Development and Testing of a Cold-Plasma Reactor for Diesel Exhaust Gas Treatment

This work describes the development and testing of a cold-plasma reactor utilising a pulsed corona discharge, in order to reduce environmentally harmful combustion by-products commonly found in Diesel exhaust gas. The corona discharge was generated by the application of a $\sim 70 \mathrm{kV} \mathrm{HV}$ pulse to the reactor by means of a Blumlein pulse generator. The combustion by-product compounds produced from a Diesel burning boiler were measured with a flue gas sensor positioned down-stream from the reactor. The HV pulse applied had a positive or negative polarity, and was varied from a pulse repetition frequency (PRF) of 1Hz up to 40Hz. With a negative HV pulse, the combustion by-product concentration decreased monotonically, with the largest decrease observed in $\mathrm{NO}_{\mathrm{x}}\left(\mathbf{2 9 \%}\right.$), followed by SO
2
$(21 \%)$, and finally by $\mathrm{CO}_{2}(16.5 \%)$ at a PRF of 40 Hz. The results presented clearly display the distinct action of high energy electrons emitted from a pulsed negative corona discharge, which effectively reduce the concentration of Diesel combustion by-products.