# Nonthermal Plasma Multi-Reactor Scale-Up Using Pulse Capacitive Power Supplies
## 3 Results and Discussions
### NTP Mini-Reactor Scale-Up Using R-C Pulse Generator (RCG)  
As in the previous case, four reactors connected to work in parallel were considered to demonstrate the feasibility of the simultaneous operation of a large number of impulse discharges generated by the RC pulse-type power supply. Figure 12 presents the schematic of the four reactors connected in parallel. The best results regarding the discharge stability were obtained for capacitors charging up to 65% of maximum voltage (on the linear charging slope of the capacitor voltage) corresponding to charging time constant T = RC. The breakdown voltage can be adjusted in this case by modifying the distance between the electrode air gap of the reactors. Figure 11: Four discharges working in parallel for CCL type of NTP mini-reactor. Figure 10: CCL-type NTP multi-reactor current waveforms—zoomed-in view on one set of current pulses. Figure 14 shows that all four pulses (the current for the four reactors II, I2, I3, and I4) of the discharges were in phase, indicating that all the discharges were evolving at the same time. Figure 14: Current waveforms of R–C pulse generator (RCG)—zoomed-in view of one set of four pulses (I1, I2, I3, I4). Figure 13: Current waveforms of the four RCG reactors working in parallel—the current for the four reactors (I1–I4). Similar to the previous case, Figure 15 demonstrates the simultaneous evolution of the four NTP generating discharges. In this case, the current of all four reactors again evolved simultaneously, demonstrating the feasibility of scaling up the NTP reactor system to industrial scale. The frequency of the pulses was 600 Hz, the input power was about 8 W, and the energy transfer efficiency in this case was about 38-40%. The energy efficiency transfer can be optimized, depending on the electrical parameters of the electrical schematic. The pulse duration in this case was 0.5 ms. The frequency and the power of the discharge could be adjusted by modifying the value of the capacitor and/or the resistance of the RC circuit. This leads to the possibility to control the PAW chemical composition without modifying the gas or water flow rates. In order to compare the efficiency of the three types of power supplies for NTP mini-reactors (RCG, CCL, and ICR), deionized (DI) water was treated in all three configurations with Ar as the carrier gas, while the concentration of hydrogen peroxide (Figure 16) and the H\({}_{2}\)O\({}_{2}\) energy efficiency (EEf\({}_{\rm H2O2}\); Figure 17) were calculated. EEf\({}_{\rm H2O2}\) represents the quantity of the H\({}_{2}\)O\({}_{2}\) generated in water (in grams) for 1 kWh of energy used. In our case, EEf\({}_{\rm H2O2}\) was calculated considering the input power of the NTP reactors. As shown in Figures 16 and 17, the hydrogen peroxide production in the ICR reactor was higher than that in the capacitive current limited CCL reactor and RCG; on the contrary, the energy efficiency production of hydrogen peroxide (EEf\({}_{\rm H2O2}\)) was almost two times higher in the RCG reactor than in the other two NTP reactors (ICR and CCL). Table 1 presents the pulse energy and electrical efficiency for the proposed power supplies. The electrical efficiency represents the ratio between the energy delivered to the discharge and the input energy of the power supply. For the ICR case, the total electrical power was the highest in the range of 26 W, but it had the lowest electrical efficiency of only 12% to 15%. The highest electrical efficiency was found to be in the case of RCG power supply. The values presented in Table 1 can vary, being subject to the chemical/physical conditions of use of the reactors. Figure 15: The four RCG reactors working in parallel. Figure 16: H\({}_{2}\)O\({}_{2}\) production in ICR, CCL, and RCG reactors with Ar.