Convection-dominated melting of phase change material in partially heated cavity: lattice Boltzmann study

Heat transfer and fluid flow processes of natural convection melting of a phase change material are simulated numerically inside a partially heated square cavity. The momentum and energy equations are solved by using enthalpy-based lattice Boltzmann method combined with multi distribution function model. In this communication, the dependence of liquid fraction, temperatures of vertical nodes and average Nusselt number on the positions of heated plates is investigated quantitatively.     

Thermal gradient effect on the free vibration of a cardioid cross-section cylindrical shell

For the first time, a new cross-section profile and efficient method are developed for the vibration analysis of isotropic and orthotropic cylindrical shells having circumferentially varying profile of a cardioid cross-section expressed as an arbitrary function, under thermal gradient effect. The governing equations of orthotropic cylindrical shells with varying thermal gradient around its circumference are derived as a boundary-value problem and solved numerically as an initial-value problem, based on the framework of Flügge's shell theory, transfer matrix approach and Romberg integration method. As a semi-analytical procedure, the trigonometric functions are used with Fourier's approach to approximate the solution in the longitudinal direction and also to reduce the two-dimensional problem to one-dimensional one. The thermal gradient is assumed to arise due to the variation of Young's moduli and shear modulus, along the circumferential direction of the shell. The results are obtained to indicate the effects of cardioid cross-section on the natural frequencies and corresponding mode shapes in the thermal environment as well as the sensitivity of the vibration behavior to the thermal gradient ratio and the orthotropy of the shell is also investigated for different types of vibration modes. In general, close agreement between the obtained results and those of other researchers has been found.     

Ageing characteristics of styrene-butadiene rubber containing some sulfanilyl derivatives

Styrene-butadiene rubber (SBR) mixtures containing some sulfanilyl derivatives have been prepared. The effect of the latter compounds on the rate of vulcanization of SBR formulations as well as the ageing characteristics of corresponding vulcanizates were evaluated. In all cases, the efficiency of the compounds under investigation was correlated with their chemical structure. It was found that vulcanizates containing sulfanilyl thiourea compounds deteriorate to a lesser degree than those containing N-isopropyl-N'-phenyl-1, 4-phenylenediamine (IPPD) as conventional antioxidant. In addition, the effect of the type of carbon black on the efficiency of such compounds as antioxidants was evaluated.     

Sorption of 60Co(II) from aqueous solutions onto biosynthesized zinc oxide nanocomposites

Journal of Radioanalytical and Nuclear Chemistry - Nano ZnO is biosynthesized using Lactobcillus sp. Poly Acrylic acid-co-Acrylonitrile/ZnO, PAACAN/ZnO, and poly Acrylic acid-co-Maleic acid/ZnO,...     

Experimental study of the subcooled flow boiling heat transfer of magnetic nanofluid in a vertical tube under magnetic field

Journal of Thermal Analysis and Calorimetry - In this study, the subcooled boiling heat transfer of a Fe3O4/water magnetic nanofluid flowing through a vertical tube has been investigated...     

The removal of methylene blue as a remedy of dye-based marine pollution: a photocatalytic perspective

Research on Chemical Intermediates - The effluents containing the discarded water from the textile industry are graded as one of the foremost pollutants in all industrial sectors. The wide...     

Spectroscopic,textural, electrical and magnetic properties of antimicrobial nano Fe(III) Schiff base complex

A novel Schiff base ligand (L) was prepared through condensation of 2,6‐diaminopyridine and dibenzoyl methane in a 1:1 ratio. This Schiff base ligand was used for complex formation reaction with Fe(III) chloride. The structures of the ligand and its complex were deduced from elemental analyses, mass spectroscopy, ¹H NMR, IR, UV‐Vis, electronic spectra, magnetic moment, molar conductivity measurements, thermogravimetric analyses and X‐ray diffraction. The molecular and electronic structures of both ligand and complex were optimized theoretically using density function theory (DFT) method. Moreover, the antimicrobial activities of the prepared compounds were studied and proven against some pathogenic bacteria. The Fe(III) complex had higher biological activity than that of the free ligand. Proceeding from the collected information, the properties of the complex were further investigated. The particle size was determined by dynamic light scattering technique to be 92.59 nm. Textural properties of the nano complex were studied by N₂ adsorption to estimate the specific surface area, pore volume and pore size distribution. The pores in the complex were found in the micropore–mesopore range. Differential scanning calorimetric measurements reveal the existence of four endothermic peaks at 243.8, 308, 339.8 and 380.5 K. Dielectric properties and conductivity were scanned at different frequencies and temperatures. The dielectric constant reaches a peak value of 600 at ~390 K, 30 Hz. A cross‐over from the universal dielectric response to the super linear power law of conductivity was reported for this complex at T ≤ 345 K. Finally, the AC‐magnetic susceptibility measurements were carried out in the low‐temperature region. The complex showed paramagnetic behavior with a slight change in the magnitude of its magnetic moment at T = 244 K.     

Simulation of natural convection melting in a cavity with fin using lattice Boltzmann method

In this study, a numerical investigation of melting phenomenon with natural convection in a cavity with fin has been performed using enthalpy‐based lattice Boltzmann method. The lattice D2Q9 model was applied to determine the density and velocity fields, and the D2Q5 model for the temperature field. The effect of vertical position and length of the fin on the melting rate was studied. The simulations were carried out for Stefan number of 10, Rayleigh number of 10 ⁵ and relative thermal conductivity (k_fin∕k_fluid) ranging from 5 to 30. The obtained results show that the rate of melting increases when the relative thermal conductivity and the length of the fin become greater. We also found that the variation of vertical position of the fin from bottom to middle has an insignificant effect on melting while it causes the increase of full melting time when the fin is mounted on the top of the cavity. Copyright © 2011 John Wiley & Sons, Ltd.