Numerical Simulation Of Thermal Processes Research Articles

Numerical simulation of thermal processes in cold metal transfer-based additive manufacturing

Numerical simulation of thermal processes in cold metal transfer-based additive manufacturing

Modeling of thermal processes in vertical heat exchangers of ground-source heat pump

The basic directions for perfection heat supply systems are the tendency of transition to the low-temperature heating systems based at application heat pump installations. We consider heat supply systems with ground-source heat pump. The paper considers modeling the efficiency of ground-source heat pumps with the account of Ukrainian climate conditions. The paper presents the energy performance criteria which show the way to rational implementation of ground-source heat pumps for heating. A computational model based at non-stationary heat exchange processes in elements of ground-source heat pumps is developed. Generalization and analysis of theoretical and experimental dates allow establishing nature of dependence thermophysical properties on temperature insoil around ground heat exchangers during long term operation of the system. Numerical simulation of thermal processes in vertical ground pipes for ground-source heat pump working with low-temperature heating systems has been worked out. The results of numerical modeling demonstrated perfection and technical adaption of ground-source heat pump for low-temperature heating systems with rational using ground energy potential. The novelty of our method is complex usage theoretical and experimental results which enable to prevent freezing in the ground during long term exploitation This provides insights at effects of different resource mixes and may serve as a new approach to analysis of future heat pump systems using ground source energy development.The proposed method contributes to the field of creation and implementation the sustainable heating technologies using renewable energy sources. The ground heat exchange pipes quantities that are necessary for effective operation heat pump installation, capacity and coefficient of performance with the account of climate conditions are calculated.

Numerical Simulation of Thermal Processes and the Effect of Heating of Near-Surface Layers of Titanium on the Diffusion Transfer of Dopants during High-Intensity Pulsed Ion Implantation

Numerical Simulation of Thermal Processes and the Effect of Heating of Near-Surface Layers of Titanium on the Diffusion Transfer of Dopants during High-Intensity Pulsed Ion Implantation

Modeling and optimal design of liquid cooling system of electronic module

Formulation of the problem. Optimal design of avionics (avionics) structures is impossible without the development of new complex methods for modeling thermal processes in their designs and verification based on the results of a full-scale experiment, as well as the creation of methods for the justified use of existing and creation of new mathematical algorithms for optimization procedures. When designing modern RES, it is important to provide a temperature regime for the functioning of power elements of the equipment, in our case, we will consider an electronic module. To ensure normal thermal conditions, cooling systems are used, most often heat sinks (radiator) are used, but in some cases it is not possible to install it. To solve this problem, it is proposed to develop a liquid and air cooling system for the electronic module using an expanded set of elements of cooling systems, including a submersible cooling system. Purpose. Develop a comprehensive methodology for modeling and optimal design of a liquid cooling system for an electronic module, the reliability of which is confirmed by the results of analytical calculations and experimental data. Results. On the basis of the developed 3D model of the electronic module, the procedures for multivariate analysis of the laboratory stand unit were implemented using modern computer-aided design tools. A mathematical formulation was formed and procedures for optimizing the thermal regime were performed: modeling and optimization of the coolant; block topology optimization; optimization by body material and coolant type. Graphs and tables of simulation results are presented, on the basis of which it is possible to draw conclusions about the influence of a particular parameter on the distribution of heat fluxes. All the difficulties that the authors encountered in the course of design optimization in the modeling environment are described in detail, as well as ways to solve them. Practical significance. The results obtained make it possible to apply the proposed method for numerical simulation of thermal processes in REM designs, verification based on the results of a full-scale experiment, as well as the creation of methods for the justified application of existing and the development of new mathematical algorithms for optimization procedures.

Numerical Simulation of Thermal Process in a Phase Change Material Exposed to Solar Heating in a Tropical Region

The capacity for phase change material (PCM) to absorb and release latent heat has led to its applications in heating/cooling strategies in solar heating systems, air-conditioning system, electronics cooling and food preservation. The use of PCM in building construction through micro/macro-encapsulation to passively cool/heat a living space has attracted a lot of experimental and simulation research work, especially after the turmoil caused due to worldwide energy crises. In this paper, the thermal behaviour of a PCM exposed to solar heating in a tropical climate is studied numerically over a 24-hour period using the ANSYS fluent Software. A grid dependency test is initially devised to establish the most appropriate grid sizes and time steps to be used for the subsequent simulations with acceptable accuracy. PCM is setup to be in contact with one side of a concrete block. The other side of the concrete is exposed directly to a typical daily solar radiation profile of a tropical region. Results, in terms of temperature distribution and liquid fraction, show that a two-layer of a commercially available PCM is sufficient to flatten the temperature fluctuations arising from solar heating in the tropical regions.

Polyethylene pipe socket welding technology in mining

The proposed technology of polyethylene pipe socket welding can be used in construction of polyethylene piping systems in the mining industry. Based on numerical simulation of thermal process, the effect of low temperatures on the temperature field dynamics in socket weld joint is investigated. The need of preheating and usage of thermal insulation at the cooling stage during welding at low temperatures for the thermal process to develop according to the patterns of welding at acceptable temperatures is shown. A procedure is given for determining the size of a heat-insulating chamber for cooling a welded socket joint at low temperatures from the condition of ensuring the cooling rate characteristic of welding at permissible temperatures.

Numerical simulation of thermal processes occurring in materials under the action of femtosecond laser pulses

In this work, a numerical study of the solutions of the parabolic and hyperbolic equations of heat conduction with the same physical parameters is carried out and a comparative analysis of the results obtained is carried out. The mathematical formulation of the problem is discussed. The action of the laser is taken into account through the source function, which was chosen as a double femtosecond laser pulse. In the hyperbolic equation, in contrast to the parabolic one, there is an additional parameter that characterizes the relaxation time of the heat flux. In addition, the source of the hyperbolic equation contains an additional term - the derivative of the power density of the source of the parabolic equation. This means that the temperature of the sample is influenced not only by the power density of the source, but also by the rate of its change. The profiles of the sample temperature at different times and its dynamics at different target depths are shown. The calculations were carried out for different time delays between pulses and for different relaxation parameters.

Active Thermal Testing of Delaminations in Heat-Shielding Structures

We describe possibilities offered by active thermal testing when detecting delaminations of heat-shielding coatings from a metal base using an optical thermal-stimulation source that implements heating in a scanning mode. Results of numerical simulation of thermal processes are given for various defective situations. The thermophysical characteristics of heat-shielding materials have been experimentally determined, and the limits of the thermal method have been estimated for heat-shielding thickness and defect size.

激光-MIG复合焊接热过程与熔池流场的数值分析

激光-MIG复合焊接热过程与熔池流场的数值分析

Numerical Simulation of Thermal Processes in a Domain of Thin Metal Film Subjected to an Ultrashort Laser Pulse.

A thin metal film subjected to an ultrashort laser pulse is considered. With a sufficiently high laser intensity the process of the film heating may cause metal melting and even ablation. In this work, the numerical model of the melting and resolidification processes is presented. The mathematical model is based on the dual phase lag equation in which two positive constants appear, this means the relaxation and thermalization times. The considered equation contains a second-order time derivative and higher order mixed derivative in both time and space and should be supplemented by the appropriate boundary and initial conditions. The model of the melting and resolidification is presented in two versions. The first can be called ‘the introduction of the artificial mushy zone sub-domain’, while the second ‘the two forms of the basic energy equation’. At the stage of numerical computations, the implicit scheme of the finite difference method is used. The numerical algorithm is tested for the two proposed models which are applied to the computations concerning the thermal processes occurring in the cylindrical micro-domain (chromium, gold) subjected to an ultrashort laser pulse.

Numerical Simulation of Thermal Processes in Welding with Pulsed Electrode Wire Feeding

The use of computational methods allows us to significantly shorten the time required for researches and save welding and other consumables. In addition, the computational methods used in studies make it possible to demonstrate the obtained results with a high degree of accuracy. Computational methods are based on computer-aided mathematical modeling of welding processes. Mathematical modeling is applied specifically to develop models adequately describing various welding processes or interrelation between those processes. The article describes the model that demonstrates the distribution of temperature fields in butt joints during the arc welding with pulsed electrode wire feeding.

Progress in Numerical Simulation of Thermal Processes and Weld Pool Behaviors in Fusion Welding

Progress in Numerical Simulation of Thermal Processes and Weld Pool Behaviors in Fusion Welding

Tool Design Influence on the Thermal Effects Appearing during Bevel Gear Processing

Toothing of bevel gear is a crucial operation for the automobile industry. To achieve the required performance characteristics of the gear it is essential to optimize the toothing process. Herewith, the task of understanding the proceeding the heat processes during cutting is important to forecast of the tool wear, accuracy, and undulation of the processed surface. In the article the results of numerical simulation of thermal processes appearing during processing of bevel gear are considered. This paper presents the results of numerical modeling of thermal processes occurring in a tool, workpiece, and chips during bevel gear cutting. Also the influence of the design parameters of the cutting tool on the value of maximum temperatures and heat flows occurring in the process of cutting was investigated. The approaches which were used in that paper can also be applied to other cutting processes with the removal of a complex U and / or L shaped chips (gear shaping, broach etc.)

Numerical Simulation of Thermal Processes Involved in Surface Alloying of Aluminum with Titanium by an Intense Pulsed Electron Beam

The temperature fields arising in a Ti film – Al substrate system and bulk Ti specimen irradiated with a submillisecond intense electron beam are calculated in the one-dimension approximation. It is found that the temperature fields in the irradiated bulk Ti specimen and Ti film – Al substrate system differ greatly. Electron beam irradiation conditions which allow solid-phase and liquid-phase alloying of aluminum with titanium are defined

Numerical simulation of thermal processes in the elements of MHD-pumps used for transferring liquid metals

The paper is devoted to numerical simulation of the non-stationary thermophysical processes occurring in the liquid metal feed pipe of MHD pumps. The non-stationary heat-conduction problem is formulated and solved numerically by the finite element method using ANSYS software. The results of numerical simulations are compared with the previously obtained experimental data. A series of numerical computations have been carried out to estimate the influence of different parameters on the process of pipe heating, which allowed us to determine the optimal parameters ensuring effective operation of MHD-pumps.

Numerical Simulation of Thermal Process in Rotary Hearth Furnace for Pellet Direct Reduction

A mathematical model of complex thermal processes with combustion, radiation and flow in rotary hearth furnace (RHF) for pellet direct reduction is established with CFD commercial software Fluent. Temperature distribution, pressure field and flow field in RHF are simultaneously analyzed by numerical method. It has been found that the temperature distribution in the furnace can meet the need of thermal institution for pellet direct reduction, and great pressure field and flow field can be formed on the basis of reasonable arrangement of burner, nozzle and partition. The simulation results would be helpful for engineering design and parameter optimization of RHF.

Role of experiments in the accurate numerical simulation of thermal processes

PurposeExperimental results play a crucial role in the validation of mathematical and numerical models for a variety of basic and applied thermal transport problems. The purpose of this paper is to focus on the role played by experimentation in an accurate numerical simulation of thermal processes and systems.Design/methodology/approachThe paper takes the form of a numerical simulation combined with experimentation. The paper presents various circumstances where the numerical simulation may be efficiently combined with experimentation, and indeed driven by experimental data, to obtain accurate, valid and realistic numerical predictions.FindingsThe paper demonstrates validation and accuracy of numerical simulation.Originality/valueThis paper is an important first step in combining experiments and simulation for complex thermal systems.

Numerical simulation of thermal process and energy saving of lime furnace

Based on the principle of thermal balance and material balance of lime furnace, the reaction and heat transfer process mathematical-physical model and the on-line monitoring model of the decomposition rate of limestone were set up. With this model, numerical simulation is used to analyze the effects of operational parameters on the process of lime calcining and to optimize it. By using visual basic program to communicate and program, the centralized management and automatic control of the lime furnace are realized. The software is put into practical production, which makes the lime furnace operate steadily and efficiently, and causes the increase in output and decrease in energy consumption.

Recent developments in numerical simulation techniques of thermal recovery processes

Numerical simulation of thermal processes (steam flooding, steam stimulation, SAGD, in-situ combustion, electrical heating, etc.) is an integral part of a thermal project design. The general tendency in the last 10 years has been to use commercial simulators. During the last decade, only a few new models have been reported in the literature. More work has been done to modify and refine solutions to existing problems to improve the efficiency of simulators. The paper discusses some of the recent developments in simulation techniques of thermal processes such as grid refinement, grid orientation, effect of temperature on relative permeability, mathematical models, and solution methods. The various aspects of simulation discussed here promote better understanding of the problems encountered in the simulation of thermal processes and will be of value to both simulator users and developers.

Numerical simulation of thermal process in steel industry

This note deals with a simulation algorithm for a reheating process of long steel products. In the steel industry, it is not always possible to measure the temperature of slabs during the reheating process. Therefore the well-known two-dimensional model of heat conduction with mixed convection-radiation boundary conditions is considered. This non-linear distributed system is discretized according to an implicit finite difference scheme and the temperature distribution of slabs is computed at each time instant by an efficient iterative algorithm.