# Analysis of Rewetting Characteristics and Process Parameters in Tobacco Strip Redrying Stage
## 4 Results and Discussion
### The Effect of Relative Humidity on Moisture Content and Humidification Rate of Tobacco Strips  
The distribution and trend of tobacco strips' temperature under the conditions of the relative humidity of 85% and temperature of 55 \({}^{\circ}\)C are shown in Figure 9. The time interval is the same in Figure 9a-c, which shows the real-time temperature change and distribution of tobacco strips from the three-dimensional and lateral perspectives, respectively. The initial temperature of tobacco strips was uniform. At 1 s, in Figure 9a, the lower surface temperature of tobacco strips increased rapidly and was the highest at the edge, and a large temperature gradient began to appear in the tobacco strips, with the highest temperature being on the lower surface and the lowest on the upper surface. The reason for this is that the gas phase with a higher temperature touches the lower surface of the tobacco strips first through the external forced convection, and then disperses towards the edges. At 25 s, in Figure 9b, the temperature distribution was uneven, but the temperatures of the upper and lower surfaces were close to each other due to the gas phase blowing around tobacco strips and bringing heat to the upper surface. In addition, the temperature conduction from the surroundings to the inside is more pronounced compared to Figure 9a. At 50 s, in Figure 9c, the temperature distribution and transfer trend are similar to Figure 9b, and because the vapor is stable and sufficient, there is still a high external temperature and a low internal temperature. However, the overall temperature is close to the gas-phase temperature, and the temperature difference between the inside and outside has been reduced to 1.5 \({}^{\circ}\)C, which meets the requirements of temperature regulation in production and can be seen as a uniform temperature. Using the variation and distribution of temperature in Figure 9, the effect of temperature variation on the moisture content and humidification rate of tobacco strips can be analyzed more clearly. When the relative humidity is 85% under different temperatures, the change in the moisture content of sections A, B, and C is shown in Figure 10. This is similar to Figure 7, where there are two stages, the accelerated rise stage and the approximate constant rate increase stage; 0 s to 10 s is the accelerated rise stage, and 10 s to 50 s is the approximate constant rate increase stage. The higher the temperature, the higher the increment and the rate of the moisture content increase in each section. To explain the result, the relationship between temperature and moisture has to be analyzed. For example, at 60 \({}^{\circ}\)C, the moisture content of tobacco strips is close to 14%, which is much higher than the moisture content at other temperatures. One reason is the diffusion of the  
Figure 8: The effect of different relative humidity levels on humidification rate. gas phase into the interior after condensation on the surface; on the other hand, a higher temperature (seen in Figure 9) can increase the activity of moisture molecules. The gas phase entered the interior of tobacco strips more easily and later condensed into the liquid phase inside the tobacco strips, causing a higher incremental moisture content and the rate of increase. These findings indicate that the moisture content of tobacco strips is strongly influenced by temperature. Based on the variation in the tobacco temperature and moisture content, the humidification rate curves of tobacco strips at the relative humidity of 85% and temperatures of 50 \({}^{\circ}\)C, 55 \({}^{\circ}\)C, and 60 \({}^{\circ}\)C were analyzed, as shown in Figure 11. The effect of different temperatures on the humidification rate is similar to that seen in Figure 8 of Section 4.1 and will not be repeated here. Figure 11 shows that the higher the temperature, the greater the humidification rate, and the faster the change in the tobacco strips.