Narrow Band k-Distribution Model for Radiative Calculations of Non-Gray Gas

Abstract

Based on precise mathematical principles, a narrow band k-distribution (NBK) model is developed to calculate the radiative properties of water vapor and carbon dioxide. In this model, the integral variable of radiative transfer equation (RTE) is transformed from wavenumber to non-dimensional cumulative k-distribution function, leading to a final integration with very few quadrature points. Accuracy of the model is examined by calculating radiation in gases between two cold and black parallel plates. All the parameters calculated through NBK model, including radiative flux, transmissivity as well as radiative intensity, are compared with that of line-by-line calculations, which proves the NBK model can provide exact results with great computational savings. In this paper, absorption coefficients of water vapor and carbon dioxide are obtained from the line parameters in high-resolution spectroscopic database HITEMP 2010.