Radiative Heat Transfer in High-Pressure Laminar Hydrogen-Air Diffusion Flames Using Spherical Harmonics and K-Distributions

2012 ◽  
Author(s):  
Jian Cai ◽  
Shenghui Lei ◽  
Adhiraj Dasgupta ◽  
Michael F. Modest ◽  
Dan C. Haworth
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Water Vapor ◽  
Spherical Harmonics ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Diffusion Flames ◽  
Transport Equations ◽  
Full Spectrum ◽  
Air Jet

Radiative heat transfer is studied numerically for high-pressure laminar H2-air jet diffusion flames, with pressure ranging from 1 to 30 bar. Water vapor is assumed to be the only radiatively participating species. A full spectrum k-distribution spectral model is used. Narrowband k-distributions of water vapor are calculated and databased from the HITEMP 2010 database, which claims to retain accuracy up to 4000K. The full-spectrum k-distributions are assembled from their narrowband counterparts to yield high accuracy with little additional computational cost. The radiative transfer equation (RTE) is solved using various spherical harmonics methods, such as P1, simplified P3 (SP3) and simplified P5 (SP5). The resulting partial differential equations as well as other transport equations in the laminar diffusion flames are discretized with the finite-volume method in OpenFOAM. Differential diffusion effects which are important in laminar hydrogen flames are also included in the scalar transport equations. It was found that peak flame temperature becomes less sensitive to radiation at higher pressure, and that radiation causes cooling in the downstream region. Differences between the three spherical harmonics RTE solver were found negligible below 5 bar.

scholarly journals High fidelity radiative heat transfer models for high-pressure laminar hydrogen–air diffusion flames

2014 ◽  
Vol 18 (6) ◽  
pp. 607-626 ◽  
Author(s):  
Jian Cai ◽  
Shenghui Lei ◽  
Adhiraj Dasgupta ◽  
Michael F. Modest ◽  
Daniel C. Haworth
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Diffusion Flames ◽  
High Fidelity ◽  
Air Diffusion ◽  
Transfer Models

Numerical Investigation of Soot Formation in Turbulent Diffusion Flames Using Moss-Brookes Model

2014 ◽  
Author(s):  
Mannedhar Reddy ◽  
Ashoke De
Keyword(s):  
Heat Transfer ◽  
Absorption Coefficient ◽  
Radiative Heat Transfer ◽  
Turbulent Diffusion ◽  
Radiative Heat ◽  
Diffusion Flames ◽  
Soot Formation ◽  
Effective Absorption Coefficient ◽  
Turbulent Diffusion Flames ◽  
Air Jet

In the present work, two different turbulent diffusion flames are investigated for soot predictions using the presumed shape multi-environment Eulerian PDF (EPDF) as turbulence-chemistry closure. In this approach, the chemical equation is represented by multiple reactive scalars and finite number of Delta functions are used to describe the shape of joint composition PDF, while the truncated series expansion in spherical harmonics (P1 approximation) is used to solve the radiative heat-transfer equation. The absorption coefficient is modeled using the weighted sum of gray gases model (WSGG) considering four fictitious gases. The soot volume fraction is predicted using acetylene based soot inception model (Moss-Brookes model). The model accounts for inception, surface growth and oxidation processes of soot. An equilibrium based approach is used to determine the OH radical concentration, required for soot oxidation. A single variable PDF in terms of temperature is used to include the turbulence-chemistry effects on soot. An effective absorption coefficient is calculated to include the influence of radiative heat transfer on soot. The combined tool is used to determine the soot formation in two hydrocarbon flames (Delft flame III, pilot stabilized natural gas flame and an unconfined C2H4/air jet flame). The soot formation rate decreases with the inclusion of radiation for both the flames and indicate the need for delineation of radiative heat transfer. The effects of soot-turbulence interaction are consistent with available literature. The effect of collision efficiency on oxidation rate can be clearly explicated from the predictions of C2H4/air flame.

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.

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.

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