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 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 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%.

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 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 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.  

scholarly journals Improving the heat transfer efficiency of a direct-flow recycling boiler using organic fluid

2021 ◽  
Vol 266 ◽  
pp. 04009
Author(s):  
M.A. Peretyatko ◽  
P.V. Yakovlev ◽  
S.A. Peretyatko
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchange ◽  
Transfer Coefficient ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Direct Flow ◽  
Heat Exchange Surface ◽  
The Heat Transfer Coefficient ◽  
Exchange Surface

This paper considers the problem of studying the heat transfer exchange during boiling in a direct-flow recycling boiler using an organic coolant. The study was conducted using numerical modelling in the ANSYS software package. Asaresultofthestudyavisual picture eofvaporphasedistributionwasobtained. This picture shows that the studied heat-exchange surface can be conditionally divided into two areas: the area of intense vaporization and the area in which the degree of dry vapor varies insignificantly. Analysis of changes in the heat transfer coefficient along the length of the heat-exchange surface led to the conclusion that heat transfer in the second area is inefficient. Based on the results of the study, it was concluded that intensification of heat transfer is necessary, for which it is proposed to install a separator at the boundary between the selected areas. The subject of the study is the dependence of the variationin the heat transfer coefficient along the length of the pipe and the determination of the boundary between the selected areas at various values of the defining parameters. Numerical simulation for therange of variationofthe defining parameters corresponding to the actual temperature regimeof power steam boilers and the conditions for the implementation of heat recovery in organic Rankine cycle unitswas performed.

scholarly journals Study heat exchange in porous structures

2022 ◽  
Vol 1216 (1) ◽  
pp. 012011
Author(s):  
A A Genbach ◽  
H I Beloev ◽  
D Yu Bondartsev ◽  
N A Genbach
Keyword(s):  
Heat Exchange ◽  
High Reliability ◽  
Thermal Power ◽  
Porous Structures ◽  
Cooling Systems ◽  
Power Plant Equipment ◽  
Heat Exchange Surface ◽  
Plant Equipment ◽  
Heat Loads ◽  
Exchange Surface

Abstract This paper shows the problem with heat exchange depending on units of thermal power plant equipment. The type of structures is determined and the heat flow for different pressures is proposed. Studies are developed for the condition of the heat exchange surface. Devices with porous coatings eliminate the development of cracks in the components and units of TPP equipment have been suggested. The research is applicable to gas turbine units of TPP. Comparable capillary-porous and flow systems have high reliability, but the former allowed the reduction of coolant consumption dozens up to 80 times. The results show that at higher heat loads it is suitable to use in porous surfaces to control the cooling surface. Evaluation of capillary-porous structures has shown their advantages over traditional cooling systems.

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.

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