scholarly journals Practical application of natural convective heat exchange of electrical equipment with air

2022 ◽  
Vol 2150 (1) ◽  
pp. 012003
Author(s):  
S M Gubanov
Keyword(s):  
Mathematical Model ◽  
Energy Consumption ◽  
Heat Exchange ◽  
Air Flow ◽  
Convective Heat Exchange ◽  
Electrical Equipment ◽  
Heat Fluxes ◽  
Temperature Fields ◽  
Practical Application ◽  
Mixed Modes

Abstract This paper provides the physical and mathematical model of the air flow in a volume, containing electrical equipment with the heat-generating and heat-absorbing surfaces. The model predicts the temperature fields and air flow velocities across the volume. Using the developed model, we calculate the values of heat fluxes in the vicinity of the thermostated electrical equipment for three different cases: natural convective, forced and mixed modes of the airflow. The possibility of beneficial use of natural convective air flows for the transfer of thermal energy is analyzed. The results are applied in an industrial enterprise. Energy consumption for ventilation is significantly reduced.

scholarly journals Mathematikal model of calclation parabola-cylindirical solar hot water systems of industrial enterprises

2020 ◽  
Vol 3 (9) ◽  
pp. 33-38
Author(s):  
Sulaymonov Husanboy Mannopovich
Keyword(s):  
Mathematical Model ◽  
Heat Exchange ◽  
Convective Heat ◽  
Convective Heat Exchange ◽  
Water Systems ◽  
Heat Losses ◽  
Heat Energy ◽  
Hot Water ◽  
Industrial Enterprises ◽  
Useful Heat

The article analyzes a mathematical model for calculating solar parabola cylindrical hot water systems for industrial and municipal enterprises. The formulas for determining heat losses associated with radiant and convective heat exchange, as well as useful heat energy and efficiency of solar parabola-cylindrical systems for obtaining heat for industrial purposes are given.

scholarly journals Сorrection сalculation of the heat source power during plasma-powder surfacing of the necks of stepped shafts

2019 ◽  
Vol 298 ◽  
pp. 00123
Author(s):  
G.R. Latypova ◽  
N.N. Karpenko ◽  
R.A. Latypov
Keyword(s):  
Mathematical Model ◽  
Heat Source ◽  
Heat Equation ◽  
Penetration Depth ◽  
Calculation Method ◽  
Temperature Fields ◽  
Lambert Function ◽  
Practical Application ◽  
Differential Heat ◽  
Source Power

A mathematical model is proposed for calculating temperature fields during arc surfacing of limited cylinders, eliminating the need for dimensionless parameters, when solving the differential heat equation, which facilitates the practical application of the developed calculation method. It is proposed that the penetration depth be calculated using the Lambert function. The obtained dependences make it possible to quantify the required correction of the heat source power in the process of surfacing the necks of stepped shafts.

Experimental Aero-Thermal Characterization of a Circular Jet Impinging a Plate: Influence of Impingement Flow Mach Number on Convective Heat Exchange Radial Distribution

2008 ◽  
Author(s):  
Gildas Lalizel ◽  
Christophe David ◽  
Matthieu Fe´not ◽  
Eva Dorignac
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Mach Number ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Convective Heat Exchange ◽  
Industrial Applications ◽  
Temperature Fields ◽  
Transfer Coefficients ◽  
Heat Transfers

Impingement jets are known to be efficient mechanisms for the exchange of heat between fluid and structure. They are generally used in industry for cooling, heating or drying. Several experimental and numerical studies have been realized to study convective heat transfers and/or to correlate the convective heat transfers to the wall with the unsteady flow of the jet (O’Donovan et al. [9] [10]). But these studies have been performed at low Mach number whereas higher Mach number are found in industrial applications as fan cooling processes for instance (M = 0.5 to 0.8). So, we propose to study the influence of Mach number of the impingement flow, ranging from 0.1 to 0.8, on convective heat exchange between a circular jet and a round axisymmetric plate. The aerodynamic of the fluid and the heat transfers depend on the following parameters: the D hydraulic diameter of the jet, the H distance to the wall, the Re Reynolds number of the flow, the M Mach number and the Tj temperature of the jet. The local convective heat transfer coefficients are experimentally determined by an inverse method based on a measurement of steady state temperature fields by infrared thermography (Fe´not et al. [2]) for 1 ≤ H/D ≤ 5 and 0.1 ≤ M ≤ 0.8. An experimental study of radial velocity fluctuations of the fluid in nearby wall has also been realized from hot wire anemometry. A spatial and temporal turbulent study (turbulence spectrum, integral turbulent scales, dissipation rate) allows to correlate convective heat transfer to the wall to aerodynamic phenomena.

INFLUENCE OF VAPOR AND CRYSTAL FORMATION PROCESSES ON HEAT EXCHANGE IN FILM VAPORATORS

2021 ◽  
pp. 32-40
Author(s):  
O. Koshelnik ◽  
V. Pavlova ◽  
T. Pugacheva ◽  
O. Kruglyakova ◽  
O. Dolobovska
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Energy Consumption ◽  
Heat Exchange ◽  
Solid Phase ◽  
Heat Transfer Process ◽  
Operating Conditions ◽  
Crystal Formation ◽  
Phase Content ◽  
Three Phase

Evaporators for changing the concentration of solutions have a different design, depending on the type of processed substance. Significant energy consumption in such equipment is associated with the need for removing large quantity of liquid phase. Multiple-effect evaporators are used to reduce the energy consumption of the evaporation process, but such equipment is quite expensive. Evaporators with secondary vapor heat reusing that operate in film mode can be an alternative to multi-effect evaporators. This equipment can operate efficiently across minimal temperature differences due to secondary vapor compressors. The disadvantage of this device is strict requirements for impurities in solutions. Impurities create deposits (incrustations) of various substances on the heat transfer surfaces, which worsens the operating conditions. If crystallizing solutions are used in evaporators with reusing of secondary vapor heat, then one of the ways to reduce the rate of heating surfaces incrustation is to add a solid phase to the initial solution. A mathematical model is proposed to describe the processes of heat and mass transfer during the film flow of crystallizing solutions, which are accompanied by a change in the physical characteristics of the solution and the formation of deposits. The model considers a three-phase liquid suspension with a varying phase content. Two stages of vaporization including vaporization on the surface of the liquid and on the surface of heat exchange are presented. The mathematical model involves the equations of continuity, energy and heat transfer, as well as the equations of motion of a three-phase flow with a changing phase content for both stages of vaporization, taking into account that solid phase turbulizes the flow and intensifies the heat transfer process. This mathematical model makes it possible to study the effect of the solid phase on heat transfer processes and the rate of incrustation in evaporators with reuse of secondary vapor heat.

scholarly journals Development of mathematical models of test systems as objects with lumped parameters

2020 ◽  
Vol 82 (2) ◽  
pp. 42-48
Author(s):  
D. O. Abramov ◽  
T. N. Shvetsova ◽  
D. I. Nazarenko
Keyword(s):  
Mathematical Model ◽  
Heat Exchanger ◽  
Block Diagram ◽  
Thermal Control ◽  
Test System ◽  
Heat Fluxes ◽  
Temperature Fields ◽  
Design Stage ◽  
Exchange Processes ◽  
Integral Characteristics

This paper deals with the problem of constructing a mathematical model for studying the thermal regime of a test system at the design stage. The test system is presented as a complex chemical-technological system, which includes a large number of elements, components and devices, characterized by a variety of functional and thermal relationships. The block-hierarchical method is used for designing the system under consideration. A thermal block diagram of the system has been developed, which includes six interconnected blocks: a thermostat; coolant; heat exchanger; cubic apparatus, medium in apparatus and environment. A mathematical model has been created to estimate the average temperatures in the system, which allows you to calculate the integral characteristics of heat exchange processes (the values average intake temperatures and the values surface average temperatures, average heat fluxes) taking into account the interaction between all blocks of the system. It was assumed that each element of the system under consideration can have thermal connections, both with the environment and with other elements of the system. It was assumed that the element can dissipate its own power, as well as the power supplied for thermal control of the element, which depends on its temperature. The calculation of the temperature fields of bodies and flows of heat carriers was carried out on the basis of models with concentrated parameters, with the assumption that there are no temperature gradients in all directions. The model is represented by a system of ordinary differential equations. The dependences of temperature on time change for two non-stationary modes of a thermostatic system consisting of a hollow device of cubic shape with a volume 3 m3 filled with gas and equipped with a heat exchanger are shown. The developed mathematical model allows solving the problems of temperature stabilization of the test system.

scholarly journals Mathematical model of heating system before the melting of the metal suspension upper half in the manufacture of turbine blades GTE

2021 ◽  
Vol 2131 (4) ◽  
pp. 042009
Author(s):  
R Vdovin
Keyword(s):  
Mathematical Model ◽  
Turbine Blades ◽  
Casting Process ◽  
Heating System ◽  
Heat Fluxes ◽  
Temperature Fields ◽  
Casting Plant ◽  
Blade Casting ◽  
Selection Of

Abstract The article presents the developed mathematical model of heating system before the upper half of the metal suspension melting during the technological process of manufacturing the turbine blades in a discrete-continuous casting plant. The relevance of this research is connected with the lack of reliable mathematical model that can predict the distribution of temperature fields and heat flows inside the plant, which have a direct impact on the quality of formed macro - and microstructure in the castings of turbine blades. The currently existing methods of indirect indicators’ estimation carry significant errors in the selection of optimal technological modes of the blade casting process. The developed model makes it possible to predict more accurate the distribution of temperature fields and heat fluxes in the corresponding zones of the casting plant. Thanks to this, it is possible to predict with maximum accuracy the production of blades with a given internal structure, as well as to estimate the amount of volumetric shrinkage and deformation of the casting. The developed mathematical model in production conditions will make it possible to predict casting defects in the form of captivity and failure, reduce labor capacity and increase the productivity of the blade casting process.

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