Determination of Outside Heating Distribution Using an Inverse Algorithm for an Industry Hydrothermal Autoclave With Three-Dimensional Flows

2004 ◽  
Author(s):  
Hongmin Li ◽  
Minel J. Braun ◽  
G.-X. Wang ◽  
Edward A. Evans
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Fluid Flow ◽  
Heat Conduction ◽  
Flux Distribution ◽  
Cfd Simulation ◽  
Three Dimensional ◽  
Heat Flux Distribution ◽  
Inverse Algorithm ◽  
Small Magnitude

Hydrothermal growth is the industry method of preference to obtain high quality single crystals. Due to the high pressure and high temperature growth conditions, growth process is carried out in closed containers. During a growth run, the only flow and heat transfer that control crystal growers have is the outside heating. An inverse algorithm, used to obtain the heating distribution for an autoclave with a two-dimensional flow, is further developed and used to determine the heating distribution for an industry autoclave with three-dimensional flows. A cross-section area average temperature distribution is set as a target. With the three steps, including CFD simulation of the fluid flow, heat conduction in the metal wall, and heat conduction in the insulation layer, the heater heat flux distribution is determined. The distributions appear close to linear from the median height to the top/bottom with small magnitude deviation in the circumferential direction. Linearly distributed heaters, based on the determined heat flux distribution, are then used and heat transfer and fluid flow is numerically simulated with a conjugate model. The achieved temperature agrees well with the targeted one. The distribution and heating rates of linearly distributed heaters can be applied to industry autoclaves.

scholarly journals Thermal analysis in thin-film fluid regions of rectangular microgroove

2018 ◽  
Vol 22 (2) ◽  
pp. 899-897
Author(s):  
Xiaohong Gui ◽  
Xiange Song ◽  
Baisheng Nie
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Heat Flux ◽  
Contact Angle ◽  
Film Thickness ◽  
Flux Distribution ◽  
Total Heat ◽  
Heat Flux Distribution ◽  
Total Heat Transfer ◽  
Thin Film Thickness

The effects of contact angle and superheat on thin-film thickness and heat flux distribution occurring in a rectangle microgroove are numerically simulated. Accordingly, physical, and mathematical models are built in detail. Numerical results indicate that meniscus radius and thin-film thickness increase with the improvement of contact angle. The heat flux distribution in the thin-film region increases non-linearly as the contact angle decreases. The total heat transfer through the thin-film region increases with the improvement of superheat, and decreases as the contact angle increases. When the contact angle is equal to zero, the heat transfer in the thin-film region accounts for more than 80% of the total heat transfer. Intensive evaporation in the thin-film region plays a key role in heat transfer for the rectangle capillary microgroove. The liquid with higher wetting performance is more capable of playing the advantages of higher intensity heat transfer in thin- film region. The current investigation will result in a better understanding of thin- -film evaporation and its effect on the effective thermal conductivity in the rectangle microgroove.

scholarly journals Transient Heat Transfer in Rotating Cylinder - Thermography Measurement to Analyse Intense Heat Flux Distribution

2008 ◽  
Author(s):  
J.C. Batsale ◽  
J.P. Lasserre ◽  
M. Varenne-Pellegrini ◽  
V. Desormiere ◽  
L. Authesserre ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Flux Distribution ◽  
Rotating Cylinder ◽  
Transient Heat Transfer ◽  
Heat Flux Distribution ◽  
Intense Heat

EMC3-EIRENE simulations of neon impurity seeding effects on heat flux distribution on CFETR

2022 ◽  
Author(s):  
Shuyu Dai ◽  
Defeng Kong ◽  
Vincent Chan ◽  
Liang Wang ◽  
Yuhe Feng ◽  
...  
Keyword(s):  
Heat Flux ◽  
Heat Load ◽  
Flux Distribution ◽  
Three Dimensional ◽  
Input Power ◽  
Heat Flux Distribution ◽  
Maximum Heat ◽  
Maximum Heat Flux ◽  
Heat Loads ◽  
Injection Location

Abstract The numerical modelling of the heat flux distribution with neon impurity seeding on CFETR has been performed by the three-dimensional (3D) edge transport code EMC3-EIRENE. The maximum heat flux on divertor targets is about 18 MW m-2 without impurity seeding under the input power of 200 MW entering into the scrape-off layer. In order to mitigate the heat loads below 10 MW m-2, neon impurity seeded at different poloidal positions has been investigated to understand the properties of impurity concentration and heat load distributions for a single toroidal injection location. The majority of the studied neon injections gives rise to a toroidally asymmetric profile of heat load deposition on the in- or out-board divertor targets. The heat loads cannot be reduced below 10 MW m-2 along the whole torus for a single toroidal injection location. In order to achieve the heat load mitigation (<10 MW m-2) along the entire torus, modelling of sole and simultaneous multi-toroidal neon injections near the in- and out-board strike points has been stimulated, which indicates that the simultaneous multi-toroidal neon injections show a better heat flux mitigation on both in- and out-board divertor targets. The maximum heat flux can be reduced below 7 MWm-2 on divertor targets for the studied scenarios of the simultaneous multi-toroidal neon injections.

Co-Axial Laminar Multiphase Jet: A Novel Methodology for the Attainment Enhancement in Transition Boiling Regime

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Kashinath Barik ◽  
B. Swain ◽  
A.R. Pati ◽  
Susmit Chitransh ◽  
S.S. Mohapatra
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Flux Distribution ◽  
Flow Behavior ◽  
Heat Transfer Analysis ◽  
Heat Flux Distribution ◽  
Low Mass ◽  
Multiphase Fluid ◽  
Thermal Diffusivities ◽  
The Comparative Study

Abstract In the current investigation, by using a very low mass flux co-axial laminar multiphase fluid jet, enhancement in heat transfer rate, uniformity in heat flux distribution, and reduction in coolant consumption rate characteristics are simultaneously tried to achieve in case of cooling from a very high initial temperature (900 °C). The information on quenching technology depicting all the above-mentioned advantages has not been reported in the literature. In the present work, kerosene–water, nanofluid (Al2O3 = 0.15%)–kerosene, and nanofluid (Al2O3 = 0.15%)–polyethylene glycol combinations were used for co-axial cooling experimentation. From the heat transfer analysis, it is observed that nanofluid (Al2O3 = 0.15%) and kerosene combination produces maximum critical heat flux due to the alteration of thermophysical and interfacial properties, which enhance the driving force and flow behavior defining momentum and thermal diffusivities in the favorable direction of heat transfer, respectively. In addition to the above, the comparative study ensures a significant reduction in coolant consumption and augmentation in uniformity in heat flux distribution.

Determination of Convective Heat Flux on Steady-State Heat Transfer Surfaces With Arbitrarily Specified Boundaries

1996 ◽  
Vol 118 (4) ◽  
pp. 850-856 ◽  
Author(s):  
B. G. Wiedner ◽  
C. Camci
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Steady State ◽  
Film Cooling ◽  
Flux Distribution ◽  
Heat Flux Distribution ◽  
Steady State Heat ◽  
Steady State Heat Transfer ◽  
Film Cooling Holes

The present study focuses on the high-resolution determination of local heat flux distributions encountered in forced convection heat transfer studies. The specific method results in an uncertainty level less than 4 percent of the heat transfer coefficient on surfaces with arbitrarily defined geometric boundaries. Heat transfer surfaces constructed for use in steady-state techniques typically use rectangular thin foil electric heaters to generate a constant heat flux boundary condition. There are also past studies dealing with geometrically complex heating elements. Past studies have either omitted the nonuniform heat flux regions or applied correctional techniques that are approximate. The current study combines electric field theory and a finite element method to solve directly for a nonuniform surface heat flux distribution due to the specific shape of the heater boundary. Heat generation per unit volume of the surface heater element in the form of local Joule heating is accurately calculated using a finite element technique. The technique is shown to be applicable to many complex convective heat transfer configurations. These configurations often have complex geometric boundaries such as turbine endwall platforms, surfaces disturbed by film cooling holes, blade tip sections, etc. A complete high-resolution steady-state heat transfer technique using liquid crystal thermography is presented for the endwall surface of a 90 deg turning duct. The inlet flow is fully turbulent with an inlet Re number of 360,000. The solution of the surface heat flux distribution is also demonstrated for a heat transfer surface that contains an array of discrete film cooling holes. The current method can easily be extended to any heat transfer surface that has arbitrarily prescribed boundaries.

scholarly journals Transport in Flat Heat Pipes at High Heat Fluxes From Multiple Discrete Sources

2004 ◽  
Vol 126 (3) ◽  
pp. 347-354 ◽  
Author(s):  
Unnikrishnan Vadakkan ◽  
Suresh V. Garimella ◽  
Jayathi Y. Murthy
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Fluid Flow ◽  
Heat Pipe ◽  
Three Dimensional ◽  
Heat Pipes ◽  
Density Change ◽  
Heat Sources ◽  
Discrete Heat Sources ◽  
Energy Equations

A three-dimensional model has been developed to analyze the transient and steady-state performance of flat heat pipes subjected to heating with multiple discrete heat sources. Three-dimensional flow and energy equations are solved in the vapor and liquid regions, along with conduction in the wall. Saturated flow models are used for heat transfer and fluid flow through the wick. In the wick region, the analysis uses an equilibrium model for heat transfer and a Brinkman-Forchheimer extended Darcy model for fluid flow. Averaged properties weighted with the porosity are used for the wick analysis. The state equation is used in the vapor core to relate density change to the operating pressure. The density change due to pressurization of the vapor core is accounted for in the continuity equation. Vapor flow, temperature and hydrodynamic pressure fields are computed at each time step from coupled continuity/momentum and energy equations in the wick and vapor regions. The mass flow rate at the interface is obtained from the application of kinetic theory. Predictions are made for the magnitude of heat flux at which dryout would occur in a flat heat pipe. The input heat flux and the spacing between the discrete heat sources are studied as parameters. The location in the heat pipe at which dryout is initiated is found to be different from that of the maximum temperature. The location where the maximum capillary pressure head is realized also changes during the transient. Axial conduction through the wall and wick are seen to play a significant role in determining the axial temperature variation.

Ray-Thermal Sequential Coupled Heat Transfer ANALYSIS of Porous Media Receiver for Solar Dish Collector

2013 ◽  
Vol 442 ◽  
pp. 169-175 ◽  
Author(s):  
Fu Qiang Wang
Keyword(s):  
Heat Transfer ◽  
Boundary Condition ◽  
Heat Flux ◽  
Porous Media ◽  
Flux Distribution ◽  
Heat Transfer Analysis ◽  
Uniform Heat Flux ◽  
Heat Flux Distribution ◽  
Uniform Heat ◽  
Distribution Boundary

For the sake of reflecting the concentrated heat flux distribution boundary condition as genuine as possible during simulation, the sequential coupled optical-thermal heat transfer analysis is introduced for porous media receiver. During the sequential coupled numerical analysis, the non-uniform heat flux distribution on the fluid entrance surface of porous media receiver is obtained by Monte-Carlo ray tracing method. Finite element method (FEM) is adopted to solve energy equation using the calculated heat flux distribution as the third boundary condition. The dimensionless temperature distribution comparisons between uniform and non-uniform heat flux distribution boundary conditions, various porosities, and different solar dish concentrator tracking errors are investigated in this research.

2D divertor heat flux distribution using a 3D heat conduction solver in National Spherical Torus Experiment

2013 ◽  
Vol 84 (2) ◽  
pp. 023505 ◽  
Author(s):  
K. F. Gan ◽  
J-W. Ahn ◽  
J.-W. Park ◽  
R. Maingi ◽  
A. G. McLean ◽  
...  
Keyword(s):  
Heat Flux ◽  
Heat Conduction ◽  
Flux Distribution ◽  
Heat Flux Distribution ◽  
Spherical Torus

scholarly journals Gravity darkening in late-type stars

2018 ◽  
Vol 609 ◽  
pp. A124 ◽  
Author(s):  
R. Raynaud ◽  
M. Rieutord ◽  
L. Petitdemange ◽  
T. Gastine ◽  
B. Putigny
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Nusselt Number ◽  
Coriolis Force ◽  
Flux Distribution ◽  
Parameter Study ◽  
Rossby Number ◽  
Heat Flux Distribution ◽  
Convective Envelope ◽  
Background Density

Context. Recent interferometric data have been used to constrain the brightness distribution at the surface of nearby stars, in particular the so-called gravity darkening that makes fast rotating stars brighter at their poles than at their equator. However, good models of gravity darkening are missing for stars that posses a convective envelope. Aim. In order to better understand how rotation affects the heat transfer in stellar convective envelopes, we focus on the heat flux distribution in latitude at the outer surface of numerical models. Methods. We carry out a systematic parameter study of three-dimensional, direct numerical simulations of anelastic convection in rotating spherical shells. As a first step, we neglect the centrifugal acceleration and retain only the Coriolis force. The fluid instability is driven by a fixed entropy drop between the inner and outer boundaries where stress-free boundary conditions are applied for the velocity field. Restricting our investigations to hydrodynamical models with a thermal Prandtl number fixed to unity, we consider both thick and thin (solar-like) shells, and vary the stratification over three orders of magnitude. We measure the heat transfer efficiency in terms of the Nusselt number, defined as the output luminosity normalised by the conductive state luminosity. Results. We report diverse Nusselt number profiles in latitude, ranging from brighter (usually at the onset of convection) to darker equator and uniform profiles. We find that the variations of the surface brightness are mainly controlled by the surface value of the local Rossby number: when the Coriolis force dominates the dynamics, the heat flux is weakened in the equatorial region by the zonal wind and enhanced at the poles by convective motions inside the tangent cylinder. In the presence of a strong background density stratification however, as expected in real stars, the increase of the local Rossby number in the outer layers leads to uniformisation of the surface heat flux distribution.

Optimal Sizing of Planar Thermal Spreaders

1994 ◽  
Vol 116 (2) ◽  
pp. 296-301 ◽  
Author(s):  
S. Hingorani ◽  
C. J. Fahrner ◽  
D. W. Mackowski ◽  
J. S. Gooding ◽  
R. C. Jaeger
Keyword(s):  
Heat Transfer ◽  
Flux Distribution ◽  
Environmental Temperature ◽  
Three Dimensional ◽  
Uniform Heat Flux ◽  
Two Dimensional ◽  
Heat Flux Distribution ◽  
Optimal Thickness ◽  
Dimensionless Variables ◽  
Biot Numbers

Two-dimensional cylindrical and three-dimensional Cartesian thermal spreaders are studied. One of the surfaces is convectively coupled to a uniform environmental temperature while the opposite surface is subjected to a uniform heat flux distribution over a portion of its boundary. The problem is generalized through the introduction of appropriate dimensionless variables, and analytical solutions for the temperature field are presented for each coordinate system. The solutions depend on the usual geometric and heat transfer groups. It is found that, for a range of realistic Biot numbers and a given ratio of the spreader to heater dimensions, a dimensionless spreader thickness exists for which the temperature of the heater reaches a minimum value. Optimal thickness curves are presented for these ranges.

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