The Experts below are selected from a list of 2049 Experts worldwide ranked by ideXlab platform
John D Corbett - One of the best experts on this subject based on the ideXlab platform.
-
k23au12sn9 an intermetallic compound containing a large gold tin cluster synthesis structure and bonding
Inorganic Chemistry, 2010Co-Authors: Sungjin Kim, Gordon J Miller, John D CorbettAbstract:A polyanionic unit {Au12Sn9} with a novel “Corrugated Sheet” shape occurs in K23Au12Sn9. The compound was obtained by fusion of the pure elements in tantalum ampules at high temperatures followed by programmed cooling, and the structure was determined by X-ray diffraction: I42m (No. 121), a = 20.834(3), c = 6.818(1) A, Z = 2. The large heteroatomic cluster has D2d point symmetry and features a central four bonded (4b-) Sn, eight 3b- or 2b-Sn on the perimeter, and 24 linking nearly linear Sn−Au bonds at 12 Au atoms. Formula splitting according to the Zintl concept suggests that the compound is one electron deficient, and linear muffin-tin-orbital (LMTO) electronic structure calculations show that the Fermi level (EF) lies near a band gap at around 0.5 eV, that is, an incompletely filled valence band in concert with favorable atom packing. Large relative −ICOHP values for Au−Sn are consistent with the observed maximization of the number of heteroatomic bonds, whereas the numerous K-Sn and K-Au contacts con...
Ž.. Olujić - One of the best experts on this subject based on the ideXlab platform.
-
experimental characterization and modeling of the performance of a large specific area high capacity structured packing
Industrial & Engineering Chemistry Research, 2007Co-Authors: Ž.. Olujić, M Behrens, Lothar SpiegelAbstract:This paper presents the results of a comprehensive experimental study performed with a Sulzer high-capacity structured packing of a larger specific area, which provided a basis for validation of the Delft model. Purely geometry-based adaptations were made to the Delft model, to account properly for the effect of short smooth bends on both ends of each Corrugated Sheet, which, in turn, seemed to be beneficial for capacity without adversely affecting the efficiency. Comparisons indicate fairly good agreement with experiments as well as with the predictions of an in-house empirical model contained in Sulzer's software package, Sulpak.
-
hydrodynamic analogy based model for efficiency of structured packing columns
Aiche Journal, 2006Co-Authors: A Shilkin, Eugeny Y Kenig, Ž.. OlujićAbstract:A model based on the hydrodynamic analogy approach was developed for the prediction of temperature and composition profiles in structured packing distillation columns. Compared to the traditional models based on the film theory, the proposed model is more rigorous. It comprises Navier-Stokes equations, convection-diffusion and heat-conduction equations to describe the transport phenomena under condition of two-phase gas-liquid flow in an entire separation column. As a result, modeling the column efficiency is accomplished without application of the mass-transfer coefficients. For the model verification, total reflux distillation data for binary and multicomponent mixtures are used. Calculations with both the hydrodynamic-analogy-based, and the film model are performed for a wide range of operating conditions. The proposed model is shown to have a more stable performance than the traditional one. Therefore, it can be recommended for design, revamp and optimization of distillation columns equipped with Corrugated Sheet structured packings. © 2006 American Institute of Chemical Engineers AIChE J, 2006
-
effect of column diameter on pressure drop of a Corrugated Sheet structured packing
Chemical Engineering Research & Design, 1999Co-Authors: Ž.. OlujićAbstract:The results of an experimental study indicating a significant effect of column diameter on the pressure drop and capacity of Corrugated Sheet structured packing are presented. The experiments were carried out with Montz-pak B1-250, using an air/water system at ambient conditions in perspex columns with internal diameters of 0.2 m, 0.45 m, 0.8 m and 1.4 m. The results clearly show that both the pressure drop increase and capacity decrease become significant when the column diameter approaches the value equal to that of the height of a packing element. This observation suggests that column diameter(s) based on small scale data can be too large.
S Kitipornchai - One of the best experts on this subject based on the ideXlab platform.
-
vibration analysis of Corrugated reissner mindlin plates using a mesh free galerkin method
International Journal of Mechanical Sciences, 2009Co-Authors: K M Liew, L X Peng, S KitipornchaiAbstract:A mesh-free Galerkin method for the free vibration analysis of unstiffened and stiffened Corrugated plates is introduced in this paper, in which the Corrugated plates are simulated with an equivalent orthotropic plate model. To obtain the corresponding equivalent elastic properties for the model, a constant curvature state is applied to the Corrugated Sheet. The stiffened Corrugated plates are treated as composite structures of equivalent orthotropic plates and beams, and the strain energies of the plates and beams are added up by the imposition of displacement compatible conditions between the plate and the beams. The stiffness matrix of the whole structure is then derived. The proposed method is superior to the finite element methods (FEMs) because no mesh is needed, and thus stiffeners (beams) do not need to be placed along the mesh lines and the necessity of remeshing when the positions of the stiffeners change is avoided. To demonstrate the accuracy and convergence of the proposed method, several numerical examples are analyzed both with the proposed method and the finite element commercial software ANSYS. Examples from other research are also employed. A good agreement between the results for the proposed method, the results of the ANSYS analysis, and the results from other research is observed. Both sinusoidally and trapezoidally Corrugated plates are studied.
-
analysis of stiffened Corrugated plates based on the fsdt via the mesh free method
International Journal of Mechanical Sciences, 2007Co-Authors: L X Peng, K M Liew, S KitipornchaiAbstract:The elastic bending of unstiffened and stiffened Corrugated plates is studied in this paper, and a mesh-free Galerkin method is presented for the analyses. A Corrugated plate is treated as an orthotropic plate that has different flexure properties in two perpendicular directions. The equivalent flexure properties are estimated by applying constant curvature conditions to the Corrugated Sheet. The stiffened Corrugated plate is considered as a composite structure of an orthotropic plate with beams. By superimposing the strain energy of the orthotropic plate and the beams, and imposing the displacement compatibility conditions between the plate and the beams, the stiffness matrix of the structure is obtained. Because no mesh is needed in the proposed method, there is no limitation to the position of the stiffeners (beams). Changes in the positions of the stiffeners do not require the re-meshing of the plate. Several numerical examples are employed to show the accuracy and convergence of the proposed method. The computation results demonstrate good agreement with the solutions given by ANSYS, and different profiles of Corrugated plates are considered.
Sungjin Kim - One of the best experts on this subject based on the ideXlab platform.
-
k23au12sn9 an intermetallic compound containing a large gold tin cluster synthesis structure and bonding
Inorganic Chemistry, 2010Co-Authors: Sungjin Kim, Gordon J Miller, John D CorbettAbstract:A polyanionic unit {Au12Sn9} with a novel “Corrugated Sheet” shape occurs in K23Au12Sn9. The compound was obtained by fusion of the pure elements in tantalum ampules at high temperatures followed by programmed cooling, and the structure was determined by X-ray diffraction: I42m (No. 121), a = 20.834(3), c = 6.818(1) A, Z = 2. The large heteroatomic cluster has D2d point symmetry and features a central four bonded (4b-) Sn, eight 3b- or 2b-Sn on the perimeter, and 24 linking nearly linear Sn−Au bonds at 12 Au atoms. Formula splitting according to the Zintl concept suggests that the compound is one electron deficient, and linear muffin-tin-orbital (LMTO) electronic structure calculations show that the Fermi level (EF) lies near a band gap at around 0.5 eV, that is, an incompletely filled valence band in concert with favorable atom packing. Large relative −ICOHP values for Au−Sn are consistent with the observed maximization of the number of heteroatomic bonds, whereas the numerous K-Sn and K-Au contacts con...
ž Olujic - One of the best experts on this subject based on the ideXlab platform.
-
large diameter experimental evidence on liquid mal distribution properties of structured packings
Chemical Engineering Research & Design, 2015Co-Authors: ž Olujic, Helmut JansenAbstract:Abstract Comprehensive liquid distribution experiments were conducted with common-size conventional and high-capacity, Corrugated-Sheet structured packings in a 1.4 m internal-diameter column hydraulics simulator using air/water test system at ambient conditions. The objective of the present study was to observe and quantify for various liquid loads and bed depths the relation between the quality of liquid distribution of a packed bed and uniformity and density of initial irrigation profiles, and, in particular, to demonstrate the effects of severe forms of initial liquid maldistribution.
-
a general correlation for predicting the loading point of Corrugated Sheet structured packings
Industrial & Engineering Chemistry Research, 1999Co-Authors: Huibjan Verschoof, ž Olujic, James R FairAbstract:Comprehensive experimental studies have been conducted with several varieties of commercial structured packing to ascertain geometry-imposed effects on their hydraulic behavior. At Delft, the air−water system was used for hydraulic studies, and at the Separations Research Program (SRP) the cyclohexane/n-heptane distillation system was used to provide additional hydraulic and mass-transfer data for the same packings. These and other performance data available in the SRP database have been used to substantiate the development of a physically sound, generally applicable empirical correlation for predicting the onset of loading, where hydraulic characteristics of the packed bed change significantly. The correlation proposed in this paper covers a wide range of operating conditions and variations in structured packing geometry. It can be used with either Delft or SRP preloading models to provide an outgoing point for determining pressure drop, liquid holdup, and mass transfer in the loading region.
-
development of a complete simulation model for predicting the hydraulic and separation performance of distillation columns equipped with structured packings
Chemical and Biochemical Engineering Quarterly, 1997Co-Authors: ž OlujicAbstract:This paper describes the work oriented toward the development of an advanced expert system capable of predicting the hydraulic and separation performance of Corrugated Sheet structured packings. The simulation programme consists of a number of modules covering different types of performance calculations. Traditional, overall approach relying on the assumption of plug flow of both phases is represented by a newly developed method, which unlike the known methods accounts explicitly for the effects imposed by micro and macro characteristics of packing geometry. A special feature of this method is that the effective areas are determined using the author's small scale liquid distribution method. This liquid flow distribution model represents the hart of a detailed calculation approach. The gas flow profile is assumed to be uniform and the established liquid distribution pattern enables the calculation of local L/V values which are used together with other relevant information's in a separate module to calculate the concentration changes along the bed and consequently the corresponding HETP value. A separate module is used to visualise the liquid flow pattern in the bed. Any kind of initial liquid distribution profile can be arranged, however, a separate module can be used to evaluate the performance of commercially available high performance liquid distributors. Generally the detailed model is designed to predict the mass transfer efficiency of a column operating in the preloading range, and is particularly suitable for the prediction of the effects of varying degrees of small scale liquid maldistribution. This in turn enables the determination of the optimum quality of initial liquid distribution for a given packing and creates a basis for optimisation of packing geometry. Present developments of the model and related software are discussed as well as the future refinements and improvements.
