Conjugate heat transfer in a closed volume with the local heat sources and non-uniform heat dissipation on the boundaries of heat conducting walls

Is solved the problem of heat transfer in the closed volume, limited by heat-conducting walls, with the local source of heat emission and the heterogeneous conditions of heat sink on the outer boundaries of solution area. The problem of convective heat transfer is solved with using a system of differential Navier-Stokes equations in the Boussinesq approximation. The simulation of turbulent flow conditions of heated air is carried out within the framework to k-ε model. On the basis the analysis of the obtained temperature field and the contour lines of stream functions is made conclusion about the essential transiency of the process in question. The obtained values of temperatures and speeds in different sections of region illustrate turbulence of the process. Are investigated laws governing the formation of temperature fields in closed areas with a local heat emission source under the conditions of intensive local heat sink into environment and accumulation of heat in the enclosing constructions

Analysis of influence of heat insulation on the thermal regime of storage tanks with liquefied natural gas

Is numerically investigated the process of convective heat transfer in the reservoirs of liquefied natural gas (LNG). The regimes of natural convection in a closed rectangular region with different intensity of heat exchange at the external borders are investigated. Is solved the time-dependent system of energy and Navier-Stokes equations in the dimensionless variables “vorticity – the stream function”. Are obtained distributions of the hydrodynamic parameters and temperatures, that characterize basic regularities of the processes. The special features of the formation of circulation flows are isolated and the analysis of the temperature distribution in the solution region is carried out. Is shown the influence of geometric characteristics and intensity of heat exchange on the outer boundaries of reservoir on the temperature field in the LNG storage

Influence of heatsink from upper boundary on the industrial premises thermal conditions at gas infrared emitter operation

The results of mathematical simulation of the heat transfer processes in the closed domain, which corresponds to production accomodation with the gas infrared emitter operation condition are presented. The system of differential Navier-Stokes equations in the approximation of Boussinesq is solved. The comparative analysis of thermal conditions formation in the closed domain is carried out taking into account heat withdrawal through the upper enclosing construction and under the conditions of its heat insulation. The essential transiency of the analyzed heat transfer process and the influence of heat withdrawal from one of the outer boundaries on the mean temperatures values in large-dimension industrial premises are established

Influence of strouhal number on the temperature fields in the locked space with the working source of the radiant heating

Is carried out a numerical study of the heat transfer process in the closed domain with the source of radiant heating. Is solved the system of differential equations in the dimensionless setting, which describes free convection in the airspace and thermal conductivities in the enclosing constructions. Examined the influence of the dimensionless parameter, which characterizes the unsteady motion of liquids or gases (Strouhal number), on the formation of temperature fields both near the heater and in the entire region. Is carried out the estimation of the average temperature, depending on the Sh

Influence of strouhal number on the temperature fields in the locked space with the working source of the radiant heating

Is carried out a numerical study of the heat transfer process in the closed domain with the source of radiant heating. Is solved the system of differential equations in the dimensionless setting, which describes free convection in the airspace and thermal conductivities in the enclosing constructions. Examined the influence of the dimensionless parameter, which characterizes the unsteady motion of liquids or gases (Strouhal number), on the formation of temperature fields both near the heater and in the entire region. Is carried out the estimation of the average temperature, depending on the Sh

About the possible options for models of convective heat transfer in closed volumes with local heating source

Results of mathematical modeling of convective heat transfer in air area surrounded on all sides enclosing structures, in the presence of heat source at the lower boundary of the media are presented. Solved the system of differential equations of unsteady Navier-Stokes equations with the appropriate initial and boundary conditions. The process of convective heat transfer is calculated using the models of turbulence Prandtl and Prandtl-Reichard. Takes into account the processes of heat exchange region considered with the environment. Is carried out the analysis of the dimensionless heat transfer coefficient at interfaces “air – enclosures”. The distributions average along the gas temperature range are obtained

Conditions and Characteristics of Water Crystallization on the Working Surface of Evaporator Heat Pumps in Reservoirs with Low Temperatures

Is carried out the mathematical simulation of heat transfer processes in the small environment of vaporizer camera of heat pump (HP) when the source of low-potential energy is present. Are obtained the temperature distributions, which characterize thermal condition HP. Is carried out the comparative analysis of the results of mathematical simulation and experimental data from the work of heat-pumping installation in the conditions of relatively low (up to 4 °C) temperatures. In the experiments, the partial freezing around of the tubes of vaporizer is established. It is revealed, that the formation of the layer of ice on the surface of vaporizer leads to the temperature contrast by the volume of liquid in the camera and reduction in the effectiveness in the work of heat-pumping installation

Prognostic potential of free convection models for analysis of thermal conditions of heat supply objects

The article shows the results of mathematical simulation of convective turbulent heat transfer in the closed domain with heat-conducting walls and the source of heat emission. The system of equations in the model of thermal conductivity for the solid walls and Navier-Stokes equations for gas are solved. The article examines the possible versions of the calculation of the turbulent regime in the geometrically simple air region by means of conducting the simulation within the framework of algebraic models (Van Driest and Prandtl-Reichardt), and k-ε model. On the basis of the obtained results the authors made a conclusion about the possibility of applying the algebraic model of Prandtl to describe the integral characteristics of turbulent flows in the conditions of natural convection in a geometrically simple area when the air heated by the heat source is moved by the lifting force. Besides, the temperature fields for a typical real object of heat supply are simulated in the article. The values of the dimensionless heat exchange coefficient at the air-wall interface are determined. The comparative analysis of two quite significantly different approaches to determine the average temperature in the heated room, i. e. the traditional balance approach and the approach based on the considered system of partial differential equations is executed. It is concluded that the balance models of the calculation of the temperature regime can adequately describe real temperatures of heat supply objects only for very large values of the characteristic times of the processes in question

Conjugate heat transfer in a closed volume with the local heat sources and non-uniform heat dissipation on the boundaries of heat conducting walls

Is solved the problem of heat transfer in the closed volume, limited by heat-conducting walls, with the local source of heat emission and the heterogeneous conditions of heat sink on the outer boundaries of solution area. The problem of convective heat transfer is solved with using a system of differential Navier-Stokes equations in the Boussinesq approximation. The simulation of turbulent flow conditions of heated air is carried out within the framework to k-ε model. On the basis the analysis of the obtained temperature field and the contour lines of stream functions is made conclusion about the essential transiency of the process in question. The obtained values of temperatures and speeds in different sections of region illustrate turbulence of the process. Are investigated laws governing the formation of temperature fields in closed areas with a local heat emission source under the conditions of intensive local heat sink into environment and accumulation of heat in the enclosing constructions

Influence of Local Zones of Intensive Heat Transfer on Thermal Regime of Heat Supply Objects

The results of mathematical simulation of conjugate heat transfer for heat supply object are represented. The turbulent regime of air motion in a closed cavity with the enclosing walls from reinforced concrete and glass is examined. On the outer boundary, which includes window aperture, the conditions of convective-radiation heat exchange with environment are realized. Is solved the system of the dimensionless equations within the framework of thermal conductivity model for the solid walls and Navier-Stokes for the gas. The influence of the local zones of intensive heat transfer on the thermal regime of the heat supply objects is established. Are determined the values of the dimensionless heat exchange coefficient on division border “air - wall”. The analysis of the values of mean temperatures of the solution region is carried out