Induction ratio of active chilled beams - Measurement methods and influencing parameters

Journal article, 2016

In active chilled beams, primary air from the air handling unit induces room air which passes a cooling coil before it mixes with the primary air and discharges into the room. The ratio of induced room air flow to the primary air flow is the induction ratio (IR). Knowledge about the IR is important when modelling cooling capacity as well as temperature and velocity of the air discharged from the beam. Most previous studies of the behavior of IR are focusing on the influence of primary air flow. The purpose of the work presented in this paper is to investigate whether other operating conditions also influence the IR. Three methods of determining the IR are compared in order to strengthen the conclusions. The results indicate that the IR is influenced by the chilled water temperature due to buoyant forces. Novel methods of determining the IR are presented and it is concluded that current methods may lead to overestimation.