## 3 Results and Discussion
### Influence of Drying Temperature  
The dependence of moisture content on drying temperature can be taken into account indirectly, for example, by changing the coefficient \(k\) in [PERSON]'s model. This issue was studied in more detail, for example, in [19], where, in particular, for modeling the drying of one of the materials at temperatures of 35, 45 and 55 \({}^{\circ}\)C, the values of coefficient \(k\) 0.34, 0.049 and 0.016, respectively, were obtained. A similar approach is used in [15]. Thus, the coefficient \(k\) summarizes the effect of temperature and other technological features of drying. Obviously, it is important for practice to know the influence of each factor on the drying process [1, 22, 23, 24, 25]. However, this is a difficult task. Let us consider a simple model in which the drying temperature and initial moisture content are separately taken into account; the influence of other factors is modeled in total. Let's use the results presented above to study one of the possible approaches to model building, taking into account the drying temperature in a thin layer. Restricting ourselves to the option of drying at a positive temperature, we can assume that in relation (11), the value of \(\Delta M_{\textit{water}}\) is proportional to the amount of water \(M_{\textit{water}}\) and the drying temperature \(T\)\({}^{\circ}\)C (in this work, the drying temperature is assumed to be a constant value; to take into account the temperature, a dimensionless coefficient \(\phi=T\)\({}^{\circ}\)C/\(T_{\textit{ref}}\)\({}^{\circ}\)C is used, where \(T_{\textit{ref}}\) is the reference temperature equal to 100 \({}^{\circ}\)C. Thus, instead of (11), we can write:  
\[\Delta M_{\textit{water}}=\frac{\Delta t}{\tau}M_{\textit{water}}\phi \tag{23}\]  
For substantiating relation (23), one can additionally refer to the work [26], (p. 11), according to which the change in the moisture content of the material is directly proportional to the temperature of the air for drying. Regarding the coefficient \(\phi\), note that the value of \(T_{\textit{ref}}=100\)\({}^{\circ}\)C is chosen to obtain the coefficient in dimensionless form. In the particular case under consideration, the choice of \(T_{\textit{ref}}\) is not critical, i.e., another suitable value may be used, since possible deviations will be compensated by the above parameter \(\tau\). However, all temperature values in the considered model are assumed to be positive. Using (23), following the logic of obtaining relations (14)-(18a), we write down relations (24)-(28):  
\[\Delta M_{\textit{water}}=\Delta\theta M_{\textit{water}}\phi \tag{24}\]  
\[\tilde{C}_{\textit{water}}^{(w.b.)}=\frac{C_{\textit{water}}^{(w.b.)}-\Delta \theta\phi C_{\textit{water}}^{(w.b.)}}{1-\Delta\theta\phi C_{\textit{water}} ^{(w.b.)}} \tag{25}\]  
Figure 6: Normalized dimensionless characteristics: moisture content (w.b. ), drying rate module and drying process acceleration. \[\Delta C_{water}^{(w,b)}=\Delta\theta\phi C_{water}^{(w,b)}\Big{(}1-C_{water}^{(w,b )}\Big{)} \tag{26}\]  
\[\frac{dC_{water}^{(w,b)}}{C_{water}^{(w,b)}(1-C_{water}^{(w,b)})}=-d\phi\theta \tag{27}\]  
\[C_{water}^{(w,b)}=\frac{C_{water,start}^{(w,b)}}{C_{water,start}^{(w,b)}(1-e^{ \theta\phi})+e^{\theta\phi}} \tag{28}\]  
By analogy with (18a), we transform (28) to the form (28a):  
\[C_{water}^{(w,b)}=\frac{e^{-\theta\phi}}{\Big{(}C_{water,start}^{(w,b)}\Big{)}^ {-1}+e^{-\theta\phi}-1} \tag{28a}\]  
Using (28a), we find the moisture content \(C_{water}^{(d,b)}\) by using Equation (8). By analogy with (22), let us determine the normalized values of moisture content in the form of ratios \(C_{water}^{(w,b)}/C_{water,start}^{(w,b)}\), \(C_{water}^{(d,b)}/C_{water,start}^{(d,b)}\). Note that the models considered in this paper belong to the class of models of drying in a thin layer [1]. In models of drying a material in a thin layer, it is assumed that the temperature and moisture content of the material almost does not change over its thickness.