Cooling effect of dynamic airflow with coordinated supply air velocity and temperature

Ventilation with dynamic supply air velocity intensifies stimulation of the skin cold receptors, thereby generating the cooling effect of dynamic airflow for the energy-efficient provision of thermal comfort. However, the maximum air velocity is constrained by thermal comfort standards, limiting the variation amplitude of the air velocity, thereby limiting the cooling effect of dynamic airflow. This study proposes a novel ventilation method with a coordinated dynamic supply air velocity and temperature, which matches the low air temperature with the high air velocity and matches the high air temperature with the low air velocity to equivalently extend the variation amplitude of the air velocity for enhanced cooling effect of dynamic airflow. The results of coupling the dynamic airflow field from the CFD simulation, JOS-3 human thermoregulation model, and Fiala dynamic thermal sensation model show that the cooling effect of dynamic airflow under the proposed dynamic air supply increases with an increasing amplitude variation in the supply air, but non-monotonically varies with an increasing frequency variation in the supply air. Additionally, the largest cooling effect is exhibited by the rectangular wave variation pattern, followed by the sinusoidal and triangular waves. The driving mechanism for thermoregulation, which produces an enhanced cooling effect through dynamic airflow, is also revealed. Compared to the steady air supply strategy, the cooling effects of the dynamic airflow generated using the existing and proposed dynamic air supply strategies reduce the thermal sensation by 0.33 scale and 0.63 scale, respectively, and save energy by 15 % and 22 %, respectively.