This paper proposes a 3-D convection-heat dispersion model for a confined aquifer. The governing equation of the model contains not only the traditional convection and conduction terms, but also a heat dispersion term which has often been overlooked in many similar researches. The model is used to describe a series of aquifer thermal energy storage experiments conducted at the Shanghai experimental site, including single-well injection, double-well injection/production and multiple-well injection/prodution tests. The simulated temperatures agree very well with the field data (relative error: 2.8%-4.5%). A detailed description of the model is given, followed by a detailed comparison of simulated and measured temperature distributions.