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Optimization of mixers with bars with intermittent action and processes of mixing in construction

Author: Lozan Alexandr
Degree:doctor of engineering
Speciality: 05.02.13 - Machines and equipment (according to branches)
Scientific adviser: Sergiu Andrievschi
doctor, associate professor (docent), Technical University of Moldova
Institution: Technical University of Moldova


The thesis was presented on the 28 April, 2017
Approved by NCAA on the 31 May, 2017


Adobe PDF document1.72 Mb / in romanian


CZU 693.542.5.(043.2)

Adobe PDF document 12.02 Mb / in romanian
181 pages


mixer, bar, intermittent, mixture, homogenization, intensification, optimization, stream, concrete, mortar, optimization, planning


The doctoral thesis includes an introduction, four chapters (119 text pages, 55 drawings, 20 tables), general conclusions, bibliography (128 sources) and 27 annexes.

Based on the obtained results 12 scientific articles are written and published in journals, collections of national and international conferences, five patents are obtained.

The purpose of the work consists in optimize of constructive and technological parameters of mixer with bars and intermittent action, that will ensure obtaining homogeneity of the mixture and high productivity with minimum energy consumption.

In the paper the theoretical bases of the mixing process is elaborated and expanded, and the influence of constructive and technological parameters on the resistance to mixing, the homogeneity of the mixture and productivity of mixers with bars and with intermittent action is determined.

The research was performed using statistical methods, the theory of probability, and the theory of planning of multifactor experiment. New methods and stands for performing the multifactor experiments are developed, mathematical models that adequate describe the process of mixing in the mixers with bars and intermittent action are obtained.

New constructive solutions of mixers with bars and with intermittent action, are developed, searched and proposed, namely: longitudinal scraper with elastic element; articulated radial and longitudinal scraper; equipped with stiffening rings mixing organs; bar located with shift on the shaft surface; gravitational mixing. These solutions ensure: exclusion of particles blocking in the mixing process; reduction resistance to mixing, metal consumption and weight mixers; increasing the potential energy of the mixture components.

The research results of the influence the constructive and technological parameters on the mixing process in the form of second-degree polynomials, nomograms useful for designing and operating of the mixers are proposed.

The equation for determining of the resistance to mixing in the mixers with bars and with intermittent action depending on the seven constructive and technological factors are proposed, namely: the filling coefficient of the drum; particle size; diameter of the bars; diameter of the drum; humidity of the mixture; the length of the drum; angle of entry of bars in the mixture. Based in the formula was built engineering nomogram, which makes it possible to quickly determine the optimal parameters of the mixer and mixing process, which ensures the lower resistance to mixing.