Adoption of flat panels in soil heat exchange

Ground heat exchangers (GHEs) are rarely installed horizontally in linked ground source heat pumps used for space conditioning, because the horizontal installation energetic performance is lower than the vertical one. However, the horizontal installation holds several advantages: it is easy to carry out and upkeep, it is more compliant with environmental regulations, and interferes marginally with groundwater systems. To keep these desirable features and improve the energetic performance, we examine a novel geometry for horizontal GHEs, consisting of a flat panel installed vertically at shallow depth below the water table, and coupled with a linked heat pump for heating and cooling. A numerical finite element model is used for resolving the flow and thermal fields in transient conditions, determining the soil temperature distribution. The resulting energetic performance of the flat panel is almost four times higher than that of a regular horizontal exchanger.