Simplified model for thermal comfort, IAQ and energy savings in rooms conditioned by displacement ventilation aided with transient personalized ventilation

The aim of this work is to evaluate the performance of an intermittent personalized ventilation (PV) system assisting a displacement ventilation (DV) system based on its ability in improving thermal comfort and protecting occupants from floor emitted passive contaminants. A simplified transient mathematical model was developed of heat and species transport to predict the temperature and concentration fields in the macroclimate room air, in the thermal plume induced by the occupant and internal heat sources and within the intermittent PV jet facing the occupant face at a fixed distance. The model's predictions of temperature and concentration were experimentally validated for a PV frequency range [0.3-1 Hz] in a climatic chamber conditioned with a DV system assisted with an intermittent PV jet. Good agreement was found between the predicted and measured values of temperature and concentration of tracer gas in the different regions of macroclimate air, thermal plume, and PV jet. The validated model was used to conduct a case study where comfort and air quality were assessed and the energy consumption of the transient PV + DV system was compared to steady PV + DV and standalone DV systems. It was found that the intermittent PV range [0.3-1 Hz] was able to improve comfort compared to steady PV and provide acceptable air quality. Moreover, energy analysis showed that the intermittent PV + DV (40 L/s) was able to achieve maximum energy savings of 54.61% and 31.58% compared to a standalone DV and steady PV respectively for equivalent comfort.