Extension of the Rapid Design Algorithm for Twisted‐Tube Evaporative Fluid Coolers

The thermal analysis performance of evaporative fluid coolers (EFCs) is improved by replacing plain tubes by twisted oblong tubes. Results of the system are assessed by a rapid design algorithm (RDA) and compared to conventional plain‐tube EFCs and other traditional algorithms including the effectiveness number of transfer units (?‐NTU). Based on the RDA, a relationship between heat transfer coefficients, pressure drops, heat transfer area, and mass transfer coefficient is derived. Using the maximum allowable pressure drops in this algorithm, the minimum required heat transfer area can be determined. The algorithm is validated by comparing the plain‐tube EFC design with twisted‐tube design. The RDA‐designed EFCs with twisted tubes provide higher efficiency compared with the traditional designs with plain tubes in such that the new design needs a lower heat transfer area for a given heat load.     

CFD Simulation of Gas Distribution Performance of Gas Inlet Systems in Packed Columns

Packed columns are widely used in the chemical process industries. The optimum operation of these columns requires an even distribution of gas and liquid flows. This paper describes a method for modeling the flow pattern which develops above the gas inlet system using a computational fluid dynamics (CFD) approach. The uniformity of the gas flow through the packing is assessed by means of a maldistribution factor, M_F. Several factors which affect gas distribution, such as gas inlet type, gas inlet diameter and the distance between gas inlet and column bottom, were analyzed. It was found that gas distribution is more uniform as the inlet diameter and bottom distance are increased. Comparison of experimental data with a CFD simulation for several types of gas inlets, such as straight, slope and bend inlets, shows good agreement.     

CFD Simulation of Mass Transfer Efficiency and Pressure Drop in a Structured Packed Distillation Column

The pressure drop and mass transfer efficiency for two‐phase flow in a structured packed column were simulated using a commercial CFD package, CFX version 10. The distillation of the methanol/isopropanol system was carried out in a 0.073 m diameter column, with an element composed of a ceramic structured packing and 0.053 m in height. The Height Equivalent to Theoretical Plate (HETP) value varied from 0.106–0.146 m. Pressure drop experiments were measured with an air/water system. The pressure drops at the flooding and loading points were ca. 173 and 580 Pa/m of packing, respectively. HETPs and pressure drops calculated from the Computational Fluid Dynamics (CFD) model were compared to their experimental counterparts. The average relative error between CFD predictions and the experimental data for the prediction of dry pressure drop, irrigated pressure drop and mass transfer efficiency are 20.3 %, 23 % and 9.15 %, respectively. In all cases, the CFD predictions show a good agreement with the experimental data, indicating that CFD is a reliable, cost saving and suitable technique for the design and optimization of separation processes.     

Forward osmosis desalination using pectin-coated magnetic nanoparticles as a draw solution

Clean Technologies and Environmental Policy - In this study, magnetic Fe3O4 nanoparticles and pectin-coated magnetic Fe3O4 nanoparticles were used as a potential draw solution in forward osmosis...     

Berries anthocyanins as potential SARS-CoV–2 inhibitors targeting the viral attachment and replication; molecular docking simulation

The viral respiratory disease, severe acute respiratory syndrome (SARS), has turned into a global health concern. Till now, there is no drug or vaccine has yet been specifically approved for SARS-CoV-2. One of the urgent solutions against the recent COVID-19 disease is the use of dietary molecules, which can be found abundantly in functional food. In the current study, we have conducted a molecular docking approach for eighteen dietary molecules belong to the subclass of anthocyanins, as potential inhibitors of the main protease and spike glycoprotein of SARS-CoV-2. Both selected targets, playing a vital role in attachment and replication of the virus. The results indicated that cyanidin-3-arabinoside exhibited the lowest binding energy and located onto the pocket through a sufficient number of hydrogen bonds with the main protease virus. However, pelargonidin-3-glucoside and pelargonidin 3-rhamnoside display significant binding energy with the spike glycoprotein of SARS-CoV-2. All compounds mentioned above shown high drug-likeness and fulfils the Lipinski’s rule of five, as well as confer favorable toxicity parameters, in addition to ADME values. Considering the obtained results, regular consumption of berry fruits, which are rich in anthocyanin compounds, should be supportive to inhibit viral infectious by reducing of propagation and pathogenicity of SARS-CoV–2.     

Recovery of nickel-base alloys from boiler deposits to produce stainless steel grades

Nickel-base alloys (55-60% Ni) are produced from a nickel-rich concentrate containing 37% NiO (obtained after separation of vanadium compounds from boiler deposits) using either carbon or metallothermic reduction processes. The influential factors that affect the optimum recovery of nickel and its content in the produced alloy are investigated.

The produced nickel-base alloys proved to be feasible for the production of some stainless steel grades comparable with the standard specifications.     

Investigation of the effect of delayed reflux on PVC grain properties produced by suspension polymerization

The effects of the condenser operation on properties of polyvinyl chloride (PVC) particles produced by suspension polymerization process were investigated in a pilot scale reactor. It was observed that delaying reflux operation increased the cold plasticizer absorption of the final resin. Both bulk density and K‐value of the PVC powder decreased by increasing time delay in the reflux operation. It was also found that commencement of refluxing before 20% conversion resulted in bimodal particle size distribution (PSD), while monomodal PSD was obtained for longer delays in refluxing. SEM micrographs showed that surface of produced particles were rough and smooth when reflux started before and after 20% conversion, respectively. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Tuning Gas-Diffusion through Dynameric Membranes: Toward Rubbery Organic Frameworks (ROFs)

Obtaining high permeability whilst keeping a reasonable selectivity is the most important challenge in the development of membrane systems for gas separation. Satisfactory performance is usually obtained with polymeric membranes through which gas transport is controlled by gas-diffusivity in glassy polymers and by gas-solubility in rubbery polymers. During the last decade, important advances in this field have been made possible by molecular control of gas separation properties. The combination or replacement of classical glassy polymers with metal-organic crystalline frameworks (crystalline MOFs), such as zeolitic imidazolate frameworks (ZIFs) or other zeolites, provides reasonable permeability through the porous networks formed, and high selectivity, due to so-called ‘selectivity centers’, which interact specifically with the gas molecules. Despite impressive progress, difficulties in obtaining homogeneous, mechanically stable, thin layer MOFs on various supports have been encountered. Given the observed high permeabilities of rubbery polymers and their flexible casting properties, it should be very interesting to build rubbery organic frameworks (ROFs), as alternative materials for gas membrane separation systems. Here we use low macromolecular constituents and dialdehyde core connectors, in order to constitutionally generate ROFs. Distinct from rubbery polymeric membranes, the performance of the ROFs depends univocally on diffusional behaviors of gas molecules through the network. For all gases, a precise molecular composition of linear and star-type macromonomers generates an optimal free volume for a maximal diffusion through the matrix. These results should initiate new interdisciplinary discussions about highly competitive systems for gas separation, which are constitutionally controlled on a molecular scale.