MASS TRANSFER REACTIONS BETWEEN VOCS, AQUEOUS & VAPOR PHASES IN THE SUBSURFACE

挥发性有机化学品通常释放到环境中 非水相液体(NAPL)通过表面溢出、储罐 危险废物填埋场的渗漏或淋失。在场和 NAPL在地下系统中的行为尚未得到充分的解释 用于先前的含水层建模工作。这是两个同伴中的一个 密歇根大学将开展的项目以解决这一问题 缺乏症。该项目将专门关注 从有机液体到水相和气相的化学品。 将进行实验，以研究VOC从 剩余饱和度下填充塔中不相容有机液体 多孔介质。液-液和液-汽相转移 过程将用适当的传质来描述 系数和驱动力。特征之间的相关性 多孔介质(例如，粒度分布)和传质 将建立系数。流量、构型的变化 不相容相、初始润湿流体和柱长 允许对传质速率进行量化。一种广义的 描述传质和传质动力学的数学模型 通过多孔介质将被写成辅助分析 从这些实验中获得的数据。该模型将包括一个质量 非水液相平衡。局部均衡分配 和动力学传质表达式将作为选项纳入 描述相间质量交换的模型。从当地出发的航班 平衡将使用几种唯象传质来建模 与不混相性质有关的表达式和 多孔介质。根据这一分析，专门配置的质量 最接近于观测数据特征的传输模型将是 在计算机仿真器中确定并合并为“子模型” 在配套项目中正在开发。

Volatile organic chemicals are commonly released to the environment as non-aqueous phase liquids(NAPL) via surface spillage, storage tank leakage, or leaching from hazardous waste landfills. The presence and behavior of NAPL in subsurface systems has not been adequately accounted for in prior aquifer modeling efforts. This is one of two companion projects to be conducted at the University of Michigan to address that deficiency. This project will focus specifically on the mass transfer of chemicals from organic liquid phases to aqueous and vapor phases. Experiments will be conducted to examine VOC mass transfer from immiscible organic liquids at residual saturation in packed columns of porous media. Liquid-liquid and liquid-vapor interphase transfer processes will be described in terms of appropriate mass transfer coefficients and driving forces. Correlations between the characteristics of the porous media (e.g., grain size distribution) and the mass transfer coefficient will be established. Variations in flow rate, configuration of the immiscible phase, initial wetting fluid, and column length will permit quantification of rates of mass transfer. A generalized mathematical model describing the kinetics of mass transfer and transport through the porous media will be written to aid in the analysis of the data obtained from these experiments. The model will include a mass balance for the non-aqueous liquid phase. Local equilibrium partitioning and kinetic mass transfer expressions will be incorporated as options in the model to describe the interphase mass exchange. Departures from local equilibrium will be modeled using several phenomenological mass transfer expressions related to the properties of the immiscible phase and the porous media. Based on this analysis, that specifically configured mass transfer model which most closely characterizes the observed data will be identified and incorporated as a "sub-model" in the computer simulator being developed in the companion project.