Application of the Multi-Spectral Correlated-K Distribution Model for Oxy-Fuel Combustion

Abstract

Thermal radiation is dominant in oxy-fuel combustion technology. When considering the difference between conventional air combustion and burgeoning oxy-fuel combustion caused by diverse components of fuel gas, it is critical to improve the accuracy of numerical simulation for radiation by CFD. The line-by-line model is considered as the most accurate approach to simulate thermal radiation while it will cost vast calculation resources on the other hand. This approach is applied as a benchmark for the validation of other approximate models in most cases. The corrected-K distribution method (CK) has attracted considerable attentions in recent years. the NBCk model always has an excellent performance when the temperature gradients are small. However, when the temperature gradient gets higher, the correlation assumption breaks down and leads to non-negligible errors. To improve the accuracy of the CK model, we introduced a new method called the multi spectral corrected-K distribution model based on the functional data analysis (FDA) in this work. The objective of this MSCK method is to group together wavenumbers according to the spectral scaling functions defined as the ratio between spectra in different thermophysical states. Over these intervals, the correlation assumption can be considered as nearly exact. Results show that the MSCK model always achieves a better performance on calculation accuracy while sharing the same computational cost as the traditional CK model.