Study on the Thermal Energy Storage Performance of PCM/SiC-based composite aggregates

Abstract

The construction buildings have attributed the global energy consumption. Especially, heating, ventilating and air conditioning (HVAC) are main factors on the energy consumption in buildings. Therefore, the environmental and sustainable technologies have applied to building as free cooling system to reduce the operation time and capacity of the conventional cooling system or heating system. Thermal energy storage systems with phase change materials (PCMs) could be beneficial way to enhance a building thermal energy storage performance. The researchers have studied the porous materials, such as adoptable and efficient, improving the energy efficiency in building. Light weight aggregate is significantly affordable materials that PCMs can be interfused to the porosity of light weight aggregate. In this study, Paraffin wax was used as the impregnating material due to stability and high phase change properties. However, Paraffin wax is composed of the oil content. Thus, silicon carbide (SiC) was used as the coating material on the surface of aggregate impregnated with paraffin wax to improve bonding strength between aggregate and cement paste. SiC is ideal inorganic fillers on the concrete system. Thus, PCM/SiC-based composite aggregates was manufactured with Air Cooled Blast Furnace Slag aggregate by various technologies, such as heat impregnating, fast cooling and mix coating method to apply to concrete. After PCM/SiC-based composite aggregates was manufactured, mechanical, chemical and thermal energy storage properties were conducted by various experiments and analysis. It verified that the mechanical properties of the concrete specimens with PCM/SiC-based composite aggregates were presented with satisfied results compared to Plain specimen. In addition, for evaluating thermal energy storage property, Mock-up structure was manufactured at square size (1.2x1.2m) and height of 1.2m with sensors, such as inserted, attached, placed. The thickness of wall is 20cm. After making Mock-up structures, every sensor was connected to Data logger, thereby data acquisition of temperature collected from every sensor for 33 days in summer season. As the results, thermal energy storage capacity of PCM/SiC-based composite aggregates was verified with decrease of temperature indoor room averagely 3℃. The phase change of PCM/SiC-based composite aggregates is started at 33 or 34℃ and it is changed to liquid state at 43 or 44℃. At this stage, temperature in concrete is not released to the outside. Thus, PCM/SiC-based composite aggregates can be stored a lot of thermal energy, thereby attributing the decrease of indoor room temperature.