Carbonate salt based composite phase change materials for medium and high temperature thermal energy storage: From component to device level performance through modelling

Abstract

This paper concerns the thermal performance of composite phase change materials (CPCMs) based thermal energy storage (TES) from component to device levels. The CPCMs consist of a eutectic salt of NaLiCO3 as the phase change material (PCM), an MgO as the ceramic skeleton material (CSM) and graphite flakes as the thermal conductivity enhancement material (TCEM). A computational model describing the transient heat transfer within the CPCMs module and component is developed and validated by experiment. Extensive modelling is then performed to investigate the performance of TES from component to device levels. Firstly, the influences of CPCMs properties, module size and surface roughness on component performance are evaluated. The results show that a higher mass loading of TCEM gives a higher thermal conductivity at CPCMs module level and hence a shorter charging/discharging process at component level. A larger CPCMs module and a higher heat transfer fluid inlet velocity achieve a remarkable improvement on component performance. The CPCMs based device is then investigated with a focus on the effect of the component arrangements. The results indicate that the trapezoidal configuration offers the best performance with the total charging process being shortened by 55.6% and 34.8% in comparison with the parallel and interlaced configurations.