Computer simulation of ground-coupled liquid desiccant air conditioner for sub-tropical regions

Computer model for a novel ground-coupled liquid desiccant air conditioner (GCLDAC) was developed in which a liquid desiccant cycle selectively operated in parallel with a conventional ground-source heat pump cycle by employing just a single compressor. Reverse cycle operation was incorporated to provide heating in winter. Dynamic simulation was carried out for a single-zone sample building at two occupancy levels based on the weather data for Hong Kong and compared with those obtained using a conventional ground-source heat pump system (GSHP). It was found that the borehole length for GCLDAC was reduced by 10.1% on average under different groundwater velocities at a low occupancy level corresponding to a fresh air ratio of 0.066. A larger average reduction of 14.3% could be reached for a higher occupancy level corresponding to a fresh air ratio of 0.122. The energy consumptions for both systems were very close even when the additional parasitic energy consumption for GCLDAC was accounted for. A simple economic analysis indicated that if the borehole installation cost exceeded USD35.0/m, cost saving could be found for the new system at both occupancy levels. Should GCLDAC be manufactured in a low-cost region like China, the economic benefit could be furthered enhanced.