| Summary: | 碩士 === 國立臺灣科技大學 === 建築系 === 94 === Buoyancy ventilation in atrium is very important in architectural physical environment design. Architects and the technical staff need to find the resolutions cooperatively. The measurement of volume flow rate and the position of the interface are both key points to consider. In terms of volume flow rate, the thermal environment of atrium influences health and comfort of the occupants in the building. Therefore, it needs to adopt economic and reasonable methods for ventilation in order to eliminate the cooling and heating load, and dilute the concentration of harmful gases, and particles. Besides, in terms of the position of interface height, inappropriate design would cause outdoor hot air backward through high position openings into the building. It seriously affects the thermal environment of the upper room in high-rise buildings. The study attempted to investigate the volume flow rate of buoyancy ventilation in atrium and the difference in interface heights. The research adopted the method of CFD computer simulation with the theoretical of formula forecast. Then, the researcher provided some suggestions on designing principles.
The result showed that the height of atrium was elevated without wind, the air flow rate increased and the height of interface decreased. The height of opening was raised each 3m, the airflow rate increased 220m³/hr. In addition, the interface heights of simulation were higher than the interface heights of theoretical formula. Enlarging the opening area 4 times causes 2.65 times air flow rate. In addition, when the analysis of simulation was close to the formula forecast, the outlet was larger.
The point of heat source, the same as the bibliography, showed the obvious stratification between heating and cooling. However, the uniform heat source did not have strong stratification and elevate the position of interface height when the uniform heat source moves above. On the contrary, while with wind fields, the angle position of the opening and the position of inlet in atrium under the negative pressure of windward. Then, the velocity of wind outdoors was smaller than 1.5~2m/s. Due to the inlet pressure was smaller than outlet pressure; the opposite route of stack ventilation, cross ventilation, was produced. Therefore, it eliminated the effects of the stack ventilation indoors. However, the velocity of wind outdoors was achieved to 2m/s, and the cross ventilation was larger than stack ventilation. Then, the ventilation path was controlled by the cross ventilation.
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