## 3 Results and Discussion
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**\(P\) (W)** & **CO\({}_{2}\)max (\%)** & **CO\({}^{max}\) (\%)** & **H\({}_{2}\)max (\%)** & **CH\({}_{4}\)max (\%)** \\ \hline
840 & 7.02 \(\pm\) 0.95 & 7.51 \(\pm\) 1.06 & 0.3 \(\pm\) 0.06 & 3.52 \(\pm\) 0.75 \\
1760 & 8.91 \(\pm\) 1.02 & 8.95 \(\pm\) 0.87 & 1.8  
particular, experiments have shown that the average yield of CO and CO\({}_{2}\) remained practically unchanged when the microwave power was increased from 840 to 1760 W. However, with a further increase in power to 2200 W, there was a significant increase in the average yield of CO and CO\({}_{2}\) (2.5 and 1.4 times, respectively). The formation of methane and hydrogen (according to the average yield) showed a higher sensitivity to an increase in the microwave power. An increase in power by 2.6 times contributed to an increase in the average yield of CH\({}_{4}\) by 5 times and H\({}_{2}\) by 3.8 times. A significant difference between the average yields of pyrolysis gas is explained by the different intensities of wood decomposition at different microwave exposure powers and, as a result, different reaction times (Figure 4b). At 2200 W, the process time was about 30 min, while at 840 W, the release of pyrolysis gases was completed in 50 min. To compare the results of microwave and conventional pyrolysis of biomass, [38] was considered. In [38], the traditional pyrolysis of sawdust was performed in a laboratory reactor. The average yield of conversion gas products was as follows: CO\({}_{2}\)--14%; CO--10%; H\({}_{2}\)--3.2%; CH\({}_{4}\)--less than 0.4%. These values are comparable to those obtained for microwave pyrolysis of sawdust. Microwave pyrolysis provided a significantly lower release of carbon dioxide (an undesirable conversion product); however, the average yield of CO and H\({}_{2}\) was lower than that in conventional pyrolysis (1.2 and 4 times, respectively). Also, during conventional pyrolysis, the average methane yield was significantly lower than that during microwave conversion at 2200 W. However, the differences in the experimental conditions should be considered. In particular, in [38], the heating of the raw material was gradual, from 25 \({}^{\circ}\)C to 500 \({}^{\circ}\)C for about 50 min, while microwave pyrolysis required about 600 s of operation of the magnetron at a power of 2200 W.  
According to the experimental data, approximation formulas (Equations (1)-(5)) were determined for calculating the yield of individual components of the pyrolysis gas from woody biomass:  
\[\text{O}_{2}=-0.0012P+17.547 \tag{1}\]  
\[\text{CO}_{2}=0.001P+2.478 \tag{2}\]  
\[\text{CO}=0.0031P-0.024 \tag{3}\]  
\[\text{H}_{2}=0.0004P-0.134 \tag{4}\]  
\[\text{CH}_{4}=0.0014P-0.73 \tag{5}\]  
The approximation formulas were obtained using OriginPro software. Curve fitting tools made it possible to calculate an equation that describes the experimental points according to the least squares rule (to minimize the total deviation of the curve from  
Figure 4: Average yield of pyrolysis gas components (**a**) and characteristic times of the process (**b**) with varying microwave power. the points). It is important to note that the same experimental data can be described by different equations. Therefore, when analyzing the data, we were also guided by the fact that the equation should be fairly simple (not of a high order). This is important for further application of formulas, convenience of working with them, and reduction in computational costs. All approximation formulas given in the work describe specific experimental data obtained in experiments. The area of their proven applicability is the power variation range of 840-2200 W. With a certain degree of assumptions, the equations can be used to predict the characteristics of microwave pyrolysis over a wider range and to model processes. However, this requires experimental verification. Figure 4b shows the characteristic times of the process under study at different microwave powers.