Thermophysical Calculation Research Articles

MODELING OF HEAT-STRENGTH INTERACTION OF FUEL AND STRUCTURAL MATERIALS OF AN IRRADIATING DEVICE IN THE ANSYS SOFTWARE

In the work, a conjugate thermo-strength analysis was carried out for the ID-7 experimental device (ED) model. The calculation was carried out using bundles of Ansys Fluent and Static Structural programs in the Ansys Workbench environment using the Fluid-Structure-Interaction (FSI) method. The calculation of the thermal state of the ED was carried out taking into account the results of neutron-physical calculations, using the user function UDF (User Defined Function) of the Ansys Fluent program. According to the results of the non-stationary calculation, the temperature values are obtained, which vary in time and in the height of the ED. Based on the results of the thermophysical calculation, a strength calculation was carried out in the Static Structure program. Distributions of the magnitude of thermal expansion and mechanical expansion (von-Mises) in the elements of the ED are obtained.

Improving the thermal protection characteristics of building enclosing structures of the Samara Academic Drama Theater building

Preservation of the architectural appearance of buildings of historical and cultural heritage is a prerequisite for their energy modernization when performing major repairs or reconstruction. In this regard, it is not possible to use facade systems to reduce heat losses by external walls. The use of internal insulation, as construction practice has shown, quite often led to a violation of the humidity regime of enclosing structures and, as a result, to the formation of dark spots and mold fungi on the internal surfaces. To prevent moisture accumulation in enclosing structures, with internal insulation, only thermal insulation materials with a low coefficient of vapor permeability should be used. The article presents the results of a thermal imaging survey of the facades of the Samara Academic Drama Theater building, which indicate increased heat loss in the basement of the building and the exterior walls made of silicate bricks after reconstruction in 1967. In order to meet modern regulatory requirements for the thermal protection of buildings of historical and cultural heritage, it was proposed to additionally insulate the exterior walls from the inside above the zero mark with foam glass, as well as warm plaster in the basement and basement of the building. Solutions are proposed for the replacement of window structures, entrance doors, coverings and ceilings to increase the energy efficiency of the operated building. When performing the thermophysical calculation of the above-listed enclosing structures, the authors methodology for estimating the plane of possible condensation was applied, which allows for a higher probability of assessing moisture accumulation in them.

МОДЕЛИРОВАНИЕ НЕСТАЦИОНАРНОГО ТЕПЛОВОГО РЕЖИМА ПОМЕЩЕНИЯ С ДЕРЕВЯННЫМИ ОГРАЖДАЮЩИМИ КОНСТРУКЦИЯМИ

A non-stationary approach to the calculation of periodic thermal regimes of low-rise buildings with enclosing structures made of wooden beams equipped with double-glazed windows is considered. The application of the proposed method allows to determine the non-stationary thermal load of the air conditioning system for this type of house, as well as the required compensating capacities during the day. The conditions of applicability of plane-layered thermophysical calculation schemes in the presence of spatially inhomogeneous heating are analyzed. A refinement of the procedure for averaging convective heat transfer coefficients for vertical walls by periodic temperature fluctuations is carried out. An algorithm for calculating the periodic thermal regime based on the representation of time dependencies in the form of a Fourier series is proposed. The role of solar radiation flow through double-glazed windows in the heat exchange and energy efficiency of a wooden house is shown. The proposed mathematical model of room heat exchange takes into account the effects of the delay in the propagation of the temperature field in the walls when the ambient temperature changes and the dynamic change in heat flux from light flows outside and inside the room. It is determined that protection from direct sunlight entering the room through the window opening allows reducing peak air conditioning costs in the summer by a third for peak air conditioning modes.

Using a user–defined function in Ansys Fluent to implement the energy release profile in model fuel elements taking into account radiation heating

The paper presents a model of an experimental device tested on the complex of impulse graphite reactor of the Branch IAE RSE NNC RK, designed to study the possibility of changing the neutron spectrum of the reactor from thermal to fast. At the stage of preparation for testing, a series of neutron-physical studies were carried out using the MCNP. The purpose of these studies is to determine the specific energy release both in the model fuel elements and in non-fuel structural elements of the experimental device during their radiation heating, taking into account the thermal state of the reactor core. After that, the obtained data are used as initial conditions for development of user-defined functions and conducting thermophysical calculations to determine the distribution of the temperature field in the tested device, the ANSYS Fluent software package. The method for calculating the specific energy release in non-fuel structural elements during their radiation heating in the impulse graphite reactor, considering its thermal state, has been used relatively recently. It requires a special approach to the implementation of the required energy release profile when carrying out thermophysical calculations in the Ansys software. The paper also illustrates the advantages of using a custom function in Ansys Fluent to define the profile of the energy release in model fuel elements and structural elements of an experimental device depending on time and height. In addition, the results of a thermophysical calculation of the experimental device for determining the distribution and maximum values of temperature in fuel and non-fuel structural elements are presented.

MODELING OF THE INDUCTION HEATING FOR IMITATION DECAY HEAT IN THE CORIUM DURING THE INTERACTION WITH HEAT-RESISTANT MATERIALS

This work is devoted to modeling of the induction heating the corium melts pouring on in the trap. The results nonstationary thermophysical calculation of the temperature field of the corium and refractory blocks of the melt trap are presented in the article. In the process of work, 2D model of the selected the melt trap area was created in the program ANSYS and the thermophysical model was validated by comparison the calculated and experimental data of the experiment.

ИССЛЕДОВАНИЕ МНОГОСЛОЙНОГО НАРУЖНОГО ОГРАЖДЕНИЯ, ВКЛЮЧАЮЩЕГО В СЕБЯ МАТЕРИАЛЫ С ИСПОЛЬЗОВАНИЕМ ЗОЛОШЛАКОВЫХ ОТХОДОВ ТЭЦ

the most important direction of resource saving in construction is the widespread use of secondary material resources, which are waste products. The use of secondary products of industry as raw materials for the production of various building materials is very important, because it provides production with rich sources of cheap and, often, already prepared raw materials; lead to lower costs for the production of some building materials, and therefore saves capital investments intended for the construction of buildings and structures; release large areas of land and reduce the impact on the environment. The article deals with heat-insulating and structural-heat-insulating materials, with partial replacement of components by ash-slag waste (ASW): lightweight concretes with broken glass and concretes modified with sulfur. Properties of concretes modified with sulfur are investigated: compressive strength, density and thermal conductivity. In accordance with the obtained properties, a comparative characteristics of the received materials with existing building materials was carried out: sulfur modified concrete and lightweight concrete; lightweight concrete using broken glass and claydite-concrete. Thermophysical calculation of multilayer hencing is made. In each of the options, one of the following materials was selected as a structural and heat-insulating material: lightweight concrete using broken glass and sulfur modified concrete. Also, for each type of hencing, the necessary heat-insulating and structural materials were selected. In the economic part, the cost of the raw materials necessary to obtain 1 m3 of the investigated materials and the cost of 1 m3 of multilayer hencing, which includes the investigated concrete, are calculated.

Calculation of railway tunnels ventilation

"As a result of aerodynamics calculation the total stream of air flow from piston effect of moving train and effect after movement has been determined ('effect after movement' - The residual movement of air due to the inertia of the moving air mass, when the train has already left the tunnel and the piston effect is no longer directly in effect. So residual motion adds some air stream to the main air flow) in the railway tunnel of the Marabda-Akhalkalaki. It has been determined that for the condition of those tunnels, approximately 2/3 of air flow arisen from piston effect moves in the same direction as the train moves, while the rest flows to the opposite direction into the gap the perimeters of tunnel and train. This causes air turbulence and represents component of the general aerodynamic resistance. Despite of that, all galleries of the mentioned rail highway can be aired with natural draught resulted from piston effect. For the better use of draught, caused by the piston effect ventilation gaps should be arranged in each camera and niche, on both sides of the tunnel. The area of wide section in each air hole should be 5.6 m2. This activity will decrease aerodynamic resistance caused by the airflow in the gap of the tunnel and will guarantee air supply in the tunnel using piston effect. Thermo-physical calculation of tunnels ventilation has been performed and the work project for ventilation has been prepared. The present article sets out the results of the longest tunnel calculation. The presented results may be adjusted to shorter tunnels as well, because corresponding parameters for their conditions are milder and thus, appropriate to the norms. According to the calculation, the heat produced by the moving train can be neutralized with air flow of 4.8 m3/s in winter and 8.4 m3/s in summer. These air flows make sure to satisfy requirements for the maximum temperature so the temperature of airflow coming from the tunnel shall not exceed 35 ° C. 0 for any season. "

Bismuth-Telluride-Based Radiation Thermopiles Prepared by Pulsed Laser Deposition

Radiation thermopiles are structural units of sensors used for measuring the energetic parameters of radiation in the wavelength range from 0.1 to 100 µm. The question of the application potential of p-Bi0.5Sb1.5Te3 and n-Bi2Te2.7Se0.3 films prepared by pulsed laser deposition in radiation thermopiles on different substrates was studied. It is shown by thermophysical calculation and the experimental studies of prototypes that the use of polyimide substrates may provide a responsivity of about 1 V/W for an absorption area 16 mm in diameter (the time constant is about 10 s).

氨水混合工质热物理性质计算现状及展望

氨水混合工质热物理性质计算现状及展望

Modelling of heating of plasma-chemical reactor in Comsol Multiphysics.

For the thermophysical calculation of the reactor, a mathematical model was developed in Comsol Multiphysics, describing physical processes in the plasma-chemical reactor at a stationary mode. To simplify the calculation at this stage, it was carried out for an air plasma torch. The model includes two processes: fluid dynamic and heat transfer ones. As a result of the mathematical modelling the following parameters were obtained: temperature distribution in the reactor at steady state, average mass temperature in the reaction volume, velocity field and others.

Development of thermophysical calculator for stainless steel casting alloys by using CALPHAD approach

The calculation of thermophysical properties of stainless steel castings and its application to casting simulation is discussed. It is considered that accurate thermophysical properties of the casting alloys are necessary for the valid simulation of the casting processes. Although previous thermophysical calculation software requires a specific knowledge of thermodynamics, the calculation method proposed in the present study does not require any special knowledge of thermodynamics, but only the information of compositions of the alloy. The proposed calculator is based on the CALPHAD approach for modeling of multi-component alloys, especially in stainless steels. The calculator proposed in the present study can calculate thermophysical properties of eight-component systems on an iron base alloy (Fe-C-Si-Cr-Mn-Ni-Cu-Mo), and several Korean standard stainless steel alloys were calculated and discussed. The calculator can evaluate the thermophysical properties of the alloys such as density, heat capacity, enthalpy, latent heat, etc, based on full Gibbs energy for each phase. It is expected the proposed method can help casting experts to devise the casting design and its process easily in the field of not only stainless steels but also other alloy systems such as aluminum, copper, zinc, etc.

Calculation of thermophysical properties of ternary aluminium alloys in non-equilibrium state

In the present study, a unique method for calculating solidification sequence and related thermophysical properties in the non-equilibrium state is explained. It is well known that accurate thermophysical properties of the aluminium casting alloys are necessary for the valid simulation of the casting processes. There have been a number of thermophysical calculation programmes; however, the programmes require specific knowledge of the thermodynamics. The calculation method proposed in the present study does not require any special knowledge of thermodynamics but only information on the compositions of the alloy. The proposed calculation tool was based on the CALPHAD approach for modelling multicomponent alloys.

Calculation of thermophysical properties of iron casting alloys

A simple and easy calculation tool to determine thermophysical properties, such as density, heat capacity, liquidus and solidus temperature, thermal conductivity, latent heat, and volume contraction, of iron casting alloys based on equilibrium phase diagrams is introduced. It is well known that accurate thermophysical properties of iron casting alloys are necessary for a valid simulation of the casting process. While there are a number of thermophysical calculation programs, a specific knowledge of thermodynamics is required to operate them. The calculation method proposed in the present study does not require any special knowledge of thermodynamics, only information regarding the composition of the alloy. The proposed calculation tool is based on the CALPHAD approach for the modelling of multicomponent alloys using experimental published data. Comparison of calculated thermophysical properties for several conventional iron casting alloys with experimental results showed good agreement.

Modeling and Simulation of Production Process on Dimethyl Ether Synthesized from Coal-based Syngas by One-step Method

As a result of shortage supply of oil resources, the process for the alternative coal-based fuel, dimethylether (DME), has emerged as an important process in chemical engineering field. With the laboratory experimentdata about DME synthesis and separation, the production process for DME with high purity is proposed when one-step synthesis of DME in slurry bed reactor from syngas is adopted. On the basis of experimental research andprocess analysis, the proper unit modules and thermophysical calculation methods for the simulation process are selected. Incorporated the experimentally determined parameters of reaction dynamic model for DME synthesis, regression constants of parameters in non-random two-liquid equation (NRTL) model for binary component in DMEseparation system with built-in properties model, the process flowsheet is developed and simulated on the Aspen Plus platform. The simulation results coincide well with data obtained in laboratory experiment. Accordingly, the accurate simulation results offer useful references to similar equipment design and process operation optimization.

Beneficial Effects of Freezing Rate Determined by Indirect Thermophysical Calculation on Cell Viability in Cryopreserved Tissues

Many types of mammalian cells, such as sperm, blood, embryos, etc., have been successfully cryopreserved for the last few decades, while no optimal method for the cryopreservation of mammalian tissues or organs has been established, showing a poor survival after thawing with a low recovery of function. In this study, the freezing rate was determined by indirect thermodynamic calculation, and its potential effect on the cryoprotection of human saphenous veins and tissue-engineered bones was investigated. The vein segments were frozen according to the calculated freezing rate, using rate-controlled freezing devices, with a freezing solution composed of 10% dimethylsulphoxide and 20% fetal bovine serum in RPMI 1640 media. The efficacy of indirect calculation was assessed by the cell viability measured using fluorescence double-staining methods. The results indicated that the freezing rate determined by indirect calculation significantly (P < 0.05) maintained the post-thaw cellular viability of the blood vessel, particularly in terms of the endothelial cells. However, it exerted relatively less protective effect on the osteoblastic cell-cultured scaffolds. These results suggest that freezing-induced injuries may occur in tissues, and the freezing rate determined by indirect thermophysical calculation can be used for the optimization of tissue cryopreservation by minimizing the injuries.

Effect of the nonaxial symmetry of an emitter-collector system on the temperature field of a thermionic fuel element

In algorithms and programs for calculating the temperature field of a thermionic field element, the cross section of the element is considered on the basis of the model of solid coaxial cylinder. In a real fuel element, however, the emitter-collector system is nonaxisymmetric because of the waviness and ovality of the surfaces, the emitter is eccentric relative to the collector, and the volume heat release in the fuel of the element is nonaxisymmetric. The distributions of the temperature and the heat fluxes transmitted through the emitter-collector system with allowance for these factors can be found only by using two-dimensional (cross-sections) methods of fuel-element calculation. In this paper, the authors report the results from the calculation of the temperature field in a thermionic fuel element with emitter-collector eccentricity and nonaxial symmetry of the volume heat release in the fuel with allowance for the thermomechanical deformations caused by that field. For the calculations, a two-dimensional program of thermo-physical fuel-element calculation, based on the method of finite elements, was adapted for this problem.

Temperature field in heat-liberating piles of fast reactors

The accuracy of thermophysical calculation of heat-liberatlng piles (HLP) of fast reactors is determined to a considerable extent by the accuracy of the initial calculational model of the fleld-element bundle and also by,taking correct account of all the factors influencing the formation of a temperature field in the bundle. The calculation is usually conducted for nominal parameters of the fuel elements and the HLP, under the assumption of a regular arrangement of fuel elements at the points of a regular triangular grid. For this model, the distribution of the heat-carrier flow rate over the individual channels, the heating of the heat carrier in the most stressed channels, and the corresponding temperature of the fuel-element casing are calculated for this model.

Thermophysical calculation of asphalt deformation-joint seals on hydraulic installations

Thermophysical calculation of asphalt deformation-joint seals on hydraulic installations