## 3 Results and Discussion
### Experimental Evaluation of the Solar Dryer
#### 3.1.2 Plantain  
Similar to the case of taro, solar radiation had variations, albeit less significant in this case due to the presence of low cloudiness in the experiment period, improving the air temperature conditions at the entrance to the drying chamber. However, it was still not possible to keep a constant temperature of the air surrounding the fruit. Contrary to taro, plantain porosity is low, also reducing the critical moisture content in the plantain. Due to this, plantain samples have less water in the last drying stage, and their drying velocity is lower than that of taro. Similar to the case of taro, there were disturbances, but they were decreased due to better conditions of solar radiation and a decrease in the porosity of the samples. The phenomenology was similar to that which occurs in taro. The temperature gradient for hot air circulation was still achieved, establishing the conditions and behaviors of drying by evaporation and improving the drying curves, as shown in Figure 5.  
In the case of 6 V fan voltage, (Figure 5(a1,b1)), three drying time ranges were identified from 0 to 225 min, 225 to 350 min, and 350 to 465 min, with average drying velocities for each region of 1.27, 1.25, and 0.255 g/min respectively. This corresponded to the rate of variation of the dry basis moisture, which, at the beginning of drying, was observed to decrease, but not remain constant. The same behavior occurred for solar radiation, which only suffered from some disturbances at the beginning of the drying time. In Figure 5(a1), after 150 min, a behavior derived from a combination of effects was observed. On the one hand, there was a measurement error, which could be subject a change in the relative humidity of the environment. On the other hand, in the solar radiation curve, a sudden decrease of 0.735 kW/m\({}^{2}\) occurred between 2:00 and 3:00 p.m., due to the presence of cloudiness. The temperature developed in a range between 32.3 \({}^{\circ}\)C and 44 \({}^{\circ}\)C, with a morphology similar to solar radiation, except for the sudden decrease in radiation, where the slow and delayed nature of the heating process was revealed, as there was no change in temperature until after the sampling period. In the last drying stage, a decrease of 20.4% in the drying velocity was achieved, 12.6 percentage points below the taro for the same supply voltage. For the fan operating at 9 V (Figure 5(a2,b2)), two ranges of drying time were observed from 0 to 270 min and from 270 to 495 min, with average drying velocities of 1.46 and 0.36 g/min, respectively. The rate of variation of the dry base humidity ratio during the start of drying decreased and remained almost constant, thus covering a wide range of time (4.5 h). This was due to a reduction in disturbances of solar radiation, as well as the ambient temperature, reaching values between 38 \({}^{\circ}\)C and 28 \({}^{\circ}\)C, which also allowed a stabler and broader decreasing drying region of almost 3.75 h, with an average drying velocity of 0.36 g/min and a 25% reduction in drying velocity, 36 percentage points below the taro for the same supply voltage. In the case of the fan at 12 V, (Figure 5(a3,b3)), three ranges of drying time were presented from 0 to 200 min, 200 to 345 min, and 345 to 435 min, with average drying velocities for each region of 1.95, 0.79, and 0.12 g/min, respectively. It was observed that disturbances only occurred in the solar radiation curve in the second region of the drying time, with a negative peak of 0.232 kW/m\({}^{2}\) between 11:00 and 11:30 a.m.; with these exceptions, solar radiation and ambient temperature maintained their relative morphology, with a range between 27.9 \({}^{\circ}\)C and 36 \({}^{\circ}\)C, helping the drying process. On the other hand, in the last stage of a decrease in drying, the average drying velocity was 0.12 g/min, with a reduction in drying velocity of 15.4%, 29.9 percentage points below the taro for the same feed voltage.