An experimental and numerical study on the effect of air terminal types on the performance of stratum ventilation

The purpose of this paper is to investigate the effect of air terminal types on the design and performance of stratum ventilation. Four types of air terminals, including circular diffusers, square diffusers, perforated diffusers and double deflection grilles were studied by experimental and numerical methods. Human subject tests of thermal sensations and comfort were conducted under various experimental conditions. The performance of stratum ventilation was evaluated by six indicators: airflow pattern, temperature distribution, air diffusion performance index, thermal sensation and comfort feedback, local mean age of air and CO2 concentration. The results indicate that air terminal type has a significant effect on airflow pattern. Good air diffusion performances were achieved with four types of diffusers. More than 80% subjects felt thermally comfortable with circular and perforated diffusers. In terms of air quality, the local mean age of air for the circular diffuser case was the oldest, while the CO2 concentration in the breathing zone was the second lowest and the most uniform for this case. Thus, the circular diffuser can be a better choice for stratum ventilation.