## 3 Results and Discussion
Figure 11: Comparison of collection efficiency values obtained analytic and CFD models for \(S_{y}=115\) mm, applied potential 55 kV, corona wire diameters: (**a**) \(d_{w}=0.3\) mm, (**b**) \(d_{w}=1\) mm. Figure 10: Particle tracking pathlines with respect to residence time for the case of \(d_{w}=1\) mm, 55 kV, and \(U_{int}=1\) m/s in the 230 mm wide channel. Figures 12-14 show the calculated collection efficiency variation with the particle diameters for different operating conditions in the 23 cm width channels by using \(d_{w}\) = 0.3 mm, 1 mm, and 2 mm corona wire diameters, respectively. Comparing Figures 12-14, it can be observed that the corona wire electrode diameter significantly affects the collection efficiency; larger wire diameters result in better efficiency values for all ranges of particle diameters in all considered cases. It can be clearly seen that increasing the potential value significantly increase the collection efficiencies, whereas increasing the inlet velocity magnitude significantly decreases the collection efficiencies for all the considered ranges of particles. Smaller velocity (\(U_{in}\) = 1 m/s) results in better efficiency values than a higher one (\(U_{in}\) = 2 m/s) for all cases. Collection efficiencies generally have a minimum of about 0.1-0.2 \(\upmu\)m particle size for all cases. This minimum efficiency particle size is also named as the most penetrating particle size (MPPS). Although the collection efficiency values change with the operating conditions, the range of most penetrating particle sizes (MPPS) stays almost constant. This results from the increase of diffusion charging for smaller size (\(dp\leq 1\)\(\upmu\)m) particles. It should be mentioned that the collection efficiencies for the particle diameters less than 3 \(\upmu\)m are relatively quite low than the ones for the larger particles for all the cases considered in this study. Remarkably better performance was shown by 55 kV potential cases for all the particle diameter range and the cases considered. Figure  
Figures 15-17 show the calculated collection efficiency variation with the particle diameters for different operating conditions in the 180 mm width channels by using \(d_{w}\) = 0.3 mm, 1 mm, and 2 mm corona wire diameters, respectively. Similar observations for the cases of 230 mm width channels are obtained. On the other hand, comparing the results of 180 and 230 mm width channel cases, it can be seen that the distance between the wire and the plate electrodes significantly affects the collection efficiency; smaller distance between the electrodes results in better efficiency values for all ranges of particle diameter. In both channel geometry, it can be clearly seen that increasing the potential value significantly increase the collection efficiencies, whereas increasing the inlet velocity magnitude significantly decreases the collection efficiencies for all the considered ranges of particles. It should be mentioned that the collection efficiencies for the particle diameters less than 3 \(\upmu\)m are relatively quite low than the ones for the larger particles for all the cases considered in this study. Remarkably better performance was shown by 55 kV potential cases for all the particle diameter range and the cases considered. It can be concluded that a better collection efficiency can be obtained by increasing the potential difference, decreasing the gas flow velocity, and reducing the distance between the charging and collecting electrodes. It should be considered in the design of ESP the limitations of plasma generation and the particle properties. Figure 14: Variation of the ESP collection efficiency with particle diameter for \(S_{y}\) = 115 mm, \(d_{w}\) = 2 mm, (a) \(U_{in}\) = 1 m/s, (b) \(U_{in}\) = 2 m/s. Figure 15: Variation of the ESP collection efficiency with particle diameter for \(S_{y}\) = 90 mm, \(d_{w}\) = 0.3 mm, (a) \(U_{in}\) = 1 m/s, (b) \(U_{in}\) = 2 m/s.