Publications

Selected publication  

Machala Z.: Continuous and transient electrical discharges, streamer triggered, at atmospheric pressure, for the removal of Volatile Organic Compounds (VOC), Ph.D. thesis, University Paris-Sud XI, France, Comenius University Bratislava, Slovakia, (2000).
citations: 7  

Abstract

The thesis presents two new types of streamer-induced electric discharges operating in the
non-uniform electric field in air at atmospheric pressure. These discharges are applied to the removal
of Volatile Organic Compounds (VOC) – important atmospheric pollutants. One of them is the high
pressure glow discharge (HPGD) whose exceptional feature is to be pulseless, in contrast with an
usual high pressure case to be self pulsing. It has physical properties similar to those of the normal low
pressure glow discharge. The second discharge regime, the transient spark (TS), uses the streamer-to-
spark transition. However, by limiting the spark phase to a very short time interval, it cannot reach the
local thermodynamic equilibrium. Both discharges generate a non-thermal plasma with a gas
temperature in the range of 1000 to 2000 K.
The effects of these discharges to VOC (cyclohexanone and toluene) contained in a buffer gas
(usually air) have been investigated in various reactors and under various conditions. Achieved
removal efficiencies and energy costs, as well as formed products, depend on many factors,
particularly on the injected energy (energy density), the gas components (e.g. moisture) and, of course,
on the discharge and reactor type. Optimal conditions for pollutant removal specific for each discharge
type have been determined. It is shown that mechanisms associated with heterogeneous effects of the
Cu electrode surfaces together with active nitrogen species are responsible for low energy costs (under
100 eV/molecule) and a low production of CO2 and other gaseous species, but a dominant formation
of condensed products based on amino acids.
The small pilot-scale reactor (50 Nm3/h) working with TS discharge has been successfully
applied to the removal of cyclohexanone in the mixture with other VOC, with no noxious gas output.
This validates a possibility of application of such a type of discharge reactor for larger industrial
scales.