Updated correlation of the absorption line blackbody distribution function for H2O based on the HITEMP2010 database

The absorption line blackbody distribution function (ALBDF) was developed for use in global methods such as the SLW and FSK models that integrate the radiative transfer equation over the absorption coefficient rather than wavenumber. A widely used method of representing the ALBDF efficiently is a correlation in the form of a hyperbolic tangent function originally proposed by Denison and Webb. This paper reports on the generation of new coefficients to be used in the correlation for H2O using the recently released high temperature database, HITEMP2010. The updated correlation is valid for an expanded temperature range, from 400 to 3000 K, made possible by the new database. The accuracy of the new coefficients is tested and compared against the previous correlations through calculations of total emissivity and the Planck mean absorption coefficient. Solutions of the radiative transfer equation in homogeneous one-dimensional media have been performed with the SLW method using the updated ALBDF, and are compared to rigorous line-by-line calculations. The updated correlation performs very well in these calculations and shows excellent accuracy compared to the line-by-line benchmark predictions. Comparisons made with the previous coefficients show that updating the correlation was necessary in order to obtain accurate calculations. -- Highlights: ► HITEMP2010 was used to update the absorption line blackbody distribution function. ► Hyperbolic tangent form used previously was maintained. ► Temperature ceiling was extended from 2500 K up to 3000 K. ► Calculations using the updated correlation demonstrate its accuracy. ► Comparisons with the previous correlation demonstrate the need for an update