Numerical investigation of geometry parameters for designing efficient terminal units in active chilled beam

In this paper, we firstly present the principle of airflow in a terminal unit of active chilled beam (ACB) and airflow pattern in the secondary plenum. Taking the advantage of the computational fluid dynamics (CFD) techniques, we investigate the influences of geometry of the terminal unit on entrainment ratio (ER), which is the key parameter to measure the efficiency of a terminal unit. A graphical model for analysis in CFD is established in ANSYS software package to study the effect of two key paremeters, radius of nozzles and distance between nozzles on ER. After simulation, regression analysis is applied to the results to achieve a mathematical representation of the effect of radius of nozzles and distance between nozzles. It is found that the radius of nozzle is negatively correlated to ER, while the distance between nozzles is positively correlated to ER. The radius of nozzle has a stronger effect on ER than distance of nozzles.