Analysis of a Micro-Dispersed PCM Composite Behaviour in a Building's Wall for Different Climates

Abstract : The integration of phase change materials (PCMs) in buildings especially in the walls is the subject ofmore than a decade of growing interest due to their potentialities for energy saving and enhancementof thermal comfort. The present investigation concerns the applications related to thermal insula-tion. The composite wall studied here by numerical simulation is obtained by the incorporation ofshape-stabilized PCM particles in a polymer matrix. A novel model is developed to study the thermalbehaviour of this PCM-composite when used as a plane insulating material submitted to variable ther-mal modulations on one of its faces. The numerical model couples the heat transfer in the wall withthe heat transfer and the crystallization/melting process within PCM inclusions considered as spher-ical. Both processes are modelled by a finite volume approach combined with the enthalpy methodto account for the phase change. Simulation results are used to monitor the temperatures in the walland quantify the energy exchanges between its two sides. By varying the thickness of the wall as wellas the volume fraction of the incorporated PCM, the conditions for which the negative effect of thehigher PCM thermal conductivity outweighs the benefits related to energy characteristics of the phasechange of the PCM are evidenced. The analysis is extended to different external temperature modula-tions representing different typical seasons/climates. The results show the impact of the choice of thePCM phase change temperature on the wall thermal efficiency over the year. For the case investigated,it was shown that a good performing PCM during a summer day exhibits an unsatisfactory behaviourduring a winter day compared to a pure (without PCM) insulation material.