Airflow Characteristics of Stratum Ventilation

This chapter investigates the airflow characteristics of stratum ventilation by compared with two existing methods, i.e., mixing ventilation and displacement ventilation. This chapter measures the air velocity and temperature within the occupied zone of a classroom with multiple occupants under cooling mode. Based on the measured data, the turbulence intensity and the power spectrum of velocity fluctuations are evaluated. Additionally, thermal comfort and cooling efficiency are also evaluated. The results highlight distinct airflow behaviors among stratum ventilation, mixing ventilation, and displacement ventilation. The presence of multiple thermal manikins in the classroom exacerbates turbulent airflow fluctuations due to the mixing effects of the thermal buoyancy and supply airflow. Compared with mixing ventilation and displacement ventilation, stratum ventilation requires a higher supply air temperature for overall comfort while minimizing draft risks. Analysis of mean air temperatures in the occupied zone demonstrates that stratum ventilation exhibits the highest cooling efficiency, followed by displacement ventilation and mixing ventilation, respectively.