ANALYSIS OF THE TRANSIENT THERMAL RESPONSE OF A SOLID VIA A CONJUGATE HEAT TRANSFER METHOD

2008 ◽  
Author(s):  
Marc-Paul Errera ◽  
Gilles Chaineray
Keyword(s):  
Heat Transfer ◽  
Conjugate Heat Transfer ◽  
Thermal Response ◽  
Transfer Method ◽  
Transient Thermal ◽  
Transient Thermal Response

A Study of Transient Heat Transfer in Long Insulated Wires

1976 ◽  
Vol 98 (1) ◽  
pp. 127-132 ◽  
Author(s):  
Y. Jaluria
Keyword(s):  
Heat Transfer ◽  
Boundary Conditions ◽  
Outer Cylinder ◽  
Thermal Response ◽  
Transient Behavior ◽  
The Body ◽  
Surface Boundary ◽  
Surface Boundary Conditions ◽  
Transient Thermal ◽  
Transient Thermal Response

This study concerns the transient thermal response of long insulated wires, a composite cylinder configuration, in which a highly conducting inner cylinder is sheathed in an outer cylinder of an insulating material. The study examines the heat transfer in such a cylindrical configuration and determines the parameters that govern its thermal response. A study of the transient behavior under various important surface boundary conditions, particularly the constant surface heat flux circumstance, is undertaken. The dependence of the transient response of the body, in terms of the characteristic surface and conductor temperatures, of the temperature distribution across the insulation and of other important physical aspects on the boundary conditions and on the governing parameters is investigated. The governing equation and boundary conditions are generalized and the solution obtained numerically to obtain the desired flexibility required for the variation in the boundary conditions. Several important and interesting results are obtained which indicate the nature of the thermal response and also the criteria for obtaining a desired variation in the transient behavior of this frequently encountered configuration.

scholarly journals Simulation of Discrete Blood Vessel Effects on the Thermal Signature of a Melanoma Lesion

2013 ◽  
Author(s):  
Sri Kamal Kandala ◽  
Daxiang Deng ◽  
Cila Herman
Keyword(s):  
Heat Transfer ◽  
Blood Vessel ◽  
Evaluation Criteria ◽  
Thermal Response ◽  
Skin Surface ◽  
Cancerous Lesion ◽  
Surrounding Healthy Tissue ◽  
Thermal Signature ◽  
Transient Thermal ◽  
Transient Thermal Response

The effect of the underlying blood vessel on the transient thermal response of the skin surface with and without a melanoma lesion is studied. A 3D computational model of the layers of the skin tissue with cancerous lesion was developed in COMSOL software package. Heat transfer in the skin layers and the lesion is governed by the Pennes bio-heat equation, while the blood vessel is modeled as fully developed pipe flow with constant heat transfer coefficient. The effect of various pertinent parameters, such as diameter of the blood vessel, lateral location of the blood vessel relative to the lesion, flow velocity of the blood, on the skin surface temperature distribution, have been studied in the paper. The results show significant influence of the underlying blood vessel on the temperature of the skin surface and lesion as well as on the surrounding healthy tissue. Thus, a need for development of evaluation criteria for detection of malignant lesions in the presence of blood vessels is is discussed.

A Parametric Study of the Transient Ablation of Teflon

1972 ◽  
Vol 94 (4) ◽  
pp. 347-354 ◽  
Author(s):  
Barry L. Clark
Keyword(s):  
Heat Transfer ◽  
Nonlinear Estimation ◽  
Thermal Response ◽  
One Dimensional ◽  
Transfer Parameters ◽  
Transient Thermal ◽  
Transient Thermal Response ◽  
Available Information ◽  
Parameter Values ◽  
Ablation Model

An analytical and experimental investigation was performed to simultaneously determine 18 ablation heat-transfer parameters for Teflon by the method of nonlinear estimation. A transient one-dimensional ablation model solved numerically was utilized to represent the thermal response of Teflon samples that were instrumented in-depth with thermocouples. The nonlinear estimation computer program was based on a modified version of Marquardt’s algorithm. A matching of the predicted and measured temperatures was effected and the results for the parameter values were in accord with available information in the literature. It was concluded that the ablation model accurately predicted the transient thermal response and surface recession of ablating Teflon.

Comparison of a Conventional Thermal Analysis of a Turbine Cascade to a Full Conjugate Heat Transfer Computation

2008 ◽  
Author(s):  
Christoph Starke ◽  
Erik Janke ◽  
Toma´sˇ Hofer ◽  
Davide Lengani
Keyword(s):  
Heat Transfer ◽  
Boundary Condition ◽  
Conjugate Heat Transfer ◽  
Complex Geometry ◽  
Thermal Analyses ◽  
Turbine Cascade ◽  
Transfer Coefficients ◽  
Commercial Code ◽  
Blade Tip ◽  
Transfer Method

Recent development in commercial CFD codes offers possibilities to include the solid body in order to perform conjugate heat transfer computations for complex geometries. The current paper aims to analyse the differences between a conjugate heat transfer computation and conventional uncoupled approaches where a heat transfer coefficient is first derived from a flow solution and then taken as boundary condition for a thermal conduction analysis of the solid part. Whereas the thermal analyses are done with a Rolls-Royce in-house finite element code, the CFD as well as the conjugate heat transfer computation are done using the new version 8 of the commercial code Fine Turbo from Numeca International. The analysed geometry is a turbine cascade that was tested by VKI in Brussels within the European FP6 project AITEB 2. First, the paper presents the aerodynamic results. The pure flow solutions are validated against pressure measurements of the cascade test. Then, the heat transfer from flow computations with wall temperature boundary conditions is compared to the measured heat transfer. Once validated, the heat transfer coefficients are used as boundary condition for three uncoupled thermal analyses of the blade to predict its surface temperatures in a steady state. The results are then compared to a conjugate heat transfer method. Therefore, a mesh of the solid blade was added to the validated flow computation. The paper will present and compare the results of conventional uncoupled thermal analyses with different strategies for the wall boundary condition to results of a conjugate heat transfer computation. As it turns out, the global results are similar but especially the over-tip region with its complex geometry and flow structure and where effective cooling is crucial shows remarkable differences because the conjugate heat transfer solution predicts lower blade tip temperatures. This will be explained by the missing coupling between the fluid and the solid domain.

Influence of Phonon Dispersion on Transient Thermal Response of Silicon-on-Insulator Transistors Under Self-Heating Conditions

2006 ◽  
Vol 129 (7) ◽  
pp. 790-797 ◽  
Author(s):  
Rodrigo A. Escobar ◽  
Cristina H. Amon
Keyword(s):  
Computational Models ◽  
Phonon Dispersion ◽  
Thermal Response ◽  
Domain Size ◽  
Phonon Transport ◽  
Silicon On Insulator ◽  
Nonlinear Relation ◽  
Temperature Levels ◽  
Transient Thermal ◽  
Transient Thermal Response

Lattice Boltzmann method (LBM) simulations of phonon transport are performed in one-dimensional (1D) and 2D computational models of a silicon-on-insulator transistor, in order to investigate its transient thermal response under Joule heating conditions, which cause a nonequilibrium region of high temperature known as a hotspot. Predictions from Fourier diffusion are compared to those from a gray LBM based on the Debye assumption, and from a dispersion LBM which incorporates nonlinear dispersion for all phonon branches, including explicit treatment of optical phonons without simplifying assumptions. The simulations cover the effects of hotspot size and heat pulse duration, considering a frequency-dependent heat source term. Results indicate that, for both models, a transition from a Fourier diffusion regime to a ballistic phonon transport regime occurs as the hotspot size is decreased to tens of nanometers. The transition is characterized by the appearance of boundary effects, as well as by the propagation of thermal energy in the form of multiple, superimposed phonon waves. Additionally, hotspot peak temperature levels predicted by the dispersion LBM are found to be higher than those from Fourier diffusion predictions, displaying a nonlinear relation to hotspot size, for a given, fixed, domain size.

Conjugate Heat Transfer Simulation of the Intercooled Compressor Vanes Based on Discontinuous Galerkin Method

2016 ◽  
Author(s):  
Long-gang Liu ◽  
Chun-wei Gu ◽  
Xiao-dong Ren
Keyword(s):  
Heat Transfer ◽  
Discontinuous Galerkin ◽  
Gas Turbines ◽  
Conjugate Heat Transfer ◽  
Main Stream ◽  
Two Dimensional ◽  
Convective Cooling ◽  
Cooling Channels ◽  
Transfer Method ◽  
Aero Engines

Convective cooling channels are applied in a two-dimensional compressor vane to use the intercooling method to improve the efficiency of Brayton cycle and reduce the temperature of the vane. In this paper, we analyze the effect of coolant to the aerodynamic performance and heat transfer performance of the main stream and the vane. For the case of a two-dimensional compressor vane NACA65-(12A2I8b)10, the vane which has five convective cooling channels has been numerically simulated in different test conditions by discontinuous Galerkin (DG) method. The coolant is supercritical carbon dioxide whose pressure is 10MPa. Conjugate heat transfer method has been used in this paper. The numerical simulation result is similar to the experiment data and has been compared with the result of the vane without cooling channels to prove the effect of cooling channels. Cooling channels have large effect on the distribution of temperature and heat transfer coefficient. In addition, the relationship between Nu and Re on the fluid-solid interface has been analyzed and a suitable empirical equation has been obtained. This work analyzes the effect of intercooling system in the compressor and give several advice on future engineering applications in aero engines and gas turbines.

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