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Liquid-liquid two-phase flows are central to solvent extraction processes. In a columnar solvent extraction contactor, the turn-down ratio can be increased by imposing oscillatory flow over steady ...

Uranium(VI) ions transport through hollow fibre supported liquid membrane (HFSLM) using TBP (tri-n-butyl phosphate) in n-dodecane as the extractant and 0.01 M HNO3 as strippant is modelled by using...

Computational Fluid Dynamics (CFD) is used to predict continuous phase axial dispersion coefficient for liquid-liquid two-phase flow in a pulsed-sieve plate column (PSPC). The CFD model is based on...

Computational fluid dynamics – population balance (CFD-PB) simulations are performed to predict Sauter mean drop diameter and dispersed phase holdup for liquid–liquid two-phase flow in a pulsed dis...

A two-dimensional axisymmetric computational fluid dynamics (CFD) model is presented to simulate uranium extraction from nitric acid medium using tri-n-butyl phosphate in n-dodecane in a hollow-fib...

The phenomenon of drop formation at a single plain hole and a single nozzle hole in a plate submerged in a quiescent continuous phase is studied by carrying out numerical simulations. Phase...

This study reports a detailed comparison of dispersed-phase holdup and onset of different operating regimes in PSPC (pulsed sieve-plate column) and PDDC (pulsed disc-and-doughnut column) for 3 N ni...

CFD simulations of pulsed disc and doughnut columns are performed to understand the effects of operating and geometric parameters on axial dispersion and pressure drop in single-phase flow. CFD sim...

Computational Fluid Dynamics (CFD) simulations of two-phase flow to predict dispersed phase hold up in a pulsed sieve-plate column have been performed and validated with reported experimental data. Suitability of different drag models for predicting dispersed phase hold up has been evaluated. Drag models applicable for concentrated dispersions are found to be better than the drag models applicable for lean dispersions. Kumar–Hartland drag model is found to be the best among the reported drag models with average error between predicted and experimental hold up being about 15%. Parameters of the Kumar–Hartland drag model are modified to further reduce the error to about 10%.

Solvent extraction experiments are carried out in a t-junction serpentine microchannel and a split-and-recombine microchannel with TBP-nitric acid system. Stripping experiments have been carried out in the t-junction serpentine microchannel. The effects of residence time and O/A ratio on overall volumetric mass-transfer coefficients are discussed. Flow patterns in microchannels are observed to have more insight into experimental trends. For the same average velocity, the split-and-recombine microchannel is found to give higher overall volumetric mass-transfer coefficient. Overall volumetric mass-transfer coefficients observed for the two microchannels are compared with overall volumetric mass-transfer coefficients reported for conventional extractors.

In this study, the commonly used well known empirical relationships between stress and strain are analysed with respect to experimental stress – strain curves obtained for 316L austenitic stainless steel. It was observed that the Ludwick and Ludwigson equation fits the experimental stress – strain data more closely at lower strains and the Voce relation at higher strains for different grain size samples and at various testing temperatures. Overall, the Voce relation fits the experimental stress – strain curve better than other empirical relations. The various parameters of the different empirical relations are analysed with respect to grain size and temperature at constant strain rate.

During plastic deformation of a polycrystalline material, both the grain interior and the grain boundary regions exhibit distinctly different dislocation behaviours at a given strain and temperature. Studying the variation of experimental flow stress with temperature, it seems that the flow stress of a fine grained polycrystalline material is mainly controlled by dislocation dynamics at and in the vicinity of grain boundaries. At low temperatures in a polycrystalline material, the dislocations are piled up at grain boundaries and the density of dislocations increases significantly in the grain boundary region, while at high temperatures the annihilation of dislocations take place at and in the vicinity of the grain boundaries during deformation. Therefore, the flow stress behaviour of a polycrystalline material can be understood in terms of the process of accumulation and annihilation of dislocations at and in the vicinity of grain boundaries at a given strain and temperature.

The use of thalloid liverwort Plagiochasma appendiculatum Lehm. et. Lind. by Gaddi tribes of Kangra Valley, Himachal Pradesh in India, for the cure of burns, boils, and blisters of skin is reported for the first time.

This paper reports 58 ethnomedicinal plants used by the Jaunsari tribe of the Dehradun district, Uttar Pradesh, India in the preparation of native medicines for the treatment of ailments. The Jaunsar-Bawar area of the district, inhabited by the Jaunsari tribe was surveyed during 1989–92 to gather information on the traditional uses of medicinal plants and to uncover new uses of known plants, used in health care by them. The study provides first-hand information on local name, locality, preparation of ethnomedicines, dosage and mode of administration. The district is rich in raw materials for establishing herbal drug industries.

Anaerobic fixed film reactors are characaterized by support media matrix which retain biomass both as a fixed film on the media and in the form of entrapped floes or sludge particles in the void spaces. The support media plays an important role in the treatment of wastewater. Fixed bed reactors have been operated on a wide variety of support material types, shapes and sizes, but a detail study regarding the size, shape, porosity, arrangement/packing of the media in an anaerobic reactor system is needed. Considering the above lacunae, preliminary screening experiments using different media of various particle sizes and attachment of pure culture of E. coli were studied. Later the studies were extended to volatile solid uptake also. The studies revealed that the activated carbon exhibiting 83.7% attachment of E. Coli is the best support matrix followed by refractory bricks exhibiting 79.7% attachment. But refractory brick is prefered over carbon as it is cheaper and can be reused again and again af...

CFD simulations of single-phase flow in a pulsed sieve plate column are presented. Several options to predict axial dispersion in this computationally challenging equipment are evaluated. The evaluation involves comparison of the two possible approaches of 2D representation of the 3D geometry, comparison of a direct approach with a new approach called the snapshot approach and comparison of predictions for the computational domain consisting of the actual number of plates and the computational domain consisting of reduced number of plates. A computational approach is finally prescribed and validated for quick estimate of axial dispersion in single-phase flow.