Computational fluid dynamics simulations of phase separation in dispersed oil-water pipe flows

The separation of liquid–liquid dispersions in horizontal pipes is common in many industrial sectors. It remains challenging, however, to predict the separation characteristics of the flow evolution due to the complex flow mechanisms. In this work, Computational Fluid Dynamics (CFD) simulations of the silicone oil and water two-phase flow in a horizontal pipe are performed. Several cases are explored with different mixture velocities and oil fractions (15%-60%). OpenFOAM (version 8.0) is used to perform Eulerian-Eulerian simulations coupled with population balance models. The ‘blending factor’ in the multiphaseEulerFoam solver captures the retardation of the droplet rising and coalescing due to the complex flow behaviour in the dense packed layer (DPL). The blending treatment provides a feasible compensation mechanism for the mesoscale uncertainties of droplet flow and coalescence through the DPL and its adjacent layers. In addition, the influence of the turbulent dispersion force is also investigated, which can improve the prediction of the radial distribution of concentrations but worsen the separation characteristics along the flow direction. Although the simulated concentration distribution and layer heights agree with the experiments only qualitatively, this work demonstrates how improvements in drag and coalescence modelling can be made to enhance the prediction accuracy

Synthesis and Antimicrobial Evaluation of 5-Iodopyrimidine Analogs

4-Substituted-5-iodo-2-benzylthiopyrimidines were prepared efficiently in three steps. 2-Benzylthiopyrimidine on iodination in presence of base gave 5-iodo-2-benzylthiopyrimidine (1), which on chlorination with excess of POCl3 furnished 4-chloro-5-iodo-2-benzylthiopyrimidine (2). Reaction of 2 with substituted aromatic amines, 2-aminopyridine and hydrazine hydrate yielded 4-amino-5-iodo-2-benzylthiopyrimidines 3(a-e), (3f) and (3g) respectively. Further, 4-hydrazino-5-iodo-2-benzylthiopyrimidine on condensation with substituted aromatic and heterocyclic aldehydes afforded the corresponding schiff bases 4(a-h). The structure of synthesized compounds have been established by spectral studies and elemental analysis. Synthesized compounds have been screened for antimicrobial activity. Compound 3f exhibited good antifungal activity against A. niger. The compounds 4a, 4c, 4d, 4g and 4h exhibited good antibacterial activity