Chilled water temperature control of self-regulating active chilled beams

Abstract

The flow rate of chilled water in a self-regulating active chilled beam is constant without respect to the actual cooling load. The cooling capacity is instead determined by the room temperature, which gives rise to the selfregulating effect, and also by the centrally controlled chilled water temperature, which is the focus of this paper. Previous studies have emphasized the benefit of avoiding room-level control equipment, but also highlighted the risk of overcooling with detrimental effects on thermal climate and energy demand. Overcooling may be avoided by supply temperature control, but strategies have not yet been studied in systems operating in cooling mode only. Simulations are carried out with IDA ICE. The results show that overcooling is effectively avoided by proper control of the chilled water temperature. Desired thermal climate is achieved and the energy demand is in the same order of magnitude as in a system with individually and ideally PI-controlled active chilled beams.