Successful application of plasma-activated water (PAW) as an alternate source of nitrogen for agricultural application requires low specific energy consumption. This work reports on a dielectric barrier discharge (DBD) plasma reactor for the generation of PAW having low specific energy (SE) consumption. The SE to produce N in PAW was 3.26 GJ/kg of N, which is 68% lower than the lowest value reported to date for DBD-PAW systems. The PAW generated was characterized for its physico-chemical parameters, most of which showed a linear increase with activation time (ta). The concentration of hydrogen ion and that of the nitrate, which is the desired product for agricultural application, remained stable for four weeks in the PAW. The results indicate that minimal reactive oxygen species was formed in the plasma zone and only reactive nitrogen species (RNS) was formed confirming selectivity toward RNS.
This work investigates the reliability of the function called ‘regionprops’ which is used for measuring the 2D length of the plasma discharge. Work was conducted in a Rotating Gliding Arc (RGA) reactor, using air as plasma forming gas. Arc rotational images at three different gas flow rates i.e. 5, 25 and 50 litres per minute
LPM
were captured using high speed camera with an exposure of 100 μs. A total of 6799 images from all the three flow rates were considered for analysis. The 2D length of the discharge was measured by two methods namely, (a) ‘regionprops’ function (Python) and (b) manual tracing (ImageJ). The 2D arclength measured using ‘regionprops’ function matched very closely to that measured by manual hand tracing technique using ImageJ tool. A linear relation between both the methods was observed for all the three flow rates, with the coefficient of determination i.e. R
2 > 0.9 . The validation of ‘regionprops’ function shown in this work marks an important step as the function is simple to use and adapt compared to any other techniques such as shortest–path algorithm.
This work reports average electron temperature (Te) and electron density (ne) of an atmospheric argon rotating gliding arc (RGA), operated in glow-type mode, under transitional and turbulent flows. Both Te and ne were calculated near the shortest (δ) and longest (Δ) gap between the electrodes, by two different methods using two separate measurements: (1) optical emission spectroscopy (OES) and (2) physical–electrical. Te calculated from (a) collisional radiative model (CRM) (OES) and (b) BOLSIG+ [physical–electrical, reduced electric field (ENo) as input], differed each other by 16%–26% at δ and 6% at Δ. Te was maximum at δ (>2 eV) and minimum near Δ (1.6–1.7 eV). Similarly, the ENo was maximum near the δ (5–8 Td) and minimum near Δ, reaching an asymptotic value (1 Td). By benchmarking Te from CRM, the expected ENo near δ was corrected to 3 Td. The calculated CRM intensity agreed well with that of the measured for most of the emission lines indicating a well optimized model. The average ne near δ and Δ from Stark broadening (OES) was 4.8–8.0×1021 m−3, which is an order higher than the ne calculated through current density (physical–electrical). Te and ne were not affected by gas flow, attributed to the glow-type mode operation. To the best of authors’ knowledge, this work reports for the first time (a) an optimized CRM for RGAs (fine-structure resolved), (b) the poly-diagnostic approach to estimate plasma parameters, and (c) the validation of ENo calculated using physical–electrical measurements.
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