Abstract
The large temperature difference between the radiation source and the condensed materials in fire scenarios, makes the general form of full spectrum correlated-k method unable to accurately model both absorption and emission within the condensed phase. In this paper, a new solution form for the FSCK method is presented which accurately accounts for both. This so-called “separated” form of FSCK method solves the contributions of medium emission and boundary's incident intensity separately by implementing two different reference temperatures. The advantages of the separated FSCK method is exhibited through three case studies using the transmissivity and radiative heat source calculated by high resolution line by line calculations as the benchmark. The test cases represent a layer of six different liquid and solid hydrocarbon fuels for which the various levels of irradiation from a radiating source is introduced by the temperature of its upper wall and an effective emissivity. The case studies provide a sensitivity analysis for the magnitude and spectral form of the irradiation at the boundary. The separated form of FSCK exhibits its best performance when the incident intensity and medium emission are in the same order of magnitude. Moreover, when the peak region of the boundary's spectral irradiation is closer to the peaks of the absorption coefficient spectrum of the condensed phase, the accuracy of both separated and classical FSCK solutions decreases, though, the separated solution still provides better accuracy.
Highlights
The recent progress in computational resources paved the road for high fidelity numerical modeling of complex physical phenomena occuring in energy conversion processes such as multiphase flows [1,2] and thermal radiation [3,4]
Spectral radiative heat transfer in gaseous combustion products has been extensively studied in past years and several methods such as weighted sum of gray gases (WSGG) [5,6,7], spectral line based weighted sum of gray gases (SLW) [8,9], and full spectrum correlated k-distribution (FSCK) [10,11] methods have been presented for its modeling
Taking advantage of the basic idea of the separation technique, we improve the accuracy of FSCK method in solving the radiation heat transfer within the condensed materials in combustion environments
Summary
The recent progress in computational resources paved the road for high fidelity numerical modeling of complex physical phenomena occuring in energy conversion processes such as multiphase flows [1,2] and thermal radiation [3,4]. It was shown that by using the flame temperature as the reference temperature in FSCK calculations of liquid heptane and toluene, the liquid emission is not accurately solved [18] It triggered the motivation of the current work to improve the accuracy of FSCK method in the simulation of both absorption and emission within the condensed materials. The new formulation of FSCK presented in the current work is based on separating the contributions of medium emission and irradiation at boundary of a condensed material layer. The history of this idea goes back to the work by Olef [19] in introducing a modified differential approximation for solving the RTE within gaseous media.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
