Monitoring heat transfer from a groundwater heat exchanger in a large tank model

A large tank (4x8x1.4 m), equipped with 26 standard piezometers and six temperature loggers with four channels each installed at different depth, is used to carry out thermal monitoring test and investigate environmental impact of heat borehole exchange. Loamy sediments (35 m3), used to fill the tank, were excavated from an unconfined alluvial aquifer near Ferrara (Northern Italy). To evaluate spatial heterogeneity, the tank’s filling material was characterized via slug tests and grain size distribution analysis. Constant heat input rate test was conducted by originating a heat plume using a groundwater heat exchanger (GHE). Temperature was monitored in continuous via data loggers. The effect of heat borehole exchange was small compared with the temperature applied. Results show a heat flux dominated by temperature gradient and thermal conduction. The effect of hydraulic conductivity heterogeneity on heat plume development is discussed. Tank model presented in this research looks to be suitable for heat transport modeling. Recommendations for future development of the research and future groundwater and heat transport modeling are also reported.