Combination of ground source heat pumps with chemical dehumidification of air

In the present paper the possible synergies provided by the combination of an underground thermal energy storage (UTES) system with a desiccant based air handling unit (AHU) are analysed. Differently from the conventional solutions, the summer humidity control is obtained here by chemical dehumidification of the ventilation airstream performed by liquid desiccants in a packed column. Being the water temperature of the boreholes heat exchangers generally suitable to meet the sensible load without any integration with the chillers, the plant can operate in a complete free-cooling mode. In winter, the main benefits are due to the higher temperature level at which the UTES works and to the AHU configuration allowing sensible and latent heat recovery. For the same reasons, the required UTES size is sensibly smaller, reducing in this way not only the operation but above all the investment costs. The UTES system competitiveness is then increased. The described solution is investigated by a computer simulation referring to a modern office building in the climate of northern Italy and its performance has been compared to a traditional HVAC plant and to a traditional ground source heat pump (GSHP) system. Finally, some economic evaluations are reported, showing the competitiveness of the proposed configuration.