Fresh air personalized ventilator systems for occupant-controlled microenvironment

Abstract

The project aims towards integrating more than one air distribution system by separating the fresh and recirculation air supply system in an effort to lower fresh air needs and to substantially reduce the air conditioning system energy consumption. The study investigated two different scenarios for the integration of the personalized ventilation (PV) systems: Displacement ventilation systems (DV) assisted by desk-mounted PV modules, and ceiling-mounted PV nozzles with an innovative air delivery system. A simplified numerical model was developed to assess the importance of the PV systems in improving the IAQ and reducing the energy consumption of the DV systems. The particularity of this model is that it allows for different zone temperatures within an air layer in contrary to the homogeneous air mixing that is considered in most of the literature models. The improved predictive model was validated experimentally and then applied to practical cases in order to assess the energy saving potential and associated thermal comfort. On the other hand, an innovative air delivery system consisting of a coaxial nozzle and angled return air was proposed and was not only used for the effective supply of fresh air to the occupant’s breathing zone (as it is the case with most of literature studies) but also to localize the conditioned air to the immediate surroundings of the occupant via the angled flow of the return diffuser. The air delivery design provided the occupant with the opportunity to control his own microenvironment. This work is the first to investigate the effectiveness of the coaxial nozzle in delivering fresh air when mounted in the ceiling and is also the first to consider the use of such integrated air delivery system for localizing the occupant’s needs for air conditioned environment in an open space and for allowing the occupant to control his own microenvironment. The performance of this proposed air delivery system was investigated in terms of air quality, energy consumption and thermal comfo