Natural convection mass transfer inside cylindrical cavities of different orientation

Rates of free convection mass transfer inside cylindrical cavities were studied by measuring the limiting current for the cathodic deposition of copper from acidified copper sulphate solution using a cylindrical anode placed inside the cavity. Variables studied were cavity orientation (vertical with upward facing opening, vertical with downward facing opening and horizontal), physical properties of the solution and cavity dimensions (diameter and depth). For vertical cavities with upward facing openings the data were correlated by the equation Sh = 0.257 (Sc × Gr)^0.33 For horizontal cavities the data were correlated by the equation Sh = 0.139 (Sc × Gr)^0.33 For vertical cavities with downward facing openings the data were correlated by the equation Sh = 0.187 (Sc × Gr)^0.297 A comparison between the present data and the data obtained from other cavity geometries was made to shed light on the role of cavity geometry in thermosyphon design.List of symbols a, b constants - A cavity area - C copper sulphate bulk concentration - C _p specific heat - D diffusivity - d cavity diameter - F Faraday constant - g acceleration due to gravity - h heat transfer coefficient - I _L limiting current - k thermal conductivity - K mass transfer coefficient - L cavity depth - L _c characteristic length calculated from Equation 3 - Z number of electrons involved in the reaction - Gr Grashof number (gL _c ³/²/_i) - Nu Nusselt number (hL _c/k - Pr Prandtl number (C _pµ/k) - Sc Schmidt number (/D) - Sh Sherwood number (KL _c/D) - Ra Rayleigh number (Sc × Gr) or (Pr × Gr) Greek letters µ dynamic viscosity of the electrolyte - kinematic viscosity of the electrolyte - density of the electrolyte - _i interfacial density - density difference between the bulk solution and interfacial solution     

Fuzzy-based hunger games search algorithm for global optimization and feature selection using medical data

Neural Computing and Applications - Feature selection (FS) is one of the basic data preprocessing steps in data mining and machine learning. It is used to reduce feature size and increase model...     

A cleaner enzymatic approach for producing non-phthalate plasticiser to replace toxic-based phthalates

Clean Technologies and Environmental Policy - Dioctyl phthalate (DOP) is industrially commonly used as a polyvinyl chloride (PVC) plasticiser. As DOP does not form a chemical link with PVC, it...     

Epoxidized vegetable oil and bio‐based materials as PVC plasticizer

Phthalate esters received a considerable attention owing to its various applications and the harmful health effects resulting from phthalate exposure; thus, finding an alternative to phthalate derivatives became a necessity. Phthalate esters are commonly used as plasticizer in polymer formulation; in particular for poly(vinyl chloride) (PVC) formulation. According to the researches in the last 18 years, epoxidized vegetable oils are one of the alternatives that are strongly encouraged to substitute phthalate esters since they were proven to be valid in various applications, eco‐friendly and sustainable resource. However, most of the production practices for epoxidized vegetable oil are via conventional epoxidation that concentrates on a catalyst that is homogeneous and non‐reusable. This type of catalyst, however, causes several problems later in the process. Therefore, the selective epoxidation of vegetable oils process requires new catalytic systems that are more aligned with the green chemistry principles. This article reviews the harmful health effects associated with the exposure to phthalate esters products, explains the usage of oleochemicals resources as a substitute to phthalate esters and describes different approaches for the epoxidation of vegetable oils. Finally, it draws attention to the usage of epoxy and bio‐based compounds as plasticizers in PVC manufacturing. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46270.