Experimental investigation of the impact of design and control parameters of water-based active phase change materials system on thermal energy storage

Abstract

Phase Change Materials (PCM) has the potential to reduce building energy consumption and emissions, which is essential to combat the climate change threat. Theoretically, PCMs are reported to achieve massive energy savings in buildings. However, in real-life scenarios, the results vary vastly from the theoretical or experimental results due to many factors and parameters that need to be taken into consideration. This study is an extension of a previous study of the present authors where an active PCM system installed in a multi-storey building was reported to be inefficient and not achieving the desired savings. To understand the reasons, this study experimentally investigated the influence of inlet water temperatures and flowrates on the melting, solidification and energy storage of active PCM system using a small-scale model of the real system. The results showed that the PCM solidification rate strongly depends on the inlet water temperature and is less sensitive to the inlet water flow rates. The lower the inlet water temperature, the shorter the time required to solidify the PCM. However, at higher flow rates, PCM melts and solidifies more uniformly compared to lower flow rates. The optimum inlet water temperature to solidify all panels inside the PCM tank also depends on the length of the PCM tank. The longer the PCM tank, the lower should be the inlet water temperature to ensure complete solidification of PCM panels towards the end. For the studied system, 8 °C inlet water temperature was recommended to ensure complete solidification of PCM panels inside the tank. Moreover, the PCM was never 100% solidified or melted, which means a loss factor should be considered when a PCM tank is designed. The findings of this study will assist the designers/engineers in designing an active PCM system that can achieve the desired savings in real life and minimize the energy performance gap.