A Hybrid Multi-Scale Full-Spectrum k-Distribution Method for Radiative Transfer in Inhomogeneous Gas Mixtures

2005 ◽  
Author(s):  
Liangyu Wang ◽  
Michael F. Modest
Keyword(s):  
Radiative Heat ◽  
Single Species ◽  
Gas Mixtures ◽  
Great Accuracy ◽  
New Method ◽  
Full Spectrum ◽  
Participating Media ◽  
Distribution Method ◽  
Multi Scale ◽  
Inhomogeneous Gas

A new full-spectrum k-distribution (FSK) method has been developed, which integrates the advantage of the multi-group FSK method in dealing with temperature inhomogeneities for single-species media with the advantages of the multi-scale FSK method in dealing with partial pressure inhomogeneities for gas mixtures. The new method can achieve great accuracy for radiative heat tranfer calculations in participating media with inhomogeneities in both temperature and gas concentrations. The mathematical development of the new method is described, and several sample calculations are performed to demonstrate the accuracy the new method by comparison with line-by-line calculations.

Multi-Scale Full-Spectrum k-Distribution Method for Radiative Transfer in Inhomogeneous Gas Mixtures With Wall Emission

2005 ◽  
Author(s):  
Liangyu Wang ◽  
Michael F. Modest
Keyword(s):  
Heat Transfer ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Inhomogeneous Media ◽  
Full Spectrum ◽  
Distribution Method ◽  
Multi Scale ◽  
Original Distribution ◽  
Distribution Scheme ◽  
Inhomogeneous Gas

The multi-scale full-spectrum k-distribution (MSFSK) method has become a promising method for radiative heat transfer in inhomogeneous media. In this paper an original distribution scheme is proposed to extend the MSFSK’s ability in dealing with boundary wall emission. This scheme pursues the overlap concept of the MSFSK method and requires no changes in the original MSFSK formulation. A boundary emission overlap coefficient is introduced and two approaches of evaluating the coefficient are outlined. The distribution scheme is evaluated and the two approaches are compared by conducting sample calculations for radiative heat transfer in strongly inhomogeneous media using both the MSFSK method and the line-by-line method.

A Narrow Band-Based Multiscale Multigroup Full-Spectrum k-Distribution Method for Radiative Transfer in Nonhomogeneous Gas-Soot Mixtures

2009 ◽  
Vol 132 (2) ◽  
Author(s):  
Gopalendu Pal ◽  
Michael F. Modest
Keyword(s):  
Heat Transfer ◽  
Narrow Band ◽  
Computational Cost ◽  
Single Species ◽  
Full Spectrum ◽  
Participating Media ◽  
Distribution Method ◽  
Molecular Gases ◽  
Combustion Gases ◽  
Inhomogeneous Gas

The full-spectrum k-distribution (FSK) approach has become a promising method for radiative heat transfer calculations in strongly nongray participating media, due to its ability to achieve high accuracy at a tiny fraction of the line-by-line (LBL) computational cost. However, inhomogeneities in temperature, total pressure, and component mole fractions severely challenge the accuracy of the FSK approach. The objective of this paper is to develop a narrow band-based hybrid FSK model that is accurate for radiation calculations in combustion systems containing both molecular gases and nongray particles such as soot with strong temperature and mole fraction inhomogeneities. This method combines the advantages of the multigroup FSK method for temperature inhomogeneities in a single species, and the modified multiscale FSK method for concentration inhomogeneities in gas-soot mixtures. In this new method, each species is considered as one scale; the absorption coefficients within each narrow band of every gas scale are divided into M exclusive spectral groups, depending on their temperature dependence. Accurate and compact narrow band multigroup databases are constructed for combustion gases such as CO2 and H2O. Sample calculations are performed for a 1D medium and also for a 2D axisymmetric combustion flame. The narrow band-based hybrid method is observed to accurately predict heat transfer from extremely inhomogeneous gas-soot mixtures with/without wall emission, yielding close-to-LBL accuracy.

Hybrid Full-Spectrum Correlated k-Distribution Method for Radiative Transfer in Nonhomogeneous Gas Mixtures

2008 ◽  
Vol 130 (8) ◽  
Author(s):  
Gopalendu Pal ◽  
Michael F. Modest ◽  
Liangyu Wang
Keyword(s):  
Heat Transfer ◽  
Radiative Transfer ◽  
Computational Cost ◽  
Gas Mixtures ◽  
New Method ◽  
Gas Temperature ◽  
Full Spectrum ◽  
Participating Media ◽  
Distribution Method ◽  
Combustion Gases

The full-spectrum k-distribution (FSK) approach is a promising model for radiative transfer calculations in participating media. FSK achieves line-by-line (LBL) accuracy for homogeneous media at a tiny fraction of LBL’s high computational cost. However, inhomogeneities in gas temperature, total pressure, and component-gas mole fractions change the spectral distribution of the absorption coefficient and can cause inaccuracies in the FSK approach. In this paper, a new hybrid FSK method is proposed that combines the advantages of the multigroup FSK (MGFSK) method for temperature inhomogeneities in a single gas species and the multiscale FSK (MSFSCK) method for concentration inhomogeneities in gas mixtures. In this new hybrid method, the absorption coefficients of each gas species in the mixture are divided into M spectral groups depending on their temperature dependence. Accurate MGFSK databases are constructed for combustion gases, such as CO2 and H2O. This paper includes a detailed mathematical development of the new method, method of database construction, and sample heat transfer calculations for 1D inhomogeneous gas mixtures with step changes in temperature and species mole fractions. Performance and accuracy are compared to LBL and plain FSK calculations. The new method achieves high accuracy in radiative heat transfer calculations in participating media containing extreme inhomogeneities in both temperature and mole fractions using as few as M=2 spectral groups for each gas species, accompanied by several orders of magnitude lower computational expense as compared to LBL solutions.

A New Hybrid Full-Spectrum Correlated k-Distribution Method for Radiative Transfer Calculations in Nonhomogeneous Gas Mixtures

2007 ◽  
Author(s):  
Gopalendu Pal ◽  
Michael F. Modest
Keyword(s):  
Heat Transfer ◽  
Radiative Transfer ◽  
Computational Cost ◽  
Gas Mixtures ◽  
New Method ◽  
Gas Temperature ◽  
Full Spectrum ◽  
Participating Media ◽  
Distribution Method ◽  
Combustion Gases

The full-spectrum k-distribution (FSK) approach is a promising model for radiative transfer calculations in participating media. FSK achieves line-by-line (LBL) accuracy for homogeneous media at a tiny fraction of LBL’s high computational cost. However, inhomogeneities in gas temperature, total pressure and component-gas mole fractions change the spectral distribution of the absorption coefficient and can cause inaccuracies in the FSK method. In this paper, a new hybrid FSK method is proposed that combines the advantages of the multi-group FSK (MGFSK) method for temperature inhomogeneities in a single gas specie and the multi-scale FSK (MSFSK) method for concentration inhomogeneities in gas mixtures. In this new hybrid method the absorption coefficients of each gas specie in the mixture are divided into M spectral groups depending on their temperature dependence. New and accurate MGFSK databases are constructed for combustion gases, such as CO2 and H2O. This paper includes a brief mathematical development of the new method, method of database construction and sample heat transfer calculations for 1-D inhomogeneous gas mixtures with step changes in temperature and species mole-fractions. Performance and accuracy are compared to LBL and traditional FSK calculations. The new method achieves high accuracy in radiative heat transfer calculations in participating media containing extreme inhomogeneities in both temperature and mole fractions using as few as M = 2 spectral groups for each gas specie, accompanied by several orders of magnitude lower computational expense as compared to LBL solutions.

Reverse Monte-Carlo Ray-Tracing Method Combined With Full-Spectrum K-Distribution Method for Radiative Heat Transfer

2008 ◽  
Author(s):  
Xiaojing Sun ◽  
Philip J. Smith
Keyword(s):  
Heat Transfer ◽  
Monte Carlo ◽  
Ray Tracing ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Radiative Transfer Equation ◽  
Computational Effort ◽  
Simulation Methods ◽  
Full Spectrum ◽  
Distribution Method

Accurate prediction of radiative heat transfer plays a key role in many high temperature applications, such as combustion devices and fires. Among various simulation methods, the Monte-Carlo Ray-Tracing (MCRT) has the advantage of solving the radiative transfer equation (RTE) for real gas mixtures with almost no approximations; however, it has disadvantage of requiring a large computational effort. The MCRT method can be carried out with either the Forward MCRT or the Reverse MCRT, depending on the direction of ray tracing. The RMCRT method has advantages over the FMCRT method in that it uses less memory, and in a domain decomposition parallelization strategy, it can explicitly obtain solutions for the domain of interest without the need for the solution on the entire domain.

A Parametric Case Study in Radiative Heat Transfer Using the Reverse Monte-Carlo Ray-Tracing With Full-Spectrum k-Distribution Method

2009 ◽  
Vol 132 (2) ◽  
Author(s):  
Xiaojing Sun ◽  
Philip J. Smith
Keyword(s):  
Heat Transfer ◽  
Monte Carlo ◽  
Ray Tracing ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Reverse Monte Carlo ◽  
Full Spectrum ◽  
Distribution Method ◽  
Mesh Resolution ◽  
Emitting Media

A combined method of reverse Monte-Carlo ray-tracing with full-spectrum k-distribution (FSK) for computing the radiative heat transfer is applied to an extreme nonhomogeneous case (both temperature and gas mixture composition vary with positions) with an absorbing, emitting media. The parameter studies of the scaled FSK (FSSK) and correlated FSK (FSCK) methods for the case, such as g point resolution, mesh resolution, reference states, and integration quadratures, are carried out. The results from the FSSK and FSCK are only affected by the chosen reference states and are not sensitive to other parameters.

Sign in / Sign up

Export Citation Format

Share Document