Anodic potential on dual-chambered microbial fuel cell with sulphate reducing bacteria biofilm

Dual chamber microbial fuel cell reactors were inoculated with a mixed culture of sulfate-reducing bacteria with anode potential being the controlling parameter. A negative poised anode potential enhanced the performance of this fuel cell while a positive poised anode potential had adverse effects on cell performance. Negative anodic potential affects the biofilm characteristics, as evidenced by electrochemical analysis. Microbial community was changed accordingly.     

电子汽车衡常见故障与预防

本文主要以举例的方式介绍电子汽车衡常见故障及排除方法,再从实际工作出发如何去预防故障的发生。     

Investigating the role of a Schiff-base ligand in the characteristics of TiO2 nano-particles: Particle size,optical properties,and photo-voltaic performance of dye-sensitised solar cells

A Schiff base ligand was employed to synthesise TiO₂ nano-particles by a two-step sol–gel method. The effect of the ligand on purity, particle size, optical properties and photo-voltaic performance of dye-sensitised solar cells was investigated. Various concentrations of the ligand were applied and each sample was characterised. Changing the ligand content had an effective role on the optical and photo-voltaic properties of the final product. The obtained products were characterised through powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectra, energy-dispersive X-ray spectrometry and ultraviolet–visible spectroscopy.     

Development of open-cathode polymer electrolyte fuel cells using printed circuit board flow-field plates: Flow geometry characterisation

Open-cathode air-breathing fuel cells have the advantage of reduced system complexity and simplified operation, as oxygen is taken directly from ambient air without the need for blowers/compressors. In this study, printed circuit boards (PCBs) are used as flow-field plates. The use of PCBs offers the potential for significant cost reduction due to their well-established manufacturing processing and low materials cost. This study investigates the effect of varying the cathode geometry (parallel and circular) and opening ratios (43%, 53% and 63%) on fuel cell performance using polarisation curves, electrochemical impedance spectroscopy (EIS) and thermal imaging. The results obtained indicate that circular openings afford lower Ohmic resistance than parallel flow-field designs, which helps improve contact between the gas diffusion layer and flow-field plate. However, flow-field plates with circular openings suffer from greater mass transport limitation effects. Likewise, greater opening ratios offer better mass transport but increased Ohmic resistance as a result of the reduced area of lands/ribs. The thermal imaging results reveal lower temperature in the middle of the fuel cell due to “bowing” of the printed circuit board flow field plates which reduces the local current density. A trade-off between these factors results in a design with a maximum area specific power density of 250 mW cm⁻².     

Investigation of mass transport and cell performance on μDMFC with different anode flow fields

The study systematically analyzes the performance of micro direct methanol fuel cell (μDMFC) with different flow fields. A two‐phase three‐dimensional model is developed to evaluate the mass transport accurately. The transport of methanol and air, the pressure distribution, the anode saturation, and the methanol crossover are numerically observed, the under‐rib convection is also investigated numerically. The flow fields with an active area of 0.64 cm² are fabricated on silicon wafers by micro electromechanical system technology. Performance of μDMFCs with different flow fields is sorted as: double‐serpentine flow field (DSFF) > single‐serpentine flow field (SSFF) > triple‐serpentine flow field (TSFF), and the dynamic test results indicate the cell with DSFF takes the shortest time to reach a stable power output when compared with other cells. Copyright © 2013 John Wiley & Sons, Ltd.     

Hydrogen permeation across super‐thin membrane and the burning limitation in low‐temperature proton exchange membrane fuel cell

Hydrogen permeation across the membrane is unavoidable in proton exchange membrane fuel cells, especially for super‐thin membranes, which lowers the open‐circuit voltage and could even be a safety concern. In this paper, hydrogen permeation across two membranes (25‐um‐thick Nafion^® 211 and 18‐um‐thick reinforced composite membrane) are evaluated at various temperatures, relative humidity (RH), and gas pressure differences between the anode and cathode. The results indicate that the hydrogen permeation rate in both membranes increases almost exponentially with temperature and linearly with pressure differences. Compared with RH, the effects of temperature and pressure differences are more crucial to hydrogen permeability. However, the effect of RH on the hydrogen permeation is quite complicated. The permeability exhibits a minimum value at intermediate RH (approximately 40% RH) for both applied membranes. The permeability of Nafion^® 211 appears more sensitive to RH than that of reinforced composite membrane at elevated temperature. Copyright © 2013 John Wiley & Sons, Ltd.