Temperature-dependent dissolution of residual non-aqueous phase liquids: model development and verification

The use of heat storages in the subsurface, especially in urbanized areas, may conflict with existing subsurface contaminations of non-aqueous phase liquids (NAPL). In this work, available data and models regarding temperature influences on parameters for kinetic NAPL dissolution of trichloroethene (TCE) are summarized, discussed and implemented into a numerical simulator. As systematic data on temperature-dependent TCE solubility, diffusion coefficients and dissolution rates are sparse, a set of high-resolution quasi-2D laboratory NAPL dissolution experiments using TCE was conducted at 10, 20, 40 and 70 degrees C. Because the experimental data show incomplete dissolution of the residual TCE-NAPL, two different classes of TCE-NAPL blobs representing fast and slow dissolution kinetics were introduced in the model. A good agreement of model simulations and experimental measurements of TCE mass flow rates could thus be obtained for each temperature investigated. The numerical model thus can be applied to simulate kinetic dissolution of residual NAPL source zones in groundwater under variable temperature conditions.