# Analysis of Plasma Ion Distribution and Dust Collection Efficiency of Carbon-Brush Air Purifiers
## 5 Conclusions  
In this study, an investigation was conducted on an air purifier that applies a high voltage, through experiments and simulations. Carbon brushes were applied to replace the metal applied to existing air purifiers, and a simulation was performed on the ion concentration generated from the carbon brushes. The reliability of the ion concentration distribution simulation was confirmed by comparing the simulation and experimental results. On the basis of the confirmed reliability, the ion distribution according to the number of brushes was analyzed through simulation. In addition, the error rate was compared by simulating the dust collection efficiency according to the charging number and conducting the filter one-pass test in accordance with SPS-KACA002-0132,2015. 1. In the ion distribution simulation, a carbon brush to which a negative voltage was applied was simulated, and it was confirmed that the ion distribution diffused in the ground direction. Experiments were performed to examine the reliability of the simulation. An error rate of approximately 4.3% was confirmed, thereby verifying the reliability of the simulation. 2. When the ion distribution according to the ground position and distance was examined, it was found that ions were generated from the brush and formed in the ground direction. As the distance increased, the ion concentration distribution changed. This finding confirmed that the ground position is an important variable in ion distribution analysis. Figure 16: Comparison of test results and simulations. \begin{table}
\begin{tabular}{c c c c c c c} \hline  & \multicolumn{3}{c}{**Experiment [\%]**} & \multicolumn{2}{c}{**Simulation**} & \multicolumn{2}{c}{**Error Rate**} \\ \cline{2-7}  & **1 st** & **2 nd** & **3 rd** & **Average** & **[\%]** & **[\%]** \\ \hline Case 1 & 80.9 & 82.0 & 81.6 & 81.5 & 83.2 & 2.04 \\ Case 2 & 82.0 & 81.6 & 82.3 & 82.0 & 84.8 & 3.03 \\ Case 3 & 82.1 & 83.6 & 83.3 & 83.0 & 88.2 & 5.89 \\ \hline \end{tabular}
\end{table} 
Table 8: Comparison of efficiency and error rates in the final model. 3. Dust collection efficiency was simulated on the basis of the charging number calculated according to the brush location, and the efficiency was calculated to be approximately 83.2 to 88.2% depending on the brush configuration. An increase in the number of brushes did not significantly increase the dust collection efficiency, because the particles were discharged through the outlet when the charging number was four or less and 100% of them were collected when it was five or higher. Even when the number of brushes was small, a sufficient dust collection effect could be obtained under the simulation conditions applied in this study. 4. To confirm the reliability of the simulation according to the number of brushes, equipment was designed and fabricated in accordance with the standard of the Korea Air Cleaning Association (SPS-KACA002-0132,2015), and the results were compared with the simulation results. It was found that the dust collection efficiency increased as the number of brushes increased. As with the simulation results, however, the increased rate of dust collection efficiency was not very high as the number of brushes increased. The maximum error rate from the simulation results was found to be 0.836%. 5. It was confirmed that the location of brushes is more important than the number of brushes. The center of the dust collector is judged to be the optimal location of brushes in terms of ion concentration distribution. Based on this study, it is possible to secure the optimal efficiency for future electrical air purifiers for the removal of ultrafine dust and reduce the burden of actual experiments based on simulations. In the future, it is expected that better results can be obtained by designing and simulating actual products and comparing them. Conceptualization, H.G.K., S.C.K. and L.K.K. ; methodology, L.K.K., S.C.K. and H.G.K. ; validation, Y.S.K. and L.K.K. ; software, Y.S.K. ; formal analysis, S.C.K. and L.K.K. ; investigation, Y.S.K. ; resources, Y.S.K.