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Scale-model Study of Airflow Characteristics in Non-isothermal Ceiling Slot-ventilated Enclosures

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  Paper number  024107,  2002 ASAE Annual Meeting . (doi: 10.13031/2013.11693) @2002
Authors:   Hsin Yu
Keywords:   Airflow characteristics, Slot-ventilated, Ventilation, Non-isothermal

Airflow characteristics in non-isothermal condition are more close to the real phenomenon than in isothermal condition. Air-jet issued from ceiling slot is a two-dimensional plane wall jet which affects room environmental quality. Scale-model study of a non-isothermal ceiling slotventilated enclosure was investigated in both airspeed field and thermal field. Results of airflow pattern, centerline velocity decay, centerline temperature decay, airflow boundary layer growth, thermal boundary layer growth, velocity profile, and temperature profile were regressed or analyzed to establish semi-empirical prediction equation. The results also compared with previous research to validate the physical behavior of air-jet. Data of centerline velocity decay showed similar airflow characteristics as isothermal air-jet with Ar < 0.004, which performed as pseudo-isothermal airflow. The centerline temperature decay was regressed well as the form of Li et al.s (1993) results. Airflow boundary layer growth was agreed better with Rajaratnams (1976) conclusion and the thermal boundary layer growth was fit both Albright and Scott (1974) and Wilson et al.s (1970) results. Both the velocity profile and temperature profile agreed with the results of literatures. Analysis of airflow performance in non-isothermal condition make progress in predicting air quality inside the enclosures and guide the design concepts of ventilation system in animal houses.

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