期刊
FUEL
卷 283, 期 -, 页码 -出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.fuel.2020.118773
关键词
Furnace; Homogeneous combustion; Industrial; Swirl; NOx
资金
- NSF [1403339]
- Department of Mechanical Engineering, University of Michigan, Ann Arbor
- Div Of Chem, Bioeng, Env, & Transp Sys
- Directorate For Engineering [1403339] Funding Source: National Science Foundation
This study numerically investigates the effectiveness of localized swirling injection in enhancing reactant dilution for an HC combustor operating with enriched oxidizers. The results show that swirling injection has effects on the flow field and NOx emissions, with an optimal swirl intensity for reducing NOx emissions. Competition between swirl-assisted and entrainment-driven dilution is observed, indicating a trade-off relationship in terms of NOx emissions.
Conceptually similar to MILD, FLOX, CDC, HiTAC, etc., Homogeneous Combustion (HC) continues to be pursued as an appealing technique towards minimizing NOx emissions. HC combustors are generally driven by high-momentum inlet jets which enable intense dilution of the reactants. This work numerically studies the effectiveness of localized swirling injection in enhancing reactant dilution for an HC combustor running with enriched oxidizers (X-O2 > 21%). Even though localized and low intensity, swirling injection is found to have far-field effects (over similar to 75 diameters). Effects of swirling injection on the flow field (near and far field) and on NOx emissions are explained. While swirl does help in reducing NOx, there exists an optimal swirl intensity beyond which NOx emissions increase. A mutual competition is seen between swirl assisted and entrainment driven dilution; and at higher swirl intensities, the reduction in the latter overwhelms the gains accrued by the former (in terms of NOx emissions). Along expected trends, thermal NOx is deduced to be the dominant pathway of NOx formation for oxy-enriched cases. Damkohler numbers in the reaction zone are low even for the highest oxygen content tested here (X-O2 = 40%). Volumetric standard deviation of Heat Release Rate (HRR) is seen to perform well as a measure of the tendency of transition to the conventional mode of combustion.
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