## 3 Results and Discussion  
### Level of Homogeneity of the Surface Temperature  
The CFD simulations of the different configurations make it possible, among other things, to show the level of homogeneity achieved in the air temperatures inside the air chamber. These simulations have been performed by imposing an air temperature of 300 K in the inlet section and a lower surface temperature of 310 K. Figure 6 shows temperature maps in which the color darkens as the temperature increases. Since the inlet air has a lower temperature than that of the lower surface of the air chamber, it heats up as it travels from the inlet section to the outlet section. The more efficient the heat exchange is between the surface and the air, the faster the surface will heat up, and therefore, more dark-colored areas will be seen in these figures. From the first visual analysis, it is clear that configurations 1.3, 3.1, and 3.2 are the ones with the greatest homogeneity and the highest ratio of dark to light surfaces. Furthermore, comparing them with each other, 3.1 distributes the light-colored zones over the entire surface (i.e., low temperatures), while in 3.2 and especially 1.3, the lower temperatures are more concentrated in the vicinity of the entrance section. It should be noted in this regard that, in addition to homogeneity in air temperatures and efficiency in heat exchange, it is desirable that the cold zones are as evenly distributed as possible over the entire surface.  
Figure 5: Case 1.1 (a), Case 1.2 (b), Case 1.3 (c), Case 1.4 (d), Case 2.1 (e), Case 2.2 (f), Case 2.3 (g), Case 3.1 (h), and Case 3.2 (i).  
An analysis of the frequency of air temperature in the grid cells allows us to quantify the above results for each case. Thus, as Figure 7 shows, Cases 1.4 and 3.2 present the highest mean air temperature (dashed lines), as well as a frequency distribution more skewed towards high temperatures (solid lines). As can be seen, these two cases have very similar results. For ease of representation, one case of each type has been selected for this figure, all of them having been simulated with an inlet velocity of 1 m/s and temperatures of 300 K and 310 K at the inlet section and the bottom surface, respectively.  
Figure 6: Different cases under study: CFD maps of air temperature Case 0 (**a**), Case 1.1 (**b**), Case 1.2 (**c**), Case 1.3 (**d**), Case 2.1 (**e**), Case 2.2 (**f**), Case 3.1 (**g**), and Case 3.2 (**h**).  
Both the mean temperature and the air temperature distribution depend on the air velocity. Figure 8 compares the results for 0.5, 1, and 1.5 m/s in the inlet section for Case 3.2. The results show that the lower the temperature, the more skewed to the right the temperature frequency distribution, and therefore, the higher the average air temperature in the air chamber. Although increasing the inlet air velocity from 0.5 to 1 m/s slightly reduces the mean air temperature, increasing it from 1 to 1.5 m/s has little effect on it.  
Table 1 lists the results of the CFD simulations in terms of the heat fluxes that the air takes from the bottom surface of the air chamber and the pressure drop experienced by the air as it passes from the inlet section to the outlet section. The first columns contain the results obtained for an air velocity at the inlet of 1 m/s for all cases. In Case 0, the reference case, and the cases of greatest interest, 1.4, 3.1, and 3.2, simulations have also been performed at 0.5 and 1.5 m/s to analyze the influence of air velocity.  
Figure 8: Air temperature frequency of grid cells as a function of air inlet velocity.  
Figure 7: Air temperature frequency of grid cells as a function of the case.