Performance of gold-coated titanium bipolar plates in unitized regenerative fuel cell operation

The corrosion of the carbon-based bipolar plate was studied under unitized regenerative fuel cell (URFC) operation conditions. At overpotentials higher than 2.0 V vs. normal hydrogen electrode (NHE), cell performance in the electrolyzer mode significantly decreases with time due to the increased ohmic resistance of the carbon-based bipolar plates. During fuel cell operation, the unit cell shows an ohmic resistance of approximately 0.15 Ω. After the operation in the electrolyzer mode, the ohmic resistance of the cell increases up to 1.24 Ω. The surface image of the carbon-based bipolar plate after water electrolysis reaction at 2.0 V shows a drastic corrosion at the contact area of the bipolar plate with the electrode. The corrosion of the rib in the flow-field increases the contact resistance between the electrode and the bipolar plate, which leads to the observed decrease in cell performance. A gold coating of 1 μm on the titanium bipolar plates is very effective in preventing titanium oxidation during the URFC operation. The ohmic resistance of the cells that are prepared with bare titanium and gold-deposited titanium bipolar plates is 0.40 Ω and 0.18 Ω, respectively. In fact, the gold coating serves as a barrier layer, which inhibits the formation of the passive layer on the surface of titanium-based bipolar plates. The cycling experiments in the fuel cell and in the electrolyzer mode indicate that the gold-coated titanium bipolar plates exhibit a stable performance.     

The physicochemical properties of yoghurt supplemented with microencapsulated peanut sprout extract,a possible functional ingredient

This study was designed to determine the physicochemical and sensory properties of yoghurt supplemented with powdered peanut sprout extract microcapsules (PPSEM) (3–10 μm) during storage at 4 °C for 16 days. The releasing rates of the polyphenol, resveratrol, from yoghurts were minimised at lower concentrations of PPSEM (0.25 and 0.5%, w/v). The viscosity decreased gradually with higher concentrations of PPSEM added. In the sensory test, there were significant increases in yellowness, peanut and cooked scores (P < 0.05). Based on the results, it is concluded that the low concentrations (0.25 and 0.50%, w/v) could be used to produce PPSEM‐supplemented yoghurt without significant adverse effects on the physicochemical and functional properties.     

Comparative study of flavor, texture, and sensory in cream cheese and cholesterol-removed cream cheese

This study was performed to compare flavor, texture, and sensory profiles of cream cheese and cholesterolremoved cream cheese made from whole milk and cream. The cholesterol was removed by crosslinked β-cyclodextrin and the cheeses were stored at 7°C for 4 week. To quantify the flavor compounds, the cheeses (0, 1, 2, 3, and 4 week) were extracted by solid-phase microextraction, analyzed by GC-MS and quantified by GC-flame ionization detector (FID). Tentatively identified flavor compounds were 11 acids, 2 ketones, 1 amine, 1 alcohol, 2 lactone, and 1 alkene. In texture profile analysis such as hardness, cohesiveness, adhesiveness, and sensory analysis such as appearance, flavor, taste, and texture properties were not significantly different (p>0.05) between two cheeses. On the basis of our results, it is concluded that no adverse changes was shown in the cholesterol-removed cream cheese in flavor, texture, and sensory characteristics during 4-week storage.     

The effect of magnetic and optic field in water electrolysis

Hydrogen production via water electrolysis was studied under the effect of magnetic and optical field. A diode solid state laser at blue, green and red were utilized as optical field source. Magnetic bar was employed as external magnetic field. The green laser has shown a greatest effect in hydrogen production due to its non-absorbance properties in the water. Thus its intensity of electrical field is high enough to dissociation of hydronium and hydroxide ions during orientation toward polarization of water. The potential to break the autoprotolysis and generate the auto-ionization is the mechanism of optical field to reveal the hydrogen production in water electrolysis. The magnetic field effect is more dominant to enhance the hydrogen production. The diamagnetic property of water has repelled the present of magnetic in water. Consequently the water splitting occurs due to the repulsive force induced by the external magnetic field. The magnetic distributed more homogenous in the water to involve more density of water molecule. As a result hydrogen production due to magnetic field is higher in comparison to optical field. However the combination both fields have generated superior effect whereby the hydrogen yields nine times higher in comparison to conventional water electrolysis.     

Hydrogen generation rate enhancement by in situ Fe(0) and nitroarene substrates in Fe3O4@Pd catalyzed ammonia borane hydrolysis and nitroarene reduction tandem reaction

We report the catalytic enhancement of hydrogen generation by 1) in situ Fe (0) formed and 2) nitroarenes substrates during Fe₃O₄@Pd core-shell nanoparticles catalyzed tandem reaction. The active hydrogen species are generated in Pd shell, which either combine to form H₂ gas or take part in relatively faster nitroarene reduction reaction. The rate of hydrogen generation from ammonia borane is dependent on the nitroarene substrate and is higher when 4-nitrophenol is used. This is due to the difference in ammonia borane adsorption on the surface of the catalyst. During recyclability, the H₂ generation rate of 2 wt% Pd loaded samples is higher than other compositions. Such an enhancement has been attributed to the formation of Fe (0) via γ-FeOOH mediated by Pd species, presumably through Pd(OH)₂. The electronic connection between Fe and Pd interface is thus shown to play an important role in the catalytic enhancement of the tandem reaction.     

Combined Effect of Mixed Convection and Surface Radiation Heat Transfer for Thermally Developing Flow in Vertical Channels

Combined effect of laminar flow mixed convection and surface radiation heat transfer for thermally developing airflow in a vertical channel heated from a side has been experimentally examined with different thermal and geometric parameters. The channel boundary is made of two isothermal walls and two adiabatic walls, the isothermal parallel wall is heated uniformly and the opposite cold wall temperature is maintained equal to the inlet conditions. The heated wall temperature ranged from 55 to 100°C, Reynolds number ranged from 800 to 2900 and the heat flux was varied from 250 to 870 W/m². To cover the wide range of Reynolds numbers, two aspect ratios of square and rectangular section were used. Surface radiation from the internal walls is considered through two emissivities i.e. 0.05 and 0.85, to represent weak and strong radiation effects, respectively. From the experiments, surface temperature and Nusselt number distributions of convection and radiation heat transfer are obtained for different heat flux values. Flow structure inside the channel is visualized to observe the flow pattern. The results show the combined effect of laminar flow mixed convection and surface radiation on the total heat transfer rate within the channel. The accumulating buoyancy force and airflow moves together vertically in the upward direction to give significant heat transfer enhancement in the vertical orientation of the channel.     

Performance evaluation of an acrylic mirror booster solar still for neera concentration in jaggery-making industry

A single-basin solar still was constructed from locally available materials to concentrate palm tree juice (neera) for jaggery-making application. The performance of the still was tested with and without an acrylic mirror booster on both partially cloudy and clear sunshine days. About 73% of water content from neera was evaporated within 2 days by using the mirror booster technique in clear sunshine days. Distilled water of about 7.26 l was extracted from 10 l of neera with the mirror booster condition. Wind velocity showed a considerable effect on neera juice temperature and water vapour temperature during partially cloudy conditions. The calculated efficiency of the still with the mirror booster technique was 36.53% in clear sunshine conditions. The calculated energy conservation for the neera concentration process by using the mirror booster solar still was about 16408 kJ.     

Creep behavior of nuclear grade 316LN austenitic stainless steel at 873 K and 923 K

Mechanics of Time-Dependent Materials - Creep deformation and rupture behavior of nitrogen-alloyed (0.14 wt.%) nuclear grade 316LN austenitic stainless steel were investigated for the varying...     

Analysis of machining of FRPs using FEM

An initial attempt has been made to develop a mathematical model for machining of FRPs. The anisotropic theory of plasticity has been utilized. The analysis is carried out for four different FRP materials and for four different fibre orientation angles. A total Lagrangian formulation-based transient elasto-plastic finite element analysis has been adopted.