A novel building thermal energy storage PCM: lauric acid-palmitic acid- tetradecyl alcohol/vitrified beads

Abstract

In order to obtain a building thermal storage material with excellent thermal performance, sufficient strength and low leakage, the advantages of ternary PCMs (Lauric acid—Palmitic acid—Tetradecyl alcohol, LA-PA-TA) and vitrified beads (VB) as a adsorbent carrier were integrated to prepare a novel LA-PA-TA/VB composite PCM which exhibited favorable phase change temperature (i.e. 20.1–20.5°C) and low sub-cooling (0.4°C). Then, the novel LA-PA-TA/VB was, respectively, encapsulated with five different materials (a true stone paint emulsion, styrene-acrylic emulsion, EVA emulsion, epoxy resin and cement powder) to form a shape-stabilized LA-PA-TA/VB (SS-LA-PA-TA/VB) in order to reduce the leakage. The mass loss and mechanical properties experiments showed that SS-LA-PA-TA/VB encapsulated with the real stone paint emulsion-cement powder presented the optimal stability and reliability with low mass loss ratio of only 2.67% after 50 phase change cycles. The SS-LA-PA-TA/VB with the optimal package was further prepared into a thermal energy storage mortar (TESM) with different SS-LA-PA-TA/VB contents. The results show that the thermal properties of the TESM increased and the mechanical properties decreased with SS-LA-PA-TA/VB contents. However, even with the TESM with 30 wt% SS-LA-PA-TA/VB (30TESM), the compressive strength, flexural strength etc. still satisfy the requirement of the Chinese National Standard. The analysis shows that the hydrophobic functional groups are attached to the surface of the emulsion of the real stone paint, whereby a stable hydrophobic film was formed. In addition, the temperature regular ability and heat insulation performance of 30TESM and the referenced mortar were compared by temperature probe embedded inside the mortar blocks and installed in a small experimental room. The results indicated that the internal temperature of the mortar blocks, backside and central temperature in the small room was 5.4°C,5.6°C and 2.1°C lower than those of the referenced group, respectively. It is thus clear that the novel low cost TESM exhibits a good temperature damping effect and temperature control performance and may have a widespread application in the areas of building energy conservation.