Hydrogeothermal characterization and modelling of a standing column well experimental installation

Abstract

Standing column wells (SCW) are efficient ground heat exchangers that offer promising potential for integration in dense urban areas. Recent years have witnessed a growing interest in SCWs, resulting in the development of various simulation models incorporating heat transfer, groundwater flow and geochemical reactions within the well and the surrounding ground. However, these models commonly use a configuration that involves pumping at the bottom of the well and reinjection from its top, which can lead to installation and maintenance difficulties in deep wells. Furthermore, very few SCW models have been validated against reliable field data. This paper presents an original finite element model coupling advection-diffusion of heat and groundwater flow within a top pumped SCW and its surrounding ground as well as the experimental setup used for its validation. Within the scope of this study, experimental data obtained after an extensive field characterization campaign and a thermal response test performed with a large-scale geothermal laboratory were used directly as inputs in the numerical model. Experimental validation shows that without any calibration procedure, the model reproduces the experimental inlet and outlet groundwater temperatures with a mean absolute error of 0.14 °C. It is also shown that the placement of the pump at the top of the well offers a more practical design that has minor impact on the thermal performance of the system.