## 3 Results
### Calorific Value  
Based on the data obtained with the adiabatic calorimeter, the average values of the upper calorific value (HCV) of 17,260 kJ/kg and lower (LCV) of 17,010 kJ/kg were obtained for an average moisture content of briquettes of 4%. With the help of the previous relationship (8), the calorific value for absolutely dry briquettes (at a moisture content of 0%) was found to be 17,690 kJ/kg. Using some elements of linear geometry (generating a linear equation through two points), the two relationships of the high and lower calorific power (LCV = 17,690-170\(\cdot\)Mc; HCV = 17,690-107.5\(\cdot\)Mc) were found, with the help of which the graph in the following figure was created (Figure 5).  
It was observed that, with the increase in the moisture content of the briquettes, the calorific value of HCV and LCV decreased. Significant decreases in yield below 42% were observed after a value of 60% moisture content. A maximum moisture content of 10% for coated briquettes is, therefore, recommended when the calorific efficiency is over 94%. By means of linear geometry, an intersection with the horizontal axis of the two linear equations  
Figure 4: Empirical Cumulative Distribution Function (CDF) for splitting strength of briquettes: T1 briquettes without voids with a diameter of 59 mm; T2 briquettes without voids with a diameter of 71 mm; T3 briquettes with inner hollows.  
Figure 5: The influence of moisture content on the calorific value for straw briquettes: red line-HCV, blue line-LCV.  
was found for the value of 104% in the case of LCV and 164.5% for HCV. These moisture content values, for which the calorific value is zero, point to some limiting values when the energetic effect is zero; that is, the amount of heat obtained through combustion is equal to that consumed for drying the wood briquettes. These values obtained on the basis of the graph in Figure 5 are referred to as the limiting moisture content of combustible materials.  
The calorific value obtained per hectare of cultivated wheat, obtained with the help of (9), was 91,988 MJ/ha.  
The calorific value of wheat straw was also modeled according to the carbon content. As shown by other authors [27; 29; 43], wheat straw has a lower carbon content than wood at 47.9%. This low carbon content is translated into a lower calorific value. Correspondence between the calorific value and the carbon content is, therefore, necessary to take into consideration, along with wheat straw, European beech wood (_Fagus sylvatica_ L.) and wood charcoal obtained from beech wood. The dependency relationship developed by [PERSON] and [PERSON] [18; 19; 43], adapted to the requirements of this modeling, was used:  
\[\text{CV}=33.910\text{-C}+11.783\text{-H}+1.034\text{-O}-0.211\text{\text{ \text{\text{\text{\text{\text{M}}}}}}}\text{\text{\text{\text{\text{\text{ \text{M}}  
In this way, a new equation was obtained for determining the calorific value depending on the carbon content of lignocellulosic biomass, which can be quickly used to determine the calorific value (Equation (16)):  
\[\text{CV}=0.366\text{-C}+1.318\ \text{[MJ/kg]} \tag{16}\]  
For example, to analyze reed biomass with a 42.41% carbon content [13], by applying (16), we find a calorific value of 16,840 MJ/kg. The carbon content obtained per 1 ha of wheat was between 1.1 and 3.9 t/ha, in agreement with the results of others [13].