scholarly journals Low-Reynolds Simulation of Heat Transfer in Turbulent Flow in a Flat Channel with Symmetrically Arranged Turbulators on Both Sides of the Channel

2020 ◽  
Vol 4 (1) ◽  
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Cross Section ◽  
Heat Exchangers ◽  
Thermal Loading ◽  
Flat Channel ◽  
Heat Transfer Intensification ◽  
Heat Flows ◽  
Heat Exchange Surface ◽  
Exchange Surface

Widespread use in modern heat exchangers and apparatus received heat exchangers, where the channels have a cross-section, different from the round tubes, in a particular case, flat channels, where heat is not produced by means of a full surface to be washed. The thermal loading of a flat channel can be asymmetric, since the heat flows on different surfaces can be unequal, namely: flat channels with one-way heating or with two-way heating with unequal heat flows. In order to ensure the compactness of heat exchange devices and heat exchange apparatuses, heat transfer intensification is used, which in flat channels is achievable by two main methods: the development of the heat exchange surface and turbulence of the flow in the channels.

scholarly journals CONSTRUCTIVE DESIGN OF HEAT EXCHANGERS "TUBE-IN-TUBE" (REVIEW)

2020 ◽  
pp. 63-74
Author(s):  
I.O. Mikulionok
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Heat Exchangers ◽  
Critical Analysis ◽  
Vortex Generators ◽  
Small Surface ◽  
Heat Exchange Surface ◽  
Main Defect ◽  
Exchange Surface

Advanced designs of one of the simplest and reliable heat-exchange apparatuses for processing of various liquid and gaseous environments – heat exchangers "tube-in-tube" are considered. New designs in the majority a case eliminate the main defect of classical heat exchangers "tube-in-tube" – a small surface of a heat transfer. However increase in a heat exchange surface usually significantly complicates production and/or operation (including repair) heat exchangers. Classification of the heat exchange devices "tube-in-tube" is proposed: The following signs are the basis for classification: assembly level, quantity of streams in channels, the design material nature, degree of mobility of heat exchange tubes, existence of vortex generators in channels, a form of external and/or internal tubes. The critical analysis of the most characteristic designs of the heat exchangers "tube-in-tube" developed by domestic and foreign designers and inventors is made. Bibl. 17, Fig. 21.

scholarly journals FEATURES OF CALCULATION OF ON-BOARD HEAT EXCHANGERS

2021 ◽  
pp. 52-59
Author(s):  
U. L. Moshentsev ◽  
А. А. Gogorenko
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Heat Exchangers ◽  
Cooling System ◽  
Transfer Coefficients ◽  
Design Problems ◽  
Average Value ◽  
Heat Transfer Coefficients ◽  
Heat Exchange Surface ◽  
Exchange Surface

Aspects of designing an onboard heat exchangers for the cooling system of the ship's power plant are considered. Such heat exchangers must be designed in accordance with the classical foundations of the theory and calculation of heat exchangers. At the same time, the key design points are considered by well-known sources in a separate setting related to the peculiarities of their consideration as specific elements of the theory. In this regard, they are not united by a single system necessary for their use in specific design problems. Accordingly, the paper highlights, concretizes and refines the parameters of the formulas used in the computational problem. In particular, the calculation of the heat transfer coefficient from the seawater side is performed according to the formula that gives the average value of the coefficient for the vessel. The heat transfer coefficients from the side of the coolant of the inner loop are calculated according to the well-known formulas recommended for calculating heat transfer in channels of any shape. Attention is drawn to the fact that heat transfer from the hold side goes to the finned wall. In this regard, the heat transfer coefficients determined by the indicated formulas should be considered convective. The transition to the given values of the heat transfer coefficients should be carried out considering the efficiency of the finned heat exchange surface, which considers the uneven temperature of various sections of the heat exchange surface. The calculation of heat transfer was carried out considering possible surface contamination. The procedure for performing the calculation steps is proposed, as a result of which the dimensions and heat engineering parameters of the heat exchanger can be determined. It was found that the use of the considered proposals leads to results close to those recommended by authoritative sources. The above proposals do not contradict the experience of creating and designing such structures. The recommendations can be used for educational and practical purposes by those who design heat exchangers of similar designs.

scholarly journals About mathematical modeling of aerodynamic characteristics in devices with a leakage of the impact systems of plane-parallel streams on the heat exchange surface

2018 ◽  
Vol 170 ◽  
pp. 03024
Author(s):  
Larisa Haritonova ◽  
Valery Azarov ◽  
Igor Stefanenko
Keyword(s):  
Heat Exchange ◽  
Heat Exchangers ◽  
Aerodynamic Resistance ◽  
Aerodynamic Characteristics ◽  
Plane Parallel ◽  
Heat Exchange Surface ◽  
Parallel Streams ◽  
The Impact ◽  
The Mathematical Model ◽  
Exchange Surface

The article is devoted to the development of the general aerodynamic theory in case of a leakage by the systems of plane-parallel impact jets on the plane heat exchange surface [1-2]. An analytical generalization of data on aerodynamic resistance with the blowout of flat surface by the system of the plane-parallel impact jets was implemented. These data were obtained as a result of the application of mathematical theory of planning an experiment. The equations of regression are the mathematical model of process. Functional dependences between the constructive factors and the regime parameters of these first obtained experimental dependences on aerodynamic resistance in the jet heat exchangers with the leakage of air in the form of the system of plane-parallel jets were established. Results of work can be used in developing of different methods of calculation for various new designs of highly effective heat exchangers or their optimization for various branches.

Mathematical Models of the Ocurved Spring Tubes Surfaces

2019 ◽  
Vol 16 (11) ◽  
pp. 4554-4559 ◽  
Author(s):  
Valeriya Leonidovna Vorontsova ◽  
Alfiya Gizzetdinovna Bagoutdinova ◽  
Almaz Fernandovich Gilemzianov
Keyword(s):  
Heat Exchange ◽  
Mathematical Models ◽  
Heat Exchangers ◽  
Coil Spring ◽  
Compact Heat Exchangers ◽  
Curved Channels ◽  
Exchange Processes ◽  
Heat Exchange Surface ◽  
The Creation ◽  
Exchange Surface

One of the ways to intensify heat exchange processes is the creation of compact heat exchangers with a developed heat exchange surface. It is known that coil-type channels provide a developed heat exchange surface and belong to one of the most efficient and technological designs of heat exchange elements. In this regard, the authors proposed a small-size heat exchanger of the “pipe in pipe” type with an internal coil spring-twisted channel, and the authors of the proposed article developed mathematical models describing the heat-exchange surfaces of pipes of complex configurations, including coil spring-coiled channels. The equations of heat transfer surfaces are written in vector-parametric form based on the fundamental principles of analytical and differential geometry. In order to verify the adequacy and visualization of the written equations, surfaces were constructed using the Matlab application software package. The proposed mathematical models can be used in computer simulation of hydrodynamic processes during the flow of liquid media in curved channels, which will allow to explore and further optimize their internal geometry by changing the parameters of the equations. This work is a continuation of research on the creation of efficient heat exchangers.

scholarly journals THE STUDY OF HEAT TRANSFER IN INTENSIFIED SHELL AND TUBE DEVICE

2019 ◽  
Vol 4 (4) ◽  
pp. 77-82
Author(s):  
Н. Никулин ◽  
Nikolay Nikulin
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchange ◽  
Transfer Coefficient ◽  
Heat Exchange Surface ◽  
Shell And Tube ◽  
Heated Fluid ◽  
Supply Systems ◽  
The Heat Transfer Coefficient ◽  
Exchange Surface

The use and prevalence of heat exchangers in Russian heat supply systems are considered. Attention is paid to the improvement of serial heat exchangers with smooth tubes – the increasing of heat transfer coefficient. One of the ways to increase the heat transfer coefficient is considered: it is the turbuliza-tion of the fluid flow on the heat exchange surface. The original design of the heat exchange surface for shell and tube devices of heat supply systems is presented. The dynamics of the heated fluid in the annular space of a shell and tube heat exchanger when flowing around the heat exchange surface with a modified geometry is studied (RF Patent 149737). A feature of the dynamics is a circular edge (element of the surface of heat exchange), which contributes to the creation of turbulence in the flow of the heated liquid on the plate and on the surface of the next edge. Emphasis is placed on heat ex-change processes between the solid surface of the edges and the heated fluid. For a circular cross sec-tion, the equation of thermal conductivity in cylindrical coordinates is compiled, taking into account the stationary heat exchange process, with an internal source of thermal energy. Solution of equation makes possible to determine the change in temperature on the surface and the average temperature of the edge. This value allows determining the Prandtl number to calculate the heat transfer coefficient.

scholarly journals Heat transfer in laser passive and deformable mirrors

2021 ◽  
Vol 2088 (1) ◽  
pp. 012042
Author(s):  
E Leonov ◽  
A Chernykh ◽  
Yu Shanin
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Deformable Mirrors ◽  
Optical Surface ◽  
Optical Elements ◽  
Cooling Systems ◽  
Highly Efficient ◽  
Heat Exchange Surface ◽  
Exchange Surface

Abstract In work, the possibilities of using uncooled and cooled optical elements (including laser passive and deformable mirrors) with an increase in the power of laser facilities are analyzed. To increase the permissible light loads acting on the optical elements, the use of highly efficient cooling systems with minichannels (coplanar and multi-tiered), providing a high compactness of the heat exchange surface and the intensification of heat transfer, is considered. The advantages and efficiency of the proposed cooling systems for reducing the displacement of the optical surface of the mirror due to bending are estimated.

scholarly journals EXPERIMENTAL STUDIES OF THERMAL TRANSMISSION THROUGH A MOBILE HEAT EXCHANGE SURFACE

2020 ◽  
Vol 2018 (1) ◽  
pp. 28-31
Author(s):  
Borislav Kustov ◽  
Mihail Gerasimchuk
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Exchange ◽  
Flow Rate ◽  
Experimental Studies ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Heat Exchange Surface ◽  
Thermal Transmission ◽  
Exchange Surface

Experimental studies of heat transfer in a heat exchanger of the "pipe-in-pipe" type with a rotating tube have been performed. It is established that in the investigated range of hot coolant flow rate, the rotation of the pipe makes it possible to increase the values of the heat transfer coefficients by 19-28%.

Optimization of geometric parameters and analysis of exergy efficiency of heat recovery units glass furnaces

2021 ◽  
pp. 5-17
Author(s):  
N. Fialko ◽  
◽  
A. Stepanova ◽  
R. Navrodska ◽  
S. Shevchuk ◽  
...  
Keyword(s):  
Heat Exchange ◽  
Heat Exchangers ◽  
Heat Recovery ◽  
Glass Melting ◽  
Exergy Efficiency ◽  
Geometric Parameters ◽  
Hot Water ◽  
Air Heating ◽  
Heat Exchange Surface ◽  
Exchange Surface

The paper presents the results of optimization of the geometric parameters of the heat exchange surface of water and air-heating heat exchangers of glass-making furnaces and an analysis of their exergy efficiency. Ensuring the efficient operation of heat recovery units in various thermal circuits is an urgent problem of heat power engineering. The aim of the work is to establish the optimal areas of the geometric parameters of the heat exchange surface of heat recovery units of glass-melting furnaces and to analyze their exergy efficiency. The paper presents the results of solving the tasks necessary to achieve the goal: - using statistical methods for planning the experiment, determine the levels of variation of the parameters of the geometric surface of heat transfer for the heat recovery units under study and calculate the values of the criteria for evaluating the efficiency at the points of the central orthogonal compositional plan; - to obtain the regression equations for the investigated heat exchangers, to determine the optimal areas of change in the geometric parameters of the heat exchange surface and the corresponding exergy efficiency criteria. To determine the optimal areas of geometric parameters of the heat exchange surface, a complex methodology is used based on the methods of exergy analysis and statistical methods of the theory of experiment planning. It has been established that when designing heat recovery schemes for heating water in heat supply systems and for heating blast air, heat recovery units with the following values of the areas of variation of the geometric parameters of the heat exchange surface can be used: - the values of the area of variation of the distance between the panels for heat recovery units with a staggered and corridor arrangement of pipes in a bundle s1 = 58.0-62.0 mm. - the values of the areas of change in the diameter of pipes for a hot water heat exchanger with a corridor arrangement of pipes d = 41.0-43.0 mm and for an air heating heat exchanger with a staggered and corridor arrangement of pipes d = 29.0-31.0 mm. - the use of the values of the ranges of change of other parameters is carried out taking into account additional technological factors. It has been established that the exergy efficiency of hot water heat recovery units is in all cases higher than the exergy efficiency of air heating units. For hot water heat exchangers, the values of exergy criteria are lower than for air heating ones: k – 2.0 times, ε – by 7.5%, m0 – 1.9 times. The expediency of using the investigated heat recovery units in heat recovery circuits of glass melting furnaces has been established, taking into account the results obtained and in the presence of certain technological factors. The results obtained and further developments in the field of optimization of the operating parameters of heat recovery units for glass-melting furnaces will provide an increase in the efficiency of heat recovery equipment for power plants.

Summary of heat transfer processes and their comparative evaluation for capillary porous coatings in power plants

2019 ◽  
Vol 12 (1) ◽  
pp. 29-35
Author(s):  
A. A. Genbach ◽  
D. Yu. Bondartsev ◽  
A. Y. Shelginsky
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Power Plants ◽  
Cooling System ◽  
Heat Pipes ◽  
High Heat ◽  
Porous Structures ◽  
Heat Exchange Surface ◽  
Exchange Surface ◽  
Thin Fi Lm

The crisis of heat exchange at boiling of water in porous structures used for cooling of heat-stressed surfaces of various aggregates is investigated. The study refers to thermal power installations of power plants. The experiments were carried out on a stand with heat supply from an electric heater. Cooling of heat-exchange surfaces was performed by water supply to porous structures with diff erent cell sizes. It is shown that in porous cooling systems of elements of heat and power plants processes of fl uid boiling take place, and at high heat fl ows it is possible to approach a crisis situation with overheating of the heat-exchange surface. The heat exchange processes are described, the infl uence of thermophysical properties of heat exchange surface is shown, and optimal sizes of porous structure cells are determined. A calculated equation is obtained for determining the critical heat fl ux at high pressures. The calculation of the critical load with respect to the examined porous structures was carried out with taking into account the underheating and fl ow rate, from which it follows that the underheating of the liquid enables to expand slightly the heat transfer capabilities in a porous cooling system. The experimental data of the investigated capillary porous cooling system operating under the joint action of capillary and mass forces are generalized, and its characteristics q=f(ΔT) are compared with boiling in large volume, heat pipes and thin-fi lm evaporators. The limits of diff erent capillary-porous coatings are given. High heat transfer boosting is provided by combined action of capillary and mass forces and has advantages in comparison with boiling in large volume, thin-fi lm evaporators and heat pipes. It is shown that the results of theoretical calculations conform well with experimental data.

scholarly journals USING OF TUBULAR HEAT EXCHANGE SURFACE WITH DIMPLES IN THE GAS TURBINE REGENERATORS

2017 ◽  
Vol 39 (5) ◽  
pp. 70-77
Author(s):  
A. A. Khalatov ◽  
G. V. Kovalenko ◽  
A. J. Meyris
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Gas Turbine ◽  
Hydraulic Resistance ◽  
Tubes And Pipes ◽  
Heat Exchange Surface ◽  
Smooth Tubes ◽  
Turbine Capacity ◽  
Exchange Surface

Comparison of heat transfer and hydraulic resistance of bundles of smooth tubes and pipes with the surface formed by dimples. Calculations performed for the gas turbine capacity of 16 MW allows minimizing the mass of the regenerator.  

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