## 2 Methodology of the Study
### Drying Kinetics and Energy Intensity  
Drying kinetics were evaluated on the basis of drying curves, that is, changes in dimensionless moisture content over time, and changes in drying rate as a function of dimensionless moisture content. In addition, the average drying rate was also determined for each process.  
By defining the dry basis moisture content as the ratio of the mass of moisture (\(m_{w}\)) contained in the material to the mass of the dry phase (\(m_{d}\)) [28]:  
\[X=m_{w}/m_{d}, \tag{1}\]  
the drying kinetics of samples could be assessed in terms of dimensionless moisture content (\(Y\)) and drying rate (\(DR\)) in accordance with the following equations [29]:  
\[Y_{i}=\overline{X}(t_{i})/X_{0}, \tag{2}\]  
\[DR_{i}=-m_{d}(dX/dt)=-(dm_{w}/dt)=-(m(t_{i})-m(t_{i-1}))/(t_{i}-t_{i-1}), \tag{3}\]  
where \(\overline{X}(t_{i})\) is the spatial average of the moisture content determined at time \(t_{i}\), \(X_{0}\) is the initial moisture content, \(dm_{w}\) is the weight loss of the sample, and \(dt\) is the time at which the weight loss \(dm_{w}\) occurred.  
The mass of moisture \(m_{w}\) can be defined as the difference between the mass of the moist material \(m\) and the mass of the dry phase \(m_{d}\). After substituting this difference into (1) the spatial average moisture content \(\overline{X}(t_{i})\) (dry basis) at any \(i\)-th time of the process was calculated using the following formula [30]:  
\[\overline{X}(t_{i})=(m(t_{i})-m_{d})/m_{d}, \tag{4}\]  
where \(m(t_{i})\) is the sample mass measured at time \(t_{i}\), and \(m_{d}\) is the dry matter determined using a Precisa XM120 moisture analyzer (Dietikon, Switzerland) with an accuracy of 0.01%.  
The average drying rate for a given drying process was calculated using the following equation [30]:  
\[DR_{w}=\Delta m/DT, \tag{5}\]  
where \(\Delta m\) is the mass of moisture removed from the sample by drying, and \(DT\) is the total drying time.  
The experimental data was also used to determine the drying constant, \(k\); mass transfer coefficient, \(\alpha\); and effective diffusion coefficient, \(D_{\textit{off}}\). All these parameters could be determined from the drying rate curves [30]. Based on the experimental results, the values of the average moisture content \(\left(\overline{X}\right)_{i}\) and the rate of moisture content change \(-\left(d\overline{X}/dt\right)_{i}\) were calculated in accordance with the following equations [30]:  
\[\left(\overline{X}\right)_{i}=\left(\overline{X}(t_{i})+\overline{X}(t_{i-1}) \right)/2, \tag{6}\]  
\[-\left(d\overline{X}/dt\right)_{i}=\left(\overline{X}(t_{i-1})-\overline{X}(t _{i})\right)/(t_{i}-t_{i-1}), \tag{7}\]  
The rate of moisture content change \(-\left(d\overline{X}/dt\right)_{i}\) (7) was calculated as an average value for the time period \((t_{i}-t_{i-1})\). For consistency in kinetics modeling, material moisture content \(\left(\overline{X}\right)_{i}\) (6) was also averaged over the same time period \((t_{i}-t_{i-1})\). Based on the linear approximation of the moisture content change over average moisture content, the drying constant, \(k\), was determined to be the slope of approximation lines. The mass transfer, \(\alpha\), and the effective diffusion coefficient, \(D_{\textit{off}}\), were then calculated using the following formula [30]:  
\[\alpha=kl, \tag{8}\]\[D_{eff}=\left(4l^{2}k\right)/\pi^{2}, \tag{9}\]  
where \(l\) is half of the sample's thickness.  
Each drying schedule was also assessed in terms of energy intensity. The total electric energy consumed by the experimental setup during the drying tests was measured using an electricity meter. The resulting electricity consumption, \(EC\), was then transformed through recalculation into specific energy consumption, \(SEC\), that is, the amount of energy used to evaporate one kilogram of moisture according to the relationship:  
\[SEC=\left(3.6\cdot EC\right)/\Delta m, \tag{10}\]  
The value thus determined enabled the energy consumption of each process to be compared.