Due to the significant difference between temperature and grain temperature, the first ventilation time should be selected during the day to reduce the difference between grain temperature and temperature and alleviate the occurrence of condensation. In the future, ventilation should be carried out at night as much as possible, because this ventilation is mainly focused on cooling. At night, the atmospheric humidity is relatively high and the temperature is low, which reduces water loss and fully utilizes the low temperature at night, improving the cooling effect.

During the initial stage of ventilation with a centrifugal fan, condensation may occur on doors, windows, walls, and even on the surface of the grain. As long as the fan is stopped, the window is opened, the axial flow fan is turned on, and if necessary, the grain surface is turned over to remove the humid and hot air from the warehouse. Using an axial flow fan for slow ventilation will not result in condensation, only a slow increase in grain temperature in the middle and upper layers, which will steadily decrease as ventilation continues.

When using an axial flow fan for slow ventilation, due to the small air volume of the axial flow fan and the fact that grains are poor conductors of heat, slow ventilation may occur in some areas during the initial stage of ventilation. As ventilation continues, the temperature of the entire grain compartment will gradually balance.

The grain that undergoes slow ventilation must be cleaned through a vibrating screen, and the grain entering the warehouse must be promptly cleaned of the impurity area caused by automatic grading, otherwise it may cause uneven local ventilation.

5. Energy consumption calculation: The axial flow fan used in Warehouse 14 has been ventilated for 50 days, with an average of 15 hours per day, totaling 750 hours. The average moisture content has decreased by 0.4%, and the average grain temperature has decreased by 23.1 degrees. The unit energy consumption is 0.027kw. h/t. ℃. Warehouse 28 has been ventilated for 6 days, totaling 126 hours. The average moisture content has decreased by 1.0%, and the average temperature has decreased by 20.3 degrees. The unit energy consumption is 0.038kw. h/t. ℃.

The advantages of using axial flow fans for slow ventilation are: good cooling effect; Low unit energy consumption is particularly important in today's advocacy for energy conservation; Easy to control the timing of ventilation and prevent condensation from occurring; No need to equip a separate fan, convenient and flexible. Disadvantages: Due to low air volume and long ventilation time; The precipitation effect is not significant, and high moisture grains should not be ventilated with axial flow fans.

Advantages of centrifugal fans: significant cooling and precipitation effects, short ventilation time; Disadvantages: High unit energy consumption; Poor timing of ventilation can lead to condensation.

Conclusion: Axial flow fans should be used for safe, efficient, and energy-saving slow ventilation in ventilation aimed at cooling; Apply centrifugal fans in ventilation for precipitation purposes.