Amir Khakpay

Bio: Amir Khakpay is an academic researcher from University of Tehran. The author has contributed to research in topics: Ionic liquid & Membrane. The author has an hindex of 7, co-authored 13 publications receiving 144 citations. Previous affiliations of Amir Khakpay include University of Mississippi.

Molecular Insights on the CH4/CO2 Separation in Nanoporous Graphene and Graphene Oxide Separation Platforms: Adsorbents versus Membranes

Abstract: Molecular dynamics simulations were performed to gain fundamental molecular insights on the concentration-dependent adsorption and gas transport properties of the components in a CH4/CO2 gaseous mixture in single- and double-layered nanoporous graphene (NPG) and graphene oxide (NPGO) separation platforms While these platforms are promising for a variety of separation applications, much about the relevant gas separation mechanisms in these systems is still unexplored Based on the gas adsorption results in this work, at least two layers of CO2 are formed on the gas side of both NPG and NPGO, while no adsorption is observed for pure CH4 on the single-layered NPG In contrast, increasing the CH4 concentration in the CH4/CO2 mixture leads to an enhancement of the CH4 adsorption on both separation platforms The through-the-pore diffusion coefficients of both CO2 and CH4 increase with an increase in the CH4 concentration for all NPG and NPGO systems The permeance of CO2 is smaller than that of CH4, suggestin

The effects of a surfactant on mean drop size in a mixer-settler extractor

Abstract: In this experimental study, the presence effect of Aniline surfactant on mean drop size, D 32 , was investigated in a horizontal mixer-settler For this purpose, two series of experiments were conducted in a single stage mixer-settler on the liquid–liquid dispersion of a toluene–water system At first, the effects of the impeller speed and the holdup on the drop size distribution were examined without Aniline Afterwards the same investigation was performed in the presence of Aniline For both experimental series, a new modified correlation for D 32 was presented The results revealed that D 32 , in the absence of Aniline, depended on the impeller speed with a power low function, having an exponent of −1208 and being in agreement with the Hinze-Kolmogorov's theory In the presence of Aniline, a greater reduction in D 32 was observed when the impeller speed increased Moreover, the increasing rate of D 32 diminished with the increase in the holdup

The effects of impeller speed and holdup on mean drop size in a mixer settler with spiral‐type impeller

Abstract: An experimental investigation has been carried out in order to analyse the drop size distributions of liquid–liquid dispersion in a single stage mixer settler extractor. In this paper, the effects of the impeller speed and the holdup on mean drops size, D32, have been investigated. D32 was decreased with an increase in the impeller speed. Furthermore, D32 was increased with an increase in the holdup. In addition, a new and modified correlation was established based on these results. The average absolute relative deviation is 3.36%. Une etude experimentale a ete effectuee pour analyser la repartition de la taille des gouttes pour la dispersion liquide-liquide dans un extracteur-decanteur-melangeur a etage unique. Dans cet article, on etudie les effets de la vitesse d'agitation et la retenue d'une goutte de taille moyenne, D32. D32 diminuait avec l'augmentation de la vitesse d'agitation. De plus, D32 augmentait avec l'augmentation de la retenue. Par ailleurs, une correlation nouvelle et modifiee a ete mise en place en se basant sur ces resultats. L'ecart relatif absolu moyen est de 3,36%.

Spray and packed liquid–liquid extraction columns: drop size and dispersed phase mass transfer

Abstract: The effects of holdup on Sauter mean drop diameter, D32, and dispersed phase mass transfer coefficient have been studied in the spray and packed extraction columns. For both columns, two well-defined regions for the dependence of D32 on holdup were observed. D32 increased and decreased with an increase in holdup at low and high levels of holdup, respectively. Changes in dispersed phase mass transfer coefficient against holdup were shown to be similar to D32 for both columns. Moreover, empirical correlations have been derived to predict D32 and dispersed phase mass transfer coefficient for both columns. It has been shown that the derived correlations are in a good agreement with the experimental data. © 2013 Curtin University of Technology and John Wiley & Sons, Ltd.

Fast parallel algorithms for short-range molecular dynamics

Abstract: Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

Trends in Solid Adsorbent Materials Development for CO2 Capture

Abstract: A recent report from the United Nations has warned about the excessive CO2 emissions and the necessity of making efforts to keep the increase in global temperature below 2 °C. Current CO2 capture t...

Physical meaning of the Sauter mean diameter of spherical particulate matter

Abstract: Diameter of a collection of different-size spherical objects such as particles, droplets, and bubbles can be represented by a single value called the mean diameter. There are many ways of calculating and expressing the mean diameter of particulate matter. One of them is the Sauter mean diameter also called the surface-volume mean diameter. This diameter has been extensively used in numerous publications without paying attention to its physical meaning. In this article, the physical meaning of the Sauter mean diameter of spherical objects was derived and presented. The Sauter mean diameter of a collection of spherical objects of different sizes is equal to the diameter of equisized spherical objects forming a collection. The polysized and equisized systems have different numbers of spherical objects, identical total surface area, and identical total volume. If the surface energy of all spheres of both systems is the same, they can be called equienergetic.