横向谷冷通风过程的数值模拟研究

基于局部热湿平衡原理和多孔介质传热传质理论,建立了储粮通风过程中粮堆内部流动及热湿耦合传递的数学模型。采用计算流体动力学的方法,对横向谷冷通风时粮堆空气内部流动、热量传递和水分迁移过程进行了数值分析。研究发现,横向通风约72 h,粮仓进风口冷空气平均温度为17.5℃、相对湿度为85%,仓内粮堆一次降温从32.2℃降低到23.6℃,降温幅度为8.6℃。水分从12.2%降到12.0%,降水幅度为0.2%。相对于地上笼垂直通风而言,横向通风时粮堆内部速度分布均匀、温度梯度较小,且具有降温速度快,冷却效率高的特点。

Numerical Study on Heat and Moisture Transfer in Stored Grains during the Horizontal Aeration with Cooling Air

In the this paper, a mathematical model based on the principle of local thermal equilibrium and theory of heat and mass transfer in porous media was developed to simulate the evolution of temperature and moisture content of stored wheat in a warehouse during the horizontal aeration with cooling air at the constant temperature and humidity. Validation was performed by comparing between simulated and measured temperature and moisture content of stored wheat in Qingyuan Grain-depot. In the simulation, bulk wheat placed in store at 12.2% w.b. moisture content and 32.2 °C was cooled and dried to 23.2 °C and 12.0% w.b. moisture content in three days during the horizontal aeration with cooling air at 17.5 °C and 85% relative humidity. It is shown that the simulated data were in reasonable good agreement with measured ones, temperature gradient in stored wheat is minimal, and cooling effect on stored wheat is significant during the horizontal aeration with cooling air.