Current Issue : October - December Volume : 2012 Issue Number : 4 Articles : 8 Articles
A thorough review of the major parameters that affect solid-liquid slurry wear on impellers and techniques for minimizing wear\r\nis presented. These major parameters include (i) chemical environment, (ii) hardness of solids, (iii) density of solids, (iv) percent\r\nsolids, (v) shape of solids, (vi) fluid regime (turbulent, transitional, or laminar), (vii) hardness of the mixer�s wetted parts, (viii)\r\nhydraulic efficiency of the impeller (kinetic energy dissipation rates near the impeller blades), (ix) impact velocity, and (x) impact\r\nfrequency. Techniques for minimizing the wear on impellers cover the choice of impeller, size and speed of the impeller, alloy\r\nselection, and surface coating or coverings. An example is provided as well as an assessment of the approximate life improvement....
We introduce a numerical investigation of the effect of gravity on the problem of two-phase countercurrent imbibition in porous\r\nmedia. We consider three cases of inlet location, namely, from, side, top, and bottom. A 2D rectangular domain is considered for\r\nnumerical simulation. The results indicate that gravity has a significant effect depending on open-boundary location....
Highly ordered mesoporous materials are opening the door to new opportunities in catalysis due to their extraordinary intrinsic\r\nfeatures. In this study, Nickel was supported on highly ordered mesoporous silica (KIT-6) by the wet impregnation method, and its\r\nperformance in the hydrogenation of edible vegetable oil was compared with that of Ni/Activated carbon prepared using the same\r\nmethod as well as with unsupported Nickel. The degree of conversion for the 50 : 50 Ni/KIT-6 was 81%, as compared to the 29%\r\nobtained with 50 : 50 Ni/Activated carbons. The conversion was found to improve with an increase in mass of supported Nickel\r\non KIT-6 thus 20 : 80 Ni/KIT-6 and 30 : 70 Ni/KIT-6 produced conversions of 71% and 74%, respectively. Key among the benefits\r\nof KIT-6 when used as a support material is the very high surface area, open framework of the 3D bicontinuous interconnected\r\nchannels, and the well-ordered mesopores which bestow on it an advanced mass transfer characteristics....
The overall membrane pair characteristics included in the overall mass transport equation are understandable using the\r\nphenomenological equations expressed in the irreversible thermodynamics. In this investigation, the overall membrane pair\r\ncharacteristics (overall transport number ?, overall solute permeability �µ, overall electro-osmotic permeability f and overall\r\nhydraulic permeability ?) were measured by seawater electrodialysis changing current density, temperature and salt concentration,\r\nand it was found that �µ occasionally takes minus value. For understanding the above phenomenon, new concept of the overall\r\nconcentration reflection coefficient s* is introduced from the phenomenological equation. This is the aim of this investigation.\r\ns* is defined for describing the permselectivity between solutes and water molecules in the electrodialysis system just after an\r\nelectric current interruption. s* is expressed by the function of �µ and ?. s* is generally larger than 1 and �µ is positive, but\r\noccasionally s* becomes less than 1 and �µ becomes negative. Negative �µ means that ions are transferred with water molecules\r\n(solvent) from desalting cells toward concentrating cells just after an electric current interruption, indicating up-hill transport or\r\ncoupled transport between water molecules and solutes....
A Computational Fluid Dynamics (CFD) and response surface-based multiobjective design optimization were performed for\r\nsix different 2D airfoil profiles, and the Pareto optimal front of each airfoil is presented. FLUENT, which is a commercial CFD\r\nsimulation code, was used to determine the relevant aerodynamic loads. The Lift Coefficient (CL) and Drag Coefficient (CD) data\r\nat a range of 0? to 12? angles of attack (a) and at three different Reynolds numbers (Re = 68, 459, 479, 210, and 958, 422) for\r\nall the six airfoils were obtained. Realizable k-e turbulence model with a second-order upwind solution method was used in the\r\nsimulations. The standard least square method was used to generate response surface by the statistical code JMP. Elitist Nondominated\r\nSorting Genetic Algorithm (NSGA-II) was used to determine the Pareto optimal set based on the response surfaces.\r\nEach Pareto optimal solution represents a different compromise between design objectives. This gives the designer a choice to\r\nselect a design compromise that best suits the requirements from a set of optimal solutions. The Pareto solution set is presented in\r\nthe form of a Pareto optimal front....
Polymeric surfactants are important part of detergent formulation. Beginning as a partial replacement for environmentally undesirable phosphates as co-builder, polymers have several important benefits that enhance the laundering process. The polymers in detergent for the function of soil release, dye-transfer inhibition and enzymes that remove stains. STPP is very important in detergent formulation due to its sequestering property. Maleic vinyl ether was the first polymer used in detergent formulation as anti-redeposition agent in 1975. The extensive usage of petroleum products develops a global pressure on petroleum products. Moreover, these materials are big threat to the safe and healthy environment. In these circumstances we restrict the use of petroleum products by replacing them with renewable resources of natural origin. These Ecofriendly polymers have been synthesized form Sugar, Starch, Glycerol, Sorbitol, on the basis of their kinetic study and analyzed for different test, the best composition is used for the replacement of petroleum product in Powder and Liquid Detergents and compared with the commercial products....
We show that the gas-liquid flow pattern in a single gas-evolving electrochemical channel can be remarkably different from the\nflow pattern in multiple submerged gas-evolving electrochemical channels. This is due to the fact that in a single channel there is\na higher accumulation of small bubbles and these can considerably affect the liquid velocity pattern which in turn may affect the\nperformance of a cell. Since experimental work is often carried out in single channels, while industrial applications almost always\ninvolve multiple channels, this study provides insight into the factors that affect the flow pattern in each situation and establishes\nthe basis for relating the behavior of single-and multiple-channel devices....
Poly(vinyl chloride)/nitrile butadiene rubber (PVC/NBR) alloys were melt-mixed using a Brabender Plasticorder at 180?C and\r\n50 rpm rotor speed. Alloys obtained by melt mixing from PVC and NBR were formulated with wood-flour- (WF-) based olive\r\nresidue, a natural byproduct from olive oil extraction industry.WF was progressively increased from 0 to 30 phr. The effects of WF\r\nloadings on the tensile properties of the fabricated samples were inspected. The torque rheometry, which is an indirect indication of\r\nthe melt strength, is reported. The pattern of water uptake for the composites was checked as a function WF loading. The fracture\r\nmode and the quality of bonding of the alloy with and without filler are studied using electron scanning microscope (SEM)....
Loading....