HEAT TRANSFER ENHANCEMENT OF PHASE CHANGE MATERIALS FOR THERMAL ENERGY STORAGE SYSTEMS

摘要

Solar water heaters (SWHs) are a well-established renewable energy technology that have been widely adopted around the world. The downfall of this technology is rooted in the inconsistency of solar intensity from day to night. In the recent studies, the application of energy storage materials such as phase change materials (PCMs) has attracted many attentions; however, PCM by itself may not be effective due to the poor heat transfer rate, low thermal dijfusivity and thermal conductivity. This paper aims to explore the thermal performance of energy storage-transfer materials to be applied in conjunction with PCMs. The selected types of PCMs are paraffin waxes with melting point temperatures of 28-72 C. In the first analysis, silicone oil is selected as the heat transfer medium with high thermal stability. The melting point and specific heat capacity were measured by a modulated differential scanning calorimeter (MDSC). The obtained results show that silicone oil will lead to melting point depression of maximum 3°C in the PCMs. In the second analysis, the heat transfer enhancement by addition of nanoparticles has been investigated. The selected nanoparticles for this analysis are Aluminum Oxide (Al_2O_3) and Cupric Oxide (CuO). The obtained results from this study show thermal performance improvement of the PCMs which can be applied to different thermal energy storage systems, such as in the case of solar thermal collectors for the application in SWH technology.