| Summary: | 碩士 === 國立臺灣科技大學 === 機械工程系 === 103 === The purpose of this research is to study the extraction mechani-
cal displacement ventilation and investigate the effects of the supply
source and the extraction sink on mechanical displacement ventila-
tion. The salt-bath technique is employed to conduct the experi-
ments by using the acrylic reduced-scale model. A partition with an
opening was placed in the middle of the acrylic reduced-scale model
to divide the model into two individual chambers. According to
the partition opening area, the experimental are categorized as two
series, Ex(I) and Ex(II). The partition opening area of Ex(I) and
Ex(II) is and 51 cm2 respectively. Each series includes four differ-
ent extraction flow rate, Qex = 1,2,3 and 4 LPM. The density plume
as a buoyancy source is placed on the top of the forced room and
extraction device is installed on the bottom of the forced room. The
environmental fluid flow throw in the opening on the top of the un-
forced room. Experimental results show that as the extraction flow
rate increases, the distance from the plume source to the interface
height increases; and the density of the buoyancy layer decreases.
The stratification stability highly depends on the inflow momentum.
The smaller partition opening area induces the larger inflow momen-
tum, such as Ex(I) series of experiments. The mixed layer of Ex(I)
is more noticeable than that of Ex(II) for a give extraction flow rate.
Comparisons between extraction mechanical displacement ventila-
tion and supply mechanical displacement ventilation show that the
intensity contour of the supply mechanical displacement ventilation
is almost horizontal and that means the intensity is the same at the same level. The influence of sink on extraction mechanical dis-
placement ventilation is apparent. When the extraction flow rate
increases, the sink effect radius, rex, and the sink velocity at the sink
effect radius, Vs(rex), increases. It causes the intensity difference be-
tween the sink outlet and the distance away from it at the same level
become sigificant. The intensity contour near the sink outlet has a
vertical distribution. As the distance away from the outlet increases,
the intensity at the same level decreases, i.e. the density increases.
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