| Summary: | 碩士 === 國立成功大學 === 建築(工程)學系 === 85 === This research is focusing on three-dimension dwelling space of
bedrooms in Taiwan residence, performing first through
technologies of concentration-decay method and importing the
concept of age of air, helping with the CFD for studying the
affects of two air exchange indices－local mean age of air and
the room mean age by varying the boundary conditions（ratio of
openings, locations of openings and directions of bed） under
the mode of natural ventilation. In this research, also creating
chambers of dwellin■ Objectives：1. According to current
existing domestic and foreign references concerning on indoor
air environment, through the application of CFD numerical
simulation, to study the distributions of CO2 concentration,
temperature and velocity of domestic dwelling-bedroom spaces.2.
To approach the influences of ventilation and air exchange in
bedrooms by the ratio, locations of openings and directions of
bed for looking forward to establishing relative basic data as
the reference of bedroom*s designing.3. Through the
concentration-decay experiments of bedroom*s experimental field,
looking forward to establishing the initial index of bedroom*s
age of air and ensuring the usage of concentration-decay
experiments applied to bedroom space.4. To ensure the usage and
correction of CFD numerical simulation applied to the simulation
of natural ventilation of bedroom*s spaces.■ Methodology：1.
Referring to previous researches, by comparative analysis of
behavior models, space range and mold distance scale, a bedroom
with space range of 3 meter length, 2.4 meter width and 3 meter
height as a preliminary research object.2. On the basis of the
space range of the chosen bedroom, build up the bedroom*s
experimental laboratory of simulating natural ventilation for
performing the 32-case concentration-decay experiments under
different conditions of the ratio of openings, width of openings
and directions of bed.3. According to the built CFD bedroom*s
chamber, using different ratio of openings, width of openings
（10, 20cm） and directions of bed as variables, to simulate the
distribution of the field of velocity, temperature and CO2
concentration by applying the software PHOENICS of fluid
mechanics and searching for the best direction of bed through
studying the section velocity field of human body and
openings.4. To prove the reliability of the CFD simulation
applied to the natural ventilation by analyzing the results of
CFD numerical simulation and concentration decay.■ Results：1.
Applying the tracer gas（SF6）concentration decay method to
measures of age of air in the dwelling bedroom is reliable and
useful. In the quantitative indices of age of air, the local
mean age of air under one hour of contaminant particles at any
point in bedroom is better below 2230 seconds and the room mean
age of air is better below 1414 seconds.2. By the experimental
results, we can find the growing return-flow phenomenon of
contaminants when the increasing of opening width, especially at
the boundary of openings having the most variable age of air.3.
The most marked location to lower local and room mean age of air
is the one nearest the side of openings；the location opposite
the openings for lowering the local mean age of air is most
marked；the most marked location of openings to lower the local
and room mean age of air is the one nearest the occupant*s head.
In conclusions described above, to air exchange efficiency the
best location and direction of bed is the one nearest the
openings and occupant*s head when opening is 20cm width, we can
get th4. The interior average temperature can be lowered about
0.2℃, the expansion of CO2 concentration can be increased to
150~180ppm when the width of openings is increased from 10 to
20cm.The two sides of the thermal plume produced by head in
bedroom will appear two symmetric cycle-flows and a axis in the
middle, the varieties of this axis location can determine the
distribution of interior air environment. Especially when the
head is nearest the side of openings, it can lower the
temperature and CO2 concent5. Under the influences of buoyancy,
the interior average temperature can increase 2℃, the CO2
concentration will block together under the ceiling to 880ppm
and the CO2 concentration at the opening boundary will produce
the phenomenon of return-flow in the dwelling bedrooms. From
above, we can prove the interior buoyancy and strength of
outdoor flow can determine the in-out behavior of the
contaminants at the opening boundary.
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