Differential Approximation of Radiative Heat Transfer in a Gray Medium: Axially Symmetric Radiation Field

1980 ◽  
Vol 102 (4) ◽  
pp. 719-723 ◽  
Author(s):  
J. Higenyi ◽  
Y. Bayazitogˇlu
Keyword(s):  
Heat Transfer ◽  
Radiation Field ◽  
Radiative Heat ◽  
Numerical Solutions ◽  
Radiant Energy ◽  
Axially Symmetric ◽  
Differential Approximation ◽  
Emissive Power ◽  
One Dimensional ◽  
Gray Medium

The differential approximation is used to analyze an axially symmetric radiation field for a gray medium within a finite, cylindrical enclosure. The medium emits, absorbs, and isotropically scatters radiant energy and is subject to a specified heat generation. Numerical solutions are obtained for the radiative heat flux and emissive power distributions. It is found that the accuracy of the differential approximation is of the same order for the axially symmetric and one-dimensional problems.

Line-by-Line Random-Number Database for Monte Carlo Simulations of Radiation in Combustion System

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Tao Ren ◽  
Michael F. Modest
Keyword(s):  
Heat Transfer ◽  
Monte Carlo ◽  
Monte Carlo Method ◽  
Radiative Heat ◽  
Random Number ◽  
Test Cases ◽  
Combustion System ◽  
Absorption Coefficients ◽  
One Dimensional ◽  
The Monte Carlo Method

With today's computational capabilities, it has become possible to conduct line-by-line (LBL) accurate radiative heat transfer calculations in spectrally highly nongray combustion systems using the Monte Carlo method. In these calculations, wavenumbers carried by photon bundles must be determined in a statistically meaningful way. The wavenumbers for the emitting photons are found from a database, which tabulates wavenumber–random number relations for each species. In order to cover most conditions found in industrial practices, a database tabulating these relations for CO2, H2O, CO, CH4, C2H4, and soot is constructed to determine emission wavenumbers and absorption coefficients for mixtures at temperatures up to 3000 K and total pressures up to 80 bar. The accuracy of the database is tested by reconstructing absorption coefficient spectra from the tabulated database. One-dimensional test cases are used to validate the database against analytical LBL solutions. Sample calculations are also conducted for a luminous flame and a gas turbine combustion burner. The database is available from the author's website upon request.

MC Simulation of Radiative Heat Transfer Between Planar Semi-Infinite Media and Nano-Spheres With Near Field Effect

2004 ◽  
Author(s):  
Yong Huang ◽  
Xin-Gang Liang
Keyword(s):  
Heat Transfer ◽  
Radiative Heat Transfer ◽  
Field Effect ◽  
Radiative Heat ◽  
Near Field ◽  
Emissive Power ◽  
Simple Method ◽  
The Difference ◽  
Near Field Effect ◽  
Infinite Media

Based on the principle of electric dipole radiation and the Planck’s spectral distribution of emissive power, the enhancement of thermal radiation between two planar semi-infinite media or two nano-spheres was studied in this paper by the Monte Carlo method. By this simple method, some parameter’s influence on the radiative heat transfer was investigated, such as the distance between two semi-infinite media, the particle’s radius, the distance between two particles and the difference in temperature between two particles, and so on. This solution is not rigorous but simple. The results show that heat transfer can be enhanced by several orders of magnitude for the near field effect. And the radiative heat transfer is decreasing sharply with the increasing of the distance.

Use of a Zener Approximation for Heat Transfer Analyses of Quasi One-Dimensional Welding Problems

2018 ◽  
Vol 941 ◽  
pp. 2313-2318
Author(s):  
Jerry E. Gould
Keyword(s):  
Heat Transfer ◽  
Numerical Solutions ◽  
One Dimensional ◽  
Copper Electrodes ◽  
Wide Range ◽  
Linear Friction ◽  
Diffusion Transfer ◽  
Cooling Behavior ◽  
Transfer Problems ◽  
Analytical Approaches

Most welding methods in use today involve heating and subsequent cooling of the substrates for joining. Not surprisingly, understanding of associated thermal cycles implicit with the various processes has been a key facet of welding research. While the tools are available for sophisticated numerical solutions, much insight can be gained from simplified analytical approaches. A wide range of joining technologies in use today can be addressed by nominal one-dimensional heat transfer analyses. These include, for example, resistance spot, flash-butt, and linear friction welding. In addressing heat transfer problems, the mathematical constructs for heat transfer are analogous to those for mass (diffusion) transfer. Not surprisingly, one dimensional heat transfer problems can be greatly simplified by adapting the Zener approximation from mass transfer. The work described here employs the Zener approximation to address the direct spot welding of aluminum to steel. The Zener approximation is used to understand heat flow progressively from the steel into the aluminum and finally the copper electrodes. The results are used to understand weld morphology and implicit cooling behavior

Sign in / Sign up

Export Citation Format

Share Document