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The arc furnace is an important equipment in the production of manganese ferroalloys. In the smelting process, it produces high temperature flue gas above 700 K, which has high utilization value. During the pelleting process, moisture exists on the surface and inside of the pellets, which, if directly fed into the arc furnace, will lower the temperature of the furnace, affecting the production, and will also cause the pellets to burst, resulting in pressure fluctuations in the furnace and other hazards. The preheating shaft kiln reduces the moisture content of the pellet while preheating the pellet by utilizing high temperature flue gas. In this paper, through the establishment of porous media and shrinking core coupling mathematical model, to achieve the prediction of the heating and drying process of the pellets of various particle sizes, which is in good agreement with the production monitoring data. The results show that 9~11 mm pellets have the best preheating effect in terms of tail gas temperature, pellet temperature and preheating time. [ABSTRACT FROM AUTHOR]

As a core cooling device of reactor, a high temperature sodium heat pipe is designed in this paper which has a large aspect ratio of 126. The effects of heating mode and evaporation section length on its start-up are studied experimentally. The results show that the axial temperature uniformity of the heat pipe is better under variable power heating mode. As the evaporation cross-section length increases, thermal resistance decreases by 50%. Compared with heat pipes with low aspect ratio, heat pipes with large aspect ratio are more difficult to start up. Furthermore, numerical simulation is conducted on the designed sodium heat pipe to acquire the velocity and pressure distribution during steady-state operation. [ABSTRACT FROM AUTHOR]

This paper studies a self-designed high temperature fireball quasi-static simulation device to understand the temperature distribution of each substance inside the fireball under the multi-pipe injection technology. The changes in the physical field of the high temperature fireball are obtained through numerical simulation. The simulation model in this paper adopts the turbulent k-ε model, and simulates the material transfer process according to Fick's law. The commercial software COMSOL multiphysics is used to give and analyze the local characteristics of fluid-flow and heat transfer. The simulation device formed a high temperature fireball under the interaction of the three-way jet fire. The experimental data verified the accuracy of the simulation results, and the experimental results were in good agreement with the simulation results. This method of analyzing the actual temperature field through simulation can be used to provide a powerful verification scheme for the detection of complex multi-temperature fields in the future. [ABSTRACT FROM AUTHOR]

Based on the laser flash method, the selection of experimental parameters on the accuracy of measurement results for measuring thermal diffusivity is investigated in this paper. High purity graphite is employed as the experimental material. Three experimental parameters are taken into consideration, including specimen thickness, laser pulse power, and laser pulse width. Firstly, the principle of the laser flash method is introduced. Then, a numerical simulation model is established and independence tests are performed. In order to investigate the impact of different experimental parameters to the precision of the measurement results using the laser flash method, six thicknesses of the specimens, five laser pulse powers, and five laser pulse widths are selected for numerical simulation and LFA 427 measurement experiments. Finally, an orthogonal design method with three-factor and three-level is constructed to investigate the influence degree of these three factors on the measurement results. It is found that the laser pulse width has the most significant influence, while the laser pulse power has the least impact. For high purity graphite specimens, it is required to choose a thicker specimen, a lower laser pulse power, and a smaller laser pulse width to ensure better measurement accuracy. [ABSTRACT FROM AUTHOR]

By constructing the heat transfer model of the buried tube heat exchanger, using the mathematical method and numerical calculation software, the temperature of the buried tube heat exchanger is calculated numerical, so as to better understand the temperature effect of the buried tube heat exchanger on the surrounding soil. This paper establishes a mathematical model of a vertically buried heat transfer system based on the principle of thermal equilibrium and the thermal conductivity differential equation. Conduct research on the temperature field around single pipes in different soil (geological conditions), temperature field under different drilling backfill materials, and the temperature around buried pipe-lines in both short-term and long-term operation of the system. The experimental results show that the simulation results of the system's short time (10 days) and long time (90 days) performance show that the cooling and temperature cycles in different areas directly affect the heat radius of the buried pipe and the heat accumulation near the buried pipe. The thermal action radius of the short-term operation system is about 1.8 m, and the long-term operation reaches 4.5 m. [ABSTRACT FROM AUTHOR]

In this paper, ASPEN PLUS commercial software is used to simulate the plasma gasification process of oil-based drilling cuttings, and the numerical simulation results are analyzed in detail. The conclusions can provide theoretical guidance for subsequent experiments and practical engineering applications. A set of reactor models suitable for gasification of such substances was established by using Gibbs' free energy minimization principle, and the accuracy of the model was verified by comparing the numerical simulation results with the experimental results. In this model, the effects of plasma torch power, air equivalent ratio, moisture content of feed, and the amount of CO2 added on the gasification results were simulated. Through systematic analysis, the optimal gasification parameters are determined output power of plasma torch is 27.5 kW, air equivalent ratio is 0.26, moisture content of feed is 6%, and the amount of CO2 added is 6 kg per hour. [ABSTRACT FROM AUTHOR]

In order to study the heat dissipation characteristics of lithium batteries, a staggered bi-directional flow cooling method is designed and numerical simulations are established using CFD in this paper with a circular battery as the research object. Since the optimal operating range of Li-ion battery is 293.15-313.15 K and the maximum temperature difference is not higher than 5 K, the maximum temperature and maximum temperature difference are selected as the optimized design objectives. Firstly, the temperature field of the round lithium battery with discharge multiplier 3C working at ambient temperature 308.15 K is studied, and an orthogonal test design is carried out for three factors: battery pack embedding distance, coolant flow rate and coolant temperature, and the best combination of orthogonal test is selected by extreme difference analysis and analysis of variance. Secondly, in order to further verify the heat dissipation efficiency of the battery pack, a back propagation neural network with multi-objective optimization algorithm is proposed, and the optimal heat dissipation method of the numerical simulation is obtained by parameter solution and simulation analysis using the parameter range of the orthogonal test as the constraints of the multi-objective optimization. The results show that this optimized way of battery pack heat dissipation has a significant improvement for the maximum temperature, and non-e of them will exceed its working range; compared with the 3.39 K obtained from the orthogonal test design, the maximum temperature difference of the battery pack calculated by the multi-objective optimization is 3.15 K, which is reduced by 7.08%. [ABSTRACT FROM AUTHOR]

The cement industry is the second largest source of global man-made CO2 emissions after the power industry, and the adoption of O2/CO2 combustion technology for cement kilns is of great significance in reducing CO2 emissions. In this paper, the effects of pulverized coal mixed air combustion and pulverized coal mixed O2/CO2 combustion on the velocity field, temperature field, CO2 and NOx concentration distribution in rotary kiln were investigated by CFD technique. The results showed that there is no difference in the velocity distribution between the two atmospheres, and the speed difference between the primary and secondary air creates a re-circulation zone near the burner. The O2/CO2 atmosphere combustion decreased the maximum temperature, but improved the uniformity of the temperature field. The pulverized coal burnout rate under O2/CO2 atmosphere decreased by 3.55% compared to O2/N2 atmosphere. The mole fraction of CO2 at the rotary kiln outlet is 0.08 and 0.93 for O2/N2 and O2/CO2 combustion atmospheres, respectively. It is easier to achieve CO2 aggregation and capture under O2/CO2 atmosphere than under O2/N2. The NOx concentration at O2/CO2 is approximately one half of that at O2/N2, which can save the investment on denitrification equipment. The simulation results reasonably agree with the measured data. The findings of this work will provide a reference for the generalization and application of the O2/CO2 flue gas cycle calcinating cement technology. [ABSTRACT FROM AUTHOR]

Billet reheating is an important part of the steel production process. Since the production process will adopt different tube billet arrangement strategies, and the condition of the furnace hearth will also change due to long-term operation and accumulation of iron oxide scales, these factors will inevitably affect heating efficiency and temperature distribution uniformity of the tube billet, thereby affecting the quality of the final product. In this study, a physical and mathematical model was established for a 48 m diameter rotary hearth furnace of the seamless steel pipe production-line and typical 300 mm diameter tube billets of different lengths. Commercial FLUENT code was used to carry out CFD numerical simulation research on the influence of the aforementioned factors. Optimizing and adjusting strategies under different arrangement strategies were proposed, and the influence of furnace hearth condition change on heating effect was studied. The methods and simulation approach of this paper also have guidance for the billet heating control in similar continuous heating furnaces. [ABSTRACT FROM AUTHOR]

Shell and tube heat exchangers have great thermal stress due to the different fluid temperature and instability of the flow field. In this paper, based on the fluid physical model of shell and tube heat exchanger, the velocity field, pressure field and temperature field inside the heat exchanger are simulated and analyzed on Workbench platform. The numerical simulation shows that the baffle plate has a great influence on the internal flow field of the heat exchanger. [ABSTRACT FROM AUTHOR]

Freezing damage is one of the main diseases of tunnels in cold regions. Water storage behind the lining is a necessary condition for freezing damage. Compared with the previous condition of uniform water storage behind the lining, this paper explores the influence of water storage and frost heave at different positions on tunnel structure in cold regions. Based on the theory of thermo-hydro-mechanical coupling. The finite element model of tunnel surrounding rock in cold area under different positions and different water content is established and compared by using COMSOL software, the mechanical characteristics of tunnel lining under different water storage positions behind the lining are studied, and the influence of frost heave at different positions on tunnel structure is explored. The numerical simulation results show that no matter where the local water storage area is located, the area with the largest frost heave force is located in the lining structure, close to the surrounding rock. Different local water storage positions will also have different influences on the tunnel structure. In the same water storage area, the frost heave force will increase with the decrease of temperature. [ABSTRACT FROM AUTHOR]

Icing accretion on wind turbine will degrade its performance, resulting in reduction of output power and even leading to accidents. For solving this problem, it is necessary to predict the icing type and shape on wind turbine blade, and evaluate the variation of aerodynamic characteristics. In this paper the icing types and shapes in presence of airfoil, selected from blade of 1.5 MW horizontal-axis wind turbine, are simulated under different ambient temperatures and icing time lengths. Based on the icing simulation results, the aerodynamic characteristics of icing airfoils are simulated, including lift and drag coefficient, lift-drag ratio, etc. The simulation results show that the glaze ice with two horns presents on airfoil under high ambient temperature such as –5 ℃. When ambient temperatures are low, such as –10 ℃ and –15 ℃, the rime ices with streamline profiles present on the airfoil. With increase in icing time the lift forces and coefficients decrease, and the drag ones increase. According to the variations of lift-drag ratios of icing airfoil, the aerodynamic performance of airfoil deteriorates in the presence of icing. The glaze ice has great effect on aerodynamic characteristics of airfoil. The research findings lay theoretical foundation for icing wind tunnel experiment. [ABSTRACT FROM AUTHOR]

The radiative heat transfer in a high temperature granular bed of binary-size mixture was explored in this paper. The effective view factor between particles decreases exponentially with the increase in particle interval, increases with the increase in the size of the absorption particle but is hardly affected by the volume ratio of the mixture. The effective thermal conductivity of granular bed was further deduced basing on the characteristic of the effective view factor. It is indicated that the thermal conductivity is proportional to the particle size and temperature cubed, and increases with the increase in the particle size ratio and volume ratio. Finally, modified calculation correlations of the effective view factor and effective thermal conductivity were developed for binary-size bed based on the simulation results, and good accuracy of less than 0.01 and 10% had been achieved, respectively. [ABSTRACT FROM AUTHOR]

Ritz method is widely used in variational theory to search for an approximate solution. This paper suggests a Ritz-like method for integral equations with an emphasis of pantograph delay equations. The unknown parameters involved in the trial solution can be determined by balancing the fundamental terms. [ABSTRACT FROM AUTHOR]

Numerical study of NOx abatement in a photocatalytic reactor has been caught much attention recently. There are two ways for the numerical simulation, one is the CFD model, the other is the variational-based approach. The latter leads to a conservation algorithm with less requirement for the trial functions in the numerical study. In this paper we establish a variational principle for the problem, giving an alternative numerical method for NOx abatement. [ABSTRACT FROM AUTHOR]

In the process of bottom blowing bath smelting, continuous bubbles are formed and rise in the melt after the bottom blowing gas is ejected. In order to reveal the motion behavior and wake characteristics of continuous bubbles formed during the injection process, the rising process of coaxial double bubbles is studied through numerical simulation, the velocity and deformation characteristics of coaxial double bubbles in the rising process are obtained. Based on the vortex identification reconstruction of the flow field, the characteristics of formation, evolution, and configuration of bubble wake are obtained. The results show that in terms of motion characteristics, the aspect ratio of the upper bubble is always less than 1, and lower bubble has a large span of change: the minimum is 0.85 and the maximum is 1.2. As the two bubbles approach, the aspect ratio of the upper bubble is always less than 1, while the maximum aspect ratio of the lower bubble can reach 1.2. In terms of wake characteristics, the vorticity on the upper bubble surface is larger. When the wake rotation centers of the upper and lower bubbles merge with each other, the instantaneous acceleration of the lower bubble reaches the maximum. [ABSTRACT FROM AUTHOR]

Through the development of a mathematical model for micro-scale multi-phase flow of supercritical CO2 and a simplified geological reservoir micro-model, numerical simulations were executed using the open-source CFD software Open FOAM. The study systematically analyzed various engineering and geological parameters' influence on the micro-scale flow patterns of supercritical CO2 under reservoir temperature and pressure conditions. These insights provide guidance for designing process parameters in fracturing and storing supercritical CO2. [ABSTRACT FROM AUTHOR]

In this paper we present a second order numerical scheme for the Cahn-Hilliard equation, with a Fourier pseudo-spectral approximation in space. An additional Douglas-Dupont regularization term is introduced, which ensures the energy stability. The bound of numerical solution inH²h and ℓ∞norms are obtained at a theoretical level. Moreover, for the global nature of the pseudo-spectral method, we propose a linear iteration algorithm to solve the non-linear system, due to the implicit treatment for the non-linear term. Some numerical simulations verify the efficiency of iteration algorithm. [ABSTRACT FROM AUTHOR]

In this article, we mainly consider a modification of the high-order long water-wave equation with unsmooth boundaries by adopting a new fractal derivative. Its fractal variational principles are successfully constructed by the fractal semi-inverse method, the obtained principles are helpful to study the symmetry, to discover the conserved quantity, and to have wide applications in numerical simulation. [ABSTRACT FROM AUTHOR]

In order to further improve the crack resistance of concrete engineering, a numerical simulation method is constructed to study the effect of temperature on the fission of concrete. Based on the finite element method, the mathematical model is constructed, and the numerical calculation and image display are used to simulate and analyze the engineering problems. The temperature sensor is used to observe the whole variation law of typical temperature field, and the temperature of concrete entering and pouring is obtained. Thus, the temperature control real-time automatic acquisition system is set up. According to the temperature field and temperature stress distribution rules, the ideal temperature control curve model of concrete is proposed. Finally, the numerical calculation and experiment of the model are carried out. The results show that the maximum surface stress level decreases in varying degrees after different surface insulation measures are taken, and if the thermal insulation material's β = 10 kJ/m²h °C, the maximum surface stress of concrete can be reduced to 0.06~0.14 MPa. In this paper, it is shown that the negative effect of the large diurnal temperature difference on concrete surface insulation can be controlled. [ABSTRACT FROM AUTHOR]

Wettability plays a vital role in many fields. In this paper, the shortcomings of current experimental measurement of dynamic wetting characteristics are described. The dynamic wettability of droplets on the simplified triangular wave micro-structure surface is studied by volume of fluid method. The results are compared with the dynamic wettability of droplets on the smooth surface and the rectangular wave micro-structure surface. The results show the similarities and differences of the motion characteristics of droplets on smooth surface and different micro-structure surface. Under the action of volume force, the droplets are first deformed and then moved. The droplets move as a whole on the smooth surface. But the droplets partially slip on the micro-structure surface, and the threephase contact point on the left side does not move. [ABSTRACT FROM AUTHOR]

Standard bar of ventilation is the equipment extensively used in the tobacco industry to calibrate the variety of testing machines. The bar's performance that is usually affected by ambient conditions is numerically studied in this paper. Firstly, the geometry of standard bar is obtained by an optical microscopic 3-D measurement. Then, Solidworks is used to build the 3-D model of standard bar and Gambit is used to mesh the model. Finally, the performance of standard bar under variant ambient conditions is analyzed by Fluent. Compared with the experimental data, the numerical results are found to be quite accurate, and it is found that the ventilation rate increases linearly as temperature rise and decreases non-linearly with the growth of pressure. [ABSTRACT FROM AUTHOR]

In order to enhance the heat transfer effect and improve the energy utilization efficiency of the circular tube under turbulent flow, rhombic and triangular winglet vortex generators are proposed on the basis of rectangular winglet vortex generator. The effects of three vortex generators on flow and heat transfer in the tube are investigated by numerical simulations. The results indicate that, the rectangular and triangular winglets generate two pairs of longitudinal vortices and the triangular winglets generate four pairs of longitudinal vortices due to additional shrinkage regions. The multiple longitudinal vortices increase the mixing between the fluids, raise the temperature in the central region of the tube, and enhance the heat transfer effect. Furthermore, the triangular winglet enhanced tube has the largest direct flow area and the least effect on resistance. The triangular winglet enhanced tube had the best comprehensive performance, followed by the rhombic winglet enhanced tube, and finally, the rectangular winglet enhanced tube. The performance evaluation criterion reached 1.04-1.13, 1.05-1.15, and 1.08-1.21 for the three enhanced tubes in the given flow rate interval. In addition, the effect of inclination angle on the triangular winglet enhanced tube was further investigated, and the results show that the best comprehensive performance of enhanced heat transfer is achieved at an inclination angle of 45°, with a maximum performance evaluation criterion of 1.25. [ABSTRACT FROM AUTHOR]

In response to the problems of high mass and high thermal resistance in traditional cold plate collectors, the author proposes a shaped and efficient micro-channel collector structure design for non-normal temperature control scenarios such as high power, multiple heat sources, and highly non-uniform power density. The author conducted numerical and experimental studies on the laminar heat transfer in a highly efficient micro-channel shaped collector for non-normal temperature control scenarios such as high power, multiple heat sources, and highly non-uniform power density, the results show that: The relative deviation between the simulated and experimental values of the pressure drop of the micro-channel collector using perfluorotriethylamine as the working fluid is within -20%, and the relative deviation between the simulated and experimental values of the surface temperature is within +3 ° C, the predicted trend of the pressure drop and temperature field of the collector is in good agreement with the experimental values, indicating the feasibility of using numerical simulation methods for performance analysis and design optimization of 3-D printed micro-channel collectors. As the flow rate increases, the pressure drop of the collector increases approximately linearly, while the value increase of the total heat transfer coefficient gradually decreases, and increasing inlet temperature or heating power will reduce pressure drop of collector and increase total heat transfer coefficient. The influence of gravity on the pressure drop and total heat transfer coefficient of micro-channel collectors is less than 1. The straight through micro-channel collector has lower pressure drop and stronger heat transfer ability compared to the folded type collector. [ABSTRACT FROM AUTHOR]

In this study, we conducted temperature, pressure, and stress deformation calculations for the tubing of a specific heavy oil thermal recovery well. Subsequently, we used the axial force on the tubing at the depth of the thermal fluid generator as a boundary condition and incorporated it into numerical simulation software to analyze the thermo-fluid-solid coupled mechanical characteristics of the generator under these operating conditions. Our findings indicate that the cooling water within the generator effectively isolates radial heat transfer from the thermal fluid. Moreover, under steam injection conditions, the maximum von-Mises stress in the generator is concentrated at the head-shell weld. [ABSTRACT FROM AUTHOR]

This study adopts the cohesive element technology for the first time to analyze the dynamic evolution process of crack formation and propagation, and to clarify the mechanical mechanism of the O-X failure pattern in the roof. The mechanical behavior of cohesive failure inside the rock is simulated based on the maximum nominal stress criterion, and the Benzeggagh-Kenane (BK) fracture criterion is used to further describe the dependence of fracture energy on the combination of mixed tensile-shear mode. The results show that the O-shaped crack is formed on the top surface of the roof, and delamination occurs along the thickness direction, which coincides with the crack bifurcation position on the bottom surface of the roof. The cross-shaped crack forms on the center of the bottom surface of the roof, and extends towards the four corners at the bifurcation position form a spatial X-shaped crack. [ABSTRACT FROM AUTHOR]

Through the method of numerical simulation, the detection rules of different defect characteristics and the detection effect of detection process parameters on different defects were explored. The optimal detection process parameters for GFRP/NOMEX honeycomb sandwich structure specimens with delaminating, debonding, water accumulation, and glue plugging defects were obtained. Experimental research was carried out to verify its detection effect for actual tests. The result is that the technology under this parameter can get better defect detection effect. [ABSTRACT FROM AUTHOR]

This paper presents a framework for leader-follower type co-operative transportation of an object by multiple humanoid robots or a single robot and a human. The emphasis in this paper is on the hybrid control algorithm and motion generation of the follower robot, while the influence of the leader has been simulated as external force acting on the follower's hands. The presented approach uses impedance controller to provide compliant behaviour of robot arms and it is an extension of our previous work on dual-mode impedance controller for safe humanrobot interaction. Synthesis of the follower's legs and trunk motion is based on the reconfigurable adaptive motion primitives, which are defined as simple, parameterized motion building blocks that can be combined in a sequence or in parallel to generate complex motion. It has been already proven that motion generation, based on reconfigurable adaptive primitives enables the robot to modify gait parameters online, at any time instant, and synthesize dynamically balanced walk. Motion of the follower is based on the reactive approach, where the gait parameters (walking velocity, direction and step length) depend on intensity and direction of the external force vector. Robot end-effectors are compliant in horizontal plain, adapting to the physical guidance of the leader, while being stiff in vertical direction in order to compensate the external force in negative z-direction. The proposed framework has been tested by numerical simulations involving a dynamic robot model. [ABSTRACT FROM AUTHOR]

The paper focuses on the analysis of the neural network mathematical model for temperature and pressure compensation in steam flow measurement, summarizes two types of compensation models suitable for DCS configuration, and introduces the realization of steam flow measurement in ABB Industrial TDCS configuration ways and methods of temperature and pressure compensation. At the same time, the paper uses the scientific neural network intelligent model control method to analyze, optimize, configure and manage the information, improve the operation and management level of the steam system, and realize the optimized operation of the steam system, so as to achieve the purpose of energy saving and consumption reduction. [ABSTRACT FROM AUTHOR]

The K-shaped seal assembly is composed of K-shaped metal seal, high temperature nickel base alloy (GH4169). Its sealing performance directly affects the reliability and stability of flow control system. The 2-D axisymmetric K-shaped metal seal is abstracted as the combination of interference fit model and cantilever beam model. Considering the influence of temperature on the seal, based on the 2-D constitutive relation of elastic medium and heat conduction theory, the theoretical model between contact stress and self variation of K-shaped metal seal ring is deduced by using inverse method. Using ABAQUS thermal structure coupling analysis method, the thermal mechanical coupling finite element model of K-shaped seal assembly is established. The theoretical analytical solution proposed in this paper can be used to calculate the approximate solution of contact stress of radial metal seal under current oilfield conditions, and provides theoretical support for the numerical calculation of thermal stress of radial metal seal. [ABSTRACT FROM AUTHOR]

Temperature from burning wood cribs will be simulated in this paper by sub-grid scale model in fire dynamics simulator. A baseline gas phase uncertainty is determined for simulating wood crib fire spread scenarios. This uncertainty is based on a sensitivity analysis of key input parameters and their subsequent effect on key output variables that are important for fire spread. Effects of different grid systems, computing domains and moisture contents on the predictions were studied first and then used to study the gaseous phase sensitivity. The gaseous phase input variables considered are: Smagorinsky constant, Prandtl number, and Schmidt number. The results show that the predictions for temperature have good agreement with experiment with the values of 0.25, 0.7, 0.4, and 5 for Smagorinsky constant, turbulent Schmidt number, and turbulent Prandtl number, respectively. [ABSTRACT FROM AUTHOR]

Accurately obtaining the temperature distribution of the medium in the shutdown pipe-line of waxy crude-oil has important guiding significance for making maintenance plan and restart plan. The phase transition process of waxy crude-oil involves complex problems such as natural-convection heat transfer, latent heat release, and difficulty in tracing liquid-solid interface. In this paper, the concept and significance of breaking point were proposed. Taking the breaking point and the freezing point as dividing point, a new zonal partition model was established based on the influence of phase change of crude-oil wax crystal on heat transfer mode, with the corresponding governing equations being established for different regions. With the proposed model, the effects of natural-convection on heat transfer, latent heat release, location change of condensate reservoir, heat transfer mechanism, and other key issues in the process of oil phase transition were analyzed. [ABSTRACT FROM AUTHOR]

The paper presents a numerical simulation of two-phase turbulent flow in straight horizontal channels of pneumatic transport with non-circular cross-section. For the granular flow simulation, we have chosen the flow of solid particles of quartz, flour, and ash in the flow of air, which is transporting fluid. During the modeling of the flow, the transported solid particles are reduced to spherical shapes. A correction of the stress model of turbulence is performed by taking into account the influences of the induction of secondary flows of the second order in the gas phase. The full Reynolds stress model was used for modeling the turbulence, and the complete model is used for the turbulent stresses and turbulent temperature fluxes. All numerical experiments were conducted for the same initial flow conditions and a single uniform grid was adopted for all numerical experiments. The flow is observed in a straight channel of a square cross-section and dimensions of sides of 200 mm and the length of 80 Dh. During the simulation, the fineness of the numerical grid was also tested, and the paper shows results of the numerical grid of the highest resolution beyond which the fineness does not influence the obtained results. The paper offers graphics of velocities of the solid particles transported by the transporting fluid (air) along the channel. [ABSTRACT FROM AUTHOR]

Accurate prediction of aerodynamic and thermal environment around a gap has a significant effect on the development of spacecraft. The implicit finite volume schemes are derived and programmed from Navier-Stokes equations. Taking the gap between thermal insulation tiles as an example, a numerical simulation is performed by the finite volume method to obtain the flow characteristic in a gap and then to analyze the heat transfer mechanism. The numerical results are consistent with the experimental ones, which prove the precision of the method used in this paper. Furthermore, the numerical results reveal that the heat convection plays a leading role in heat transfer around a gap. [ABSTRACT FROM AUTHOR]

The coal seam gas recovery in deep reservoirs often meets high temperature. The change of temperature can greatly influence gas sorption, and couples heat transfer with coal deformation and gas-flow. This paper modifies the conventional Langmuir adsorption equation into a non-isothermal adsorption equation with a set of experimental data. After then, a fully coupled thermo-hydro-mechanical model of coal deformation, gas-flow and heat transfer is established. By using a finite element approach of COMSOL multi-physics, a numerical simulation of coal seam gas recovery from high temperature reservoir is subsequently implemented. The results show that the gas pressure and temperature decrease with production time and increase with the distance from production well, the reservoir permeability decreases with production time due to the compaction of increasing effective stress to coal fracture network, the cumulative gas production increases with production time exponentially whereas the production efficiency decreases negative exponentially, that the gas production in earlier 10 years accounts for 80% of the total production in 30 years. Our fully coupled thermo-hydro-mechanical model can improve the current understanding of coal seam gas recovery from high temperature reservoirs. [ABSTRACT FROM AUTHOR]

This paper provided a numerical simulation of fluid dynamics in the chemical vapor reactor for nanoparticle synthesis. Standard k-e turbulence equation and eddy-dissipation model with standard wall function were used to investigate the reaction process of turbulent diffusion for alumina production. Here the temperature and the operating conditions are discussed. Numerical results show that the model can well describe synthesis of nanometer alumina. The chemical reactions for alumina by this reactor are mainly concentrated in the range of 200 mm after the nozzle. The materials are completely mixed after 400 mm in the reactor. [ABSTRACT FROM AUTHOR]

Addressing the growing severe heat-generation and temperature-rise issues of the civil aircraft hydraulic system, this paper proposes a thermal dynamic model and thermal management strategies for the system within full mission profile. Firstly, a new thermal dynamic modeling towards general hydraulic components is conducted. Secondly, thermal dynamic governing equations are derived. Then a thermal management mechanism of the system is proposed. The conducted research is prerequisite to future numerical simulation of the thermal dynamic characteristics, evaluation and improvement of thermal management strategies for the system. [ABSTRACT FROM AUTHOR]

In order to accelerate the numerical simulation and optimization of gas turbine-related configurations, a source based computational fluid dynamics (SCFD) approach is developed for flow and heat transfer simulations. Different sources depending on the fluid porosity at each grid node in the computational domain are introduced to the continuity, momentum, energy and turbulence model equations, so that both the fluid and solid regions can be solved as one region. In the present paper, test cases including a ribbed channel and a winglet shrouded turbine cascade with tip injection are investigated using the SCFD and CFD with body-fitted meshes. Impacts of grid clustering and turbulence model equation sources on the SCFD precision are examined. Numerical results show that the SCFD predicts consistent aerothermal performance with the fluid dynamics with body-fitted meshes and experiments. The validated SCFD scheme is then employed in a response surface optimization of tip jet holes on the winglet shroud tip. A jet arrangement with the minimum energy loss and injection mass-flow rate is obtained, indicating that source based predictions can be applied to the preliminary aero-thermal design of turbine blades. [ABSTRACT FROM AUTHOR]

This paper proposes an effective method to predict the thermal conductivity of plain woven blended fabric to optimize woven fabric structure, and to evaluate thermal comfort. The unit cell model of fabric is established for numerical simulation of heat transfer through thickness. The thermal conductivity of blended yarns is calculated by a series model. The temperature and heat flux distributions are verified experimentally. [ABSTRACT FROM AUTHOR]

Based on the basic principles and improved algorithms of the smoothed particle hydrodynamics method, a corresponding surface tension model and latent heat model are proposed for the heat exchange phase transition problem of droplets impinging on a low temperature wall surface. This research establishes a novel smoothed particle hydrodynamics model of the impinging wall of droplets accompanied by the phase transition process. This work also includes simulations covering the spreading flow and phase transition process of droplets under different impingement regimes. Moreover, the icing patterns of the droplet impingement spreading process are provided and a comparative analysis with related experimental results. The improved smoothed particle hydrodynamics model is verified by experiments and its ability to solve droplet impingement icing problems. [ABSTRACT FROM AUTHOR]

This paper presents one of the possible hazardous situations during transportation of gas through the international pipeline. It describes the case when at high-pressure gas pipeline, due to mechanical or chemical effect, cracks and a gas leakage appears and the gas is somehow triggered to burn. As a consequence of heat impingement on the pipe surface, change of material properties (decreasing of strength) at high temperatures will occur. In order to avoid greater rapture a reasonable pressure relief rate needs to be applied. Standards in this particular domain of depressurizing procedure are not so exact (DIN EN ISO 23251; API 521). This paper was a part of the project to make initial contribution in defining the appropriate procedure of gas operator behaving during the rare gas leakage and burning situations on pipeline network. The main part of the work consists of two calculations. The first is the numerical simulation of heat radiation of combustible gas, which affects the pipeline, done in the FLUENT software. The second is the implementation of obtained results as a boundary condition in an additional calculation of time resolved wall temperature of the pipe under consideration this temperature depending on the incident flux as well as a number of other heat flow rates, using the Matlab. Simulations were done with the help of the “E.ON Ruhrgas AG” in Essen. [ABSTRACT FROM AUTHOR]

The paper considers two-phase gas-solid turbulent flow of pneumatic transport in straight horizontal channels with a non-circular cross-section. During turbulent flow, a specific flow phenomenon, known as secondary flow, occurs in these channels in the cross-sectional plane. The existence of strong temperature gradients in the cross-sectional plane of the channel or the cases of curved channels result in the appearance of the secondary flow of the first kind. However, in straight channels with a non-circular cross-section, in the developed turbulent flow mode, a secondary flow, known as Prandtl's secondary flow of the second kind, is induced. The paper presents a numerical simulation of a developed twophase turbulent flow by using the PHOENICS 3.3.1 software package. Reynolds stress model was used to model the turbulence. The paper provides the data on the changes in turbulent stresses in the channel cross-section as well as the velocities of solid particles transported along the channel. [ABSTRACT FROM AUTHOR]

The paper proposes a new air-jet spinning method for the preparation of continuous twisted nanofiber yarns. The nozzle-twisting device is designed to create the 3-D rotating airflow to twist nanofiber bundles. The airflow characteristics inside the twisting chamber are studied numerically. The airflow field distribution and its effect on nanofiber yarn spinning at different pressures are also discussed. [ABSTRACT FROM AUTHOR]

This paper studies numerically the two-phase flow in the single-bubble electrospinning process by solving the modified Navier-Stokes equations under the influence of electric field, and the interface between the twofluids has been determined by using the volume of fluids method. A realizable k-ε model is used to model the turbulent viscosity. The numerical results offer in-depth insight into physical understanding of many complex phenomena which cannot be fully explained experimentally. [ABSTRACT FROM AUTHOR]

Fractional calculus can always exactly describe anomalous diffusion. Recently the discrete fractional difference is becoming popular due to the depiction of non-linear evolution on discrete time domains. This paper proposes a diffusion model with two terms of discrete fractional order. The numerical simulation is given to reveal various diffusion behaviors. [ABSTRACT FROM AUTHOR]

In this paper, a solution method for the temperature distribution of rectangular test specimen with a high-speed heat air-flow passing through is proposed based on the heat transfer theory and numerical calculation, and the feasibility of temperature prediction method is validated. Firstly, the partial differential equations to describe the average temperature in the section of the hot air-flow and the specimen are established and the solving method using MATLAB solver is proposed. Then, based on heat transfer conduction equation and the average temperature, the temperature distribution at different point in each section is calculated. The comparison between numerical computation and experiment shows that two results are in good agreement, which verifies the correctness of the presented prediction method of the temperature distribution of the specimen. [ABSTRACT FROM AUTHOR]

In this paper a radiator heating system of a building is considered. For the purpose of the heating system optimization, a mathematical model of the system is developed. The linear quadratic algorithm with integral action is proposed and analyzed. This solution has proven to be expensive. Further analysis of the model is done and a reduction of the order of the system is proposed. An inverse-based controller design approach for minimum-phase first order system is used to provide realizable controller in the form of proportional integral controller. Optimal parameters of the control algorithm parameters have been chosen by integral of time absolute error criterion, and also by metaheuristic optimization. According to the real heating demand, a simulation of the plant is performed. Proposed controllers were tested by numerical simulation for a typical winter day for geographical region of the building. It is shown that advanced performance can be achieved with optimized control systems, and that by controller optimization a significant reduction of the energy consumption is obtained without losing the indoor comfort. This has also proved to be more economical solution. [ABSTRACT FROM AUTHOR]

This paper addresses the complex component evolution and silicon dynamic deposition characteristics in the traditional Siemens reactor. A two-dimensional heat and mass transfer model coupled with a detailed chemical reaction mechanism was developed. The distributions of temperature, velocity, and concentration are presented in detail. The influencing factors (such as feeding mole ratio, inlet velocity, base temperature and reactor pressure) on the molar concentration evolutions often major components and silicon growth rate were obtained and analyzed. Results show that base temperature is main influence of HCl mole fraction. In order to get more growth rate of silicon and better silicon quality, the complex operating parameters need to be reasonably designed on collaborative optimization. [ABSTRACT FROM AUTHOR]

At present, the rural population of China is large. The rural population accounts for about 50% of the total population in Heilongjiang Province, which is located in cold region. The winter is cold in severe cold region, for example, the average outdoor temperature in winter is about -25 °C in Daqing which is located in Heilongjiang Province, the indoor residential thermal environment is poor, people living there are uncomfortable. The existing rural residential building was researched in Daqing of Heilongjiang and the study of the indoor thermal environment was carried out. In this paper, the numerical simulation method is used to study the changes of indoor temperature field before and after adopting the wall insulation of existing house. The results show that the thermal environment of the existing rural house without wall insulation can not satisfy the requirements of human comfort, and the bedroom temperature is about 15 °C, and the temperature of the entrance hall is about 11 °C. However, the insulation of the building envelope has an obvious effect on the indoor thermal environment, and the temperature of the bedroom and the entrance hall increase about 5 °C and 3 °C with wall insulation, respectively. [ABSTRACT FROM AUTHOR]

The present work is a contribution to study of convective heat transfer coefficient inside a rectangular channel with corrugated walls. Triangular, square, and rectangular shaped configurations were studied for a range of geometric parameters during simulation. The Navier-Stokes equations were numerically solved using the finite volume method through the EasyCFD_G package code in its V.4.1.0 version. With prescribed temperatures and velocities, the model predicts the behavior of the air-flow inside the device. The temperature and velocity distributions are first predicted. From these distributions, the convective heat transfer coefficients along the surface of the objects placed inside the system are determined. Also, from the pressure distribution, the pressure drops along the channel are predicted. The results show that the triangular corrugated-shaped configuration with h = 5 cm and α = β = 60° enable to obtain the best value of convective heat transfer coefficient on the surface of the objects which is 2.70 W/m2°C resulting in a pressure drop of 0.11 Pa, while for parallel-plate channel configuration this same coefficient is 1.12 W/m2°C. The energy balance enabled to conclude that the energy gain by convection air/objects is superior to the air pump energy to overcome the pressure drop. [ABSTRACT FROM AUTHOR]