Andrei Kolesnikov | TUT - Academia.edu (original) (raw)

Papers by Andrei Kolesnikov

Nanomaterials

The rate of sorption of n-butane on the structurally flexible metal-organic framework [Cu2(H-Me-t... more The rate of sorption of n-butane on the structurally flexible metal-organic framework [Cu2(H-Me-trz-ia)2], including its complete structural transition between a narrow-pore phase and a large-pore phase, was studied by sorption gravimetry, IR spectroscopy, and powder X-ray diffraction at close to ambient temperature (283, 298, and 313 K). The uptake curves reveal complex interactions of adsorption on the outer surface of MOF particles, structural transition, of which the overall rate depends on several factors, including pressure step, temperature, as well as particle size, and the subsequent diffusion into newly opened pores. With the aid of a kinetic model based on the linear driving force (LDF) approach, both rates of diffusion and structural transition were studied independently of each other. It is shown that temperature and applied pressure steps have a strong effect on the rate of structural transition and thus, the overall velocity of gas uptake. For pressure steps close to ...

Chemical Communications, 2021

We develop a new quantitative molecular theory of liquid-phase dipolar polymer gels. We describe ... more We develop a new quantitative molecular theory of liquid-phase dipolar polymer gels. We describe the gel collapse induced by electrostatic interactions in the good solvent regime.

Physical Chemistry Chemical Physics, 2021

Polymeric ionic liquids are emerging polyelectrolyte materials for modern electrochemical applica... more Polymeric ionic liquids are emerging polyelectrolyte materials for modern electrochemical applications.

Langmuir, 2018

We present a new model of adsorption-induced deformation of mesoporous solids. The model is based... more We present a new model of adsorption-induced deformation of mesoporous solids. The model is based on a simplied version of Local Density Functional Theory in the framework of solvation free energy. Instead of density, which is treated as constant here, we used the lm thickness and pore radius as order parameters. This allows us to obtain a self-consistent system of equations describing simultaneously the processes of gas 1

Current Digest of the Russian Press, The, 2018

Journal of Physics: Conference Series, 2019

This paper accords the likelihood of applying Donnan and Steric Partitioning Pore Model (DSPM) to... more This paper accords the likelihood of applying Donnan and Steric Partitioning Pore Model (DSPM) together with extended Nernst-Planck model to elucidate the capacity of charge and Donnan exclusion mechanisms in removing ions from simulated wastewater in Nano-Pro-3012 membrane filtration process. The extended Nernst-Planck model reports the transportation of cations across Nano-Pro-3012 with respect to electrical potential gradient, movement of solutes and pressure difference through the membrane. The working principle of these two equations is dependent on the adsorption of the charged surface, diffusion and convective transport. This principle was established with a software called Comsol multi-physic 4.3b to explain the capacity of charge and Donnan exclusion mechanism of Nano-Pro-3012. The extended Nernst-Planck model and the Darcy law model were applied to evaluate the physical interrelationship amidst Nano-Pro-3012 and ionic solutions with the aim of having a good understanding of the transport and rejection working operation of the ions. The principle of these equations was first used to envisage the capability of Nano-Pro-3012. The data obtained were validated with the laboratory data. There was an establishment that movement of solutes across the membrane bring about diffusion transport. The total flux in solution increases due to the working operation of the diffusion which in turns reduces the electrical potential, as a result, reduces the flux in the membrane. Ions smaller than pore sizes are rejected and the theoretical data is in conformity with the experimental data.

PJCT, 2012

Simulation and control of nanoparticle size distribution in a high temperature reactor This work ... more Simulation and control of nanoparticle size distribution in a high temperature reactor This work focuses on the modeling, simulation and control of particle size distribution (PSD) during nanoparticle growth with the simultaneous chemical reaction, nucleation, condensation, coagulation and convective transport in a high temperature reactor. Firstly, a model known as population balance model was derived. This model describes the formation of particles via nucleation and growth. Mass and energy balances in the reactor were presented in order to study the effect of particle size distribution for each reaction mechanisms on the reactor dynamics, as well as the evolution of the concentrations of species and temperature of the continuous phase. The models were simulated to see whether the reduced population balance can be used to control the particle size distribution in the high temperature reactor. The simulation results from the above model demonstrated that the reduced population bala...

MATEC Web of Conferences

A 3D model was proposed that describes the in-flight behavior of titanium particles in the plasma... more A 3D model was proposed that describes the in-flight behavior of titanium particles in the plasma environment, developed in the commercial CFD Ansys Fluent software, which described the heating of particles. The rate of evaporation was investigated based on the gas compositions, and the mass evaporated on the surface of the particle along the trajectory under plasma conditions. To evaluate the spheroidization rate of titanium particles, the calculated temperature and flow histories were established. Significant heat exchange behaviors are presented due to the variations in hydrogen content and feed rate. The simulation results have demonstrated that the range of 0-4% of H2 and at a low injection feed rate of 3-10 g/min minimized the evaporation rate and increased the spheroidization rate of particles.

Advanced Materials for Renewable Hydrogen Production, Storage and Utilization, 2015

Hydrogen has been considered as an alternative source of fuel to the fossil fuel in future, most ... more Hydrogen has been considered as an alternative source of fuel to the fossil fuel in future, most especially, for mobile applications. However, a requirement is the safe, efficient and compact on-board storage of hydrogen. Reversible storage in metal hydride is promising, but adequate knowledge of materials system fulfills all requirements regarding hydrogen content is a major drawback, release temperature, and reversibility simultaneously. Hydrogen absorption-desorption in a metal hydride bed reactor can be modeled using different software such as FLUENT, CFD-ACE, and COMSOL Multiphysics. This book chapter will focus on the use of software COMSOL Multiphysics to simulate the diffusion and heating of hydrogen and metal hydride powder in both radial and axial directions. The model consists of system of partial differential equations (PDE) describing two-dimensional heat and mass transfer of hydrogen in a porous matrix. The influence of the operating parameters Temperature, Pressure, Concentration, Permeability and Thermal Conductivity on the rate of absorption-desorption of hydrogen in metal hydride will be fully discussed. The simulation results obtained could be applied to the on-board hydrogen storage technology, in particular for the hydrogen supply of a fuel cell for powering of a hydrogen fuel cell vehicle.

Polish Journal of Chemical Technology, 2012

Packed bed reactors using metal hydride are attracting a lot of attention as potential hydrogen s... more Packed bed reactors using metal hydride are attracting a lot of attention as potential hydrogen storage systems. Some operational and design variables are major constraints to obtain a proper infl ow/outfl ow of hydrogen into a metal hydride reactor. These variables include packed bed thermal conductivity, porosity, pressure and temperature distributions in the reactor during the absorption/desorption cycle. They also cause a mechanical stress induced by temperature gradient. In this paper, two dimensional models are implemented in COMSOL multiphysics to simulate the hydrogen fl ow, pressure and temperature distributions in the packed bed reactor during absorption/desorption cycle. Also, stresses in porous metal hydride induced by temperature variation in the heating/cooling cycle were evaluated. A possible effect of stress induced, porosity changes on diffusion and heating of hydrogen in both radial and axial direction in packed bed is discussed. The model consists of a system of p...

International Journal of Mineral Processing, 2013

The separation of iron ore in a prototype batch jig separator developed by Mintek in South Africa... more The separation of iron ore in a prototype batch jig separator developed by Mintek in South Africa, referred to as the Mineral Density Separator (MDS), can separate ore samples into multiple bulk density fractions, provided that narrow feed size ranges are used. In this study, the performance of the equipment is considered by use of iron ore particles coloured according to density. This facilitated visualization of the density composition of the stratified ores. The highest density iron ore (>4000 kg/m 3) could be separated efficiently from gangue material, but satisfactory stratification of lower density particles (<3600 kg/m 3) could not be achieved.

International Journal of Chemical Reactor Engineering, 2007

With the recent interest in the application of nanoscale metal and metal oxide particles, there i... more With the recent interest in the application of nanoscale metal and metal oxide particles, there is now interest in manufacturing these materials in larger quantities. A number of techniques have evolved for the synthesis of nanopowders. For metal and metal oxide nanoparticles where coalescence is the dominating growth mechanism, concentration and the timetemperature history of the nanoparticles resulting from the reactor design determines the final particle average diameter. In this paper, we present the results of controlled synthesis of alumina nanopowder in a three-jet plasmachemical reactor, where temperature and velocity distributions are controlled by the angle of impingement of the plasma jets. The flow and temperature fields for various impingement angles were measured by an enthalpy probe. The products were characterized by means of electron microscopy, XRD analysis, and BET analysis. The dependences of particle size on the operation parameters (injection velocity of raw m...

Journal of Power and Energy Engineering, 2013

In this study, n-butanol-diesel blends were burned in a turbo-charged, direct injection diesel en... more In this study, n-butanol-diesel blends were burned in a turbo-charged, direct injection diesel engine where the brake thermal efficiency, (BTE) or brake specific fuel consumption, (BSFC) was compared with that of ethanol-diesel or methanol-diesel blends in another study by other authors. The test blends used were B5, B10 and B20 (where B5 is 5% n-butanol by volume and 95% diesel fuel-DF). In this study, the BTE was higher and the BSFC improved more than in the other study. Because of improved BTE with increasing brake mean effective pressure, BMEP, the BSFC reduced, however the increased shared volume of n-butanol in DF increased BSFC. Adding n-butanol in DF slightly derated the torque, brake power output with increasing speed, and caused a fall in exhaust gas temperatures, (EGT) which improves the volumetric efficiency and reduces compression work. Therefore, a small-shared volume of n-butanol in DF fired in a turbo-charged diesel engine performs better in terms of BTE and BSFC than that of ethanol or methanol blending in DF.

Fuel, 2013

h i g h l i g h t s " Regulated emissions were compared with other similar study by other authors... more h i g h l i g h t s " Regulated emissions were compared with other similar study by other authors using biodiesel blending with diesel fuel. " There was great improvement in the reduction of the emissions using a small shared volume of n-butanol with diesel fuel. " Premixed combustion phase is distinguishable and amplified suggesting an effective air-to-fuel mixing process. " We recommended the use of n-butanol/diesel blend in a turbo-charged engine without any engine modifications.

Fuel, 2011

Methanol-to-diesel (MTD) means a synthetic diesel fuel, its raw material is methanol. And it is a... more Methanol-to-diesel (MTD) means a synthetic diesel fuel, its raw material is methanol. And it is a liquid alcohol ether mixture with appropriate amount of additives, which can be blended with diesel fuel at various levels. It was synthesized by methanol with 1,2-epoxypropane and epoxyethane using modified calcined Mg/Al hydroxides as catalysts. The test and study on the physical properties of MTD and the fuel consumption and emissions of diesel engine using the mixed MTD and diesel fuel have been performed. The results indicates that there was no significant difference in the power values of diesel and the blend fuels while fuel consumption increasing around 14%, and of much lower emissions of exhaust. When using the diesel fuel mixed with 20-30% of MTD. The conclusion is that MTD is a cheap and clean low power loss additive fuel for diesel engines.

Waste Management and the Environment VI, 2012

Korean Journal of Chemical Engineering, 2015

The nanofiltration (NF) process is electrostatically governed and the surface free energy plays a... more The nanofiltration (NF) process is electrostatically governed and the surface free energy plays a key role in the separation of particulates, macromolecules, and dissolved ionic species. Streaming potential measurement and the surface charge mapping by Kelvin probe atomic force mircoscopy (AFM) have been carried out. Forces of interaction near the surface of nanofiltration membranes were further studied by a force spectroscopy using atomic force microscopy. The two membranes used are more negatively charged at high pH values; hence the higher the solution chemistry, the higher and faster will be adhesion of ions on the surface of the nanofiltration membranes. It was observed that the three acquired signals from non-contact AFM (contact potential difference, amplitude and phase) were rigorously connected to the surface structure of the nanofiltration membranes. In addition to the surface structure (roughness), electrostatic interactions can also enhance initial particle adhesion to surfaces of nanofiltration membranes. The performance of the NF membranes was further investigated for the removal of nickel ions from aqueous solution, and the results were correlated to the mechanical responses of the nanofiltration membranes obtained from AFM and the streaming potential measurement.

Journal of Computational and Theoretical Nanoscience, 2013

This work was studied to determine the flux decline during nanofiltration of iron and deionised w... more This work was studied to determine the flux decline during nanofiltration of iron and deionised water. The rejection characteristic of iron was also studied. A stirred-cell was used for the experiment and Inductively Coupled plasma optical emission was used for iron analysis at various pH and pressure. The significant increased in flux declined at pH 3.01 and 3.44 is possibly caused by crystallized solids formed at the surface of the membrane and thus lead to the reduction of iron rejection at pH 3.01 and 3.44. At higher pressure more water passes through the membrane, thereby increasing the iron rejection. Experiment of clean water flux was done using the deionised water after the different pH experiment to see if the membrane is not fouling. The rejection characteristic of iron was also studied.

Journal of Computational and Theoretical Nanoscience, 2011

Aerosol processes are often model using the population balance equation (PBE). This article prese... more Aerosol processes are often model using the population balance equation (PBE). This article presents a study on the simulation of particle size distribution during nanoparticle growth with simultaneous chemical reaction, nucleation, condensation and coagulation. The method used to reduce the population balance model is the method of moments. Under the assumption of lognormal aerosol size distribution, the method of moments was employed to reduce the original model into a set of first-order ODE's (ordinary differential equations) that accurately reproduce important dynamics of aerosol process. The objective of this study is to investigate if we can use the reduced population balance model for the control of nanoparticle size distribution and to investigate the process model sensitivity to the influence of disturbance. And subsequently use the model to control particle size distribution. The numerical result shows there is a dependence of the average particle diameter on the wall temperatures and disturbance has great influence on process model. The process model was used as a basis to synthesize a feedback controller where manipulated variable is the wall temperature of the reactor and the control variable the aerosol size distribution at the outlet of the reactor.

Improvement Trends for Internal Combustion Engines

The use of biofuels that include n-butanol in diesel fuel (DF) is attracting attention in the sea... more The use of biofuels that include n-butanol in diesel fuel (DF) is attracting attention in the search for the reduction of emissions into the environment due to the burning of fossil fuel. The performance and combustion characteristics were evaluated in this study using blends B5, B10, and B20 (B5: 5% n-butanol and 95% DF) in a turbo-charged direct injection compression ignition engine. In the n-butanol diesel studies, a comparison was made with other studies that also included biodiesel in order to determine how suitable n-butanol-diesel blends were to use in internal combustion engines. Combustion characteristics of B20 (n-butanol 20% and 80% DF) improved when the study was compared with a similar study that included 40% biodiesel added to B20. A higher value of the standard deviation for DF than the blends was observed from the standard deviation diagram, indicating a more stable combustion process for the blends than DF. Soot reduction relative to DF at 1500 rpm at 75% load for B05, B10, and B20 mixtures was 55.5, 77.8, and 85.1%, respectively. This reduction is a significant advantage of blending DF with smaller shared volumes of bioalcohol.