Study On The Property Of Transverse Ventilation And The Application Effect Of The Warehouse

This paper designed a small ventilation device, which can change ventilation direction(transverse ventilation and vertical ventilation) by transforming the position of the ventilation box, while the grain heap state invariant. In order to change the ventilation types(positive presseure ventilation, negative presseure ventilation), we can change the connection position of the air duct. Meanwhile, under different ventilation conditions, ensure the openporosity, grain thickness, ventilation way are the same, to make the experiment more scientific and reasonable.In this paper, using the small ventilation device to study the ventilation performance of wheat, paddy, corn, soybean under different types of ventilation. Through the frequency converter set 14 HZ, 23 HZ, 32 HZ, 41 HZ, 50 HZ to adjust the wind speed, and then mensurate the static pressure of grain heaps. The results show that: Under different ventilation conditions, static pressure value and the depth of the grain heap showed a linear relationship. In the four grain heaps, the wind speed of positive presseure ventilation is greater than negative presseure ventilation’s, while the static pressure of positive presseure ventilation is smaller than negative presseure ventilation’s. In the heap of wheat, paddy and corn, the wind speed of transverse ventilation is greater than vertical ventilation. the static pressure of transverse ventilation is smaller than vertical ventilation’s. However, the wind speed and the static pressure are similar under horizontal ventilation and vertical ventilation in the soybean heap. When the ventilation condition and frequency converter are the same, the static pressure of wheat heap is the biggest, soybean heap’s is the least, corn heap’s and paddy heap’s are similar.The resistance of the unit grain layer was calculated according to the static pressure value in the grain heaps. Using software to get the curve fitting. It is found that the mathematical model of unit grain layer resistance can be described by quadratic function and power function. Power function has the advantages of simple structure, could meet the requirements of engineering calculation, quadratic function is more accurate. Under the same wind speed, the unit grain layer resistance of vertical ventilation is greater than transverse ventilation’s in the heap of wheat, paddy and corn. However, the unit grain layer resistance of transverse ventilation and vertical ventilation in soybean heap is similar. When the direction of ventilation(transverse ventilation and vertical ventilation) are the same, the unit grain layer resistance of negative presseure ventilation is greater than that of positive presseure ventilation in the four kinds of grain. The effect of ventilation types on the resistance of unit grain layer is greater than the direction of ventilation. The heap of wheat, rice and corn are anisotropic. Because soybean shape is approximately ball, the ventilation process does not reflect the anisotropy.Under the condition of vertical ventilation, the resistance of unit grain layer: wheat>corn>paddy>soybean, the unit grain layer resistance of wheat is far greater than the other three kind of grains, the unit grain layer resistance of corn and paddy are close. Under the condition of vertical ventilation, the unit grain layer resistance: wheat>paddy>corn>soybean.Ventilation uniformity was positively correlated with the frequency and the depth of the grain heap. The uniformity of the vertical ventilation is larger than transverse ventilation’s in the wheat and paddy, and the corn heap is just the opposite. The uniformity of transverse ventilation and vertical ventilation in soybean heap is not significant difference.Through the transverse ventilation experiment of paddy heap in flat warehouse, we find that airflow distribution in the middle part of the grain is not uniform. The air flow through the bottom of the grain heap is small, while the air flow through the upper of the grain heap is big. The route of air flow through the grain heap like arch bridge. There exist problems such as poor cooling effect at the bottom of grain heap, large temperature difference between two sides of flat warehouse, it is bad for the safe storage of grain. Therefore, the effect of the application of horizontal ventilation in the warehouse is not up to the recommended effect.