基于多尺度的稻谷干燥热湿耦合传递的数值研究

为保证稻谷在储藏时的品质，收获后的稻谷通常需要干燥到一定水分后储藏，研究稻谷干燥过程的热湿传递规律具有重要意义。目前稻谷干燥过程中热湿传递的分析大多基于连续介质假说和局部热湿平衡原理而进行的，这种方法的局限性在于很难获得粮堆干燥过程中粮粒内部的热湿迁移规律。本文基于稻谷粮堆孔隙尺度和粮粒尺度，采用局部非平衡热湿传递模型，模拟分析了在对流干燥条件下稻谷单颗粒以及颗粒群的热湿传递规律。研究结果表明，本研究模拟值与文献中干燥实验数据相对误差(RE)小于6.50 %，平均相对偏差(MRD)小于4.00 %，得出该模型具有一定的准确性；与基于局部热湿平衡多孔介质热湿耦合研究方法所得的稻谷颗粒群温度和水分传递结果进行对比，本研究所建立的模型更能准确体现出谷物颗粒在通风干燥时内部的热湿迁移规律。本研究所开发的模型能预测不同尺度下稻谷颗粒的温度和水分分布。

Numerical study on coupled heat and moisture transfer of rice drying based on multi-scale

In order to ensure the quality of rice during storage, the harvested rice usually needs to be dried to a certain amount of moisture before storage. It is of great significance to study the law of heat and moisture transfer during the drying process of rice. At present, most analysis of heat and moisture transfer in the drying process of rice are based on the continuum hypothesis and the principle of local heat and moisture balance. The limitation of this method is that it is difficult to obtain the law of heat and moisture transfer inside the grain during pile drying. In this study, based on the pore scale and grain scale of rice pile, a local non-equilibrium heat and moisture transfer model is used to simulate and analyze the heat and moisture transfer of single grain and grain group of rice under convective drying condition. The results show that the Relative Error (RE) and the Mean Relative Deviation (MRD) between the simulated values and the drying experimental data in the literature are less than 6.50 % and 4.00 %, indicating that the model has certain accuracy. Compared with the model based on local heat and moisture balance, the model established in this study can more accurately reflect the internal heat and moisture migration law of rice particles during ventilation and drying. The model developed in this study can predict the temperature and moisture distribution of rice grains at different scales.