Nanosecond pulse discharge based nitrogen oxides treatment using different electrode configurations

Abstract

Nowadays, the intensity of air pollution, due to the industries and automobiles, has been increasing continuously. Nitrogen oxides (NO X) are one of the most harmful pollutants, which are getting released from both automobile and stationary diesel engines. They essentially need to be removed from the exhaust using after treatment systems. However, the energy required to remove these pollutants is one of the major considerations in selecting the technology for pollutant removal from diesel engine exhaust. A study has been carried out on the non-thermal plasma-based NO X removal technique using various combinations of power supply units and electrode configurations. Three different electrode configurations are tested, in which two are cylindrical electrodes with diameters 3 and 5 mm, and the other one is a square electrode with a diagonal of 5 mm. A comparison is made between the results with two different pulse power supply units, PS-I: high-voltage direct current test set based and PS-II: DC-DC converter based. The square electrode with PS-II has been found to be the optimal combination, which has removed 85% of NO X from the exhaust at an energy density of 55.5 J/L, when the initial NO X concentration in the exhaust is 388 ppm.

Augmenting NO x reduction in diesel exhaust by combined plasma/ozone injection technique: a laboratory investigation

“…Equation (20) shows the conversion of NO to NO 2 and this is predominant until the O 3 :NO is about close to one. Beyond this ratio, there will be the simultaneous production of NO 2 along with N 2 O 5 through a linking/intermediate reaction involving NO 3 formation (21) and (23). For very high ozone concentrations, though not studied in this work, wherein the ratio O 3 :NO > 2.4 there will be excess N 2 O 5 formation without any production of NO 2 leading to drooping NO 2 characteristics.…”

“…Being an active oxidising agent O 3 mainly reacts with NO forming NO 2 . It has been observed that this NO 2 formation keeps increasing as a function of ozone concentration until the ratio O 3 :NO is within a critical range (1.0-2.4) and beyond that NO 2 keeps decreasing indicating the formation of higher oxides of nitrogen such as NO 3 and N 2 O 5 (21) and (23) [10]. Therefore, our earlier definition of NO x = NO + NO 2 should now include NO 3 + N 2 O 5 .…”

“…The unreacted NO present in the plasmatreated exhaust may react with carbonyl biradicals (35) and hydrogen peroxide (39) producing mainly formaldehyde (CH 2 O)/HNO 2 . Similarly, the pathways for NO 2 conversion to higher oxides of nitrogen can be explained by (20)- (23) involving NO/NO 2 reactions with O 3 /NO 3 in which case the interpretation of NO x will not be just summation of NO + NO 2 instead it will be NO + NO 2 + NO 3 + N 2 O 4 + N 2 O 5 . However, the commercial analysers can only display NO x as NO + NO 2 .…”

Response surface methodology-based model for prediction of NO and NO2 concentrations in nonthermal plasma-treated diesel exhaust

“…If the NO X concentrations are accurately predicted through modeling, it facilitates to estimate the pollutant removal efficiencies for those parametric variations, which cannot be performed in the laboratory due to experimental limitations [1]. Experimental studies were conducted by the researchers throughout the world to know the effects of various operating parameters such as applied voltage [2,3], flow rate [4], temperature [5], residence time [6], reactor configurations [7] and electrode configurations [8]. While there is sufficient literature available regarding the chemical kinetics of the treatment, there is no much work done to quantify the effects of different parameters on the NO X removal from the exhaust.…”

Improvement of β-phase crystal formation in a BaTiO3-modified PVDF membrane

“…Plasma treatment is very efficient in fixing a variety of chemical groups on the surface of nanofillers [30], without changing their intrinsic features [31]. This treatment could be realized when gas, such as air, H 2 O, oxygen, argon, and ammonia [32], is exposed to an electromagnetic field of radio frequencies at low temperature and low voltage [33].…”