A Study of NO_x Reduction by Acoustic Excitation in a Liquid Fueled Burner

Abstract

This paper presents the results of a controlled acoustic excitation of a liquid fueled non-premixed flame as a means of nitric oxide reduction. The experimental burner is a domestic hot-water heater provided by Viessmann. An actuator is located on the air duct and comprises two perforated plates. By changing the speed of rotation of the rotor it is possible to achieve a single frequency excitation of the burner cavity. The industrial version of the burner already features low NO, exhaust levels (82 ppm at 0% 0₂)and satisfies the current European regulations concerning pollutant emissions. Its operating point corresponds to an equivalence ratio of 0.82. It is shown that for a broad range of frequencies (100 Hz to 700 Hz) the overall nitric oxide emissions are reduced up to 15%. Radical imaging of the excited flames shows strong effects of the excitation on the flame geometry, especially on the flame length, and gives guidelines to a new, more effective, NO., emission control using acoustic excitation.

Keywords:

• Pulsating combustion
• diffusion flames
• NO.reduction

Notes

Present affiliation: IMF Toulouse, 31400 Toulouse Cedex, France.