Experimental and Numerical Study of the Fuel-NO_x Formation at High CO₂ Concentrations in a Jet-Stirred Reactor

Abstract

New experimental results of the characteristics of fuel-NO x formation at high CO2 concentrations are obtained in a jet-stirred reactor. NH3 is selected as the source of N. The effects of the CO2 concentration (0–97.4%), reaction temperature (873–1323 K), equivalence ratio (0.56–1.61), initial NH3 concentration (10–1000 ppm), and residence time (0.01–10 s) on the production and destruction of fuel-NO x are experimentally and numerically investigated in both N2 and CO2 atmospheres. Under fuel-lean conditions, the NO emissions decrease with increasing residence time, equivalence ratio, or CO2 concentration. Under stoichiometric conditions, the NO production from the N2 and CO2 atmospheres are nearly the same, irrespective of the temperature. Under fuel-rich conditions, the NO-reburning chemistry can reduce the majority of the NO emission. Under fuel-rich conditions and at temperatures above 1200 K, the NO production is lower in the N2 atmosphere because the NO-reburning is stronger than that in the CO2 atmosphere. Moreover, the critical temperature for the peak N2O formation is obtained. Although fuel oxidation is slightly delayed at high CO2 concentrations, the N2O formation is essentially insensitive to the CO2 concentration. Furthermore, the numerical results are consistent with the vast majority of experiments, and important reactions are identified for future development of fuel-NO x formation at high CO2 concentrations.

Comparative Study between Flameless Combustion and Swirl Flame Combustion Using Low Preheating Temperature Air for Homogeneous Fuel NO Reduction

“…10a are consistent with our previous experiments. 48 Figure 10a shows that the predicted NO emissions from the combustion of CH 4 /NH 3 agree well with the JSR experiments of CH 4 /NH 3 combustion. Therefore, the JSR calculation with the reaction mechanism can quantitatively predict the results.…”

“…46 The predictions with the mechanism on the fuel NO and NO reburning agree well with the JSR experiment. 48 More specifically, the skeletal mechanism 46 obtains better fuel NO prediction relative to other mechanisms such as the GRI based mechanism (i.e., GRI-Mech 3.0 or 2.11), 49 KONNOV mechanism, 50 or Polimi mechanism. 51 The in situ adaptive tabulation algorithm with an error tolerance of 10 −5 is used.…”

“…46 This mechanism has been comprehensively validated against both large experimental data sets and detailed mechanisms for fuel NO prediction in our previous study. 46 The ability of the mechanism for fuel NO production has been well-validated with experiments in a jet-stirred reactor (JSR) 48 and in an IFRF furnace. 46 The predictions with the mechanism on the fuel NO and NO reburning agree well with the JSR experiment.…”

“…A detailed mechanism is adopted in the PSR calculations. 48 This detailed mechanism has been systematically validated in predicting fuel NO in low oxygen conditions. 48 The PSR calculation is validated with our previous JSR experiments.…”

“…48 This detailed mechanism has been systematically validated in predicting fuel NO in low oxygen conditions. 48 The PSR calculation is validated with our previous JSR experiments. 48 The details of the JSR experiment are introduced in ref 48.…”