不同仓型的粮堆温度场重现及对比分析

为了揭示不同仓型粮堆内温度场和水气分压场随季节的变化规律及其对储粮安全的影响,该文以天津地区的钢板浅圆仓和平房仓为研究对象,以小麦为储粮目标,采用阵列式分布的温度传感器监测粮堆温度,利用温度拟合算法和WU模型构建粮堆温度场模型,重现粮堆在冬末春初之际和夏季的温度场和水气分压场分布;根据温湿度场耦合理论分析其云图特征,并在此基础上比较2种仓储粮状态的差异。结果表明:夏季,浅圆仓和平房仓的小麦粮堆中均存在大体积的冷芯,使整个粮堆可以安全度夏;冬春交替之际,2种仓的粮堆中均存在多区域分层现象,但由于浅圆仓的表层粮堆水分吸收速率大于平房仓,致使次年春季浅圆仓的粮堆表层更易发生结露;根据平房仓小麦粮堆的等温曲线变化方向可推测有邻仓存在,且由2个毗邻的平房仓温度场融汇度可判定邻仓有储粮。研究结果将为粮堆结露研究提供新思路,为结露预测提供理论依据。

Comparison and analysis of temperature field reappearance in stored grain of different warehouses

Abstract: Grain storage has very important effects on national security and has been given increasing attentions at past several decades. Condensation is one of the main dangers to the grain storage safety. Temperature, moisture and warehouse type are the three most important factors to form condensation. However, it is very difficult to study the effects of temperature and moisture on the grain storage safety in the actual granary due to the huge cost. So, it is a good choice by building models to forecast the changes of temperature or humidity in the granary by experiments. At present, the studies were still at the middle-small experimental stages in the domestic and overseas. Due to the differences of climate, long storage period and warehouse types at different regions, it is more difficult to build the universal temperature or humidity models in China than other nations.To explore the condensation processes, wheat were storage in steel squat silo and horizontal bin located in Tianjin District respectively, which were used widely to store grain in China. The changes of temperature and water vapor pressure of the wheat in spring, summer and winter were researched in the paper. The grain temperature data in different seasons was obtained by sensors array. Second Newton interpolation method was used to obtain the fitting algorithm of temperature. The data of wheat water vapor pressure was figured out by WU model. The temperature fields and the water vapor pressure field of the wheat in two researched storehouse were reproduced by MATLAB software, respectively. Then, the cloud maps were analyzed according to the coupling principle of temperature and water vapor pressure fields and WU model.The results showed that a large cold area existed in the wheat in the steel squat silo or the horizontal bin in summer, which could be the main reason of non-dewfall and resulted in a storage safety. A multi-level water vapor pressure zone, which was defined as the low-water vapor pressure area and high-ones alternately appeared in the stored wheat, all was observed in the wheat in the steel squat silo and the horizontal bin during late winter to early spring. More significant multi-level water vapor pressure zone (which suggested a larger gradient of grain temperature and water vapor pressure) and more moisture absorbed rate of the surface grain than that of the horizontal bin resulted in the condensation on the surface occurred more easily in the steel squat silo in early spring, which suggested a storage risk of the wheat in spring. The isotherm was different remarkably between the two warehouses. In the steel squat silo, the isotherm was closed, but it presented non-closed in the horizontal bin. Based on the change direction of isothermal curve, it could deduce that there was another horizontal bin bordered. Additionally, the isotherms of the two horizontal bins could close well from the temperature field cloud maps, which suggested grain stored in the bordered horizontal bin. The results were in consistent with the actual. They provided not only new thought of forecasting condensation, but also new perspective of making inventories of warehouses.