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Investigation still on board for finding the best techniques to develop the thermal and hydraulic performance of the heat exchanger. One of the useful, practical methods for finding the modification is the numerical analysis. This numerical analysis was obtained by modelling and simulation using ANSYS FLUENT software. In this present work five elements were modelled and simulated of three different configuration models, helical tape, rectangular and triangular straight strip inserts were inserted inside the inner pipe. This simulation was employed according to the working operation conditions of the real practical double pipe heat exchanger. The results show that, the helical tape configuration demonstrated the effective enhancing technique of the heat transfer, which is improving the thermo-hydraulic performance of this type of heat exchanger in this study. According to this work, the technique of studying numerically the design enhancement of the heat exchanger can produce an excellent result and gives a good recommendation to transfer it into practical work. [ABSTRACT FROM AUTHOR]

The method of thermal diagnostics of friction (TDF) has been developed in detail for radial sliding bearings with rotary motion of the shaft, which makes it possible to determine the friction force from temperature data.The possibility of determining the frictional moment by measuring the temperature is theoretically shown in the case of the swinging motion of the shaft using a two-dimensional mathematical model of the thermal process. The use of a two-dimensional model limits the use of the TDF method for solving practical problems. In this paper a three-dimensional model of the thermal process is proposed, taking into account the rotating speed of the shaft for a sliding bearing operating in a reciprocating-rotational mode. Taking into account the speed of the shaft movement leads to a significant increase in the calculation time, which is not always desirable for TDF based on solving the inverse problem of heat transfer. Determining the conditions under which it is possible to disregard the speed of the shaft in the thermal process model is an urgent problem. The method for determining the kinematic conditions for accounting for the speed of the shaft in the mathematical model of the thermal process is proposed on the basis of a numerical analysis of the unsteady three-dimensional temperature field in a radial self-lubricating sliding bearing. The results obtained can be used for TDF in real sliding bearings. [ABSTRACT FROM AUTHOR]

A gas-phase deposition is one of the types of additive technologies and is a process of applying a film or coating to the cooled surface, that is, a continuous layer of material that has, among other things, a nanocrystalline structure. Currently, the development of this and other additive technologies has made it possible to apply a variety of coatings with different properties. In most works devoted to the deposition numerical simulation, the features of gas heat exchange with the surface are not taken into account, while the temperature of the surface on which deposition occurs is one of the fundamental factors determining the film structure. In this paper, a numerical model of heat transfer during gas-phase deposition of a material on a cooled curved substrate is constructed, taking into account the specifics of heat exchange of the gas medium. A numerical analysis of the mathematical model is performed, and the influence of various heat transfer mechanisms on the temperature distribution in the substrate being built up is shown. [ABSTRACT FROM AUTHOR]

The effect of the water operating pressure on the external heat losses value of the shell-and-tube heat exchanger by using the heat loss recovery systems based on the Rankine steam cycle has been analyzed in the present paper. A comparative analysis of the effectiveness of insulating various sections of the outer surface of the heat exchanger casing was also carried out. The choice of the heat exchanger was determined by the design simplicity, the ability to withstand high pressures and temperatures, as well as by the fact that its design makes it easier to carry out thermal insulation. The analysis of the heat transfer processes in regenerative HE was conducted on the basis of the equations contained in the ANSYS Fluent package. When modeling heat exchange processes, the following boundary conditions have been adopted: the hot air temperature at the inlet Th is equal to 600 °C (the first option) and 800 °C (the second option); the water temperature at the inlet Tw is 16 °C; the ambient temperature Ta is 20 °C. The heat transfer coefficient α between the environment and outer surface of the HE is considered as constant. The obtained results revealed that heat losses significantly decrease only when the first section is insulated in 25% of the casing surface. After isolating 50% of the casing surface, the heat losses amount remained largely unchanged. It can also be concluded that with an increase in excess water pressure, the heat losses value decreases from ∼40% to ∼8% (at the inlet gas temperature of 800 °C) and from ∼34% to ∼7% (at the inlet gas temperature of 600 °C), when the casing surface insulating degree changes from 0% to 100% and water pressure varies from 1 to 150 atmospheres, correspondingly. This is due to the fact that the water pressure increase results in increasing the boiling point and the liquid water heating area with a high heat capacity. The latter increases the heat flux perceived by the water from the hot gas, and therefore leads to the external heat loss decrease. [ABSTRACT FROM AUTHOR]

Recent methods of numerical analysis of both direct and inverse heat transfer problems combine the partial knowledge of analytical or semianalytical solutions with advanced computational algorithms. Numerous approaches rely on the engineering experience with linear or ad hoc linearized initial and boundary value formulations, together with their incomplete experimental validation, avoiding their proper non-trivial mathematical verification. This paper demonstrates typical difficulties of such verification for a direct and inverse variant of a model problem of heat conduction with temperature-dependent thermal conductivity and diffusivity, together with comments to potential generalizations and practical applications of its results. [ABSTRACT FROM AUTHOR]

A new exact solution of the two-dimensional Oberbeck-Boussinesq equations has been found in this paper. The solution is found in the case of the nonuniform distribution of velocities and a linear heat source at the upper boundary of an infinite layer of a viscous incompressible fluid. Analysis of polynomial solutions describing the natural fluid convection is presented. The existence of points at which hydrodynamic fields vanish inside the fluid layer is demonstrated. [ABSTRACT FROM AUTHOR]

This paper presents the numerical model of the measuring stand - the wind tunnel, in which is fixed the cylinder with cooling inlet oscillating stream. The aim of this work is the juxtaposition and comparison of characteristic values concerning the oscillating turbulent flow around cylinder, obtained from the experiment conducted in the wind tunnel at the Institute of Thermal Machinery, Czestochowa University of Technology with the data obtained as a result of numerical modeling of unsteady flow phenomena with heat transfer processes. Model discussed in this paper was created using a commercial program ANSYS FLUENT, that is used for mathematical modeling of flow and heat transfer processes. The expected outcome of this study is that it is possible in a way that doesn't require large expenditures of time, numerical modeling a similar stand, which greatly facilitated by further research into the very large issue of unsteady flows. [ABSTRACT FROM AUTHOR]

In this paper we focus on the second unit of multipass amplification of the cryogenic diode-pumped high power laser system operating at 1 kHz repetition rate. Thermal fields in the cooling system of the amplifier were calculated and compared with experimental data. Numerical algorithm based on 3+1D heat transfer equation is proposed. The results of modeling are discussed and analyzed. [ABSTRACT FROM AUTHOR]

In this paper heat transfer and fluid flow in a two-dimensional lid-driven square cavity with discrete source-sink is studied. A finite element method is used for solving the governing equations. The parametric studies are Darcy number in the range of 10-5 to 10-1, Grashof number in the range of 10³ to 105, Reynolds number constant at 100 and Prandtl number constant at 0.71. Galerkin weighted residual method is used to perform numerical solutions. The streamlines, isotherms, average Nusselt number, and average temperature of the fluid in the enclosure are presented for the dimensionless parameters. It is found that the heat transfer rate is decreased for decreasing of Darcy number. [ABSTRACT FROM AUTHOR]

Thermal Energy Storage (TES) systems are central elements of various types of power plants operated using renewable energy sources. Packed bed TES can be considered as a cost-effective solution in concentrated solar power plants (CSP). Such a device is made up of a tank filled with a granular bed through which heat-transfer fluid circulates. However, in such devices, the tank might be subjected to catastrophic failure induced by a mechanical phenomenon known as thermal ratcheting. Thermal stresses are accumulated during cycles of loading and unloading until the failure happens. This paper aims at studying the evolution of tank wall stresses over granular bed thermal cycles, taking into account both thermal and mechanical loads, with a numerical model based on the discrete element method (DEM). Simulations were performed to study two different thermal configurations: (i) the tank is heated homogenously along its height or (ii) with a vertical gradient of temperature. Then, the resulting loading stresses applied on the tank are compared as well the response of the internal granular material. [ABSTRACT FROM AUTHOR]

This paper presents a numerical analysis of unconstrained melting of high temperature(>1000K) phase change material (PCM) inside a cylindrical container. Sodium chloride and Silicon carbide have been used as phase change material and shell of the capsule respectively. The control volume discretization approach has been used to solve the conservation equations of mass, momentum and energy. The enthalpy-porosity method has been used to track the solid-liquid interface of the PCM during melting process. Transient numerical simulations have been performed in order to study the influence of radius of the capsule and the Stefan number on the heat transfer rate. The simulation results show that the counter-clockwise Buoyancy driven convection over the top part of the solid PCM enhances the melting rate quite faster than the bottom part. [ABSTRACT FROM AUTHOR]

In this paper, the problem of boundary layer flow and heat transfer in a viscous fluid over a stretching sheet with viscous dissipation and internal heat generation is studied. Thermal boundary condition on the surface that is prescribed surface temperature (PST) is considered. The governing nonlinear partial differential equations are transformed into nonlinear ordinary differential equations by applying the similarity transformations. The obtained nonlinear ordinary differential equations are reduced to the system of first order ordinary differential equations. Then the system of first order ordinary differential equations is solved numerically using the Keller-box method. Results are presented in figures and discussed in details for the temperature profiles and the temperature gradient for some values of the Prandtl number, Eckert number and heat/source sink parameter. [ABSTRACT FROM AUTHOR]

In this paper, flow and heat transfer over a stretching and shrinking sheet with slip and convective boundary condition were investigated. The governing boundary layer equations are transformed into ordinary differential equations and solved by using the shooting technique. The stretching and shrinking parameters, dimensionless slip parameter, Biot number and constant mass suction parameter are used to generate the numerical results. The results show that the dual solutions exist for suction case. The obtained results also indicate that the mass suction and slip processes delay the boundary layer separation. [ABSTRACT FROM AUTHOR]

Thermographic nondestructive evaluation is quick and effective in detecting damage particularly for composite structures. Pulse thermographic nondestructive evaluation (TNDE) technique can potentially provide information on defect dimensions, such as the depth at which the defect is located. However, there are a number of extraneous variables that affect the signal obtained during these tests, such as non-uniformity in the heat pulse applied and differences in the emissivity of the surfaces from specimen to specimen. In addition, the identification of defect free areas in the image is a challenge. As in other NDE procedures calibration specimens would be of help, but calibration specimens corresponding to complex damage states in composite materials are difficult to fabricate. Results from validated numerical simulations can complement calibration specimens. However, the thermo-mechanical properties of the test object as well as the amount of heat energy absorbed in the field tests are not readily available for such models. This paper presents an extension of the thermographic signal reconstruction (TSR) procedure in which the temperature and the time scales are respectively normalized with equilibrium temperature and the break time. A benefit of such normalization is the ability to directly measure the defect depth as a fraction of plate thickness. In order to implement this normalization procedure, sound zone profile definition is required. A new approach for determining sound zone profile has been developed. Finally, determination of sound zone is affected by non-uniform heating, and a method of minimizing the effects of non-uniform heating is proposed. The performance of these new approaches on actual experimental results are presented. [ABSTRACT FROM AUTHOR]

In this paper, the influence of non-equilibrium CO2 kinetics on gas dynamic parameters and transport properties in a viscous shock layer near blunt bodies is studied. This problem is important for accurate prediction of macroscopic parameters and heat transfer near a space vehicle re-entering the Mars atmosphere. The hypersonic flow of reacting CO2/CO/O2/C/O mixture is studied numerically using the accurate kinetic theory models for transport properties and chemical reaction rates proposed in our previous papers on the basis of three-temperature vibrational distributions. The kinetic theory algorithms were implemented directly to the computational fluid dynamics solvers. The transport properties and gas dynamic parameters in 2-D viscous shock layer near blunt bodies of different shape are studied for various test cases under Mars re-entry conditions. The influence of non-equilibrium effects on gas flow parameters and heat transfer is discussed; a quite different structure of a shock layer is found for various body shapes. The comparison with the results obtained using more simple models for CO2 kinetics, transport coefficients, and reaction rates is shown. [ABSTRACT FROM AUTHOR]

This paper presents numerical study of flow behavior from a heated concentric annulus cylinder at various Rayleigh number Ra, Prandtl number Pr while the aspect ratio is fixed to 5.0 of the outer and inner cylinders. The Finite Different Lattice Boltzmann Method (FDLBM) numerical scheme is proposed to improve the computational efficiency and numerical stability of the conventional method. The proposed FELBM applied UTOPIA approach (third order accuracy in space) to study the temperature distribution and the vortex formation in the annulus cylinder. The comparison of the flow pattern and temperature distribution for every case via streamline, vortices and temperature distribution contour with published paper in literature were carried out for the validation purposes. Current investigation concluded that the UTOPIA FDLBM is an efficient approach for the current problem in hand and good agreement with the benchmark solution. [ABSTRACT FROM AUTHOR]

This paper deals with the mathematical model of a steady flow of a heat-conductive incompressible viscous fluid through a spatially periodic plane profile cascade. The corresponding boundary value problem is reduced to one spatial period. We prove the existence of a weak solution of a coupled problem, with various boundary conditions on the parts of the boundary. Particularly, the condition on the outflow is a variant of the so called "do nothing" boundary condition. [ABSTRACT FROM AUTHOR]

The simultaneous movement of liquid water, water vapor, and heat in the vadose zone plays a critical role in the overall water and energy balance of the near surface environment. Moisture near the soil surface is influenced by evaporation, precipitation, liquid water flow, and water vapor flow, most of which are strongly coupled. The demand for mathematical models that take into account spatial and temporal scales for the shallow soil are now-a-days more imperative given that: (a) the critical role that such processes play in the global water and energy balance; (b) the interplay between spatial and temporal scales in the near surface region is not well understood. The new contributions in this paper are: the coupled model is revisited and some modifications are proposed aiming to represent the surface/subsurface interaction more accurately; the spatial upscaled coupled model is presented. The models are validated by comparing numerical results between the fine-scale and upscaled models and data for both, moisture and temperature. The field data comes from a detailed controlled experiment from Riverside-CA, with measurements taken at 2, 7 and 12 cm below the surface. [ABSTRACT FROM AUTHOR]

The simultaneous movement of liquid water, water vapor, and heat in the vadose zone plays a critical role in the overall water and energy balance of the near surface environment. Moisture near the soil surface is influenced by evaporation, precipitation, liquid water flow, and water vapor flow, most of which are strongly coupled. The demand for mathematical models that take into account spatial and temporal scales for the shallow soil are now-a-days more imperative given that: (a) the critical role that such processes play in the global water and energy balance; (b) the interplay between spatial and temporal scales in the near surface region is not well understood. The new contributions in this paper are: the coupled model is revisited and some modifications are proposed aiming to represent the surface/subsurface interaction more accurately; the spatial upscaled coupled model is presented. The models are validated by comparing numerical results between the fine-scale and upscaled models and data for both, moisture and temperature. The field data comes from a detailed controlled experiment from Riverside-CA, with measurements taken at 2, 7 and 12 cm below the surface. [ABSTRACT FROM AUTHOR]

Analysis of heat and mass transfer in most engineering applications relies on the principles of classical thermodynamics, supplied by simplified constitutive relations, involving effective macroscopic material characteristics, as Fourier, Fick, etc. laws. The validity of modelling and simulation results related to real physical processes is determined by the reliable identification of such characteristics. Introducing a rather simple model problem, the paper demonstrates a common approach to the development of quick and robust identification algorithms, based on the conjugate gradient version of the least squares approach. Several generalizations, including still open problems, are sketched and referenced to related research results, as well as to special types of numerical applications from engineering practice. [ABSTRACT FROM AUTHOR]

In this paper we discuss the effect of sharp property variations on the turbulent heat transfer in fluids close the critical point. The governing equations for this flow regime are discussed, a short description of the numerical tools that have been developed to study these flows is given. Finally, some results for supercritical heat transfer in developing turbulent pipe flow are presented. [ABSTRACT FROM AUTHOR]

In this paper the impurity distribution is computed in an axis-symmetric (2D) domain, which represents the meniscus and a part of the capillary channel. The model takes into account the pulling rate, thermal convection, molecular diffusion and thermo diffusion. Numerical illustration is given for Al doped cylindrical Si tube wall and the contribution of each effect is evaluated. The main novelties consist in the fact that the axis-symmetric (2D) domain is obtained by a prior computation using the Young-Laplace capillary surface equation and the heat transport equation as well in the inclusion of the thermo diffusion effect in the impurity distribution equation, respectively. [ABSTRACT FROM AUTHOR]

In this paper, the steady boundary layer flow and heat transfer over a stretching sheet with convective boundary conditions are studied, where the heat is supplied to the convecting fluid through a bounding surface with a finite heat capacity. The nonlinear boundary layer equations are transformed into ordinary differential equations which are then solved numerically via the Keller-box method. Numerical solutions are obtained for the wall temperature, the local heat transfer coefficient for various values of the Prandtl number and the conjugate parameter. The effect of these parameters is discussed and it was found that the boundary layer thickness increases as conjugate parameter increases but opposite trend is observed for the increasing value of Pr. [ABSTRACT FROM AUTHOR]

In this paper, numerical investigation using ethylene glycol (EG) as a base fluid with diamond and SiO2 as the coolants with nanoparticle volume fractions (φ) ranged from 0.1 % to 2 % on automobile flat tube plain fin compact heat exchanger (CHE) is conducted. The convective heat transfer coefficient in the developing regions along the flat tubes with the nanofluid flow showed marked improvement over the base fluid (0 %). Quantitative results of the heat transfer enhancement of CHE with increasing volumetric concentrations of nanofluids at various Reynolds numbers are presented. [ABSTRACT FROM AUTHOR]

This paper presents a numerical investigation on heat transfer in power-law fluids aligned with a semi-infinite plate in the presence of viscous dissipation and radiation. The effects of power-law viscosity on temperature field are taken into account by assuming that the thermal diffusivity varies as a function of velocity gradient. Since the problem is very complex to solve analytically, a similarity transformation based on the least square approximation principle and shooting technique may be a considerable approach. The effects of generalized Prandtl number, viscous dissipation and radiation on the heat transfer are tabulated. [ABSTRACT FROM AUTHOR]

A numerical study is performed for the oscillating flow and heat transfer in porous media using the lattice Boltzmann method (LBM), which is a new method of computational fluid dynamics. In this paper, the structure of regenerator's packing is assumed as many cylinders with regular arrangements. The oscillatory flow in the channel is driven by a periodic pressure wave. Through the numerical simulation, the parameters including pressure, velocity and temperature variations are presented. There are some little vortexes at the back area of solid cylinder. The moving working gas show the clear zero velocity profile in the flow channel. The thermal diffusivity ratio between solid and fluid have great influence on heat transfer. [ABSTRACT FROM AUTHOR]

In this paper we show a detailed verification of an analytical thermal diffusivity model using finite element simulations. The real pore morphology for the simulation models are obtained by computed tomography measurements. The heat transfer by conduction is simulated in transient analyses. The thermal diffusivity values are calculated from the temperature field on the front (reflection mode) and on the back sides (transmission mode). Investigations show that the analytical model correlates well with the thermal diffusivity values calculated in transmission mode. Furthermore, the simulations show a discrepancy in the reflection mode measurements due to the stronger influence of the pore morphology. These findings are similar to those seen in pulsed thermography experiments. In conclusion, the analytical thermal diffusivity model allows a precise quantification of porosity in carbon fiber reinforced polymer structures using transmission mode measurements. [ABSTRACT FROM AUTHOR]

Numerical simulation became an important tool in optimization of energy consumption in buildings. The dimensioning of heating/cooling systems must supply the necessary energy in order to reach the standard indoor environmental conditions, but, on the other hand, energy-savings measures should not sacrifice people's comfort and health. In this paper, the temperature distribution in a test geometry corresponding to a building at real dimensions is numerically calculated for different environmental conditions, specific to summer and winter seasons. The influence of different types of boundary conditions is investigated. The possibility to control the indoor temperature field using heat sources is also discussed. The computations were performed using CrysVUn software, special designed for modeling of heat transfer in complex geometries by conduction, convection and radiation. [ABSTRACT FROM AUTHOR]

This paper presents the evaluation of several solid wall boundary conditions when used in the numerical solution of the Boltzmann equation using the finite-difference/finite-volume methods. Five solid wall boundary conditions are considered: (a) adsorption, (b) specular reflection, (c) diffuse reflection, (d) Maxwellian reflection, and (e) adsorptive Maxwellian reflection. The boundary conditions are applied on a two-dimensional discretized velocity space mesh. Methods for applying the same boundary conditions on a three-dimensional velocity space grid are also presented. The boundary conditions are implemented for the numerical solution of the hypersonic rarefied flow over a flat plate using a three-dimensional generalized Boltzmann equation (GBE) solver. The derivatives that contribute to heat transfer and skin friction at the solid boundary are calculated and compared. Recommendations for further evaluation of the boundary conditions are made. [ABSTRACT FROM AUTHOR]

This paper reports an analytical and numerical study of the combined Soret and thermosolutal effects on natural convection in a shallow rectangular cavity filled with a binary mixture. Neumann boundary conditions for temperature and concentration are applied to the horizontal walls of the enclosure, while the two vertical ones are assumed impermeable and insulated. For convection in an infinite layer, analytical solutions for the stream function, temperature and concentration fields are obtained using a parallel flow approximation in the core region of the cavity and an integral form of the energy and constituent equations. The critical Rayleigh numbers for the onset of supercritical and subcritical convection are predicted explicitly by the present model. Numerical solutions of the full governing equations are obtained for a wide range of the governing parameters. A good agreement is observed between the analytical model and the numerical simulations. [ABSTRACT FROM AUTHOR]

Modeling studies are preformed to investigate the plasma and heat transfer characteristics of a low power argon arcjet thruster. Computed temperature, velocity, static pressure, and Mach number distribution in arcjet thruster under typical operating condition are presented in this paper. It shows that the performance data from numerical modeling results are basically consistent with the experimental measured values. [ABSTRACT FROM AUTHOR]

The safety and the thermal comfort of victims and firefighters are important in the building fires, which are a little dependent on the occupant fatalities. In order to investigate the effects of the dangerous environment on human body in fires, numerical calculation of the heat transfer and human thermoregulation are presented in this paper. The numerical manikins coupled with human thermal models were proved as powerful tools for visualizing thermal comfort. The two-node model by Gagge and multi-code thermoregulation models were investigated, and the Gagge’s model was coupled with the CFD for high-temperature environment simulation, with which a numerical manikin was built. During the simulation, temperatures of skin and core compartment of Computer Simulated Person (CPS) were recorded respectively, and the Predicted Mean Vote index values were counted. The thermal load on skin is much higher than neutral cases and the skin can be burnt in minutes if no protection and heat abstraction methods were introduced. Though existing models can predict thermal comfort in general indoor environment, they are not suitable in predicting the thermal comfort with high-temperature cases. It was suggested that more research combining CFD coupling thermoregulation models with thermal manikin experiment are needed. [ABSTRACT FROM AUTHOR]

Electromagnetic elasto-plastic dynamic response of a conductive plate in a magnetic pulse field are studied in this paper, the influence of the strain rate effect is investigated for the electromagnetic elasto-plastic deformation of the conductive plate. Basic governing equations are derived for electromagnetic field (eddy current), the elasto-plastic transient dynamic response and the heat transfer of a conductive rectangular plate, and then an appropriate numerical code is developed based on the finite element method to quantitatively simulate the magneto-elasto-plastic mechanical behaviors of the conductive rectangular plate. The Johnson-Cook model is employed to study the strain rate effect and temperature effect on the deformation of the plate. The dynamic response is explained with some characteristic curves of deformation, the eddy current, and the configurations, the temperature of the conductive plate. The numerical results indicate that the strain rate effect has to be considered for the conductive plates, especially for those with high strain rate sensitivity. Comparison of the influence of the temperature effect on the deformation of the plate with that of the strain rate effect shows that the influence of the temperature effect on the deformation of a plate is not significant. [ABSTRACT FROM AUTHOR]

The plasma temperature for laser propulsion can reach above 10000 K, hence, the thermal-mechanical impact and damage of thrusters will be a key problem in future. In this paper, numerical simulations for Myrabo’s annular-focusing lightcraft were carried out both for single and multiple laser pulses. The results indicate that the main factor causing temperature increase is the transmission absorption, the second one is the thermal radiation, and the convection heat transfer is small. The 100 pulse simulation result shows that the mechanical damage starts at the 65th pulse and the heat melt damage begins at the 91st pulse, and finally at about 100 pulses the thruster structure will be disintegrated with partially fracture and melting. The computational results explain the experimental phenomena well. [ABSTRACT FROM AUTHOR]

An upgrade of the CICC facility at the ENEA Superconductivity laboratories for the characterization of superconducting long length wound conductors in forced He flow cooling, has begun. In this framework a considerable effort has been spent for the design of two appropriate gas-cooled current leads for a 30 kA insert. Indeed, several geometrical and operational constraints have been considered due to the re-use of the pre-existing cryogenic plant and background magnet. In particular, to limit the overall length of the leads and the amount of cooling gas to be employed, a hybrid resistive/HTS configuration has been conceived. It consists of a copper bar, with an adequate heat exchanger, from room temperature down to 40 K and an HTS BSCCO part from 40 K down to 5 K. Two helium inlets are foreseen for the lead cooling: one at 5 K at the bottom edge, in parallel to the background magnet refrigerant line, and one at 16 K in the joint between the resistive and the HTS parts. In this paper the description of the numerical analyses performed for the optimal design of the leads are discussed. [ABSTRACT FROM AUTHOR]

Numerical modeling of heat transfer during solidification has become widespread in the foundry industry. This is because it is possible to investigate the effects of adjustment to the casting variables on final casting quality, without having to do costly trial-and-error experiments. After selecting a suitable mathematical model, one has to choose an appropriate discretization method. If the grid is very fine, each type of method yields the same solution. However, some methods are more suitable to some classes of problems than others. The main objective of this paper is to demonstrate the advantages of using a block unstructured grid in combination with a generalized curvilinear formulation in a casting scenario and compare the performance of two discretization methods, finite differences (FD) and finite volume (FV). The validation of the numerical procedure is done by comparison with measurements which experimental set up is also described. A very good agreement of both numerical methods were verified with a slightly advantage for the finite volume method. Block unstructured grids works well with both discretization methods, allows obtain any physical feature in specific positions of the domain and is suitable for parallel computation; in combination with a generalized curvilinear formulation allows avoid geometric complexities and the development of more efficient algorithms. [ABSTRACT FROM AUTHOR]

In this paper a numerical investigation has been carried out to define average Nusselt number on a convex heated curved surface entry of an adiabatic channel. For channels with a convex heated surface, where the increase in flow cross sectional area decelerates the flow (adverse pressure gradient) while buoyancy accelerates the flow, separation is observed near the heated surface. The effects of Reynolds number, Grashof number, and separation on average Nusselt number is discussed for a fixed value of R/L. [ABSTRACT FROM AUTHOR]

Numerical modeling of the glass forming processes requires the accurate knowledge of the heat exchange between the glass and the forming tools. A laboratory testing is developed to determine the evolution of the heat transfer coefficient in different glass/mould contact conditions (contact pressure, temperature, lubrication...). In this paper, trials are performed to determine heat transfer coefficient evolutions in experimental conditions close to the industrial blow-and-blow process conditions. In parallel of this work, a special interface element is implemented in a commercial Finite Element code in order to deal with heat transfer between glass and mould for non-meshing meshes and evolutive contact. This special interface element, implemented by using user subroutines, permits to introduce the previous heat transfer coefficient evolutions in the numerical modelings at the glass/mould interface in function of the local temperatures, contact pressures, contact time and kind of lubrication. The blow-and-blow forming simulation of a perfume bottle is finally performed to assess the special interface element performance. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

To improve the stability of superconducting magnets cooled by He II, it is considered that the utilization of the porous media enhances the heat transport capability of He II. In the present studies, the thermal hydraulic characteristics of He II through porous media have been investigated experimentally and numerically. Experimental results are presented about 6 porous media with various porosity, thickness and average pore diameters. Numerical results are reported about 4 porous media among them. In the present numerical analysis, the two-dimensional calculations have been performed for the turbulent Gorter-Mellink regime to understand the heat and mass transfer of the He II through the porous media in the case of the large heat input. The present numerical model was based on the two-fluid model with the Gorter-Mellink mutual friction and dealt with the classical friction loss and the tortuosity in the porous media. This paper discusses the influence of these additional terms on the heat and mass flow of He II through the porous media at the turbulent Gorter-Mellink regime. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]