Effect of mass recovery evaporator temperature and condenser temperature on the performance of a solar adsorption-based desalination plant

Water scarcity increases alarmingly as the population increases. Over the years, a number of salt water desalination techniques have been proposed and reached limitations. The requirement of minimum energy is very well satisfied by an adsorption system, since it can operate with low-grade energy and waste heat exhaust from most industries. The first part of this work discusses the effect of condenser and evaporator temperatures on the performance of silica-gel adsorption cycle mathematically. The second part discusses the performance variations due to mass recovery in the two-bed adsorption system mathematically. It was found that the reduction in condenser temperature and increase in the evaporator temperature both increase the fresh water productivity and cooling capacity of a plant. A desalination plant with mass recovery assistance is superior in performance than the conventional plant. Portable water productivity of 8?m³/day/ton is achieved with the condenser temperature of 15°C and the evaporator temperature of 30°C.     

Kinetics of crack healing and self-repair behaviors in a sealant glass for SOFC applications

A sealant is required for the solid oxide fuel cell (SOFC) to maintain hermeticity at high operating temperatures, keep fuel and oxidant from mixing, and avoid shorting of the cell stack. Glass and glass–ceramic materials are widely used as a sealant because their properties can be tailored to meet the stringent requirements of SOFC stack, but they are susceptible to cracking. In contrast, a promising concept of self-repairable glass for seals is pursued for making reliable seals that can self-repair cracks at the SOFC operating temperatures. This concept is studied through measuring crack-healing kinetics and independent measurement of glass viscosity for relating to the observed self-repair. The cracks on the glass surface are created using a Vickers indenter to achieve a well-defined crack geometry, and then the glass is exposed to elevated temperatures for different length of times to study the crack-healing kinetics. The crack-healing kinetics is compared with the predictions of our theoretical model and found to be in good agreement. In addition, glass viscosity is extracted from the healing kinetics and compared with the independent measurement of viscosity measured from the dilatometry and sintering data to further validate the crack-healing theoretical model. These results are presented and discussed.     

Effect of two different rubbers as secondary binders on the friction and wear characteristics of non-asbestos organic (NAO) brake friction materials

Binder provides structural integrity by holding all ingredients in the composition of a brake friction material. The modified binders have played a major role in improving the frictional performance and thermal resistance of the friction material. The present research work evaluates the influence of secondary binders (Nitrile Butadiene rubber (NBR) and Styrene Butadiene rubber (SBR)) on the tribological performance of the friction material using a full-scale inertia brake dynamometer as per JASO C406 standard. Three brake pads were developed by varying the type and composition of secondary rubber binder (5%NBR, 5%SBR and 2.5%NBR + 2.5%SBR) with rest of the ingredients kept unaltered. It was found that the quantity of SBR rubber powder present as secondary binder improved dry and wet recovery. Friction coefficient (μ) exhibited better stability during the fade with the inclusion of both the rubber powders. The friction material with the inclusion of both the NBR and SBR rubber powders exhibited overall better performance than compared to the inclusion of only one secondary binder rubber in the composition. The worn-out surface of the developed friction materials and the counter discs were characterised using FESEM.     

Sr2−XLaXMgMoO6 and Sr2−XLaXMgNbO6 for Use as Sulfur‐Tolerant Anodes Without a Buffer Layer

The objective of this effort is to synthesize and characterize a series of lanthanum‐(La) doped Sr₂MgMoO₆ (SMMO) and La‐doped Sr₂MgNbO₆ (SMNO) anode materials which can be used in combination with lanthanum‐containing electrolytes to mitigate the effects of lanthanum poisoning in solid oxide fuel cells (SOFCs). Currently, an La_0.4Ce_0.6O_1.8 (LDC) buffer layer is used with many perovskite‐based anode materials to prevent La diffusion into the anode from the La_0.8Sr_0.2Ga_0.8Mg_0.2O_2.8 (LSGM) electrolyte which can create a resistive La species that impedes electrochemical performance. The LDC buffer layer, with diminished electronic conductivity, adds an extra level of complexity in the SOFC manufacturing process. Further, this extraneous layer presents an added experimental challenge when assessing anode material performance. Overall electrochemical performance could be improved if the resistive buffer layer could be removed, thereby allowing the anode material to have direct contact with the electrolyte. To accomplish this, a new class of anode materials was synthesized with the goal of balancing “La” chemical potential between these neighboring materials. La‐doped SMMO and SMNO were prepared and studied. It was hypothesized that by incorporating La into the anode, the gradient of chemical activity between the anode and electrolyte would decrease, which would prevent La diffusion. These anode materials were synthesized via a sol–gel methodology and characterized with X‐ray diffraction to assess phase purity. The conductivity of the materials was analyzed in the presence of both H₂ and 100 ppm H₂S/H₂ to determine the stability and performance of these materials during device operation. The stability experiments demonstrated that 40% La‐doped SMNO is stable in all pertinent environments while not reacting with the LSGM electrolyte.     

Synthesis of nanostructured copper hexacyanidoferrate and its application in voltammeteric detection of salbutamol

Nanostructured copper hexacyanidoferrate has been synthesized and characterized using elemental analysis, atomic absorption spectroscopy, thermal and infrared spectral studies. The transmission electron microscopic studies of the synthesized material showed that it consisted of irregular oval and rod shaped particles with a size range 70–100 nm. Nanostructured copper hexacyanidoferrate modified glassy carbon electrode was characterized by cyclic voltammetery and nanostructured copper hexacyanidoferrate–carbon nanotube composite material modified glassy carbon electrode has been used for electrocatalytic oxidation of salbutamol. The electrode modified with composite material was found to reduce the peak potential of oxidation of salbutamol by nearly 90 mV.     

Analytical study of nuclear-coupled density-wave instability in a natural circulation pressure tube type boiling water reactor

An analytical model has been developed to study the nuclear-coupled density-wave instability in the Indian advanced heavy water reactor (AHWR) which is a natural circulation pressure tube type boiling water reactor. The model considers a point kinetics model for the neutron dynamics and a lumped parameter model for the fuel thermal dynamics along with the conservation equations of mass, momentum and energy and equation of state for the coolant. In addition, to study the effect of neutron interactions between different parts of the core, the model considers a coupled multipoint kinetics equation in place of simple point kinetics equation. Linear stability theory was applied to reveal the instability of in-phase and out-of-phase modes in the boiling channels of the AHWR. The results indicate that the stability behavior of the reactor is greatly influenced by the void reactivity coefficient, fuel time constant, radial power distribution and channel inlet orificing. The delayed neutrons were found to have a strong influence on the Type I and Type II instabilities observed at low and high channel powers, respectively. Also, it was found that the coupled multipoint kinetics model and the modal point kinetics model predict the same threshold power for out-of-phase instability if the coupling coefficient in the former model is half the eigen value separation between the fundamental and the first harmonic mode in the latter model. Decay ratio maps were predicted considering various operating parameters of the reactor, which are useful for its design.     

Phase behaviour modelling of Athabasca bitumen for in situ combustion applications

Phase behaviour modelling of reservoir fluid is a fundamental step for reservoir simulation. Furthermore, as the complexity of the recovery process increases, the fluid model plays a more important role in the reliability of the simulation outputs. Although the in situ combustion enhanced oil recovery method (ISC) is one of the most complex recovery techniques available in the petroleum engineering literature, for most of the simulation jobs related to this elaborate process only simple and rudimentary fluid characterization layouts are considered. In this work, the principal fluid properties of Athabasca bitumen with regard to the ISC process are recognized, extracted from the literature, validated for consistency, and used for the development of an inclusive and accurate fluid model. Then the fluid model is fully developed while considering the ISC reaction kinetics so that the model has both accuracy, indispensable for phase behaviour modelling, and consistency, essential for the reactions definitions.     

Biocomposite proton‐exchange membrane electrolytes for direct methanol fuel cells

Poly(vinyl alcohol) (PVA)‐amino acid (AA) biocomposite membranes are prepared by blending PVA with AAs such as glycine, lysine (LY), and phenyl alanine followed by in situ crosslinking with citric acid (CA) and explored as a new class of biocomposite membrane electrolytes for direct methanol fuel cells (DMFCs). CA crosslinks with PVA through esterification offers adequate chemical, thermal, and morphological stability thereby produces methanol‐obstructing close‐packed polymeric network. These biocomposite membranes are characterized in terms of mechanical, thermal, sorption, and proton‐conducting properties. Hydrophilic nature of AA zwitterions significantly facilitates proton conduction and CA crosslinking mitigates methanol crossover through establishing appropriate balance between hydrophilic/hydrophobic domains. The rational design of membrane microstructure with proper arrangement of hydrophobic/hydrophilic domains is a key to enhance electrochemical selectivity of PVA‐AA/CA biocomposite membranes. Biocomposite membrane comprising LY exhibits nearly threefold higher electrochemical selectivity in relation to PVA/CA blend membrane. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43514.     

Solid Yttria-Stabilized Zirconia Films by Pulsed Chemical Vapor Deposition from Metal-organic Precursors

A pulsed chemical vapor deposition from metal-organic precursors (MOCVD) system was used to produce solid zirconia, and yttria-stabilized zirconia (YSZ) films. A total of six candidate metal-organic precursors for zirconia and three for yttria were investigated. Three precursor solutions for YSZ proved suitable for pulsed-MOCVD processing. Layers were deposited on metal, alumina, and porous nickel cermet substrates. Under optimal deposition conditions, precursor conversion efficiency of 90% was achieved using a solution of 3.74 vol% zirconium 2-methyl-2-butoxide + 0.42% yttium methoxyethoxide in toluene. The film growth rate was 7.5 μm·h⁻¹ at 525°C deposition temperature. Two alkoxide precursors produced YSZ layers with material costs under $0.50/(μm·cm²).