| Summary: | 碩士 === 國立臺灣科技大學 === 機械工程系 === 106 === The purpose of this research is to study the mechanical extraction
ventilation in two connected rooms. In two connected rooms,
there is a heat source (buoyancy source) in one of two rooms, which
is denoted as the forced room, and there is an extraction device in
the other room, which is denoted as the extraction room. The seriesconnected
and parallel-connected models are investigated. The seriesconnected
model has an opening between the ambient and the forced
room. The parallel-connected model has one additional opening between
the ambient and the extraction room, and two rooms have
their individual connecting openings to the ambient. In the theoretical
analysis part, the solutions of physical parameters are obtained
by using the pressure differences at the connecting openings, the
plume model and the conservation equations of mass and buoyancy.
A two-room reduced-scale acrylic model is used to conduct the laboratory
experiments by using the salt-bath technique. According
to the ventilation type and the connection type of the model, experimental
cases are categorized into three sets, Set 1, the seriesconnected
model of natural ventilation; Set 2, the series-connected
model of mechanical ventilation; Set 3, the parallel-connected model
of mechanical ventilation. Set 1, natural ventilation, repeats the previous
research work by changing the exit opening location. Either
of Set 2 and Set 3 includes three experiments with different extraction
flow rates, Qex = 9, 18 and 27 cm3/s. Experimental results
of natural ventilation in the series-connected model show when the
vertical distance between the buoyancy source and the exit opening
increases, the volume flow rate of the space also increases, and it
achieves the same effect as that of increasing the extraction volume
flow rate in mechanical ventilation in the series-connected model.
In the parallel-connected model of mechanical ventilation, there is
no flow between the ambient and the extraction room when the internal
connecting opening is covered by the dense salt water layer
of the extraction room. The volume flow rate of the forced room
is always the same as the mechanical extraction volume flow rate
in the series-connected model, but has a limit value in the parallelconnected
model when the mechanical extraction flow rate is large
enough. This research also finds that the momentum flux from the
internal connecting opening causes the different flow stratification
in the extraction room in the series-connected model of mechanical
ventilation when the flow rate is large enough. Therefore in the
series-connected model of mechanical ventilation, the internal connecting
opening and the extraction sink location both influence the
flow stratification in the extraction room for the large extraction flow
rate case.
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