Application potential of solar air-conditioning systems for displacement ventilation

Solar air-conditioning can have higher application potential for buildings through the strategy of high temperature cooling. In recent years, displacement ventilation (DV), which makes use of the indoor rising plumes from the internal heat gains, provides a more effective supply air option than the traditional mixing ventilation (MV) in terms of both thermal comfort and indoor air quality. As it is possible to raise the supply air temperature to 19 °C for DV, it would enhance the competitive edge of the solar air-conditioning against the conventional vapour compression refrigeration. Through dynamic simulation, a solar-desiccant-cooling displacement ventilation system (SDC_DV) was developed for full-fresh-air provision, while a solar-hybrid-desiccant-cooling displacement ventilation system (SHDC_DV) for return air arrangement. The latter was further hybridized with absorption chiller (AB) to become SHDCAB_DV, or adsorption chiller (AD) to be SHDCAD_DV, in order to be wholly energized by the solar thermal gain. Benchmarked with the conventional system using MV, the SDC_DV had 43.3% saving in year-round primary energy consumption for a typical office in the subtropical climate; the SHDCAB_DV had 49.5% saving, and the SHDCAD_DV had 18.3% saving. Compared with their MV counterparts, the SDC_DV, the SHDCAB_DV and the SHDCAD_DV could have 42.4%, 21.9% and 30.3% saving respectively.

► Application potential of solar air-conditioning with displacement ventilation (DV) was assured. ► A solar-desiccant-cooling DV system was designed for full-fresh-air provision. ► A solar-hybrid-desiccant-cooling DV system was used for return air arrangement. ► Benchmarked with conventional system, SDC_DV had 43.3% primary energy saving. ► SHDCAB_DV and SHDCAD_DV could have 21.9% and 30.3% saving.