The impact of wall emissivity on the thermal and dynamic behavior of an air channel integrated into the roof

Abstract

Because roofs provide a large area to collect solar energy, they can be exploited to arrive at an architectural element
that can act as a solar collector and participate in the improvement of thermal comfort. in this axis and in order to
show the importance of radiative exchanges in thermosyphon systems and the choice of roofing construction
materials; a 3D numerical study is carried out on the natural convection coupled with radiative exchanges in an
inclined air channel (using the commercial computational fluid dynamics software FLUENT). Emissivity values
tested correspond to those of some building materials. From our results we affirm that the emissivity of the external
roofing affects the dynamic and thermal behavior of the channels integrated under the roof. So a good choice of
material roofing is recommended in order to getting a maximum air heating by solar radiation.