Experimental and unified mathematical frameworks of water-ice phase change for cold thermal energy storage

Cold thermal energy storage (CTES) is a process that supplies cold thermal energy to a medium for stor-age and extracts it whenever is needed. The storage medium is phase change material (PCM), which makes great use of the large quantity of latent heat released during solidification or melting. However, some key fundamental and applied issues have not yet been resolved: how do we overcome the ther-mal interference in PCMs from unstable microscopic crystallization and external mechanical forces? Are there any unified and robust models to predict the whole time evolution of phase change accurately and rapidly? To fulfill these research gaps, we firstly establish a novel, well-controlled experimental system for PCMs that mitigates the thermal disturbance over a medium to large volume during solidification, capable of measuring transient temperature data and characterizing freezing stages at both macro-and micro-scale. We also develop in detail a unified semi-analytical mathematical framework to model the solidification of PCMs, consisting of five subsequent stages: liquid supercooling, nucleation, recalescence, equilibrium freezing, and solid subcooling. The modeling results yield a good agreement with our exper-imental data in several scenarios, particularly the nucleation temperature and time as well as the total freezing time are accurately predicted. Lastly, we extend our study to investigate the thermal effects of various radial positions, geometries, initial temperatures, heat transfer fluid temperature, and heat trans-fer coefficients in the context of CTES system. (c) 2022 Elsevier Ltd. All rights reserved.

Automated summary

In this study, we address the thermal interference and time evolution prediction of phase change materials (PCM) in the field of cold thermal energy storage (CTES). By establishing an experimental system and developing a mathematical model, we obtain accurate experimental and simulation results.