Performance evaluation and design guide for a coupled displacement-ventilation and passive-chilled-beam system

Displacement ventilation (DV) can provide good air quality to indoor spaces while saving energy. Research has shown that, since the supply air temperature in DV cannot be very low, its capability to remove a high cooling load is limited. Previous studies found that passive chilled beams (PCBs) could be coupled with DV to enhance the cooling capability of the latter and reduce the vertical temperature gradient. However, PCBs also recirculate airborne contaminants downward, reducing the air quality in the occupied zone. Therefore, it is essential to design a DV-PCB system for optimal thermal comfort and indoor air quality. This study established a database of 70 cases that include four typical types of indoor spaces with DV-PCB systems and developed mathematical models for predicting the thermal and ventilation performance of a DV-PCB system based on various design parameters. With the models, this investigation then proposed a step-by-step procedure for designing a DV-PCB system to create a thermally comfortable and healthy indoor environment without causing condensation on the chilled beams. Moreover, a user-friendly design interface was developed that can be used by engineers to make design decisions conveniently.