Effect of active chilled beam layouts on ventilation performance and thermal comfort under variable heat gain conditions

The active chilled beam system has been popularly used in office and meeting rooms. There are very few studies of their terminal configuration on the thermal comfort and ventilation performance of systems with different heat gains. A comparative experimental study was implemented in mock-up office and meeting rooms to provide a comprehensive evaluation of the airflow patterns, air distribution, ventilation effectiveness, and local thermal comfort of the 4-way system. Four different terminal layouts with two types of the chilled beams (600 unit and 1200 unit sized 0.6 m x 0.6 m and 1.2 m x 0.6 m, respectively) were tested at three heat gain levels: low (46W/ m2) and medium (66W/m2) heat gains in the office room, and high (92W/m2) heat gain in the meeting room. The results revealed that the terminal layouts and heat gain levels had significant effects on air distribution and local thermal comfort. The increased heat gains generated lower heat removal effectiveness, worse indoor thermal uniformity, and increased risk of draught. Generally, the 1200-unit system performed better than that with 600 units for heat removal effectiveness and contaminant removal effectiveness. In terms of local thermal comfort, the 600-unit system generally provided higher performance than that with the 1200-unit system. The practical recommendations for the system design and operation stages are provided based on the operating range of the 4-way systems under variable terminal layouts and heat gain conditions.