Modeling Approaches Applied to the Thermal Response Test: A Critical Review of the Literature

This article provides a comparative review of various modeling approaches adopted in the open literature dealing with the parameter estimation procedure required in the geothermal thermal response test (TRT). First, the set of partial differential equations is introduced that describes the combined convective–conductive phenomena occurring in a borehole and in the energy storage system represented by the surrounding soil. The various approaches given in the literature for formulating approximate models are then illustrated. A model-based classification is adopted while introducing and reviewing the analytical and numerical methods found in the literature, including one-, two-, and three-dimensional approaches available for processing the experimental data resulting from the TRT. The various modeling procedures that have been applied to the TRT are discussed and compared to point out their strengths and weaknesses in relation to their differing extraction of information from the input data, represented by the time history of the experimental fluid temperature.