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Show interaction with the plasma, must be separated in order to determine if the application of plasma technology to NOx control is the means by which the high NOx reduction was achieved in the demonstration experiments. Once this plasma effect is verified, further experiments designed to explore the fundamentals of the plasma process for NOx control will be necessary to gather infonnation to scale up and optimize the process for commercial application. This paper presents the results of an experiment designed to distinguish the thermal effect from the radical (or plasma) effect in the plasma-assisted ammonia injection process for NOx control, and it introduces a new experiment underway designed to explore the process on a more fundamental level. In the completed experiment, the lab-scale apparatus used in previous demonstrations of the process was modified by replacing the plasma system for ammonia radical injection with a system to inject hot NH3 and a carrier gas. In this way, NOx reduction by the thermal effect was allowed, but NOx reduction by the radical effect was prevented, such that the two effects could be separated and quantified. In the new experiment, opposing jets of plasma gas and NOx-laden gas will be used in conjunction with an analytical model of the system to gain insight into the process fundamentals. Hot Injection Experiment Design To isolate the thermal effect from the radical effect in the plasma-assisted ammonia injection process for NOx control, an experiment using hot NH3 injection was designed to mimic conditions in previous work by Zhou et. al .. The relative NOx reduction advantage of hot NH3 to cold NH3 injection, a measure of the thennal effect, was investigated directly. The advantage of .plasma injection over hot NH3, a measure of the radical effect, was inferred by duplic.ating conditions from the previous work, using hot injection instead of the plasma system. Figure 1 shows the overall apparatus used in Zhou's plasma experiments and in the hot injection investigations. The combustor and the fuel injector measured 15 cm and 1 cm in diameter, respectively, and the length of the combustion chamber was 150 cm. A methane diffusion fl~e was doped with nitric oxide (NO) to raise the NO concentration in the combustor for study. The ammonia, carrier gas, and combustion gas flow rates used in the plasma and hot injection experiments were identical. NO and NOx concentration measurements were made with a Thenno-Electron 10AR chemiluminescent NOINOx analyzer. Gas flow measurements were made with rotameters, and temperatures were measured with Chromel-Alumel (Type K) thennocouples. 3 |