1, because the temperature and grain temperature difference is great, the first ventilation time should be chosen during the day, in order to reduce the gap between grain temperature and temperature, and reduce the occurrence of condensation. After the ventilation as far as possible in the evening, because the ventilation is to cool at night, humidity is relatively high, low temperature, so that reduce the water loss, and make full use of the night temperature, improve the cooling effect.
2, in the early days of centrifugal fan there may be a door and window and wall condensation, even slight condensation of surface grain surface, as long as the wind stop machine, open the window, open the axial fan, if necessary, changes the grain surface, the positions within the hot air outside the warehouse can be excluded. When the axial fan is used for the slow ventilation, there will be no condensation. Only the upper and middle grain temperature will rise slowly, and the grain temperature will decrease steadily as the ventilation continues.
3, with the advantages of axial flow fan ventilation: slow cooling effect is good; the unit energy consumption is low, is particularly important in advocating energy conservation today; ventilation time is easy to grasp, not prone to condensation; not alone with a fan, convenient and flexible. Disadvantages: due to the small air volume and long ventilation time, the effect of precipitation is not obvious, and the high moisture grain should not be ventilated by axial flow fan.
Slow ventilation 4, axial flow fan, the axial fan air volume, and food is a poor conductor of heat, ventilation early prone to individual parts of ventilation ventilation continued to slow, with full grain storage temperature will gradually balance.
5. The grain for slow speed ventilation must be cleaned by vibrating screen, and the grain in the warehouse must be cleaned in time, and the impurity area caused by automatic grading will be easy to cause partial ventilation uneven.
6, the advantages of centrifugal fan, cooling, precipitation effect, ventilation time is short; disadvantages: high energy consumption; ventilation timing bad dewing.
7. Conclusion: in the ventilation with the purpose of lowering temperature, the axial fan is adopted for the safe, efficient and energy-saving slow speed ventilation, and centrifugal fans are applied in the ventilation for precipitation purposes.
8, energy consumption calculation: No. 14 warehouse with axial fan ventilation for 50 days, an average of 15 hours per day, sharing 750 hours, the average water dropped by 0.4%, grain temperature dropped by an average of 23.1 degrees, unit energy consumption is 0.027kw.h/t. degrees centigrade. No. 28 warehouse accumulated ventilation for 6 days, sharing 126 hours, the average water dropped by 1%, the average temperature dropped by 20.3 degrees, the unit energy consumption is 0.038kw.h/t. degrees centigrade.