Bench-scale long-term phase change material analysis for thermal energy storage design

Thermal energy storage is indispensable to realize carbon neutral energy systems, enabling flexible coupling of thermal and power sectors with e.g. heat pumps. Phase change materials (PCMs) are an attractive compact thermal energy storage (TES) counterpart, to move beyond the state-of-the-art in sensible TES. Although many PCM intrinsic property data exist, their thermal cycling data at application-representative volumes are scarce. To address this gap, here, two bio-based PCMs: RT57HC and RT60HC were analysed in a bench-scale (~44 l) shell-and-tube PCM-TES system respectively for 27 and 53 complete cycles, between 35-80 °C. The results show quite consistent TES capacity. Where, the maximum difference between the average storage capacity and each cycle for heating and cooling was only 0.5% and 0.5% for RT57HC and 0.8% and 0.3% for RT60HC. Both PCMs show no supercooling, and only 6-8 °C maximum hysteresis, making them ideal candidates for the considered PCM-TES applications.