Flamelet tabulation methods for solid fuel combustion with fuel-bound nitrogen

This work develops flamelet tabulation methods for solid fuel combustion with and without fuel-bound nitrogen based on computations in particle-laden counterflow flames. The proposed flamelet tabulation methods for NO prediction are evaluated for two different coal types. The results show that extracting the NO mass fraction from the flamelet library directly results in significant discrepancies in the studied fuel nitrogen-free flame, while reasonable predictions can be obtained by using the same method in the fuel-bound nitrogen flames for both coal types. In contrast, solving a transport equation for the NO mass fraction tends to improve the NO prediction. The NO concentration is well predicted by splitting the NO source term into a formation part and a rescaled consumption part. The best NO prediction is obtained by extracting the formation part and the rescaled consumption part with a modified reaction progress variable.