The role of axial flow fan and centrifugal fan in mechanical ventilation

1. Due to the large difference between the temperature and the grain temperature, the first ventilation time should be in the daytime to reduce the grain temperature difference and mitigate the generation of condensation. The future ventilation should be carried out at night as far as possible, because the ventilation is mainly for cooling, and the air humidity at night is relatively high. Low temperature reduces the water consumption, makes full use of the low temperature at night, and improves the cooling effect.

2. Doors and windows may appear at the initial stage of centrifugal fan ventilation Wall condensation, or even slight condensation on the surface particle surface, as long as the fan is stopped, the window is opened, the axial flow fan is turned on, and the grain surface is turned over when necessary to remove cold and wet gas from the warehouse. The axial flow fan will slowly ventilate without condensation, and only the middle and upper grain temperature will rise slowly. With the continued ventilation, the grain temperature will decline steadily.

3. When the axial flow fan is used for slow ventilation, the grain is a poor conductor of heat due to the small air volume of the axial flow fan. In the initial stage of ventilation, ventilation is slow in some places. With the continuous ventilation, the grain temperature of the whole warehouse will gradually balance.

4. The grain with slow ventilation needs to be cleaned by vibrating screen. The grain in the warehouse must be cleaned in time from the impurity area caused by automatic classification, otherwise it is easy to cause uneven local ventilation.

5. Calculation of energy consumption: No. 14 warehouse is ventilated by axial flow fan for 50 days, with an average of 15 hours a day, and the level drops by 00 hours. 4. The average grain temperature drops by 23.1 degrees, and the unit energy consumption is 0.027 kw. h/t. ℃. The No. 28 warehouse has been ventilated for 6 days in total, 126 hours in total. The level has dropped by 1.0, the average temperature has dropped by 20.3 degrees, and the unit energy consumption is 0.038 kw. h/t. ℃.

6. Advantages of axial flow fan for slow ventilation: good cooling effect; The unit energy consumption is low, so it is important to advocate energy conservation; The ventilation time is easy to master and not easy to condense; No independent fan, convenient and flexible. Defect: due to small air volume, long ventilation time; The rainfall effect is not obvious, and the axial flow fan is not suitable for ventilation.

7. Advantages of centrifugal fan: cooling The rainfall effect is significant, and the ventilation time is short; Defect: high unit energy consumption; The ventilation time is not easy to condensation.

8. Conclusion: Axial flow fan is safe for desuperheating ventilation Efficient, energy-saving and slow ventilation; Centrifugal fans are used for rainfall ventilation.