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The separation of technical oils plant mechanical impurities in the electric field


Author: LEU Vasile
Degree:doctor of engineering
Speciality: 05.14.01 - General power engineering, power systems
Year:2018
Scientific adviser: Mircea Bologa
doctor habilitat, professor, Institute of Applied Physics of the
Institution: Institute of Applied Physics of the

Status

The thesis was presented on the 7 September, 2018
Approved by NCAA on the 23 November, 2018

Abstract

Adobe PDF document – 1.44 Mb / in romanian

Thesis

CZU 665:37.014

Adobe PDF document 3.67 Mb / in romanian
140 pages

Keywords

dielectric liquid, heterogeneous environment, closed phase, dispersed phase, electric field, separation of phases, electrical filtration, electric current, the dispersed phase concentration, mass transfer, potential, perforation

Summary

Thesis structure: The papers comprises an introduction, four chapters, conclusions, recommendations and future research directions, 154 bibliography sources, 15 tables and 42 figures. The results are published in 25 scientific works.

The field of study: transfer processes of mass and of heat. Purpose of work: elaboration of adequate theoretical model for engineering calculation of the filters for the dielectric liquids; confirmation of the theoretical model through experimental researches; practical implementation of the achieved experimental results by patenting of experimental samples - which were obtained with the participation of author.

Objectives of the paper: formulation of the problem and of the main research questions; elaboration of experimental samples of electrical filters and their research; selecting of the most effective and optimal filter; generalization of the experimental data; creation of mathematical model for the engineering calculation of the electrical filters; general conclusions and recommendations.

Scientific novelty and originality: method application of electric field; use of "emitter electrode" as "thread electrode" with relatively large diameter, but with perforated enameled insulation, who lead to a new physical mechanism, purely Coulomb,what is based on electrical discharge type "coronă", caused by perforations; collector and traps are designed to accumulate the dispersed phase - are made in the form of mazes from metal plates with floating potentials; separation theory, which takes into account the shielding effect of external electric field by layer with thickness in growing (like Stefan problem) of dispersed particles, which are deposited on the collector surface, the particles is being considered ideal dielectrical; also has took into account the electrical resistance of the mentioned layer; in the case of semiconductor particles (Cr2O3) or conductors (carbon) are introduced new concepts - phenomenon of electrical diffusion and of coefficient of electrical diffusion, was elaborated the respective theory; at the level of theoretical aspect - was determined concentration at the output from the electrical separator, as function of time, was demonstrated that this function is of relational type; experimental data were generalized the form of equations dimensionless of similarity; theoretical results are confirmed by the experimental results.

The important scientific problem which is solved: electro-hydrodynamic interactions in heterogeneous environments of suspension type, with dialectical liquid load phase and their applied aspects, which is researched and resolved under physical appearance of electro hydrodynamic interactions, conditioned by electric discharge type "coronă", because the processes happening in electric strongly inhomogeneous fields, for which are characteristic mentioned electrical discharges.

Theoretical significance and practical value: theoretical significance of the paper consists in developing a new theory of the separation process in external electrical field, on basis of which is placed the mechanism concept of the electrical discharge type "coronă"; it was established basic equation for the dispersed phase concentration at the exit of the separator like function of time; was researched the effect of the "apparent" disappearance of electrical separation process in time, were developed two hypotheses: of shielding of external field by the electrical load of stratum of dispersions, filed in collector for impurities, and second hypothesis - of increasing the electrical resistance of this layer; although both hypotheses do not contradict experimental data, later been shown that the effect of extinction of separation process, in some cases, can be explained and through asymptotic properties of the exponential function.

The practical value of the work. The value of the research work consist in that were performed the experimental researches of the electrical separation process and was drafted the mathematical model for engineering calculation for separators, the type of which we will call «сoronă»; experimental data were generalized by dimensionless equations – for all three cases of dispersed particles: dielectrics, semiconductors and conductors of electric current; results obtained can be directly used for goals of calculation and manufacturing of electrical separators.