Alexandros N. Kalarakis

Alexandros N. Kalarakis
University of Peloponnese | UOP · Department of Mechanical Engineering

PhD in Chemical Engineering ; Bachelor of Science

About

56
Publications
7,914
Reads
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433
Citations
Citations since 2016
16 Research Items
298 Citations
20162017201820192020202120220102030405060
20162017201820192020202120220102030405060
20162017201820192020202120220102030405060
20162017201820192020202120220102030405060
Additional affiliations
September 2019 - present
University of Peloponnese
Position
  • Professor (Assistant)
Description
  • Full Time
April 2014 - September 2019
Technological Educational Institute of Western Greece
Position
  • Lecturer
Description
  • Full Time
September 2005 - April 2014
Technological Educational Institute of Western Greece
Position
  • Lecturer
Description
  • Part Time
Education
January 1997 - May 1999
University of Patras
Field of study
  • Chemical Engineering
January 1997 - December 2002
University of Patras
Field of study
  • Chemical Engineering
October 1991 - September 1996
University of Patras
Field of study
  • Physics

Publications

Publications (56)
Article
Inkjet‐printing technology is anticipated to play a forefront role in the future prototyping of perovskite solar cells (PSCs) to enable their ultra‐low‐cost and scalable manufacturing. However, key inkjet challenges related to fluid dynamics should be firstly addressed to allow the fabrication of high‐quality printed materials and subsequently comp...
Article
Full-text available
Up until now, the vast majority of perovskite solar cells (PSCs) have relied on the spin-coating of perovskite precursor solution under inert fully controlled conditions, with the performance of solar cells that are developed by alternative techniques and under an ambient atmosphere to lag far behind. This impedes the technology transfer from the l...
Article
Given the present research momentum, the development of efficient and stable ambient air-processed perovskite solar cells (PSCs) is of the core interests of scientists dealing with perovskites for photovoltaics. Hitherto, many suitable approaches are proposed to this aim. However, according to the authors' knowledge, none of them deals with the stu...
Article
A series of complex structured perovskites, with multiple cations and mixed I/Br halides, have been prepared and integrated in mesoscopic carbon based perovskite solar cells (PSCs). A comparative study has been performed among 4 different formulations and the beneficial role of Cs and Rb in this type of devices has been highlighted. Even though the...
Article
Full-text available
Solution electrospinning process (SEP) is a versatile technique for generating non-woven fibrous materials intended to a wide range of applications. One of them is the production of fibrous and porous scaffolds aiming to mimic bone tissue, as artificial extracellular matrices (ECM). In the present work, pure and nano-modified electrospun polyetheri...
Article
Full-text available
The diamagnetic two-dimensional Hofmann-type metal-organic framework [ZnII(2-mpz)2Ni(CN)4] has been successfully synthesized along with its isostructural hysteretic spin-crossover FeII analogue in the form of both bulk microcrystalline powder and nanoparticles. Detailed atomic force microscopy topographic study revealed a nanogrowth relationship be...
Article
Full-text available
Hydrogen and hydrogen peroxide have been photoelectrocatalytically produced by electrocatalytic reduction using simple carbon electrodes made by depositing a mesoporous carbon film on carbon cloth. Visible-light-absorbing photoanodes have been constructed by depositing mesoporous CdS/TiO2 or WO3 films on transparent fluorine-doped tin oxide (FTO) e...
Article
Full-text available
Crystalline TiO2 films were prepared on unheated glass substrates by radio frequency (RF) reactive magnetron sputtering at normal angle of incidence (a = 0°) and at glancing angle (a = 87°). The effect of the glancing angle on the structure, microstructure, and wetting properties of the films was investigated. The inclination of the substrate led t...
Article
A new type of electrochromic device that uses electrodeposition of lead(II) oxide in combination with hydrogel-stabilized water-based electrolyte has been investigated. Operation of selected devices was examined using a series of electrochemical techniques (cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy), along wi...
Article
In this study we present halloysite clay mineral combined with TiO2, as promising new class of nanomaterials that can be used as an effective, cost-efficient, and environment-friendly procedure for the decomposition of tebuconazole, C16 H22 ClN3 O, [(RS)-1-p-chlorophenyl-4,4-dimethyl-3-(1H-1,2,4-triazol-1-ylmethyl)-pentan-3-ol], TEB-fungicide, in w...
Article
The lattice-Boltzmann (LB) method is used in this work to reproduce the controlled addition of binder and hydrophobicity-promoting agents, like polytetrafluoroethylene (PTFE), into gas diffusion layers (GDLs) and to predict flow permeabilities in the through-and in-plane directions. The present simulator manages to reproduce spreading of binder and...
Article
Nanostructure Cu 2 ZnSnS 4 (CZTS) thin films were synthesized by Successive Ionic Layer Adsorption and Reaction (SILAR) method. The as-grown CZTS thin films have shown amorphous structure but after sul-furization at 450 °C temperature, CZTS thin films showed kesterite crystalline structure. The crystallite size of annealed CZTS thin films is to be...
Article
Perovskite solar cells (PSCs) with a composite mesoporous TiO2–In2O3 electron transport layer were constructed and tested. For the formation of the In2O3 overlayer three different molar concentrations of the precursor indium(III) acetylacetonate were investigated (TiO2–In2O3 (1) 46 mM, TiO2–In2O3 (2) 50 mM and TiO2–In2O3 (3) 56 mM). In2O3 was chose...
Chapter
Atmospheric pollution remains a major human health problem in most Greek cities. Motor vehicles are important sources of gaseous and particulate pollutants. In recent years, the situation is further perplexed due to the economic crisis and the use of woodstoves and fireplaces for residential heating. In order to measure and analyze the concentratio...
Conference Paper
Full-text available
Macroscopic two-phase flow in porous media is, in general, a mixture of connected and disconnected oil flow. The latter is expressed as ganglion dynamics and drop traffic flow. Disconnected flow is central in all modern simulators implementing pore network modeling. The computational effort, associated with the solution of the two-phase flow proble...
Conference Paper
Full-text available
AIM: The internal structure of a gas diffusion layer is responsible for its performance during fuel cell operation for energy conversion. The structural morphology and details are reproduced using computer-aided reconstruction techniques and are used as input to diffusion and flow computations to disclose the structure-to-property relationship as w...
Conference Paper
Full-text available
Operational maps for steady-state two-phase flow in porous media, delivered by implementing the DeProF model algorithm, were integrated within state-of-the-art FEM algorithms incorporating Darcian flow modules, in order to resolve field-scale 3D steady-state flows in porous media for different geometrical configurations.
Conference Paper
Full-text available
DeProF model predictions of o-w interfacial quantities have been incorporated in convection-diffusion algorithms in order to map the distribution of tracers with largely varying diffusion coefficient in the porous medium, and to quantify the effective diffusivities and dispersivities during mass transfer processes. The tracer transport is simulated...
Conference Paper
Full-text available
In this work the structure of gas diffusion layer, one of the key components of a fuel cell device, is computer-aided reconstructed. The reconstructions are used for the calculation of the gas diffusion layer diffusivity and permeability taking into account the effect of gas diffusion layer compression. The permeability is, also, investigated for t...
Conference Paper
Full-text available
Σε αυτήν την εργασία μελετώνται η δυνατότητα εφαρμογής, η ακρίβεια και η ταχύτητα σύγκλισης καινοτόμων απλεγματικών μεθόδων Meshless Local Petrov-Galerkin (MLPG) και μεθόδων Δικτύου-Boltzmann (LB) ως λύτες σε προβλήματα ροής, αγωγής και συναγωγής θερμότητας. Τα παραπάνω φαινόμενα επιλύονται σε πεπλεγμένες γεωμετρίες πορωδών μέσων στις δύο διαστάσει...
Conference Paper
Full-text available
Η υπολογιστική ρευστοδυναμική (CFD) αποτελεί ένα από τα πλέον ενδιαφέροντα και σύγχρονα επιστημονικά αντικείμενα στη μοντελοποίηση και προσομοίωση της ροής βιολογικών υγρών (αίματος ή ούρων) σε αγγεία και αρτηρίες και την εκτίμηση των ρευστοδυναμικών παραμέτρων αυτής. Δημοσιευμένες μελέτες σε πειραματικά μοντέλα και υπολογιστικές τεχνικές σε ομοιώμ...
Conference Paper
Full-text available
In general, macroscopic two-phase flow in porous media is a mixture of connected and disconnected oil flow. The latter is expressed as ganglion dynamics and drop traffic flow, flow patterns observed experimentally in pore network models [1,2] and real porous media [3,4]. This characteristic was adversely not taken into account in previous modeling...
Conference Paper
Full-text available
Operational maps for steady-state two-phase flow in porous media, delivered by implementing the DeProF model algorithm, were integrated within state-of-the-art FEM algorithms incorporating Darcian flow modules, in order to resolve field-scale 3D steady-state flows in porous media for different geometrical configurations. The mechanistic model DePro...
Conference Paper
Full-text available
Fuel cells (FCs) are devices that convert chemical energy to electricity and have the theoretical potential to operate at very high efficiency, while they are environmentally friendly since there are no pollutant emissions. A lot of research has been dedicated to the development of efficient and sustainable FC devices and significant progress has b...
Article
A numerical solution of the transient heat conduction problem with spatiotemporally variable conductivity in 2D space is obtained using the Meshless Local Petrov-Galerkin (MLPG) method. The approximation of the field variables is performed using Moving Least Squares (MLS) interpolation. The accuracy and the efficiency of the MLPG schemes are invest...
Conference Paper
Full-text available
True-to-mechanism relative permeability maps for steady-state two-phase flow in porous media were integrated within the COMSOL TM Earth Science module, to resolve field-scale flows. The essential characteristic of relative permeability dependence on local flow conditions (capillary number and flowrate ratio) have been provided by the DeProF model a...
Conference Paper
Full-text available
A numerical solution of transient heat conduction problem with variable conductivity in 2D space is obtained using the meshless local Petrov–Galerkin (MLPG) method. The essential boundary condition is enforced by the transformation method. The approximation of the field variables is performed using Moving Least Squares (MLS) interpolation. The accu...
Conference Paper
Full-text available
A numerical solution of steady-state heat conduction problem with variable conductivity in 2D space is obtained using the meshless local Petrov–Galerkin (MLPG) method. The essential boundary condition is enforced by the transformation method. The approximation of the field variables is performed using Moving Least Squares (MLS) interpolation. The a...
Article
The applicability and performance of the lattice-Boltzmann (LB) and meshless point collocation methods as CFD solvers in flow and conjugate heat transfer processes are investigated in this work. Lid-driven cavity flow and flow in a slit with an obstacle including heat transfer are considered as case studies. A comparison of the computational effici...
Article
Full-text available
Rarefied gas flow in channels and computer-aided reconstructions of porous media is simulated using the direct simulation Monte Carlo (DSMC) method and a modified lattice-Boltzmann (LB) method that can account for rarefaction effects. An increase of two orders of magnitude was noted for the gas permeability as the Knudsen number increased from 0.1...
Chapter
The accurate description of flow in nano-scale pores or channels is very important for the reliable design of materials and processes in the areas of MEMS, mesoporous media, and vacuum technologies. Use of classical flow equations fails in this regime since the continuum assumption is not valid. This is due to the fact that the mean free path is co...
Data
Full-text available
In recent years, novel numerical methods, such as the Meshless and the Lattice Boltzmann Methods (LBM), have been developed and extensively studied, providing alternative approaches to more traditional numerical techniques for the study of equilibrium and dynamic properties of fluid systems. In the present work, the efficiency of Meshless methods a...
Conference Paper
Full-text available
Protic ionic liquids and zeolites have been considered as potential means to improve the properties and performance of certain polymer electrolyte membranes in fuel cell applications. Zeolites with low Si/Al ratio are hydrophilic and can increase the membrane water content at elevated temperatures. Moreover, if such zeolites are encapsulated in a p...
Conference Paper
Full-text available
The observation that water molecules travel in carbon nanotubes (CNT) at a significantly higher speed than that predicted by fluid flow theory for pores or tubes of similar diameter using molecular dynamics [1], in combination with their high pollutant rejection efficiency, has stimulated numerous attempts to incorporate CNTs in water treatment app...
Conference Paper
Full-text available
Recent advances in micro- and nanotechnology have necessitated the elucidation of flow and diffusion processes under conditions that violate the continuum assumption and do not allow the safe application of phenomenological equations. A new lattice Boltzmann formulation is presented that accounts for rarefaction effects during flow in small channel...
Conference Paper
Full-text available
In recent years, novel numerical methods, such as the Meshless and the Lattice Boltzmann Methods (LBM), have been developed and extensively studied, providing alternative approaches to more traditional numerical techniques for the study of equilibrium and dynamic properties of fluid systems. In the present work, the efficiency of Meshless methods a...
Conference Paper
Full-text available
Η ροή αερίων σε πόρους και ψηφιακά ανακατασκευασμένα πορώδη μέσα μελετάται μέσω της μεθόδου DSMC. Υπολογισμός της εξάρτησης της διαπερατότητας από την πίεση έδειξε να συνάδει με τη θεώρηση Klinkenberg. Επιπρόσθετα αναπτύχθηκε ένα τροποποιημένο πρότυπο Dusty-Gas-Model το οποίο λαμβάνει υπ’ όψη την εξάρτηση του αποτελεσματικού ιξώδους από τον αριθμό...
Article
Full-text available
The effects of rarefaction on gas viscosity are investigated through the simulation of isothermal, low speed flow in a long straight channel using the Direct Simulation Monte Carlo (DSMC) method. Following convergence to the flow field inside the channel, the effective viscosity is calculated directly from its definition using shear stress calculat...
Conference Paper
Full-text available
The flow field in the interior of an evaporating two-dimensional sessile droplet is calculated analytically using the Stokes flow assumption and numerically using the full Navier-Stokes equation. The significance of the inertial flow terms is investigated for various Reynolds number values. Finally, a lattice Boltzmann convection-diffusion model is...
Article
Evaporation of sessile droplets gives rise to internal flow that, in turn, affects drastically the deposition of the suspended particles on the substrate. Analytical expressions for the flow field are used to compute the local velocity inside an evaporating two-dimensional droplet as a function of position and time of evaporation. Trajectories of a...
Conference Paper
Full-text available
Σε ροές αερίων σε πορώδη υλικά υπό συνθήκες υψηλής αραίωσης έχει παρατηρηθεί ότι η διαπερατότητα του μέσου δεν είναι πλέον σταθερή, αλλά μεταβάλλεται με την πίεση, σύμφωνα με το φαινόμενο Klinkenberg. Προσομοιώσεις της ροής σε πορώδη μέσα ανακατασκευασμένα με την μέθοδο της κλασματική κίνησης κατά Brown (FBM) υπό αυτές τις συνθήκες, με τεχνικές άμε...
Article
Full-text available
The effects of mixing within pore or fracture intersections on dispersion in porous media are investigated through the development and use of different simulation techniques that play particular attention to the flow field and mass transport details inside the intersection region. The flow field in an orthogonal intersection is computed using a lat...
Conference Paper
Full-text available
Στην παρούσα εργασία μελετάται η πλήρως ανεπτυγμένη ροή σε πορώδεις δομές σε συνθήκες αραίωσης χρησιμοποιώντας τις μεθόδους DSMC και δικτύου-Boltzmann με χρήση κατάλληλων συνοριακών συνθηκών. Η επίδραση της μορφολογίας του πορώδους μέσου στη ροή εξετάζεται παράλληλα με το είδος της αλληλεπίδρασης αερίου-τοιχώματος. Γίνεται μια ποσοτική παρουσίαση τ...
Article
The problem of hydrodynamic dispersion in porous media is considered and numerical predictions of the mixing degree in a single intersection are provided. The flow field in the intersection and adjacent pores or fractures is calculated using a lattice Boltzmann model for single phase flow. A particle-tracking scheme is used, subsequently, that moni...
Conference Paper
Full-text available
Ένας διαρκώς αυξανόμενος αριθμός σύγχρονων τεχνολογικών εφαρμογών, όπως ο διαχωρισμός αερίων με μεμβράνες και η εξάτμιση υμενίων υπό κενό για την παρασκευή μικροηλεκτρονικών κυκλωμάτων, χαρακτηρίζονται από φαινόμενα ροής και διάχυσης σε μεσοπόρους ή/και σε μικροπόρους, εν γένει σε χώρους με πολύ μικρές διαστάσεις και σε συνθήκες χαμηλής πίεσης. Στι...
Conference Paper
Full-text available
Τα φαινόμενα ροής και διάχυσης σε συσκευές με πολύ μικρές διαστάσεις και σε συνθήκες χαμηλής πίεσης εμφανίζονται με αυξανόμενο ρυθμό σε σύγχρονες τεχνολογικές εφαρμογές, με αντιπροσωπευτικό παράδειγμα την εξάτμιση υμενίων υπό κενό για την παρασκευή μικροηλεκτρονικών κυκλωμάτων. Στις περιπτώσεις αυτές, η μέση ελεύθερη διαδρομή των μορίων καθίσταται...
Conference Paper
Full-text available
Στην παρούσα εργασία αναπτύσσεται μια υπολογιστική μεθοδολογία πρόβλεψης του συντελεστή εγκάρσιας διασποράς σε πορώδη μέσα. Έμφαση δίνεται στην διερεύνηση των συνήθων παραδοχών ανάμειξης στις περιοχές συνάντησης των πόρων καθώς και στο εσωτερικό των πόρων. Το πεδίο ροής στο εσωτερικό μιας διασταύρωσης πόρων υπολογίζεται με την τεχνική του δικτύου-B...
Conference Paper
Full-text available
A methodology for predicting transverse dispersion coefficients in porous media is developed, using a combination of mesoscopic and molecular techniques. The dispersion process is extremely important in several applications, including soil and aquifer contamination, chemical reactors, separations, etc. In the present work, the interrelation of pore...
Conference Paper
Full-text available
Στην παρούσα εργασία αναπτύσσεται μια υπολογιστική μεθοδολογία πρόβλεψης του συντελεστή εγκάρσιας διασποράς σε πορώδη μέσα. Έμφαση δίνεται στην διερεύνηση των συνήθων παραδοχών ανάμειξης στις περιοχές συνάντησης των πόρων καθώς και στο εσωτερικό των πόρων. Το πεδίο ροής στο εσωτερικό μιας διασταύρωσης πόρων υπολογίζεται με την τεχνική του δικτύου B...
Article
A three-dimensional lattice-Boltzmann model is developed for the simulation of nonideal fluids under static and flow conditions. The van der Waals formulation of quasilocal thermodynamics for nonuniform fluids is used, and the interfacial stress tensor for nonideal fluids appears explicitly in the hydrodynamic equations. The continuity and flow equ...
Article
A two-dimensional two-phase lattice-Boltzmann model is presented and used for the study of interfacial phenomena under static and flow conditions. The model is based on the nonideal lattice-Boltzmann model proposed originally by Swift, Osborn, and Yeomans [Phys. Rev. Lett. 75, 830 (1995)] and makes it possible to couple a prescribed equation of sta...

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