GROUND HEAT TRANSFER FROM A DRAINAGE TRENCH

The energy performance of a shallow ground heat exchanger constituted by a drainage trench is studied. The 12 x 2 £ 0.5 m trench is dug in shallow soil and filled with gravel; two vertical tubes at the opposite ends of the trench act as inlet and outlet of the working fluid, which flows into the closed loop of a system for heating/cooling of a residential building. Groundwater flow and heat transfer in the porous domain surrounding the trench are analyzed via a 3D numerical model, performing a 3-year simulation. The thermal impact of the exchanger is analyzed considering different boundary conditions (first/second kind), given as daily time series at the ground surface. The trench shows a good specific energy production and a significant capacity of smoothing thermal waves, and can be considered a convenient alternative in shallow applications.