Application of approximations for joint cumulative k-distributions for mixtures to FSK radiation heat transfer in multi-component high temperature non-LTE plasmas

Approximations for joint cumulative k-distribution for mixtures are efficient for full spectrum k-distribution (FSK) computations. These approximations provide reduction of the database that is necessary to perform FSK computation when compared to the direct approach, which uses cumulative k-distributions computed from the spectrum of the mixture, and also less computational expensive when compared to techniques in which RTE's are required to be solved for each component of the mixture. The aim of the present paper is to extend the approximations for joint cumulative k-distributions for non-LTE media. For doing that, a FSK to non-LTE media formulation well-suited to be applied along with approximations for joint cumulative k-distributions is presented. The application of the proposed methodology is demonstrated by solving the radiation heat transfer in non-LTE high temperature plasmas composed of N, O, N2, NO, N2+ and mixtures of these species. The two more efficient approximations, that is, the superposition and multiplication are employed and analyzed.

► Approximations for joint cumulative k-distributions are efficient for FSK computations. ► Application of these approximations is extended here to non-LTE media. ► For applying the approximations to non-LTE media, a new FSK for non-LTE formulation is proposed. ► Two efficient approximations, the superposition and multiplication, are employed and analyzed.