## 4 Discussion
### Thermal Balance Model (Applications and Future Developments)  
The combination of tests developed in this work can be used in a way adapted to different situations of measurements. As an example, we are going to cite a series of future research cases where the research group has the prospect of including these results:  
* The possibility pointed out by this work of using non-destructive tests for the thermal characterization of materials can be useful, especially considering those with difficult or no access for the installation of thermocouples that measure the evolution of temperatures during the measurement process.
* Once the thermal characteristics of a material are known, the possibility of knowing the conditions of the convection cell that is established in the surface temperature exchanges could also be interesting. This would allow, for example, obtaining data related to the behavior of the evapotranspiration phenomenon in soils and other surfaces. This is also carried out non-destructively and even without the need for contact with the medium to be analyzed.
* Given a known thermal characteristic of a material, its state can be monitored by temporal analysis of the evolution of its thermal conductivity, which can change depending on certain processes that are happening in it.
* The installation of an external heat source, such as a halogen lamp, with the role of sunlight would allow for a more realistic simulation of the scenario, in such a way that the methodology developed could also be applied to the calculation of the thermal conductivity due to radiation.  
It is possible that new applications derived from the global test presented in this work will appear, especially in the field of evaluating materials with difficulties to access them in a physical way to perform the temperature measurements required.  
As an example, a general sensitivity analysis of the thermal conductivity related to changes in the porosity is included to evaluate the geotechnical conditions of a certain material, in this case felsic rocks. As can be seen in Table 7, the thermal conductivity data for different types of felsic rocks decrease when their porosity increases, that is, when their fracturing increases. Therefore, a decrease in thermal conductivity can mean a decrease in its mechanical capabilities.  
As a way to control the stability in the structural capacities of this type of rocks, the thermal conductivity can be measured periodically with a procedure like the one described in this work.  
\begin{table}
\begin{tabular}{c c c} \hline
**Rock Type** & **Solidity (1-Porosity)** & **Thermal Conductivity (W/mk)** \\ \hline \multirow{3}{*}{Felsic rock (20\% quartz content)} & 0.5 & 1.50 \\  & 0.6 & 1.65 \\  & 0.7 & 1.85 \\ \hline \multirow{3}{*}{Felsic rock (30\% quartz content)} & 0.5 & 1.80 \\  & 0.6 & 1.90 \\  & 0.7 & 2.05 \\ \hline \multirow{3}{*}{Felsic rock (40\% quartz content)} & 0.5 & 1.95 \\  & 0.6 & 2.15 \\  & 0.7 & 2.34 \\ \hline \multirow{3}{*}{Felsic rock (50\% quartz content)} & 0.5 & 2.05 \\  & 0.6 & 2.25 \\ \cline{1-1}  & 0.7 & 2.55 \\ \hline \end{tabular}
\end{table}
Table 7: Thermal conductivities for felsic rocks with different quartz content and porosity [42].