An experimental procedure for estimating the radiation heat transfer coefficient in combined convective and radiative heat transfer

1987 ◽  
Vol 20 (3) ◽  
pp. 308-310 ◽  
Author(s):  
J G Symons
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Radiation Heat Transfer ◽  
Radiation Heat ◽  
Experimental Procedure

Meshless Local Petrov-Galerkin Method for Heat Transfer Analysis

2013 ◽  
Author(s):  
Singiresu S. Rao
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Boundary Conditions ◽  
Transfer Coefficient ◽  
Transfer Problem ◽  
Radiation Heat Transfer ◽  
Heat Transfer Problem ◽  
Radiation Heat ◽  
Mlpg Method ◽  
Transfer Problems

A meshless local Petrov-Galerkin (MLPG) method is proposed to obtain the numerical solution of nonlinear heat transfer problems. The moving least squares scheme is generalized, to construct the field variable and its derivative continuously over the entire domain. The essential boundary conditions are enforced by the direct scheme. The radiation heat transfer coefficient is defined, and the nonlinear boundary value problem is solved as a sequence of linear problems each time updating the radiation heat transfer coefficient. The matrix formulation is used to drive the equations for a 3 dimensional nonlinear coupled radiation heat transfer problem. By using the MPLG method, along with the linearization of the nonlinear radiation problem, a new numerical approach is proposed to find the solution of the coupled heat transfer problem. A numerical study of the dimensionless size parameters for the quadrature and support domains is conducted to find the most appropriate values to ensure convergence of the nodal temperatures to the correct values quickly. Numerical examples are presented to illustrate the applicability and effectiveness of the proposed methodology for the solution of heat transfer problems involving radiation with different types of boundary conditions. In each case, the results obtained using the MLPG method are compared with those given by the FEM method for validation of the results.

Average Wall Radiative Heat Transfer Characteristic of Isothermal Radiative Medium in Inner Straight Fin Tubes

2021 ◽  
Author(s):  
Wenping Peng ◽  
Min Xu ◽  
Xiaoxia Ma ◽  
Xiulan Huai
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Radiative Heat Transfer ◽  
Calculation Method ◽  
Radiative Heat ◽  
Solid Surfaces ◽  
Design Calculation ◽  
Radiative Heat Transfer Coefficient ◽  
Fin Tubes

Abstract Wall radiative heat transfer in inner straight fin tubes is very complex considering the coupling of heat conduction in fins and radiative heat transfer of medium with solid surfaces, influenced by a number of factors such as fin parameters, radiative pro perties and run conditions. In this study, a simplified method is used.The average radiative heat transfer between radiative medium and solid surfaces is firstly studied by simulation with fins assumed having a constant temperature. Then an approximate correlation of this radiative heat transfer coefficient is proposed using the traditional radiative heat transfer calculation method with a view coefficient, having a error within 15%. A calculation method of average wall radiative heat transfer coefficient is further proposed by fin theory with an average temperature of fin surface used to consider the varying of the temperature along the fin when the conductivity of fins is finite. Using the predicting method proposed, a method for design calculation of fins in tubes to optimize wall radiative heat transfer is also given with three dimensionless numbers of p/n, 2H/D and nt/pD defined. Three cases of are analyzed in detail based on the design calculation method. It is verified that the radiative heat transfer could be enhanced twice by introducing fins. Under the same h0, conductivity and emissivity are two important factors to choose the material for fins.The micro-fins or the special treatments on the tube wall are a best choice for the fin material having a relatively small conductivity.

Anomalous Heat Diffusion in a Chain of Large Particles Through Radiative Heat Transfer

2019 ◽  
Author(s):  
B. K. Liu ◽  
J. M. Zhao ◽  
L. H. Liu
Keyword(s):  
Heat Transfer ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Radiation Heat Transfer ◽  
Heat Diffusion ◽  
Far Field ◽  
Radiation Heat ◽  
Diffusive Regime ◽  
Particulate System ◽  
Anomalous Heat

Abstract Radiative heat transfer in particulate system has many applications in industry. Recently, the anomalous heat diffusion was reported for particulate system in near field thermal radiation heat transfer, and the existence of heat super-diffusive regimes was observed and the spread of heat can be described by Levy flight. In this work, attention is paid to investigate whether there is anomalous heat diffusion in far-field radiative heat transfer or not. Specifically, this study is focused on the radiative heat transport of a system, consisting of optically large particles, in the geometric optic range. Those particles are arranged in a linear chain surrounded by reflective walls and all particles are identical and equally spaced. The effect of the boundary type and particle surface emissivity on the heat diffusion is also investigated. The heat diffusion behavior in the far-field is studied based on Monte Carlo ray tracing method and the fractional diffusion equation in one dimension. The result indicates the existence of anomalous heat diffusion in the far-field by analyzing the asymptotic behavior of radiation distribution function (RDF). It’s shown that the distribution of RDF decays in power law and can be divided into two parts: for near the source particle, heat diffusive regime is super-diffusive (according to the analysis of fractional diffusion equation), while for far from the source particle, heat diffusive regime becomes sub-diffusive. Moreover, the kind of boundary type and particle wall emissivity have a significant influence on the heat diffusion of the far-field radiation heat transfer. This work will help the understanding of radiation heat transfer in particulate system in the far-field.

Analysis of Radiation Heat Transfer in an Enclosure Fire Including the Effect of Scattering

2005 ◽  
Author(s):  
W. W. Yuen ◽  
W. K. Chow
Keyword(s):  
Heat Transfer ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Radiation Heat Transfer ◽  
Zone Model ◽  
Fire Growth ◽  
Radiation Heat ◽  
Fire Zone ◽  
Enclosure Fire ◽  
Radiative Exchange

The need for an accurate simulation of the radiative heat transfer in a fire zone model is demonstrated. Results show that the lack of an accurate model of the relevant physics of radiative heat transfer can lead to uncertainty which can severely limit the usefulness of a fire zone model. An accurate numerical model of radiative exchange including the effect of scattering, is applied to simulate the effect of radiative heat transfer on fire growth. Typical conservation equations in a fire zone models are used.

Meshless Local Petrov-Galerkin Method for Three-Dimensional Heat Transfer Analysis

2012 ◽  
Vol 134 (11) ◽  
Author(s):  
Jun Tian ◽  
Singiresu S. Rao
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Boundary Conditions ◽  
Transfer Coefficient ◽  
Transfer Problem ◽  
Radiation Heat Transfer ◽  
Three Dimensional ◽  
Radiation Heat ◽  
Mlpg Method ◽  
Transfer Problems

A meshless local Petrov-Galerkin (MLPG) method is proposed to obtain the numerical solution of nonlinear heat transfer problems. The moving least squares scheme is generalized to construct the field variable and its derivatives continuously over the entire domain. The essential boundary conditions are enforced by the direct scheme. By defining a radiation heat transfer coefficient, the nonlinear boundary value problem is solved as a sequence of linear problems each time updating the radiation heat transfer coefficient. The matrix formulation is used to drive the equations for a three dimensional nonlinear coupled radiation heat transfer problem. By using the MPLG method, along with the linearization of the nonlinear radiation problem, a new numerical approach is proposed to find the solution of the coupled heat transfer problem. A numerical study of the dimensionless size parameters for the quadrature and support domains is conducted to find the most appropriate values to ensure convergence of the nodal temperatures to the correct values quickly. Numerical examples are presented to illustrate the applicability and effectiveness of the proposed methodology for the solution of one-, two-, and three-dimensional heat transfer problems involving radiation with different types of boundary conditions. In each case, the results obtained using the MLPG method are compared with those given by the finite element method (FEM) method for validating the results.

scholarly journals Determination of Radiative Heat Transfer Coefficient at High Temperatures Using a Combined Experimental-Computational Technique

2015 ◽  
Vol 15 (2) ◽  
pp. 85-91 ◽  
Author(s):  
Václav Kočí ◽  
Jan Kočí ◽  
Tomáš Korecký ◽  
Jiří Maděra ◽  
Robert Č Černý
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Transfer Coefficient ◽  
Computational Modeling ◽  
Transfer Coefficient ◽  
High Temperatures ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Calculated Data ◽  
Radiative Heat Transfer Coefficient

Abstract The radiative heat transfer coefficient at high temperatures is determined using a combination of experimental measurement and computational modeling. In the experimental part, cement mortar specimen is heated in a laboratory furnace to 600°C and the temperature field inside is recorded using built-in K-type thermocouples connected to a data logger. The measured temperatures are then used as input parameters in the three dimensional computational modeling whose objective is to find the best correlation between the measured and calculated data via four free parameters, namely the thermal conductivity of the specimen, effective thermal conductivity of thermal insulation, and heat transfer coefficients at normal and high temperatures. The optimization procedure which is performed using the genetic algorithms provides the value of the high-temperature radiative heat transfer coefficient of 3.64 W/(m2K).

Experimental study of radiation heat transfer coefficient of diffusion flames

2007 ◽  
Vol 29 (2) ◽  
pp. 98-104
Author(s):  
Bui Van Ga ◽  
Le Van Tuy ◽  
Huynh Ba Vang ◽  
Le Van Lu ◽  
Nguyen Ngoc Linh
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Heat Transfer Coefficient ◽  
Diesel Engine ◽  
Transfer Coefficient ◽  
Combustion Chamber ◽  
Diffusion Flames ◽  
Radiation Heat Transfer ◽  
Radiation Heat ◽  
Coefficient Of Diffusion

Basing on analysis of flame pictures given by visioscope by two-color method, the paper presents evolution of radiation heat transfer coefficient \(\varepsilon_s\) of soot in diffusion flames in air, in furnace and in combustion chamber of Diesel engine. \(\varepsilon_s\) reaches respectively its maximal value of 0.15; 0.30 and 0.45 in regions of maximal soot fraction of the three above flames.

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