Investigation of impulsive corona discharges for energisation of electrostatic precipitation systems

Various industrial and domestic processes as well as developing nano-technologies generate micron and sub-micron particles. This phenomenon is more prevalent in large cities where population density and industrial activities are much higher, meaning that a large percentage of the world population is being exposed to everyday inhalation of particulate matter (PM). This may result in negative health effects, many of which are not investigated fully yet.
The current research project is focused on the development of a small scale impulsive micro- electrostatic precipitator (IMP) for the removal of PM at homes or in public environments, being small in contrast with the industrial ones. This IMP will implement superimposed DC and sub-microsecond electric fields in order to charge and remove PM efficiently. As the impulse breakdown voltage in a gap is much greater than the DC one, the IMP will also avoid operating close to DC breakdown voltage levels. The designed IMP system composes of a plasma-generation and particle-collection electrodes. For the former, threaded rods of 3 and 6mm have been used as well as a smooth 1.5mm one, while the latter consists of a stainless-steel tube of 28mm internal diameter. The rods were placed coaxially into the tube, with the particle laden air flowing homogenously from the top to the bottom of the reactor. The transmission line based pulse generator developed is able to produce 270ns pulses with frequency of up to 100Hz. The efficiency of precipitation of micron sized particles was evaluated for different DC and impulse voltage levels by measurements of mass of collected particles. Breakdown voltage, corona initiation voltage and parameters of impulse coronas have been obtained under different energisation regimes. Precipitation experimental results showed that the positive or negative charging regimes play an important role in the system efficiency. The ultimate objective of this research project is to investigate precipitation levels of PM2.5, which constitutes a range of lower precipitation efficiency for available ESPs, as well as potential microbiological decontamination efficiency of impulsive non-thermal plasmas.