2.3.2. Chemical Properties

Proximate analysis (PA) was calculated using a mu ffle furnace following the standards [20–22]. Ultimate analysis (UA) was calculated using a Vario MACRO Cube Elementar Analyzer. The heat release by the unit of mass during the combustion of RS and RH was evaluated through the higher heating value (HHV) using the empirical expression [23]:

$$\text{HHV (M)} / \text{Kg} = 0.3536 \text{ FC} + 0.1559 \text{ V} \\ M - 0.0078 \text{ A} \tag{2}$$

With the fixed carbon (FC), volatiles (VM), and ash (A) content in mass percentage.
