Radiative properties and radiative heat transfer calculations for high temperature combustion gases

Combustion in fires and in commercial combustion systems produces substantial amounts of heat and locally high temperatures, making radiation an important mode of heat transfer for most combustion applications. Unfortunately, spectral modeling of molecular gas radiation remains a difficult task to this day due to inadequate knowledge of radiative properties of important participating gases and lack of efficient and accurate radiation models.; A highly successful global model, the Full-Spectrum k-distribution (FSK) model, was developed in this thesis, extending the concept of narrow band k-distributions to the entire spectrum by introducing a fractional Planck function. The treatment of nonhomogeneous media was comprehensively discussed and optimized, concentrating on the approach of Correlated (Full-Spectrum Correlated k-Distribution Model) and/or Scaled absorption coefficients (Full-Spectrum Scaled k-Distribution Model).; For strongly nonhomogeneous media, the Full-Spectrum k-distribution model was extended to multi-scale and multi-group gases. In the multi-scale approach (MSFSK), the spectral lines of individual gases were broken up into different scales according to their lower level energies, or different species in a gas mixture were simply separated. An approximation was introduced to account for the overlap of the absorption coefficient between different scales. In contrast, in the multi-group approach (MGFSK), spectral locations were sorted into several spectral groups, according to their absorption coefficient dependence on (partial) pressure and temperature, resulting in no overlap between different groups.; A thorough investigation of the absorption coefficient dependence on temperature and partial pressure was done for the two most important combustion gases, CO₂ and H₂O. Based on the Multi-Group approach, state-of-the-art databases were constructed, making it possible to achieve any desired accuracy for the radiative heat transfer calculations in combustion systems, at the price of just a few spectral calculations.