scholarly journals Determination of the sediment thickness on the heat-exchange surfaces by free vibration method

2019 ◽  
Vol 124 ◽  
pp. 05069
Author(s):  
E.V. Izmaylova ◽  
E.V. Garnyishova ◽  
R.B. Kazakov ◽  
V.V. Serov
Keyword(s):  
Heat Exchange ◽  
Free Vibration ◽  
Heat Exchangers ◽  
Steel Plates ◽  
Sediment Thickness ◽  
Vibration Method ◽  
Heat Exchange Equipment ◽  
The Heat Transfer Coefficient ◽  
Heat Exchange Efficiency

Sediments on the heat exchangers surfaces reduce the heat transfer coefficient and heat exchange efficiency, and lead to significant energy losses. The paper discusses the method of express control of the sediment thickness on heat-exchange surfaces. The method is based on the analysis of attenuation of free oscillations parameters of the controlled product. Studies were conducted on models of the heat-exchange equipment surface, namely steel plates of 400 mm long, 160 mm wide and 2 mm thick, with different sediments thicknesses of 0, 1.0, 1.5, 2.0, 2.5 mm. The Wilcoxon’s rank sum test was used to determine the dynamics of the spectra changes. Studies have shown that the free vibration method allows one to determine not only the presence of deposits on the heat-exchange surfaces, but also their thicknesses.

scholarly journals POLYMERS AND PLASTIC USE FOR THE HEAT-EXCHANGE EQUIPMENT (REVIEW)

2020 ◽  
pp. 59-71
Author(s):  
I.O. Mikulionok
Keyword(s):  
Heat Exchange ◽  
Heat Exchangers ◽  
Polymeric Materials ◽  
Strength Properties ◽  
Polymers And Plastics ◽  
Heat Exchange Equipment ◽  
Coefficient Of Heat Conductivity ◽  
Exchange Apparatus ◽  
Polymer Type

The possibility of use of the heat-exchangers in whole or in part manufactured with use of polymers and plastics is considered. Despite obvious, at first sight, inexpediency of use of polymeric materials in the heat-exchange equipment (low coefficient of heat conductivity, and also low, in comparison with metals, the strength properties of the majority of the most widespread polymers), «polymeric» heat-exchangers find application in various areas of the industry more and more surely. Classification of heat-exchange apparatuses which constructive elements are executed with use of polymeric materials is proposed. The following signs are the basis for classification: polymer type, a type of polymer meric material, type of the heat-exchange apparatus (a form of heat-exchange elements), reliance on polymeric materials in apparatuses, motion freedom of polymeric heat-exchange elements, level of assembly of a design, and also diameter of tubular elements. Critical analysis the most characteristic designs developed by domestic and foreign designers and inventors is carried out. Ref. 21, Fig. 13.

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 Computational parametric study on efficiency of low boiling point fluid plants under heat exchange process intensification

2021 ◽  
Vol 289 ◽  
pp. 06003
Author(s):  
Alena Likhaeva ◽  
Sergey Grigoriev ◽  
Evgeniy Trushin ◽  
Marat Dasaev
Keyword(s):  
Heat Exchange ◽  
Parametric Study ◽  
Boiling Point ◽  
Heat Exchangers ◽  
Exchange Process ◽  
Electricity Consumption ◽  
Process Intensification ◽  
Exchange Processes ◽  
Heat Exchange Equipment ◽  
Heat Exchange Process

One of the main challenges for the energy industry is to improve the reliability and efficiency of heat exchange equipment in heating plants. Phase-change heat exchangers with low boiling point fluid (LBPF) are widely used in both conventional and renewable energy. The main objectives of increasing the efficiency of heat exchange equipment are to reduce the weight and dimensions, to increase the amount of heat transferred and to reduce the electricity consumption spent on pumping the heat transfer agent. These objectives are achieved by implementing various methods of heat exchange intensification in heat exchange equipment. A key aspect concerning application of various types of heat exchange intensifiers in heat exchange equipment is evaluation of possibility to increase their design efficiency. The paper presents the results of a computational parametric study of changes in efficiency of some LBPF-based plants when intensifying heat exchange processes by modifying functional surfaces of heat exchangers by laser ablation.

scholarly journals Features of creation and use of effective heat exchangers

2020 ◽  
Vol 216 ◽  
pp. 01124
Author(s):  
Shavkat Agzamov ◽  
Sevinar Nematova
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Heat Exchange ◽  
Prandtl Number ◽  
Flow Rate ◽  
Heat Exchangers ◽  
Heat Transfer Equation ◽  
The Heat Transfer Coefficient ◽  
Outside Diameter

The article discusses the features of the creation and use of efficient heat exchanger. Designs of pipes with a developed heat exchange is presented. The procedure for determining the degree of development of the heat exchanging surface, the heat transfer coefficient, and the calculation of the heat transfer equation are given. As a result of creating efficient heat exchangers, three main parameters are used: the pipe outside diameter; the estimated flow rate; the Prandtl number.

scholarly journals Research possibility of application of non-destructive testing method based on the Barkhausen effect for the control of heat exchange equipment, exposed to im-pulse pressure

2019 ◽  
Vol 114 ◽  
pp. 06011
Author(s):  
V.V. Potapov ◽  
M.V. Lopatin ◽  
L.I. Lopatina ◽  
L.M. Chebotnyagin
Keyword(s):  
Heat Exchange ◽  
Heat Exchangers ◽  
Control Method ◽  
Non Destructive Testing ◽  
Barkhausen Effect ◽  
Destructive Testing ◽  
Testing Method ◽  
Heat Exchange Equipment ◽  
Reliability Of Operation ◽  
Non Destructive

The article deals with the issues of ensuring the reliability of operation and methods for evaluation of connections (tube attachment points in tube sheets) of heat exchangers used in various industries. It is estimated the applicability of the control method based on the Barkhausen effect to check the place of tube fastening in tube sheets. Installations are considered as heat exchangers in which the connection is derive pipe with tube sheets is obtained by using impulsed pressure sources.

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 DEVELOPMENT OF HIGH EFFICIENT SHELL-AND-TUBE HEAT EXCHANGERS BASED ON PROFILED TUBES

2020 ◽  
Author(s):  
Djamalutdin Chalaev ◽  
◽  
Nina Silnyagina ◽  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Heat Exchange ◽  
Transfer Coefficient ◽  
Hydraulic Resistance ◽  
Heat Exchangers ◽  
Experimental Studies ◽  
Corrugated Tube ◽  
The Heat Transfer Coefficient

The use of advanced heat transfer surfaces (corrugated tubes of various modifications) is an effective way to intensify the heat transfer and improve the hydraulic characteristics of tubular heat exchangers. The methods for evaluating the use of such surfaces as working elements in tubular heat exchangers have not been developed so far. The thermal and hydrodynamic processes occurring in the tubes with the developed surfaces were studied to evaluate the efficiency of heat exchange therein. Thin-walled corrugated flexible stainless steel tubes of various modifications were used in experimental studies. The researches were carried out on a laboratory stand, which was designed as a heat exchanger type "tube in tube" with a corrugated inner tube. The stand was equipped with sensors to measure the thermal hydraulic flow conditions. The comparative analysis of operation modes of the heat exchanger with a corrugated inner tube of various modifications and the heat exchanger with a smooth inner tube was performed according to the obtained data. Materials and methods. A convective component of the heat transfer coefficient of corrugated tube increased significantly at identical flow conditions comparing with a smooth tube. Increasing the heat transfer coefficient was in the range of 2.0 to 2.6, and increased with increasing Reynolds number. The increase in heat transfer of specified range outstripped the gain of hydraulic resistance caused by increase of the flow. Results and discussion. CFD model in the software ANSYS CFX 14.5 was adapted to estimate the effect of the tube geometry on the intensity of the heat transfer process. A two-dimensional axially symmetric computer model was used for the calculation. The model is based on Reynolds equation (Navier-Stokes equations for turbulent flow), the continuity equation and the energy equation supplemented by the conditions of uniqueness. SST-turbulence model was used for the solution of the equations. The problem was solved in the conjugate formulation, which allowed assessing the efficiency of heat exchange, depending on various parameters (coolant temperature, coolant velocity, pressure). The criteria dependences were obtained Nu = f (Re, Pr). Conclusions. The use a corrugated tube as a working element in tubular heat exchangers can improve the heat transfer coefficient of 2.0 - 2.6 times, with an increase in hydraulic resistance in the heat exchanger of 2 times (compared with the use of smooth tubes). The criteria dependences obtained on the basis of experimental studies and mathematical modeling allow developing a methodology for engineering calculations for the design of new efficient heat exchangers with corrugated tubes.

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.

Simulation of Tube-to-Support Dynamic Interaction in Heat Exchange Equipment

1989 ◽  
Vol 111 (4) ◽  
pp. 378-384 ◽  
Author(s):  
N. J. Fisher ◽  
M. J. Olesen ◽  
R. J. Rogers ◽  
P. L. Ko
Keyword(s):  
Heat Exchange ◽  
Heat Exchangers ◽  
Room Temperature ◽  
Analytical Techniques ◽  
Dynamic Interaction ◽  
Fretting Wear ◽  
Flow Induced Vibration ◽  
Support Plate ◽  
Heat Exchange Equipment ◽  
Good Agreement

Tubes within tube and shell heat exchange components are supported at intermediate points by support plates. Flow-induced vibration of a tube can cause it to impact or rub against a support plate or against adjacent tubes and can result in tube fretting-wear. The tube-to-support dynamic interaction is used to relate experimental wear data from test rigs to real multi-span heat exchanger configurations. Analytical techniques are required to estimate this interaction in real heat exchangers. Simulation results from the VIBIC code are in good agreement with three examples from the open literature and are in reasonable agreement with measurements from the CRNL single-span room temperature fretting-wear rigs. Therefore, the VIBIC code is a good analytical tool for estimating tube-to-support dynamic interaction in real heat exchangers.

scholarly journals Research of variable characteristics of heat exchange equipment

2019 ◽  
Vol 114 ◽  
pp. 07001
Author(s):  
Tatyana Rafalskaya ◽  
Valery Rudyak
Keyword(s):  
Heat Exchanger ◽  
Heat Exchange ◽  
Heat Exchangers ◽  
Variable Parameter ◽  
Simulation Method ◽  
Operating Modes ◽  
Mode Of Operation ◽  
Heat Exchange Equipment ◽  
Large Systems ◽  
Simulation Results

Heat exchangers used in various industries, most often work in conditions of variable flows and temperatures. At the same time, the existing theories of calculation of heat exchanger modes are based on the use of constant dimensionless parameters in any mode of operation. The purpose of this work is to obtain dependencies to determine the effect of coolant temperatures on the variable parameter of the heat exchanger. Using the simulation method, dependencies were found that describe the change in the heat exchanger parameter which made it possible to obtain a general formula for the change in the heat exchanger parameter at varying coolant temperatures. To test the applicability of the existing relations describing the change in the heat exchanger parameter and the formula obtained, a large number of heat exchangers were calculated in variable operating modes. Comparison with the simulation results showed that the ratios of the known theories of heat exchangers do not work in all modes and their application can lead to significant errors. A formula has been obtained allows one to find the effect of coolant temperatures on the variable parameter of the heat exchanger. The formula can be used to predict the modes of large systems.

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