Effect of shifts from occupant design position on performance of ceiling personalized ventilation assisted with desk fan or chair fans

Abstract

Recently, personalized ventilation systems have gained popularity since they consist on localizing the occupant needs in terms of thermal comfort and indoor air quality (IAQ). Localized ventilation systems are designed on the basis of fixed occupant position. Since people move and do not remain in same position, it is of interest to study personalized ventilation system performance with respect to shifts from occupant design position. The aim of this work is to study and compare the performance of ceiling personalized ventilation (CPV) when aided with desk fans (DF) versus chair fans (CF) in crowded office spaces for shifts from seated occupant chair position with respect to the CPV jet. A computational fluid dynamics (CFD) model for particle transport and deposition was developed to simulate a two-station office ventilated by CPV system to predict particle transport and to assess ventilation effectiveness. The CFD model was coupled with a bio-heat model to predict segmental and overall sensation and comfort in addition to segmental skin temperatures. In this work, experiments were conducted to validate the CFD model accuracy in capturing the effect of the CF on particle transport. The use of CF allowed the reduction of CPV flow rate by 22.72% resulting in energy savings of 14.87% for the case where the occupant was beneath the jet. Installing CFs allowed maintaining good performance of the system when chair shift due to movement of person occurred while installing DFs resulted in largely degrading the system performance at equal chair shift from the CPV center. © 2016 Elsevier B.V. All rights reserved.