Field monitoring of a HGHE Flat Panel

In this paper we describe an experimental setting devised to investigate the behaviour of a novel type of horizontal ground heat exchanger (HGHE), consisting of a flat panel positioned horizontally and edgeways at shallow depth. At the experimental site, two flat panel HGHE are coupled with an hydraulic closed loop in which warm/cool water is circulated to simulate cooling/heating mode. Seveny-seven digital thermal sensors are installed along eleven different lines to monitor the soil temperature distribution during a dynamic test. A 15-days measurement campaign was performed during the spring of 2011, allowing to reconstruct temperature profiles within the soil and estimate an energetic performance of 60-140 W/m. These results were validated by comparing the temperature profiles with an approximate analytical solution, and performing an energy balance. The latter yielded values of heat exchanged at the soil surface in the order of 7 W/m2, comparing favorably with literature results.