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ISSN Online: 2377-424X

International Heat Transfer Conference 12
August, 18-23, 2002, Grenoble, France

Development and examination of radiative heat transfer calculation method considering the narrow band non-uniformity and the coexistence of H2O and CO2

Get access (open in a dialog) DOI: 10.1615/IHTC12.4960
6 pages

Abstract

This paper proposes a rational method for properly incorporating the temperature-dependent variation of band shape and the influence of narrow-band nonuniformity into numerical predictions of radiative heat transfer in infrared-active gas even if the field is non-isothermal. Also the case where CO2 and H2O coexist was discussed. Examination into the band model suggested that we had better use the absorption coefficient and line overlap parameter truly representing each narrow band instead of those evaluated by a wide band model. Based on this recognition, discussion was concentrated on the treatment of the narrow band non-uniformity. The validity of the proposed method is confirmed by comparing its results with the results obtained from the line-by-line analyses based on a database of absorption lines. Such comparisons illustrated the following things. The Elsasser model is applicable to an arbitrary narrow band of H2O by selecting the optimum value of line overlapping parameter for each narrow band. Even if the optical path is non-isothermal, the proposed method can well simulate the transmission process, averaged over a narrow band, of both gas-originated and wall-originated radiative energy. Assumption of no correlation between the narrow band spectra of CO2 and H2O gives good evaluations of the narrow band emittance for the gas mixture containing these species. Then, we proposed a replacement of CO2/H2O mixture by a single equivalent gas for suppressing computation load. Also the validity of the calculation method based on this replacement was confirmed through comparison with the line-by-line analyses.