Markov Analysis of Radiative Transfer in Specular Enclosures

1991 ◽  
Vol 113 (2) ◽  
pp. 429-436 ◽  
Author(s):  
R. L. Billings ◽  
J. W. Barnes ◽  
J. R. Howell ◽  
O. E. Slotboom
Keyword(s):  
Heat Transfer ◽  
Radiative Transfer ◽  
Markov Chains ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Previous Literature ◽  
Markov Analysis ◽  
Two Parameter

This paper is directed at the use of Markov chains in the modeling of radiative heat transfer in specular enclosures containing nonparticipating gases. Following a brief review of previous literature in that area of investigation, a two-parameter state definition is given. The analysis of general infinitely long enclosures using that definition is then discussed, and the paper concludes with a report of selected implementation results.

Accelerate Iteration of Least-Squares Finite Element Method for Radiative Heat Transfer in Participating Media With Diffusely Reflecting Walls

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
Wei An ◽  
Tong Zhu ◽  
NaiPing Gao
Keyword(s):  
Heat Transfer ◽  
Finite Element Method ◽  
Boundary Condition ◽  
Finite Element ◽  
Radiative Transfer ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Present Model ◽  
Participating Media ◽  
Element Method

A high reflectivity of walls often leads to prohibitive computation time in the numerical simulation of radiative heat transfer. Such problem becomes very serious in many practical applications, for example, metal processing in high-temperature environment. The present work proposes a modified diffusion synthetic acceleration model to improve the convergence of radiative transfer calculation in participating media with diffusely reflecting boundary. This model adopts the P1 diffusion approximation to rectify the scattering source term of radiative transfer equation and the reflection term of the boundary condition. The corrected formulation for boundary condition is deduced and the algorithm is realized by finite element method. The accuracy of present model is verified by comparing the results with those of Monte Carlo method and finite element method without any accelerative technique. The effects of emissivity of walls and optical thickness on the convergence are investigated. The results indicate that the accuracy of present model is reliable and its accelerative effect is more obvious for the optically thick and scattering dominated media with intensive diffusely reflecting walls.

Modeling and analysis of 3D radiative heat transfer in combustor

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Yue Zhou ◽  
Xijuan Zhu ◽  
Qisheng Guo ◽  
Pengcheng Qi ◽  
Jing Ma
Keyword(s):  
Heat Transfer ◽  
Radiative Transfer ◽  
Thermal Radiation ◽  
Numerical Method ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Radiant Energy ◽  
Radiative Properties ◽  
Direct Technique

Abstract Compared with wall emission, gas thermal radiation is much more complicated because of its nongray and volumetric property. In this paper, a numerical method is established to calculate 3D radiative heat transfer in combustor by modelling radiative transfer as well as nongray radiative properties of combustion gases. Energy exchanges caused by thermal radiation and conduction are calculated and compared in a rectangular combustor, which shows the significant role of thermal radiation in heating fuel-air mixtures and prompting internal combustion reactions. Besides, radiative heat flux on the wall is also quite obvious although a non-contacting flow case, revealing the special challenges for thermal protections brought by radiant energy. Lastly, increasing the working pressure means much more participating species in radiative transfer process and the radiative effects will be also magnified. The numerical method in this paper provides a direct technique to analyze the role of thermal radiation in complex thermochemical reactions while the application case proves the necessity of coupling a high-accuracy radiation model when simulating combustion and flame propagation.

An Efficient Method for Radiative Heat Transfer Applied to a Turbulent Channel Flow

2009 ◽  
Vol 132 (2) ◽  
Author(s):  
Atsushi Sakurai ◽  
Shigenao Maruyama ◽  
Koji Matsubara ◽  
Takahiro Miura ◽  
Masud Behnia
Keyword(s):  
Heat Transfer ◽  
Radiative Transfer ◽  
Channel Flow ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Simple Algorithm ◽  
Turbulent Channel Flow ◽  
Simulation Method ◽  
Heat Fluxes ◽  
Independent Column

The purpose of this paper is to consider a possibility of the independent column approximation for solving the radiative heat fluxes in a 3D turbulent channel flow. This simulation method is the simplest extension of the plane-parallel radiative heat transfer. The test case of the temperature profile was obtained from the direct numerical simulation. We demonstrate the comparison between the 3D radiative transfer simulation and the independent column approximation with an inhomogeneous temperature field and optical properties. The above mentioned results show the trivial discrepancies between the 3D simulation and the independent column approximation. The required processing time for the independent column approximation is much faster than the 3D radiative transfer simulation due to the simple algorithm. Although the independent column simulation is restricted to simple configurations such as channel flow in this paper, wide application areas are expected due to the computational efficiency.

scholarly journals P1-approximation for radiative transfer: application to SF6 + Cu arc plasmas

2014 ◽  
Vol 13 (1) ◽  
Author(s):  
Nadezhda Bogatyreva ◽  
Milada Bartlova ◽  
Vladimir Aubrecht ◽  
Vladimir Holcman
Keyword(s):  
Heat Transfer ◽  
Radiative Transfer ◽  
Theoretical Prediction ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Arc Plasmas

AbstractThe objective of the paper consists of a theoretical prediction of radiative heat transfer in arc plasmas of SF

Analytical Solution Under Two-Flux Approximation to Radiative Heat Transfer in Absorbing Emitting and Anisotropically Scattering Medium

2010 ◽  
Vol 132 (12) ◽  
Author(s):  
Xin-Lin Xia ◽  
Dong-Hui Li ◽  
Feng-Xian Sun
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Radiative Transfer ◽  
Analytical Solution ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Thermal Protection ◽  
Isotropic Scattering ◽  
Scattering Media ◽  
Flux Approximation

Radiative transfer in absorbing, emitting, and highly anisotropically scattering media is widely encountered in high temperature applications such as pulverized coal firing furnaces and high temperature thermal protection materials. Efficient and effective solution methods for the transfer process are very crucial, especially in thermal radiation related reverse problems and optimization designs. In this study, the analytical solution for radiative heat transfer in an absorbing, emitting, and anisotropically scattering slab between two parallel gray walls are derived under the two-flux approximation. Explicit expression for the radiative heat flux in a slab is obtained under two-flux approximation. The reliability and adaptability of an analytical solution is examined in case studies by comparing with the Monte Carlo results. Comparative studies indicate that the analytical solution can be used in radiative transfer calculation in an absorbing emitting and anisotropically scattering slab. It is much more applicable in a forward and isotropic scattering slab than in an absorbing one, especially in a forward scattering slab. Because of simplicity and high computing efficiency with the analytical solution, it may be useful in reverse radiative transfer problems, in optimization design, and in developing some numerical schemes on radiative heat transfer.

Sphere-to-Sphere Radiative Transfer Coefficient for Packed Sphere System

2001 ◽  
Author(s):  
S. H.-K. Lee ◽  
S. C.-H. Ip ◽  
A. K. C. Wu
Keyword(s):  
Heat Transfer ◽  
Radiative Transfer ◽  
Transfer Coefficient ◽  
Radiative Heat Transfer ◽  
Transfer Equation ◽  
Radiative Heat ◽  
Radiative Transfer Equation ◽  
Radiative Properties ◽  
Equation Approach ◽  
Packed Sphere

Abstract Rapid sintering is one of the most attractive metalworking technologies due to its ability to fabricate the final product with different microstructure in an economical manner. During this process, the high heating rate would induce a great thermal gradient to the sintering part. Such temperature differences affect the microstructure of the product, which in turn leads to the occurrence of microstructure defects. However, for this non-isothermal sintering, the present Radiative Transfer Equation approach or Units/Cells approach cannot effectively compute the temperature distributions inside the porous media, so as to predict the part defects. Cumbersome computations are needed for the Radiative Transfer Equation approach. For the Units/Cells approach, the use of regular assembly in the model limits the analysis of complex packed sphere systems. This study seeks to simplify the entire computational process for different packed sphere systems. By introducing a Radiative Transfer Coefficient (RTC) approach, the computation of radiative heat transfer within the porous bed can be enhanced. The newly introduced Radiative Transfer Coefficient is defined as the ratio of radiative energy exchange, including direct and indirect exchange, from the emitting sphere to the receiving sphere, which is a function of the system microstructure and radiative properties. A set of energy-balanced algebraic equations can then be established. With an appropriate initial energy guess for each sphere, these equations can be solved by the Gauss-Seidel iteration scheme, thereby computing the radiative heat transfer in packed sphere systems with different microstructures and radiative properties. The temperature for each sphere can therefore be computed right away. This model has been validated in different perspectives. With this RTC approach, the overall computational time required is significantly shorter, providing a set of fine-resolution temperature solution.

scholarly journals Validation of Numerical Methods at a Confined Turbulent Natural Gas Diffusion Flame Considering Detailed Radiative Transfer

1998 ◽  
Author(s):  
Benedikt Ganz ◽  
Peter Schmittel ◽  
Rainer Koch ◽  
Sigmar Wittig
Keyword(s):  
Heat Transfer ◽  
Radiative Transfer ◽  
Flow Field ◽  
Radiative Heat Transfer ◽  
Diffusion Flame ◽  
Radiative Heat ◽  
Gas Diffusion ◽  
Reacting Flow ◽  
Spectral Radiation ◽  
Mechanical Methods

Radiation heat transfer in flames depends strongly on local quantities such as pressure, temperature and concentration of participating species. In the present study, 3D numerical calculations of radiative heat transfer together with the reacting flow field are compared to detailed measurements of the velocity, temperature and spectral radiation field of a model combustor. The geometry of the combustion chamber (dch = 0.5m), the flame configuration (type-II swirling, diffusion flame) and the highly turbulent flow conditions resemble the characteristics of industrial combustors. The concentrations of CO2, H2O, CO, CH4, NO, NOx, O2 and H2 as well as local mean temperatures and their fluctuations were recorded at 300 locations at 14 axial planes. The radiation intensity incident on the wall was measured spectrally and time resolved at 11 axial planes within the spectral range of 1.4 to 5.4 μm. For numerically solving the reacting flow field, spectral methods for calculating the radiative heat transfer were coupled to fluid mechanical methods for calculating the reacting flow. The agreement between numerical prediction and measurements for the reacting flow field as well as for the radiative heat transfer is reasonably good. The numerical computations show that radiative transfer is of major importance. The temperature in the hot reaction zone was found to be lowered by approximately 400 K by radiative losses.

Sign in / Sign up

Export Citation Format

Share Document