## 3 Results  
### Analysis of Measurements Results  
During the measurements, the basic quantities influencing the separation process were recorded, as shown in Table 1. The average values of the measured quantities mainly indicate the electricity consumption and the efficiency of the combustion process. This can be attributed to the larger cross-sectional area of the chimney, which resulted in a slight reduction in the flue gas flow rate and in the chimney draft. Closer electrode spacing also reduced the level of high voltage required to achieve the sufficient corona effect, which led to a reduction in energy consumption. The gravimetric method of measuring the mass of particles during the measurements helped us to determine the efficiency of the collection process. During the experiments, eight measurements of PM emission production were performed on both models of separators. For each model, four measurements were made with the separator on and four with the separator off. The results of the measurements were samples of PM particles deposited on the collection filters from which we could obtain not only the mass of the particles but also visually evaluate the combustion process from an emission point of view. The individual sets of collection filters for each measurement are shown in Figure 5. \begin{table}
\begin{tabular}{c c c c c c} \hline
**ESP \({}^{\ddagger}\)** & **Temperature** & **Draft** & **Current** & **Voltage** & **Power** \\ \hline One pipe & 256 \(\pm\) 3 \({}^{\circ}\)C & 12.9 \(\pm\) 0.7 Pa & 0.8 \(\pm\) 0.1 mA & 60 \(\pm\) 0.2 kV & 50 \(\pm\) 2 W \\ Four pipes & 240 \(\pm\) 3 \({}^{\circ}\)C & 12.2 \(\pm\) 0.7 Pa & 1.2 \(\pm\) 0.1 mA & 20 \(\pm\) 0.2 kV & 25 \(\pm\) 2 W \\ \hline \end{tabular} \({}^{\dagger}\) Electrostatic precipitator model.  
\end{table} 
Table 1: Average value of basic measured parameters of the precipitation process. Based on the color of the filters capturing larger particles, with increasing time the chimney becomes clogged and the emissions gradually increase to a point when an electrostatic precipitator was used, which slowed this process slightly. From the masses of the particles deposited on the filters, a much more accurate value of emissions was calculated and given in milligrams per cubic meter; the results are shown graphically in Figure 6.  
These results show that using a standard chimney electrostatic precipitator was able to reduce the average value of PM emissions from 1011.81 to 342.03 mg.m\({}^{-3}\), which represents a separation efficiency of 66.2%. Upon closer examination of the results, we notice a remarkable tendency of increasing efficiency together with decreasing particle size. In the largest PM 10 fraction, it was only 10.2%, in the case of particles with the PM 10-2.5 fraction, it had already increased to 27.5%, and in the smallest particles the PM < 2.5 fraction had already jumped up to 68.42%. The results obtained from first measurements are satisfactory for a standard chimney separator, but despite the relatively high efficiency, we can see relatively high initial values of PM emissions. However, by using the new four-pipe model, we can see a significant decrease in the input value of PM emissions, which was further reduced by using the electrostatic precipitating effect, as shown in Figure 7.  
Figure 5: Sets of collection filters F1 PM > 10, F2 PM 10–2.5, and F3 PM < 2.5 for individual measurements of variant 1: (a) M1, (b) M2, (c) M3, (d) M4, (e) M5, (f) M6, (g) M7, and (h) M8. Figure 6: Amount of PM emissions for measurements of variant 1. The results of the measurements when using the improved separator show the average reduction of PM emissions from 416.03 to 152.83 mg.m\({}^{-3}\), at an efficiency of 63.5%. More detailed results in this case show good results for separation of larger particles while maintaining the separation efficiency of smaller particles, namely 74.2% for PM 10 and 48.4% for PM 10-2.5, and 63.9% for PM < 2.5.