Development of a heat exchange unit and a potential map for shallow groundwater thermal energy

Abstract

A geothermal exchange unit has been developed to reduce the capital costs of ground source heat pump systems. Its source of heat energy is shallow groundwater. The geothermal exchange unit comprises flexible containers, sheets of heat exchanger and gravel of high permeability. The sheets of heat exchanger run helically through flexible containers in the unit with gravel. Demonstration experiments in the Kurobe alluvial fan proved that the unit can be installed up to GL-3 m by excavating with heavy equipment. The result of demonstration experiments showed that the average and the standard deviation of cooling outputs are 3.1 and 0.8 kW, respectively. Furthermore, this study selected a candidate area for unit installation based on the depth limit of excavation with heavy equipment and the water table. In result, this study proved that the unit can be installed in the fan toe with water table and high Darcy velocity.