Analysis of Air Diffusion Performance Index of Fixed Vane Air Supply Type Ventilation System by Real Space Experiment

This study examined the potential of using a ductless, fixed vane air supply type ventilation system as a solution to structural and cost limitations of duct-type systems in aging buildings. The performance of such ductless, fixed vane air supply type ventilation system was evaluated based on air delivery, indoor airflow distribution, and thermal comfort. Measurements showed a turbulence intensity of 4% at the diffuser outlet, with an average velocity of 2.69 m/s and a velocity standard deviation of 0.12 m/s, indicating a stable airflow. Airflow distribution results revealed velocities between 0.05 m/s and 0.3 m/s, providing a stable and imperceptible draft sensation for seated and standing occupants. The system maintained effective air delivery up to 8 m from the diffuser, achieving uniform air distribution throughout the space. Effective Draft Temperature (EDT) analysis confirmed that airflow and temperature variations remained within the ADPI comfort zone. These findings demonstrate that ductless, fixed vane air supply systems can effectively address limitations of ducted systems while ensuring thermal comfort. This study provides a practical framework for implementing cost-effective and efficient ventilation solutions in aging buildings.