Comparative analysis of form-stable phase change material integrated concrete panels for building envelopes

Abstract

Phase change materials (PCM) can reduce energy consumption and improve thermal comfort in buildings. However, they have some limitations in integrating into construction materials. The significant difficulty is the selection of suitable porous materials, which should be compatible with construction materials with high PCM absorption capacity and strength and no seepage, leakage, or acidification. Therefore, this study aimed to select suitable porous material for developing Form Stable PCM (FSPCM) cement composite that can be integrated into concrete panels for building envelopes. It considered five different porous materials based on their porosity, geometry, and surface morphology to encapsulate the capric acid (CA). The synthesized FSPCM composite was tested for seepage, leakage, and chemical stability before its integration into a cementitious composite to develop concrete panels. Thermophysical properties and thermal performance of those FSPCM and concrete panels were measured following ASTM standards and compared using six indicators: absorption, thermal conductivity, strength, thermal inertia, latent heat storage and thermal storage. The comparative analysis revealed that silica aerogel granules (SAG) have stably encapsulated CA up to 80 wt% due to its high porosity, whilst recycled expanded glass (REG) absorbed only 25 wt%. The Capric acid-Silica Aerogel Granule (CASAG) integrated concrete panel had the least compressive strength (3.66 MPa), but it had the lowest thermal conductivity (0.39 W/m-K), higher storage (690 kJ/m3) and higher thermal inertia (1.32 °C). In contrast, the Capric Acid/Recycled Expanded Glass (CAREG) panel had the highest compressive strength (13 MPa), but its thermal conductivity was also very high (1.0 W/m-K), and had lower storage (542 kJ/m3) and thermal inertia (0.62 °C). However, the Capric Acid/Hydrophobic expanded Perlite (CAHEP) panel had moderate compressive strength and thermal conductivity, and its thermal inertia and heat storage were comparable to CASAG-integrated concrete. Overall, the CAHEP showed the best performance in terms of the six indicators and therefore was recommended to be the best porous material to absorb polar PCM like CA to develop FSPCM integrated concrete panels for building envelope applications.