Scale model study of airflow performance in a ceiling slot-ventilated enclosure: Non-isothermal condition

Abstract

Scale-model study of a non-isothermal ceiling slot-ventilated enclosure was investigated in both airspeed and thermal fields. Results of airflow pattern, centerline velocity and centerline temperature decay, velocity and temperature profile, airflow boundary layer and thermal boundary layer growth, floor velocity, and floor temperature difference were analyzed to establish semi-empirical prediction equations. Results also compared with previous researches to validate the physical behavior of air-jet. Data of centerline velocity decay showed similar airflow characteristics as isothermal air-jet with Archimedes number ( Ar ) < 0.004 , which performed as pseudo-isothermal airflow. Air-jet fell on entry with Ar > 0.018 . A single circulation airflow existed at 0.004 < Ar < 0.011 and two-circulation airflow occurred at 0.011 < Ar < 0.018 . The centerline velocity decay was fitted well as similar form of an isothermal condition. The centerline temperature decay was fitted well as the form of centerline velocity decay in both ceiling and floor regions. Both the velocity and temperature profiles agreed with results obtained from literature. Both airflow boundary layer and thermal boundary layer growths increased with traveling distance of air-jet. Maximum floor velocity and floor temperature difference were fitted well with different parameters. Analysis of airflow performance in a non-isothermal condition makes progress in predicting air quality inside the enclosures and guides the design concepts of ventilation system for an indoor environment.