Agricultural waste ashes are used as resource materials to synthesize new glass and glass-ceramics. The as-prepared materials are characterized using various techniques for their structural and dielectric properties to check their... more
Agricultural waste ashes are used as resource materials to synthesize new glass and glass-ceramics. The as-prepared materials are characterized using various techniques for their structural and dielectric properties to check their suitability in microelectronic applications. Sugarcane leaves ash exhibits higher content of alkali metal oxides than rice husk ash, which reduces the melting point of the components due to eutectic reactions. The addition of sugarcane leaves ash in rice husk ash promotes the glass formation. Additionally, it prevents the cristobalite phase formation. These materials are inherently porous, which is responsible for low dielectric permittivity i.e. 9 to 40. The presence of less ordered augite phase enhances the dielectric permittivity as compared to cristobalite and tridymite phases. The present glass-ceramics exhibit lower losses than similar materials synthesized using conventional minerals. The dielectric permittivity is independent to a wide range of tem...
Fuel cell is the most promising candidate for future energy system as it is energy efficient and utilizes a renewable fuel. However, there still is need for upgradation and a fully paired computational fluid dynamics (CFD) approach (based... more
Fuel cell is the most promising candidate for future energy system as it is energy efficient and utilizes a renewable fuel. However, there still is need for upgradation and a fully paired computational fluid dynamics (CFD) approach (based on the finite volume method). A 3D simulation of planar Solid Oxide Fuel Cell (SOFC) having internal reforming has been carried out by examining the geometry of a single cell which comprises of a fuel channel, air channel, cathode, anode, and electrolyte layers. Cell parameters such as temperature, current density, concentration of fuel species, electro chemical processes and voltage are analyzed for both co-flow and counter-flow configurations. The obtained finite volume results were validated with experimental and numerical results showing good agreement within acceptable limits. An increase in inlet temperature resulted in significant increase in cell operating voltage as well as cell power density and the cell efficiency increases by 12 e13%. It is also observed that the co-flow configuration showed more uniform current density and temperature distributions as well as smaller temperature gradients. Therefore, co-flow configuration is superior as it experiences low thermal stresses in PEN structure and enhanced cell life.
The CeO2-based electrolyte low temperature SOFCs require special electrodes with a higher performance and compatibility. The performance of the CeO2-based composite anodes depends on microstructural features such as particle size, tripe... more
The CeO2-based electrolyte low temperature SOFCs require special electrodes with a higher performance and compatibility. The performance of the CeO2-based composite anodes depends on microstructural features such as particle size, tripe phase boundaries (TPB), surface area, and percolation. Some of the primary parameter can be manipulated during the materials synthesis. In this work the compound NiO–Ce0.9Gd0.1O1.95 (NiO–CGO), used as anode in SOFC, was synthesized by two different processes. Both of them are based on the polymeric precursor method. Characterized by simultaneous thermogravimetry-differential thermal analysis, X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy and dilatometry. The refinement of the XRD data indicated that the composite sample synthesized by the process called “one step synthesis” produced smaller crystallite size in comparison to the sample attained by the two steps process. Simple preliminary performance tests were done with single cells in which such I–V curves indicated that the cell with one step anode had better performance. “One step synthesis” product, in situ nanocomposite, presented similar fine grained particle sizes for both phases Ni and CGO, which would be beneficial to the electrochemical activity, also indicated by first performance tests.
Agricultural waste ashes are used as resource materials to synthesize new glass and glass-ceramics. The as-prepared materials are characterized using various techniques for their structural and dielectric properties to check their... more
Agricultural waste ashes are used as resource materials to synthesize new glass and glass-ceramics. The as-prepared materials are characterized using various techniques for their structural and dielectric properties to check their suitability in microelectronic applications. Sugarcane leaves ash exhibits higher content of alkali metal oxides than rice husk ash, which reduces the melting point of the components due to eutectic reactions. The addition of sugarcane leaves ash in rice husk ash promotes the glass formation. Additionally, it prevents the cristobalite phase formation. These materials are inherently porous, which is responsible for low dielectric permittivity i.e. 9 to 40. The presence of less ordered augite phase enhances the dielectric permittivity as compared to cristobalite and tridymite phases. The present glass-ceramics exhibit lower losses than similar materials synthesized using conventional minerals. The dielectric permittivity is independent to a wide range of temperature and frequency. The glass-ceramics developed with adequately devitrified phases can be used in microelectronic devices and other dielectric applications.
Fabrication of a fiber anode with a mixture of the Gd 2 O 3 and SrO co-doped ceria fibers and the Ni nano-catalyzer by using electrospinning and impregnated process were carried out for application in an intermediate... more
Fabrication of a fiber anode with a mixture of the Gd 2 O 3 and SrO co-doped ceria fibers and the Ni nano-catalyzer by using electrospinning and impregnated process were carried out for application in an intermediate temperature fuel cell (ITFC). Experimental results demonstrate that a uniform co-doped ceria fiber of 100 nm diameter could be spun at the concentration of PVP approximately 11.32 wt.% and electric field of 20 kV. The anodic films were prepared via a nickel wet dipping process and sintered at different temperatures. The micrograph of the anode sintered at 1200 o C for1hr has a well defined microstructure in terms of electrolyte area covered with nickel and the triple phase boundary (TPB) between electrolyte, electrode and gas phase. Fiber anode exhibits low polarization resistance and high exchange current density due to formation of the reticular nano-fiber structure. Accordingly, using a new concept of combination of the nano-ceramic fiber and the Ni nano-particle for increasing the catalytic properties of anode is successfully proved, it is found that nano-fiber substituting to powder in anode could decrease the processing temperature of cell and maintain the porous structure of anode to increase the amount of TPB and restrain formation of agglomerates of nickel particles.
A unique nanostructured NiO-yttria-stabilized zirconia (YSZ) composite is synthesized in-situ via a water-in-oil microemulsion technique for the solid oxide fuel cell (SOFC) anode. Thermogravimetric analysis and X-ray diffraction confirm... more
A unique nanostructured NiO-yttria-stabilized zirconia (YSZ) composite is synthesized in-situ via a water-in-oil microemulsion technique for the solid oxide fuel cell (SOFC) anode. Thermogravimetric analysis and X-ray diffraction confirm that as-synthesized powders are crystallized in-situ at ~500 C as the distinct NiO and YSZ phases without any impurities. Moreover, transmission electron microscopy analysis reveals that the as-synthesized primary particles via microemulsion are ~40 nm in size and have a characteristic structure in which NiO and YSZ nanograins are heterogeneously distributed. The elec-trochemical activity of the nanostructured NiO-YSZ composite is evaluated using an YSZ supported cell with a La 0.8 Sr 0.2 MnO 3-d-YSZ (50:50 wt.%) cathode. The maximum power density of the SOFC employing the microemulsion-mediated NiO-YSZ anode is 2.2 times greater than that of the SOFC with the conventionally ball-milled nano-sized NiO-YSZ anode. The higher performance with our nanocomposite NiO-YSZ anode is primarily attributed to its heterogeneous nanograin structure, thus leading to a significant increase in triple phase boundary densities.
