Alireza Bahramian

Hamedan University of Technology · Chemical Engineering

The effect of particle size on the pressure profiles and flow regimes of the bed containing TiO 2 microparticles (MPs) was investigated in a fluidized bed. The fluidization behavior of particles with mean diameters, d p , of 170, 200, 225, and 300 μm at different gas velocities, U g , was investigated both experimental and computational viewpoints....

The present study evaluates elastic and inelastic contact forces in predicting the fluidization characteristics of irregularly shaped Titania nanoparticle agglomerates in a bench-scale conical fluidized bed. At first, experiments were performed to identify the mutual effects of gas velocity and agglomerate size on the instantaneous pressure, bed pr...

The hydrodynamic behavior of cohesive TiO2 nanoparticle agglomerates was studied in a conical fluidized bed. The effects of size, particle polydispersity, and airflow velocity were analyzed in the transition regime from heterogeneous to homogeneous and turbulent fluidization. The simple-agglomerates size was ~25–75 μm with fractal dimensions of ~1....

Acquiring new methods to achieve the products with lesser molecular weight associated with minimum energy consumption in poly(ethylene terephthalate) (PET) recycling can improve the glycolysis reaction performance. The synergistic effects of gamma irradiation on the properties of PET wastes and heat treatment on the catalytic activity of novel hydr...

The environmental sustainability, mechanical durability, and thermal stability of the poly(ethylene terephthalate) (PET)‐based nanocomposite films compared with pure PET were evaluated. The samples were obtained by incorporating 2 wt% of TiO2, SiO2, ZnO nanoparticles (NPs), and an equal mixture of NPs in polymer by melt‐mixing in a twin‐screw extru...

Optical-quality transparent, conducting polyaniline (PANI) thin films are suitable candidates for efficient counter electrodes for high-performance solar cells. In the first part of this work, the synthesis of highly uniform and homogenous nanostructured PANI films is reported. The film properties were assessed via scanning electron microscopy, ato...

The photocatalytic assessment of methanol conversion through cross-coupling reaction of methanol with its products was studied in a UV reactor consisting of platinum nanoparticles deposited onto a mesoporous TiO2 film. The temperature-programmed desorption (TPD) analysis showed excess methanol can affect the selective formation of formaldehyde, for...

The development of sustainable catalysts in the chemical recycling of polyethylene terephthalate (PET) can help to improve the circular economy of this material. In this study, the degradation of PET to the bis(2-hydroxyethyl) terephthalate (BHET) monomer and other main products was investigated by Mg–Al layered double hydroxides (LDHs) dispersed b...

The segregation behavior of a mixture of silica-coated titanium dioxide (TiO2) particles of three different sizes in a pseudo two-dimensional fluidized bed was studied experimentally by the freeze–sieving method and numerically by the multi-fluid model (MFM). Three-dimensional computational fluid dynamics (CFD) simulations were carried out to evalu...

Understanding the agglomeration process of nanoparticles (NPs) can help to decrease their adhesion during fluidization. Herein, the mutual effects between the mechanical properties and interparticle cohesive forces of the TiO2 NPs as well as the fluidization regimes were studied in a conical fluidized bed. Young’s modulus and hardness of the agglom...

TiO2 nanoparticles exhibit good photocatalytic activity for hydrogen evolution through water splitting; however, they demonstrate weak activity under visible light irradiation due to the wide band gap of TiO2. Deposition with noble metals such as platinum, as cocatalyst, led to the red-shift of the absorption edge of rutile TiO2; however, its activ...

The reliability and accuracy of numerical results of microparticle fluidization in a conical bed, affected simultaneously by mesh refinement, the grid configuration and the wall boundary condition (BC), are analyzed. Specifically, pressure gradients and velocity profiles of titania powder are studied for a conical bed. The Gidaspow drag correlation...

The fluidization characteristics of silver oxide nanoparticles (NPs) were studied in a bench-scale fluidized bed in this research. Hydrophobic NPs adhere to each other and form nano-agglomerates because of inter-particle forces, leading to bed channeling. The hydrodynamic behavior of the two-phase flow was investigated to gain insights into the tra...

TiO2 nano-particles (NPs) with an average primary size of 30 nm were fluidized by nitrogen and air in a bench-scale conical vessel. The NPs tended to form simple-agglomerates with porous structures because of weak physical inter-particle forces. When the NPs were fluidized, they agglomerated further to form complex-agglomerates with coral-like stru...

Determination of hydrodynamic characteristics and disinfection efficiency are important factors in the operational study of the ozone contactors. In the present work, a full-scale ozonation contactor for a municipal water treatment plant was simulated by computational fluid dynamics (CFD) approach. The Eulerian multiphase, κ – ϵ turbulence, and kin...

In the present study, for the first time, a full-scale experimental study of an ozonation contactor performance in a Municipal Surface Water Treatment Plant (MSWTP) in Hamedan, Iran was carried out over the course of one year. Effects of seasonal water characteristics and operating parameters were investigated on the removal of organic contents, mi...

This paper presents the computational fluid dynamics (CFD) simulation of a gas turbine combustor with methane-air fuel at atmospheric pressure. The velocity fields, temperature profile and species distributions have been numerically studied. The mathematical combustion models, namely Eddy Dissipation Concept (EDC) model coupled with detailed kineti...

To enhance photocatalytic degradation of organic pollutants, coral-like TiO2 nanostructured thin films were chemically synthesized through the sol-gel method. The fabricated thin films were characterized by Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), nitrogen sorption isotherms, mercury porosimetry measurements, and UV-Vis Diffuse...

The present work adopts experimental studies and molecular dynamics (MD) simulations to investigate the thermal, mechanical, and dynamical properties of polyaniline (PANI) coated on a TiO2 nanostructured film. At first, a series of the PANI and TiO2 nanostructured thin films were prepared using the sol-gel dip-coating method. The dynamic mechanical...

Dye-sensitized solar cell (DSSC) is the most promising of third generation solar cells for large scale applications due its low cost, flexibility, and scalable manufacturability. However, enhancing the efficiency of the DSSC is still highly desired. In this study, we designed a novel bifacial DSSC based on a transparent Polyaniline (PANI) films as...

To develop predictive models in nanostructured films, there is an ongoing research to validate molecular dynamics (MD) simulation results with experimental data. The morphology and surface topography of polyaniline (PANI) nanostructured film coated on a TiO2 nanocrystalline surface were investigated by scanning electron microscopy and atomic force...

Comprehensive exploration of the viscoelastic properties of polyaniline–emeraldine base (PANI–EB) nanostructured films is presented from two viewpoints of experimental study associated with dynamic mechanical thermal analysis and thermogravimetric measurements and of computational simulations by molecular dynamics (MD) approach. The results are exp...

The influence of drying temperature, T on the surface structure of polyaniline (PANI) nanostructured films dried at temperatures less than the glass transition temperature, T-g and between T-g and melting temperature, T-m was investigated by atomic force microscopy (AFM) and ZeScope optical profilometry. The expected power law behavior associated w...

The hydrodynamic performance of micrometric TiO2 particles has been experimentally studied in a conical fluidized bed and the results compared with numerical simulations. Local solid velocities in the bed have been measured by means of an optical fiber technique under different operating conditions of particle loading and air velocity. The radial p...

Effects of the deposition process parameters on the thickness of TiO2 nanostructured film were simulated using the molecular dynamics (MD) approach and modeled by the artificial neural network (ANN) and regression method. Accordingly, TiO2 nanostructured film was prepared experimentally with the sol–gel dip-coating method. Structural instabilities...

Coral-like TiO2 nanostructured films were chemically synthesized through the sol–gel method for fabrication of dye-sensitized solar cell (DSSC). The influence of experimental parameters such as precursor hydrolysis rate, reaction time, type and concentration of acid, and annealing temperature was studied through analysis of the surface structure of...

The fluidization characteristics of nanoparticle agglomerates have been experimentally and numerically studied in a fluidized bed. The experimental studies were carried out in a bed containing silver oxide dry powder belonging to group B of Geldart’s classification with a primary particle size of 30 nm. Pressure drop measurements using an optical f...

The numerical simulations and experimental data of bed hydrodynamics in a conical fluidized bed unit are compared. Experimental studies have been carried out in a bed containing TiO2 particles belonging to A/C boundary of Geldart's classification with a wide particle-size distribution. Thus, pressure measurements and an optical fiber technique allo...

The numerical simulat ions and experimen tal dat a of bed hydrodynam ics in a conical fluidized bed unit are compared. Experim ental stud ies have been carried out in a bed containing TiO 2 particles belonging to A/C boundary of Geldart’s classification with a wide particle-size distri bution. Thus, pressure measurements and an optical fiber tech-niqu...

In order to develop predictive process models in conical fluidized beds, there is an ongoing search for experimental methods and simulation tools to measure and model hydrodynamics parameters. Accordingly, experiments carried out in a conical fluidized bed containing micrometric TiO2 particles with a wide particle size distribution. An optical fibe...

Molecular dynamics simulation with an experimental work was performed on the TiO2 nanostructure film. The Morse potential function was used for the interatomic interactions. Then, the equations of motion for molecules and atoms are solved by Verlet algorithm. The effects of deposition rate and the number of TiO2 molecules were studied for morpholog...

Hydrodynamics characteristics and flow behavior of dried TiO 2 agglomerates have been studied experimentally and computationally in a conical lab-scale fluidized bed. The two-fluid flow model including kinetic theory of granular flow and agglomerates based approach was used in CFD simulations and their results were validated by comparison with the...

The hydrodynamics of gas-particle conical fluidized bed containing dried TiO(2) micro-size particles were studied experimentally and computationally. The pressure drop was studied by pressure measurements and mean solid velocity in the different axial and radial positions and their experimental values were measured by a parallel 3-fiber optical pro...

In this investigation, high transparent nanostructured TiO2 thin film has been prepared by a dip-coating method. The prepared sol was obtained through the hydrolysis of titanium isopropoxide under the selected pH. The transmission of film as an optical parameter was characterized by spectrophotometer. With respect to other experimental results, a h...