μm in diameter and 2500 μm in length has been fabricated in the low concentration electrolyte, 4%NaOH.
269
Authors: Shi Gang Yu, Hui He, You Sheng Xu
Abstract: A composite three-dimensional mathematical model of proton exchange membrane fuel cell is proposed, the corresponding finite element method and numerical simulation are given as well, where fluid flow, proton transport, and electrochemical reaction are addressed. Some factors that probably affect the performance of the cell are analyzed by using the model. The computational results show that the reactant concentration decreases along the flow direction, the water concentration increases in the cathode side of membrane, membrane resistance decreases, conductivity increases and proton concentration increases. The fuel cell performance is better when the porosity increases, as well as the operating pressure.
376
Authors: Cheng Guang Zhang, Fei Hu Zhang, Yong Zhang
Abstract: The theory of electrochemical jet machining was introduced, and effect of different parameters on anodic electric field intensity is finite element analyzed by ANSYS software. The Simulation results show that, the electric field shares the same distribution under different electrolysis voltage, which generally contains three parts, uniform distribution area, gradually weakened area, scattered area. In the uniform distribution area, electric field shows comparative uniformity. The anode electric field generated by different jet distance is also obvious distribution areas, the electric field intensity shows decreasing trend. Electric field intensity is found to have a close relationship with electro jet nozzle diameter, in which a faster jet velocity would bring more concentrated distribution of the electric field as well as a smaller size of electric field.
2046
Authors: Biao Yu, Han Zhao
Abstract: To investigate the influence geometric parameters on the performance of direct methanol fuel cell (DMFC), experimental study and computational fluid dynamics (CFD) based on modeling are conducted in the research. Three types of geometric configurations with serpentine flow channels and similar open areas with different widths are fabricated to be tested. The experimental results show that the geometric configuration with narrower width has better performance. To explain and understand such phenomena, a CFD based modeling is introduced. The model results show that the geometric configuration with narrower width has higher pressure inside the diffusion layers and more delivery of fuel and oxygen to the catalyst layers. Since high pressure and high fuel and oxygen delivery can improve the DMFC performance, the CFD model provides very good explanations to the experimental phenomena. The research results could provide some very useful guidelines for the design and optimization of DMFC system.
754
Abstract: Gear’s pulse electrochemical finishing (PECF) technology by shaped electrodes based on the numeral control technology, which controls gear dividing device and feed movement, is put forwards. Based on numerical simulation, electrochemical reaction region is dispersed. According to gear tooth profile and negative electrode surface equations, boundary conditions are inferred. The numerical simulation of the electric potential distribution in the calculation region has been shown. Under the optimized parameters, a mirror-like surface of gear teeth could be gained by PECF. The results show PECF can fulfill the advantages in the finishing some special gears with hard teeth.
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