Comparison of the Performance of Chilled Beam with Swirl Jet and Diffuse Ceiling Air Supply: Impact of Heat Load Distribution

The impact of heat load strength and positioning on the indoor environment generated by diffuse ceiling air supply and chilled beam with radial swirl jet was studied and compared. An office room with two persons and a meeting room with six persons were simulated in a test room (4.5 x 3.95 x 3.5 m3 (L x W x H)).

A window (6.5 m2) was simulated by radiant panels. Four chilled beam units were installed symmetrically on the suspended ceiling together with two exhaust vents. The diffuse ceiling inlet was made of standard perforated acoustic tiles (0.5% total degree of perforation). The room air temperature was controlled at 24 °C.

The quality of the generated indoor environment as defined in ISO standard 7730 (2005) was assessed based on comprehensive physical measurements. The systems created Category A thermal environment in cooling situations at heat load of 50 W∙m−2 and 78 W∙m−2 (office room) and Category B thermal environment in the meeting room at high heat load of 94 W∙m−2.

The air distribution pattern was influenced by the convective flows from the heat sources. The maximum local velocity in the occupied zone was 0.23–0.26 m∙s−1. The diffuse ceiling supply did not ensure complete mixing (ventilation effectiveness of 0.4) and the air flow rate had to be above minimum to safeguard the indoor air quality.

The radial swirl jet of chilled beam also was not capable of creating complete mixing at high and concentrated heat load (ventilation effectiveness of 0.7).