نوع مقاله : مقاله پژوهشی
1 گروه هوافضا، دانشکده علوم و فنون نوین، دانشگاه تهران
2 عضو هیات علمی/ دانشکده علوم و فنون نوین/ دانشگاه تهران
3 عضو هیئت علمی/دانشکده مهندسی هوافضا، دانشگاه صنعتی امیرکبیر
4 عضو هیئت علمی/ دانشکده مهندسی هوافضا، دانشگاه صنعتی شریف
عنوان مقاله [English]
In this study, oxy-combustion is numerically investigated under MILD conditions. This novel combination is simulated in a laboratory-scale furnace with parallel fuel and oxidant jets and a recirculating flow. With nitrogen removal from the oxidant stream, zero NOx emission for gaseous fuel systems is expected. Combustion field is modelled using a well-stirred reactor and computational fluid dynamics. In the CFD modelling, RANS equations are solved using RNG k-ε and EDC model is employed to model the turbulence-chemistry interaction. The effect of oxidizer preheating and CO2 dilution on the combustion field as well as flue gas composition is investigated. The results indicate that the flame maximum temperature does not experience a significant increase when the preheat temperature rises, positively affecting the temperature distribution at the cost of CO emission which is a direct consequence of higher recirculation and mixing rate. Also, a kinetic study on the chemical effect of CO2 presence reveals that CO production path through CH3O radical is more strengthened compared to the main path through formaldehyde when increasing the dilution level. When diluting the oxidant, methylene’s role become more influential in CO formation than when pure oxygen is used, contributing to higher CO emission. CO2 defeats CH4 and O2 to absorb the free H radicals, causing higher levels of CO production.