scholarly journals Deposit thickness control of the heat exchange equipment by hardware and software complex

2020 ◽  
Vol 22 (4) ◽  
pp. 106-114
Author(s):  
E. V. Garnyshova ◽  
E. V. Izmaylova ◽  
Yu. V. Vankov
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Thermal Power ◽  
Amplitude Spectrum ◽  
Signal Amplitude ◽  
Free Vibrations ◽  
Steel Plates ◽  
Energy Losses ◽  
Software Complex ◽  
Heat Exchange Equipment

The deposits formation on heat exchange surfaces is an important problem in the thermal power industry. Since the thermal conductivity coefficient of deposits has low values, even a small layer of them creates a large thermal resistance. Deposits on the heat exchange equipment surfaces reduce the heat transfer coefficient, heat transfer efficiency, and lead to significant energy losses. To restore the operation design mode, such heat exchangers must be decommissioned and contaminated surfaces must be cleaned. Energy losses can be reduced if deposits on heat exchange surfaces are detected in a timely manner. The paper discusses a method for controlling deposits thickness on heat exchange surfaces. The method is based on the damping parameters analysis of the controlled product free vibrations. The research was carried out on models of the heat exchange equipment surfaces-steel plates 400x160x2 mm, with different deposits thickness 1 During studying of the acoustic characteristics, the natural vibrations frequencies were determined tenfold with each type of plate. Signal processing occurs in a program that allows you to receive and record data from an audio device, calculate the signal amplitude spectrum in the time domain, and return it as a value and phase (receiving the frequency spectrum). The Wilcoxon rank sum was used to determine the spectrum changes dynamics. The researches have shown that the free vibrations method allows us to determine not only the presence of deposits on the heat exchange surfaces, but also their thickness.

scholarly journals TAKING INTO ACCOUNT DEPENDENCE OF VISCOSITY COEFFICIENT ON TEMPERATURE DURING VAPOR CONDENSATION ON A VERTICAL WALL

2020 ◽  
Vol 63 (5) ◽  
pp. 94-101
Author(s):  
Aleksandr I. Moshinskiy ◽  
Pavel G. Ganin ◽  
Alla V. Markova ◽  
Larisa N. Rubtsova ◽  
Vladislav V. Sorokin
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchange ◽  
Transfer Coefficient ◽  
Dynamic Viscosity ◽  
Viscosity Coefficient ◽  
Vapor Condensation ◽  
Condensation Temperature ◽  
Heat Exchange Equipment ◽  
The Heat Transfer Coefficient

In the present study, the problem of vapor condensation on a flat vertical surface is investigated in the case of an arbitrary dependence of the dynamic viscosity coefficient on temperature according to a fairly general law. At a constant value of this coefficient and other characteristics of a condensing liquid (heat conductivity coefficient, density) this task was considered by Nusselt in a constant gravitational field. The results obtained by Nusselt formed the basis (with certain modifications) for the computational practice of heat exchange equipment of chemical technology in the presence of steam condensation of any heat carrier. Formation of a condensate film occurs due to heat transfer through the liquid film, vapor condensation at the outer edge of the film and the flow of liquid along the surface. The article generalizes the Nusselt theory for the heat transfer coefficient under the indicated conditions, and as a result, convenient calculation formulas for the heat transfer coefficient, which are necessary to describe the operation of heat and mass exchange equipment. Approximate relations are proposed for calculating the dynamic viscosity coefficient, which are useful for calculating film flow on a flat surface. A comparison is made with the previously used ratios in an approximate manner taking into account the dependence of viscosity coefficient on temperature. When in technical applications one wants to determine the average value of two parameters, which are then used to calculate certain characteristics of a process, then, traditionally, the average of these parameters is considered. This article shows that by simplifying the dependence of the effective dynamic viscosity coefficient, more accurate results are obtained by dividing the interval of the width of the current film in the ratio of three to one, where three fourths refer to the wall temperature, and one fourth to the condensation temperature. The analytical dependencies presented in this paper can be used for practical calculations of the heat exchange equipment.

scholarly journals NOVEL TRENDS OF DEVELOPMENT AND PERFECTION THE MODERN HEAT EXCHANGERS

2019 ◽  
pp. 54-65
Author(s):  
B.S. Soroka
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Exchange Process ◽  
Combustion Products ◽  
Reynolds Analogy ◽  
Heat Exchange Equipment ◽  
Heat Exchange Process ◽  
Heat Transfer Phenomenon ◽  
Relative Change

Some actual aspects of advancement the problem of improvement the heat exchange equipment are considered in the paper. First of all the actual items related to middle and high temperature recuperators are discussed with proper up-to — date approaches. The classification of flue gases heat recovery appliances has been proposed along with the statement and analysis of the main characteristics of the recovery plants and option the ways of optimization the mentioned characteristics. The problem of Reynolds analogy (similarity of relative change the heat transfer phenomenon and variation the hydraulic resistance) within the channels of different purpose and of various cross-section supplied with and without the obstacles has been analyzed in application to separate cases of flow along the surfaces equipped with the cavities (dimples) or the convex elements. Thermal Performance Factor (TPF) of the heat exchange process is qualitatively like to Reynolds analogy factor and is highly depended upon rate of heat transfer and of friction factor in conditions of the scheme under consideration for flow over the surface or flow within the channel. The various media has been compared used as a working body in the heat exchanger’s channels: gaseous, liquid and the nanofluids, the last appeared in practice since 2000. Analysis has been carried out on effect of using the secondary energy emitters (SEE) arranged inside the tube channels, on resulting heat flux by heat exchange between outward flow of combustion products and the inner air flow. Bibl. 23, Fig. 6.

scholarly journals INTENSIFIED PLATE HEAT EXCHANGE DEVICE IN HEAT SUPPLY SYSTEMS OF THE HOUSING AND COMMUNAL SERVICES OF THE RUSSIAN FEDERATION

2021 ◽  
pp. 53-62
Author(s):  
L. A. Kushchev ◽  
V. A. Uvarov ◽  
N. Yu. Savvin ◽  
S. V. Chuikin
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Exchange ◽  
Laboratory Tests ◽  
Plate Heat Exchanger ◽  
Plate Heat ◽  
Exchange Processes ◽  
Intensification Of Heat Exchange ◽  
Heat Exchange Equipment ◽  
The Heat Transfer Coefficient

Statement of the problem. The problem of intensification of heat exchange processes in a plate heat exchanger on the basis of the HH№ 02 heat exchanger of the Ridan company is discussed. It is essential to carry out an analysis of the existing methods of intensification of heat exchange processes in plate devices according to the results of the analysis to choose the most promising method of intensification of heat exchange process and based on it to develop a patent-protected design of a heat exchange plate. Laboratory tests of the intensified plate heat exchanger with increased turbulence of the coolant are performed. The results of thermal tests on a specialized laboratory installation of the resulting and the serial heat exchanger are presented.Results. The results of the comparison of experimental studies of the intensified plate heat exchanger with the increased turbulence of the heat carrier and the serial plate heat exchanger of identical heat power are shown. The graphs of dependence of the heat transfer coefficient, which is the major characteristic of the operation of heat exchange equipment, on the average temperature pressure are designed. Conclusions. As a result of the laboratory tests in the specialized laboratory of BSTU named after V. G. Shukhov and research at the Voronezh State Technical University established a rise in the heat transfer coefficient due to the increased turbulence of the coolant flow, which causes a decrease in metal consumption and reduces the cost of heat exchange equipment.

scholarly journals Experimental Investigation of Thermal and Hydraulic Characteristics of Finned Flat Tubes of the Oil Air Cooling Device

2020 ◽  
Vol 63 (2) ◽  
pp. 138-150 ◽  
Author(s):  
S. V. Tiunov ◽  
A. N. Skrypnik ◽  
G. S. Marshalova ◽  
V. M. Gureev ◽  
I. A. Popov ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Thermal Power ◽  
Experimental Studies ◽  
Performance Criteria ◽  
Maximum Height ◽  
Air Cooling ◽  
Cooling Device ◽  
Transfer Resistance ◽  
Cooling Devices

Air cooling devices are heat exchange units that are widely used in practice. However, they have a number of disadvantages due to the low value of the heat transfer coefficient from the air and the high resistance of finned tube bundles, which leads to large dimensions and the metal content of the device itself, to the need to develop a high power ventilator drive, but also to the need to demonstrate reduced energy efficiency. The objective of the present work is to determine optimal geometric sizes of finned flat heat exchange tubes manufactured by the techniques of extrusion and deforming cutting that reduce the weight and size characteristics of the heat exchange section of air cooling devices. The experimental studies of seven various samples of heat exchange sections, being different in fin pitch and height, tube section width, flat tube height and a number of inner channels, have determined the performance of each section with the use of the following criteria: thermal power, thermal efficiency, specific thermal heat transfer resistance, M. V. Kirpichev and V. M. Antuf’ev’s criteria. The obtained experimental data and the analysis of the passive method of enhancement in the near-wall area of the heat transfer surface finned by deforming cutting has shown that sample No 5 has maximum value of the performance criteria when the maximum height of a fin is 0.008 m and the minimum pitch of a fin is 0.0025 m over the investigated sample range. Thus, when the sizes of an oil air cooling device are maintained by using the amended heat transfer section of sample No 5, the amount of removed heat can be increased or the mass and dimensions of the device can be decreased while maintaining thermal power and, as a result, the power consumption for pumping can be decreased and the thermal-hydraulic performance of the device as a whole can be increased.

scholarly journals Experimental efficiency evaluation of the of various geometry twisted bands for heat transfer intensification in the heat-exchange channels of a nuclear power unit equipment

2021 ◽  
Vol 2088 (1) ◽  
pp. 012046
Author(s):  
A E Sobornov ◽  
S M Dmitriev ◽  
R R Ryazapov ◽  
A V Mamaev ◽  
A V Kotin
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Pressure Drop ◽  
Nuclear Power ◽  
Efficiency Evaluation ◽  
Heat Transfer Intensification ◽  
Operating Modes ◽  
Optimal Geometry ◽  
Nuclear Power Unit ◽  
Heat Exchange Equipment

Abstract The paper is devoted to experimental study of heat exchange and pressure drop of channel with various geometry twisted bands. The studies were carried out in the range of operating modes parameters of the nuclear power units’ heat exchange equipment. The three different designs of intensifiers are presented in the paper. The values of heat transfer coefficient and pressure drop are obtained. The dependences of the Nusselt number (Nu) on the Reynolds number (Re) were calculated. The comparative analysis of intensifiers is made. The efficiency factor was also calculated on experimental data. The most optimal geometry form of intensifier was selected.

scholarly journals Optimization of the built-in recuperator surface of recuperative burner according to the criterion of energy coefficient maximum

Vestnik IGEU ◽  
2020 ◽  
pp. 5-11
Author(s):  
A.B. Biryukov ◽  
A.N. Lebedev ◽  
P.A. Gnitiev ◽  
Ya.S. Vlasov
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchange ◽  
Transfer Coefficient ◽  
Fuel Consumption ◽  
Thermal Power ◽  
Aerodynamic Resistance ◽  
Combustion Products ◽  
Energy Coefficient ◽  
The Heat Transfer Coefficient

The recuperative burners is a modern direction of reducing fuel consumption during the heat treatment of metals in furnaces. Their use can significantly reduce fuel consumption. Despite the evident advantages, the spread of such equipment is constrained due to its high cost. The research is conducted for determining ribs rational profile and optimizing mass and size characteristics of a built-in recuperator. There are results that make it possible to reduce either the recuperator mass or its aerodynamic resistance. However, such changes contradict each other, so a compromise solution must be found. Currently, there are no generally accepted methods of thermotechnical calculations for recuperative burners. This work aims to develop a methodology to optimize the built-in recuperator surface according to the criterion of maximizing the energy coefficient. To conduct the study, the elements of recuperative heat exchange theory for counter-flow media were used. The proven methodology for determining the temperature of heated air and cooled combustion products after recuperator was applied. Also, the known concept of energy coefficient was used for the research. A technique has been developed to optimize the surface of the incorporated heat exchanger according to the criterion of maximizing the energy coefficient. The technique includes composing an expression for determining the energy coefficient, taking its derivative and equating it to zero with further solving the obtained equation with respect to heat exchange surface. The developed method was used in the recuperative burner with the thermal power of 500 kW. For the range of heat transfer coefficient 75–200 W/(m2·K) associated to the smoothtube part, a fifth-degree polynomial has been determined which describes the dependence of the smoothtube part optimal value of a built-in recuperator surface on the heat transfer coefficient. The developed technique is important for recuperative burners design, for increasing their efficiency and reducing their production cost. The methodology error associated with the assumption that the heat transfer coefficient is constant when the length of the built-in recuperator changes does not exceed 5 %.

scholarly journals Use of new similarities Bl and Blturb. to optimize the calculation and selection of heat exchange equipment for working with nanofluid coolants

2021 ◽  
Vol 23 (96) ◽  
pp. 46-53
Author(s):  
Y. Bilonoga ◽  
V. Stybel ◽  
O. Maksysko ◽  
U. Drachuk
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Heat Exchangers ◽  
Seed Oil ◽  
Surface Forces ◽  
Express Method ◽  
Pumpkin Seed ◽  
Heat Exchange Equipment ◽  
Pumpkin Seed Oil ◽  
Selection Of

The problem of correct, exact calculation and selection of the optimal heat exchange equipment at use in it of nanoliquid heat carriers was investigated in the work. Classical numerical equations, which are widely used in the calculation and selection of heat exchangers with nanofluids, especially at temperatures above 50 °C, give an error of (15–20) % or more. This leads to the fact that the selected heat exchange equipment may not work efficiently with excessive consumption of thermal energy. A new approach to heat transfer processes is considered, taking into account the theory of J. Businesque, which gives an idea of turbulent viscosity and thermal conductivity, as well as comparing the resistance of the coolant flow to the nanoparticle with surface forces and considering turbulent fluid as Newtonian. It is shown that the consideration of the behavior of a nanoparticle in a turbulent liquid coolant without taking into account surface forces is inaccurate and erroneous. The physical content of the previously obtained new numbers of similarity Bl and Blturb is considered and the possibility of their effective application in the new numerical equation obtained by us for the calculation of heat exchangers using nanofluid coolants is shown. The existing express method of estimating the efficiency of nanorluids use in heat exchangers on the basis of classical numerical equations is analyzed and a new express method on the basis of a new numerical equation and new numbers of similarity Bl and Blturb is proposed. The proposed express calculation method shows that a mixture of H2O + EG (60:40) improves the heat transfer properties of water by + 12.86 %, and a mixture of (H2O + EG (60:40) + 1.5 % TiO2) and (milk) + 0.5 % pumpkin seed oil) – by +16.75 %, which corresponds to the experiments and our calculations, and the known express method based on classical numerical equations shows a deterioration of – 4.5 % and, accordingly, by – 1.2 %. An example of calculating the optimal shell-and-tube heat exchanger according to the new algorithm when heating milk with hot water with the addition of mixtures (H2O + EG (60:40) + 1.5 % TiO2) and accordingly (milk + 0.5 % pumpkin seed oil) fully confirms the correctness of the new express –method.

Intensified Plate Heat Exchange Device in Heat Supply Systems of the Housing and Communal Services of the Russian Federation

2021 ◽  
pp. 60-69
Author(s):  
Л. А. Кущев ◽  
В. А. Уваров ◽  
Н. Ю. Саввин ◽  
С. В. Чуйкин
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Exchange ◽  
Laboratory Tests ◽  
Plate Heat Exchanger ◽  
Plate Heat ◽  
Exchange Processes ◽  
Intensification Of Heat Exchange ◽  
Heat Exchange Equipment ◽  
The Heat Transfer Coefficient

Постановка задачи. Рассматривается задача интенсификации теплообменных процессов в пластинчатом теплообменном аппарате на базе теплообменника НН№ 02 фирмы Ridan . Необходимо выполнить анализ существующих методов интенсификации теплообменных процессов в пластинчатых аппаратах, по результатам анализа выбрать наиболее перспективный метод интенсификации процесса теплообмена и на его основе разработать патентозащищенную конструкцию теплообменной пластины. Выполнить лабораторные испытания интенсифицированного пластинчатого теплообменного аппарата с повышенной турбулизацией теплоносителя. Сравнить результаты теплотехнических испытаний на специализированной лабораторной установке разработанного теплообменника и серийного. Результаты. Приведены результаты сравнения экспериментальных исследований интенсифицированного пластинчатого теплообменного аппарата с повышенной турбулизацией теплоносителя и серийного пластинчатого теплообменника одинаковой тепловой мощности. Построены графики зависимости коэффициента теплопередачи, являющегося основной характеристикой работы теплообменного оборудования, от среднего температурного напора. Выводы. В результате лабораторных испытаний в специализированной лаборатории БГТУ им. В. Г. Шухова и исследований в Воронежском государственном техническом университете установлен прирост коэффициента теплопередачи за счет повышенной турбулизации потока теплоносителя, что приводит к снижению металлоемкости и уменьшению стоимости теплообменного оборудования. Statement of the problem. The problem of intensification of heat exchange processes in a plate heat exchanger on the basis of the HH№ 02 heat exchanger of the Ridan company is discussed. It is essential to carry out an analysis of the existing methods of intensification of heat exchange processes in plate devices according to the results of the analysis to choose the most promising method of intensification of heat exchange process and based on it to develop a patent-protected design of a heat exchange plate. Laboratory tests of the intensified plate heat exchanger with increased turbulence of the coolant are performed. The results of thermal tests on a specialized laboratory installation of the resulting and the serial heat exchanger are presented. Results. The results of the comparison of experimental studies of the intensified plate heat exchanger with the increased turbulence of the heat carrier and the serial plate heat exchanger of identical heat power are shown. The graphs of dependence of the heat transfer coefficient, which is the major characteristic of the operation of heat exchange equipment, on the average temperature pressure are designed. Conclusions. As a result of the laboratory tests in the specialized laboratory of BSTU named after V. G. Shukhov and research at the Voronezh State Technical University established a rise in the heat transfer coefficient due to the increased turbulence of the coolant flow, which causes a decrease in metal consumption and reduces the cost of heat exchange equipment.

scholarly journals Application of porous materials in heat exchangers of heat supply system

2020 ◽  
Vol 22 (3) ◽  
pp. 3-13
Author(s):  
N. V. Rydalina ◽  
B. G. Aksenov ◽  
O. A. Stepanov ◽  
E. O. Antonova
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Mathematical Model ◽  
Heat Exchanger ◽  
Heat Exchange ◽  
Porous Materials ◽  
Heat Exchangers ◽  
Porous Metals ◽  
Porous Aluminum ◽  
Heat Exchange Equipment

Heat exchange capacity increase is one of the main concerns in the process of manufacturing modern heat exchange equipment. Constructing heat exchangers with porous metals is an advanced technique of heat exchange increase. A construction of heat exchangers with porous aluminum is described in this paper. The first heat transfer agent (hot water) flows through thin copper tubes installed within the porous aluminum. The second heat transfer agent (freon) flows through the pores of aluminum. Laboratory facility was created to study such a heat exchanger. Series of experiments were carried out. The purpose of the research presented here is to create a mathematical model of heat exchangers with porous metals, to perform analytical calculation of the heat exchangers and to confirm the results with the experimental data. In this case, one can`t use the standard methods of heat exchangers calculation because the pores inner surface area is indeterminate. The developed mathematical model is based on the equation describing the process of cooling the porous plate. A special mathematical technique is used to take into account the effect of tubes with water. The model is approximate but its solution is analytic. It is convenient. One can differentiate it or integrate it, which is very important. Comparison of calculated and experimental data is performed. Divergence of results is within the limits of experimental error. If freon volatilizes inside the heat exchanger, the heat of phase transition has to be taken into account alongside with heat capacity. The structure of the mathematical model makes it possible. The results presented in this paper prove the practicability of using porous materials in heat exchange equipment.

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