Numerical simulation of particle-laden flow in an industrial wastewater sedimentation tank

Meccanica - The wastewater of steel production factories consists of a large amount of very small metal particles. The metal particles in this wastewater enter a large sedimentation tank and are...     

A convenient synthesis of functionalized pyrazolones bearing a highly twisted 1,3-butadiene moiety with skew geometry

Abstract

The four-component reaction among arylhydrazine, alkyl acetoacetate derivatives, alkyl isocyanides, and dialkyl acetylenedicarboxylates, leading to the formation of dialkyl 2-[(Z)-(alkylamino)(3-alkyl-5-oxo-1-phenyl-1,5-dihydro-4H-pyrazol-4-ylidene)methyl] fumarates is described. The structure of target compounds was confirmed using X-ray diffraction study. These pyrazolone derivatives contain a highly twisted exocyclic 1,3-butadiene moiety with skew (??=?87°) geometry.     

Introducing the theory of successful settling in order to evaluate and optimize the sedimentation tanks

A rectangular settling tank in full scale is investigated using the Fluent software to increase its efficiency. First, the pure water is simulated in the absence of particles. Then particles are injected into the flow field and tracked by means of the discrete phase model. Three methods are presented to optimize the settling tank: (1) adding a baffle which is mounted in the bottom and is extended up to the near of free surface, (2) adding a baffle which is mounted in the free surface and is extended up to the near of the tank bottom and (3) install a bi-directional baffle which is mounted in the free surface and is extended up to the near of the bottom. These three suggestions are checked using the short-circuiting phenomenon and the successful settling theory. The successful settling theory states that a particle can be accounted as a “trapped” particle if (1) settled particle stays static and stable in the tank bottom and (2) settled particle doesn’t return to purified sewage. Although the second method provided higher efficiency, the third method was selected as the most appropriate method in order to optimize the settling tank.     

Investigating the possibility of increasing cooling air flow in a hydrogenerator rotor fan

Journal of Thermal Analysis and Calorimetry - The possibility of increasing cooling airflow inside a hydrogenerator rotor fan is investigated. The rotor fan has a heat dissipation problem and it is...     

Nef-isocyanide-Perkow access to novel pyrazolone derivations containing a cyclic ketene dithioacetal moiety

Alkyl (E)-2-(3-Alkyl-5-oxo-1-phenyl-1,5-dihydro-4H-pyrazol-4-ylidene)-5-(alkylamino)-1,3-dithiole-4-carboxylates have been obtained by condensation of 2-pyrazolin-5-ones with carbon disulfide followed by ring formation with phosphorylated hydroxyketenimines [generated in situ from Nef-isocyanide-Perkow reaction] in the presence of Et₃N. The structure of target compounds was confirmed by X-ray diffraction study. The good yields of the products, diastereoselectivity, and lack of activators or metal promoters are the main advantages of this method.     

Adsorption of tetraphenylphosphonium chloride at the mercury-water interface

Interfacial tersion measurements of mercury in contact with aqueous solutions of tetraphenylphosphonium chloride indicate the existence, at negative rational potentials, of an ordered monolayer of tetraphenylphosphonium ions, either as such or as its neutral salt. The analysis clearly illustrates the limits to the molecular information obtainable from electrical measurements.     

Revisit of wall‐induced lateral migration in particle electrophoresis through a straight rectangular microchannel: Effects of particle zeta potential

Previous studies have reported a lateral migration in particle electrophoresis through a straight rectangular microchannel. This phenomenon arises from the inherent wall‐induced electrical lift that can be exploited to focus and separate particles for microfluidic applications. Such a dielectrophoretic‐like force has been recently found to vary with the buffer concentration. We demonstrate in this work that the particle zeta potential also has a significant effect on the wall‐induced electrical lift. We perform an experimental study of the lateral migration of equal‐sized polystyrene particles with varying surface charges under identical electrokinetic flow conditions. Surprisingly, an enhanced focusing is observed for particles with a faster electrokinetic motion, which indicates a substantially larger electrical lift for particles with a smaller zeta potential. We speculate this phenomenon may be correlated with the particle surface conduction that is a strong function of particle and fluid properties.