A numerical study of heat transfer and hydrodynamics in plate heat exchangers with corrugated fins was carried out. The effect of corrugation pitch on heat flow and pressure drop was studied. The study was carried out using computational fluid dynamics in the ANSYS software package (v. 19.2). The results of the study showed that increasing the corrugation pitch from n = 5 to n = 9 leads to an increase in heat flow of 10.83% and a pressure drop of 28.30%.

Keywords: plate-fin heat exchanger, corrugated fins, heat transfer, hydrodynamics, numerical study, calculation, heat flow, pressure drop, energy efficiency, cooling system

A numerical simulation was used to investigate heat transfer in plate-fin radiators with round fillet profiles of various depths, including 0.55 mm, 1.1 mm, and 1.5 mm. The issue of flowing air around a radiator with a mass flow rate of 10-3 to 4·10-3 кг/с and a temperature of 293 K was solved. The radiator was heated using a heater, whose temperature was set from 323 to 353 K. Changes in heat flow, pressure drop, and energy efficiency indicator were shown depending on the air mass flow, according to the calculation results. The research findings indicate that the radiator featuring round fillet profiles and a depth of 1.65 mm exhibits the highest heat flow and energy efficiency indicators, as well as the lowest pressure drop.

Keywords: radiator, cooling system, numerical modeling, computational fluid dynamics, heat transfer, heat flow, pressure drop, energy efficiency, calculation, electronics

Using numerical simulation, particle deposition in a porous heat exchanger was studied; the mechanism of sediment formation was sinvestigated, and the influence of sediment on the heat flow was assessed. The influence of porous heat exchanger length, dust particle size, and air flow velocity on particle deposition efficiency, particle breakthrough, and heat flux value was studied. Research results have shown that with increasing length of the heat exchanger, the efficiency of dust particle deposition increases, which leads to the formation of sediment. In turn, the sediment reduces the value of the heat flow from the porous heat exchanger. Depending on the length of the heat exchanger and air velocity, the reduction in heat flow is 3.43-7.27%.

Keywords: porous media, heat exchanger, particle deposition, deposition efficiency, particle breakthrough, sediment, heat flow, numerical modeling, computational fluid dynamics, calculation

Using numerical simulation, we carried out studies on the effect of the length of a porous heat exchanger on the deposition of dust particles. The heat exchanger models with lengths of 5, 10, 20 and 30 mm were the subject of the studies. At the boundaries of the computational domain, we set the air velocity at 0.1, 1, and 5 m/s and the diameter of dust particles from 10-7 to 10-4 m. Research results have shown that with increasing length of the porous heat exchanger, the efficiency of dust particle deposition increases. This can lead to a decrease in the thermal and hydraulic characteristics of the heat exchanger.

Keywords: porous media, heat exchanger, numerical simulation, calculation, deposition of dust particles, heat exchanger length, air flow velocity, particle diameter, air cooling, microelectronics

The article considers the cramped conditions of urban development, its types and main problems, during construction work. The organization of monolithic works at the construction site is also presented.

Keywords: monolithic works, constrained construction conditions, constriction, organization of monolithic works, concreting, construction site, monolithic framework, building compaction, problems of constriction, organization of construction, point development

The article presents the local type of logistic centers in urban environment as an essential part of freight network and its place in hierarchic logistic system of a country. Transport, compositional, ecologic and other aspects that have impact on spacial concept of local logistic centers are under examination. Thus generalized models of local logistic centers are put forward. They are developed by the authors with large volume of handled cargo, turnover capacity, and are space-saving. The main concepts of such models are following:  vertical development of storage volume due to construction of several floor and shelf storage levels with different ramps as well as provision of comfort one-way transport of minimum maneuvers and without crossing and conflicting traffic.

Keywords: architectural spatial concepts, logistic centers, warehousing types , generalized spacial model

In the article a double-gap cavity with anti-phase excitation that has wide application in designs of floating-drift klystrons is considered. One of the ways of reduction of time during machine design of klystron’s cavity is using of the simple analytical expression, allowing to determine the main klystron electrodynamic parameters with a sufficient accuracy for practice. In the article we presented the results of physical and mathematical modeling of the double-gap cavity, the corrected mathematical models were introduced that can be utilized in programs of a prompt optimization of klystron's type devices. The technique of creation of approximate mathematical model in this case was reduced to definition of basic analytical function, and the subsequent approximation between experimental and calculated data by means of a method of planned experiment. In presented work the analysis of adequacy was carry out. Analysis revealed inaccuracy of a resonance frequency of an anti-phase type in chosen ranges of change of influencing factors doesn’t exceed 1%, characteristic impedance- 5%. The received analytical ratios allow carrying out quickly calculation of parameters of the cavity, without labor-consuming and expensive experiments and calculations.

Keywords: double-gap cavity, electrodynamic parameters, mathematical simulation, resonance frequency, characteristic impedance, method of planned experiment

In the article are considered the results of the researches of noncorrodibility of the concrete received with the use of industrial wastes and mineral-chemical additives of various structures in various combinations. Research has shown increase of noncorrodibility, durability and water resistance of the concrete obtained with the use of additives, and the most effective, at that, is the sharing of mineral-chemical additives.

Keywords: concrete, mineral-chemical additives, industrial wastes, noncorrodibility, decstrin, lignosulfonat, kinetic, durability

The main maintenance of a diversification of production as activity of subjects of managing is considered. being shown in purchase of the operating enterprises, the organizations of the new enterprises, redistribution of investments in interests of the organization and development of new production on available floor spaces. The most important organizational economic targets of a diversification of management are presented by innovative activity of the industrial enterprise.

Keywords: Герметичный компрессор объемного действия, система охлаждения, холодопроизводительность, перегрев, холодильный коэффициент COP, энергоэффективность.

`Described is the methodology of studying of topology of tensor quantity of magnetic field of leakage of natural defects in the natural geomagnetic field magnetization, which is the base for realization of digital Hall defect scope. Using this set it was managed to register the defects with the peculiar size of 15 microns in steel wire, which is used for reeling of butter spring of trucks.

Keywords: non-destructive testing, Hall-effect sensor, magnetic tomography.

The technology and the equipment providing clearing of the wood areas, their preparation for restoration of the wood of works and preparation of stubs and roots for use in bio-energetic are considered.

Keywords: biological fuel, roots, korchevka, stubs, cutting, equipment, technology, power wood.

Information about authors of issue №4 (2011)

Keywords: authors