Multidimensional numerical simulation of heat radiation in direct injection diesel engines

Author(s):  
S Chen ◽  
T. L. Chan ◽  
C. W. Leung ◽  
M. A. Liu ◽  
K. Y. Pan ◽  
...  

A multidimensional theoretical model of radiation heat transfer in the cylinder of a direct injection (DI) diesel engine has been developed, which includes submodels of heat release, geometrical description, radiation temperature, soot formation and oxidation, the absorption coefficient and the Monte Carlo method for total exchange areas. In this code, the cylinder is divided into 10 surface zones and four gas zones. The Monte Carlo method integrated with a smoothing technique considering reciprocity and conservation is used to calculate the radiation total exchange areas directly for both the absorbing—emitting media and the complex structure of the cylinder. Using the multi—dimensional approach, the variation in radiant heat transfer with crank angle can be obtained across the whole combustion chamber. The computed results are analysed and discussed in the present study, and they are found to be in agreement with the experimental results.

2007 ◽  
Vol 6 (1) ◽  
pp. 03
Author(s):  
A. Maurente ◽  
P. O. Bayer ◽  
F. H. R. França

The temperatures of the gases produced in combustion processes are very high so thermal radiation constitutes an important heat transfer mechanism in industrial furnaces. Most furnaces can be modeled as gray enclosures containing non-gray gases. The radiation heat transfer can be obtained with the aid of the weighted-sum-of-gray-gases model, determining the zonal exchange areas for each of the gray gases considered in the sum. For some enclosures with simple geometries, there are correlations to obtain the direct exchange-areas which can be used to determine the total exchange areas. However, for enclosures with complex geometries, determining the direct exchange areas can become a difficult task. In this case, the use of the Monte Carlo method is advantageous, for it allows one to approach geometric complexities without additional complications. Therefore, the method was applied to compute total exchange areas in enclosures containing participating media. Two cases were considered: cylindrical enclosures and enclosures that have generic geometries formed from cube combinations. The results presented a good agreement with solutions available in the literature.


2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Tao Ren ◽  
Michael F. Modest

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.


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