D.G. Avraam

D.G. Avraam
Region of Central Macedonia, Regional Unity of Imathia · Department of Environment and Hydroeconomy

Chemical Engineer, PhD

About

43
Publications
9,288
Reads
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1,377
Citations
Additional affiliations
September 2004 - March 2015
Technological Educational Institute of Western Macedonia
Position
  • Senior Researcher
Description
  • Fundamental and applied research on enhanced and environmental liquid fuels and energy resources
September 2004 - June 2012
Technological Educational Institute of Western Macedonia
Position
  • Research Assistant
Description
  • Technology of Measurements
September 2003 - June 2004
Technological Educational Institute of Western Macedonia
Position
  • Research Assistant
Description
  • Fluid Mechanics and Hydraulics
Education
December 1988 - October 1996
University of Patras
Field of study
  • Chemical Engineering
September 1983 - November 1988
University of Patras
Field of study
  • Chenical Engineering
September 1980 - June 1983
2nd Lyceum in Veria
Field of study

Publications

Publications (43)
Article
Full-text available
Steady-state two-phase flow in porous media was studied experimentally, using a model pore network of the chamber-and-throat type, etched in glass. Optical observations and macroscopic measurements were used to determine the flow regimes, and to calculate the corresponding relative permeabilities and fractional flow values. The relative permeabilit...
Article
Full-text available
A steady-state model for trickle-bed reactors was developed, primarily concerning hydroprocessing of light oil feedstocks containing volatile compounds. The case of a homogeneous plug flow fixed bed reactor with axial dispersion was considered. Catalyst particles were assumed to be isothermal and isoconcentrational. Mass balances, overall two-phase...
Article
Full-text available
An experimental and theoretical study for the biogas steam reforming reaction over 5%Ru/Al2O3 catalyst have been performed. An apparatus was constructed for the conduction of the experiments, the core of which was a tube reactor, filled with the catalyst in form of pellets. The inlet gas mixture consisted of CH4 and CO2 in various composition ratio...
Article
Catalysts with active phase Ni, Co or Cu supported on γ- alumina were synthesized at constant loading (8 wt. %) and tested for the glycerol steam reforming reaction (GSR). The synthesized samples, at their calcined and/or their reduced form, were characterized by BET, ICP, XRD, DRS, NH3-TPD, CO2-TPD, TPR and SEM. The carbon deposited on their surfa...
Article
Full-text available
For the work presented herein nickel catalysts supported on γ-alumina extrudates (Ni/Al) with an egg-shell structure were prepared, using a modified Equilibrium Deposition Filtration (EDF) technique. Their performance was compared, for the biogas dry reforming reaction, with corresponding Ni/Al catalysts with a uniform structure, synthesized via th...
Conference Paper
Full-text available
νικελίου (8% κ.β.) στηριζόμενων σε υπόστρωμα αλουμίνας (Ni/γ-Al2O3 και Ni/4% La2O3-Al2O3), στην διεργασία της υδρογονο-αποξυγόνωσης του φοινικέλαιου (palm oil), χρησιμοποιώντας τη μέθοδο του υγρού εμποτισμού. Συγκεκριμένα, μελετήθηκε η επίδραση της θερμοκρασίας, της πίεσης και της ταχύτητας χώρου (LHSV) στη συνολική μετατροπή του λαδιού, στην απόδο...
Conference Paper
Full-text available
The increase in biodiesel production has resulted in an oversupply of glycerol, which is the main byproduct (10 wt. %); thus, its utilization is fast becoming an economic, as well as, an environmental necessity. In the present work, a comparative study of Ni (8 wt. %) catalysts supported on commercially available Al2O3 and AlCeO3 carriers was under...
Conference Paper
Full-text available
Η αντίδραση της ξηρής αναμόρφωσης του βιοαερίου έχει ως στόχο την παραγωγή υδρογόνου ή/και αερίου σύνθεσης. Περιλαμβάνει την απομάκρυνση, μέσω της μετατροπής τους, αερίων του θερμοκηπίου που περιέχουν άνθρακα, δηλαδή CH4 και CO2, δημιουργώντας παράλληλα προϊόντα προστιθέμενης αξίας [1,2]. Το οξείδιο του αργιλίου ή αλουμίνα (Al2O3) χρησιμοποιείται ε...
Conference Paper
Full-text available
Στην παρούσα εργασία, παρουσιάζεται μια προσπάθεια λεπτομερούς μοντελοποίησης και τεχνικοοικονομικής βελτιστοποίησης της βασικής μονάδας αναμόρφωσης γλυκερόλης με ατμό, ενός αντιδραστήρα σταθερής καταλυτικής κλίνης. Η μοντελοποίηση και βελτιστοποίηση εστιάστηκε σε έναν αντιδραστήρα μικρής βιομηχανικής κλίμακας (παραγωγής υδρογόνου ισοδύναμης με την...
Conference Paper
Full-text available
Ο εμποτισμός πορωδών φορέων μεγάλης ειδικής επιφάνειας από υγρά διαλύματα ενεργών μετάλλων, στη μορφή μεταλλικών αλάτων ή συμπλόκων, αποτελεί μια σημαντική διεργασία για την παρασκευή των περισσοτέρων ετερογενών καταλυτών. Αντικείμενο της παρούσης εργασίας είναι η περιγραφή της εξέλιξης της μακροκατανομής (αξονικής βαθμίδας συγκέντρωσης) του ενεργο...
Conference Paper
Full-text available
Ο εμποτισμός πορωδών φορέων μεγάλης ειδικής επιφάνειας από υγρά διαλύματα ενεργών μετάλλων, στη μορφή μεταλλικών αλάτων ή συμπλόκων, αποτελεί μια σημαντική διεργασία για την παρασκευή των περισσοτέρων ετερογενών καταλυτών. Κατά τη διεργασία του υγρού εμποτισμού (wet impregnation), ο υδατοδιαβρεκτός (water wet) φορέας έρχεται σε επαφή με το διαβρέχω...
Conference Paper
Full-text available
Steady-state two-phase flow experiments are performed on a sand column equipped with two differential pressure transducers and six ring electrodes to measure the pressure drop across each phase, and the electrical resistance across five successive segments of the column. The electrical resistance is converted to water saturation by Archie equation....
Article
Full-text available
A fast and accurate technique based on multipoint electrical measurements is used to monitor the hydrocarbon mobilization and solubilization in a porous medium during the rate-controlled injection of a surfactant solution. The residual n-decane (n-C10) remaining in a soil column after one cycle of n-decane/ NaCl solution drainage-imbibition is flus...
Conference Paper
Full-text available
The experimentally measured water and oil relative permeability curves of 2-D and 3-D water-wet model porous media are interpreted in terms of multi-parameter functions of water saturation and oil and water capillary number. Depending on the porous medium type and prevailing flow parameters, the oil and water relative permeability may be strong, mo...
Conference Paper
Full-text available
In the last years, an important research effort is being carried out in the development of solid catalysts active in the valorisation of glycerol. However, the effort in this reaction is much more dispersed, since it is faced to the great variety of potential routes for glycerol valorisation. It is known that in cases of biodiesel production via he...
Conference Paper
Full-text available
A fast and accurate method, based on multipoint electrical measurements, is used to monitor the hydrocarbon mobilization/dissolution in a porous medium, during the rate-controlled injection of a surfactant solution. The residual n-C 10 remaining in a soil column after a fast drainage and a slow imbibition step is flushed by an aqueous solution of N...
Article
Full-text available
The water krw and oil kro relative permeability curves of a glass-etched planar pore network are estimated with history matching from transient displacement experiments performed at varying values of the capillary number, Ca, for two fluid systems: one of intermediate and one of strong wettability. The transient krw,kro are compared to correspondin...
Conference Paper
Full-text available
The relative permeability, rw k , ro k , and capillary pressure, c P , curves, are estimated with history matching from transient displacement experiments performed on a model porous medium, at varying values of the capillary number, Ca , for two fluid systems: one of intermediate and one of strong wettability. The transient rw k , ro k are compare...
Article
Full-text available
For the macroscopic prediction of non-Newtonian NAPL migration in highly heterogeneous fractured formations, information is required about the capillary pressure and relative permeability functions of single fractures. In the present work, non-Darcian models are developed to describe the single-phase flow and immiscible displacement of non-Newtonia...
Article
Full-text available
The conventional wet-chemistry techniques used for the fabrication of porous media models exhibit some shortcomings with regard to the control of the structural parameters of pores etched either on glass or on plastic plates. A new method of fabrication of pore network micro-models, using an excimer laser LIGA technique, is presented. First, the mi...
Article
Full-text available
The pore-scale flow mechanisms and the relative permeabilities during steady-state two-phase flow in a glass model pore network were studied experimentally for the case of strong wettability (θe < 10°). The capillary number, the fluid flow rate ratio, and the viscosity ratio were changed systematically, while all other parameters were kept constant...
Chapter
Full-text available
Concepts of percolation theory, universal scaling laws, thin film flow and fractal geometry are used to develop realistic expressions for the capillary pressure and relative permeability curves for the case of two-phase (oil/water) flow in natural porous media (e.g. sedimentary rocks, soils, etc.). Approximate analytical expressions are derived for...
Article
Full-text available
Concepts of percolation theory, universal scaling laws, thin film flow and fractal geometry are used to develop realistic expressions for the capillary pressure and relative permeability curves for the case of two-phase (oil/water) flow in natural porous media (e.g. sedimentary rocks, soils, etc.). Approximate analytical expressions are derived for...
Article
Full-text available
The role of the oil/water viscosity ratio kappa and the wettability (expressed as equilibrium contact angle theta(eq)) during forced imbibition in a nonplanar (two-layer) porous medium is investigated experimentally. The results show that kappa and theta(eq) act in combination not only for intermediate and large capillary numbers, but also for smal...
Article
Full-text available
A highly miniaturized cell for the experimental investigation of thin foam and emulsion films has been constructed. The miniaturization of the structure in the new design is achieved by forming the cell out of thin glass slides drilled by excimer laser and sintered into a single structure. The capillary pressures and film dimensions attainable in o...
Article
Full-text available
A parametric experimental investigation of the coupling effects during steady-state two-phase flow in porous media was carried out using a large model pore network of the chamber-and-throat type, etched in glass. The wetting phase saturation,S 1, the capillary number,Ca, and the viscosity ratio,k, were changed systematically, whereas the wettabilit...
Article
Full-text available
A comparative experimental study of steady-state two-phase flow in two types of model porous media is made to determine the effects of nonplanarity on the flow mechanisms and the mesoscopic flow behavior. The two model porous media have virtually the same pore geometry, but one has a planar network skeleton, whereas the other has a nonplanar (two-l...
Article
Full-text available
The role of the viscosity ratio κ during forced imbibition in porous media is investigated theoretically using a new simulator, and experimentally based on displacements in model pore networks. Both theory and experiment show that κ is an important parameter of microdisplacement in porous media, not only for intermediate and large capillary number...

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Projects

Projects (5)
Archived project
Biogas steam reforming for hydrogen production
Archived project
Modelling of Catalyst Preparation by Impregnation Methods