Volume 19, Issue 7 - Special Issue: Dedicated to the International Conference “Advances in Chemical Engineering-2020 (AdChE-2020)” UPES, Dehradun, India; Guest Editors: Santosh K. Gupta and Ajay K. Ray

The present study investigates the flow pattern characteristics of air-water co-current down-flow in millichannels. The experiments have been performed in glass tube of diameter 0.0042 and 0.008 m. The fluids are injected through Y entry the included angle between the Y arms being 45 ° , 90 ° , 135 ° , and 180 ° ( T Entry). The investigation reveals that the flow patterns are function of tube-diameter, and angle of fluid entry. Interestingly, stratified flow has been observed for steeper Y entry section at low liquid flow rates.

Flufenamic acid (FFA) is a Biopharmaceutical Classification System- II (BCS-II) class drug with poor bioavailability and a lower dissolution rate. Particle size reduction is one of the conventional approaches to increase the dissolution rate and subsequently the bioavailability. The use of the liquid antisolvent method for particle size reduction of FFA was studied in this work. Ethanol and water were used as solvent and antisolvent, respectively. Experimental parameters such as solution concentration (10–40 mg/ml), flow rate (120–480 ml/h), temperature (298–328 K) and stirring speed (200–800 rpm) were investigated. Furthermore, the solid dispersion of FFA was prepared with polyvinylpyrrolidone K-30 (PVP K-30) with different weight ratios (1:1, 1:2, 1:3 and 1:4) and samples were characterized using SEM, FTIR and XRD techniques. The experimental investigation revealed that higher values of concentration, injection rate, stirring speed, along with lower temperature favored the formation of fine particles. SEM analysis revealed that the morphology of raw FFA changed from rock-like to rectangular-like after liquid antisolvent recrystallization. FTIR analysis validated the presence of hydrogen bonding between FFA and PVP in solid dispersion. XRD analysis showed no significant change in the crystallinity of the processed FFA.

In this present work, forced convection heat transfer from a heated blunt-headed cylinder in power-law fluids has been investigated numerically over the range of parameters, namely, Reynolds number (Re): 1–40, Prandtl number (Pr): 10–100 and power-law index ( n ): 0.3–1.8. The results are expressed in terms of local parameters, like streamline, isotherm, pressure coefficient, and local Nusselt number and global parameters, like wake length, drag coefficient, and average Nusselt number. The length of the recirculation zone on the rear side of the cylinder increases with the increasing value of Re and n . The effect of the total drag coefficient acting on the cylinder is seen to be higher at the low value of Re and its effect significant in shear-thinning fluids ( n  < 1). On the heat transfer aspect, the rate of heat transfer in fluids is increased by increasing the value of Re and Pr. The effect of heat transfer is enhanced in shear-thinning fluids up to ∼ 40% and it impedes it’s to ∼20% shear-thickening fluids. In the end, the numerical results of the total drag coefficient and average Nusselt number (in terms of J H − factor) have been correlated by simple expression to estimate the intermediate value for the new application.

Endocrine disrupting compounds have been found to limit the natural working of the endocrine system like synthesis, secretion, transference and binding. Endocrine disrupting compounds are released from humans, animals and from production industries to soil, surface water and sediments mostly through the sewage treatment system. Studies have revealed the impact of these compounds on the nervous system, lungs, liver, thyroid, prostate, metabolism, obesity and reproductive system. So removal of these compounds from sewage water/wastewater by appropriate processes is essential. Conventional techniques like coagulation, precipitation, flocculation, microfiltration and ultrafiltration are effective for the removal of these compounds but limitations like low molecular weight of these compounds and pore size of membrane restricts the complete removal. Liquid membrane is a promising technology which combines the steps like extraction and stripping in a single step thereby providing the instantaneous removal and recovery of solutes and also results in high selectivity and savings of chemicals. This paper mainly focuses on the use of liquid membrane techniques like emulsion liquid membrane and hollow fiber supported liquid membrane which are the promising techniques for the removal of endocrine disrupting compounds from aqueous streams. The working principle, mechanism and implementation of these two techniques in the removal of several endocrine disrupting compounds from aquatic streams are also discussed.

Direct Numerical Simulations (DNS) were carried out for a freely falling/rising rigid particle in an otherwise quiescent fluid, using a non-Lagrangian multiplier based fictitious domain (FD) method. Validation studies showed that the proposed FD based DNS are in good agreement with the existing experimental results in the transition regime of falling/rising spheres. Simulations done in the transitional regime (50 < Reynolds number (Re) < 1800 and solid-to-fluid density ratios Γ=ρp/ρf${\Gamma}={\rho }_{p}/{\rho }_{f}$ from 0.08 to 4), confirmed that (i) a falling spherical particle (Γ = 4) exhibits a helical trajectory in the range 270 < Re < 320, and (ii) a rising particle (Γ = 0.5) shows a zig-zagging trajectory in the same range of Re. This finding closes the uncertainty to the question as to whether or not rising/falling particles exhibit a helical and a zig-zagging trajectory. In addition to this, a total of seven distinctive flow regimes were identified, which are as follows: (I) vertical straight path (II) steady oblique path (III) Wavy oblique path (IV) zig-zagging path (for 0.08 < Γ < 1) (V) helical path (for 1 < Γ < 4) (VI) early transition to chaos and (VII) chaotic regime. Regime IV occurs only for light particles (Γ < 1), whereas Regime V occurs only for heavy particles (Γ > 1). Fast Fourier Transform (FFT) analysis characterized the presence of a bimodal frequency similar to that exhibited by flow past an isolated stationary bluff body.

The utilization of nano-materials in a base fluid is a new dynamic technique to improve the thermal conductivity of base fluids. The suspension of tiny nanoparticles in base fluids is referred to the nano-materials. Nanofluids play a beneficial contribution in the field of nanotechnology, heat treatment enhancement, cooling facilities, biomedicine, bioengineering, radiation therapy and in military fields. The analysis of bioconvection characteristics for unsteady squeezing flow of non-Newtonian Jeffery nanofluid with swimming microorganisms over parallel disks with thermal radiation and activation energy has been studied in this continuation. The motivations for performing current analysis are to inspect the heat transfer enhancement in Jeffrey nanofluid in presence of multiple thermal features. The Jeffrey nanofluid contains motile microorganisms which convey dynamic applications in bio-technology and medical sciences and agricultural engineering. The system comprising differential equations of derivative is restricted to an ordinary one by means of a sufficient dimensionless similarity vector, and then implemented numerically by means of a famous shooting scheme with MATLAB tools. The effect of the significant parameters over the fluid flow is investigated from a physical point of view. The numerical findings of the modeled system are explored in detail using tabular data.

Concentrating solar power is the most challenging and expensive yet highly efficient source of thermal energy from solar power. This is mainly due to the intermittency of the sun rays and expensive materials used to harness its energy. One of the main components adding to the cost is the solar selective absorber materials which are simply put spectrally selective coatings on a receiver system to capture maximum heat from the sun. These materials add to a large extent to the efficiency of converting the sun’s energy to thermal energy and in turn electricity. An ideal solar selective absorber possesses the property of absorbing maximum radiations in the solar spectrum and emit minimum in the thermal energy spectrum. In the current study, an inexpensive, simple and environment-friendly solar selective absorber is fabricated by a galvanic displacement reaction of copper nanoparticles on galvanised metal substrates. These copper nanoparticles have high absorptivity (0.8–0.9) by virtue of plasmon resonance property. The emissivity is low due to the highly reflective metal substrate. By varying size of the copper nanoparticles from 100 nm to 2 μm emissivity and absorptivity can be varied. However, achieving low emissivity and high absorptivity requires some optimising. The size depends on the concentration of precursor solution and immersion time of substrate. One of the remedies for controlling the deposition rate to tune the nanoparticle size and microstructure of deposited copper nanoparticle is by addition of a deposition inhibitor (e.g. Polyethylene glycol).

Emulsions prepared using different surfactants, including Span-80, BKC and CTAB, are studied for their stability and phenol remsoval efficiency. The effect of contacting pattern on ELM extraction efficiency is compared in Beaker – Stirrer apparatus and Bubble Flow Recirculation column. The emulsion prepared using Span-80 is relatively more stable than emulsions prepared using other surfactants. The emulsion stability during the extraction process is relatively higher in the Bubble Flow Recirculation column (15 min) than in the Beaker – Stirrer apparatus (10 min). At optimized conditions, the phenol removal efficiency of the emulsion prepared using Span-80 in Beaker – Stirrer apparatus is 96% and in Bubble Flow Recirculation column is 78%. Kinetic studies reveal that the extraction follows zeroth-order kinetics with an average phenol effective diffusivity of 0.0004 s at an initial phenol concentration ranging from 100–500 PPM.

The isolation of dye (methylene blue) by employing a foam fractionation technique with the assistance of a surfactant (sodium dodecyl sulfate) has been dealt with in this paper. This study also incorporated the comparison between contrasted and experimental columns. Taguchi methodology and grey relational analysis techniques were used to ascertain optimal conditions at which the column should be operated to achieve maximum percentage removal and enrichment ratio, for both the columns. The analysis of variance study suggested dye concentration to be the most influencing parameter. The relationship between dye concentration in the bulk phase and the foam phase was also deduced.

The present study reports result from research into vapor–liquid–liquid phase equilibrium for n -octane highly diluted in water and water highly diluted in n -octane blends, using a dynamic method implemented in a constant volume CREC-VL-Cell. In the CREC-VL-Cell, a very high level of mixing is achieved, allowing for dispersions to be formed in the liquid phase and good mixing in the gas phase. This VL-Cell and its auxiliary equipment provide an increasing temperature ramp in the 30–110 °C range. It is found that the CREC-VL-Cell is of special value, for studying immiscible or partially miscible blends, such as is the case of n -octane in water. With the data obtained, which includes vapor pressures and temperatures, data analyses involving mass and molar balances, allow establishing overall liquid and vapor molar fractions. The recorded vapor pressures together with the calculated liquid and vapor molar fractions offer valuable data for VL thermodynamic model discrimination. For instance, it can be shown that vapor pressures, vapor and liquid molar fractions, as calculated with the Aspen-Hysys Peng Robinson Equation of State (Hysys-Aspen PR-EoS) provide only a first approximation of the experimental data, with significant discrepancies in the prediction of an n -octane disengagement temperatures. Thus, the determination of combined measured vapor pressures and calculated overall liquid molar fractions in the CREC-VL-Cell, offers a valuable and accurate procedure for thermodynamic model validation and discrimination.