An extended weighted-sum-of-gray-gases model to account for all CO2 ‐ H2O molar fraction ratios in thermal radiation

Hadi Bordbar*, Guilherme C. Fraga, Simo Hostikka

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

7 Citations (Scopus)


All published weighted sum of gray gases models (WSGGM) were either developed for a limited number of molar fraction ratios, MR, or include MR as a variable in their formulations. Either way, they are not able to adequately support moisture-rich regions of combustion environments, such as the outer regions of unwanted fires, fires during water-based suppression, and some air-injection regions of furnaces. In this article, we provide an extension to a previously published WSGGM by coupling it to a new accurate set of WSGGM coefficients for pure carbon dioxide and water vapor. The coupling follows a linear interpolation methodology, which is justified by a detailed analysis of the line-by-line (LBL) absorption spectra and by plotting the total emissivity of CO2 ‐ H2O mixtures with large and small values of MR for various temperatures and path lengths. The proposed model is discussed and validated in four benchmarks, using a solution obtained by LBL integration as reference. The results indicate that, while the previously available WSGGMs either have excessive computational costs or yield inaccurate results in the regions of large MR, the new model can be safely used for all gas compositions in a computationally efficient manner.

Original languageEnglish
Article number104400
Number of pages7
Publication statusPublished - 1 Jan 2020
MoE publication typeA1 Journal article-refereed

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  • Projects

    Novel measurement and sensing technologies for thermal radiation of unwanted fires

    Hostikka, S., Isojärvi, T., Naji Nassajfar, M. & Bordbar, H.


    Project: Academy of Finland: Other research funding

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