## 3 Results and Discussion
### Evaluation of the Combustion of the Briquettes  
For this analysis, 1 kg of each fuel was placed in the combustion chamber under the metallic plate. Each sample was ignited with 50 g of _cote_ (wood impregnated with pine resin, _Pinus leiophylla_), which were introduced simultaneously in the three combustion chambers to systematize the experiment and ensure adequate ignition (Figure 9). Figure 10 shows the results of the thermographic analysis conducted at 20 min after initial combustion. According to the radiative thermographic spectrum, the combustion of the briquettes and the pine and oak firewood reached maximum temperatures of 330.2 \({}^{\circ}\)C, 178.1 \({}^{\circ}\)C, and 327.2 \({}^{\circ}\)C, respectively, during the first combustion period of 20 min. Figure 10d shows that all three fuels emitted energy in the form of a radiant body, where all the temperatures emitted in a given area are observable. This figure reveals that the briquettes had a radiative thermographic spectrum with temperatures of 54.8-335.6 \({}^{\circ}\)C, while the pine firewood reached temperatures between 69.2 and 102 \({}^{\circ}\)C, and the oak firewood a range of 102-215 \({}^{\circ}\)C. Figure 10e  
Figure 10: Combustion at 20 min: (**a**) briquette; (**b**) pine firewood; (**c**) oak firewood. (**d**) Integrated image of the three fuels; (**e**) emissions in the form of radiant bodies from the three fuels. Figure 9: Combustion of the three fuels tested: (**a**) briquette; (**b**) pine firewood; (**c**) oak firewood. presents an integrated image to compare the three fuels. In this stage, the briquette emitted the highest thermal yield at 321.1 \({}^{\circ}\)C.  
Figure 11 presents the thermal yield of the three fuels analyzed after 45 min of combustion. In that period, the briquettes and pine and oak firewood reached maximum temperatures of 335.7, 336.8, and 323.6 \({}^{\circ}\)C, respectively. This analysis found that the three fuels emitted energy in the form of a radiant body in a given area. The briquettes and pine and oak firewood reached temperatures of 87.0-335.9 \({}^{\circ}\)C, 54.8-335.9 \({}^{\circ}\)C, and 49.7-335.9 \({}^{\circ}\)C, respectively. This image was taken after 50 min of combustion. Figure 12 presents the thermal yield achieved by the fuels after 70 min of combustion. The radiative thermographic spectrum shows that the briquette reached a maximum temperature of 232.1 \({}^{\circ}\)C, while the pine and oak firewood had maximum temperatures of 214.7 and 265.1 \({}^{\circ}\)C, respectively. Figure 11: Combustion at 45 min: (**a**) briquette; (**b**) pine firewood; (**c**) oak firewood. (**d**) Integrated image of the three fuels; (**e**) emissions in the form of radiant bodies from the three fuels. Figure 12: Combustion at 70 min: (**a**) briquette; (**b**) pine firewood; (**c**) oak firewood. (**d**) Integrated image of the three fuels; (**e**) emissions in the form of radiant bodies from the three fuels. Figure 12d shows the three fuels analyzed. In this stage, the oak firewood had the highest thermal yield, emitted at 336.7 \({}^{\circ}\)C. Figure 12e presents the energy emission in the form of radiant bodies emitted by the three fuels in a given area. Here, the briquettes emitted a temperature of 56.2-338.2 \({}^{\circ}\)C, the temperature for the pine firewood was 60-338.2 \({}^{\circ}\)C, and for the oak firewood it was 51.0-338.2 \({}^{\circ}\)C. The termination of the combustion process, after a time interval of 1 h and 50 min, can be observed. Figure 13b shows the energy emission in the form of radiant bodies. The temperature range in this stage was determined to be 49.1-262.0 \({}^{\circ}\)C.  
This thermographic analysis allowed us to determine the velocities of the ignition, combustion, and degradation of the materials during total combustion. Compared to traditional fuels, _Pinus_ spp. and _Quercus_ spp., the briquettes of this research easily combustion, have a long burning time, and their calorific power is corroborated with the useful energy for a domestic task (heating water).