Numerical Modeling and Analytical Validation for the Movement of Thermal Front in a Heterogeneous Aquifer Thermal Energy Storage System

The aquifer thermal energy storage system (ATES) owing to growing demands for sustainable energy has become a popular technology in last few decades for long term storing of excess thermal energy. The efficiency of such a system depends entirely on the capacity of the aquifer to retain heat and hence modeling the heat transfer and transient temperature distribution in the aquifer due to hot water injection is essential. The present study is concerned about presenting a two-dimensional numerical model for such an ATES system with block heterogeneities where hot water is injected through an injection well into the heterogeneous porous aquifer with lesser initial temperature. The transient temperature distribution in the porous aquifer or the advancement of the hot water thermal front generated due to hot water injection into the porous aquifer is modeled here using the multiphysics numerical code COMSOL. First the model is developed for the general case including the convective and the conductive heat transport. Since modeling of such complex systems are associated with numerical errors which may lead to possible errors in estimation of temperature distribution in the aquifer, the results derived numerically afterwards are compared and validated with an analytical model derived by the authors.