Electrostatic spraying is a method of atomizing a fluid using a high voltage as an atomization auxiliary device, and various spraying modes exist according to experimental parameters and viscosity. A maximum of 11 spray modes were identified according to the changes in the applied voltage and flow rate. To produce fine droplets and a uniform size, which are the advantages of electrostatic spraying, in this experiment, the Sauter mean diameter (SMD) and SMD distribution were evaluated in each spray mode of electrostatic spraying. By comparing the other spray modes with the cone jet mode, it was confirmed that the maximum difference of the SMD was less than 1.5 times and the standard deviation of the rotated and pulsed jets was 2.5 times or more. In the cone shape range, the SMD and SMD distribution according to the applied voltage confirmed that the droplet size was the smallest in the middle of the cone jet mode, and the droplet distribution was also narrow. In the cone jet mode, the droplet size increased linearly with the viscosity and flow rate. In addition, the droplet distribution range was distinctive depending on the type of fluid. In the case of the relationship between the droplet size and current, it was proven that the higher the viscosity, the higher the current value for the same SMD; furthermore, the difference in the current–SMD increase rate was insignificant. Through experiments, this work presents experimental data of SMD, SMD distribution, and current–SMD in electrostatic spray experiments under various conditions.

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Nitrogen dioxide (N2O) is a greenhouse gas that is harmful to the ozone layer and contributes to global warming. Many other nitrogen oxide emissions are controlled using the selective non-catalytic reaction (SNCR) process, but N2O reduction methods are few. To avoid future air pollution problems, N2O reduction from industrial sources is essential. In this study, a N2O decomposition and NO formation under an argon atmospheric N2O gas mixture were observed in a lab-scale SNCR system. The reaction rate and mechanism of N2O were calculated using a reaction path analyzer (CHEMKIN-PRO). The residence time of the gas mixture and the temperature in the reactor were set as experimental variables. The results confirmed that most of the N2O was converted to N2 and NO. The change in the N2O reduction rate increased with the residence time at 1013 and 1113 K, but decreased at 1213 K due to the inverse reaction. NO concentration increased with the residence time at 1013 and 1113 K, but decreased at 1213 K owing to the conversion of NO back to N2O.

As a method of fluid atomization via application of a high voltage, electrospraying forms more uniform droplets than other spraying modes. This approach involves various spraying modes depending on the applied voltage. Most previous studies on electrospraying focused on the cone jet mode, which has limited applications since the applied voltage has a narrow range. To overcome this limitation, it is necessary to consider alternative spray modes, which require an in-depth understanding of their characteristics. To compare different spray modes, an investigation was conducted based on experimental parameters and fluid properties. In this study, a total of nine modes were identified, and the droplet characteristics in four modes were compared. The maximum deviation of the Sauter mean diameter (SMD) between the spray modes was approximately 1.7 times, and the SMD standard deviation was up to 2.8 times. In addition, the conditions required to realize Coulomb fission and monodisperse distribution depending on the Rayleigh critical charge (RSD < 6.76) were compared and examined.

The Y-jet nozzle is simpler to design than other twin-fluid nozzles and has various advantages such as having a wide turn-down ratio. For this reason, it is mainly used for industrial boilers and combustion. The Y-jet nozzle comprises liquid and assist gas supply ports, a mixing chamber, where two fluids (liquid and the assist gas) are mixed, and an exit orifice. The time it takes to mix the two fluids in the mixing chamber depends on the length of the chamber, which determines the spray and particulate properties. Therefore, the mixing chamber is one of the most important factors when designing the Y-jet nozzle. The gas to liquid mass flow rate ratio (GLR) is an important variable that affects the spray characteristics of the Y-jet nozzle. In this work, a laboratory-scale Y-jet nozzle spray experimental setup was developed to perform spray experiments. In particular, we observe the spray properties in the front and right directions to observe spatial spray properties. Significant results were obtained depending on the length of the mixing chamber, the spray pattern, and the Sauter mean diameter according to the GLR. We found that a mixing chamber with longer length reduces the effect of asymmetric spray and confirm that the central axis of spray is more stable.