SUMMARY In this paper, a new design for the flow channels is presented, and a parametric study of the proton exchange membrane (PEM) fuel cell is conducted in order to investigate the effect of the new flow channels, as well as different operating parameters, on the efficiency and energy output of the cell. Design parameters are selected based on studies presented in the literature to build a physical and practical model. With the new design of the flow channels, it is noticed that the cell efficiency increases from 33.8% to 47.7% if the temperature of the cell is increased. The power output of the cell increases from 2.6 to 282.5 W when the cell temperature and the current density are increased. Moreover, decrease in the efficiency of the cell ranges from 45.5% to 28.4% with the increase in the current density and membrane thickness. Based on the analytical model, design parameters were selected to manufacture a fuel cell that has a power output of 175 W and an efficiency of 35% running at 353 K and 3 bar, with an effective membrane area of 450 cm2. Experiments are conducted to investigate the effect of newly designed flow channels on pressure distribution. It is found that when hydrogen is supplied from both inlets, pressure across the channels become symmetric and, therefore increasing the power output. This study reveals that, with the proper choice of design parameters, a PEM fuel cell is an attractive economical, efficient, and environmental solution when compared with conventional systems of power generation such as gas turbines. Copyright © 2011 John Wiley & Sons, Ltd.
Ion exchange membranes, specifically resin technology, lie at the heart of electrolytically conductive systems used in the treatment of wastewater. This chapter deals with ion exchange deionization and the effect of resin amount as well as the concentration of acid and base on the product conductivity. The strong acidic cation polymeric exchanger resin is commercially called MERCK 104765 cation exchanger IV with capacity greater than 3.2 mmol/ml, while the strong basic anion polymeric exchanger resin is commercially called MERCK 104767 anion exchanger III with capacities greater than 1.0 mmol/ml. Water conductivity, as an indicator of regeneration efficiency, was monitored over time at the different conditions and scenario. In general, it was observed that the conductivity decreases with time until one point is reached and then starts to increase as a result of resin saturation. It was also noticed that the lowest conductivity is achieved when using 1-vol% NaOH and 5-vol% HCl in the cathodic and anodic resin tubes, respectively, and that water conductivity increases with the increase in the amount of water being used. The amount of resin significantly impacts the deionization efficiency; more ions are removed as the amount of resin increases.
This study investigated the suitability and performance of a pilot-scale membrane bioreactor (MBR). Huber vacuum rotation membrane (VRM 20/36) bioreactor was installed at the Sharjah sewage treatment plant (STP) in the United Arab Emirate for 12 months. The submerged membranes were flat sheets with a pore size of 0.038 lm. The VRM bioreactor provided a final effluent of very high quality. The average reduction on parameters such as COD was from 620 to 3 mg/l, BOD from 239 to 3 mg/l, Ammonia from 37 to 2 mg/l, turbidity from 225NTU to less than 3NTU, and total suspended solids from 304 mg/l to virtually no suspended solids. The rotating mechanism of the membrane panels permitted the entire membrane surface to receive the same intensive degree of air scouring, which lead to a longer duration. The MBR process holds a promising future because of its smaller footprints in contrast to conventional systems, superior effluent quality, and high loading rate capacity.
Process simulation using ASPEN Plus is carried out to model a two-stage alkali catalyzed transesterification reaction for converting micro algal oil to biodiesel. A 6:1 methanol to algal oil feed ratio is assumed using NaOH as a catalyst at 60 o C reaction temperature, which results in almost 99 % biodiesel yield for the trans-esterification reaction. Product quality is assessed and compared with market bio-diesel and petro-diesel. It is shown that this project is technically feasible, which makes algal oil a much more competitive substitute to food-based plant oils.
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