Vol 52, No 3-4 (2016)

A mathematical model of bubble-induced mixing of organic substrate in a biogas generating bioreactor is developed. The model describes motion of a two-phase medium consisting of liquid phase–biomass and disperse phase–bubbling gas under turbulent operating conditions. The model is based on equations in both general dimensionless and criterial form, which allows its use for designing and calculating bubble reactors of various capacities.

The possibility of mixing foaming liquids in a centrifugal field is investigated. A theoretical analysis of the formation of foam showed that under certain design and operational parameters of the cylindrical continuous-flow hydrocyclone the process of mixing foaming media can take place without foaming.

A vibrowave generator for vibroimpact on bottom-hole formation zone (BFZ) and restoration of well production is developed to solve the problems of pollution and reduction of BFZ permeability.

The results of experimental research on hydrodynamics of solution flow in membrane channel are reported. Response curves correlating flow pattern with solution flow rate, pressure, and type of membrane module are obtained. A theoretical analysis of the research results is made with a description of the response curves using criterial equations that correlate empirical coefficients with solution flow rate in the channel, pressure, and type of membrane elements.

The article presents the scientific rationale for the approach to the development of an adaptive management system for the electric discharge machining process based on artificial intelligence principles to achieve the required surface quality of the workpiece. A three-layer neural network for controlling the process of electric discharge machining and a block diagram of the research bench to study the efficiency of electric discharge machining with the use of the developed adaptive control system are described.

The physicochemical properties of activated carbons (AC) were investigated in order to determine their basic characteristics that define the absorption capacity of activated carbons with different absorbates (coolants). The absorption capacities of the working pairs AC–ammonia, AC–methylamine, and AC–ethylamine were investigated. Specific parametric coefficients for the Dubinin–Radushkevich structural equation were obtained. The experimental dependence of the daily cycle of solar-powered thermotransformers working with the pair AC–ammonia was presented and proved the positive effect of the work. The thermodynamic efficiencies of solar-powered thermotransformers with the working pairs were determined from the exergy coefficients and suggested areas for efficient application of solar-powered thermotransformers.

Features in the process of modeling the vectors of the input and output variables of petroleum recovery process control systems with different degrees of detail of their structures are considered. Methods of monitoring discharges of liquids at perforated depth intervals of water injection and petroleum producing wells of oil and gas deposits as the basic condition for implementing a real-time regime in these systems are proposed. Conditions for increasing the precision with which the parameters of the variables are monitored based on the hardware components employed in measurements of complex borehole media are considered.

In this work, a new liquid cooling system for a piston compressor based on pressure fluctuations of discharged gas is described. The developed method of calculation based on the fundamental laws of conservation of motion, mass, and energy recorded for gas and coolant is implemented in the form of a package of applied programs for the calculation of the cooling system of a single-stage piston compressor.

The results of study of a piston hybrid machine that combines the function of a positive displacement pumpcum-compressor unit are reported. A distinctive feature of the studied machine is the presence between the piston and the cylinder wall of a slot seal made in the form of a hydrodiode. A numerical model of the motion of an incompressible viscous liquid in the channel of the hydrodiode made in 3D axisymmetric formulation is proposed. The turbulence effects are determined using SST (shear-stress transport) model. It is shown that the rate of liquid flow through the slot seal depends on the direction of motion. The physical nature of this phenomenon is analyzed.

This article is the second stage of the research on annular slot hydrodiode. Computational experiments were conducted to establish the correlation between the response functions of the hydrodiode and a number of geometric and hydraulic factors. The results are presented in the form of regression equations, which are used to optimize the geometry of the hydrodiode flow section with a view to minimizing the ratio of the rates of liquid flow through the hydrodiode in forward and reverse directions. The physical phenomena accompanying the hydrodiode operation are analyzed in detail.

Analysis of operation of electrostatic precipitators at high concentrations of the fine dispersed phase is given here. Changes in the parameters of the electrostatic precipitator in the presence of the dispersed phase are considered. Theoretical analysis of the process of corona discharge locking is given. Calculation results of electric field voltage distribution in the presence of a charged dispersed phase and the distribution of aerosol concentration over the cross section of the electrode gap are given. The expediency of using discharge electrodes with a low corona discharge ignition voltage is demonstrated.

The resistance of steels with different carbon contents to sulfide stress corrosion cracking arising as a result of the joint effect of chlorides and sulfides contained in seawater is discussed. It is shown that corrosion cracking tests for samples under uniaxial tension at a constant strain rate can be used for accelerated testing. Parameters recommended in different regulations for assessment of steel resistance to stress corrosion cracking are compared. It is shown that the specific work of steel fracturing is an indicator reflecting most comprehensively the change in steel strength and plastic characteristics.

Monitoring of the operation of grinding of the end faces of parts used in the petrochemical industrial by means of digital photography and topograms of the end faces with the use of a comparatively simple method is proposed. A new numerical quality indicator that describes the relief of macro-irregularities is introduced for this purpose. The technique has been approved for grinding of corrosion-resistant steels by Aerobor wheels. Reasons for the occurrence of a pseudo-regular relief on a surface are established. A relationship between the kinematics of grinding and the variation in the bearing surface area is demonstrated by means of statistical analysis. Recommended fields of effective application of the results of the study are given.

A new hybrid energy-converting piston machine with gas plenum in the suction is proposed. A computation technique based on the laws of conservation of energy, mass, and motion and the equation of state, written for a gas and a cooling liquid, is developed. The computation technique is implemented in the form of computer programs for use in calculating the working processes of a piston machine.