土壤原位热传导修复水-汽-热耦合输运模拟

Coupled water-vapor-heat transport simulation on in-situ thermal conduction heating remediation of soil

为了研究有机污染场地原位热传导热修复过程中地层温度的时空分布规律,基于典型场地建立水-汽-热耦合输运模型,通过COMSOL Multiphysics多物理场仿真平台对原位热传导修复过程中的土壤温升进行数值模拟研究,预测得到温度、水相及蒸汽相浓度分布随时间的变化规律.利用文献中的单根加热棒加热场地实测数据对模拟结果进行对比验证,通过参数化分析探究土壤孔隙度、水饱和度及毛细作用力对土壤温度时空分布的影响.结果表明,大孔隙度和水高饱和度将导致土壤温升减慢,这是由于大量热量用于液态水蒸发过程.毛细管力会强化液态水输运,增大蒸发速率.

Numerical simulations were performed using COMSOL Multiphysics to analyze the temperature rise in soil during the course of thermal conduction heating(TCH) remediation based on a coupled water-vapor-heat transport model in order to analyze the underground temporal and spatial temperature distributions during in-situ TCH remediation of organic compound-contaminated soil. The transient variations of the distributions of temperature, and water and vapor concentrations were predicted. The numerical results were validated by comparing with the existing experimental data obtained with a single TCH tube from field tests. Then the effects of soil porosity, water saturation, and capillarity on the temporal and spatial temperature distributions were analyzed by parametric analysis. Results show that the temperature rise rate becomes slower with higher porosity and water saturation, because more heat is used for the evaporation of water. Capillary force contributes to water migration.Then the evaporation rate is increased.