Research Of Temperature Change Regularity Of The Stored Grain In Warehouse

At present, national grain storage depot mainly use warehouse to store grain. The warehouse has large storage capacity, it can be up to 60m in length and 25-30m in width. The grain bulk can be up to 6m high in warehouse. The warehouses have excellent insulation and moisture proof performance. They have system of grain temperature detection, system of mechanical ventilation, etc., which provide reliable security in grain storage. Due to the enormous volume of stored grain in the warehouse and slow heat transfer speed of grain, the internal grain is wrapped and efficiently protected by external grain. But at the same time, in summer, because of the cumulative heat transfer from the hot air, the large area of external grain's temperature is increasing, it results in the phenomenon of "hot shell and cold center", makes the external grain temperature much higher, even up to the suitable temperature for some pests to grow and reproduce. It can easily results in the spread of some pests, and makes the internal part of grain bulk becoming warmer, which causes harm to the safety of grain storage.Additionally, when people analyze the temperature changes of grain bulk, they only consider the solid heat transfer of the grain bulk, neglecting of the effects of micro-airflow in the grain bulk. This results in an insufficient estimation for the capacity of heat transfer in grain bulk. Also, in summer and winter, because of the large difference between warehouse temperature and the grain temperature, it can easily cause the phenomenon of regular micro-airflow in the internal grain bulk, which can cause the temperature change in the grain bulk to be more complex.According to these cases, this paper mainly researches the temperature change regularity of the internal grain bulk and the external influence. The main works of the research are as below:(1) Firstly, collect the temperature of grain in warehouses named 10A and 6A of Central Grain Reserves Changchun, convert the collected binary temperature data to decimal data, then set up the temperature model of warehouses.(2) Simulate the process of heat transfer of grain by three-dimensional heat conduction equation, then solve the heat conduction equation by LOD finite-difference scheme, to identify the influence of micro-airflow inside the grain bulk.(3) Use the heat conduction equation to explain the phenomenon of "hot shell and cold center" in the warehouse at summer, analyze the influence of the warehouse temperature to the top of grain bulk, the influence of ground temperature to the bottom of grain bulk, and the influence of walls to the side part of grain bulk.