温度梯度下土壤盐分迁移过程的数值模拟  

NUMERICAL SIMULATION OF SALT MIGRATION IN SOIL UNDER DIFFERENT TEMPERATURE GRADIENTS

作　　者：王华军[1,2] 路俊超 杨宾[1] 齐承英[1] 

机构地区：[1]河北工业大学能源与环境工程学院,天津300401 [2]天津大学中低温热能高效利用教育部重点实验室,天津300072

出　　处：《太阳能学报》2014年第6期1086-1091,共6页Acta Energiae Solaris Sinica

基　　金：国家自然科学基金(50906020);中低温热能高效利用教育重点实验室开放基金(201301-101)

摘　　要：初步建立温度梯度下非饱和土壤水-汽-盐迁移过程的数学模型,并进行数值求解。结果表明,随着加热时间延长,土壤盐分浓度会在热端附近出现明显聚集,甚至超出饱和浓度而发生结晶析出,而冷端土壤的水-汽-盐耦合现象并不明显,其中温度场变化可以忽略,盐分浓度因水分迁移而略微下降。随着冷热端温度梯度的增加,土壤盐分向冷端扩散的距离越远,且由于浓度逐渐被沿程稀释,盐分出现结晶的区间宽度呈减小趋势。随着土壤初始盐分浓度增加,上述的盐分聚集现象呈增强趋势。当土壤初始含水量接近饱和或干燥状态时,盐分浓度场变化相对较弱,而当非饱和土壤中水蒸气扩散强烈时,土壤盐分浓度场变化十分剧烈。A preliminary theoretical model to describe the water-vapor-salt diffusion in variable-saturated soil under different temperature gradients was established and solved numerically. The simulation results show that the salt concentration increases obviously near the heat end as the heating time increases, and even exceeding the saturation, the salt precipitation may appear. By contrast, the water-vapor-salt diffusion near the cold end is weaker, where the variation of the temperature field can be neglected and the salt concentration decreases slightly. As the temperature gradient increases, the salt diffusion tends to be far away from the heat end and the width of the salt precipitation region decreases due to the dilution effect. The salt accumulation effect is enhanced greatly as the initial salt concentration increases. The salt concentration changes weakly when the initial moisture content in soil is close to a dry or saturated condition, but drastically when the enhanced vapor diffusion is dominated in the unsaturated soil.

关 键 词：土壤 温度梯度 盐分迁移 水蒸气扩散 

分 类 号：TK124[动力工程及工程热物理—工程热物理]