Anon Anan-archa. A new type of skylight solar chimney for tropical climate. Doctoral Degree(Energy Engineering Technology). King Mongkut's University of Technology North Bangkok. Central Library. : King Mongkut's University of Technology North Bangkok, 2023.
A new type of skylight solar chimney for tropical climate
Abstract:
This dissertation is aimed to design and investigate the thermal performance of
a new modular configuration of roof integrating skylight and solar chimney intended
to reduce heat gain admission, induce ventilation and ensure sufficient indoor
illuminance. This integrated Skylight Solar Chimney (SSC) configuration is
composed of three layers: a 1 mm. thick clear acrylic layer on the outside, a set of
1 mm. thick aluminum slats distanced each other at the middle and a layer with a
combination of clear acrylic and aluminum slats at the inner side. The dimensions of
the SSC are 0.50 m x 1.50 m x 0.15 m (W x L x H). A 0.025 m2 outlet opening was
located at the top lateral side whereas two inlet openings of similar surface area were
installed on the bottom lower layer (one inside the room and another outside). To
assess SSC performance, two small rooms of 2.52 m3 volumes were built using
concrete blocks for walls and corrugated cement panels for the south facing roof
slopped at 30 degrees.
In the first part of experiments, the roof of the first house, which served as a
reference, integrated a transparent corrugated panel whereas the other house
integrated the SSC. Three scenarios of SSC inlets were considered. Field test results
showed that in all scenarios the indoor temperature of room with SSC was 1 to 4 degrees Celsius
lower that of the reference room and varied following ambient conditions. When both
inside and outside inlet openings were used, the highest temperature difference was
observed. The measured heat flux through the roof of reference house was much more
important than all SSC scenarios, a 50% difference was observed when both SSC
inlets were open. This clearly demonstrated SSC efficiency to reduce heat gain. The
air change (ACH) induced varied between 2 to 29. SCC indoor illuminance was about
50% lower than that of the reference house.
The second part of the experiment was aimed to determine the optimum
position of the intermediate layer composed of distanced aluminum slats. The first
room included SSC with intermediate layer located at the middle between the top and
lower layers whereas in the second room, the position of intermediate was varied to
be near the top layer (second configuration) and near the lower layer (third
configuration). Field tests showed that the position of intermediate layer did not affect
indoor temperature significantly as temperatures were relatively close. However, the
lowest heat flux transmitted through SSC and lower illuminance are observed when
located near the lower layer. The induced air change was more or less similar for the
three positions considered.
The thermal performances of SSC were simulated using Solidworks flow
simulation software package. Simulation results agreed well with experimental
results: installing the intermediate layer near the top leads to lowest temperatures
compared to the other configurations. The highest air temperatures were observed
when the intermediate layer was located near the bottom layer.
Therefore, it is recommended that for practical application, the appropriate
position for SSC intermediate layer should be located between the middle and lower
layer as it will lead to good ventilation rate, lower indoor temperature and less heat
gain transmission without glare. Adjustment of the position can be depending on
architectural requirement and daylight control.