## 3 Results and Discussion
### Influence of Different Ventilation Conditions
#### 3.2.2 Influence of Different Ventilation Temperatures
The maximum temperature difference in three cases inside the silo did not exceed 3 \({}^{\circ}\)C. The cold front area inside the wheat pile continued to increase as the ventilation time increased. The temperature of most areas inside the wheat pile was consistent, and the area of high-temperature accumulation in the middle of the grain surface also disappeared with the increased ventilation time. However, the high-temperature area near the ventilation cage inside the wheat pile still existed. The reason for this is that the temperature of the wheat pile decreased and the vapor pressure of the air around the grain particles increased when cold air was fed into the grain pile, which promoted moisture absorption and heat release in the wheat particles. Overall, the temperature variation in three cases showed a gradual trend toward a uniform distribution. Figure 10 shows the distribution of the dry-basis moisture content in the wheat pile under continuous ventilation conditions at 15 \({}^{\circ}\)C, 17 \({}^{\circ}\)C, and 19 \({}^{\circ}\)C for 24 h. Affected by the cooling cold air, the temperature near the ventilation cage was lower than in the other regions, resulting in a change in the vapor pressure of the air inside the wheat pile. That led the equilibrium moisture content located in this area to be greater than the initial moisture content of the grain. This resulted in the phenomenon of moisture absorption of the wheat particles and the formation of an obvious re-humidification area. The moisture content of the wheat pile in this area increased from the initial 12.50% to 12.80%. Although the relative humidity of ventilation is 60%, the absolute humidity of the supplied air varies due to the different ventilation temperatures, which also affects the water transport inside the grain pile. Moreover, there is a high-temperature-accumulation area in the middle of the grain surface (as shown in Figure 7), and a high degree of moisture also accumulates in this area. The main reason for this is the wheat surface at the end of the ventilation path will exhibit significant hysteresis under the influence of ventilation. Figure 11 shows the distribution of the dry basis moisture content in the wheat pile under continuous ventilation conditions at 15 \({}^{\circ}\)C, 17 \({}^{\circ}\)C, and 19 \({}^{\circ}\)C for 48 h. Compared with the results at 24 h, the internal moisture content inside the wheat pile was been slightly reduced with the increase in ventilation time. The relatively high moisture content area located in the middle and upper part inside the wheat pile also disappeared. The reason for this is the moisture content inside the wheat pile was low in a ventilation and cooling environment, resulting in a smaller rate of moisture loss. However, the moisture content located near the ventilation cage did not reach the equilibrium moisture content, resulting in the moisture content and its coverage area increasing in this area. Moreover,  
Figure 9: Temperature distribution cloud map for 96 h of ventilation in different ventilation temperatures: (**a**) 15 \({}^{\circ}\)C; (**b**) 17 \({}^{\circ}\)C; (**c**) 19 \({}^{\circ}\)C.  
the difference in the values of the moisture content between the highest and lowest of the three cases was not very significant inside the wheat pile. But for the distribution of moisture content inside the wheat pile, the area with high moisture coverage in the middle of the grain pile was the smallest when the ventilation temperature was 15 \({}^{\circ}\)C.  
Figure 12 shows the distribution of the dry-basis moisture content in the wheat pile under continuous ventilation conditions at 15 \({}^{\circ}\)C, 17 \({}^{\circ}\)C, and 19 \({}^{\circ}\)C for 96 h. The rehumidification area inside the wheat pile still increased with the increased ventilation time, but the moisture content in the other parts inside the wheat pile gradually stabilized.