Optimized performance of displacement ventilation aided with chair fans for comfort and indoor air quality

• The performance of displacement ventilation (DV) system aided with chair fans (CF) is optimized.
• A CFD model and bio-heat model were used in the simulations to assess comfort and air quality.
• The model was validated experimentally using a thermal manikin seated on a chair equipped with fans.
• Optimal fan height is between 30 and 31 cm above the floor at fan total flow rate of 12 m L/s.
• Compared to stand alone DV system without chair fans, energy savings ranged between 20.6% and 11.6%.

This study optimizes the performance of displacement ventilation (DV) system aided with chair fans (CF) for providing acceptable thermal comfort and indoor air quality (IAQ) in office space. A 3-D computational fluid dynamics (CFD) model coupled with a bio-heat model was used to predict the airflow, temperature, and CO2 concentrations fields as well as the occupant segmental skin temperatures for local and overall thermal sensation and comfort evaluation. The CFD model results were validated experimentally in a DV conditioned space using a thermal manikin seated on a chair equipped with fans.Simulations were performed using the validated CFD model to determine the fans optimal height from the floor. For a pollution source located at 1.0 m from the floor, it is recommended to place the fans at 30.9 cm above the floor at fans total flow rate of 12 L/s while for a pollution source located at 0.3 m from the floor, the optimal height of fans is at 30.1 cm above the floor at fans total flow rate of 12 L/s. Compared to stand alone DV system, energy savings were 20.6% and 11.6% for fans’ optimal heights of the sources placed at 1.0 m and 0.3 m, respectively.