Analysis of micro-dispersed PCM-composite boards behavior in a buiding's wall for different seasons
Abstract
The integration of phase change materials (PCMs) in buildings especially in their walls is the subject of
more than a decade of growing interest due to their potentialities for energy saving and enhancement of
thermal comfort. The present investigation concerns the applications related to thermal insulation. The
idealized composite wall considered here numerically can be thought of as resulting from the in-
corporation of shape-stabilized PCM particles in a polymer matrix. A novel model is developed to study
the thermal behavior of this PCM-composite when used as a planar insulating material submitted to
variable thermal modulations on one of its faces. The numerical model couples the heat transfer in the
wall with the heat transfer and the crystallization/melting process within PCM inclusions considered as
spherical. Both processes are modeled by a finite volume approach combined with the enthalpy method
to account for the phase change. Simulation results are used to monitor the temperatures in the wall and
quantify the energy exchanges between its two sides. The thickness of the wall and the volume fraction
of the incorporated PCM were varied in this study. This analysis permits to point out the configurations
for which the negative effect of the higher thermal conductivity of the PCM outweighs the benefits
related to its latent heat. The analysis is extended to different external temperature modulations re-
presenting different typical seasons/climates. The results show the impact of the choice of the PCM phase
change temperature on the wall thermal efficiency over the year. For the case investigated, it was shown
that a PCM composite board with increased performances during a summer day exhibits a degraded
behavior during a winter day when compared to a pure (without PCM) insulation material.