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Although removal of NOx by (pulsed) corona discharges has been thoroughly investigated for high concentrations of NOx in flue gas, removal of low levels in ambient air proves to be a difficult task. (Sub) ppm NOx levels exist in traffic tunnels due to accumulation of exhaust gases. The application of pulsed corona technology for purification of traffic tunnel air is studied during a series of lab and field experiments. An industrial pilot scale wire-cylinder type corona reactor has been utilized. Lab tests have been carried out using a diesel generator as NOx source. NOx conversion levels have been determined by applying two Recordum Airpointers (chemiluminescence-based detection). The detector appeared to be cross-sensitive for HNO3 and high levels of O3. NOx removal rates of 60-80% were obtained for inlet levels of 2-10 ppm. The SIE value of 10 ppm NOx removal is 7 J l-1. The corona discharges produce ppm level NOx at high energy densities. This intrinsic NOx production limits removal of inlet levels due to equilibrium between production and oxidation. [ABSTRACT FROM AUTHOR]

In this paper we investigate temperature and pressure effects on the properties of a positive pulsed streamer plasma. We use a corona plasma setup in which we vary the temperature between 303 and 773K at atmospheric pressure and the pressure between 37.9 and 100 kPa at room temperature to achieve the same neutral gas density and compare electrical and optical (ICCD imaging) measurements carried out in both experiments. From the measurements we found that the dissipated plasma energy and the average streamer propagation velocity are both higher for the temperature experiments at the same neutral gas densities as in the pressure experiments. This suggests the existence of a specific temperature effect. A possible explanation for this effect is a higher streamer conductivity at high temperatures, as was previously found in the literature. [ABSTRACT FROM AUTHOR]